Blast Furnace Slag Concrete Research Articles

Evaluating the durability performance of concrete containing clastic sand and GGBS

The manufacturing process of materials utilized in concrete production has environmental implications. The production of cement releases significant amounts of greenhouse gases, while the extraction of aggregates and sand poses challenges to the natural environment. To minimize the aforementioned challenges researchers are suggested to utilize industrial by-products as a partial alternative for these materials Fly ash, stone dust, GGBS, silica fume, and metakaolin are widely utilized alternatives to construction materials. The specific use of clastic sand as a partial substitute for fine aggregate has recently gained popularity . However, studies on the characteristics of concrete prepared using cementitious materials and clastic sand are very few. In this work, the effect of clastic sand with ground granulated blast furnace slag concrete is being investigated. The GGBS is added in place of cement from 0% to 45%. Further, clastic sand is added in different proportions in GGBS concrete. The electrical resistivity, water absorption, acid attack, and micro-structural studies are carried out on all mixes to know the durability properties. The results confirm that the addition of GGBS as a cementitious material enhances durability. The inclusion of 35% of GGBS as a substitute for cement is optimum for enhancing durability. Further, the inclusion of 35% GGBS as a cement substitute and 20% clastic sand shows a dense matrix and optimum results in enhancing durability. This is due to the pozzolanic activity of GGBS and clastic sand works as filler materials. This investigation suggests utilizing clastic sand along with GGBS as a cementitious material.

Time-depth dependent chloride diffusion coefficients of self-compacting concrete

Chloride attack severely impacts the performance of reinforced concrete. The total and free chloride ion concentrations (CICs) of self-compacting concrete (SCC) prepared with three supplementary cementitious materials (SCMs) - fly ash (FA), blast furnace slag (BS), and silica fume (SF) – were measured through the accelerated salt immersion tests. The apparent chloride diffusion coefficients (CDCs) at any exposure time and erosion depth were calculated using the Boltzmann-Matano method. The influence of the type and content of SCMs, the water-binder ratio (W/B), and the type of salt solution on CICs and CDCs were investigated. Both introducing SCMs and reducing W/B effectively reduced the CIC. The SCM that most effectively reduced CIC was SF, followed by BS and then FA. Free CICs were reduced to a greater degree than total CICs in FA and BS concrete, but the opposite was true for SF concrete. Presence of calcium chloride in salt solution increased total CICs while reducing free CICs. Apparent free CDC dropped over exposure time and initially increased with erosion depth but eventually stabilized. A model of apparent free CDC considering the time-depth dependence was created, which shows that time reduction factors of CDC is larger in SCM-containing SCC than in control SCC.

Mechanical properties prediction of blast furnace slag and fly ash-based alkali-activated concrete by machine learning methods

In this paper, 871 data were collected from literature and trained by the 4 representative machine learning methods, in order to build a robust compressive strength predictive model for slag and fly ash based alkali activated concretes. The optimum models of each machine learning method were verified by 4 validation metrics and further compared with an empirical formula and experimental results. Besides, a literature study was carried out to investigate the connection between compressive strength and other mechanical characteristics. As a result, the gradient boosting regression trees model and several predictive formulas were eventually proposed for the prediction of the mechanical behavior including compressive strength, elastic modulus, splitting tensile strength, flexural strength, and Poisson’s ratio of BFS/FA-AACs. The importance index of each parameter on the strength of BFS/FA-AACs was elaborated as well.

Fracture toughness evaluation of ground granulated blast furnace slag concrete using experimental study and machine learning techniques

The relationship between mix design and fracture properties of ground granulated blast furnace slag (GGBFS) concrete is complex and influenced by many factors, such as mixture composition. This study evaluates the fracture toughness under mode-I, mode-II, and mixed-mode, performed on centrally straight-notched Brazilian discs. An experimental program generated an extensive database of the fracture toughness of GGBFS mortar, consisting of 143 specimens with different mix designs under different loading angle conditions. Then, a combination of support vector regression (SVR) algorithm and genetic algorithm (GA) as hyperparameter tuner was conducted to develop models for fracture toughness. The SVR algorithm was trained with Radial Basis Function (RBF), polynomial, sigmoid, and linear kernel functions. Based on the Taylor diagram, the models demonstrated robust performance in predicting fracture toughness. The performance metrics indicate that the RBF function is the most reliable model, with R2-score 0.95 and 0.94 for KIC and KIIC, respectively. The importance score of input features was determined with the permutation importance function. The angle between the crack and loading direction is the most influential parameter in the models.

