Blast Furnace Slag Replacement Research Articles

Innovating with potassium-modified ceramic powder geopolymer mortar and the integration of recycled aggregates

This study develops an environmentally friendly geopolymer mortar (GM) that incorporates ceramic powder (CP) and recycled aggregate (RA), optimized through the use of potassium hydroxide (KH) and potassium silicate (KS) as alkaline activators under varied molarities and curing conditions. The research methodically evaluates the replacement of ground granulated blast furnace slag (GBFS) with CP at different ratios (25 %, 50 %, 75 %, and 100 %). Subsequently, RA is replaced with marble powder (MP) and glass powder (GP) in proportions of 25 %, 50 %, and 75 %. Physical and mechanical properties, including unit weight, water absorption, ultrasonic pulse velocity (UPV), compressive strength and flexural strength, are evaluated at various curing times. Furthermore, exposure to elevated temperatures and freezing-thawing cycles test the material's durability. Specifically, a peak improvement of 45.4 % in compressive strength is observed with 50 % GP replacement of 100 % RA, while high temperature resistance tests show increases of 28.57 % in compressive strength and 26.75 % in flexural strength at 800 °C. The incorporation of GP also has a minimal impact on freezing-thawing resistance, with a slight reduction of 5.84 % in compressive strength and 5.78 % in flexural strength. Advanced microstructural analysis using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared (FT-IR) spectroscopy reveals intricate details, confirming the significant efficacy of GP in improving GM properties. Furthermore, the analysis establishes a 94 % correlation between UPV and compressive strength and demonstrates the effectiveness of the material composition and processing conditions tailored to this study.

Modelling and optimization of multiple replacement of supplementary cementitious materials for cement composite by response surface method

Supplementary cementitious materials are beneficial in improving performance and lessening the cement consumption with highly lessening CO2 emission. Many researchers used blast furnace slag, bentonite, and active limestone separately or two of them together to improve the performance of cementing materials, however, it is not well known how all react together in cement composite materials. So, the present study used modeling and optimizing the replacement of blast furnace slag, raw bentonite, and active limestone each by the doses of 0 to 20% to maximize strength and minimize the fresh bulk density of cementing materials by central composite design-response surface method (CCD-RSM). The results found, the employment of blast furnace slag, bentonite, and active limestone in the cement composite materials generally lessens the early strength compared to the control mixture. However, the replacement of blast furnace slag and active limestone by 20% significantly improves the 28-days compressive strength while employing raw bentonite by 20% reduced compressive strength by 6.45% compared to the control mixture. However, blending raw bentonite with active limestone by half improved the compressive strength. Besides these, the substitution of bentonite and active limestone reduces the fresh bulk density and flexural strength than the control mixture. Generally, the study optimized depending on the criteria of maximizing strength and minimizing fresh density and found the mix design replacement of blast furnace slag 1.01%, raw bentonite 5.30%, and active limestone 20% that improves 28 days compressive strength simultaneously reduces fresh bulk density in addition to replacing more than 54 different optimized design mix results.

Evaluating the physicochemical properties of pervious recycled aggregate concrete incorporating pozzolanic additives under acid rain attack

The utilization of recycled concrete aggregate (RCA) from construction and demolition wastes to produce pervious concrete show various environmental benefits in the construction of sponge city. However, its durability performance in an acid rain attack environment has received less attention. This study aims to understand the deterioration of mechanical properties and microstructure of pervious recycled aggregate concrete (PRAC) exposed to simulated acid rain attack and drying-wetting cycles. The effects of the ground granulated blast-furnace slag (GGBS) replacement ratios, the silica fume (SF) replacement ratios and the erosion times on the mass loss, compressive strength, relative dynamic elastic modulus, permeability coefficient and porosity of PRAC were evaluated. The results demonstrated that the acid rain attack caused obvious mass loss and compressive strength reduction for PRAC without pozzolanic additives, thus resulted in increase on the permeability coefficient and porosity. Moreover, the physicochemical properties of PRAC decreased strongly with the increase of acid rain exposure time. Nevertheless, the addition of 20%GGBF and 7%SF in PRAC showed better resistance to acid attack due to the synergistic effect. The microscopic characterization revealed that the added pozzolanic additives declined the content of calcium hydroxide of matrix in PRAC and thereby inhibited the formation of gypsum, which delayed the acid rain erosion process.

