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1
Bordeian, Georgeta Simona. "Characterisation and properties of alkali activated pozzolanic materials." Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/19371/.
Full textAbstract:
Many of the waste materials produced from modem heavy industries are pozzalans, which develop cementitious properties when finely divided in the presence of free lime. This property allows a potential industrial use for this waste as a cement replacement material in concrete. An example of such a waste material is blast furnace slag from the smelting of iron and steel. The US produces 26 million tons of blast furnace slag annually. Most of the slag is slowly cooled in air and it makes a poor pozzolan. Only 1.6 million tons of the slag is available in the granulated form, which is suitable as a cementitious and pozzolanic admixture. Most European countries are well endowed with coal-fired power stations and this produces fly and bottom ash, flue gas desulphurisation (FGD) gypsum. However, less than 25% of the total ash from power stations has found an industrial use mainly in cement and concrete industry. This creates a massive waste-disposal problem. Disposal of unused fly ash in open tips and ponds, for example, creates pollution problems since the drainage of effluents from the ash in the deposit ponds threaten water supplies by polluting the ground water with traces of toxic chemicals. Recent research has concentrated on the alkali activation of waste pozzolanic materials, especially ground blast furnace slag. This thesis has investigated the alkali activation of low calcium fly ashes. These form very poor pozzolans and the alkali activation of the fly ash offers the opportunity for the large scale use of fly ash. Water glass was selected as a suitable activator for the fly ash. A comprehensive series of tests have been carried out to gain information on the effect of different parameters, such as proportion and composition of the constituent materials, curing conditions and casting methods, in developing high performance construction materials. Laboratory investigations were carried out to determine the following characteristics of alkali activated materials: density, water absorption, apparent porosity and coefficient of saturation, drying shrinkage, compressive creep, compressive, flexural and tensile splitting strength, dynamic modulus of elasticity, accelerated weathering (freeze-thaw cycle) resistance, fire resistance (temperatures up to 600°C), microstructure, macrostructure and investigation of hydration phases by SEM, ED AX, Digital-mapping and X-ray diffraction. The influence of key parameters e.g. slag content, curing method, water/binder ratio and water glass hardener content on the mechanical properties were determined. Optimisation of the alkali-activation of fly ash materials was achieved by blending this with other pozzolans such as silica fume and slags. Mechanical properties were further improved by using moulding pressures and by thermal treatment. The use of short fibre reinforcements was investigated to overcome microcracking, volumetric deformation and creep in the materials. The free shrinkage and creep of the materials agree with the model developed by Mangat and Azari for fibre reinforced Portland cement composites. Other additives were also investigated to improve workability, frost and water resistance and physical properties of the alkali activated materials. The fundamental relationships between chemical composition, hydration phases,microstructure and engineering properties (strength, durability and stability) of alkali activated materials were investigated. It is clear that strength development is a function of the hydration products developed and these are affected by the mix composition and the curing temperature. The current work found parameters such as the Si/Al ratio, the Ca/Si ratio and the Na20 content to be important. These chemical parameters decide the principal phases in the hydration products formed in alkali activated materials, between calcium silicate hydrate (C-S-H) and zeolite of the form (R[2]0 n Al[2]O[3] x SiO[2] r H[2]O).Overall the thesis shows the great potential of alkali activated materials to produce high strength construction materials. Limitation in the shrinkage of the materials can be overcome by the use of fibre reinforcement. At the end of the thesis limitations and suggestions for further work are made.
2
Chapagain, Indra Prasad. "Mechanical properties of self-consolidating concrete with pozzolanic materials." FIU Digital Commons, 2008. http://digitalcommons.fiu.edu/etd/2111.
Full textAbstract:
Self-consolidating concrete has been described as the most revolutionary development in concrete technology in several decades with the ability to flow freely through closely spaced reinforcements, expel entrapped air and self compact without vibration. Since it was first developed in Japan in the early 1980's, major development in the chemical admixture technology has made SCC more viable.
An experimental study was conducted to identify the mechanical properties of SCC by optimizing the use of pozzolanic materials and local aggregates with some proposed statistical models. The research was focused to investigate compressive strength, splitting tensile strength, modulus of elasticity and drying shrinkage behavior of concrete. The results were established experimentally and compared with the available SCC research data based on extensive literature study.
Besides the improved mechanical performance, results indicate that the use of pozzolanic materials and local aggregate in SCC is recommended in terms of its cost benefit value.
3
Meral, Cagla. "Using Perlite As A Pozzolanic Addition In Blended Cement Production." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605259/index.pdf.
Full textAbstract:
Perlite is a volcanic glass which has high amount of silica and alumina. Those properties make it a candidate, if finely ground, for being used as a pozzolan. The studies on the pozzolanic properties of perlite are very limited, and none of them has dealt with the use of perlite in the blended cement production.
The aim of this study is to investigate the pozzolanic properties of perlite, and if appropriate to investigate perlite&rsquos usability in blended cement production. For this purpose, perlites from two different sources &ndash
Izmir and Erzincan - are used as replacement of portland cement clinker with two different percentages: 20% and 30% by weight of total cement. Then for each different composition, materials are ground with some gypsum in order obtain grinding curves for the resultant cements. After obtaining the grinding curves, a total of 22 cements with two different finenesses are produced by intergrinding and separately grinding the materials for each composition. The obtained cements are used in paste and mortar production so that normal consistencies, setting times, autoclave expansions, and compressive strengths are determined.
4
Kalakada, Zameer. "Experimental Investigation on Recycled Glass Powder as a Pozzolanic Cement." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/393612.
Full textAbstract:
Cement is the main ingredient in concrete, and the production of cement is a costly and energy absorbing process. In addition, production of cement ominously contributes to environmental pollution, as 1 ton of cement releases about 0.9 ton of CO2 in the atmosphere. Since cement is the material which is primarily responsible for the cost and the pollution, there is a critical need to develop materials which exhibit cementitious property and could be used as a substitute of cement. Supplementary Cementitious Materials (SCM), are substances which possess cementitious properties, hence they can be used as a partial/total replacement of cement.
Recently, use of recycled material, such as waste glass powder (WGP), has received augmented attention in the concrete industry. At first, waste glass was used as an aggregate replacement in concrete and it was observed that the mechanical and durability properties of the modified concrete were degraded due to the increased potential of Alkali-Silica Reaction (ASR). Later, literature studies have shown that ASR occurrence in concrete is dependent on the particle size distribution of the glass used. As the particle size decreases the ASR probability reduces. These results motivated the use of recycled glass powder (RGP) with microscopic particle size distribution as cement replacement. There are multiple benefits of using RGP as cement replacement: firstly, using a waste material would reduce the load on the landfills, secondly, the total cost would be less as recycled WGP is replacing the costly cement; and finally, the use of RGP would lead to sustainable construction as a consequence of a decrease in cement manufacturing.
The present study deals with the experimental investigation on RGP as a pozzolanic cement. The Glass Powder (GP) used in this experiment was provided by the Australian company, Enviro Sand who supplied samples with two particle sizes of 75 μm and 150 μm for the purpose of this research. The main aim of this research project is to study the pozzolanic performance of GP having a particle size smaller than 150 μm. The current study involves an extensive experimental program which includes: density, compressive strength, tensile strength, pozzolanic activity, water absorption, chloride resistance, heat of hydration and drying shrinkage. Extensive concrete specimens of standard cube, cylinder and rectangular prism of standard dimensions are prepared to investigate the various material, strength and durability properties by varying the GP content. In addition, present experimental work consists of enhancing the pozzolanic performance of the GP by varying the curing conditions and modifying the mix design. In total, about 700 specimens were tested in three stages in this experimental research work
The optimisations resulted in Strength Activity Index (SAI) of coarse GP which was comparable to the SAI values of much fine GP reported by the earlier published research works. Since a considerable amount of energy would be consumed in grinding the glass from coarse to fine, the grinding energy would in turn lead to increment in the cost and rise in harmful carbon di oxide emissions. The current research is significant owing to the multiple benefits mentioned in the previous paragraph, furthermore, locally, according to a recent report from Australian National Waste, Australia generates around 1.1 million tonnes of glass waste which is equivalent to about 45 kg glass per capita and approximately 44% of it is landfilled. This practice of dumping the glass waste in landfills is environmentally unsustainable, since glass is non bio-degradable in nature. The last stage mix design alteration resulted in a maximum SAI of 117%. In addition, it resulted in higher resistance to chloride ion penetration of 17% and about 23% lower heat of hydration than the control mix at 30% replacement of the coarse GP.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
Full Text
5
Ahmed, Mohammad Sharfuddin Aerospace Civil & Mechanical Engineering Australian Defence Force Academy UNSW. "Effects of systematic increase in pozzolanic materials on the mechanical, durability, and microstructural characteristics of concrete." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace, Civil and Mechanical Engineering, 2007. http://handle.unsw.edu.au/1959.4/38645.
Full textAbstract:
The use of high performance concrete in construction has been enhanced by the use of pozzolanic materials. However, the use of these materials has not been optimized. Such optimization may be achieved by a systematic increase in the amount and combination of pozzolanic material additions, with accompanying studies of their effects on the mechanical, durability and microstructural characteristics of blended concrete. This work evaluated various concrete durability issues by studying systematic increases of pozzolanic materials such as fly ash and blast furnace slag (BFS) in the range of 25, 50 and 70%, and silica fume at 10% of total cementitious materials, forming various binary and ternary concrete blends. The concrete specimens were cured for a period of seven days after demoulding in line with widely practiced commercial curing procedures. The research explored the role and effectiveness of various binary and ternary blends of pozzolanic materials on the mechanical, durability and microstructural characteristics of concrete. Durability was evaluated by two independent rapid chloride permeability tests measured as charge passed and chloride conductivity from the RCPT and UCT tests respectively. These two rapid tests were coupled with long-term ponding tests to evaluate chloride ingress and the extent of corrosion for a period of two years. Further durability tests such as carbonation, drying shrinkage and porosity of these blends were also undertaken. This study also utilized micro-analytical techniques such as X-ray diffraction and Scanning Electron Microscopy to follow the hydration mechanism in various binary and ternary blends. Statistical significance testing was used to analyse and confirm all experimental results and conclusions. It is well known that a level of caution is exercised in the construction industry in the use of ternary blends. This study aims to evaluate the durability aspects of ternary concrete blends, in addition to binary blends, for resistance to chloride, corrosion, carbonation attacks and provide recommendations relating to the limits of blending level, as well as exposure conditions for blended concretes, based on the results of this study. It is expected that this will fill a major knowledge gap observed in the concrete industry. A comparison of two rapid chloride permeability tests such as UCT and RCPT indicates that the UCT test is easy and practicable, and does not contradict results obtained in the standard RCPT. However, the statistical significance of results obtained for some blends was only able to be established by using the RCPT. This effect can be attributed to the larger size specimens compared to UCT. The recommended blend to acquire both early-age and long-term strength development in fly ash is the ternary blends comprising 10% silica fume and 25% fly ash cast using lower w/b ratio. In addition, the same blend exhibited lower carbonation depth, lower charge passed from RCPT, lower chloride ingress and higher corrosion resistance characteristics from long-term ponding test compared to other blends of fly ash. In BFS blends, an increase in compressive strength was observed only in the specimens of 25% BFS compared to other higher percentage blends, while the higher addition of 50 and 70% replacement showed no significant difference in compressive strength between them and their corresponding ternary blends with addition of silica fume. The results of this study indicate that control (OPC) specimens cast with increased w/b ratio of 0.48 showed higher chloride ingress compared to both binary blends of 70% fly ash and 70% BFS specimens. This indicates that (OPC) cast using higher w/b ratio is to be avoided in chloride environments. On the other hand, though, the ternary blends of 10% silica fume and up to 50% fly ash exhibited lower chloride ingress compared to their respective binary blends of fly ash. However, these ternary blends exhibited lower compressive strength, more negative corrosion potential and higher corrosion rate, compared to the respective binary blends of 25% fly ash and its ternary blends. Therefore, the recommended blend observed in the long-term ponding test is the ternary blend of 25% fly ash and 10% silica fume. The recommended level of corrosion resistance in slag specimens is achieved by the use of ternary blends comprising silica fume at 10% added to the blend that contains up to 70% slag. However, the recommended level of slag for a lower carbonation effect is the use of a ternary blend comprising 50% slag and 10% silica fume (3B5S1) which showed a carbonation depth of 10.8 mm and a compressive strength of 53.2 MPa after 365 days of exposure. The drying shrinkage of concrete increased with the increase in fly ash and the same trend was observed in BFS specimens. However, the results were not significantly different between their respective blends. The extent of carbonation in fly ash specimens was higher compared to BFS blends specimens. This can be attributed to the formation of dusty and weak surfaces on the outer surface in addition to the excessive leaching of sodium chloride solution from the long-term ponding test in the former specimens compared to later. The high volume pozzolanic materials, irrespective of fly ash or BFS and addition of silica fume (70% fly ash and 10% silica fume, and 70% BFS and 10% silica fume), showed higher cumulative pore volume indicating that these blends with seven days of curing were not beneficial. These high volume ternary blends required prolonged curing to release portlandite from the hydration of cement to continue the pozzolanic reaction. This study has shown that 7-days curing of the pozzolanic concrete is inadequate if pozzolanic activity is to be invoked. This is particularly the case when it is expected that the concrete is likely to be subjected to a harsher than usual environment characterised by a dry atmosphere.
