scholarly journals Property Analysis of Slag Composite Concrete Using a Kinetic–Thermodynamic Hydration Model

2021 ◽  
Vol 11 (16) ◽  
pp. 7191
Author(s):  
Ki-Bong Park ◽  
Yi-Sheng Wang ◽  
Xiao-Yong Wang
Keyword(s):  
Experimental Study ◽  
Thermodynamic Model ◽  
Experimental Studies ◽  
Hydration Heat ◽  
Strength Development ◽  
Phase Assemblage ◽  
Property Development ◽  
Hydration Model ◽  
Compressive Strength Development ◽  
Reaction Degree

Slag is increasingly unitized for the production of sustainable concrete. This paper presents a procedure with which to analyze the property development of slag composite concrete. Experimental studies of the hydration heat and compressive strength development and simulation studies using a kinetic hydration model and a thermodynamic model were performed. First, we performed an experimental study of the isothermal hydration heat of cement–slag blends. Based on the results of the experimental study on cumulative hydration heat, the reaction degree of slag was determined. We found that the reaction degree of slag decreased as the slag content increased. Second, the reaction degree of slag and cement were used as the input parameters for the Gibbs energy minimization (GEM) thermodynamic equilibrium model. Moreover, the phase assemblage of hydrating cement–slag was determined. The trends of calcium silicate hydrate (CSH) are similar to those of strength. Based on the CSH content, the strength of hardening cement–slag blends was determined. In addition, the calcium hydroxide (CH) content resulting from the thermodynamic model shows good agreement with the experimental results. In summary, the integrated kinetic–thermodynamic model is useful for analyzing the properties of cement–slag blends.

scholarly journals Analysis of Hydration and Optimal Strength Combinations of Cement-Limestone-Metakaolin Ternary Composite

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Xiao-Yong Wang
Keyword(s):  
Synergetic Effect ◽  
Dilution Effect ◽  
Pozzolanic Reaction ◽  
Parameter Analysis ◽  
Chemical Effect ◽  
Strength Development ◽  
Ternary Blends ◽  
Property Development ◽  
Hydration Model ◽  
Space Ratio

Metakaolin (MK) is an aluminosilicate pozzolan material and can contribute to property development of concrete due to the pozzolanic reaction. Limestone (LS) powder presents the dilution effect, nucleation effect, and chemical effect on hydration of cement. When metakaolin and limestone are used together, due to the additional chemical reaction between the aluminum phase in MK and limestone, the synergetic benefit can be achieved. This study presents a hydration model for cement-limestone-metakaolin ternary blends. Individual reactions of cement, metakaolin, and limestone are simulated separately, and the interactions among cement hydration, limestone reaction, and metakaolin reaction are considered through the contents of calcium hydroxide and capillary water. The hydration model considers the pozzolanic reaction of metakaolin, chemical and physics effects of limestone, and synergetic effect between metakaolin and limestone. Furthermore, the gel-space ratio of hydrating concrete is calculated using reaction degrees of binders and concrete mixtures. The strength development of ternary blends is evaluated using the gel-space ratio. Based on parameter analysis, the synergetic effect on strength development is shown and the optimal combinations of cement-limestone-metakaolin ternary blends are determined.

scholarly journals Clays as SCM – Reactivity of Uncalcined Kaolinite and Bentonite, and Impact on Phase Assemblage and Strength Development of PC Mortars

2019 ◽  
Vol 60 (1) ◽  
pp. 13-30
Author(s):  
Mette Rica Geiker ◽  
Emmanuel Gallucci
Keyword(s):  
Cement Paste ◽  
Chemical Reactivity ◽  
Engineering Properties ◽  
Strength Development ◽  
Phase Assemblage ◽  
Clay Particles ◽  
Compressive Strength Development ◽  
The Impact ◽  
Detrimental Impact ◽  
Porosity Measurements

Abstract The impact of substitution of cement paste with uncalcined clay (bentonite and kaolinite) in the range of 5% by volume of paste on the development of hydration and properties of mortar was investigated. Two issues were addressed, the expected filler effect of the dispersed sub-micron clay particles, and the possible chemical reactivity of the clay. The study indicated that Portland cement paste may be modified by addition of well dispersed clay and that the impact includes accelerated cement hydration as well as altered distribution of products. Compressive strength development was accelerated, but later age strength was reduced, especially for the bentonite mixes. In contrast, microscopic porosity measurements indicated no detrimental impact on the coarse capillary porosity. The investigation indicates that for durability related engineering properties, the application of uncalcined clay might be a potential means for reduction of the clinker factor in concrete in support of sustainability.

