Dissertations / Theses on the topic 'Blended cements'
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1
Kaya, Ayse Idil. "A Study On Blended Bottom Ash Cements." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612504/index.pdf.
Full textAbstract:
Cement production which is one of the most energy intensive industries plays a
significant role in emitting the greenhouse gases. Blended cement production by
supplementary cementitious materials such as fly ash, ground granulated blast
furnace slag and natural pozzolan is one of the smart approaches to decrease energy
and ecology related concerns about the production.
Fly ash has been used as a substance to produce blended cements for years, but
bottom ash, its coarser counterpart, has not been utilized due to its lower pozzolanic
properties. This thesis study aims to evaluate the laboratory performance of blended
cements, which are produced both by fly ash and bottom ash.
Fly ash and bottom ash obtained from Seyitömer Power Plant were used to produce blended cements in 10, 20, 30 and 40% by mass as clinker replacement materials. One ordinary portland cement and eight blended cements were produced in the laboratory. Portland cement was ground 120 min to have a Blaine value of 3500±
100 cm2/g. This duration was kept constant in the production of bottom ash cements. Fly ash cements were produced by blending of laboratory produced portland cement and fly ash. Then, 2, 7, 28 and 90 day compressive strengths, normal consistencies, soundness and time of settings of cements were determined. It was found that blended fly ash and bottom ash cements gave comparable strength results at 28 day curing age for 10% and 20% replacement. Properties of blended cements were observed to meet the requirements specified by Turkish and American standards.
2
Stundebeck, Curtis J. "Durability of ternary blended cements in bridge applications." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5082.
Full textAbstract:
Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 6, 2007) Includes bibliographical references.
3
Ulker, Elcin. "Comparison Of Compressive Strength Test Procedures For Blended Cements." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612506/index.pdf.
Full textAbstract:
The aim of this thesis is to twofold, in order to demonstrate the variabilities that can be faced within the compressive strength of blended cements, one blended cement namely CEM IV / B (P-V) 32.5N is selected and the 28-day compressive strength is obtained by 16 different laboratories following TS EN 196-1 standard. Later, to show the variabilities that could be faced by different standards, three different cement types were selected and their compressive strengths are determined following two procedures first with TS EN 196-1, later with similar procedure described in ASTM.
The strength of cement is determined by TS EN 196-1 in Turkey that is the same for all types of cements. However, American cement producers use different standards for testing the strength of Portland cement and blended cements. The main difference is the amount of water utilized in producing the cement mortar.
It was observed that for Portland and Portland composite cementsthere is not any significant difference in between the compressive strength results of cement mortars prepared by both methods. However, for pozzolanic cements, there is much deviance in the compressive strength results of cement mortars prepared by TS EN 196-1.
4
Canham, Ian. "The control of alkali silica reaction using blended cements." Thesis, Aston University, 1987. http://publications.aston.ac.uk/9726/.
Full textAbstract:
It has been previously established that alkali silica reaction (ASR) in concrete may be controlled by blending Portland cement with suitable hydraulic or pozzolanic materials. The controlling mechanism has been attributed to the dilution of the cement's alkali content and reduced mobility of ions in concrete's pore solution. In this project an attempt has been made to identify the factors which influence the relative importance of each mechanism in the overall suppression of the reaction by the use of blended cements. The relationship between the pore solution alkalinity and ASR was explored by the use of expansive mortar bars submerged in alkaline solutions of varying concentration. This technique enabled the blended cement's control over expansion to be assessed at given `pore solution' alkali concentrations. It was established that the cement blend, the concentration and quantity of alkali present in the pore solution were the factors which determined the rate and extent of ASR. The release of alkalis into solution by Portland cements of various alkali content was studied by analysis of pore solution samples expressed from mature specimens. The specification for avoiding ASR by alkali limitation, both by alkali content of cement and the total quantity of alkali were considered. The effect on the pore solution alkalinity when a range of Portland cements were blended with various replacement materials was measured. It was found that the relationship between the type of replacement material, its alkali content and that of the cement were the factors which primarily determined the extent of the pore solution alkali dilution effect. It was confirmed that salts of alkali metals of the kinds found as common concrete contaminants were able to increase the pore solution hydroxyl ion concentration significantly. The increase was limited by the finite anion complexing ability of the cement.
5
Ukpata, Joseph Onah. "Durability of slag-blended cements in composite chloride-sulphate environments." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/20968/.
Full textAbstract:
The problem of concrete durability in marine environments remains a major challenge for the construction industry. Chlorides and sulphates from sea water attack both the steel reinforcing bars and the concrete binder respectively. Chloride attack leads to steel corrosion, while sulphate attack leads to the formation of expansive ettringite. These challenges, combined with pressures to reduce CO2 emissions associated with conventional Portland cement production, have encouraged the increasing use of supplementary cementitious materials (SCMs). Ground granulated blast-furnace slag is one of the most widely used SCMs, since it offers the potential for the greatest replacement in cement clinker. However, the effects of chemical composition, temperature, slag loading, curing and exposure conditions, concerning changes to microstructure, mechanical strength and durability performance of slag-blended cements are yet to be fully understood. This situation is worsened in marine environments, by the limited information on the combined attack of concrete by chloride and sulphate. This is important, since these ions co-exist in real marine conditions. The present study combines different experimental techniques to investigate the above stated effects on hydration, microstructure, mechanical and transport properties, including chloride binding, to provide improved understanding to the existing literature. The relationships between hydration, microstructure and durability performance have been highlighted, along with chloride binding. Two slags of different chemical compositions (CaO/SiO2 ratios = 1.05 and 0.94), designated as slags 1 and 2, were each blended with CEM I 52.5R at 30 and 70 wt.% replacements to produce 4 blends. Paste and mortar samples were prepared at a constant w/b ratio of 0.5. Reference samples were prepared at w/c of 0.5 using CEM I 42.5R. The pastes were characterised for chemical and microstructural properties, while mortars were used for investigating mechanical and transport properties. Tests were performed under parallel temperatures of 20 and 38°C to reflect temperate and warm tropical climates. The samples were exposed to combined sodium chloride and sulphate, after curing in water for 7 or 28 days. Hydration kinetics were investigated in paste systems using isothermal conduction calorimetry. Crystalline hydration products and phase assemblages were followed by x-ray diffraction (XRD), complemented with simultaneous thermal analysis (STA), to confirm and quantify the phases formed, including chemically bound water. The degrees of slag and clinker hydration were quantified using scanning electron microscope (SEM), coupled with energy dispersive x-ray (EDX) analysis. SEM-EDX spot analysis was also used to characterise poorly crystalline, calcium silicate hydrate (C-S-H). Microstructural development was followed using SEM backscattered electron (BSE) image analysis. This was also used to quantify the paste porosity, which was then complemented with mercury intrusion porosimetry (MIP). Mechanical properties of mortar samples were investigated using compressive and flexural strengths. Transport properties were investigated using water sorptivity and gas permeability in mortar samples. Chloride penetration profiles and non-steady state diffusivity were investigated in mortar prisms, including free chloride penetration depths, using colorimetric approach. Also, chloride and sulphate penetration profiles were investigated in polished paste samples, using SEM-EDX spot analysis. This included analysis of atomic ratios to identify the phases binding chloride and sulphate, and their intermixing with the C-S-H. Chloride binding with and without the presence of sulphate, were investigated in paste samples. Length and mass change due to sulphate attack were investigated in mortar prisms and cubes respectively. Samples were exposed in combined chloride-sulphate solution by submersion or repeated wetting/drying cycles, for a period of 664 days. The results show a positive influence of elevated temperature for the slag blends, leading to a refined microstructure, improved early age strengths and improved resistance to the transport of fluids, including chloride and sulphate. The presence of the combined salt solution led to increased flexural strength. Transport properties were improved during early stages of exposure to salt solution but worsened over longer periods. The developed multiple regression models reasonably predicted changes in mechanical and transport properties, considering the effects of temperature and slag loading. Length change and mass change reduced significantly at elevated temperature. Also, chloride binding was improved at elevated temperature but decreased in the presence of sulphate. The main phases binding chloride include Friedel’s salt, Kuzel’s salt and C-S-H, while sulphate was bound in ettringite, AFm and C-S-H. Generally, within the period of this study, there was a synergy between chloride and sulphate, as sulphate expansion was reduced, while chloride diffusivity was also reduced at the same time. The greatly improved durability properties of the slag blends at 38°C is significant for their application in warm climates.