6
Erdem, Tahir Kemal. "Investigation On The Pozzolanic Property Of Perlite For Use In Producing Blended Cements." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12605964/index.pdf.
Full textAbstract:
Perlite is a glassy volcanic rock that contains approximately 70-75% silica and 12-18% alumina.
There are very large perlite reserves in the world (~6700 million tons) and approximately two thirds of these is in Turkey.
Due to its high amounts of silica and alumina, at the beginning of such a study, it seemed that it would be worth first to find out whether perlite possesses sufficient pozzolanic property when it is a finely divided form and then to investigate whether it could be used as a pozzolanic addition in producing blended cements.
In this study, perlites from two different regions (izmir and Erzincan) were tested for their pozzolanic properties. After obtaining satisfactory results, grindability properties of the clinker, perlites and their different combinations were investigated. Several blended cements with different fineness values and different perlite amounts were produced by either intergrinding or separate grinding methods. The tests performed on the cement pastes and mortars containing the blended cements produced were as follows: Water requirement, normal consistency, setting time, soundness, compressive strength, rapid chloride permeability, resistance to sulfate attack and resistance to alkali-silica reactions.
The results showed that Turkish perlites possess sufficient pozzolanic characteristics to be used in cement and concrete industry. Moreover, the properties tested in this study satisfied the requirements stated in the standards for blended cements. The durability of the mortars was found to be improved by 20% or more perlite incorporation.
7
Uzal, Burak. "Properties And Hydration Of Cementitious Systems Containing Low, Moderate And High Amounts Of Natural Zeolites." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608974/index.pdf.
Full textAbstract:
The extent of the benefits provided by use of SCMs in cementitious systems increases as their percentage amounts in total binder increases. However, the proportion of SCMs in cementitious systems is limited, especially for natural pozzolans, by some factors such as increase in water requirement and decrease in rate of strength development. Therefore investigations are needed to increase the amount of natural pozzolans in blended cements or in concrete as much as possible without decreasing their performance. This aim requires studies on cementitious systems with more reactive natural pozzolans than widely-used ones.
The objective of the study was to investigate the pozzolanic activity of natural zeolites (clinoptilolite) from two localities in Turkey, and properties of cementitious systems containing low (15%), moderate (35%) and high (55%) amount of them. The study covers characterization of the natural zeolites used, evaluation of their pozzolanic activity in comparison with some popular mineral admixtures, and properties of pastes, mortars, and concrete mixtures containing low, moderate, and high amounts of natural zeolites.
Reactivity of the natural zeolites with Ca(OH)2 was found to be higher than those of the fly ash and the non-zeolitic pozzolan, but lower than that of the silica fume.
Natural zeolite blended cements were characterized with the following highlighted propertiesfaster setting than portland cement, low amounts of Ca(OH)2 and capillary pores larger than 50 nm in hardened pastes, relatively dense microstructure of hardened paste than portland cement, more compatibility with melamine-based superplasticizer than being with naphthalene-based one, and excellent compressive strength performance. Concrete mixtures containing natural zeolites as partial replacement for portland cement were characterized with the following properties
7-day compressive strength of ~25 MPa and 28-day strength of 45-50 MPa with only 180 kg/m3 portland cement and 220 kg/m3 zeolite dosages (55% replacement), comparable modulus of elasticity with plain portland cement concrete, &ldquo
low&rdquo
and &ldquo
very low&rdquo
chloride-ion penetrability for low and large levels of replacement, respectively.
8
Morel, Bayram Murat. "Investigation Of The Effects Of Temperature On Physical And Mechanical Properties Of Monolithic Refractory Made With Pozzolanic Materials." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606700/index.pdf.
Full textAbstract:
In recent years, scientific studies are carried out to find new refractory
material. Having good mechanical properties under very high temperatures,
refractories are widely used in industries like iron, steel, glass, cement and pottery.
Researches are focused on monolithic refractory making because of their superior
properties comparing to conventional firebrick refractories. Providing a mono-block
body, having no joints makes the monolithic refractories more durable at elevated
temperatures. Easier production and installation are two main points that people are
choosing monolithic refractories, thus an economy is made.
In this study, for monolithic refractory production, high alumina cement was
used as binding material. It is known that the increase in alumina (Al2O3) content
increases the high temperature resistance, so that crushed firebrick, having 85%
Al2O3 was used as aggregate. Pozzolanic materials, which are silica fume, fly ash,
ground granulated firebrick and ground granulated blast furnace slag, were added to
improve physical and mechanical properties of mortar. With the addition of steel
fibres, change in compressive strength and flexural strength was observed.Superplasticizer was used to understand its behaviour under high temperatures.
Portland cement containing mortars were also prepared to make comparison with
high alumina cement containing specimens.
Specimens were prepared in 5x5x5 cm and 4x4x16 cm prisms. They were
cured for one day at curing room, then heated to 105°C and then heated to 1100°
C. Weight, size and ultrasound velocity change, compressive strength and flexural strength tests were done to determine physical and mechanical properties of the monolithic refractories, before and after heating. Heated and non-heated specimens were pulverized for microstructural investigation with X-Ray diffraction (XRD) method. Using high alumina cement with 50 &ndash
60 % granulated blast furnace slag or granulated firebrick, by the weight of cement, and crushed firebrick as aggregate, a satisfactory monolithic refractory material was made. It was observed that, mechanical properties were decreased at the Portland cement used mortars after several times of heating and cooling cycles. Also, it was determined that the microstructure of the high alumina cement containing mortars did not deteriorate much at 1100°
C, as long as there was no change observed from the results.
9
Fagundes, Luiza Perroni. "Utilização de resíduo de cerâmica proveniente de olarias para estabilização de solo laterítico /." Ilha Solteira, 2019. http://hdl.handle.net/11449/181162.
Full textAbstract:
Orientador: Mauro Mitsuuchi TashimaResumo: O modo como são dispostos os resíduos gerados pela indústria, pela agropecuária e pela sociedade gera uma preocupação crescente. Muitas pesquisas têm sido desenvolvidas com a finalidade de diminuir o impacto que estes causam a sociedade e ao meio ambiente. Diversos resíduos têm sido estudados como materiais cimentícios suplementares para substituição de parte da quantidade de cimento, contribuindo para a redução de áreas de aterro e também na diminuição da emissão de CO2 associada à produção de cimento Portland, que é responsável por cerca de 5% a 8% da emissão global de CO2. Um destes resíduos industriais é a cerâmica vermelha, proveniente do descarte de olarias. O objetivo geral dessa pesquisa é estudar a aplicação de resíduo cerâmico proveniente de olarias em misturas de solo-cimento para estabilização de um solo laterítico, avaliando a resistência à compressão, o efeito de expansão e contração, o potencial hidrogeniônico, a condutividade elétrica, a microestrutura e a proporção ideal de mistura (solo + resíduo cerâmico + cimento Portland). Os resultados mostram ganho de resistência e menor contração/expansão para as misturas com cimento, em relação ao solo puro. E que mesmo com a substituição de parte do cimento por resíduo cerâmico, a resistência praticamente não se altera, devido a reação pozolânica existente entre a cerâmica e o hidróxido de cálcio, o que é confirmado nos ensaios de pH e condutividade elétrica e por imagens obtidas por meio de microscopia eletrônica de... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The waste generated by industry, agriculture and society is a growing concern. Much research has been carried out to reduce the impact on society and the environment. Several residues have been studied as supplementary cementitious materials to replace part of the amount of cement, contributing to the reduction of landfill areas and also to the reduction of CO2 emissions associated with the production of Portland cement, which accounts for about 5% of 8% of global CO2 emissions. One of these industrial wastes is red ceramics from the disposal of potteries. The general objective of this research is to study the application of different percentages of the mixture of ceramic residue with Portland cement in the stabilization of a lateritic soil, evaluating the compressive strength, expansion and contraction effect, permeability, hydrogenation potential, electrical conductivity, the microstructure and the ideal mixing ratio (soil + ceramic residue + Portland cement). The results show increased strength and lower contraction / expansion for cement additions, relative to pure soil. And even with the replacement of part of the cement by ceramic waste, the strenght is practically unchanged due to the pozzolanic reaction between the ceramic and the calcium hydroxide, which is confirmed in the pH and electrical conductivity tests and the images of scanning electron microscopy.
Mestre
10
Tekin, Ahmet Veli. "Effect Of Coating Materials And Mixture Constituents On The Permeability Of Concrete." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614214/index.pdf.
Full textAbstract:
The improvement in the impermeability of concrete was studied using different methods. The main aim was to investigate impermeability improvement of concrete and to compare these methods. Two different methods were examined to investigate and compare impermeability and strength improvement of concrete by using two different sets of concrete specimens. These methods included the application of coating materials to concrete and the production of concrete using different constituent amounts and types. The first set of concrete specimens was prepared by applying two different coating materials (a coating material including both powder and liquid componentsand a coating material including only a liquid component) on reference concrete specimens separately. The second set of concrete specimens was prepared using different proportions of concrete constituents such as cement, water, steel and plastic fibers, mineral and chemical concrete admixtures. Various tests were conducted on both sets of concrete specimens in order to compare the permeability of concrete specimens. However, some of these tests v were not applied on all of the specimens because of test and material specifications. The tests were used to evaluate compressive strength, water absorption, chloride ion penetration and depth of water penetration under pressure. These test methods were carried out on concrete cube specimens and concrete cores taken from those specimens according to the relevant standards. It was found that the permeability of the concrete specimens decreased significantly when the coating material which was composed of the combination of powder and liquid components was applied on concrete specimens. However, permeability did not decrease significantly for concrete specimens coated with the coating material composed of only a liquid component. Significant improvement in the impermeability of the concrete specimens was observed when the amount of cement was increased, the water-to-cement ratio was decreased, mineral admixtures (silica fume and fly ash) and plasticizers were used. This improvement was associated with densification of the concrete microstructure and reduction in capillary pores as a result of pozzolanic reaction and due to reduction in water-to-cement ratio. Coating materials were determined to be effective for concretes with high permeability prior to coating whereas their effect was less significant for lower-initial permeability concretes. Moreover, the effect of coating materials on permeability differed depending on their chemical compositions. The effect of using steel fibers and plastic fibers for the improvement of concrete impermeability was found to be insignificant.
11
Ataie, Feraidon Farahmand. "Enhancement of agricultural residue ash reactivity in concrete through the use of biofuel pretreatments." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16187.
