Journal articles: 'Crystalline admixture'

1

Pazderka, Jiří. "The Crystalline Admixture Effect on Concrete and Cement Mortar Compressive Strength." Key Engineering Materials 722 (December 2016): 87–91. http://dx.doi.org/10.4028/www.scientific.net/kem.722.87.

Full text

Abstract:

There have been many experimental measurements of the waterproofing ability of concrete with a crystalline admixture. For the comprehensive evaluation of crystalline admixtures, it is necessary to consider their effect on the compressive strength of concrete fck, not only their waterproofing ability. The paper describes laboratory testing which subject was the selected crystalline admixtures effect on the compressive strength of concrete fck. The results have shown that the compressive strength fck,cubeof concrete with a crystalline admixture (added in an amount of 2%) was almost identical to the specimens from concrete without admixture after 28 days. The compressive strength of the next specimens from cement mortar with a smaller amount of a crystalline admixture (1%) after the 28 days was higher than the strength of the specimens without admixtures.

APA, Harvard, Vancouver, ISO, and other styles

2

Pazderka, Jiří, and Eva Hájková. "CRYSTALLINE ADMIXTURES AND THEIR EFFECT ON SELECTED PROPERTIES OF CONCRETE." Acta Polytechnica 56, no. 4 (August 31, 2016): 306–11. http://dx.doi.org/10.14311/ap.2016.56.0306.

Full text

Abstract:

There have been many experimental measurements of the waterproofing ability and durability of concrete with a crystalline admixture, but some other important properties have not been reliably tested yet. The results of the tests, carried out by the authors, showed that crystalline admixtures reduce the water vapor permeability of concrete by 16-20 %. The authors also carried out the water pressure test in different time intervals, during the initial phase of cement hydration. The test results have shown that the full waterproofing effect of concrete with a crystalline admixture is available approximately on the 12th day after the concrete creation. The crystalline admixture effect on the compressive strength of concrete was also the subject of the testing. The results have shown that the compressive strength of the concrete with a crystalline admixture (added in an amount of 2 %) and the compressive strength of the specimens from concrete without admixture were almost identical after 28 days.

APA, Harvard, Vancouver, ISO, and other styles

3

García-Vera, Victoria, Antonio Tenza-Abril, José Saval, and Marcos Lanzón. "Influence of Crystalline Admixtures on the Short-Term Behaviour of Mortars Exposed to Sulphuric Acid." Materials 12, no. 1 (December 27, 2018): 82. http://dx.doi.org/10.3390/ma12010082.

Full text

Abstract:

Using durable materials is a sustainable solution for extending the lifetime of constructions. The use of crystalline admixtures makes cementitious materials more durable. They plug pores, capillary tracts and microcracks, blocking the entrance of water due to the formation of crystals that prevent the penetration of liquids. The literature has covered the performance of these admixtures on concrete, but studies on mortars are still scarce. The aim of this study is to investigate the effect of an aggressive environment (sulphuric acid solution—3 wt%) on mortars produced with different percentages of a crystalline admixture (1%, 1.5% and 2% by weight of cement content). Physical and mechanical properties were studied after immersing the mortars in a H2SO4 solution for 90 days. It was found that, after a 90-day sulphuric acid exposure, mortars with the crystalline admixture showed greater compressive strength than the control mortar, besides exhibiting lower mass loss. However, the crystalline admixture did not produce any significant effect on the capillary water absorption coefficient. In a nonaggressive environment, and in the short term, the crystalline admixture did not have a significant effect on the compressive strength, the capillary water absorption coefficient or the ultrasonic pulse velocity.

APA, Harvard, Vancouver, ISO, and other styles

4

Beltrán Cobos, Rubén, Fabiano Tavares Pinto, and Mercedes Sánchez Moreno. "Analysis of the Influence of Crystalline Admixtures at Early Age Performance of Cement-Based Mortar by Electrical Resistance Monitoring." Materials 14, no. 19 (September 30, 2021): 5705. http://dx.doi.org/10.3390/ma14195705.

Full text

Abstract:

Crystalline admixtures are employed for waterproofing concrete. This type of admixtures can affect the early age performance of cement-based mixes. The electrical resistance properties of cement have been related to the initial setting time and to the hydration development. This paper proposes a system for remote monitoring of the initial setting time and the first days of the hardening of cement-based mortars to evaluate the effect of the incorporation of crystalline admixtures. The electrical resistance results have been confirmed by other characterization techniques such as thermogravimetric analysis and compressive strength measurements. From the electrical resistance monitoring it has been observed that the incorporation of crystalline admixtures causes a delay in the initial setting time and hydration processes. The measurements also allow to evaluate the influence of the amount of admixture used; thus, being very useful as a tool to define the optimum admixture dosage to be used.

APA, Harvard, Vancouver, ISO, and other styles

5

Ndoj, Genciana, Armona Kastrati, Erisa Elezi, and Klodjan Xhexhi. "Capacity of Self-Sealing Concrete Embedding Crystalline Admixture." European Journal of Engineering and Technology Research 7, no. 2 (March 30, 2022): 76–80. http://dx.doi.org/10.24018/ejeng.2022.7.2.2762.

Full text

Abstract:

Concrete is one of the most intelligent and widely utilized man-made materials in the construction industry. Despite this, even high-quality concrete is susceptible to porosity, which reduces its serviceability period. Furthermore, there is an increasing need to increase longevity due to environmental exposure such as soil moisture, corrosive outside elements, or structural defects forming in the surface of concrete. The use of crystalline admixtures in concrete is one of the many approaches to reducing these risks. When crystalline admixtures come into contact with water, they form thin crystals that fill pores, capillaries, and micro fractures, as a result making concrete a self-sealing material. When the concrete has dried, the crystalline particles remain dormant until they come into contact with additional water, which causes them to crystallize once more. This research aims to analyze and compare the material properties between commonly used concrete and concrete where crystalline waterproofing is present. Furthermore, experiments are conducted to evaluate each of the concrete samples: compressive strength, water permeability and flexure strength. As a result, demonstrating benefits or negative aspects in the use of crystalline admixture in the early stages of concrete is important. It is not yet defined, weather this is the future of cutting-edge concrete and the impact that it will have in the Albanian building market.

APA, Harvard, Vancouver, ISO, and other styles

6

Žáková, Hana, Jiří Pazderka, and Pavel Reiterman. "Textile Reinforced Concrete in Combination with Improved Self-Healing Ability Caused by Crystalline Admixture." Materials 13, no. 24 (December 18, 2020): 5787. http://dx.doi.org/10.3390/ma13245787.