6
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.
Full textAbstract:
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.
7
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.
8
Tyrer, Mark. "The Hydration chemistry of blended portland blastfurnace slag cements for radiactive waste encapsulation." Thesis, Aston University, 1991. http://publications.aston.ac.uk/14303/.
Full textAbstract:
Blended Portland-blastfumace slag cements provide a suitable matrix for the encapsulation of low and intermediate level waste due to their inherantly low connective porosity and provide a highly alkaline and strongly reduced chemical environment. The hydration mechanism of these materials is complex and involves several competing chemical reactions. This thesis investigates three main areas: 1) The developing chemical shrinkage of the system shows that the underlying kinetics are dominantly linear and estimates of the activation energy of the slag made by this method and by conduction calorimetry show it to be c.53 kJ/mol. 2) Examination of the soUd phase reveals that caldum hydroxide is initially precipitated and subsequently consumed during hydration. The absolute rate of slag hydration is investigated by chemical and thermal methods and an estimation of the average silicate chain length (3 silicate units) by NMR is presented. 3) The developing pore solution chemistry shows that the system becomes rapidly alkaline (pH 13 - 13.5) and subsequently strongly reduced. Ion chromatography shows the presence of reduced sulphur species which are associated with the onset of reducing conditions. In the above studies, close control of the hydration temperature was maintained and the operation of a temperature controlled pore fluid extration press is reported.
9
Tyrer, Mark. "The hydration chemistry of blended Portland blastfurnace slag cements for radioactive waste encapsulation." Thesis, Aston University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315145.
Full text
10
Oliveira, Morais de Sousa Girão Ana Violeta. "The nanostructure and degradation of C-S-H in Portland and blended cements." Thesis, University of Leeds, 2007. http://etheses.whiterose.ac.uk/712/.
Full textAbstract:
The microstructure and composition of water and KOH activated hardened pastes of commercial neat white Portland cement (WPC) and blends with 30% fly ash (PFA) have been characterised using a multi-technique approach, With particular emphasis on the nature of the C-S-H phase. The neat and fly ash blended pastes were activated with water or a 5M KOH solution and cured for one year at 25'C, one month at 55'C and one month at 85'C. The mean length of the aluminosilicate anion structure of C-S-H (29 Si MAS NMR) increased with age and it was higher in the fly ash blended systems. Formulae were presented for the average structural units in the C-S-H present in the systems analysed by TEM-EDX. SEM micrographs showed that as hydration occurred, the microstructure became denser because outer product C-S-H was formed in the water filled spaces and additional C-S-H resulted from the pozzolanic reaction. The chemical composition of C-S-H could not be determined by SEM-EDX because of intermixing with other phases; TEM-EDX was necessary. Inner product C-S-H morphology was fine and homogeneous and that of outer product C-S-H was fibrillar in the water activated systems and foil-like with alkali activation. Fly ash replacement did not change the morphology of lp and Op C-S-H. Small fully hydrated cement and PFA particles were filled with a less dense lp C-S-H with morphology very similar to the foil-like one. TEM-EDX showed that, in general, the mean Ca/(AI+Si) atomic ratio was lower in the water activated blends than that in the neat cement pastes due to the fly ash reaction. The composition- structure data were discussed in terms of models for the nanostructure of C-S-H. Higher curing temperature accelerated the rate of the cement hydration. The mean length of the aluminosilicate of the C-S-H anions was much higher than that of C-S-H formed at lower temperatures, and it was also higher in the blended pastes than with neat cement. Backscattered electron images showed that the grey level of C-S-H in the systems cured at 55T and 85T was in places quite similar to that of the calcium hydroxide: that is, it was brighter than in pastes cured at lower temperature. SEM also showed that the microstructure of the systems cured at higher temperature exhibited non uniform porosity. Inner product C-S-H with a fine scale, homogeneous morphology, was abundant in all systems cured at 55'C and 85'C. Op C-S-H was generally fibrillar with Nvater, and foil-like with alkali. However, the higher temperature curing did result in coarser fibrillar morphology (water activated systems) than that formed at lower temperatures. The C-S-H gel formed in the commercial WPC-30% PFA blended paste hydrated for one year at 25'C and water leached for twelve weeks was also characterised in this work. A matrix effect was clearly observed by 29 Si MAS NMR. Cross-linking of the aluminosilicate anion structure of C-S-H occurred after leaching the sample for four weeks. Formulae were also presented for the average structural units in the C-S-H present in the unleached and four weeks water leached systems analysed by TEM-EDX. lp C-S-H morphology was fine and homogeneous and Op C-S-H had fibrillar morphology. There were many areas in the microstructure of the leached sample where Op C-S-H with foil-like morphology coexisted with fibrillar Op C-S-H.
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Delibas, Tughan. "Effects Of Granulated Blast Furnace Slag Trass And Limestone Fineness On The Properties Of Blended Cements." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614072/index.pdf.
Full textAbstract:
The aim of this research was to determine the effects of the fineness of different mineral additives on loss on ignition, heat of hydration, physical, mechanical and chemical properties of blended cements. For that purpose, portland cement clinker was replaced with granulated blast furnace slag (GBFS), natural pozzolan (NP) and limestone (L) at 6%, 20% and 35% replacement levels. Blended cements containing GBFS and NP were ground to a fineness of 3000, 5000 and 6000 cm2/g. Cements containing L were ground to 3000 cm2/g, 4000 cm2/g and 4500 cm2/g. All of the blended cement types mentioned above were both interground and separately ground to the specified fineness levels. Therefore, a total of 57 different cements were produced. Loss on ignition, heat of hydration, chemical, mechanical and physical analyses were performed on the produced cements. Moreover, the chemical analyses of the cements were obtained for cement particles finer (-45&mum) and coarser (+45&mu
m) than 45 &mu
m in order to determine the ingredients of -45 &mu
m, which is known to be more reactive. As a result it was shown that the grindability differences of the cement ingredients affect the properties of blended cements. An increase in the specific surface area increases both the compressive strength and heat of hydration values and adversely affects the loss on ignition values. The results also showed that if the cement particles were ground finer, it was more prone to moisture which resulted in higher loss on ignition values after longer periods.
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Kurkcu, Mehmet. "Utilization Of Fly Ash From Fluidized Bed Combustion Of A Turkish Lignite In Production Of Blended Cements." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607507/index.pdf.
Full textAbstract:
Fly ashes generated from fluidized bed combustion of low calorific value, high ash content Turkish lignites are characterized by high content of acidic oxides, such as SiO2, Al2O3 and Fe2O3, varying in the range 50-70%. However, there exists no study for the investigation of the possibility of using these ashes as concrete admixture.
Therefore, in this study, characterization of fly ashes from fluidized bed combustion of a Turkish lignite and evaluation of these fly ashes as a substitute for Portland cement in production of pastes and mortars were carried out. The samples were subjected to chemical, physical, mineralogical and morphological analyses. Results of chemical and physical analyses of three fly ash samples show that they satisfy the requirements of EN 197-1, EN 450 and ASTM C 618, except for CaO and SO3, owing to high content of acidic oxides of these ashes contrary to majority of FBC fly ashes reported in the literature. In addition to characterization studies, water requirement, compressive strength, setting time and soundness tests were also performed for 10%, 20% and 30% fly ash-cement blends and the reference cement. Results of these tests reveal that the blends meet compressive strength, setting time and soundness requirements of ASTM C 595 without any pre-hydration treatment, and that fly ashes from fluidized bed combustion of Turkish lignites have significant potential for utilization as an admixture in manufacture of blended cements.
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Sheikh, Vassiem. "Fresh properties, temperature rise and strength development of high strength concrete with binary and tertiary blended cements." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395651.