Full textAbstract:
Doctor of PhilosophyDepartment of Civil Engineering
Kyle A. Riding
The cement industry is an important component in the quest to reduce global greenhouse gas emissions because of vast amounts of cement used annually. Incorporating supplementary cementitious materials (SCMs) into concrete is one alternative to reduce cement production and thereby reduce greenhouse gas emissions. This study investigated three types of agricultural residues, namely corn stover, wheat straw, and rice straw, in addition to bioethanol byproducts as potential resources for SCM production for concrete applications. Pretreatments, commonly used in bioethanol production, were used to improve pozzolanic reactivity of corn stover ash (CSA), wheat straw ash (WSA), and rice straw ash (RSA) in cementitious systems. In the first part of this research, the impact of distilled water and dilute hydrochloric acid pretreatments on pozzolanic reactivity of WSA, RSA, and CSA were studied. Results showed that pretreatments, particularly dilute acid, improved pozzolanic properties of CSA, WSA, and RSA by removing potassium and phosphorous from the biomass prior to ashing. In addition, WSA and RSA were shown to have similar pozzolanic reactivity to that of silica fume. In the second part of this study, suitability of high lignin residue (HLR), a bioethanol byproduct, for SCM production was investigated. It was shown that burning high lignin residue produces HLR ash that is very reactive in cementitious materials and can be used as a reactive SCM in concrete. The impact of each step in the production of bioethanol on the quality of bioethanol byproduct for subsequent burning and use in concrete was also studied. Sodium hydroxide and sulfuric acid pretreatments and enzymatic hydrolysis were used. Results revealed that sodium hydroxide pretreatment of the biomass have negative impact on biomass ash properties for concrete use because sodium hydroxide pretreatment did not remove phosphorous and other crystalline phases out of the biomass. However, sulfuric acid pretreatment of biomass greatly improved ash properties. It was also shown that enzymatic hydrolysis could have beneficial impact on ash properties because, during enzymatic hydrolysis, some phosphorous was leached out of the biomass.
12
Hansen, Débora Magali. "Avaliação das propriedades pozolânicas de um resíduo de cerâmica vermelha para emprego como material cimentício suplementar." Universidade do Vale do Rio dos Sinos, 2016. http://www.repositorio.jesuita.org.br/handle/UNISINOS/5397.
Full textAbstract:
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A destinação final ambientalmente adequada para os resíduos sólidos industriais é uma problemática que veio ganhando maior importância ao longo dos anos. O setor da construção civil consome grandes quantidades de insumos, gerando paralelamente grandes quantidades de resíduos. Quando o assunto é reciclagem de resíduos industriais, o setor da construção civil exerce um papel importante, reciclando resíduos de diversos setores da economia. Tendo em vista a existência do polo cerâmico no Rio Grande do Sul, e totalidade de resíduos de cerâmica vermelha (RCV) resultante desse polo, buscou-se através deste estudo, verificar qual é o percentual de geração de RCV em uma empresa específica, devido a grande variabilidade dos dados apresentados pela literatura. E em paralelo buscou-se avaliar o potencial pozolânico do RCV e comparar o seu desempenho com o metacaulim, material já consagrado como pozolana. Os aglomerantes (cimento CP II-F-32, Ca(OH)2 – P.A., CH-I) e os materiais pozolânicos (RCV e metacaulim) empregados na pesquisa foram caracterizados quimicamente por ensaios de fluorescência de raios X (FRX) e Perda ao Fogo (PF), mineralogicamente por ensaios de difração de raios X (DRX) e fisicamente por ensaios de, granulometria a laser, massa específica e área superficial específica (BET). Além disso, o RCV e o metacaulim foram submetidos a ensaios para determinação do teor de umidade e finura. Para avaliar a atividade pozolânica do RCV e comparar seu desempenho ao metacaulim foram realizados ensaios de condutividade elétrica, termogravimetria e ensaios de resistência à compressão, orientados pelas NBR 5752:2014, NBR 5751:2015 e NBR 15894:2010. Mediante os resultados obtidos, verificou-se que o percentual de geração de RCV na empresa objeto de estudo, com os ensaios de caracterização foi possível verificar que o RCV atende aos requisitos químicos estabelecidos pela NBR 12653:2014. O procedimento de moagem conferiu ao RCV uma granulometria adequada para uso como pozolona. Quanto a atividade pozolânica, verificou-se que o RCV atendeu ao requisito da NBR 12653:2014, no que diz respeito à resistência com o aglomerante Ca(OH)2 P.A., já quando ensaiado com o aglomerante CH-I, o RCV apresentou resistência à compressão consideravelmente superior ao metacaulim. Já nas argamassas moldadas com cimento, o RCV não atingiu o índice de atividade pozolânica (IAP) exigido na NBR 12653:2014, impedindo sua classificação como material pozolânico. Nas argamassas ensaiadas sob as prescrições da NBR 15894:2010, contendo 15% de substituição do cimento pelo RCV, os resultados de resistência à compressão não apresentaram diferenças significativas em relação às argamassas referência, apontando indícios de melhor desempenho em menores teores de substituição. As análises térmicas evidenciaram o consumo de Ca(OH)2 das pastas. As pastas formuladas com 25% de substituição do cimento por metacaulim apresentaram maior consumo de Ca(OH)2 em relação as pastas formuladas com 25% de RCV, evidenciando a atividade pozolânica dos materiais.
The final destination environmentally suitable for industrial solid waste is a problem that came gaining more importance over the years. The construction industry consumes large amounts of supplies, generating parallel large quantities of waste. When it comes to recycling of industrial waste, the construction sector plays an important role, recycling waste from various sectors of the economy. Considering the existence of the ceramic polo at the Rio Grande do Sul, and all red ceramic waste (RCV) resulting from this pole, we sought through this study, find what is the percentage of RCV generation in a specific company due the great variability of the data presented in the literature. And in parallel we sought to evaluate the potential of pozzolan RCV and compare their performance with metakaolin, material already recognized as pozzolan. The binder (cement CP II-F-32, Ca(OH)2 – P.A., CH-I) and pozzolanic materials (RCV and metakaolin) employed in the study were chemically characterized by X-ray fluorescence assays (XRF) and Loss Fire (PF), mineralogically by testing X-ray diffraction (XRD) and physically by tests of laser granulometry, specific gravity and specific surface area (BET). Furthermore, the RCV and metakaolin were subjected to tests for determination of humidity content and fineness. To evaluate the pozzolanic activity of the RCV and compare its performance to metakaolin were performed electrical conductivity tests, thermogravimetry and compressive strength tests, guided by the NBR 5752:2014, NBR 5751:2015 and NBR 15894:2010. From the results obtained, found to the percentage of RCV generation in study subject company with the characterization tests it was verified that the RCV meets chemical requirements of the NBR 12653:2014. The grinding procedure gave the RCV adequate particle size for use as pozolona. As the pozzolanic activity, it was found that the RCV met requirement the NBR 12653:2014 with regard to resistance to Ca(OH)2 P.A. agglomerating, since when tested with CH-I agglomerating, the RCV showed compression resistance the considerably higher than metakaolin. Already in the cast with cement mortar, the RCV has not reached the pozzolanic activity index (IAP) required in NBR 12653:2014 preventing classification as pozzolanic material. In mortars tested under the requirements of NBR 15894:2010, containing 15% replacement of cement by RCV, the compressive strength results showed no significant differences from the reference mortar, indicating better performance indications in lower replacement levels. The thermal analysis showed the consumption of Ca(OH)2 pastes. The pastes formulated with 25% of the cement replaced by metakaolin showed increased consumption of Ca(OH)2 relative pastes formulated with 25% RCV, showing the pozzolanic activity of the materials.
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Ratiarisoa, Rijaniaina. "Valorisation de résidus agroindustriels comme matériaux pour l'habitat et la construction : utilisation de la bagasse dans les liants composés minéraux et les composites." Thesis, Antilles, 2018. http://www.theses.fr/2018ANTI0265/document.
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La présente étude vise à valoriser des résidus agroindustriels comme matériaux pour l’habitat et la construction. Dans ce contexte, les travaux de recherche s’articulent autour de deux axes majeurs : le développement d’un liant alternatif et l’élaboration de matériaux composites à partir de ce liant alternatif et des matériaux végétaux. Deux liants composés utilisant des cendres de bagasse, nommés cendres de bagasse-chaux et ciment-cendres de bagasse ont été étudiés. A partir de ces liants composés, deux types de matériaux composites incluant des matériaux végétaux ont été élaborés : un composite incorporant des granulats de bagasse et de coco et un autre renforcé par des pulpes d’eucalyptus. Les propriétés physiques, chimiques, mécaniques et hydriques de ces matériaux ont été déterminées. Les résultats obtenus montrent que la calcination des cendres de bagasse à 600°C et la sélection des particules de taille inférieure à un diamètre seuil compris entre 45 et 63µm augmentent sa réactivité. Le liant composé cendres de bagasse-chaux est susceptible de développer une résistance à la compression de l’ordre de 39MPa à 28 jours, une valeur supérieure à celle des liants composés matériaux pouzzolaniques-chaux étudiés dans la littérature. Grace à sa faible alcalinité, ce liant composé préserve mieux les matériaux végétaux vis à vis de leur minéralisation et leur fragilisation comparativement au liant à base de ciment. L’incorporation de pulpes cellulosiques dans le liant composé cendres de bagasse-chaux permet d’obtenir des matériaux composites ayant des propriétés à la flexion comparables à celles d’un composite ciment-pulpes cellulosiquesThe present study aims to add value to agroindustrial residues as housing and building materials. In this context, the research works revolve around two main lines: the development of an alternative binder using agroindustrial residues and the production of composite materials from this alternative binder and plant resources. Two composed binder using bagasse ash, named bagasse ash lime and cement-bagasse ash, were optimised and produced. Using these composed binder, two kinds of composite materials including plant resources were produced: one composite developed with vegetable aggregates and another one reinforced with eucalyptus pulps. The physical, chemical, mechanical and hydric properties of these materials were investigated. The results show that the bagasse ash recalcination at 600 °C and the selection of the particles under a diameter limit (between 45 and 63 µm) improve its reactivity. Blended with slaked lime, the composed binder obtained with these parameters is likely to develop a compressive strength higher than 39 MPa at 28 days; this value is higher than the compressive strength of pouzzolanic material and lime based binder studied in the literature. In addition, due to the lower alkalinity of the interstitial solution of this composed binder, related to the lime consumption by the pouzzolanic material, it better protects vegetable materials from mineralization than the binders based on Portland cement. The incorporation of the cellulosic pulps in the composed binder lime-bagasse ash produces composite materials with a similar flexural behaviour as a composite made with cement and cellulosic pulp
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Donatello, Shane. "Characteristics of incinerated sewage sludge ashes : Potential for pozzolanic material in construction products." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512054.
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Іващишин, Ганна Степанівна. "Низькоемісійні змішані цементи та модифіковані бетони і будівельні розчини на їх основі." Diss., Національний університет "Львівська політехніка", 2020. https://ena.lpnu.ua/handle/ntb/53805.
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Sio, Jeanette Dorol. "Influence of Pozzolanic Material in the Conversion and Corrosion Behaviour of Calcium Aluminate Cement." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12694.
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Calcium aluminate cement (CAC) is used as a protective lining to combat attack by microorganisms and their metabolic products on reinforced concrete sewer pipes. CAC corrosion behaviour is related to the conversion process of the aluminate hydrates. Full conversion can result to a 5-8 times increase in corrosion rate. Hence, understanding and controlling the rate and the processes that affect conversion is important in the effective use of CAC as a mitigation strategy against the attack of microorganisms. This study was focussed on the role of the pozzolanic material, i.e. fly ash, in suppressing the conversion of CAC. CAC mortars were prepared with constant water-cement ratio of 0.4 and with fly ash contents of 0%, 5%, and 25% weight. To assess the effectiveness of the fly ash, CAC mortars were cured at high temperatures (80-100oC) in water bath to accelerate conversion. Thermal analysis (TGA), X-Ray diffraction (XRD), and scanning electron microscopy (SEM) with integrated EDS and EBSD system were used to monitor the physical and mineralogical transformation of CAC during the conversion and leaching tests. Our study showed that pozzolanic materials have negative and positive impacts in CAC. Based on thickness loss, addition of fly ash improved the corrosion resistance of CAC. This can be attributed to the increased formation of the stratlingite (C2ASH8) that was found to be resistant to both organic and mineral acids. However, analysis based on weight loss and dissolved Al metal showed that addition of fly ash suppresses early corrosion but later corrosion is increased, which is attributed to greater formation of C3AH6 and greater porosity.
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Claus, Julien. "Investigations on a new high-strength pozzolan foam material." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31804.
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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009.Committee Chair: Doyoyo Mulalo; Committee Member: Will Kenneth; Committee Member: Yavari Arash. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Grist, Ellen. "The implementation of innovative and sustainable construction materials." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619149.