Mechanical properties and energy absorption performance of foamed geopolymer under quasi-static and dynamic compression

To assess the potential for substituting foam concrete with low-carbon foamed geopolymer (FG) in the field of structural protection, a series of quasi-static and dynamic compression tests were conducted. These tests aimed to examine the mechanical performance and energy absorption of FG while considering the factors of FG density, granulated blast furnace slag (GBFS) replacement rate, and water–solid ratio. Additionally, supplementary investigations involving XRD analysis, indentation tests, X-CT scanning, and 3D reconstruction techniques were conducted to explore the influence of GBFS replacement rate on the energy absorption of FG in terms of base material properties and internal pore structure. The results of the quasi-static compressive tests showed that increasing the FG density and reducing the water–solid ratio had a positive effect on energy absorption, however, it also resulted in a notable increase in peak strength. Increasing the GBFS replacement rate not only enhanced the load-bearing capacity but also increased the extent of spalling damage, thus FG with a moderate GBFS replacement rate of 20% demonstrated superior performance in terms of energy absorption and load transfer. Under dynamic compression, all specimens predominantly experienced vertical splitting failure. However, with increasing loading velocity, crushing failure emerged at the two ends of the specimens, particularly in the case of low-density specimens. As the loading velocity increased, the specimen exhibited a significant increase in peak strength, demonstrating a notable strain rate effect, however, the energy absorption of the specimen remained relatively stable without significant alterations. In addition, a simplified DIF was proposed to predict the peak strength of FG with varying densities and two distinct GBFS replacement rates under different strain rates. It provided some valuable insights into the potential application of FG in the field of structural protection.

Effect of low-calcium fly ash inclusion on long-term mechanical properties and durability of ground granulated blast furnace slag-based cement-free mortars

The present study focused on fabricating cement-free mortar based on ground granulated blast furnace slag incorporating low-calcium fly ash as precursors in an alkaline solution of sodium hydroxide and sodium silicate. The main purposes of the study were not only to find the optimum mixture proportions to confirm the fly ash role in contributing to the long-term mechanical properties and durability but also to expand the use of fly ash in cement-free binders based on ground granulated blast furnace slag. The ground granulated blast furnace slag was replaced with fly ash in the cement-free mortar at various levels of 30, 40, 50, 60, and 70% by mass. The cement-based sample as a control sample was prepared for comparison purposes. Results showed that the cement-free mortar samples with fly ash had the more superior long-term mechanical properties (i.e. flexural and compressive strengths and volumetric compaction via ultrasonic pulse velocity test) and durability (i.e. total charge passed via rapid chloride penetration test and sulfate resistance via length change of samples exposed to sulfate solution), lower water absorption and porosity, and denser microstructure than the control sample up to 120 days. The 40% replacement of ground granulated blast furnace slag by fly ash as an auxiliary source of alumina and silica was the optimum ratio in enhancing the long-term mechanical properties and durability of the cement-free mortar samples, which is in agreement with reducing the porosity and water absorption. The results of the environmental analysis indicate that using cement-free mortar samples has much lower environmental impacts. The cement-free mortar sample using 60% ground granulated blast furnace slag and 40% fly ash is found as an optimal mixture in terms of technical and environmental features.

The Effects of Partial Replacement of Ground Granulated Blast Furnace Slag by Ground Wood Ash on Alkali-Activated Binder Systems.

Cement production contributes significantly to carbon dioxide emissions. Alkali-activated materials offer an environmentally friendly alternative due to their comparable strength, durability and low-carbon emissions while utilizing wastes and industrial by-products. Wood ash is a waste material that shows promising results as a partial replacement for Portland cement and precursors in alkali-activated systems. The aim of this study was to examine the effect of ground wood ash on the mechanical properties of alkali-activated mortars. Wood ash was incorporated as a 0 wt%, 10 wt% and 20 wt% partial replacement for ground granulated blast furnace slag (GGBFS). The wood ashes were ground in a planetary ball mill for 10 and 20 min. Sodium silicate (Na2SiO3), sodium carbonate (Na2CO3), and sodium hydroxide (NaOH) were used as alkali activators. The results demonstrated that ground wood ash improved the mechanical properties of alkali-activated systems compared to untreated wood ash. However, the incorporation of wood ash increased the porosity of the binder matrix.