Full textAbstract:
The use of high strength concrete in the construction industry has become more frequent as both the knowledge of the behaviour of the material and the confidence in its production have increased. An appropriate formulation of materials and mix proportions can result in significantly enhanced performance such as high early strength, reduced heat of hydration and increased durability. As a step towards obtaining optimum performance, an investigation has been carried out on the fresh properties (workability), temperature rise during hydration and strength development. This research was aimed at understanding the role of supplementary cementing materials in binary (OPC+PFA, GGBS, CSF) and ternary (OPC+ CSF/PFA, CSF/GGBS) combinations in these three areas. With respect to workability the use of binary mixes of PFA or CSF reduce the superplasticiser dosage required to obtain a target slump, whereas GGBS increases it. Optimum replacement levels of 10% CSF, 40%PFA+l0%CSF and 60%GGBS+l0% CSF were found at a water/binder ratio of 0.26. Binary mixes of 40% PFA or 60% GGBS reduce the peak semi-adiabatic temperature rise compared to their equivalent OPC mix at 0.26 water/binder ratio. Ternary combinations of 10% CSF with PFA or GGBS have shown significant reductions in peak temperature rise compared to their equivalent binary mixes. Measurement of the in-situ strength by temperature matched curing (TMC) has shown higher early age strengths but lower long term strengths for both binary and ternary mixes compared to cubes cured under standard conditions (20°C). Microstructural evaluation of hardened cement paste indicates that these differences in strength are likely to be associated with stresses generated at the paste/aggregate interface. A novel non-destructive technique to assess the in-situ strength has shown good correlation between conductivity and strength development of high strength concrete.
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Poussardin, Victor. "Utilisation d'argiles et de marnes calcinées dans le développement de ciments composés." Electronic Thesis or Diss., Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0040.
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L’utilisation de Supplementary Cementitious Materials (SCMs) en substitution du clinker est une technologie aujourd’hui bien connue qui permet de réduire le coût environnemental du ciment. Parmi les SCMs largement utilisés on retrouve les cendres volantes, les laitiers de hauts fourneaux ou encore la poudre de verre. Dans les dernières années, un intérêt grandissant s’est développé pour l’utilisation d’argiles calcinées comme ajouts cimentaires, notamment du fait de leur forte réactivité et leur grande disponibilité. Ce projet de thèse s’intéresse à l’utilisation d’argiles et de marnes calcinées comme ajouts cimentaires. L’objectif principal est d’identifier de nouveaux échantillons susceptibles de présenter un intérêt pour une utilisation comme SCMs. Pour ce faire, une approche multi-échelle macro et micro est utilisée afin d’étudier de manière précise la calcination, la réactivité pouzzolanique et le comportement en système cimentaire de ces nouveaux échantillons. Il a été possible de démontrer que les marnes (malgré leur composition minéralogique complexe) présentent un potentiel d’utilisation comme ajout cimentaire après calcination, et ce, même avec une faible proportion d’argiles. Par la suite, il a été démontré que la palygorskite est une argile à haut potentiel pour une utilisation comme ajout cimentaire après calcination, et peut être considérée comme une alternative viable au métakaolin. L’étude poussée de l’utilisation de palygorskites calcinées comme ajouts cimentaires a également permis d’apporter de nouvelles connaissances fondamentales sur la compréhension des mécanismes impliqués lors de la calcination de ce type de matériauxThe use of Supplementary Cementitious Materials (SCMs) as a substitute for clinker is a well-known technology that can reduce the environmental cost of cement. Among the SCMs widely used today are fly ash, blast furnace slag and glass powder. In recent years, there has been a growing interest in the use of calcined clays as SCMs, particularly due to their high reactivity and availability.This thesis project focuses on the use of calcined clays and marlstones as supplementary cementitious materials. The main aim is to identify new materials that could be of interest for use as SCMs. To this end, a multi-scale macro/micro approach is used to study the calcination, pozzolanic reactivity and performance in cementitious systems of these new materials. It was possible to demonstrate that marlstones (despite their complex mineralogical composition) have the potential to be used as supplementary cementitious materials after calcination, even with a low proportion of clays. Subsequently, it was shown that palygorskite is a high potential clay for use as a supplementary cementitious material after calcination, and can be considered as a viable alternative to metakaolin. The extensive study of the use of calcined palygorskites as SCMs has also provided new fundamental insights into the understanding of the mechanisms involved in the calcination of this type of material
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Saeed, Huda. "Glass powder blended cement hydration modelling." Thèse, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/1900.
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The use of waste materials in construction is among the most attractive options to consume these materials without affecting the environment. Glass is among these types of potential waste materials. In this research, waste glass in powder form, i.e. glass powder (GP) is examined for potential use in enhancing the characteristics of concrete on the basis that it is a pozzolanic material. The experimental and the theoretical components of the work are carried out primarily to prove that glass powder belongs to the "family" of the pozzolanic materials. The chemical and physical properties of the hydrated activated glass powder and the hydrated glass powder cement on the microstructure level have been studied experimentally and theoretically. The work presented in this thesis consists of two main phases. The first phase contains experimental investigations of the reaction of glass powder with calcium hydroxide (CH) and water. In addition, it includes experiments that are aimed at determining the consumption of water and CH with time. The reactivity, degree of hydration, and nature of the pore solution of the glass powder-blended cement pastes and the effect of adding different ratios of glass powder on cement hydration is also investigated. The experiments proved that glass powder has a pozzolanic effect on cement hydration; hence it enhances the chemical and physical properties of cement paste. Based on the experimental test results, it is recommended to use a glass powder-to-cement ratio (GP/C) of 10% as an optimum ratio to achieve the best hydration and best properties of the paste. Two different chemical formulas for the produced GP C-S-H gel due to the pure GP and GP-CH pozzolanic reaction hydration are proposed. For the pure GP hydration, the produced GP C-S-H gel has a calcium-to-silica ratio (C/S) of 0.164, water-to-silica ratio (H/S) of 1.3 and sodium/silica ratio (N/S) of 0.18. However, for the GP-CH hydration, the produced GP C-S-H gel has a C/S ratio of 1.17, H/S ratio of 2.5 and N/S ratio of 0.18. In the second phase of this research, theoretical models are built using a modified version of an existing cement hydration modelling code, "CEMHYD3D", to simulate the chemical reaction of the activated glass powder hydration and glass powder in cement. The modified model, which is referred to as the "MOD-model" is further used to predict the types, compositions and quantities of reaction products. Furthermore, the glass powder hydration data, which is obtained experimentally, is incorporated into the MOD-model to determine the effect of adding glass powder to the paste on the process of cement hydration and resulting paste properties. Comparisons between theoretical and experimental results are made to evaluate the developed models. The MOD-model predictions have been validated using the experimental results, and were further used to investigate various properties of the hydrated glass powder cement paste. These properties include, for example, CH content of the paste, porosity, hydration degree of the glass powder and conventional C-S-H and GP CS- H contents. The results show that the MOD-model is capable of accurately simulating the hydration process of glass powder-blended cement paste and can be used to predict various properties of the hydrating paste.
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Li, Shuangxin. "Carbonation of 20-year-old blended cement pastes." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589003.
Full textAbstract:
This PhD study aims to understand the carbonation mechanism of slag-rich waste forms and consequently benefits assessing the long term efficiency of immobilising waste materials with cementitious disposals. Three phases of experiments had been managed to achieve the aim. The first was an examination of three 20-year-old alkali-activated neat slag pastes. This section supplied the information about the immobilisation mechanism of alkaline metal cations within a cement system. The second was a characterisation of four 20-year-old water- activated slag-bearing pastes with curing at 40°C for the initial five years. This part concerned the effects of aging and heating treatment in cement hydration. The third was the accelerated and gentle testing of the water-activated pastes. The carbonation mechanism was mainly drawn by the micro-structural and nano- structural features of carbonated pastes and comparison to those of hydrated pastes. The obtained experimental data for the alkali-activated pastes confirmed the outstanding suitability of slag for fixing metal cations. It was because the formed C- S-H gel had been verified to be entirely tobermorite-based and possess a high substitution degree of bridging Si tetrahedra by Al tetrahedra. Meanwhile, the main fixation mechanism has been proved to be the incorporation of metal cations into the structure of the C-S-H through balancing the charges caused by the substitution. Thus, the significant incorporation of Ae+ within the structure of the C-S-H could be advantageous of immobilising alkaline cations through charge-balancing. The collapse of the C-S-H structure during carbonation has been observed due to not only decalcification, but also dealumination. Thus, according to the above findings, the carbonation is very likely to negatively affect the fixation of waste materials within cement systems. It was because, along with the extraction of the bridging Al tetrahedra, the charge-balancing cations were not needed and possibly would eventually be released. A conceptual model of carbonation occurring in hardened cement pastes has been proposed at the end of the chapter conclusion. More findings about the efficiency of different activators on hydration and the effects of curing temperature and aging on hydration have been discussed in details in the following chapters.