Mechanical and durability performance of sustainable concretes containing conventional and emerging supplementary cementitious materials

This paper presents a comparative study on the mechanical and durability properties of concrete mixtures containing conventional supplementary cementitious materials (SCMs) and emerging alternatives (i.e., volcanic ash, volcanic ash-limestone blend, and metakaolin-limestone blend), with an emphasis on the latter. To enable effective comparison, identical volumetric substitution levels (30%) of SCMs along with a constant binder and aggregate volumes were employed. The metakaolin-limestone concrete performs the best among all types of concretes in terms of strength development, water absorption capacity and chloride penetration resistance. The incorporation of volcanic ash though reduces the compressive strength of concrete and increases water absorption capacity considerably compared to the reference Portland cement concrete, and its chloride diffusion coefficient is only about half of that of the reference concrete. In addition, the concretes containing volcanic ash or volcanic ash-limestone show better performance in controlling the potential alkali-silica reaction-induced expansion than the reference concrete and ground granulated blast-furnace slag concrete.

Experimental study on mechanical properties of concrete using mineral admixtures

An experimental study on the compact effects of mineral admixtures on the properties of mechanical regarding concrete is presented in this abstract. Fly ash and silica fume were two examples of mineral admixtures that were included in the concrete mixes. Parameters like compressive strength, tensile strength, and durability were tested. The findings shed light on how mineral admixtures can improve the properties of concrete.The benefits of using admixtures such fly ash, silica fume, and granulated blast furnace slag in concrete are shown in this research. Various mechanical parameters, including compression, split tensile, and flexural strength, are measured for specimens of various classes. The M35 grade samples include fly ash (at 0.5, 0.10, and 0.15 concentrations), silica fume (at 0.5, 0.10, and 0.15 concentrations), and granulated blast furnace slag (at 0.5, 0.10, and 0.15 concentrations), all in lieu of cement. The ratio of water to cement used in all tests was 0.45. The chemical activity is slowed and the density is increased thanks to the ground granulated blast furnace sand. The use of a variety of admixtures in concrete results in improved performance in that material's construction. Compression, split tensile strength, and flexural strength are only some of the mechanical parameters that may be measured after 28 days.Therefore the findings are able to provide and compile valuable insights into the enhancement of “concrete properties” through the utilization of mineral admixtures. With the help of “incorporating mineral additives” like fly ash and silica fume into the concrete mixes, a series of fundamental tests were conducted and approved for the evaluation of parameters including compressive strength, tensile strength, and durability.

A mix design methodology of blast furnace slag and fly ash-based alkali-activated concrete

Although the application of blast furnace slag and fly ash-based alkali-activated concrete (BFS/FA-AAC) has both economic and environmental benefits, it is limited by the lack of a straightforward mix design method. In this paper, an experiment was conducted to investigate the effect of control factors, including the Na2O/binder ratio, the SiO2/Na2O ratio, the BFS/binder ratio, the water/binder ratio, and the water content on the workability (slump and rheology) of BFS/FA-AAC, and the effect of control factors include the Na2O/binder ratio, the SiO2/Na2O ratio, the BFS/binder ratio, the water/binder ratio, and the curing time on the compressive strength of BFS/FA-AAC. As a result, the influence degree and mechanism of each control factor on the performance of BFS/FA-AAC were quantitively explored and the accuracy of an empirical compressive strength formula was validated. Based on that, a practical mix design method of BFS/FA-AAC was eventually established. It is found that the mixture composition and content of paste can significantly influence the workability of BFS/FA-AAC. The compressive strength of BFS/FA-AAC is determined by control factors when the water content is within 160–195 kg/m3. The mechanical predictive method of BFS/FA-AAC is proven of high accuracy. The mixture designed by this methodology exhibits satisfied fresh and hardened performance as well as high environmental benefits.