Full text

Abstract:

The main aim of this study was to investigate the improved autogenous healing of concrete caused by a crystalline admixture in combination with textile reinforced concrete (TRC). This phenomenon (improved healing) has not yet been described by any independent study, and not at all in relation to TRC. The results of the study confirmed that the interaction between TRC and the crystalline admixture’s self-healing ability is advantageous and usable. The application of crystalline admixture could ensure the long-term entirety of the TCR element, where microcracks could occur. This allows for the creation of advantageous, thin (achieved by TRC) and waterproof (achieved by the crystalline admixtures) concrete structures. Moreover, this does not depend on temperature in the range of 4–30 °C (lower temperatures are of course problematic, as for most other cementitious materials). However, the interaction of both materials has its limits; the cracks must not be too wide (max. 0.1 mm), otherwise they will not heal. On the other hand, the advantage is that it does not matter what type of cement is used (CEM I and CEM II showed the same results), and the composition of the newly formed crystals in the cracks corresponds to the composition of the C-S-H gel, so it can be assumed that secondary hydration of the Portland cement occurred in the crack area.

APA, Harvard, Vancouver, ISO, and other styles

7

Hodul, Jakub, Nikol Žižková, and Ruben Paul Borg. "The Influence of Crystalline Admixtures on the Properties and Microstructure of Mortar Containing By-Products." Buildings 10, no. 9 (August 21, 2020): 146. http://dx.doi.org/10.3390/buildings10090146.

Full text

Abstract:

Crystalline admixtures and industrial by-products can be used in cement-based materials in order to improve their mechanical properties. The research examined long-term curing and the exposure to environmental actions of polymer–cement mortars with crystalline admixture (CA) and different by-products, including Bengħisa fly ash and Globigerina limestone waste filler. The by-products were introduced as a percentage replacement of the cement. A crystallization additive was also added to the mixtures in order to monitor the improvement in durability properties. The mechanical properties of the mortar were assessed, with 20% replacement of cement with fly ash resulting in the highest compressive strength after 540 days. The performance was analyzed with respect to various properties including permeable porosity, capillary suction, rapid chloride ion penetration and chloride migration coefficient. It was noted that the addition of fly ash and crystalline admixture significantly reduced the chloride ion penetration into the structure of the polymer cement mortar, resulting in improved durability. A microstructure investigation was conducted on the samples through Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS). Crystals forming through the crystalline admixture in the porous structure of the material were clearly observed, contributing to the improved properties of the cement-based polymer mortar.

APA, Harvard, Vancouver, ISO, and other styles

8

Mircea, Calin, Tudor-Panfil Toader, Andreea Hegyi, Brăduț-Alexandru Ionescu, and Andreea Mircea. "Early Age Sealing Capacity of Structural Mortar with Integral Crystalline Waterproofing Admixture." Materials 14, no. 17 (August 30, 2021): 4951. http://dx.doi.org/10.3390/ma14174951.

Full text

Abstract:

Crystalline admixtures embedded in concrete may react in the presence of water and generate thin crystals able to fill pores, capillaries and micro-cracks. Once the concrete has dried, the crystalline chemicals sit dormant until another dose of water starts the crystallization again. The research aims to analyses the early age self-sealing effect of a crystalline admixture at a dosage rate of 1–3% of the cement mass. Specimens made with two types of gravel were pre-loaded with three-point bending to up to 90% of the ultimate capacity, and conditioned through wet–dry cycles. Micro-crack closure was measured with a microscope after pre-loading, and after 1 day, 4 days, 8 days, 14 days and 20 days of wet–dry exposure. The results show that an admixture content of 3% achieves the best early self-sealing performance. These results are also confirmed by probabilistic analyses, which also emphasize the self-sealing potential of lower ICW contents.

APA, Harvard, Vancouver, ISO, and other styles

9

Krishnaraj, L., P. T. Ravichandran, M. V.A.Karthik, N. Satheeshram Avudaiyappan, and . "A Study on Porous Sealing Efficacy of hydrophilic Admixture on Blended Cement Concrete." International Journal of Engineering & Technology 7, no. 2.12 (April 3, 2018): 446. http://dx.doi.org/10.14419/ijet.v7i2.12.11514.

Full text

Abstract:

The life of the concrete is strongly influenced by durability parameters. The permeability is one of the main characteristics influencing the durability of concrete. The concrete is more permeable due to the ingress of water, oxygen, chloride, sulphate, and other potential deleterious substances. The durability of concrete is mainly affected by pore structure system of concrete and addingthe supplementary cementitious materials (SCM), such as fly ash, slag cement, and silica fume can be decrease permeability. Crystalline technology enhances the strength of concrete by filling the poresand micro-cracks with non-dissolvable substances. To study the efficiency of crystalline formation in concrete in terms of more permeable should be guaranteed through a specific technique.The effectiveness of crystalline waterproofing system with partial replacement cement by GGBS is studiedin terms of strength and durability. The performance of the two different types of crystalline waterproofing integral admixtures has been studied for compressive strength, Split tensile strength, workability, water permeability, Rapid chloride permeability test and porosity in this paper.The early strength increased in GGBS with crystalline admixture concretes compare to the control concrete. No significant strength reduction is observed in GGBS concretes with crystalline admixture when replaced with 20% and 40% of cement than control concrete.

APA, Harvard, Vancouver, ISO, and other styles

10

Pazderka, Jiří, and Eva Hájková. "The Speed of the Crystalline Admixture’s Waterproofing Effect in Concrete." Key Engineering Materials 722 (December 2016): 108–12. http://dx.doi.org/10.4028/www.scientific.net/kem.722.108.

Full text

Abstract:

There have been many experimental measurements of the waterproofing ability and durability of concrete with a crystalline admixture but there are uncertainties about the speed of the waterproofing effect caused by the crystalline admixture. The paper describes water pressure test carried out in different time intervals during the initial phase of cement hydration. The test results have shown that the full waterproofing effect of concrete with a crystalline admixture was available approximately on the 12th day after the concrete creation.

APA, Harvard, Vancouver, ISO, and other styles

11

Azarsa, Pejman, Rishi Gupta, and Alireza Biparva. "Inventive Microstructural and Durability Investigation of Cementitious Composites Involving Crystalline Waterproofing Admixtures and Portland Limestone Cement." Materials 13, no. 6 (March 20, 2020): 1425. http://dx.doi.org/10.3390/ma13061425.