Carbonation of blast furnace slag concrete at different CO2 concentrations: Carbonation rate, phase assemblage, microstructure and thermodynamic modelling

The carbonation behavior of concrete with different blast furnace slag replacement ratios (0 %, 50 % and 70 %) at different CO2 concentrations (natural carbonation at 0.04 % and accelerated carbonation at 1 % and 2 %) was investigated in terms of carbonation rate, carbonation products assemblage and pore structure. The results show that the porosity of concrete decreases with the increase in CO2 concentration regardless of mix proportion. The lower porosity at a higher CO2 concentration can lead to an underestimation of the natural carbonation coefficient from accelerated carbonation tests. The carbonation degree of the C-S-H is one of the key factors that determine the carbonation behavior at different CO2 concentrations. A higher CO2 concentration enhances the consumption of the high-density C-S-H and therefore the carbonation of unreacted clinker. However, the C-S-H formed from GGBFS hydration is carbonated to a more advanced state (considerable silica gel is formed) under natural carbonation.

Evaluation of Thermal Conductivity of Sustainable Concrete Having Supplementary Cementitious Materials (SCMs) and Recycled Aggregate (RCA) Using Needle Probe Test

The evaluation of thermal properties is commonly conducted to characterize non-structural materials, such as lightweight concrete, that are used for thermal insulation. Such materials are designed for thermal resistivity applications. Due to the increased demand to adopt sustainable practices in the construction industry, municipalities in the United Arab Emirates (UAE) emphasize the use of sustainable materials in construction, such as green concrete. The cement in green concrete is partially replaced with supplementary cementitious materials (SCMs); these materials are by-product waste from other industries. The SCMs can contribute to sustainability by reducing the concrete carbon footprint. They can also help in extending concrete durability and service life. However, there is still a lack in the literature regarding the effects of these materials on the thermal properties of concrete. This paper investigates the thermal properties of sustainable concrete mixes incorporating various types of SCMs. The SCMs that are considered in this investigation are fly ash, ground granulated blast-furnace slag (GGBS), and microsilica. Another way to improve the sustainability of the concrete is to partially replace the natural aggregates with recycled aggregates. Thus, a group of the concrete mixes in this investigation were prepared by replacing 40% of natural aggregates with recycled aggregates to investigate the effects of recycled aggregate on the thermal properties of concrete. Further, the thermal properties of three lightweight concrete mixtures commonly used in construction were evaluated. All concrete mixtures were examined for thermal conductivity and resistivity in accordance with ASTM D5334. The results of this investigation showed that SCMs and recycled aggregates have a significant impact on the thermal properties of concrete. The high replacement of ground granulated blast-furnace slag (GGBS) resulted in a remarkable increase in thermal conductivity. This investigation provides significant conclusions and recommendations that are of practical importance to the construction industry in the UAE to promote sustainability. This research aims at formulating recommendations for the effective use of SCMs in the construction industry in the UAE based on their effects on the thermal properties of concrete.

Synergistic effects of ground granulated blast furnace slag and silica fume on the hydration and compressive strength of extremely low w/b ratio cement pastes

This paper presents results from a comprehensive experimental campaign designed to investigate the synergistic effects of SCMs, specifically, ground granulated blast furnace slag (BFS) and silica fume (SF) on the hydration and compressive strength of ultra-high performance cement pastes (UHPCP). Experiments were performed on 65 mixtures with extremely low w/b ratios (0.16, 0.20) and different SF and BFS replacements under different curing conditions. New insights into the synergistic effects of the SCMs in terms of evolution of portlandite and bound water content, hydration kinetics of UHPCP under standard and elevated curing conditions, and compressive strength are presented. It is demonstrated that effectively controlling the w/b ratio, curing conditions, and importantly the addition of an optimal SF content will favourably influence the hydration and compressive strength of UHPCP. However, the use of high BFS replacement may induce an adverse effect on the hydration and compressive strength of UHPCP. A linear correlation between the bound water content and compressive strength as well as portlandite content is revealed, which serve as valuable indicators for material design. • Underlying hydration mechanisms due to synergistic effects of SCMs are investigated • Synergistic effect by combining SF and BFS improves the strength of UHPCP • Addition of SF to mixtures containing BFS enhances the bound water content • Effectiveness of steam curing is clearly pronounced with higher BFS up to 50% • Good linear correlation between portlandite, compressive strength and bound water

Predicting compressive strength of high-performance concrete with high volume ground granulated blast-furnace slag replacement using boosting machine learning algorithms