Characterization study of geopolymer concretes fabricated with clinker aggregates

Geopolymers are a new generation of building material that has recently been popular in reducing carbon emissions. As a result of its amorphous alumina-silicate-based reaction product, it has many superior properties. This study investigated the mechanical and physical properties and high-temperature resistance of ground-granulated blast furnace slag and metakaolin-based geopolymer concrete fabricated with clinker aggregates produced in a short curing time (8 h). In alkali activators, the sodium silicate to sodium hydroxide (SS/SH) mass ratios were 2, 2.25, 2.5 and 2.75. Two curing methods were used, namely ambient (25 °C) and oven curing (80 °C). The observed unit weights vary between 2275–2392 kg/m3 for the samples of the geopolymeric composites. Porosity and water absorption vary between 4.92 and 8.84% and 3.58–7.26%, respectively. The heat curing application decreased the mixtures' water absorption, unit weight, and porosity values. The compressive strength of the samples subject to ambient curing varied between 39.2 and 59.8 MPa. Withal, the samples cured at 80 °C for 8 h were between 66.9 and 112.4 MPa. The increased SS/SH ratio also increased the observed strength values. Capillary water absorption of all samples is below 0.6 kg/m2. Heat-cured geopolymers decreased capillary water absorption to 0.1 kg/m2. The weight loss after high temperature decreased as the SS/SH ratio increased. The N-A-S-H gel in the zeolitic structure was observed in SEM analysis. The FT-IR analysis visualized the carbonation in the heat-cured mixtures. As a result, over 100 MPa compressive strength values were observed with the clinker aggregates at 80 °C after 8 h of curing time. Withal, a high-temperature refractory composite was developed with the clinker aggregates. Moreover, the nuclear radiation shielding abilities of geopolymer concretes were investigated experimentally. The gamma shielding parameters of the samples were evaluated by transmission measurements in the range of 0.081–0.661 keV. Also, neutron dose measurements were performed, and the samples produced as neutron attenuator capacity was evaluated. The radiation shielding capabilities were improved slightly with increasing sodium silicate solution content.

Autogenous deformation induced- stress evolution in high-volume GGBFS concrete: Macro-scale behavior and micro-scale origin

This study aims to experimentally investigate the autogenous deformation and the stress evolution in restrained high-volume ground granulated blast furnace slag (GGBFS) concrete. The Temperature Stress Testing Machine (TSTM) and Autogenous Deformation Testing Machine (ADTM) were used to study the macro-scale autogenous deformation and stress evolution of high-volume GGBFS concrete with w/b ratios of 0.35, 0.42, and 0.50. The early-age cracking (EAC) risk (quantified by stress-strength ratio) and stress relaxation were analyzed extensively based on ADTM and TSTM results. Furthermore, Environmental Scanning Electron Microscopy (ESEM), X-ray Diffraction (XRD), and Mercury Intrusion Porosimetry (MIP) were conducted to explore the micro-scale origin of the autogenous deformation of high-volume GGBFS concrete, which supports the observations on the macroscale measurement of TSTM/ ADTM tests. This study finds that the ettringite formation in the first two days results in autogenous expansion, which can delay the appearance of tensile stress. The magnitude of autogenous expansion depends on the compatibility of ettringite content and pore size. The w/b ratio of 0.42 turns out to be optimal because it produces the highest amount of ettringite and results in the highest autogenous expansion. In comparison, the w/b ratio of 0.35 introduces significant autogenous shrinkage after the expansion peak and therefore corresponds to a high early-age cracking risk.

Development of Sustainable Concrete from Blast Furnace Slag and Recycled Concrete Sand

Development of Sustainable Concrete from Blast Furnace Slag and Recycled Concrete Sand

Using Artificial Intelligence and Machine Learning Model for Prediction of Uniaxial Compressive Strength of GGBS Concrete

Ground Granulated Blast-furnace Slag (GGBS) concrete is sustainable and also proven to show enhanced properties such as reduced heat of hydration, refinement of pore structure and increased resistance to corrosion and chemical attacks when compared with Ordinary Portland Cement concrete. Uniaxial compressive strength (UCS) and enhanced properties of the GGBS concrete are dependent on the proportions of GGBS and other elements in the mix. It is essential to accurately predict the UCS of the blended mix. Developments in computer hardware and the easy availability of research data made artificial intelligence and machine learning (AI & ML) prediction techniques feasible. In this study AI & ML techniques namely, linear regression, lasso regression and ridge regression are used to predict the UCS of GGBS concrete. Algorithms are trained using data collected from various standard publications. All data points are cleaned and then normalized with standard scalar function to avoid biased predictions. Root Mean Squared Error, Mean Squared Error, Mean Absolute Error and Coefficient of Determination for all three techniques are found to be almost identical. The above-mentioned AI & ML models have high prediction accuracy. Hence, based on the results AI & ML algorithms specified above can be reliably used in the above-mentioned GGBS concrete.