17
Alp, Baris. "Utilization Of Ggbfs Blended Cement Pastes In Well Cementing." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614683/index.pdf.
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In well cementing, the cement slurry is exposed to the conditions far different than those of ordinary Portland cement (PC) used in construction. After placement, hardened cement paste should preserve integrity and provide zonal isolation through the life of the well. American Petroleum Institute (API) Class G cement is the most common cement type used in various well conditions. Class G cement has a high degree of sulfate resistance which makes it more stable than PC when subjected to the compulsive well conditions. Ground granulated blast furnace slag (GGBFS) blended cement has a long history of use in the construction industry, but is not extensively used in well cementing applications.
This study presents an experimental program to investigate the applicability of CEM I and GGBFS blended cement pastes in the well cementing industry. Class G cement and blends of CEM I and GGBFS with the proportions (80:20), (60:40), (40:60) and (20:80) are prepared with same water/cement ratio (0.44) as restricted for Class G cement in API Specification 10A to be tested. The cement pastes are cured for ages of 1 day, 7 days and 28 days at 80
18
Dyson, Heather Margaret. "Early hydration in binary and ternary blended cement systems." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422065.
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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.
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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.
20
Feng, Chen [Verfasser], and Michael [Akademischer Betreuer] Fiederle. "Investigating the pore structure of blended cement with synchrotron microtomography." Freiburg : Universität, 2015. http://d-nb.info/1119805899/34.
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Brown, Ashley Vannoy. "Cement Stabilization of Aggregate Base Materials Blended with Reclaimed Asphalt Pavement." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1314.pdf.
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Chanda, S. "The mechanical properties of a pulverised fuel ash blended cement paste." Thesis, University of Surrey, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370690.
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Dočkal, Jakub. "Vliv technologie mletí na vlastnosti směsných cementů s pucolánovou složkou." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-239954.
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The aim of this thesis was to summarize and assess the possibility of using recycled glass in the manufacture of blended portland cements. Work was focused on examining the possibilities to improve pozzolanic properties of recycled glass with new milling processes. The formation of agglomerates material during the course of grinding and their subsequent effect on the hydration process of binders has been also examining. Part of the thesis was also focused on grindability of materials and determination of using separate or inters grinding.
24
De, Weerdt Klaartje. "Blended cement with reduced CO2 emission- utilizing the fly ash-limestone synergy." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12038.
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During cement production large amounts of CO2 are emitted, about 1 tonne CO2 per tonne clinker, if no measures are taken. About 40% originates from fuel combustion, grinding and other operations, and 60% from the de-carbonation of limestone to form the clinker phases. One way to reduce these emissions on the short term is by replacing part of the clinker with other materials such as slag, limestone powder, fly ash, silica fume and natural pozzolans. The type of replacement materials used depends on their availability (e.g. amount available, price and transportation) and is therefore dependent on the geographical location of the cement plant. The aim of this study is to contribute to the development of a novel all-round Portland composite cement for the Norwegian market. When this study was started, the cements produced at the Norwegian cement plants were: CEM I Portland cements containing up to 5% limestone powder and CEM II/A-V Portland fly ash cements containing up to 18% fly ash but no limestone powder. In this study, the effect of increasing the replacement levels of the ordinary Portland cement (OPC) (up to 35% replacement), and combining siliceous fly ash (FA) and limestone powder (L) to replace OPC are investigated. Using a combination of fly ash and limestone to replace OPC seems to be better than using only one of them. Limestone powder accelerates the early hydration more than fly ash, but fly ash contributes to strength development at later ages due to its pozzolanic reaction. Additionally a chemical interaction between fly ash and limestone has been observed, first in simplified cementitious system and later also in Portland composite cement. Limestone powder interacts with the AFm and AFt phases formed during the hydration of OPC. At first, ettringite forms during the hydration of OPC. When all gypsum is consumed, ettringite will react with the remaining aluminates and form monosulphate. In the presence of limestone, hemi- and monocarboaluminate are formed instead of monosulphate. The ettringite does, therefore, not decompose. This leads to higher volume of the hydrates, which on its turn might reduce the porosity and enhance the compressive strength. The effect of limestone powder on OPC is limited due to its low aluminate content. However, when part of the OPC is replaced by fly ash, the fly ash will introduce additional aluminates to the system as it reacts. This will lower the SO3/Al2O3 and increase the AFm/AFt ratio and thereby amplify the impact of limestone powder. These changes in the AFm and AFt phases have been experimentally observed by TGA, XRD and EDX, and predicted using thermodynamic modelling. Only a few percent of limestone powder are required to prevent ettringite from decomposing to monosulphate. The changes in hydration products resulting from these small limestone powder contents coincides with an increase in compressive strength. Replacement of 5% fly ash with 5% limestone powder in a 65%OPC+35%FA cement resulted in a compressive strength increase ranging between 8 and 13% after 28 days of curing. At higher limestone contents the compressive strength decreases again as the additional limestone mainly serves as an inert filler. Replacing 5% of OPC with limestone powder resulted, on the other hand, in a strength reduction or a slight increase up to 4% after 28 days of curing. The beneficial effect of limestone is maximal at 28 days, and reduces slightly upon further curing. It is furthermore valid at 5, 20 and 40°C. However, at 40°C the fly ash reaction is accelerated and over time the fly ash content is more important than the synergetic effect. The observed increase in compressive strength has to be partly due to the chemical interaction described above as an inert filler (crystalline quartz) with a similar psd does not have the same beneficial impact on strength as limestone. Additionally, the presence of limestone powder does not seem to affect the reactivity of OPC and fly ash significantly. The observed effect between fly ash and limestone enables higher replacement levels than when only one of them is used. The applicability of the study is demonstrated by the fact that cement with the optimal composition found in this study (65%OPC+30%FA+5%L) has recently been used in the construction of the Meteorological Centre in Oslo and the Science Centre in the county of Ostfold
25
Gergab, Faisel Ahmed. "The use of corrosion inhibitors for the protection of steel in blended cement concrete." Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/842852/.
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Repairing reinforced concrete structures experiencing corrosion of the reinforcing bars is a problem all too common in today's climate. When corrosion is the result of chloride ion ingress the use of such patch repairs is likely to create more problems than it solves. In recent years there has been a considerable interest in the development of additives and admixtures which reduce or eliminate the ingress of chloride ions into reinforced concrete. One method of increasing the tolerance of reinforced concrete structures to the presence of chloride ions is the application of corrosion inhibitors. Corrosion inhibitors offer a potentially useful means of suppressing chloride-induced corrosion that does not involve removing the concrete. This thesis presents the results of tests on two commercial corrosion inhibitors (one organic and one inorganic) used as an admixed material to the fresh concrete mix and one commercial corrosion inhibitor used as a surface applied material to mature concrete that have been subjected to accelerated chloride-induced corrosion. Specimens of high, good and poor quality concrete made from 100%0pc, 30%GGBS and 25%PFA cement replacement blends have been manufactured in order to assess the influence of the corrosion inhibitors on the fresh and hardened properties of concrete. The corrosion behaviour of steel bars embedded in equivalent concrete mixes were also examined and the ability of both admixed and surface applied inhibitors to retard and suppress corrosion rates was investigated as a function of time, depth cover and concrete quality. It is concluded that both admixed corrosion inhibitors did not have a major effect on the fresh and hardened properties of the various concrete mixes used in this study. It was also concluded that both admixed corrosion inhibitors were successful in delaying the time to corrosion initiation in all OPC and blended cement concrete mixes to various degrees. Over the time scale of this study it was concluded that the surface applied corrosion inhibitor was able to reduce corrosion rates at the reinforcement throughout the cover depths examined. It was also concluded that the penetrating inhibitors have shown higher and faster corrosion reduction rates in poor quality concrete.
26
Jia, Shanshan. "Micro/nano-structural evolution in blended cement paste due to progressive deionised water leaching." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7429/.