Predicting the compressive strength of concrete is a complicated process due to the heterogeneous mixture of concrete and high variable materials. Researchers have predicted the compressive strength of concrete for various mixes using machine learning and deep learning models. In this research, compressive strength of high-performance concrete with high volume ground granulated blast-furnace slag replacement is predicted using boosting machine learning (BML) algorithms, namely, Light Gradient Boosting Machine, CatBoost Regressor, Gradient Boosting Regressor (GBR), Adaboost Regressor, and Extreme Gradient Boosting. In these studies, the BML model’s performance is evaluated based on prediction accuracy and prediction error rates, i.e., R2, MSE, RMSE, MAE, RMSLE, and MAPE. Additionally, the BML models were further optimised with Random Search algorithms and compared to BML models with default hyperparameters. Comparing all 5 BML models, the GBR model shows the highest prediction accuracy with R2 of 0.96 and lowest model error with MAE and RMSE of 2.73 and 3.40, respectively for test dataset. In conclusion, the GBR model are the best performing BML for predicting the compressive strength of concrete with the highest prediction accuracy, and lowest modelling error.

Influence of Fly Ash Denitrification on Properties of Hybrid Alkali-Activated Composites

This article deals with the possibility of partial replacement of blast furnace slag (GGBFS) with fly ash after denitrification (FAD) in alkali-activated materials. Physical-mechanical and durability properties were tested, hydration reaction was monitored, and infrared spectroscopy was performed. Results were compared between mixtures prepared with fly ash without denitrification (FA), and also with a mixture based only on GGBFS. The basic result is that hybrid alkali-systems with FAD show similar trends to FA. The significant effect of fly ash is manifested in terms of its resistance to freeze-thaw processes. Reactions in a calorimeter show a slower development of reactions with increasing replacement of GGBFS due to the lower reactivity of the fly ash. Through testing the leaching resistance, a decrease in flexural strength was found. This may be due to the descaling of the main hydration product, C–(A)–S–H gel. After 28 days of maturation, compressive strengths of all monitored mixtures ranged from 96 to 102 MPa. The flexural strengths ranged from 6.8 to 8.0 MPa. After 28 days of maturation, the higher strengths reached mixtures without replacing GGBFS. In terms of resistance to freeze-thaw processes, the largest decrease (almost 20%) of flexural strength was achieved by a mixture with 30% of GGBFS replacement by FA. No fundamental differences were found for the mixtures in the FTIR analysis.

Correlating strength and durability to time-temperature profiles of high-performance mass concrete

The temperature rise in mass concrete usually leads to premature distresses and early-age cracking. This paper correlates the time-temperature profiles to the mechanical properties and durability of high-performance mass concrete (HPMC). Five types of cement having different specific surface areas (SSA) and granulated blast furnace slag (GBFS) replacement rates are tested. Thirteen thermocouples were inserted at various locations inside a 1-m3 formwork to record the rate of concrete temperature rise, maximum temperature (Tmax), and time needed to attain Tmax. The mechanical properties were characterized by the compressive and flexural strengths, while the durability was evaluated using the drying shrinkage, water permeability, and chloride migration. Experimental results showed that concrete containing fine cement exhibited better strength and durability, yet increased tendency to thermal cracks and drying shrinkage. The partial cement replacement by GBFS reduced the concrete rate of temperature rise and Tmax, which led to reduced shrinkage. Analytical correlations and multivariable linear regression models were developed to predict the effect of SSA, GBFS replacement rate, and 28-day heat of cement hydration on the time-temperature characteristics and durability of HPMC.

A study on the change in frost resistance and pore structure of concrete containing blast furnace slag under the carbonation conditions

In this study, the change in frost resistance and pore structure of concrete containing blast furnace slag with various replacement ratio due to carbonation were investigated. As a result, there is a close relationship between the carbonation speed and 28-day compressive strength in blast furnace slag concrete. The frost resistance, carbonation resistance and scaling resistance of blast furnace slag cement concrete decrease as blast furnace slag replacement ratio increases. Furthermore, due to carbonation, the frost durability of ordinary Portland cement concrete and the concrete with a low replacement ratio of blast furnace slag tends to decrease. However, the concrete with a high replacement ratio of blast furnace slag tends to increase. Under the carbonation conditions, the pore volume decreases due to carbonation of calcium hydroxide, and the pore structure will be coarsened due to carbonation of C-S-H. In addition, it is expected that permeability of concrete is raised and scaling is inhibited due to carbonation, and the surface area with a certain thickness in the carbonated concrete will be scaled due to freeze–thaw.