Full text

Abstract:

The durability of a cement-based material is mainly dependent on its permeability. Modifications of porosity, pore-structure and pore-connectivity could have significant impacts on permeability improvement, which eventually leads to more durable materials. One of the most efficient solutions in this regard is to use permeability reducing admixtures (PRA). Among these admixtures for those structures exposed to hydro-static pressure, crystalline waterproofing admixtures (CWA) have been serving in the construction industries for decades and according to ACI 212—chemical admixtures’ report, it has proven its capability in permeability reduction and durability-enhancement. However, there is substantial research being done on its durability properties at the macro level but very limited information available regarding its microstructural features and chemical characteristics at the micro level. Hence, this paper presents one of the first reported attempts to characterize microstructural and chemical elements of hydration products for cementitious composites with CWA called K, P and X using Scanning Electron Microscopy (SEM). Backscattered SEM images taken from a polished-section of one CWA type—K—admixture were analyzed in ImageJ to obtain paste matrix porosity, indicating a lower value for the CWA-K mixture. X-ray analysis and SEM micrographs of polished sections were examined to identify chemical compositions based on atomic ratio plots and brightness differences in backscatter-SEM images. To detect chemical elements and the nature of formed crystals, the fractured surfaces of three different CWA mixtures were examined. Cementitious composites with K admixture indicated needle-like crystal formation—though different from ettringite; X and P admixtures showed sulfur peaks in Energy Dispersive Spectrum (EDS) spectra, like ettringite. SEM images and X-ray analyses of mixtures incorporating Portland Limestone Cement (PLC) indicated lower-than-average porosity but showed different Si/Ca and Al/Ca atomic ratios.

APA, Harvard, Vancouver, ISO, and other styles

12

Pazderka, Jiří. "Concrete with Crystalline Admixture for Ventilated Tunnel against Moisture." Key Engineering Materials 677 (January 2016): 108–13. http://dx.doi.org/10.4028/www.scientific.net/kem.677.108.

Full text

Abstract:

The paper deals with the use of concrete with crystalline admixture for special remedial structure which is exposed to intensive ground moisture and high level of air humidity. Additional protection of ground part of older buildings against subsurface water and ground moisture is one of the most important measures to ensure their long-time durability and satisfactory user properties. One of the most used remediation method are the air ducts which principle is to enable air flow along the moist structure surface to allow the sufficient evaporation of moisture from the structure. This group of methods includes also the ventilated underground tunnel along the perimeter walls. Presently the ventilated tunnels are designed as masonry structure whose durability in contact with the ground moisture is limited. The paper introduces a new technical solution of this method based on the special shaped concrete blocks whose durability is ensured by using of concrete with crystalline admixture. The waterproofing effect of the crystalline admixture is declared by the results of laboratory tests (in comparison with efficiency of crystalline coating).

APA, Harvard, Vancouver, ISO, and other styles

13

Dvorkin, Leonid, Nataliya Lushnikova, Oleksandr Bezusyak, Mohammed Sonebi, and Jamal Khatib. "Hydration characteristics and structure formation of cement pastes containing metakaolin." MATEC Web of Conferences 149 (2018): 01013. http://dx.doi.org/10.1051/matecconf/201814901013.

Full text

Abstract:

Metakaolin (MK) is one of the most effective mineral admixtures for cement-based composites. The deposits of kaolin clays are wide-spread in the world. Metakaolin is comparable to silica fume as an active mineral admixture for cement-based composites. In this paper, the rheological and mechanical properties of cement paste containing metakaolin are investigated. The effect of MK is more evident at “tight” hydration conditions within mixtures with low water-cement ratio, provided by application of superplasticizers. The cement is replaced with 0 to 15% metakaolin, and superplasticizer content ranged from 0 to 1.5% by weight of cementitious materials (i.e. cement and metakaolin). An equation is derived to describe the relationship between the metakaolin and superplasticizer content and consistency of pastes. There is a linear dependence between metakalolin content and water demand. Second-degree polynomial describe the influence of superplasticizer content. The application of SP and MK may produce cement-water suspensions with water-retaining capacity at 50-70% higher than control suspensions. The investigation of initial structure forming of cement pastes with SP-MK composite admixture indicates the extension of coagulation structure forming phase comparing to the pastes without additives. Crystallization stage was characterized by more intensive strengthening of the paste with SP-MK admixture comparing to the paste without admixtures and paste with SP. Results on the porosity parameters for hardened cement paste indicate a decrease in the average diameter of pores and refinement of pore structure in the presence of metakaolin. A finer pore structure associated with an increase in strength. X-ray analysis data reveal a growing number of small-crystalline low-alkaline calcium hydrosilicates and reducing portlandite content, when MK dosage increases. Scanning electron microscopy (SEM) data confirm, that hardened cement paste containing MK has crystalline structure with dominance of partially crystalized hydrosilicates and gel-like formations.

APA, Harvard, Vancouver, ISO, and other styles

14

Figala, Petr, Rostislav Drochytka, Vit Černý, and Pavel Dohnálek. "The Development of a New Chemically Resistant Sprayed Mixture." Solid State Phenomena 336 (August 30, 2022): 185–91. http://dx.doi.org/10.4028/p-248gp8.

Full text

Abstract:

This paper deals with research and development of a new chemically resistant sprayed mixture based on portland cement and special admixtures. The new material will be part of a comprehensive remediation system for the remediation of chemically attacked and stressed sewer structures. The aim of this work is to verify the effect of the amount of crystalline waterproofing admixture on selected physical-mechanical characteristics and chemical resistance, specifically resistance to the attack of sulphate solution and the attack of aggressive biogenic sulfuric acid solution. Furthermore, the resulting characteristics of test specimens manufactured in the laboratory and test specimens made by spraying into boxes and subsequent cutting to the required dimensions were compared. Due to the fact that there is currently no official methodology in the Czech Republic for testing the chemical resistance of cementitious materials intended for sewage environments, the methodology was used in accordance with DIN 19573 "Draft on mortars for construction and rehabilitation sewer systems". The sulphate resistance was determined for test specimens measuring 160×40×10mm, which were exposed to a solution of sulphate salts with a concentration of 29.8g / l (44g/l Na2SO4) for 91days. To determinate the resistance to biogenic sulfuric acid, special tanks were assembled in which the test specimens, measuring 80×40×40mm, were exposed for 14 days to a solution of sulfuric acid (H2SO4) with a molar concentration of 1,0mol/l (pH=0). The results of this work show the optimal amount of crystalline waterproofing admixture. The results of this work will be used in the next phase of research, when cement and some fillers will be substituted by selected secondary raw materials, namely to improve or at least maintain the key characteristics of the final sprayed mixture. Keywords: Sprayed mixture, Sulphates, Biogenic sulfuric acid, Chemical resistance, Crystalline waterproofing admixture

APA, Harvard, Vancouver, ISO, and other styles

15

Guzlena, S., and G. Sakale. "Self-healing concrete with crystalline admixture – a review." IOP Conference Series: Materials Science and Engineering 660 (December 4, 2019): 012057. http://dx.doi.org/10.1088/1757-899x/660/1/012057.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Ravitheja, A., T. Chandra Sekhara Reddy, and C. Sashidhar. "Self-Healing Concrete with Crystalline Admixture—A Review." Journal of Wuhan University of Technology-Mater. Sci. Ed. 34, no. 5 (October 2019): 1143–54. http://dx.doi.org/10.1007/s11595-019-2171-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Wang, Xiao Yan, Hong Jian Wang, Gui Qin Hou, and Zhao Xia Lv. "Preparation of Activated Alumina Admixture." Applied Mechanics and Materials 84-85 (August 2011): 489–93. http://dx.doi.org/10.4028/www.scientific.net/amm.84-85.489.