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This study investigates the structural evolution of the blended cement pastes at micro-, nano-, and atomic-scale due to environmental factors, such as, water leaching, ageing and curing temperature, with the aid of the analytical techniques, i.e. thermal analysis, XRD, SEM, TEM and SS MAS NMR. The water leaching experiments are performed on the one year old WPC cement paste blended with 30% PFA, as well as 13 years old WPC cement paste blended with 30% and 50% PFA. It is observed that the water leaching induces the phase dissolution and precipitation, e.g. CH, anhydrous cement, AFm and TAH dissolution, C-S-H secondary formation and decalcification, AFt secondary formation and dissolution. The microstructure of the cement paste changes from compact feature to dry cracked land like feature. The Op C-S-H transfers from fine fibrillar or foil-like feature to three dimensional net like feature, and the porosity of Ip C-S-H has increased. The aluminosilicate structure changes from single chain to double chain as the chains have cross-linked across the interlayer. It is also observed with higher replacement of PFA, the leaching speed is slower. Additionally, it is observed the chemical composition, the micro- and nano-scale structure evolve with ageing. The effects of curing temperature on OPC:BFS blended cement hydration is studied. It is found that as curing temperature increases: the general microstructure of the cement paste becomes more porous; more slag reacts, and more Ip C-S-H with high Al and Mg forms; and the MCL of aluminosilicate anion chain increases. For comparison, synthetic C-A-S-H is also characterized to better understand the structure of the C-A-S-H in the cement paste, especially the atomic-scale structure.
27
Matyk, Tomáš. "Studium vlastností betonů s „green cementy“." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226718.
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The thesis focuses on collecting available information about possible ways of using and usage restriction of portland blended cements and portland cements with limestone for production of concrete. The experimental part of the thesis describes the behavior of portland blended cements and portland cements with limestone in aggressive environments. Furthermore, the thesis concerns the dependence of rheological properties of cement pastes of portland cements and portland cements with limestone on type of plasticizing additives.
28
Jensen, Hans-Ulrich. "The effect of sea-water on the hydration of Portland cement and fly ash cement blends." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47124.
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Stachová, Jana. "Snižování emisí CO2 při výpalu hydraulických pojiv." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-390263.
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The thesis is focused on research and development of hydraulic binders based on FBC-ashes. It examines the possibilities of using this ash in the clinker so that the properties of the final cement are comparable to Portland cement. As an integral part of this thesis the research of emission reduction possibilities in the cement industry - a very current topic these days - is presented.
30
Sirtoli, Davide (ORCID:0000-0003-2717-9509). "Mechanical performance of sulfo-based rapid hardening concrete systems focusing on blends with Portland cement." Doctoral thesis, Università degli studi di Bergamo, 2018. http://hdl.handle.net/10446/104982.
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Calcium sulfoaluminate cement (CSA) represents an eco-friendly alternative to Portland cement (PC) thanks to its low CO2 emission during production. Its main phase is the ye’elimite (C4A3‾S) which reacts with water forming ettringite. This reaction is characterized by the rapidity and the initial high heat production; indeed, CSA is known as a rapid hardening cement. Moreover, the huge ettringite formation during hydration is the main responsible of its performance, like the high early age strength and the low shrinkage evolution. Thanks to its properties, CSA cement was widely used in China during 70’s. However, the lack of bauxite deposits and the consecutive increasing cost of its raw material led to a loss of interest for such systems. Nowadays this interest is regenerated due to the environmental issue. Thus, new solutions are investigated in order to limit the carbon footprint of cement industry, decreasing, at the same time, the economic impact of CSA cement production. A possible solution is represented by blend systems with Portland cement. Such materials combine the PC low cost with the CSA low CO2 emission in systems which maintain the rapid hardening behavior and the long term performance evolution. The main issue for this new material is the lack of knowledge on its behavior, properties and performance in both early and later age, especially for structural applications. This research program has the aim to study a blend system in concrete scale at a CSA/PC ratio of 50/50 comparing its mechanical performance with a CSA and a PC concrete, equal in the 28th day strength class. Eventually, a comparison is done between the collected results for the three investigated systems with the well-known PC constitutive laws reported in the main technical documents. Aspects investigated directly during the campaign are compared with the same aspects calculated by the reported formulations. This comparison defines a first evaluation on the applicability of these already-known formulations in the structural design with CSA based concretes.
31
Martykán, Jiří. "Sledování vývoje AFt fází ve směsných portlandských cementech s fluidním popílkem." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240190.
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Dobrovolný, Petr. "Možnosti využití skelného recyklátu pro přípravu směsných cementů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227741.
Full textAbstract:
This work focuses on the possibility of using recycled glass in the manufacture of blended portland cements. It examines the possibilities to improve pozzolanic properties of recycled glass with new milling processes, the formation of agglomerates material during the course of grinding and their subsequent effect on the hydration process of binders. It is also the optimization of the grinding process with respect to the wear of grinding bodies, grinding energy consumption and maximize the performance of the mill.
33
Snelson, David Geoffrey. "Hydration, pore development and chemical resistance of Metakaolin-fly ash-Portland cement (MK-PFA-PC) blends." Thesis, University of South Wales, 2005. https://pure.southwales.ac.uk/en/studentthesis/hydration-pore-development-and-chemical-resistance-of-metakaolin--fly-ash--portland-cement-mkpfapc-blends(4d662a75-989d-4bb5-9c67-fe6c4c752de4).html.
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The aim of the project is to utilise fly ash (PFA), a waste material/industrial byproduct, with metakaolin (MK), as a partial replacement for Portland cement (PC) in mortar and paste. The influence of various compositions of MK-PFA-PC blends on the resistance to the action of sulphate and synthetic seawater solutions, setting time and heat of hydration will be examined. MK is calcinated clay and is a relatively new pozzolanic material. Although it is a very effective pozzolan it is also very expensive. Using FA, which is a much less expensive material, as a PC replacement material, is problematic, as there is slow and low early strength development whereas MK enhances early strength development. Combining these materials in ternary blends should therefore produce a high performance material at an acceptable cost for use as a pozzolan. However the properties and performance of such a material still need to be fully established. The results of the research show, for the initial and final setting time of binary MK-PC pastes there is a substantial increase at 5% MK and then decreases at 10 and 15% MK before increasing again at 20% MK replacement level. However, with PFA there are different trends to those observed when using MK alone. The initial and final setting time of binary PFA-PC pastes shows a slight increase at 10% PFA and then systematically increases with increase in PFA content up to 40% PFA. Evaluation of sample preparation for porosimetry found that, overall, the compression tested samples show a lower proportion of 'fine pores' (volume (%) 0.05) jam than the cored and cut paste disks. It is deducted that this is due to the widespread microcracking during failure of the cubes under compressive loading thus modifying the pore structure present in the compressive tested samples. In strength development of mortar there is very little advantage in using MK over binary PFA-PC mortar blends when exposed to sulphate solution for up to 2 years. The strength behaviour in seawater is however quite different from that observed in mortar exposed to sulphate solution. As the MK replacement levels increase relative to the PFA levels the resistance to seawater attack improves significantly. In mortar exposed to sulphate solution the durability is greatly improved at high replacement levels in both binary and ternary blends. The durability of mortar exposed to seawater is greatly improved at 30 and 40% total replacement in ternary blended mortars.
34
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.
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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.
35
Trauchessec, Romain. "Mélanges de ciments sulfoalumineux et Portland." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0234/document.