scholarly journals A Microstructure Based Strength Model for Slag Blended Concrete with Various Curing Temperatures

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Li-Na Zhang ◽  
Wang Xiao-Yong ◽  
Kyung-Taek Koh
Keyword(s):  
Numerical Model ◽  
Carbon Dioxide Emissions ◽  
Cement Hydration ◽  
Elevated Temperatures ◽  
Strength Development ◽  
Granulated Blast Furnace Slag ◽  
Proposed Model ◽  
Hydration Model ◽  
Compressive Strength Development ◽  
Reduce Carbon Dioxide

Ground granulated blast furnace slag, which is a byproduct obtained during steel manufacture, has been widely used for concrete structures in order to reduce carbon dioxide emissions and improve durability. This paper presents a numerical model to evaluate compressive strength development of slag blended concrete at isothermal curing temperatures and time varying curing temperatures. First, the numerical model starts with a cement-slag blended hydration model which simulates both cement hydration and slag reaction. The accelerations of cement hydration and slag reaction at elevated temperatures are modeled by Arrhenius law. Second, the gel-space ratios of hardening concrete are calculated using reaction degrees of cement and slag. Using a modified Powers’ gel-space ratio strength theory, the strength of slag blended concrete is evaluated considering both strengthening factors and weakening factors involved in strength development process. The proposed model is verified using experimental results of strength development of slag blended concrete with different slag contents and different curing temperatures.

scholarly journals The potential use of pumice in mine backfill

2020 ◽  
Vol 1 ◽  
Author(s):  
Mohammed A. Hefni
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Mining Industry ◽  
Strength Development ◽  
Natural Pozzolan ◽  
Mine Backfill ◽  
Natural Pozzolans ◽  
Cemented Backfill ◽  
Compressive Strength Development ◽  
Potential Use

Abstract The use of natural pozzolans in concrete applications is gaining more attention because of the associated environmental, economic, and technical benefits. In this study, reference cemented mine backfill samples were prepared using Portland cement, and experimental samples were prepared by partially replacing Portland cement with 10 or 20 wt.% fly ash as a byproduct (artificial) pozzolan or pumice as a natural pozzolan. Samples were cured for 7, 14, and 28 days to investigate uniaxial compressive strength development. Backfill samples containing 10 wt.% pumice had almost a similar compressive strength as reference samples. There is strong potential for pumice to be used in cemented backfill to minimize costs, improve backfill properties, and promote the sustainability of the mining industry.

scholarly journals The Hydration, Mechanical, Autogenous Shrinkage, Durability, and Sustainability Properties of Cement–Limestone–Slag Ternary Composites

2021 ◽  
Vol 13 (4) ◽  
pp. 1881
Author(s):  
Mei-Yu Xuan ◽  
Yi Han ◽  
Xiao-Yong Wang
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Experimental Studies ◽  
Autogenous Shrinkage ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Hydration Heat ◽  
Granulated Blast Furnace Slag ◽  
Binder Ratio

This study examines the hydration–mechanical–autogenous shrinkage–durability–sustainability properties of ternary composites with limestone filler (LF) and ground-granulated blast furnace slag (BFS). Four mixtures were prepared with a water/binder ratio of 0.3 and different replacement ratios varying from 0 to 45%. Multiple experimental studies were performed at various ages. The experimental results are summarized as follows: (1) As the replacement levels increased, compressive strength and autogenous shrinkage (AS) decreased, and this relationship was linear. (2) As the replacement levels increased, cumulative hydration heat decreased. At the age of 3 and 7 days, there was a linear relationship between compressive strength and cumulative hydration heat. (3) Out of all mixtures, the ultrasonic pulse velocity (UPV) and electrical resistivity exhibited a rapid increase in the early stages and tended to slow down in the latter stages. There was a crossover of UPV among various specimens. In the later stages, the electrical resistivity of ternary composite specimens was higher than plain specimens. (4) X-ray diffraction (XRD) results showed that LF and BFS have a synergistic effect. (5) With increasing replacement ratios, the CO2 emissions per unit strength reduced, indicating the sustainability of ternary composites.

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