Full text

Abstract:

Through calcining bauxite, the preparation of active alumina (Al2O3) admixture was investigated. The effect of calcination temperature and time on the activity of alumina was studied. Calcination production species and crystalline state were determined by X-ray diffractometer, and the specific surface area referred as an important parameter was also determined. The results showed that the best calcination process of acquiring activated alumina admixture was 500°C1.0h. Alkali-aggregate reaction was inhibited effectively by the active alumina admixture.

APA, Harvard, Vancouver, ISO, and other styles

18

Nasim, Mohd, U. K. Dewangan, and Shirish V. Deo. "Autonomous healing in concrete by crystalline admixture: A review." Materials Today: Proceedings 32 (2020): 638–44. http://dx.doi.org/10.1016/j.matpr.2020.03.116.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Weng, Tsai-Lung, and An Cheng. "Influence of curing environment on concrete with crystalline admixture." Monatshefte für Chemie - Chemical Monthly 145, no. 1 (March 27, 2013): 195–200. http://dx.doi.org/10.1007/s00706-013-0965-z.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Mircea, Călin G. R., Tudor Panfil Toader, and Andreea Mircea. "Research upon self-sealing of fibre reinforced mortar with integral crystalline waterproofing admixtures." MATEC Web of Conferences 361 (2022): 05011. http://dx.doi.org/10.1051/matecconf/202236105011.

Full text

Abstract:

The paper presents results of an experimental research made upon the self-sealing of a fibre reinforced mortar with an integral crystalline waterproofing admixture in a dosage rate of 1-3 % of the cement mass. Samples were pre-loaded in three point bending up to 90 % of the ultimate capacity and conditioned in wet-dry cycles. Micro-cracks width was measured with a microscope after pre-loading, and up to 20 days. The results show that the 3 % admixture content presents the superior self-sealing performance both in the terms of the self-sealing degree and self-sealing rate. According to the results, lower contents of crystal-line admixture cannot predict a desirable self-sealing target, despite the fact that the self-sealing potential/ability is indisputable and may take longer periods.

APA, Harvard, Vancouver, ISO, and other styles

21

Wu, Hexiang, Xi Chen, Yao Liu, Shuangxin Li, and Hongfeng Li. "Effect of Crystalline Admixture and Superabsorbent Polymer on Self-Healing and Mechanical Properties of Mortar." Materials 15, no. 17 (September 1, 2022): 6040. http://dx.doi.org/10.3390/ma15176040.

Full text

Abstract:

In this study, the self-healing properties of mortars mixed with a crystalline admixture (CA) and superabsorbent polymer (SAP) were investigated. By conducting uniaxial compressive strength tests on the mortar samples, the effects of the two admixtures and different admixture ratios on the initial compressive strength and strength repair ability at different curing ages of the mortar after pre-cracking were investigated. To verify the results, optical microscopy, scanning electron microscopy, and X-ray diffraction were used for microscopic observation of the cracks and their healing products. The results of this study show that CA, which generates dense substances through chemical reactions, has obvious advantages in the self-healing of microcracks and has a greater effect on the flexural strength of mortar compared with SAP, which can effectively fill wider cracks, reduce the width of cracks through physical expansion, and has a greater impact on the compressive strength of mortar compared with CA. Compared with ordinary mortar, mortar mixed with CA only, and mortar mixed with SAP only, the appropriate amounts of both CA and SAP can effectively combine the advantageous effects of CA and SAP and optimise the self-healing effect of mortar so that its self-healing rate reaches 103%. The self-healing filler, consisting mainly of calcium silicate and calcium carbonate, is generated in cracks and enhances the repair strength of the mortar so that the strength of the mortar reaches 46 MPa.

APA, Harvard, Vancouver, ISO, and other styles

22

Ferrara, Liberato, Estefania Cuenca, Antonio Tejedor, and Enricomaria Gastaldo Brac. "Performance of concrete with and without crystalline admixtures under repeated cracking/healing cycles." MATEC Web of Conferences 199 (2018): 02016. http://dx.doi.org/10.1051/matecconf/201819902016.

Full text

Abstract:

The present paper analyses the repeatability of self-healing capacity in fibre reinforced concretes, both autogenous or enhanced by the addition of crystalline admixtures. The behaviour of the investigated concrete mixes was analysed by means of the “Double Edge Wedge Splitting (DEWS)” test, whose configuration and specimen geometry (150x15x50 mm) allow to predetermine the failure plane and the relative orientation of fibres. Initially, specimens were pre-cracked up to a crack width of 0.25 mm, then they were subjected for 1, 3 and 6 months to different exposure conditions, including water immersion, open air exposure and wet/dry cycles After that, specimens were subjected to repeated cracking and healing cycles, alternatively for 1 and 2 months, and up to an overall duration of one year. The crack closure index was evaluated using photogrammetric methods. The results highlighted the potentials of crystalline admixture in guaranteeing a better persistence of the healing performance in the long term and under repeated cracking and curing cycles.

APA, Harvard, Vancouver, ISO, and other styles

23

Kucha, H., and E. F. Stumpfl. "Thiosulphates as precursors of banded sphalerite and pyrite at Bleiberg, Austria." Mineralogical Magazine 56, no. 383 (June 1992): 165–72. http://dx.doi.org/10.1180/minmag.1992.056.383.03.

Full text

Abstract:

AbstractBanded sphalerite from Bleiberg, Austria, contains ubiquitous relics of Fe-thiosulphates and Fesulphites up to 50 μm in size. Zn, Pb, Ni and As form admixtures ranging from a few to 12 wt.% in these compounds. It is suggested that banded sphalerite is formed by a replacement of banded thiosulphate and thiosulphite precursors. This suggestion is supported by a significant admixture of Fe 0.41-8.20 wt.%) and the presence of goethite inclusions in banded sphalerite. In contrast, crystalline ZnS intergrown with the banded variety is Ni-free and contains only 0.06-0.14 wt.% Fe.Banded pyrite contains inclusions of Fe-thiosulphate up to 200 μm in size. These thiosulphates contain (wt.%): 0.09-1.92 Zn, and 2.67−4.02 Pb. Pyrite formed by replacement (breakdown) of Fethiosulphate precursors contains 3.69-3.83 wt.% Pb.It is suggested that banded sulphides precipitate from solutions carrying sulphur with mixed valances, and crystalline sulphides grow from solutions where the dominant dissolved sulphur is in the form of sulphidic anions.

APA, Harvard, Vancouver, ISO, and other styles

24

Hrbek, Vladimír, Veronika Petráňová, and Jiří Němeček. "Early Stage Microstructure Development of Cement Paste Modified by Crystalline Admixture." Key Engineering Materials 722 (December 2016): 92–99. http://dx.doi.org/10.4028/www.scientific.net/kem.722.92.