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This research uses a novel construction material (lime-pozzolan concrete) and real-world project (a school) as a vehicle for investigating the implementation or applied-innovation process in construction. The implementation of new technologies at a product-level is recognised to be an antecedent of technological change in the construction industry. A ‘real world’ construction project aiming to implement a novel lime-pozzolan concrete in the field, has been used as a process-tracing case study. Rigorous analysis of this case study project, expressly focusing on project-level communication, has shown the implementation of innovative and sustainable materials to be a complex, socio-technical process. With the aim of identifying opportunities to improve project-level design processes in order to support the uptake of innovation and sustainable solutions, twelve high-level theories have been built on twenty-five emergent themes. Collectively these insights demonstrate that implementation processes, once initiated, are experiential, social, contextual, active, interactive, temporal, intentional and mutually constituted phenomena. On the strength of empirical findings this thesis argues for a radical shift in managerial attention from the outcome of the process to the process itself; specifically focused on the experience of the design team as process participants. Laboratory testing and initial field trials have demonstrated the technical feasibility of producing structural grade lime-pozzolan concretes with 28-day compressive strengths of up to 50MPa. The lime-pozzolan concretes were ternary combinations of hydraulic lime (NHL5), ground granulated blastfurnace slag (GGBS) and silica fume (SF). The use of NHL5 in conjunction with pozzolanic materials has been shown to be a viable ‘low-carbon’ alternative to CEMI or CEMIII/A in certain circumstances, although this work has demonstrated that the potential savings in the embodied CO2 and energy of lime-pozzolan concretes are highly dependent on the boundaries of the analysis. Moreover the potential for lime-pozzolan concrete with a lower still CO2 and energy intensity than any concretes tested to date has been identified.
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Nita, Clovis. "Utilização de pozolanas em compósitos de cimento reforçados com fibras de celulose e PVA." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-24032006-111305/.
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Os compósitos reforçados com fibras naturais são uma opção frente a fibrocimentos com amianto, devido à grande disponibilidade de fibras naturais como as de coco, sisal além das fibras de celulose. Aspectos relacionados com a durabilidade precisam ser melhorados, podendo ser citado a diminuição da resistência das fibras quando em meio alcalino causando a perda de propriedades mecânicas dos compósitos. Uma alternativa a esse problema é o uso de pozolana que irá consumir o hidróxido de cálcio proveniente da hidratação do cimento Portland, resultando em fases hidratadas como o C-S-H e aluminatos de cálcio, contribuindo assim, para a redução da alcalinidade e para o aumento da resistência mecânica. A metodologia adotada consistiu da análise do efeito de ciclos de molhagem e secagem quanto à formação de produtos da hidratação do cimento e da reação pozolânica a partir de formulações de cimento, filler dolomito, pozolana (metacaulim ou sílica ativa) e fibras de PVA (polivinil álcool) e celulose. As pozolanas empregadas foram efetivas no consumo de hidróxido de cálcio, porém não se constatou grandes ganhos mecânicos devido à degradação da matriz, observada em 250 ciclos, causada pela formação de hidróxido de magnésio com caráter expansivo. As hipóteses para a causa da formação de brucita consistem da reação de desdolomitização do filler dolomito ou da hidratação do periclásio que compõe o cimento Portland.Composites reinforced with natural fibers are a good asbestos fibercomposites replacement material, as a result of the great natural fiber avaibility such as coco nut, sisal and cellulose. Durability aspects need to be improved, like the decrease of fiber resistance in alkaline environment causing the loss of mechanical properties of the composites. An alternative way to solve this problem is using pozzolan. It will react with calcium hydroxide formed by Portland cement hydration and will provide hydration phases as C-S-H and calcium aluminate hydrated, which contributes for the alkaline reduction and in an increase of mechanical performance. The methodology analyzes the effect of wet/dry cycles in composites among the hydration of cement and pozzolanic reaction in composite formulation made with cement, dolomite filler, pozzolan (metakaolin or silica fume) and PVA and cellulose fibers. The pozzolans used in this study consumed almost calcium hydroxide, although low mechanical properties were found. The matrix degradation with expansive brucite formation is explained with two hypotheses: dedolomitization reaction from dolomite filler or periclase hydration from Portland cement observed from 250 cycles.
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Over, Derya. "Early Heat Evolution In Natural Pozzolan-incorporated Cement Hydration." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614533/index.pdf.
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Portland cement hydration is an exothermic process. The heat evolved during the hydration process is especially important in mass concrete, and hot and cold weather concreting. Heat of hydration is affected by several factors like chemical composition of cement, fineness of cement and ambient temperature. The major aim of this thesis is to investigate the effect of cement composition and fineness, amount and composition of the fine portion (<45 µ
m) of natural pozzolan-incorporated cement on hydration heat. For this purpose, a portland cement and pozzolan-incorporated blended cements containing different amounts of natural pozzolan (trass) were used. The heat of hydration was measured using isothermal calorimetry. The values of heat of hydration for mixtures with different finenesses containing different amounts of added pozzolan were determined. The results obtained were used to find a correlation between the fineness, composition of cement and heat of hydration. According to this study, pozzolan incorporation in small amounts accelerates hydration. A similar effect was obtained for higher pozzolan amounts. Finer cements react faster and result in higher amounts of early heat evolved compared to coarser cements. In addition, it was found that the sum of the heat of hydration values of fine and coarse portion of cements was less than the total heat of hydration of blended cements. Moreover, a satisfactory correlation could not be established between results of isothermal calorimetry, and adiabatic calorimetry, setting time, and strength.
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Duru, Kevser. "Sulfate Resistance Of Blended Cements With Fly Ash And Natural Pozzolan." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607569/index.pdf.
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Numerous agents and mechanisms are known to affect the durability of a concrete structure during its service life. Examples include freezing and thawing, corrosion of reinforcing steel, alkali-aggregate reactions, sulfate attack, carbonation, and leaching by neutral or acidic ground waters. Among these, external sulfate attack was first identified in 1908, and led to the discovery of sulfate resistant Portland cement (SRPC). Besides SRPC, another way of coping with the problem of sulfate attack is the use of pozzolans either as an admixture to concrete or in the form of blended cements
This study presents an investigation on the sulfate resistance of blended cements containing different amounts of natural pozzolan and/or low-lime fly ash compared to ordinary Portland cement and sulfate resistant Portland cement. Within the scope of this study, an ordinary Portland cement (OPC) and five different blended cements were produced with different proportions of clinker, natural pozzolan, low-lime fly ash and limestone. For comparison, a sulfate resistant Portland cement (SRPC) with a different clinker was also obtained. For each cement, two different mixtures with the water/cement (w/c) ratios of 0.485 and 0.560 were prepared in order to observe the effect of permeability controlled by water/cement ratio.
The performance of cements was observed by exposing the prepared 25x25x285 mm prismatic mortar specimens to 5% Na2SO4 solution for 78 weeks and 50mm cubic specimens for 52 weeks. Relative deterioration of the specimens was determined by length, density and ultrasonic pulse velocity change, and strength examination at different ages. It was concluded that depending on the amount and effectiveness of the mineral additives, blended cements were considered to be effective for moderate or high sulfate environments. Moreover, the cement chemistry and w/c ratio of mortars were the two parameters affecting the performance of mortars against an attack. As a result of this experimental study it was found out that time to failure is decreasing with the increasing w/c ratio and the effect of w/c ratio was more important for low sulfate resistant cements with higher C3A amounts when compared to high sulfate resistant cements with lower C3A amounts.
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Shearer, Christopher R. "The productive reuse of coal, biomass and co-fired fly ash." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52298.
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Stricter greenhouse gas emission limits and renewable energy requirements are expected to further increase the worldwide practices of firing biomass and co-firing biomass with coal, which are both considered more sustainable energy sources than coal-only combustion. Reuse options for the by-products of these processes -biomass ash and co-fired fly ash -remain limited. Therefore, this research examines their use as supplementary cementitious materials (SCMs) in concrete and as precursors for alkali-activated geopolymers.
Toward their potential use as an SCM, after characterizing these ashes assessing their compliance with ASTM C618 requirements, their impact on early-age hydration kinetics, rheology, setting time and permeability was assessed. Furthermore, the pozzolanic reactivity and the microstructural and hydrated phase development of the cement-ash samples were analyzed. The results show that a wood biomass ash sample was not satisfactory for use as an SCM. On the other hand, the findings demonstrate that co-fired fly ashes can significantly improve the strength and durability properties of concrete compared to ordinary portland cement, in part due to their pozzolanicity. Thus, it is recommended that the ASTM C618 standard be modified to permit co-fired fly ash sources that meet existing requirements and any additional requirements deemed necessary to ensure their satisfactory performance when used in concrete.
Toward their potential use in geopolymers, this study characterized the early-age reaction kinetics and rheological behavior of these materials, showing that their exothermic reactivity, plastic viscosity and yield stress are significantly influenced by the activator solution chemistry and other characteristics of the ash. Two co-fired fly ashes were successfully polymerized, with compressive strengths generally highest for ashes activated with solutions with a molar ratio of SiO₂/(Na₂O + K₂O) = 1. The results show that geopolymerization is a viable beneficial reuse for these emerging by-products. Further characterization of these materials by scanning transmission X-ray microscopy analysis revealed the heterogeneity of the aluminosilicate phase composition of the co-fired fly ash geopolymer gel at the nano- to micro-scale.
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Justice, Joy Melissa. "Evaluation of Metakaolins for Use as Supplementary Cementitious Materials." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6936.
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Two metakaolins were evaluated for use as supplementary cementitious materials in cement-based systems. The metakaolins varied in their surface area (11.1 v. 25.4 m2/g), but were quite similar in mineralogical composition. Performance of metakaolin mixtures was compared to control mixtures and to mixtures incorporating silica fume as partial replacement for cement at water-to-cementitious materials ratios of 0.40, 0.50, and 0.60. In this study, the early age properties of fresh concrete and the mechanical and durability properties of hardened concrete were examined. Early age evaluations aimed to determine the reactivity of metakaolin (heat of hydration) and its effect on mixture workability (slump, setting time, unit weight). In addition, three types of shrinkage were monitored in metakaolin-cement systems: chemical, autogenous, and free. Compressive, tensile, and flexural strength and elastic modulus were measured at various concrete ages. The influence of metakaolin addition on durability was assessed through accelerated testing for sulfate resistance, expansion due to alkali-silica reaction, and through rapid chloride permeability measurements.
To further quantify the underlying mechanisms of metakaolin's action, the microstructure of pastes was examined. Calcium hydroxide (CH) content was determined using thermogravimetric analysis and verified using differential thermal analysis. Surface area and pore size distribution were evaluated via nitrogen adsorption. These analyses yielded information about the pozzolanic reactivity of metakaolin, associated CH consumption and pore structure refinement, and resulting improvements in mechanical performance and durability of metakaolin-concretes.
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Fernandes, Ana Júlia Maciel Marinho. "Influência do teor de sílica e alumina no comportamento pozolânico de materiais cimentícios suplementares." Universidade do Vale do Rio dos Sinos, 2018. http://www.repositorio.jesuita.org.br/handle/UNISINOS/7154.
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A utilização de materiais cimentícios suplementares (MCS) na produção de cimento é uma estratégia bastante difundida para diminuição de custos de produção, e pode contribuir para a minimização da emissão de CO2. Estes materiais, ao reagirem com o hidróxido de cálcio (CH), gerado na hidratação do cimento, formam silicatos de cálcio e aluminatos de cálcio hidratados adicionais, contribuindo para o ganho de resistência. Segundo a normativa brasileira, para ser considerado um material pozolânico, o somatório de óxidos de Si, Al e Fe deve ser maior do que 70%. No entanto este requisito deve ser tomado com restrições, pois evidências indicam que somente a fração amorfa dos óxidos pozolânicos é que consomem CH. Diante disto, este trabalho teve por objetivo geral avaliar de forma comparativa a influência da composição química e da fração amorfa dos óxidos pozolânicos na reatividade de materiais cimentícios suplementares. Foram estudados uma cinza volante da combustão do carvão (CV); de um resíduo de cerâmica vermelha (RCV); e de um metacaulim (MK). Os materiais tiveram a granulometria ajustada a fim de se obter um D50 de 4 ± 2 µm, buscando uma menor diferença entre a distribuição granulométrica dos MCS e o pó de quartzo (PQ), empregado para compor um padrão secundário de referência, o que permite isolar o fator consumo de cimento nas análises. Os MCS foram caracterizados por FRX, por granulometria à laser, por adsorção de nitrogênio, por picnometria de gás hélio, e microscopia eletrônica de varredura. Empregou-se também DRX em conjunto com o refinamento de Rietveld, utilizando-se o método do padrão interno para a quantificação de fases. A reatividade dos MCS foi medida pelo método de Fratini, por TG/DTG e por resistência à compressão, em pastas e argamassas. Constatou-se que todos os MCS são reativos. O teor de amorfos totais em geral não explica o consumo de CaO, nem as resistências de argamassas. O teor de alumina amorfa apresenta considerável influência sobre consumo de CH, medido em análise térmica, em relação à pasta com PQ. O emprego de pastas para ensaios de resistência, e o padrão com PQ, permitiu avaliar a contribuição da reação dos MCS para as resistências, e, neste caso o teor de amorfos totais e de Al2O3 amorfa apresentam a mesma tendência de comportamento, quanto maior o teor, maior a resistência. No entanto, esta tendência não foi observada quando o teor de SiO2 é isolado, pois o RCV não segue o mesmo comportamento. Foi observado também que o teor elevado de Fe2O3 do RCV pode ser o responsável pela baixa redução de CaO observada no ensaio de Fratini deste MCS.