Effect of volcanic ash as partial replacement of ground-granulated blast-furnace slag based alkaline activated mortar

Volcanic ash obtained from Mount Sinabung is an aluminosilicate material that is generally available deposited in the land of Sinabung. The study focuses to investigate the effect of volcanic ash as partial replacement of ground-granulated blast-furnace slag (GGBFS) based alkaline activated mortar (AAM) in varying six ratios from 10 wt.% to 60 wt.% in terms of the compressive strength (CS) and structural characteristics. The six-mixture design of AAM was conducted with addition of alkaline activator solution (AAS) to solid material. The AAS were prepared from a combination of 10 M NaOH and Na2SiO3, whereas, solid materials consisted of GGBFS, VA and fine aggregates. The results of the experiments were analysed by CS at the age of 7, 28, and 56 days and supported by SEM characterization for the optimum mixture. The results have revealed that the least significant factor in terms of compressive strength value is the addition of volcanic ash content whereby the highest value of 93.50 MPa produced by Va 10% and the lowest of 35.80 MPa from Va 60% for all of ages day. In addition, the regression linear values show the overall compressive strength decreased slowly over the ages. Contrastingly, the addition of volcanic ash higher than 40% exhibited an increment of compressive strength. Based on SEM observation dense and continuous microstructure was observed which reflects a high degree of polymerization reactions. At the same time, no cracks were observed in the surface microstructure that shows proper aggregate-binder bonding that influences the compressive strength results finding.

Experimental studies on partial replacement of E-waste and Blast Furnace Slag in concrete

The purpose of this project is to delay the corrosion of concrete structure in marine environment. Here the PCB E-waste is used as the material for the purpose of replacement without reducing the properties of the concrete and its durability and strength. The curing process of cubes, cylinders and flexural beams are done in the artificially prepared marine environment. The maximum compressive strength was attained at 15% partial replacement of GGBS and E –Waste within 28 days. The flexural and split tensile strength also reaches their maximum level by replacing 15% of GGBS and E – Waste in concrete. At the same time the chloride and sulphate attack of the partially replaced concrete is gradually reduced the weight and compressive strength within 30 days in the marine environment. From the above studies, it was concluded that the GGBS and E –Waste can be used up to 30% for getting the maximum strength.

Influence of fibers on fresh properties and compressive strength of geo-polymer concrete

Geopolymer concrete (GPC) is a sustainable construction material that can be used as a substitute for conventional cement concrete. Several factors influence the performance of GPC such as, the type of binder material used, the molar concentration of the activator solution, and the curing conditions. The main purpose of this work is to develop fiber reinforced GPC by utilising various fibers that to reduce brittleness. The proposed work is divided into two phases. In the first phase, experiments are conducted to evaluate the significant impact of partial replacement of Ground Granulated Blast Furnace Slag (GGBS) with low-calcium fly ash on workability and compressive strength of GPC optimizing the amount of GGBS required for the development of M35 and M40 grade GPC under ambient curing. In the second phase, the performance of crimped steel fiber, polypropylene fiber and basalt fiber in terms of workability and compressive strength were evaluated. Crimped steel fiber containing by volume of binder (0.4%, 0.45%, 0.5%, 0.55% and 0.6%), polypropylene fiber containing by volume of binder (0.05%, 0.1%, 0.15%, 0.2% and 0.25%) and basalt fiber containing by volume of binder (0.1%, 0.15% 0.2%, 0.25%, 0.3% and 0.35%) are used in the experiment. NaOH with 8 M and 12 M with Na2SiO3 were used as an alkaline solution to develop GPC and cured in the ambient curing for 7 days and 28 days respectively. It was observed that increase in the percentage of GGBS decreased the workability, but the compressive strength is increased. The effect of fibers on workability and compressibility has been observed, and it has been found that workability decreases with the increase of fibers in the GPC. Compare to crimped steel fiber, basalt fiber the workability of GPC is highly affected due to the addition of polypropylene fiber. In comparison crimped steel fiber and polypropylene fiber, concrete with salt fiber exhibited higher compressive strength.