Full text

Abstract:

The hydrophobicity enhancement of structural materials is a contemporary topic of discussion. This paper deals with the effect of crystalline admixture (CA) on the microstructure of the cementitious composite in first four weeks after the production. Previous investigation was performed on the referential specimens consisting only from pure cement. The samples of pure CA and cement modified by 1% of CA with same w/c ratio were examined and compared in this paper. By investigation of these materials on the micro-scale in the time, it is possible to identify the development of the microstructure of each and determine the impact of the modification. For this purpose, backscattered electrons microscopy (BSE) with energy-dispersive X-ray spectroscopy (EDX) was used for phase analysis as well as instrumental nano-indentation to obtain the micro-mechanical properties. The presented results show the evolution of mechanical properties and microstructure in time and the impact of the crystalline admixture on modified cement.

APA, Harvard, Vancouver, ISO, and other styles

25

Yang, Yu-chuan, Hai-bo Li, Xing-guo Yang, Shi-quan Chen, and Jia-wen Zhou. "Experimental Study on the Influence of a Cementitious Permeable Crystallization Admixture (CPCA) in Improving Concrete Durability." Advances in Civil Engineering 2022 (May 29, 2022): 1–14. http://dx.doi.org/10.1155/2022/4305613.

Full text

Abstract:

The corrosion of steel reinforcement in reinforced concrete is a serious problem affecting the durability of concrete structures. And the steel corrosion caused by chloride ion erosion is the most serious damage to reinforced concrete structures, which affects the safety and service life of the structure. In order to prevent steel corrosion caused by chloride, it is necessary to pay more attention to chloride ion penetration damage. At present, the most commonly used method is to use additives in concrete structures, so as to improve the durability of concrete by reducing its permeability coefficient. Cement-based permeable crystalline admixtures can effectively improve the impermeability and mechanical properties of concrete by complex crystallization reactions between reactive chemicals and cement gels. In the paper, the Penetron admix 803 was selected as a typical CPCA in the experimental study, and the rapid chloride migration (RCM) experiments and mechanics experiments were carried out for four concrete structures with different dosages of Penetron admix 803 (PA8). Compared with plain concrete, the concrete structure containing PA8 makes it difficult for water and other liquids to enter by filling micropores and shrinkage cracks by scanning electron microscope test, so its impermeability is greatly improved. And concrete structure containing permeable crystalline admixture can reduce chloride ion permeability effectively. The experimental results showed that with the increase of PA8 content, the diffusion coefficient of the concrete structure decreased rapidly from 45.8 × 10−12 m2/s to 17.7 × 10−12 m2/s, while the service life of concrete structures increased continuously. And the mechanism of the chemical reaction between PA8 and the internal components of concrete structure was revealed, which was mainly due to the catalytic reaction between the reactive chemicals of PA8 and the cement hydrates of concrete structure forming insoluble crystals filled with concrete micropores. Experimental and theoretical results indicate that the permeable crystalline admixture can greatly improve the chloride-related durability and mechanical properties of the concrete structure.

APA, Harvard, Vancouver, ISO, and other styles

26

Manhanga, Fallon Clare, Žymantas Rudžionis, Ernestas Ivanauskas, and Algirdas Augonis. "The investigations on properties of self-healing concrete with crystalline admixture and recycled concrete waste." MATEC Web of Conferences 364 (2022): 05002. http://dx.doi.org/10.1051/matecconf/202236405002.

Full text

Abstract:

The concept of self-healing concrete is becoming more necessary as sustainability in construction is more desirable. Amongst the current solutions in this technology are autogenous, chemical, and bacterial self-healing. It is paramount that secondary raw materials be used in the production of selfhealing concrete as a form of a sustainable solution. Therefore, in this paper, the admixture “Betocrete-CP-360-WP”, which is a crystallizing waterproofing admixture with hydrophobic effect and is 100% recyclable, has been used and its effect on the physical, chemical, and mechanical properties of concrete, as well as selfhealing capabilities of concrete, have been determined. According to the obtained results, the crystalline additive “Betocrete-CP-360-WP” has no effect on density and slightly increases the amount of entrained air in the concrete mix. However, it does decrease the workability of the concrete mixture which could prove problematic in transportation to the construction site or in concreting in general. Also, with the crystalline admixture in the concrete mix, a 60% reduction in concrete compressive strength after one day of hardening has been estimated, but after 7 and 28 days, the strength attained is within the ranges of the control samples. In addition, concrete containing Betocrete-CP360-WP was 30% less water permeable as compared to control samples. The self-healing efficiency of the concrete was determined by a water flow test through a formed crack (approximately 0.35 mm wide). This was done by gluing a plastic pipe to the top of the cracked concrete specimens and maintaining a constant pressure of the water in the pipe. The experiment was continued for 28 days, and the crack self-healing efficiency of the concrete was calculated from the differences in the amount of water passed through the crack before healing and after 7, 14, 21 and 28 days of the healing process. After 28 days of the water flow test, the cracks in the concrete with the crystalline admixture and recycled concrete dust were completely healed, while the control specimens were not.

APA, Harvard, Vancouver, ISO, and other styles

27

Geraldo, R. H., A. M. Guadagnini, and G. Camarini. "Self-healing concrete with crystalline admixture made with different cement content." Cerâmica 67, no. 383 (September 2021): 370–77. http://dx.doi.org/10.1590/0366-69132021673833118.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

de Souza Oliveira, Aline, Jo Dweck, Eduardo de Moraes Rego Fairbairn, Otávio da Fonseca Martins Gomes, and Romildo Dias Toledo Filho. "Crystalline admixture effects on crystal formation phenomena during cement pastes’ hydration." Journal of Thermal Analysis and Calorimetry 139, no. 6 (September 3, 2019): 3361–75. http://dx.doi.org/10.1007/s10973-019-08745-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Wolarz, E., Th Fischer, and J. Stumpe. "Photoreorientation in Liquid Crystalline Side-Group Polysiloxane with Azobenzene Derivative Admixture." Molecular Crystals and Liquid Crystals 437, no. 1 (June 1, 2005): 1/[1245]—9/[1253]. http://dx.doi.org/10.1080/15421400590955758.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Pavlů, Tereza, Kristina Fořtová, Jakub Řepka, Diana Mariaková, and Jiří Pazderka. "Improvement of the Durability of Recycled Masonry Aggregate Concrete." Materials 13, no. 23 (December 1, 2020): 5486. http://dx.doi.org/10.3390/ma13235486.

Full text

Abstract:

The use of recycled masonry aggregate for concrete is mostly limited by the worse properties in comparison with natural aggregate. For these reasons it is necessary to find ways to improve the quality of recycled masonry aggregate concrete and make it more durable. One possibility is utilization of crystalline admixture which was verified in this study by laboratory measurements of key material properties and durability. The positive influence of mineral admixture was proved for freeze-thaw resistance. The positive impact to carbonation resistance was not unambiguous. In conclusion, the laboratory evaluation shows how to improve the durability of recycled masonry aggregate concrete, however, it is necessary to investigate more about this topic.