The use of supplementary cementitious materials (SCM) in the cement production is an usually strategy to reduce costs, and it can promote the reduce of the CO2 emissions. These materials react with the calcium hydroxide (CH), generated in the cement hydration, forming hydrated calcium silicates and aluminates, contributing for the compressive strength. A pozzolanic material has to have, according the Brazilian Standards, a sum of Si, Al and Fe oxides above 70%. However, this requirement have to be taken in account with caution, as evidences indicate that only the amorphous fraction of the pozzolanic oxides consume CH. The aim of this work is to evaluate in a comparative way the influence of the chemical composition and of the amorphous fase of pozzolanic oxides in the reactivity of supplementary cementitious materials. It was studied a fly ash from coal burning (FA), a fired-clay brick powder (FCP) and a comercial metacaulim (MK). The size distribution of the material was adjusted in order to obtain a D50 of 4 ± 2 µm, in order to adjust the granulometry of the materials with the quartz powder (QP), that was employed in a secondary reference composition. The use of this secondary reference allows to compare the pozzolanic materials mixtures with a reference with the same cement consumption. The SCM were characterized by XRF, by laser granulometry, by nitrogen adsorption method, helium gas pycnometry, and by scanning electronic microscopy. It was also employed XRD associated with Rietveld refinement, using the internal pattern method for phase quantifying. The SCM reactivity was measured by Fratini Method, by TG/DTG and by compressive strength, in cement pastes and mortars. It was found that all SCM are reactions. The total amorphous content in general does not explain the CaO consumption, neither the mortars strength. The amorphous alumina content shows a considerable influence on the CH consume measured by TG, taking as reference the pastes with QP. The use of cement paste for compressive strength tests, as well the reference with QP, allowed to evaluate the contribution of the reactivity of SCM for the strength, and, in this case, the total amorphous content and the amorphous Al2O3 content presented the same tendency of behaviour: as big is the content, as big is the strength. However, this tendency it was not observed when the amorphous SiO2 is isolated, because the FCP does not have the same behaviour. It also was observed that the high content of Fe2O3 in the FCP can be responsable for the low tax of CaO consumption observed in the Fratini method of this SCM.
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Aslan, Ozlem. "Predicting Long Term Strength Of Roller Compacted Concrete Containing Natural Pozzolan By Steam Curing." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607727/index.pdf.
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Roller Compacted Concrete (RCC) is new technology gaining popularity in the recent years due to its low cost, rapid construction, and using opportunity of by-products. RCC is widely used in the world. However, the use of RCC has been restricted to construction of few cofferdams, and limited to local use in dam construction up to date.
In this thesis, two types of cement, two types of natural pozzolan, aggregates with varying gradations, and a type of water reducing chemical admixture were used. Prior to carrying out the tests, the chemical and physical properties of materials were determined. Additionally, steam curing was applied to the test specimens in order to get long term compressive strength at early ages. Differences between steam cured specimens and normal cured specimens have been discussed in the discussion part.
In the study, the results indicate that usage of water reducing chemical admixture improves compressive strength of RCC. Moreover, it is revealed that usage of fine material is essential to obtain desired results since the amount of cementitious materials is considerably low in RCC. Steam curing is known as its property of providing long term compressive strength at early ages. It was observed that application of steam curing in CEM I type cement used RCC mixtures generated expected results. However, in CEM IV type cement used RCC mixtures compressive strength results did not behave in the same manner.
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Bayer, Petr. "Použitelnost ložového popele z vitrifikovaného lignitového uhlí v kompozitních cementech." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-217052.
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Předložená magisterská práce se zabývá možným použitím vitrifikovaného lignitového lóžového popele jako náhrada slinku v kompozitních cementech. Byly zkoumány vlivy přidaného vitrifikovaného lóžového popele, jeho jemnosti, alkalických roztoků a jejich koncentrací. Byly připraveny kompozitní cementy v souladu s normou DIN EN 197 – 1. V těchto cementech bylo nahrazeno 30 % slinku vitrifikovaným lóžovým popelem. Konkrétně byly připraveny kompozitní cementy s vitrifikovaným lóžovým popelem o jemnosti 5549 cm2/g a 8397 cm2/g. Dále byly přidány alkalické roztoky hydroxidů a síranů vždy o dvou různých koncentracích, za účelem stimulace pucolánové a/nebo geopolymerní reakce. Mechanické vlastnosti připravených vzorků byly charakterizovány mechanickým testováním na prizmách s rozměry 40×40×160 mm, jak je specifikováno v normě DIN EN 196 – 1. Byla provedena nedestruktivní měření dynamického elastického modulu a destruktivní testovaní na pevnosti v tlaku a v ohybu. Distribuce velikosti částic a chemická analýza vstupních materiálů byla vykonána pomocí laserové granulometrie a rentgenové fluorescence. U zatvrdlých kompozitů bylo dále zkoumáno po 2 a 28 dnech hydratace fázové složení s využitím metody rentgenové difrakce a mikrostruktura s využitím skenovací elektronové mikroskopie. Výsledky ukázaly, že mechanické vlastnosti jsou nezávislé na množství přidaných alkálií stejně jako na jemnosti přidaného vitrifikovaného lóžového popele. Nicméně, znatelně nižší mechanické pevnosti byly pozorovány pro vzorky, které byly aktivovány hydroxidy, pravděpodobně kvůli brzké tvorbě silikátového hydrogelu. Vzorky aktivované sírany nedosáhly pevností jako referenční malta.
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Chengula, Duwa Hamisi [Verfasser]. "Improving Cementitious Properties of Blended Pozzolan Based Materials for Construction of Low Cost Buildings in Mbeya Region, Tanzania / Duwa Hamisi Chengula." Kassel : Kassel University Press, 2018. http://d-nb.info/115379599X/34.
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Kieling, Amanda Gonçalves. "Influência da segregação no desempenho de cinzas de casca de arroz como pozolanas e material adsorvente." Universidade do Vale do Rio dos Sinos, 2009. http://www.repositorio.jesuita.org.br/handle/UNISINOS/4445.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Com o objetivo de reduzir a geração de resíduos nos processos industriais e agrícolas, bem como melhor reaproveitá-los, seja no próprio processo produtivo ou como matéria-prima na elaboração de outros materiais, tem-se cada vez mais investido em pesquisas para a transformação destes, até então considerados apenas resíduos industriais, em produtos de interesse comercial. Neste sentido, as cascas residuais oriundas do processo de beneficiamento de arroz vêm sendo utilizadas como combustível, visando ao aproveitamento energético. Mediante a queima da casca de arroz é gerada a cinza de casca de arroz composta basicamente de sílica, potencializando o uso deste resíduo em diferentes segmentos industriais. Muitos trabalhos aplicam a cinza de casca de arroz na construção civil, visto que grande parte dessas cinzas apresenta características pozolânicas decorrente da alta concentração de sílica amorfa presente no material. Pesquisas têm demonstrado que estas cinzas também apresentam potencialidade de aplicação como material adsorvente. No entanto, a cinza de casca de arroz apresenta-se, muitas vezes, como um material heterogêneo tanto na sua composição granulométrica quanto na sua composição química. Estas características podem interferir nas aplicações limitando seu aproveitamento. A segregação dos resíduos é uma técnica amplamente aplicada no gerenciamento de resíduos sólidos industriais e pode oportunizar a reciclagem dos materiais segregados. Neste contexto, este trabalho tem como proposta principal contribuir para a valorização do resíduo cinza de casca de arroz como co-produto através da etapa de segregação. Foi estudada a influência da segregação da cinza da casca de arroz nas características fisicoquímicas, bem como no seu desempenho como material pozolânico e adsorvente. As amostras e as frações segregadas foram caracterizadas através de parâmetros físicos (perda ao fogo, massa específica, área superficial, distribuição granulométrica) parâmetros químicos (análise química, difração de raio-X) e parâmetros microestruturais (microscopia eletrônica de varredura com espectro de dispersão de energia-EDS). A atividade pozolânica foi determinada após moagem das amostras e das frações através de ensaios de Pozolanicidade com o cimento e Condutividade Elétrica. Os ensaios de adsorção foram realizados com soluções de Cr(VI). O cromo residual foi quantificado pelo método colorimétrico da 1,5- difenilcarbazida. Resultados obtidos demonstraram que a segregação configura-se numa etapa importante, pois remove impurezas e contaminantes presentes na amostra, bem como origina frações diferentes, evidenciadas nos ensaios de caracterização. Nos ensaios de atividade pozolânica, observou-se que a influência da segregação relaciona-se com o tipo de processo de combustão aplicado para a obtenção da cinza. Nos ensaios de adsorção, observou-se que a segregação influenciou na remoção de cromo hexavalente. O estudo demonstrou, nas condições testadas, a viabilidade do uso de cinza de casca de arroz na adsorção do metal quando ajustados os parâmetros do processo que favoreçam a remoção dos íons de cromo.
The main objective for the industry is to reduce the generation of wastes, or to find better uses to them, such as in the own productive process or as raw material in the elaboration of other materials. Also, a great amount of funds has been invested in researches for the transformation of such wastes, in by-products of commercial interest. In this way, the rice husk from the rice processing have been used as combustible, for producing energy. Rice husk ashes are generated from the rice husk burning, which presents a potential to be used as raw material in the production of several products in different industry sectors. Most of the works apply the rice husk ash in civil construction, because a great part of those ashes present pozzolanic characteristics as a result of their amorphous chemical structure and the high silica content. In fact, between other factors, the pozzolanicity of rice husk ash depends on the thermal process applied to the rice husk during burning. Researches have been demonstrating that the ashes also may be potentiality applied as adsorbent. However, the rice husk ash comes, many times, as a heterogeneous material so much in your particle size distribution as in your chemical composition. These characteristics can interfere in the applications limiting your use. The segregation of the wastes is thoroughly a technique applied in the administration of industrial solid waste and it can guarantee the recycle of the segregated materials. This work has as main objective to contribute for the valorization of the waste rice husk ash as coproduct through the segregation stage. It was studied the influence of the segregation of the rice husk ash, in physical-chemical characteristics, as well as your acting as pozzolanic and adsorbent. The samples and segregated fractions were characterized via physical (fire loss, specific gravity, specific surface area, particle size distribution), chemical (chemical analysis, X Ray diffraction) and microstructural parameters (scanning electronic microscopy with energy dispersion spectroscopy – EDS). The pozzolanic activity was determined after grinding the samples and the fractions via Cement pozzolanic and Electric Conductivity Methods. The adsorption rehearsals were accomplished with Cr(VI) solutions, that was quantified by the colorimeter method using 1,5-difenilcarbazida. Results demonstrated that the segregation became an important step, because removes impurities and contaminants from the samples and also originates fractions with different characteristics. It was observed, in pozzolanic activity, that the influence of the segregation links with the type of applied combustion process for the obtaining of the ash. It was observed, in adsorption rehearsals, that the segregation influenced in the removal of chromium (VI). Adsorption results showed, considering the experimental conditions in this work, the viability of the use of rice husk ash in the adsorption of chromium (VI) when adjusted the process’s parameters that guarantee the removal of chromium.