Optimization of Dune Sand-Slag Blended Geopolymer Mortar Using Taguchi Method

Achieving optimum performance of geopolymer mortar intended for structural and repair applications is a complex task with various factors being considered prior to production. This study explores the influence of mix design parameters on the fresh and hardened properties of geopolymer mortar made with treated dune sand (TDS) and granulated blast furnace slag (BFS). A total of nine geopolymer mortar mixtures were designed following the Taguchi method for four factors, each with three levels. These factors included BFS replacement rate by TDS, alkali-activator solution to binder ratio (AAS/B), sodium silicate-to-sodium hydroxide ratio (SS/SH), and sodium hydroxide (SH) molarity. The investigated performance quality criteria were flowability, compressive strength, water permeability, and carbon dioxide footprint. The effect of various factors on the responses was assessed through ANOVA while determining the signal-to-noise (S/N) ratios to seek the optimum proportions of mixtures. Results revealed that a mix made with TDS replacement, AAS/B, SS/SH, and SH molarity of 25%, 0.5, 1.5, and 14 M yielded superior performance.

Enduring performance of alkali-activated mortars with metakaolin as granulated blast furnace slag replacement

In the construction industries worldwide, improving the materials durability and achieving sustainability are the main goal. Owing to their excellent strength performance various alkali-activated binders can be one of the alternative solutions to the polluting traditional cement. Currently, ground blast furnace slag (GBFS) is the major base material used in the alkali-activated binders. High drying shrinkage and low resistance to sulfuric acid attack affect negatively the durability performance and life span of alkali-activated paste, mortars, and concretes made from GBFS. Thus, a series of alkali-activated mortars (AAMs) were designed with various contents (5, 10, 15, 20 and 25, mass%) of metakaolin (MK) as GBFS replacement to improve their strength performance. In addition, the strength and durability performance of the designed mixes were compared with the control mixture prepared using 100% of GBFS. The impact of varying MK level on the long-term performance such as compressive strength, porosity, resistance to sulfuric acid attacks, wet-dry cycles, drying shrinkage, and carbonation were evaluated. Various recommended standards were followed to cast the specimens in different shapes (cubes, cylinders, and prisms) and sizes. Mortar containing 10% of MK as GBFS replacement showed the highest compressive strength (63.4 MPa) at 28 days of curing age. Furthermore, the inclusion of MK as GBFS replacement was shown to improve the AAMs durability performance wherein the drying shrinkage was reduced and the resistance to aggressive environments was increased. The specimens containing 5% and 10% of MK revealed a lower porosity and carbonation depth compared to the control specimen. It was concluded that the proposed AAMs due to their long-term stability can be the sustainable and potential substitutes to the traditional construction materials.

Effect of Ground Granulated Blast Furnace Slag Replacement Ratio on Structural Performance of Precast Concrete Beams.

This study was conducted to investigate the effect of ground granulated blast furnace slag on the structural performance of precast concrete beams, evaluating the flexural, shear and bonding performance by using the replacement ratio of the ground granulated blast furnace slag as a variable. The design strength of the concrete was set at 45 MPa in consideration of the characteristics of precast concrete products, and the replacement ratio of the ground granulated blast furnace slag to replace cement was 30 to 70%. The experimental results showed that all specimens had similar behavioral characteristics regardless of the replacement ratio of the ground granulated blast furnace slag. Comparison of the prediction results obtained by ACI 318-19 and EC 2 showed that the mean flexural strength and shear strength were higher than 1.19 and 1.43, respectively, and the mean bond strength was 1.57, satisfying the required performance. Therefore, the experimental results showed that in using the ground granulated blast furnace slag as an admixture for precast concrete, the cement replacement ratio may be increased up to 70% without causing any problems in securing the structural performance. Summarizing the results of the present study, a ground granulated blast furnace slag replacement ratio of 50% or lower may be reasonably applied.

Numerical analysis of thermal cracking estimation of mass concrete with GGBS at an early age

At an early age, the temperature rise in mass concrete is attributable primarily to the propagation of heat due to an exothermic reaction of cementitious materials and water. The temperature variation in the mass concrete between the core and its surfaces results in the development of thermal stresses. It might occur cracking if these stresses surpass the gained tensile strength of concrete. The paper compares experimental and numerical outcomes of heat generation in concrete mould 0.15 m × 0.15 m × 0.15 m in size. Four concrete mixtures with ground granulated blast-furnace slag (GGBS) replacement to cement 0%, 10%, 30%, and 50% were used in the study. Virtual Cement and Concrete Testing Laboratory (VCCTL) software was used for obtaining the degree of hydration and adiabatic temperature of the four mixtures. Finite element modeling of these mixtures observed good agreement with experimental testing captured by the thermometer. Following that, numerical simulation was utilized to study the effect of the block size (cubic models with edge length 0.5 m, 1.0 m, 2.0 m, and 3.0 m) on temperature rise and the associated risk of cracking in mass concrete blocks.