APA, Harvard, Vancouver, ISO, and other styles

31

Al-Kheetan, Mazen J., Mujib M. Rahman, and Denis A. Chamberlain. "Development of hydrophobic concrete by adding dual-crystalline admixture at mixing stage." Structural Concrete 19, no. 5 (March 23, 2018): 1504–11. http://dx.doi.org/10.1002/suco.201700254.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Lalik, Sebastian, Olaf Stefańczyk, Dorota Dardas, Natalia Górska, Shin-ichi Ohkoshi, and Monika Marzec. "Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)." Materials 14, no. 16 (August 21, 2021): 4722. http://dx.doi.org/10.3390/ma14164722.

Full text

Abstract:

The aim of this paper is to show, by systematic studies, the influence of γ-Fe2O3 nanoparticles on the physical parameters of the liquid crystalline matrix, exhibiting a ferroelectric phase in a wide temperature range. The detailed research was carried out by using diffraction (PXRD), microscopic (OM, SEM, FCPM, POM), thermal (DSC), optical (TLI), electric and spectroscopic (FTIR) methods. We show that even the smallest concentration of γ-Fe2O3 nanoparticles largely modifies the parameters of the ferroelectric SmC* phase, such as spontaneous polarization, switching time, tilt angle, rotational viscosity, dispersion anchoring energy coefficient and helix pitch. The admixture also causes a significant reduction in the temperature of phase transitions, broadening the SmA* phase at the expense of the SmC* phase and strong streaking of the texture. We present and explain the non-monotonic modification of these parameters with an increase in the nanoparticle concentration. The influence of oleic acid admixture on these parameters is also widely discussed. We have shown that certain parameters of organic-metal nanocomposites can be controlled by the appropriate amount of metal admixture.

APA, Harvard, Vancouver, ISO, and other styles

33

Gupta, R., and A. Biparva. "Do crystalline water proofing admixtures affect restrained plastic shrinkage behavior of concrete?" Revista ALCONPAT 7, no. 1 (January 31, 2017): 15–24. http://dx.doi.org/10.21041/ra.v7i1.172.

Full text

Abstract:

Do crystalline water proofing admixtures affect restrained plastic shrinkage behavior of concrete?ABSTRACTThis paper describes the effect of crystalline water proofing admixtures on early-age cracking in concrete. The performance of three different types of these admixtures was compared to that of control. This study has been performed in two stages. Stage one was performed under ASTM specified conditions and a modified stage where more severe drying conditions than that described in the ASTM test standard were used. These modified conditions simulated inadequate curing under extreme exposure conditions as experienced by concrete in many parts of the world. The test results indicate that the water proofing admixtures can effectively reduce the early-age shrinkage cracking. The possible reasons for this secondary advantage of crystalline water proofing admixture is also hypothesized in this paper.Keywords: restrained plastic shrinkage cracking; crystalline water proofing admixtures; crack reduction ratio; time to first crack.¿Los aditivos de impermeabilización cristalina afectan al comportamiento de retracción plástica restringida del concreto?RESUMENEste artículo describe el efecto de las mezclas cristalinas de impermeabilización sobre el agrietamiento en concreto a temprana edad. El rendimiento de tres tipos diferentes de estos aditivos se comparó con el de control. Este estudio se ha realizado en dos etapas: la primera se realizó bajo condiciones especificadas por ASTM y la segunda fue una modificación de la primera, en la que se usaron condiciones de secado más severas que las descritas en la norma de ensayo ASTM. Estas condiciones modificadas simulaban un curado inadecuado en condiciones extremas de exposición como las experimentadas por el concreto en muchas partes del mundo. Los resultados de la prueba indican que los aditivos de impermeabilización cristalina pueden reducir eficazmente el agrietamiento por retracción a edad temprana. Las posibles razones de esta ventaja secundaria son también supuestas en este trabajo.Palabras clave: agrietamiento por retracción plástica restringida; mezclas cristalinas de impermeabilización; relación de reducción de grietas; tiempo para la primera grieta.Faça aditivos impermeabilizantes cristalinas afetar o comportamento de retração plástica concreta restrito?RESUMOEste artigo descreve o efeito da mistura cristalina impermeabilização na fissuração do concreto em uma idade precoce. O desempenho de três tipos diferentes destes aditivos foi comparado com o controlo. Este estudo foi conduzido em duas fases: a primeira foi realizada em condições especificadas pela norma ASTM e o segundo foi uma modificação do primeiro, no qual foram usadas condições mais severas do que as descritas para o ensaio ASTM seca. Estas condições modificadas simulando cura inadequada em condições de exposição extrema vivida por concreto em muitas partes do mundo. Os resultados dos testes indicam que o aditivo impermeabilizante cristalino pode efetivamente reduzir o encolhimento rachaduras cedo. As possíveis razões para esta vantagem secundário também é assumida neste trabalho.Palavras-chave: retração plásticas rachaduras restritas; impermeabilização de misturas cristalinas; taxa de redução rachaduras; tempo para a primeira rachadura.

APA, Harvard, Vancouver, ISO, and other styles

34

Chandra Sekhara Reddy, T., and A. Ravitheja. "Macro mechanical properties of self healing concrete with crystalline admixture under different environments." Ain Shams Engineering Journal 10, no. 1 (March 2019): 23–32. http://dx.doi.org/10.1016/j.asej.2018.01.005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Krelani, Visar, and Liberato Ferrara. "Reducing the Porosity and Sealing Cracks by Using Crystalline Admixture in Conventional Concrete." International Journal of Business & Technology 6, no. 3 (May 1, 2018): 1–11. http://dx.doi.org/10.33107/ijbte.2018.6.3.17.

Full text

Abstract:

There is a continuous increase of quality on civil engineering materials in developed countries and parallel increase of need for new constructions in developing countries. Professional community should propose solutions for the durability that can resist in different severe environments. The most important factor that can affect concrete durability is represented by the pore distribution. Transport properties can take place through the porous network inside the cementitious composites and the aggregates interface, permitting the ingress of aggressive agents damaging concrete function intrinsically as a material and the wellfunctioning of the entire structure. The use of a crystalline admixture during the mixing procedure can fill the pores and capillarity of the cement composites, while in case of the appearance of the cracks, can perform as sealing agent, representing a secondary innovative benefit. Concrete structure, in this case will be more durable and there will be no need for unplanned intervention.

APA, Harvard, Vancouver, ISO, and other styles

36

Hermawan, Harry, Guadalupe Sierra Beltran, Virginie Wiktor, Pedro Serna, and Elke Gruyaert. "Effect of healing agents on the rheological properties of cement paste and compatibility with superplasticizer." MATEC Web of Conferences 361 (2022): 05008. http://dx.doi.org/10.1051/matecconf/202236105008.