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Moraes, Maria Júlia Bassan de. "Estudo do potencial da cinza de folha de bambu para sua utilização como material pozolânico e sustentável em matrizes cimentantes /." Ilha Solteira, 2019. http://hdl.handle.net/11449/180946.
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Orientador: Jorge Luís AkasakiResumo: O contexto mundial de preocupação em relação ao meio-ambiente, seu uso desenfreado e a emissão dos gases estufa, principalmente a emissão de dióxido de carbono destacou a importância da pesquisa para se buscar novas alternativas sustentáveis nos meios de produção, dentre eles se encaixa a indústria do cimento Portland. A proposta deste estudo é uma nova alternativa sustentável para a construção civil, estudando a cinza de folha de bambu (CFB) como material pozolânico para ser utilizado como substituição parcial do cimento Portland. A cinza de folha de bambu foi produzida através de um processo de autocombustão sem temperatura controlada, e foi caracterizada física e quimicamente através dos ensaios de Fluorescência de Raio – X (FRX), determinação do teor de sílica amorfa, Difratometria de Raio – X (DRX), Granulometria a Laser, Microscopia Eletrônica de Varredura por Emissão de Campo (FESEM), Espectroscopia de Infravermelho por Transformada de Fourier (FTIR) e Analise Termogravimétrica (TGA). Sua reatividade foi analisada através dos ensaios de condutividade elétrica e pH, ensaio de Frattini e pastas de Cal/CFB e Cimento/CFB, as quais foram submetidas aos ensaios de FTIR, TGA e FESEM. Para avaliar sua influência na argamassa no estado fresco e endurecido, foram realizados os ensaios de índice de consistência e o ensaio de resistência à compressão, comparando-se as argamassas com substituição parcial do cimento à uma argamassa controle, sem adição mineral. Já a influência da ci... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The global context of concern for the environment, its unrestrained use and emission of greenhouse gases, especially the emission of carbon dioxide, highlighted the importance of research to find new sustainable alternatives in the means of production, among them, the Portland cement industry. The proposal of this study is a new sustainable alternative for civil construction, studying bamboo leaf ash (BLA) as pozzolanic material to be used as partial replacement of Portland cement. The bamboo leaf ash was produced by a process of autocombustion without temperature control, and was characterized physically and chemically by means of X - Ray Fluorescence (FRX), determination of the amorphous silica content, X - Ray Diffractometry (XRD), Laser Granulometry, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). The reactivity analysis was carried out by means of electrical conductivity and pH measurements, Frattini analysis and calcium hydroxide / CFB and Cement / CFB pastes, which were assessed by FTIR, TGA and FESEM analysis. In order to evaluate its influence on the mortar in the fresh and hardened states, the tests of consistency index and compressive strength were carried out, comparing mortars with cement partial replacement with a control mortar, without mineral addition. The influence of the ash on durability was analyzed by means of mercury intrusion porosimetry analysis (MIP) and acid ne... (Complete abstract click electronic access below)
Mestre
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Pereira, Adriana Maria. "Avaliação do uso da cinza do bagaço de cana-de-açúcar na produção de aglomerantes ativados alcalinamente /." Ilha Solteira, 2019. http://hdl.handle.net/11449/181173.
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Orientador: Jorge Luís AkasakiResumo: Nos últimos anos, tem havido um crescente interesse em substituir parcialmente ou totalmente o uso do cimento Portland por materiais com baixo impacto ambiental; logo o estudo de aglomerantes ativados alcalinamente obtidos a partir da mistura de um precursor sólido, rico em aluminossilicato, e uma solução alcalina de alta concentração, tem se mostrado uma alternativa viável, uma vez que o consumo de energia e a emissão de CO2 durante a produção dessas matrizes são reduzidas, e ainda, ocorre a possibilidade de inserção de subprodutos agroindustriais, na matriz desses aglomerantes. Assim a presente tese apresenta um estudo de viabilidade do uso da cinza do bagaço de cana-de-açúcar (CBC), subproduto da indústria sucroalcooleira, na produção de aglomerantes ativados alcalinamente. A CBC foi obtida a partir da queima não controlada do bagaço de cana-de-açúcar e apresentou uma composição química predominantemente constituída de dióxido de silício. A cinza foi submetida a ensaios de caracterização física e química, de modo a avaliar a viabilidade do uso da cinza na produção de matrizes ativadas. Os ensaios de caracterização e de reatividade indicaram que a cinza apresenta grande parte da sua sílica no estado cristalino, além de apresentar baixa solubilidade e reatividade pozolânica. Porém, os ensaios térmicos e mecânicos das argamassas e pastas produzidas com a CBC, demostraram que, a CBC apresenta boa reatividade para períodos de cura prolongados, possibilitando o seu uso em matriz... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In recent years, there has been a growing interest in partially or totally replacing the use of Portland cement with materials with low environmental impact; Therefore, the study of alkaline activated binders obtained from the mixture of an aluminosilicate rich solid precursor and a high concentration alkaline solution, proved to be a viable alternative since energy consumption and CO2 emission during production of these matrices are reduced, and also, there is the possibility of insertion of agroindustrial byproducts in the matrix of these binders. Thus, this thesis presents a viability study of the sugarcane bagasse ash (SCBA) use, a by-product of the sugar and alcohol industry, in the production of alkaline activated binders. The SCBA was obtained from the uncontrolled calcination of the sugarcane bagasse and presented a chemical composition predominantly constituted of silicon dioxide. The ash was physically and chemically characterized, in order to assess the viability of the ash use in the production of activated matrices. Characterization and reactivity analysis indicated that ash presents a great part of its silica in the crystalline state, low solubility and pozzolanic reactivity. However, the thermal and mechanical analysis of mortars and pastes produced with SCBA showed that ash presented good reactivity for long curing periods, allowing its use in Portland cement matrices and activated matrices. Two types of systems were analyzed in the activated matrices studies:... (Complete abstract click electronic access below)
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Nakanishi, Erika Yukari. "Cinza residual da queima de biomassa do capim elefante (Pennisetum purpureum) como material pozolânico substituto do cimento Portland." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/74/74131/tde-07102013-094322/.
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O objetivo do presente estudo foi contribuir para a viabilização do uso da cinza de capim elefante em escala laboratorial como uma pozolana ativa em substituição parcial do cimento Portland, através da obtenção e tratamento da cinza e seu estudo em pastas. O trabalho foi desenvolvido em três etapas. Na etapa 1, denominada \"Obtenção da cinza\", foi realizado o estudo das estruturas do capim elefante, que foi separado em folhas, (colmo + bainha) e planta inteira e para análise da cinza de cada parte. Observa-se na cinza que há um teor elevado principalmente, de sílica e potássio, sendo que o teor de sílica é maior na folha, enquanto o de potássio é maior no (colmo + bainha). Na etapa 2, denominada \"Tratamento da cinza\", foram realizados diferentes tratamentos químicos e térmicos no material, com o intuito de diminuir os teores dos íons alcalinos, e, com isso, aumentar a proporção de SiO2 na cinza final. Foram realizados três tratamentos, sendo T1 tratamento no capim elefante antes da queima, com solução ácida, T2 tratamento na cinza de capim elefante com água quente e T3 tratamento também na cinza com solução ácida. Pode-se observar que houve um aumento no teor de sílica nas cinzas após os tratamentos. E por fim, na etapa 3, denominada \"Estudo das pastas\", procurou-se aplicar a cinza com tratamento T3, através da caracterização das pastas. Foram produzidas cinco pastas diferentes, C (somente cimento), CC (cimento - cinza), CS (cimento - sílica ativa), CHC (hidróxido de cálcio - cinza) e CHS (hidróxido de cálcio - sílica ativa). Foram feitos estudos de caracterização dos materiais, como também ensaios para a avaliação das pastas, dentre eles, resistência à compressão e ensaios para análise da hidratação do cimento. A cinza apresentou ser um material reativo. E, para sua aplicação em pasta, pode-se notar que a resistência à compressão da pasta com 20% de cinza não diferiu significativamente da pasta produzida somente com cimento. Pela avaliação de difração de raios X (DRX), observou-se a diminuição dos picos das fases ferrita, aluminato tricálcico, belita e alita, o que é indicativo do processo da reação. Adicionalmente, pela análise de termogravimetria, constatou-se o consumo de portlandita, com o passar do tempo e a formação dos géis de CSH. Com base nos resultados obtidos nas três etapas descritas neste trabalho, pode-se concluir que a substituição parcial do cimento Portland pela cinza de capim elefante como material pozolânico é tecnicamente possível e viável.The aim of this study was to contribute to the use of elephant grass ashes, obtained from laboratory scale, as an active pozzolan in partial replacement of Portland cement, by the production and treatment of these ashes and their evaluation study into pastes. The work was developed in three steps. The step 1, entitled: \"Getting Ash\", was carried out to study the structures of elephant grass, which was separated into leaves, (stem + sheath) and the whole plant, and the ashes of each part were analyzed. It is observed that the ash has high content of silica and potassium, whereas the silica content is higher in the leaf part, while potassium is highest in the (stem + sheath) region. In step 2, entitled \"Treatment of the ash\" there were carried out different thermal and chemical treatments on the material, to reduce the concentration of alkali ions and thereby increase the proportion of SiO2 in the ash. Three treatments were carried out: T1, treatment in the elephant grass before burning, with acid solution; T2, treatment in the elephant grass ash with hot water and; T3, treatment also in the ash with acid solution. It can be observed an increase in the silica content in the ashes after of the treatments. Finally, the step 3 activities, entitled \"Study of pastes\", attempted to apply the ash with T3 treatment, by the characterization of the pastes. Five different pastes were produced, C (cement only), CC (cement - ash), CS (cement - silica fume), CHC (calcium hydroxide - ash) and CHS (calcium hydroxide - silica fume). There were made studies for the characterization of the materials, as well as, the tests for the evaluation of the pastes, such as compressive strength tests and the analyses to measure the hydration of the cement. The ash under consideration showed to be a reactive material. For its application in the paste, it can be noted that the compressive strength of the paste with 20% of the ash did not differ significantly the paste produced with only cement. For the evaluation of X-ray diffraction (XRD), it was observed a decrease of the peaks of the ferrite phases, tricalcium aluminate, alite and belite, which is indicative of the reaction process. In the thermogravimetric analysis, it was observed the consumption of portlandite, in the course of time, and the formation of the CSH. Based on the results obtained in the three steps described in this work, it can be concluded that the partial replacement of Portland cement by elephant grass ash as pozzolanic material is technically possible and viable.
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Unsal, Saglik Asli. "Alkali-silica Rectivity And Activation Of Ground Perlite-containing Cementitious Mixtures." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12611249/index.pdf.
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Perlite is a volcanic mineral. The latest investigations on ground perlite showed that it is suitable for pozzolanic usage. Thus, it is of vital importance especially for countries rich in perlite such as Turkey. The aim of this study is to investigate the advantages and problems associated with using perlite in concrete and to identify accurate methods and amounts of use for producing durable cementitious mixtures. Within the scope of this study, the alkali-silica reactivity of perlite containing cementitious mixtures were compared using four different methods. Expansion mechanism of the mixtures were tried to be understood by measuring the alkalinity of bath waters. In order to cope with early strength decreases caused by perlite addition, activation of the mixtures by chemical and thermal methods were attempted. It was found that chloride containing chemicals are very effective at later ages and sodium containing chemicals are more effective at early ages. Sodiumhydroxide addition to the perlite containing mixtures was found to be detrimental to both the initial and late-age strengths of mortars.
It was concluded that perlite addition generally results in a decrease in alkali-silica expansions. However, the expansion of concrete samples should be investigated comprehensively. Thermal curing at high temperatures resulted in a rapid increase at 1-day strengths, however, for better ultimate strengths lower thermal treatments or no-thermal curing were found to be more effective. Compared to the traditional portland cement concretes, high-volume ground perlite concretes have environmental and economical advantages.
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Rovnaníková, Markéta. "Studium a modelování karbonatace betonu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-233351.