Salt-scaling resistance of highly durable RC slabs utilizing GGBS concrete with expansive additive

In recent years, the utilization expansive additive for ground granulated blast furnace slag (GGBS) concrete has been confirmed to be indispensable to reduce the early-age thermal tensile stress, which results in successful crack mitigation in several highly durable reinforced concrete (RC) slabs in Japan. However, various investigations have cited that the application of large amounts of expansive additive might reduce the salt-scaling resistance of durable RC slabs. This study experimentally investigates the salt-scaling resistance on the top surface of highly durable RC deck slab specimens by utilizing GGBS concrete with applicable dosages of expansive additive. Test results revealed that the proposed salt-scaling method modified based on ASTM C672 with a 6 h cycle and with more severe scaling temperatures at a minimum and maximum of ± 35 °C can reasonably reduce the experimental duration and effort for practical purposes. Moreover, although the salt-scaling resistance of the highly durable RC slab specimens decreased as the dosage of the expansive additive increased, acceptable salt-scaling resistance was obtained in the specimens with 20 and 25 kg/m3 expansive additive dosages.

Experimental investigation on high volume ground granulated blast furnace slag concrete

The present confront among the construction industry is to curtail the production of the ordinary Portland cement (OPC), which is directly responsible to the emission of harmful gases like CO2 during the manufacturing and also depletion of natural resources like lime stone, coal etc. The present investigation is focused to develop the sustainable concrete using complementary cementing materials (CCMs) for the sustainable environment. Ground granulated blast furnace slag (GGBS) is one among the sustainable alternatives for ordinary Portland cement (OPC) to produce green concrete and because of its high calcium silicate content it has excellent cementious content and has been used in the construction industry for years as a replacement for ordinary Portland cement (OPC). The paper presents the performance of the Binary concrete made by replacing the OPC with high volume GGBS up to 70%. In total 6 binary mixtures and conventional mix were prepared for M40 grade of concrete. Flow characteristics and strength properties (compression, split tensile and flexural strength) are determined for both conventional and binary concrete at the age of 7, 28, 60, 90 days. The test results proved that the binary concrete had considerable performance regarding workability and strength of the binary concrete over conventional mix.

Autogenous shrinkage of fly ash and ground granulated blast furnace slag concrete

Supplementary cementitious materials (SCMs) are widely used to reduce the cement content to achieve economic and environmental objectives. As a result, understanding the shrinkage of blended cement-based concrete is essential. In total, 21 concrete mixes were produced with type general purpose cement and with cement replacements of 30% by fly ash, 40% and 60% by ground granulated blast furnace slag (GGBFS). The concrete compressive strength ranged from 25 MPa to 100 MPa. Experimental results were also compared with the predictions by models. Additional tests on pastes with the same SCM content were conducted to investigate both autogenous and chemical shrinkage in relation to their time-dependent pore structure refinement. For concretes with strength below 50 MPa, no significant difference in autogenous shrinkage could be observed between the different blends up to 28 days. However, the autogenous shrinkage of GGBFS concrete increased significantly after 28 days, being about 50% higher than all other concretes at 100 days. This late increase in autogenous shrinkage between 28 and 100 days can be attributed to pore refinement processes. No clear difference was observed for GGBFS concretes with strength greater than 50 MPa. Autogenous shrinkage of fly ash concretes was overall equivalent to that of reference concretes.

Soft computing models to predict the compressive strength of GGBS/FA- geopolymer concrete

A variety of ashes used as the binder in geopolymer concrete such as fly ash (FA), ground granulated blast furnace slag (GGBS), rice husk ash (RHA), metakaolin (MK), palm oil fuel ash (POFA), and so on, among of them the FA was commonly used to produce geopolymer concrete. However, one of the drawbacks of using FA as a main binder in geopolymer concrete is that it needs heat curing to cure the concrete specimens, which lead to restriction of using geopolymer concrete in site projects; therefore, GGBS was used as a replacement for FA with different percentages to tackle this problem. In this study, Artificial Neural Network (ANN), M5P-Tree (M5P), Linear Regression (LR), and Multi-logistic regression (MLR) models were used to develop the predictive models for predicting the compressive strength of blended ground granulated blast furnace slag and fly ash based-geopolymer concrete (GGBS/FA-GPC). A comprehensive dataset consists of 220 samples collected in several academic research studies and analyzed to develop the models. In the modeling process, for the first time, eleven effective variable parameters on the compressive strength of the GGBS/FA-GPC, including the Activated alkaline solution to binder ratio (l/b), FA content, SiO2/Al2O3 (Si/Al) of FA, GGBS content, SiO2/CaO (Si/Ca) of GGBS, fine (F) and coarse (C) aggregate content, sodium hydroxide (SH) content, sodium silicate (SS) content, (SS/SH) and molarity (M) were considered as the modeling input parameters. Various statistical assessments such as Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the Coefficient of determination (R2) were used to evaluate the efficiency of the developed models. The results indicated that the ANN model better predicted the compressive strength of GGBS/FA-GPC mixtures compared to the other models. Moreover, the sensitivity analysis demonstrated that the alkaline liquid to binder ratio, fly ash content, molarity, and sodium silicate content are the most affecting parameter for estimating the compressive strength of the GGBS/FA-GPC.