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Les mélanges de ciment sulfoalumineux et de ciment Portland sont des liants hydrauliques innovants permettant de moduler les propriétés des bétons, telles que la vitesse de montée en résistance ou la stabilité dimensionnelle. Les performances du liant peuvent ainsi être ajustées pour de nombreuses applications. Au-delà de cet avantage, les émissions de dioxyde de carbone liées à la production du ciment sulfoalumineux sont significativement réduites comparées à celles du ciment Portland traditionnellement utilisé. La diversité des propriétés de ces liants résulte de la variété des mélanges pouvant être réalisés à partir des deux constituants de base. Chaque mélange présente alors une cinétique d'hydratation et des propriétés qui lui sont propres. Par exemple, certains liants sont expansifs mais présentent une montée en résistance progressive, tandis que d'autres sont stables dimensionnellement alors que leur résistance stagne après quelques jours d'hydratation. L'identification et le contrôle des paramètres à l'origine de ces comportements sont donc nécessaires pour garantir des propriétés spécifiques à un usage donné : chape, mortier de réparation, élément préfabriqué, etc. C'est l'objectif de cette étude qui s'attache à déterminer la cinétique, la minéralogie et les propriétés associées à l'hydratation de trois mélanges contenant 85 %, 70 % et 40 % de ciment Portland. Les essais entrepris ont aussi permis d'aboutir à une modélisation thermodynamique des mécanismes d'hydratation. L'impact de la composition du ciment Portland est également étudié. Enfin, il est montré que l'anhydrite et la chaux sont deux leviers qui modifient radicalement le processus d'hydratation et permettent ainsi d'adapter les propriétés d'un mélange aux exigences de son utilisationBlends of ordinary Portland cement and sulfoaluminate cement are innovative hydraulic binders allowing control of concrete properties such as hardening speed or dimensional stability for specific applications. Moreover, carbon dioxide emissions linked to sulfoaluminate cement are significantly reduced compared to ordinary Portland cement. The binder properties can be adjusted due to the diversity of blends conceivable with these two constituents. Each blend has its own hydration kinetic and properties. For example, some blends are expansive and the hardening is progressive whereas other mixtures are dimensionally stable but their strength stagnates after few days. Identification and control of the parameters responsible of these comportments are necessary in order to guaranty specific properties for each application: screed, repairing mortar, etc. This is the aim of this study which described the hydration kinetic, the properties and composition of three blends containing 85 %, 70 % and 40 % of Portland cement. These experiments are completed by thermodynamic modeling of the hydration mechanisms. The effect of the Portland cement composition has also been tested. Finally, it's shown that anhydrite and calcium hydroxide are two key parameters which modify radically the hydration process and allow the properties adjustment required for the blend used
36
Deschner, Florian [Verfasser], Jürgen [Akademischer Betreuer] Neubauer, Christian [Akademischer Betreuer] Kaps, and Frank [Akademischer Betreuer] Winnefeld. "Reaction of siliceous fly ash in blended Portland cement pastes and its effect on the chemistry of hydrate phases and pore solution / Florian Deschner. Gutachter: Jürgen Neubauer ; Christian Kaps ; Frank Winnefeld." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1054731675/34.
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Stephant, Sylvain. "Etude de l'influence de l'hydratation des laitiers sur les propriétés de transfert gazeux dans les matériaux cimentaires." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS090/document.
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L’utilisation de ciment à haute teneur en laitier est envisagée dans le cadre du conditionnement des déchets nucléaires. Dans ce contexte, il est nécessaire de connaître les propriétés structurales et de transport des gaz formés par la radiolyse de l’eau contenue dans cette matrice. Selon la littérature, ces propriétés sont impactées par l’ajout de laitier de haut-fourneau. L’objectif de cette thèse est de relier les processus d’hydratation des ciments au laitier aux propriétés de transport des gaz. La première partie de cette étude est consacrée à l’étude de l’hydratation des ciments au laitier. La Résonance Magnétique Nucléaire (RMN) du silicium et de l’aluminium a été utilisée pour suivre l’évolution de la quantité des différentes phases anhydres du clinker (C3S, C2S, C3A et C4AF) et des principaux oxydes de la phase vitreuse du laitier (SiO2, Al2O3, MgO et SO3). La quantité de calcium dissoute provenant du laitier a, quant à elle, été déduite en comparant la quantité de portlandite [Ca(OH)2] mesurée par ATG avec celle calculée par un logiciel de spéciation chimique (Phreeqc). Cette approche a permis de déterminer l’évolution du degré d’hydratation des principaux oxydes de la phase vitreuse du laitier dont une dissolution progressive (comparé au clinker) et incongruente (la vitesse de dissolution des différents oxydes et différente) a ainsi pu être mise en évidence. Cette plus faible réactivité du laitier a pu être mise en relation, pour un temps donné, avec la diminution de la quantité d’eau liée au ciment, de la contraction chimique et de la chaleur dégagée. La prise en compte quantitative de la dissolution des phases du clinker et des oxydes du laitier permet une description plus précise de la minéralogie. La deuxième partie de ce travail porte sur l’évolution de la microstructure et de son influence sur les propriétés de transport en phase gazeuse (diffusion et perméabilité). L’évolution du coefficient de diffusion effectif à l’hélium et à l’azote et de la perméabilité intrinsèque a été suivie au cours du temps et comparée à l’évolution de certaines grandeurs, telles que la porosité globale, le diamètre d’entrée critique, la surface spécifique et le degré de connectivité des pores. Les résultats montrent une diminution du coefficient de diffusion effectif et de la perméabilité au cours du temps, ce qui a pu être relié, pour un même matériau, à la diminution de la porosité totale. Une réduction de ces propriétés avec la teneur croissante de laitier a également été observée. Cette baisse est liée à une diminution de la porosité capillaire et à une augmentation de la nanoporosité, due à une modification de la microstructure des C-S-H. La dernière partie de ce projet concerne la relation entre les processus d’hydratation, la microstructure et les propriétés de transport. Dans ce but, des bilans volumiques des réactions d’hydratation ont été réalisés en considérant de façon indifférenciée ou séparée chaque phase du ciment. La prise en compte séparée des différentes phases du ciment permet d’évaluer avec une précision de 10 % la porosité totale, la teneur en eau liée et le volume de contraction chimique. Cette description permet d’expliquer les variations des propriétés de transport d’un même matériau dans la durée. Pour établir ce lien au cours du temps et pour tous les ciments, le volume apparent des C-S-H a été recalculé pour rendre compte de la microstructure de ces hydratesCements with high slag content are currently studied as possible candidate for nuclear waste containment materials. In this context it is important to know their microstructure and the transport properties (permeability and diffusion) of the gases that are formed by the radiolysis of the water present in this material. According to literature, these properties are strongly impacted by the addition of blast furnace slag. The aim of this work is to correlate the hydration processes of slag blended cements with their transport properties. In the first part of this work, the hydration of the slag blended cements, for which only few results have been reported to date, has been studied. Silicon-29 and aluminium-27 Magic-Angle Spinning Nuclear Magnetic Resonance (MAS NMR) were used to follow the variations of anhydrous phases of clinker (C3S, C2S, C3A and C4AF) and of the main oxides of the slag (SiO2, Al2O3, CaO, MgO and SO3). The quantity of calcium dissolved from slag was deduced by fitting the quantity of portlandite [Ca(OH)2] calculated by a geochemical software (PHREEQC - coupled to a thermodynamic database) with TGA measurements. Our approach enabled the evolution of the hydration degree (percentage of reacted material) of various oxides of slag to be determined. A progressive and an incongruent dissolution (the rate of dissolution of the oxides is different) of the slag is observed. The low reactivity of slag could be linked, at a hydration time, to a lower content of bound water, chemical shrinkage and heat of hydration. Quantitatively accounting for the dissolution of clinker and oxide of slag yields a more accurate description of the hydration process. The second part of this work is focused on the microstructure evolution and its influence on the transport properties (diffusion and permeability). Time-evolution of the diffusion coefficients and the intrinsic permeability could be monitored and were then compared to that of the microstructure (global porosity, pore entry size distribution, specific surface area and the degree of connectivity). The results showed a decrease in the diffusion coefficient and permeability over time which is due to the progressive filling of the porosity. A decrease of these parameters with the slag content increasing was also observed. This is a consequence of the diminution of the capillary porosity and augmentation of the nanoporosity resulting from changes in the microstructure of C-S-H. The last part concerns the relation between the hydration processes, the microstructure and the transport properties. To this aim, volumetric balances of reactions involved in the hydration processes were made by considering globally or specifically the hydration of the different phases. Accounting for the hydration of each phase of the cement allowed us to determine the global porosity, the bound water content and the chemical shrinkage with accuracy of the order of 10 %. This description allows the understanding of the transport properties variations in time for a same material To establish this time evolutions for all the cements, the apparent volume of C-S-H was recalculated to account for the microstructure of these hydrates
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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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Zaťko, Petr. "Vliv rozptýlené výztuže na průběh zrání polymercementových hmot." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265336.
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The diploma thesis is focused on polymercement materials with dispersed reinforcement. The aim of this work is development of suitable polymercement mixture and monitoring of the impact of dispersed reinforcement on the course of maturation of these materials and physico-mechanical properties. The effect of high temperatures on the properties of the mortar is also examined. Emphasis is placed on the use of alternative resources and byproducts. Mixed binder of cement and slag and admixture of microsilica was used. Recycled cellulose was used as dispersed reinforcement and was compared with commercial polypropylene fibers.
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Perlot, Céline. "Influence de la décalcification de matériaux cimentaires sur les propriétés de transfert : application au stockage profond de déchets radioactifs." Toulouse 3, 2005. http://www.theses.fr/2005TOU30211.