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The corrosion of steel reinforcement is probably the most frequent type of degradation of reinforced concrete structures. Reinforcing bars are protected from corrosion by a thin iron oxide layer which is formed on their surface due to a high alkalinity of the surrounding concrete. Corrosion may start when this layer is destroyed (i) either by chloride ion penetration (when the concentration of dissolved chloride at the depth of the reinforcing steel exceeds a critical value) or (ii) by a reduction in the pH value of pore solution to values below 9.5. Such a reduction in alkalinity is the result of carbonation of the Ca(OH)2 in the concrete mass, i.e. of its reaction with the atmospheric CO2. The main aim of this work is an experimental investigation and modelling of carbonation process. The effect of relative humidity, curing period and replacement of Portland cement by supplementary cementing materials (SCM - fly ash, blast furnace slag and metakaolin) on carbonation process has been studied. Calcium hydroxide content in the presence of SCM and their pozzolanic activities have been also determined. Furthermore, lots of parametric studies and comparison of carbonation models have been provided. The software tools based on the introduced models and considering the input data to be statistically independent random variables have been described and used for other parametric studies.
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Frohard, Fabien. "Durabilité des éco-bétons : impact d'additions cimentaires alternatives sur la corrosion des armatures dans les bétons armés." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1170/document.
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L'utilisation de ressources locales est une des facettes importantes du développement durable dans le secteur de la construction. Plusieurs types de sous-produits sont aujourd'hui à l'étude pour une utilisation dans les bétons en tant qu'addition cimentaire, dans le but de développer des liants basés sur des ressources alternatives. La présente étude cherche à évaluer les performances de quatre types de sous-produits sur les propriétés des bétons armés vis-à-vis de la corrosion. La poudre de verre, les cendres volantes de papeterie, les cendres de boues d'épurations ou les sédiments calcinés présentent une nature minérale compatible avec un milieu cimentaire. Face à la problématique de corrosion des armatures, le béton constitue à la fois un milieu alcalin favorisant la passivité des aciers et une barrière de transport qui limite la pénétration de contaminants au sein de la matrice cimentaire (principalement les chlorures et le dioxyde de carbone). Les additions cimentaires doivent donc permettre aux aciers de développer un état passif et apporter à l'enrobage une densification afin de limiter la pénétration de contaminants jusqu'aux armatures. Les propriétés électrochimiques au contact des additions ont été caractérisées et les propriétés de transfert des bétons face aux chlorures et au dioxyde de carbone ont été étudiées. L'utilisation de ces matériaux n'influe pas particulièrement le comportement des aciers. Toutefois, l'enrobage est d'une importance particulière, à la fois vis-à-vis de la pénétration de chlorures et du dioxyde de carbone, mais aussi sur la cinétique de corrosion des armatures. La réactivité des additions impacte les propriétés de transfert qui contrôlent aussi bien la cinétique de contamination des bétons que le processus de corrosion des armatures dépassivéesThe use of locally available resources is a major concern for construction sector when it comes to sustainable development. In the case of concrete, a variety of by-products is currently being investigated for use as cementitious materials so as to develop concrete made out of alternatives resources. The present study intends to assess the performance of four kinds of by-products on corrosion-related properties in reinforced concrete. Glass powder, paper mill fly ashes, sewage sludge ashes or calcined sediments exhibit a mineral nature compatible with the medium of concrete. In terms of corrosion concerns, the concrete act as an alkaline medium that enable steel passivity and as a transport barrier that limits deleterious elements ingress (mainly chlorides, carbon dioxide). Thus, the use of alternative cementitious materials should enable the passivation of steel and should also provide a densification to the cover in order to limit contaminants ingress toward steel vicinity. The electrochemical properties of steel in contact with cementitious additions were characterized and the transfer properties of concrete were investigated. The use of these materials has an insignificant impact on the behavior of steel. However, the concrete cover has significant influence on both chloride and carbon dioxide ingress as well as on the corrosion kinetic of reinforcement. The reactivity of the cementitious materials impacts the transfer properties which control the kinetic of contamination of concretes and the corrosion process of non-passive steel
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Fazzan, João Victor. "Avaliação da reatividade da cinza do bagaço de cana-deaçúcar em concretos por meio do fator k de eficácia cimentante /." Ilha Solteira, 2017. http://hdl.handle.net/11449/151394.
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Orientador: Jorge Luis AkasakiResumo: Com a vigente expansão dos canaviais brasileiros, um estudo direcionado para os resíduos provenientes da cana-de-açúcar torna-se imprescindível no cenário atual. Neste sentido, pesquisas estão sendo desenvolvidas para a utilização de cinza do bagaço da cana-de-açúcar (CBC) em compósitos cimentícios, sendo que esta cinza é obtida a partir da queima do bagaço que é utilizado como combustível em processos de cogeração de energia. A CBC é predominantemente constituída de dióxido de silício, e esta característica tem conduzido à avaliação da potencialidade pozolânica do material, principalmente em substituição ao cimento Portland. Nos últimos anos, tem havido um crescente interesse em se determinar o que é conhecido como Fator k de Eficácia Cimentante, que corresponde a um número que caracteriza o material pozolânico e determina a equivalência entre este e o cimento, do ponto de vista das características aglomerantes, e o seu consequente resultado no desenvolvimento das resistências mecânicas. O coeficiente de eficácia não é único para cada tipo de material, isto é, depende de algumas variáveis como por exemplo a relação água/cimento, proporção entre cimento e pozolana, idade de cura, entre outros parâmetros. Sendo assim, o objetivo principal deste trabalho é determinar o fator de eficácia cimentante da cinza do bagaço de cana-de-açúcar, em termos de resistência mecânica à compressão de microconcretos e concretos. O estudo do fator k se deu a partir da substituição de cimento Port... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: A specific study related to the reusing of wastes from sugarcane industry is essential nowadays, mainly due to the increasing on the brazilian sugar cane plantations. On this way, several studies have been performed using sugarcane bagasse ash (SCBA) in cementitious composites, where the SCBA was obtained from the energy cogeneration process. Due to the chemical composition of SCBA, mainly silicon, studies related to its use as pozzolanic material in Portland cement binder have been reported. In the last years, the knowledge about factor k, that corresponds to a number characterize a pozzolanic material and determines its equivalence with Portland cement (OPC) from mechanical strength point of view, is increasing. Factor k depends on some variables used in mortars or concretes mixtures such as water/OPC ratio, proportion between OPC and pozzolanic material, curing time, among other parameters. The aim of this work is to assess the factor k of SCBA from mechanical point of view micro-concretes and concretes. The assessment of factor k was performed replacing OPC by SCBA and adding SCBA to the control mixture (without SCBA) for a fixed water/OPC ratio. Phisico-chemical characterization of SCBA and its reactivity on calcium hydroxide/SCBA and OPC/SCBA were assessed on pastes. Conductivity/resistivity and electrical impedance measurements were performed on mortar samples. Pozzolanic reactivity of SCBA could be detected by modifications on the conductivity/resistivity and electric... (Complete abstract click electronic access below)
Doutor
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Pyreňová, Eliška. "Studium vlastností polymery modifikovaných malt využívající pucolánově aktivní materiály." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240307.
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This diploma thesis is focused on the study of the properties of polymer-modified cementitious mortars which using pozzolanic active materials based on amorphous silica. Explores the possibilities of using the recycled glass as a partial replacement of cement in PMM. Properties of mortars are reviewed in mineralogical and technological point of view. For specification of the results were used the analysis RTG, DTA and REM.
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Anjos, Marcos Alyssandro Soares dos. "Adi??o do res?duo de biomassa da cana-de-a??car em pastas para cimenta??o de po?os petrol?feros produtores de ?leos pesados." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12742.
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Previous issue date: 2009-04-02The Potiguar basin has large fields of viscous oil where the used method for recovering is based on vapor injection; this operation is carried out by injecting vapor in the oilwell directly, without the protection of a revetment through thermal insulation, what causes its dilation and, consequently, cracks in the cement placed on the annular, and lost of hydraulic insulation; this crack is occasioned by the phenomenon of retrogression of the compressive resistance due to the conversion of the hydrated calcium silicate in phases calcium-rich, caused by the high temperatures in the wells, subjected to thermal recuperation. This work has evaluated the application of composite pastes with addition of residue of biomass of ground sugar-cane bagasse as anti-retrogression mineral admixture for cementation of oil-wells subjected to thermal recuperation. The addition of the mineral residue was carried out considering a relative amount of 10, 20, 30, 40 and 59% in relation to cement mass, trying to improve the microstructure of the paste, still being developed a reference paste only with cement and a paste with addition of 40% of silica flour - renowned material in the oil industry as anti-retrogression additive. Pozzolanic activity of the ash was evaluated through XRD, TG/DTG, as the resistance to compression, and it was also determined the physical and mechanical behavior of the pastes when submitted to cure at low temperatures (22 and 38? C); besides it was evaluated the behavior of the pastes when submitted to two cycles of cure at high temperature (280?C) and pressure (7 MPa). It was verified that the ash of the sugar-cane biomass presents pozzolanic reaction and has great efficiency in decrease the permeability of the paste by filler effect, as well as that addition of ash in a relative amount of 10, 20 e 30% increases cured compressive resistance at low temperatures. It was also showed that the ash in a relative amount of 40% and 59% has very significant efficiency as anti-retrogression additive, since it prevents the decrease of compressive resistance and forms hydrated calcium silicate type xenotlita and tobermorita which have more resistance and stability in high temperatures
A bacia Potiguar tem grandes campos de ?leo viscoso, onde o m?todo de recupera??o utilizado ? a inje??o de vapor; essa opera??o ? realizada injetando-se vapor diretamente no po?o, sem a prote??o do revestimento atrav?s de isolamento t?rmico, o que provoca a dilata??o do mesmo, provocando assim falhas no cimento colocado no anular, e conseq?entemente, perda do isolamento hidr?ulico, esta falha tem origem no fen?meno de retrogress?o da resist?ncia ? compress?o devido a convers?o do silicato de c?lcio hidratado em fases ricas em c?lcio, provocada pelas elevadas temperaturas nos po?os, sujeitos ? recupera??o t?rmica. O presente trabalho avaliou a aplica??o de pastas comp?sitas com adi??o de res?duos de biomassa do baga?o da cana-de-a??car mo?das como aditivo mineral anti-retrogress?o para cimenta??o de po?os petrol?feros sujeitos a recupera??o t?rmica. A adi??o do res?duo mineral foi realizada teores de 10, 20, 30, 40 e 59% em rela??o a massa do cimento, visando melhorar a microestrutura da pasta, sendo ainda produzidas uma pasta de refer?ncia, apenas com cimento e uma pasta com adi??o de 40% de silica flour material consagrado na ind?stria de petr?leo como aditivo antiretrogress?o. Foram avaliados a atividade pozol?nica da cinza atrav?s de DRX, TG/DTG e resist?ncia ? compress?o, determinando-se tamb?m o comportamento f?sico e mec?nico das pastas submetidas a cura com baixas temperaturas (22 e 38?C), al?m da avalia??o do comportamento das pastas submetidas a dois ciclos de cura a alta temperatura (280?C) e press?o (7 MPa). Verificou-se que a cinza de biomassa da cana apresenta rea??o pozol?nica, tendo grande efici?ncia na diminui??o da permeabilidade da pasta por efeito filler, e que as adi??es de cinza em teores de 10, 20 e 30% aumentam a resist?ncia ? compress?o das pastas curadas a baixas temperaturas. Constatou-se ainda que a cinza em teores de 40% e 59% tem ?tima efici?ncia como aditivo antiretrogress?o, pois evitam a diminui??o da resist?ncia ? compress?o e formam silicato de c?lcio hidratado do tipo xenotlita e tobermorita que se apresentam mais resistentes e est?veis as altas temperaturas
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Guélin-Desfarges, Chantal. "Production de spores de penicillium roqueforti par fermentation en milieu solide sur substrats naturels et synthetiques." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF21101.
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Tu, Geng-Ye, and 塗耕業. "Hydration Characteristic of Cement Paste Blended with Pozzolanic Materials." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/34248824734755988221.