Influence of sustained compressive load on the carbonation of concrete containing blast furnace slag

Carbonation of concrete, in which 0%, 50% and 70% of cement was replaced by blast furnace slag (BFS), under different levels of sustained compressive load (0, 0.25, 0.5 and 0.75 times the breaking load) was investigated. The results show that the carbonation rate first decreases with load level and then above a threshold value (approximately 0.25–0.5 times the breaking load) increases with load level. The carbonation rate of BFS concrete becomes closer to that of Portland cement concrete under sustained compressive load. An investigation of the load-induced microstructure changes showed that the densification effect dominates in the carbonated zone in terms of lower porosity, denser interfacial transition zone, lower crack width and autogenous healing of fine cracks. The cracking effect plays a more significant role in the non-carbonated zone and leads to a notable increase in the carbonation rate at a high load level. The average major principle strain obtained by digital image correlation can be used to evaluate the combined effect of densification and cracking.

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.

Hydration and Microstructure of High-Volume Ground Granulated Blast Furnace Slag Concrete Incorporating Metakaolin

In order to relieve the carbon emission of concrete industry, the application of high-volume ground granulated blast furnace slag (HVGGBFS) concrete is one of low cost and effective methods, but its properties develop slowly which needs to be solved. The impact of metakaolin (MK) on the microstructure and hydration evolution of HVGGBFS concrete has been investigated through the compressive strengths, non-evaporable water, morphology and nanoindentation. The results show that the non-evaporable water evolution of HVGGBFS concrete with MK has a similar trend with the compressive strength evolution. The use of 10% MK increases the compressive strengths of HVGGBFS concrete, and from the beginning of 28 days, its strengths are higher than those of the control concrete without GGBFS and MK. The use of 10% MK replacing cement reduces pores and unhydrated particles of HVGGBFS concrete, and however, increases high density calcium-silicate-hydrate (HD C–S–H) and ultra-high density C–S–H (UHD C–S–H), which may be attributed to C–S–H generated by the pozzolanic reaction of MK largely being HD C–S–H and UHD C–S–H.

Stress evolution in restrained GGBFS concrete due to autogenous deformation: bayesian optimization of aging creep

Stress evolution of restrained concrete is a significant direct index in early-age cracking (EAC) analysis of concrete. This study presents experiments and numerical modelling of the early-age stress evolution of Ground granulated blast furnace slag (GGBFS) concrete, considering the development of autogenous deformation and creep. Temperature Stress Testing Machine (TSTM) tests were conducted to obtain the autogenous deformation and stress evolution of restrained GGBFS concrete. By a self-defined material subroutine based on the Rate-type creep law, the FEM model for simulating the stress evolution in TSTM tests was established. By characterizing the creep compliance function with a 13-units continuous Kelvin chain, forward modelling was firstly conducted to predict the stress development. Then inverse modelling was conducted by Bayesian Optimization to efficiently modify the arbitrary assumption of the codes on the aging creep. The major findings of this study are as follows: 1) the high autogenous expansion of GGBFS induces compressive stress at first hours, but its value is low because of high relaxation and low elastic modulus; 2) The codes highly underestimated the early-age creep of GGBFS concrete. They performed well in prediction of stress after 200 h, but showed significant gaps in predictions of early-age stress evolution; 3) The proposed inverse modelling method with Bayesian Optimization can efficiently adjusted the aging terms which produced best modelling results. The adjusted creep compliance function of GGBFS showed a much faster aging speed at early ages than the one proposed by original codes.

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.