Full text

Abstract:

Self-healing concrete is considered as a new generation of concrete with the ability to heal cracks without human intervention. The healing agents are incorporated into the concrete to activate the healing mechanism and to improve the healing efficiency. While both lab- and large-scale projects have shown that the addition of healing agents can have a possible positive effect on the hardened concrete properties (e.g. compressive strength), unfortunately, the evaluation of fresh properties of self-healing concrete mixes is often neglected. In the current study, the effect of healing agents is clearly identified starting from the paste level. Different techniques were used to study the effect of healing agents on the consistency, viscosity and adsorption behaviour of PCE-based superplasticizer in cement paste. A crystalline admixture and bacteria were used as healing agents, and CEM III/A was used as the binder component of the paste. The results showed that the inclusion of bacteria did not influence the rheological properties of the cement paste and no incompatibility issues were found with the superplasticizer. On the other hand, the presence of the crystalline admixture in the paste interfered with the rheological properties of the cement paste as a reduction of workability, an increase of paste viscosity, and an increased adsorption of superplasticizer.

APA, Harvard, Vancouver, ISO, and other styles

37

Uygunoğlu, Tayfun, and İlker Bekir Topçu. "Effect of Water Proofing Materials on Self-Healing Concrete." European Journal of Formal Sciences and Engineering 3, no. 1 (May 15, 2020): 35. http://dx.doi.org/10.26417/190vto47v.

Full text

Abstract:

Improving the strength of the concrete structures and increasing the service life is an important issue. The service times of the concrete remained; external factors such as water penetrating into these micro-cracks and shorten the life of the concrete. In order to solve this problem, the idea of self-healing concrete with bacteria or other materials has been put forward and studies have shown that using CaO based materials that repair cracks in this direction by precipitating calcite. It is obvious that long term performance of concrete will increase with to prevent water pass to concrete interior. Instead of forming a barrier on the positive or negative side of concrete, water proofing admixture turn the concrete itself into a water barrier. Internal concrete waterproofing systems can be water repellents or crystalline admixtures. In this study, water proofing admixture was added to concrete mixture as water proofing material and its effect on self-healing in terms of filling the pores was investigated. Beam samples including the CaO based water proofing powder materials were produced in size of 285x75x25 mm. The samples were cracked in the flexural machine. After some days, the cracks were investigated by microscope. Crak control was continued till 28 days. At the end of study, the cracks smaller than 0.3 mm were self-healed. However, the bigger cracks than 0.3 mm cannot be self-healed by water proofing material. Consequently, self-healing of concrete with CaO based water proofing powder material is very promising for the environmentally friendly and sustainable structures of the future.

APA, Harvard, Vancouver, ISO, and other styles

38

Cuenca, Estefanía, Stefano Rigamonti, Enricomaria Gastaldo Brac, and Liberato Ferrara. "Crystalline Admixture as Healing Promoter in Concrete Exposed to Chloride-Rich Environments: Experimental Study." Journal of Materials in Civil Engineering 33, no. 3 (March 2021): 04020491. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0003604.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Buller, Abdul Salam, Fahad ul Rehman Abro, Kwang-Myong Lee, and Seung Yup Jang. "Mechanical Recovery of Cracked Fiber-Reinforced Mortar Incorporating Crystalline Admixture, Expansive Agent, and Geomaterial." Advances in Materials Science and Engineering 2019 (September 22, 2019): 1–14. http://dx.doi.org/10.1155/2019/3420349.

Full text

Abstract:

This research is sought to characterize the stimulated autogenous healing of fiber-reinforced mortars that incorporate healing agents such as crystalline admixtures, expansive agents, and geomaterials. The effects of the healing materials on mechanical performance and water permeability were evaluated experimentally. Furthermore, microscopic and microstructural observations were conducted to investigate the characteristics and physical appearance of healing products within healed cracks. Test results are presented herein regarding index of strength recovery (ISR), index of damage recovery (IDR) and index of dissipation energy gain (IDEG) in relation to crack healing, and reduction of water flow rate. The self-healing capability of the mortars was greater in terms of resisting water flow rather than recovering mechanical performance likely because water flow depends on surface crack sealing, whereas mechanical performance depends on bonding capacity as well as full-depth healing of cracks; thus, mechanical performance may further be improved after longer healing duration.

APA, Harvard, Vancouver, ISO, and other styles

40

Hull, A. W. "A New Method Of X-Ray Crystal Analysis." Powder Diffraction 7, no. 1 (March 1992): 13–27. http://dx.doi.org/10.1017/s0885715600016018.

Full text

Abstract:

The beautiful methods of crystal analysis that have been developed by Laue and the Braggs are applicable only to individual crystals of appreciable size, reasonably free from twinning and distortion, and sufficiently developed to allow the determination of the direction of their axes. For the majority of substances, especially the elementary ones, such crystals cannot be found in nature or in ordinary technical products, and their growth is difficult and time-consuming.The method described below is a modification of the Bragg method, and is applicable to all crystalline substances. The quantity of material required is preferably 0.005 c.c., but one tenth of this amount is sufficient. Extreme purity of material is not required, and a large admixture of (uncombined) foreign material, twenty or even fifty per cent, is allowable provided it is amorphous or of known crystalline structure.

APA, Harvard, Vancouver, ISO, and other styles

41

Nasim, Mohd, U. K. Dewangan, and Shirish V. Deo. "Effect of crystalline admixture, fly ash, and PVA fiber on self-healing capacity of concrete." Materials Today: Proceedings 32 (2020): 844–49. http://dx.doi.org/10.1016/j.matpr.2020.04.062.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Reddy, T. Chandra Sekhara Reddy, A. Ravitheja Theja, and C. Sashidhar. "Self-Healing Ability of High-Strength Fibre-Reinforced Concrete with Fly Ash and Crystalline Admixture." Civil Engineering Journal 4, no. 5 (June 3, 2018): 971. http://dx.doi.org/10.28991/cej-0309149.

Full text

Abstract:

The aim of this study is to analyse the self-healing capability of high-strength fibre-reinforced concrete (M70) with fly ash and crystalline admixture (CA) in four types of environmental exposures i.e. Water Immersion (WI), Wet-Dry Cycles (WD), Water contact (WC) and Air Exposure (AE). Specimens for four mixes are cast, one mix containing 1.1% of CA and three mixes with 10%, 20% and 30% partial replacement of cement with fly ash and additions of 1.1% CA. The specimens were pre-cracked at 28 days, in the range of 0.10-0.40 mm and the time set for healing was 42 days. The result shows that all the mixes have considerable amount of closing ability and strength-regaining capability for all exposure conditions. The concrete with 20% fly ash and 1.1% CA has complete crack closing ability and 100% strength-regaining capability for WI and WD cycle conditions. From SEM analysis, it is confirmed that self-healing products are CaCO3 and C-S-H gel.