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Les matériaux cimentaires ont été retenus afin de composer la barrière ouvragée du site français de stockage des déchets nucléaires en formation géologique profonde. Ce choix se justifie par les capacités physico-chimiques propres aux bétons : les hydrates de la matrice cimentaire (CSH) et le pH de sa solution interstitielle contribuent à la rétention des radionucléides ; d'autre part la compacité de ces matériaux limite le transport d'éléments. Il convient de s'assurer de la pérennité de cette structure pendant une durée au moins égale à celle de la vie des déchets (jusqu'à 100 000 ans). Sa durabilité a été éprouvée par l'évolution des propriétés de transfert en fonction de la décalcification de matériaux cimentaires, altération traduisant le vieillissement de l'ouvrage. Deux modes de dégradation ont ainsi été appliqués tenant compte des différentes interactions physico-chimiques induites par la formation hôte. Le premier, de type statique, a consisté en une décalcification accélérée par le nitrate d'ammonium. Il simule l'altération de la barrière ouvragée par les eaux souterraines. La cinétique de la dégradation a été estimée par le suivi du calcium lixivié et l'avancée du front de dissolution de l'hydroxyde de calcium. Pour évaluer l'impact de la décalcification, les échantillons ont été caractérisés à l'état sain puis dégradé, en terme de microstructure (porosité, distribution porosimétrique) et de propriétés de transfert (diffusivité, perméabilité au gaz et à l'eau). L'influence de la nature du liant (CEM I et CEM V/A) et des granulats (calcaires et siliceux) a été observée en répétant les essais sur différentes formulations de mortiers. A cette occasion, une importante réflexion sur la métrologie de cet essai a été menée. Le deuxième mode de dégradation, dynamique, a été réalisé par un perméamètre environnemental. Il recrée les sollicitations subies par l'ouvrage lors de sa phase de resaturation post-fermeture (pression hydraulique imposée par la couche géologique et exothermicité des déchets). Cet appareillage, basé sur le principe d'une cellule triaxiale, permet de fixer un gradient de pression entre 2 et 10 MPa et une température de 20 à 80°C. La variation de la perméabilité à l'eau en fonction de ces deux paramètres expérimentaux, découplés et couplés, a été mesurée et reliée aux modifications microstructurales des échantillonsCementitious materials have been selected to compose engineering barrier system (EBS) of the french radioactive waste deep repository, because of concrete physico-chemical properties: the hydrates of the cementitious matrix and the pH of the pore solution contribute to radionuclides retention; furthermore the compactness of these materials limits elements transport. The confinement capacity of the system has to be assessed while a period at least equivalent to waste activity (up to 100. 000 years). His durability was sustained by the evolution of transfer properties in accordance with cementitious materials decalcification, alteration that expresses structure long-term behavior. Then, two degradation modes were carried out, taking into account the different physical and chemical interactions imposed by the host formation. The first mode, a static one, was an accelerated decalcification using nitrate ammonium solution. It replicates EBS alteration dues to underground water. Degradation kinetic was estimated by the amount of calcium leached and the measurement of the calcium hydroxide dissolution front. To evaluate the decalcification impact, samples were characterized before and after degradation in term of microstructure (porosity, pores size distribution) and of transfer properties (diffusivity, gas and water permeability). The influence of cement nature (ordinary Portland cement, blended cement) and aggregates type (lime or siliceous) was observed: experiments were repeated on different mortars mixes. On this occasion, an essential reflection on this test metrology was led. The second mode, a dynamical degradation, was performed with an environmental permeameter. It recreates the EBS solicitations ensured during the resaturation period, distinguished by the hydraulic pressure imposed by the geologic layer and the waste exothermicity. This apparatus, based on triaxial cell functioning, allows to applied on samples pressure drop between 2 and 10 MPa and temperature from 20 to 80°C. Water permeability evolution relating to experimental parameters, uncoupled or coupled, was relied to mortars microstructural modifications
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"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.
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Chang, Chengcheng, and 張正成. "Engineering Properties of LED Sludge-blended Cement Mortar." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/34307870586889133079.
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碩士國立聯合大學
土木與防災工程學系碩士班
100
The Taiwan government promote the energy saving and carbon reduction policy in recent years, they were encouraged to product Light Emitting Diode (LED) for energy saving. Therefore, the LED sludge a by-product in the LED manufacturing process sludge was been produced largely and may compromise the environment. Since the LED sludge is rich in nano-particles SiO2, Al2O3 and SiC, these hazardous ingredients are harmful to the ecological environment and endanger human health if improper disposal. The purpose of this study is to explore the possibility of using LED sludge and LED-MSWI slag to replace partial cement to mold cement-mortar specimens for test, hence, the research study contained two parts as follow: 1. The LED manufacturing process sludge were calcined and the properties of LED sludge sample were investigated by scanning electron microscope/energy dispersive x-ray spectrometry (SEM/EDS) analysis, x-ray diffraction (XRD) analysis, and Pozzolanic activity index test, the test results were used as a guides for the selections of the particle ize of sludge and replacement ratio for producing compound of sludge-blended cement mortar (SBCM), and then for the compressive strength test, mass growth measurement and MIP test. The compressive strengths of SBCM will be compared with those of OPCM (ordinary Portland cement mortar, control group). 2. The mix of LED sludge with municipal solid waste incinerator (MSWI) ash-mix with 0.5: 1.0 weight ratio were also proposed to be melted and form a glassy slag (called LED-MSWI slag). This slag were conducted for XRD analysis, TCLP test, pozzolanic activity index test, and SEM/EDS analysis, then the LED-MSWI slag is used to replace 5-20 percent of cement by weight in cement mortar specimens (5×5×5-cm3) for compressive strength test, mass growth measurement, XRD analysis, and SEM/EDS analysis. The first part test results revealed that the LED sludge can be replaced partial cement and use in cement mortars,their compressive strength were comparable to the OPCM, because of the nano-particles effect and pozzolanic reaction. The other properties were similar to OPCM. The second part test results exhibit the LED-MSWI slag-blended cement mortar (SBCM) compressive strength substantially greater than OPCM, which was due to nano-particles effect and pozzolanic reaction. The other engineering properties were also similar to OPCM specimens. The goal of this study is to recycle the harmful materials such as LED sludge and MSWI ash-mix into a useful resource to eliminate its disposal problems and appeal to the sustainable development of earth.
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Tzeng, Bor-Yu, and 曾博榆. "Hydration Characteristics of MSWI Ashes Modified Slag Blended Cement." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/84616308271529480885.
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碩士國立中央大學
環境工程研究所
90
This study investigated the pozzolonic reactions and engineering properties of municipal solid waste incinerator (MSWI) ash modified slag blended cements (SBC) with various replacement ratios. The modified slags were characterized by melting the MSWI ash mixtures at 1,400℃ for 30 min. The mixtures were composed of different types of MSWI ash, including fly ash, scrubber ash and bottom ash, with various formulas. Bottom ash and scrubber ash, in general, have higher melting points, and are more energy intensive to melt than fly ash. Therefore, fly ash was used to modify the mixtures. The obtained slags were divided into three series based on the experimental ash mixtures. Following further pulverization, these slags were blended with cement at cement replacement ratios ranging from 10% to 40%. The slags thus obtained were quantified and the characteristics of their SBC pastes examined, including the pozzolanic activity, compressive strength, hydration activity, gel pores, crystal phases, species, and the microstructure at various ages. The results indicate that the slag contained 27∼34% CaO, 29∼39% SiO2, and 8∼23% Al2O3, and approximately 47∼67% non-calcium compounds, thus meeting the ASTM C grade for fly ash, which is similar to that of the blast furnace slag. The 90-day compressive strength developed by SBC pastes with a 10% and 20% cement replacement by slags generated from the modification of scrubber ash, outperformed that of ordinary Portland cement(OPC) by 1-7 MPa, whereas the slags generated from the modifications of bottom ash series were comparable to OPC with a difference of less than 0.5MPa. From the pore size distribution, as shown by the MIP results, it was found that, with increasing curing ages, the gel pores increased and the total porosity and capillary pores decreased ─ a result that shows that hydrates had filled the pores. XRD and DTA species analyses indicated that the hydrates in SBC pastes were mainly CH, the calcium silicate hydrate C-S-H(C-S-H) gel, and C-A-H salts, like those found in OPC paste. TG analysis also indicated that the slag reacted with CH to form C-S-H and C-A-H. The average length (in terms of the number of Si molecules) of linear polysilicate anions in C-S-H gel, as determined by NMR, indicated an increase in all SBC pastes with increasing curing age, which outperformed that of OPC at 90 days. The generation of C-S-H gel, with intersections forming a network structure, as observed by SEM from the surface reaction with CH, also indicated the later development of strength in SBC pastes enhanced by the slag. It can be concluded from the study results that MSWI ash can be modified and processed by melting to recover reactive pozzolanic slag, which may be used in SBC to partially replace cement.
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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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Yu-Hsien, Lin, and 林育賢. "Engineering Properties of White Carbon Sludge-blended Cement Mortar." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/c8qp57.
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碩士國立聯合大學
土木與防災工程學系碩士班
101
The purpose of this study is to explore the possibility of using White Carbon Sludge (WCS) sludge, a by-product from the manufacturing rubber of chemical industry, to replace partial cement in cement-paste, cement-mortar. The emphases are on its material strength and engineering properties. WCS sludge is rich in hazardous nano-particles of SiO2 and other debris of unknown organics. These hazardous ingredients may harmful to the ecological environment, and the WCS sludge may be a pozzlanic material suitable recycling in cement concrete, which worth to investigate. WCS sludge were firstly conducted for XRD analysis and SEM/EDS analysis, the test result demonstrate that the WCS sludge were pozzolanic material, then we adopted the water/cementitious ratio of 0.485 and 0.55, and used 2.5, 5.0, 10.0, and 15.0 % cement replacement to mold the WCS sludge-blended cement mortar (SBCM; experiment group) specimen and ordinary Portland cement mortar (OPCM; control group) specimen are also to be made for comparisons, which are compressive strength test, and mass growth measurement. That test results reveal that the compressive strength of SBCM specimens were comparable to the OPCM specimens by the water/cementitious ratio of 0.485. The compressive strength of SBCM specimens were higher than OPCM specimens about 10~42% by the W/C ratio of 0.55, but their flow values were quickly decrese with the cement replacement ratio increase. For the purpose of practical engineering, which need the good workability . So the experiment try to add the Type G superplastisizer, and we use the Taguchi Method of L9(34). The cement, white carbon sludge, superplasticsizer, and W/C ratios were selected for the control factor, the compressive strength test of 9 samples of SBCM and OPCM specimen were be conducted. The test results reveal that the strength of samples A3B3C2D1 were 154% of OPCM specimens. The reconfirmation test also reveals the good results. Those tests results reveals that the feasibility of reuse WCS sludge in practical engineering. The goal of this study is to transform the waste materials of WCS sludge into a useful resource to eliminate its disposal problems and appeal to the sustainable development of earth.
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"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.
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Chen, Chung-Yuan, and 陳忠元. "Effect of Superplasticizers on the Early Behaivor of Blended Cement." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/08197174833563137839.
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碩士國立中央大學
土木工程學系
86
Superplasticizer(SP)and pozolans, fly ash and slag, are commonlyused in making high performance concrete (HPC) to achieve high flowability and high strength. The flowability and early behavior of freshHPC are highly dependent on the interaction of SP with cement and pozzolans. This research is to investigate the effects of SPs on the earlybehavior of cement paste containing pozzolans. Three SPs including SNF,SMF and PCA were used to study the compatibility with cement, fly ash,and slag. The spread area of minislump test, flow time of Marsh cone,viscosity, adsorption of SP on cement and pozzolan particles, the ion concentration in the solution phase, X-ray diffraction analysis, and SEMobservation were measured in this research.Test results indicate that the saturated concentration of SNF was lower than SMF. The equilibrium time of SNF adsorption on cementparticles was faster than SMF. The slump loss that the SNF added pastewas higher than the paste containing SMF. The adsorption of SNF was amonolayer adsorption. SMF had a maximum amount of adsorption when the concentration was increased to a certain level. The water reducingmechanism of PCA, a polycarboxylic acid based SP, was different from SNF and SMF. A critical dosage of PCA was needed to attain suitable pasteflowability. The use of PCA with fly ash resulted in higher viscosity andhysteresis, the paste became sticky and less flowability. A calcium richhigher SP adsorption. At the same dosage of SP, the flowability was decreased with increasing the amount of fly ash in the paste. The amount ofSP adsorption on slag particle was less than on fly ash. The flowability of the paste containing slag was better than the fly ash added paste.
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Koong, Jan Min, and 孔建民. "Hydration Mechanism of Dry Blended Fly Ash Cement With Steam." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/25725656626607205694.
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碩士國立交通大學
土木工程研究所
82
In 1991 the National Science Council of Republic of China funded a research program, entitled"Hydration Mechanisms and Physical Properties of Cementitious Materials Hardened through The Dry-mix/Steam-Injection Process". The test results indicate that the transfer of heat energy from steam to cement particles at the moment of contact triggers a repid hydration reaction when the activation energy reaches the energy barrier. Concrete thus made developed high strength in relatively short period of time, about one day. It was envisioned that the Pozzolanic materials such as fly ash may have similar behavior as that of the portland cement under the effect of steam. Fly Ash, a by- product of power plants, requires an adequate study for reuses. It generally reacts slowly in Wet process, may however, react rapidly in a pressurized steam condition. The objective of the program is to verify the concept of hydrating the dry fly ash cement by steam. The test results reveal that fly ash concrete made through the dry-mix/steam injection process substantially shortens the hydration time and increases the concrete strength as well. For example, it developed 641 kgf/cm2 strength with a 40% fly ash substitution under a 13.5 hour exposure to 200℃ steam. This report suggests ways to optimize the diffusion mechanisom during the steaming period. The hardened paste of steamed fly ash concrete was examined by the ignition loss process. The result shows that the decomposition phenomenon is quite clear in the temperature range of 105 to 440℃.
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Chen, Kuan-Wei, and 陳冠薇. "Carbonation of Steel-making Slag for CO2 Fixation and Utilization in Blended Cement." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/36475952635977735426.
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碩士國立臺灣大學
環境工程學研究所
103
This study explores the feasibility of developing sustainable construction materials via mineral carbonation of steelmaking slag, i.e., basic oxygen furnace slag (BOFS). The carbon fixation capacity of BOFS was quantified by thermo-gravimetric analysis. Various engineering properties and hydration characteristics of blended cement with 10 % of both fresh BOFS and carbonated BOFS by weight as cement replacement was investigated. The results indicate mineral carbonations accompanied by significant reduction in basicity and fixing 0.202 and 0.221 kg CO2/kg BOFS at 30 oC and 60 oC within the rotating packed bed (RPB) reactor. The reaction kinetics of carbonation experiments could be well expressed by the surface coverage model, with R2 values ranged from 0.97 to 0.98. Cement blended with 10 wt% of carbonated BOFS resulted in reduced setting times and accelerated early strength development, which was consistent with the results of hydration heat and XRD observations. The SEM observations suggest that the carbonated BOFS could serve as nuclei for the precipitation of hydration products, while also accelerating the hydration. In addition, blended cement with 10 % of carbonated BOFS improved sulfate resistance ability and drying shrinkage property compared to 10 % of fresh BOFS at ambient temperature (23oC). The mineralogical composition changes after carbonation have beneficial effects on the hydraulic property in concrete. It was thus concluded that the carbonation of steelmaking slag should be considered as a feasible and attractive process for carbon fixation and waste valorization
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He, Ching-Wei, and 何青薇. "Durability and long-term leachability of cement mortar blended with incinerator bottom ash." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/40603972771423835111.
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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
99
In Taiwan the recovery of incineration bottom ash has usually been used as the construction material. However, the issues of durability and long-term stability are continually worth of research to study on the addition of incineration bottom ash regarding engineering construction products. Thus, this study investigated for the observing the failure behavior of cement mortar under sulfate attack by using the sodium sulfate immersion test and incineration bottom ash on the understanding of heavy-metal leaching characteristic and long-term environmental friendliness by using the Multi-TCLP test. The result of sodium sulfate immersion test showed that the addition of incineration bottom ash below 15% has the ability of corrosion resistance. Moreover, the result of Multi-TCLP test indicated that all metals have no dissolution in the multi-extraction tests but low concentrations of copper and zinc initially. Although incineration bottom ash has the long-term environmental friendliness, the addition of incineration bottom ash used as an aggreagate in the cement motar should be restriction against the risk of corrosion attack.