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碩士國立中興大學
土木工程學系所
95
The purpose of this research is to investigate the effects of adding pozzolanic materials on the hydration characteristics of the cement paste. First, for the conditions of varied experimental parameters including water-to-binder ratios(w/b), pozzolanic material replacements and testing ages, the compressive strength tests, the ignited loss analysis, and the MIP porosity measurements were conducted on three series of pastes— ordinary Portland cement (OPC) paste, fly ash-cement (FC) paste and slag-cement (SC) Paste. Second, the effects of experimental variables on compressive strength, non-evaporable water (wn) content, Ca(OH)2 content, degree of pozzolanic reaction and porosity of the three series of pastes were studied. The interaction existing in these variables was also assessed. Finally, the correlations between the results of each test would be analyzed and canvassed. The correlation formula would be further established according to the obtained experiment data. Test results show that, for all series of pastes, with w/b increasing, wn content, Ca(OH)2 content, degree of pozzolanic reaction, degree of cement reaction, and porosity would increase. However, the compressive strength and the gel/space ratio of the pastes would decrease; For pozzolan-cement pastes, the wn content would decrease with the increase of the percentage of cement replaced by pozzolanic material; For OPC pastes, with the increase of age and w/b, the Ca(OH)2 content would increase, but after 28 days, the raising tendency has gradually slowed down. Nevertheless, the Ca(OH)2 content of FC and SC pastes would decrease with the age and the proportion of replacement increasing; The reaction degree of pozzolanic material is in connection with age and w/b. For the same w/b, the reaction degree of slag (14.7~40.3%) is higher than that of fly ash (3.1~28.3%); The porosity of paste would increase with the increase of pozzolanic material replacement. For lower w/b and replacement level, pozzolanic materials would have the better capability of filling pores; The gel/space ratio would decrease with the increase of the replacement of pozzolanic material. For both FC pastes and SC pastes, at the highest replacement level, the reduced extent of gel/space ratio would be significantly higher than that at the other replacement levels; As for the correlations between total pore volume and either compressive strength or gel/space ratio, OPC pastes possess the optimum correlation coefficients (R2 = 0.9242 & 0.8845).
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Wu, A.-Man, and 吳阿滿. "Effect of Pozzolanic Materials on Impedance property of Cement Paste." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/62611132589037844390.
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碩士東南科技大學
防災科技研究所
98
This paper is to study the engineering properties of cement paste with fly ash and slag addition, using AC impedance and Vicat needle penetration. The research including the setting time and the impedance behavior of cement paste incorporating with fly ash and slag is implemented. The results shows that the higher water-to-binder ratio, the higher initial and final setting time of paste; with the increase in fly ash and slag addition, the initial and final setting time of paste increases. At both fixed-frequency (100 Hz and 10 kHz), the impedance value of fly ash paste increases with increasing curing age. The impedance value of slag paste rises during 1-28 days of age; and keeps constant during 28-91 days of age. Before 28-d age, the value of impedance for slag is higher than that of impedance for fly ash paste, but after 28-d age, the value of impedance for fly ash is higher than that of impedance for slag paste. From Nyquist plots of fly ash and slag pastes, the impedance values of fly ash and slag pastes increase with increasing curing age. By equivalent circuit simulation of fly ash and slag pastes, the analysis of equivalent circuit model with interface effect is more accurate than that without interface effect.
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Chao, Yu-En, and 趙譽恩. "The Study on Water-Repellent Property of Concrete with Pozzolanic Materials." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/59449909992585204884.
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碩士東南技術學院
防災科技研究所
96
The object of this research is mainly to study the influence of permeability properties of concrete on pozzolanic materials, and further investigate the relationship of Engineering and permeability properties of concrete. The experimental results show that the concrete with the lower water/cement ratio has a decrease in permeability coefficient. The water/cement ratio is found to be proportional to the compressive strength of concrete and inversely proportional to the Log (K). The w/c concrete of 0.68 has a permeability coefficient of 1.8×10-11cm/s. The change rate of permeability coefficient increases with lower w/c of concrete loaded. With the increase in the permeability coefficient, the surface resistance of concrete decreases.
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Chen, Shih-Cheng, and 陳世政. "Adsorption of Chloride Ions on Major Cement Phases and Pozzolanic Materials." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/cn3ch8.
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碩士國立臺灣科技大學
營建工程系
106
This study explored the adsorption of the chloride ion on the major phases of the Portland cement and the pozzolanic materials. During the study, the major phases of the Portland cement, such as C3S、C2S、C3A、C4AF, and the hydrated phase of ettringite were prepared and immersed in the NaCl solution. Both the changes in the chloride ion concentration and the weight of the specimens were measured so the amount of the adsorption was calculated. Results showed that the adsorption was related to the rate of hydration. The phases that hydrate fast had high adsorption, suggesting that the hydration of the phases effectively induced adsorption. It was also shown that the rate of adsorption was effectively increased by increasing the concentration of the NaCl solution. However, the total adsorption per unit weight remained unchanged, suggesting that only the rate of adsorption rather than the total adsorption was increased by the increased NaCl concentration in the solution. Finally, it was found that the pozzolanic materials had low adsorption. In the presence of the pozzolanic materials, the adsorption of the chloride was supposed to be governed by the Portland cement.
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Tsai, Yen-Kai, and 蔡焱凱. "Burgers Model to simulate the Damping Properties of Concrete adding Pozzolanic Materials." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/3xxya7.
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碩士國立高雄應用科技大學
土木工程與防災科技研究所
102
Material damping ratio is a evaluate of material damping performance indicators, if the concrete structures have good self-damping properties of the impact load, wind and earthquakes have better soothing ability, using Burgers model to predict the mechanical damping properties of concrete pozzolan materials, pozzolanic materials furnace slag, fly ash and silica fume content of 0%, 10%, 20% and 30%, a total of 10 kinds of ratios, age 3 days, 7 days, 28 days and 56 days, the number of research participation have aggregate particle size, pozzolan, content and age, nature of compressive strength, elastic modulus, Poisson’s ratio and damping ratio. Test results indicate that the aggregate particle size affects the damping ratio of the specimen does not contain coarse aggregate will be a test of the body than with coarse aggregate is far greater than the added damping ratio of silica fume concrete with silica fume content will decreased with the increase, the longer the smaller the damping ratio and age; adding fly ash and slag concrete of the damping ratio increases with dosage increases with increasing age and damping coefficient will gradually reduce the phenomenon, which add furnace damp stone, in addition to three days of age and content of 20% to 30% of the age of 7 days, damping ratio even lower than that of pure cement concrete, fly ash, but added damping is higher than than pure cement concrete; add Fly ash can increase the damping ratio of concrete admixtures, among which 30% of the fly ash to replace cement has the highest amount of added damping ratio, showing the concrete adding fly ash concrete will increase the damping effect.
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Su, Hen-Ching, and 蘇恆進. "The Study on Pozzolanic Materials for Control Hydration Temperature of Mass Concrete." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/92464567167813457151.
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碩士國立高雄應用科技大學
土木工程與防災科技研究所
101
The purpose of this research is about the variations of hydration heat in different proportioning between the pure cement concrete and the blended cement which mixed with slag and fly ash. Through those experiments that can be found out the effects of heat controlling by reducing large proportion of cement on mass concrete, and also can compare the intensities. It can be used the automatic thermometer to record the temperatures of iconic mockup of concrete. The mockups were made of 2 sets of pure cement concrete proportioning and one set of pozzolan concrete proportioning. There were four mixes the factories that provided the material for the experiments on the same date to make two bulks of test model with pure cement concrete proportioning and four bulks of test model with pozzolan concrete proportioning at the construction site. Under the same working conditions and imitations, the test result of concrete's quality can be considered as the real practice. And more, In the actual base plate pouring, we can set up an area as a model to measure the variations of the temperature and to compare the differences between both of them, and to increase the quality of the study.
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CHIH-WEI, FANG, and 方志偉. "Effects of Pozzolanic Materials on the Pulse Velocity of High Performance Concrete." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/51386741354305792905.
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碩士國立中興大學
土木工程學系
89
The objective of this paper is to experimentally investigate the effects of pozzolanic materials on the pulse velocity of high performence concrete . A mathematical model for the prediction of high performence concrete pulse velocity is also proposed. The specimens of concrete are prepared with various paste content and water-cement ratios.The influences of paste containing various pozzolanic materials on the concrete pulse velocity and compressive strength are analyzed. The result show that the paste properties on the can significantaly influence the pulse velocity of concrete. The pulse velocity at early age reflects well the variation of the concrete properties,it is therefore meaningful to study the behavior of pulse velocity of concrete at early age. Inaddition , the pulse velocity and compressive strength of concrete has a close relationship. The developed model for predicting the pulse velocity of concrete based on the pulse velocity of coarse-aggregate and mortar is quite acceptable, because the pulse velocity of hardened concrete can be predicted with error less than 2.5% for the ages of concrete large than 7 days.
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Pin, Li, and 李斌. "Research of Engineering Properties on Cement Mortar withDesulfurization Slag and Pozzolanic Materials." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/66588922110455209079.
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碩士正修科技大學
營建工程研究所
103
Desulfurization steelworks slag is solid waste arising from the blast furnace via desulfurizer desulphurization, the annual output of about 250,000 tons, desulfurization slag is a general industrial waste, the Environmental Protection Administration Announcement of "recyclable waste." In this study, desulfurization slag, furnace slag, fly ash and other admixtures replace most of the cement, to find the best ratio in order to reduce consumption and waste of natural resources regeneration, the purpose of recycling. In this study, we desulfurization slag and furnace slag, fly ash and cement into cement mortar test body of data obtained through the compression test to identify the most economical and best compression ratio specification standards. The results of this study show that the desulfurization slag fineness, temperature increase, the early compressive strength better, will affect the amount of desulfurization slag Mortar result, add another bit of ash on the strength of the contribution, adding furnace powder contribute to the strength of the obvious. Keywords : desulfurization slag，admixtures
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Hung, Sheng-Feng, and 洪聖豐. "The effect of the mixture proportion on the reactivity of pozzolanic materials." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/45292225194166638912.
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碩士國立交通大學
土木工程系所
104
The purpose of the research is to find out the best mixture proportion for different reactivities of pozzolan materials. In nowadays of engineering, it’s necessary to use concrete for constructing. With the progress of the times and the technology, the quality requirements of concrete have to be in high level as well. Also, we have to consider the requirements of the economy. Consequently, we often use various mineral admixtures to replace part of cement. Because the mixture of proportion will be different from the requirements of construction, we take one proportion to do the experiment. In this way, it’s more convenient to compare different proportions of pozzolan materials to figure out the best proportion. For the curing environments, we divide relative humidity into 70% and 100% to conduct experiments and compare the results. The experimental items including: compressive strength test, tensile splitting strength test, volume stability test, weight-change determination test, surface electric resistance test, and rapid chloride permeability test. The results show that in these 31 proportions, there are no exactly the best proportion. It has to see the requirements of the engineering. For instance, if the requirement is that the concrete has to be in high compressive strength, then choose high reactive pozzolan materials is the better way. No matter which proportion it is, the relative humidity into 100% is often better than 70%, and the curing days is also important. According to the results of the experiments, the curing days are longer, the results of the experimental data are better. The effect of the reactivity of pozzolan materials for concrete is that, if the reactivity is higher, it’s hydration reaction will get much better and the C-S-H gel it makes will be much more complete. This will have great impact on compressive strength and rapid chloride permeability test.
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Narendra, B. S. "Improvement Of Strength Of Soils At High Water Content Using Pozzolanic Materials." Thesis, 2005. https://etd.iisc.ac.in/handle/2005/1488.
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Narendra, B. S. "Improvement Of Strength Of Soils At High Water Content Using Pozzolanic Materials." Thesis, 2005. http://etd.iisc.ernet.in/handle/2005/1488.
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Hsien-sheng, Peng, and 彭獻生. "Effects of Pozzolanic Materials on the Strength and Workability of Recycled Aggregate Concrete." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/88470251244887583544.
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碩士國立中興大學
土木工程學系
88
Due to lower compressive strength and worser workability of recycled aggregate concrete (RAC), it will be limited in the application of construction. Pozzolanic materials such as fly ash and slag could increase compressive strength and workability when it applies on concrete. In this research the recycled aggregate concretes were produced by using a same water to binder ratio and different replacing percentage of fly ash and slag to cement. The engineering properties of recycled aggregate concrete were investigated to determine the optimum replacing amount and rate of fly ash and slag. Test results show that it could increase the compressive strength and the elastic modulus of RAC to reach the same level with natural aggregate concrete for using 30% of fly ash or 50% of slag replacement. Moreover, the defects of inferior workability and the higher slump loss of recycled aggregate concrete could be greatly improved. So, it could enhance the application of recycled aggregate concrete in construction by using Pozzolanic materials to replace parts of cement.