APA, Harvard, Vancouver, ISO, and other styles

43

Li, Desheng, Bing Chen, Xihui Chen, Bing Fu, Hongchao Wei, and Xiaorui Xiang. "Synergetic effect of superabsorbent polymer (SAP) and crystalline admixture (CA) on mortar macro-crack healing." Construction and Building Materials 247 (June 2020): 118521. http://dx.doi.org/10.1016/j.conbuildmat.2020.118521.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Jamroz, Dorota, Agnieszka Gajda-Janiak, Zbigniew Wzorek, Zygmunt Kowalski, and Janusz Kubizna. "Chemical and Biological Characteristics of Different Hydrated Monocalcium Phosphates for Broiler Chickens." Annals of Animal Science 12, no. 2 (March 1, 2012): 187–200. http://dx.doi.org/10.2478/v10220-012-0016-4.

Full text

Abstract:

Chemical and Biological Characteristics of Different Hydrated Monocalcium Phosphates for Broiler ChickensThree hydrated monocalcium phosphates differing in purity (with or without monetite, or monetite and calcite) and in crystalline structure were used in broiler chickens diets. The performance indices, concentration of Ca, P and Mg and activity of alkaline phosphatase in blood plasma, the content of these mineral elements in bones, and physico-mechanical parameters of femur and tibia bones were recorded. Body weight on 35th day of life, feed intake and mechanical parameters of bone quality were slightly affected by the type of phosphates used. Higher Ca and P concentration in blood was stated in chickens fed diets with greater purity of phosphates, but activity of alkaline phosphatase has increased with the admixture of monetite or calcite used in phosphates. The best parameters of bone quality were found in the treatment in which hydrated monocalcium phosphate (MCP) with admixture of monetite and calcite was applied. Higher concentration of both Ca and Mg in bone was determined in chickens fed diets with pure phosphates.

APA, Harvard, Vancouver, ISO, and other styles

45

Li, Changming, Xiaoxiong Chai, Hui Liu, Haifeng Cheng, Dongyang Jia, Longfei Di, Songlin Qin, and Yongbao Jin. "Research on the Mechanical Properties and Microstructure of Modified Silt Sediment Geopolymer Materials." Gels 8, no. 12 (December 2, 2022): 792. http://dx.doi.org/10.3390/gels8120792.

Full text

Abstract:

The treatment of silted sediment in the river is a global problem. The accumulation of waste sediment will lead to an adverse impact on the environment. In this paper, the silted sediment was reused to produce geopolymer composite materials via alkali-activated gelling modification. The effects of the modifiers of sodium silicate solution, quicklime, and Na2SO4 admixture, and the dosage of the slag, fly ash, and silica fume admixture, and curing conditions and age, on the compressive strength and microstructure of the geopolymer-modified sediment materials were studied. The crystalline phase and hydration products of the modified sediment geopolymer composites were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), respectively. A compressive strength test was conducted to evaluate the mechanical properties of the composites. The results showed that the type and dosage of modifier, amount of mineral admixture additive, cure conditions, and cure age had significant effects on the mechanical properties of the composites. The effect of the addition of mineral admixture on the compressive strength of the modified sediment specimens was more noticeable than that of the modifier. The compressive strength of the geopolymer-modified specimens was greatly increased by the addition of mineral dopants. When 10 wt.% silica fume is added, the compressive strength reaches a maximum value of 33.25 MPa at 60 days. The SEM-EDS results show that the C-S-H gels and C-A-S-H gels were the main hydration products. The results indicate that river siltation sediment is an excellent raw material for geopolymer-modified materials. It is feasible to produce reliable and sustainable hydraulic engineering materials by using river sediment geopolymer-modified materials.

APA, Harvard, Vancouver, ISO, and other styles

46

Melichar, Jindřich, Vit Černý, and Rostislav Drochytka. "The Influence of the Waste Foundry Sand on the Microstructure and the Physico-Mechanical Properties of Autoclaved Aerated Concrete." Materials Science Forum 998 (June 2020): 293–98. http://dx.doi.org/10.4028/www.scientific.net/msf.998.293.

Full text

Abstract:

Thanks to its porous structure the autoclaved aerated concrete has excellent thermal insulation properties. The production of this building material is carried out in two main steps. At first calcium hydroxide reacts with aluminum powder. This reaction releases hydrogen which creates the porous structure. Secondly lime reacts with siliceous components under hydrothermal conditions. This reaction forms crystalline calcium hydrosilicates which represent a binder component in the material. Focus of this paper is to study the degree of crystallization of calcium hydrosilicates depending on the quantity and fineness of the admixture of the waste foundry sand. This material was tested in three different values of specific surface. The influence of granularity of the waste foundry sand on the microstructure and physical-mechanical properties of the autoclaved aerated concrete was monitored. At the same time, the influence primary filler substitution by foundry sand was also observed. The substitution was realized in amounts of 10%, 30% and 50%. As the final step the influence of the waste foundry sand admixture on the autoclaved aerated concrete porous structure was evaluated. The microstructure was analyzed by X-ray diffraction. Obtained values show that admixture of waste foundry sand has positive effect on the crystallisation of calcium hydosilicate phases. Substitution of primary filler by waste foundry sand is possible up to 50%. With a higher amount of substitution, the higher values of compressive strength of autoclaved aerated concrete were monitored.

APA, Harvard, Vancouver, ISO, and other styles

47

Lo Monte, Francesco, and Liberato Ferrara. "Self-healing characterization of UHPFRCC with crystalline admixture: Experimental assessment via multi-test/multi-parameter approach." Construction and Building Materials 283 (May 2021): 122579. http://dx.doi.org/10.1016/j.conbuildmat.2021.122579.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Takagi, Emilio M., Maryangela G. Lima, Paulo Helene, and Ronaldo A. Medeiros Junior. "Self-healing of self-compacting concretes made with blast furnace slag cements activated by crystalline admixture." International Journal of Materials and Product Technology 56, no. 1/2 (2018): 169. http://dx.doi.org/10.1504/ijmpt.2018.089116.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Medeiros Junior, Ronaldo A., Maryangela G. Lima, Paulo Helene, and Emilio M. Takagi. "Self-healing of self-compacting concretes made with blast furnace slag cements activated by crystalline admixture." International Journal of Materials and Product Technology 56, no. 1/2 (2018): 169. http://dx.doi.org/10.1504/ijmpt.2018.10009994.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Xue, Caihong, Wengui Li, Fulin Qu, Zhihui Sun, and Surendra P. Shah. "Self-healing efficiency and crack closure of smart cementitious composite with crystalline admixture and structural polyurethane." Construction and Building Materials 260 (November 2020): 119955. http://dx.doi.org/10.1016/j.conbuildmat.2020.119955.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Crystalline admixture'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles