Granulated Blast Furnace Slag Research Articles

Effect of carbon dioxide mineralization curing on mechanical properties and microstructure of Portland cement–steel slag–granulated blast furnace slag ternary paste

To investigate the synergistic effects of steel slag (SS) and granulated blast furnace slag (GBFS) on cementitious systems during carbon dioxide (CO2) mineralization curing. Ternary paste specimens containing SS, GBFS, and Portland cement (PC) were prepared to analyze the influence of drying pre-treatment time and SS–GBFS mixing ratios on mechanical properties, CO2 fixation rate, and microstructure evolution. Results emphasize the significance of appropriate drying pre-treatment in enhancing mineralization degree and compressive strength. At 60 °C drying pre-treatment temperature, extending drying pre-treatment time up to 12 h enhances both compressive strength and CO2 fixation rate. However, beyond 12 h, a decline is observed in both parameters. Moreover, under the optimal drying pre-treatment time, the compressive strength of ternary paste specimens post-mineralization increases with higher SS content, with SS exerting a more pronounced positive effect on CO2 fixation rate and compressive strength compared to GBFS. After 4 h of mineralization curing, specimens with 50% SS and 10% GBFS demonstrate a 13.16% increase in compressive strength and a 9.16% increase in CO2 fixation rate compared to specimens with 10% SS and 50% GBFS. Microscopic test results reveal that the primary crystalline product in ternary paste specimens after mineralization is calcite, with traces of aragonite. The SS–GBFS mixing ratio has minimal effect on the type of reaction products but has a predominant influence on the total content and crystallinity of calcarea carbonica.

Enhanced Concrete Performance and Sustainability with Fly Ash and Ground Granulated Blast Furnace Slag – A Comprehensive Experimental Study

Enhanced Concrete Performance and Sustainability with Fly Ash and Ground Granulated Blast Furnace Slag – A Comprehensive Experimental Study

Production of low-CO2 ternary binder using red sandstone, cement, and granulated blast furnace slag: A comprehensive performance analysis

Red sandstone is rich in reserves, and using it as a mineral admixture to partially replace cement can save cement consumption and reduce carbon dioxide emissions. This study uses spectral characterization, electron microscopy image analysis, mechanical property testing and other methods to study the fluidity, compressive strength, heat of hydration, carbonation degree, microstructure and thermal damage of composite cement-based materials containing red sandstone and slag. The experiment results showed that in ternary mixed cement, the composite cement mixed with 5% slag and 10% red sandstone shows similar flow properties to cement paste. Moreover, as the mineral content (red sandstone and slag) increases, the dissolution peak of the Al phase appears earlier, and the degree of carbonation increases. Furthermore, the CO2 emissions per unit strength gradually decrease. After 28 days of curing, thermal damage experiments demonstrated that the strength of the sample increases by more than 3.6% when the mineral content is greater than 15% at 200℃. Samples were subjected to 600 °C and 900 °C, and the strength of the red sandstone sample with a content of 15% decreased significantly. Moreover, as the temperature increases to (600 °C and 900 °C), the lattice of CnS becomes more and more ordered.

Biomass ash waste from agricultural residues: Characterisation, reactivity and potential to develop one-part geopolymer cement

Biomass is burned to generate heat and electricity. The use of biomass fuel has acquired great importance in the last years owing to its carbon-neutral nature. As a result, there is a massive build-up of biomass ash that will keep growing for decades to come. This study uses biomass ash waste to fabricate cements for construction and it presents a “zero fossil energy consumption and zero waste generation" approach to cement production. We measure the reactivity of crop biomass ash (CBA) from a power plant and the properties of one-part, CBA-slag geopolymer cements made with it.CBA has pozzolanic reactivity and potential as precursor for geopolymer fabrication. Up to 30% of CBA can be blended with ground granulated blast furnace slag (GGBS) to produce sound, one-part geopolymers activated with sodium carbonate and/or sodium silicate. Beyond this ash threshold, the geopolymer matrix experiences a strength reduction due to insufficient cement content. A one-part geopolymer consisting of 30% CBA and 70% GGBS activated with 10% sodium carbonate achieved a compressive strength of 30.70MPa at 28 days of curing at ambient temperature. However, it exhibited a prolonged setting, taking up to 5hours to initially set and 8hours to finally set. Adding a sodium silicate activator significantly improved mechanical performance and accelerated setting. A formulation activated with 20% sodium silicate and 5% sodium carbonate reached a compressive strength of 46.09MPa at 28 days, with setting times reduced to 57minutes for the initial setting and 1hour 15minutes for the final setting. The sodium silicate activator enhanced hydrate formation and facilitated polymerization thereby accelerating the set and enhancing mechanical performance.Owing to the low carbon emission factor of CBA, the one-part CBA-GGBS has a low carbon footprint, which can reduce carbon emission by 80% in comparison to PC-GGBS (CEM II) mortar with a similar compressive strength. The CBA-GGBS geopolymer is economically feasible, applicable, and market attractive due to its low cost compared with equivalent PC products.

Experimental Study on Workability, Strength & Durability of Geopolymer Concrete with use of Fly ash, Ground Granulated Blast Furnace Slag & Silica Fume

Abstract: Geopolymer concrete, crafted from a blend of Fly Ash, GGBS, and Silica Fume activated by sodium silicate and sodium hydroxide, demonstrates excellent workability and strength over time. It proves resilient against acid, chloride, water absorption, and carbonation, making it a sustainable choice for construction projects seeking durability and performance. These qualities position geopolymer concrete as a promising alternative to traditional concrete methods.

Dynamic Mechanical Performance of Sulfate-Bearing Soils Stabilized by Magnesia-Ground Granulated Blast Furnace Slag

Sulfate soils often caused foundation settlement, uneven deformation, and ground cracking. The distribution of sulfate-bearing soil is extensive, and effective stabilization of sulfate-bearing soil could potentially exert a profound influence on environmental protection. Ground granulated blast furnace slag (GGBS)–magnesia (MgO) can be an effective solution to stabilize sulfate soils. Dynamic cyclic loading can be used to simulate moving vehicles applied on subgrade soils, but studies on the dynamic mechanical properties of sulfate-bearing soil under cyclic loading are limited. In this study, GGBS-MgO was used to treat Ca-sulfate soil and Mg-sulfate soil. The swelling of the specimens was analyzed by a three-dimensional swelling test, and the change in compressive strength of the specimens after immersion was analyzed by an unconfined test. The dynamic elastic properties and energy dissipation of GGBS-MgO-stabilized sulfate soils were evaluated using a fatigue test, and the mineralogy and microstructure of the stabilized soils were investigated by X-ray diffraction and scanning electron microscopy. The results showed that the maximum swelling percentage of stabilized Ca-sulfate soil was achieved when the GGBS:MgO ratio was 6:4, resulting in an expansion rate of 14.211%. In contrast, stabilized Mg-sulfate soil exhibited maximum swelling at GGBS:MgO = 9:1, with a swelling percentage of 5.127%. As the GGBS:MgO ratio decreased, the dynamic elastic modulus of stabilized Ca-sulfate soil diminished from 2.8 MPa to 2.69 MPa, and energy dissipation reduced from 0.02 MJ/m3 to 0.019 MJ/m3. Conversely, the dynamic elastic modulus of stabilized Mg-sulfate soil escalated from 2.16 MPa to 6.12 MPa, while energy dissipation decreased from 0.023 MJ/m3 to 0.004 MJ/m3. After soaking, the dynamic elastic modulus of Ca-sulfate soil peaked (4.01 MPa) and energy dissipation was at its lowest (0.012 MJ/m3) at GGBS:MgO = 9:1. However, stabilized Mg-sulfate soil exhibited superior performance at GGBS:MgO = 6:4, with a dynamic elastic modulus of 0.74 MPa and energy dissipation of 0.05 MJ/m3. CSH increased significantly in the Ca-sulfate soil treated with GGBS-MgO. The generation of ettringite increased with the decrease in the GGBS-MgO ratio after immersion. MSH and less CSH were formed in GGBS-MgO-stabilized Mg-sulfate soil compared to Ca-sulfate soils. In summary, the results of this study provide some references for the improvement and application of sulfate soil in the field of road subgrade.

Effect of metakaolin content and shape design on strength performance of lightweight rubberized geopolymer mortars incorporated slag-waste glass powders

Lightweight rubberized geopolymer (LRGP) has gained attention due to its economic, engineering, and environmental benefits. With the rising human demands, the need for alternative materials to meet the requirements of infrastructural expansion, and global industrialization required. Based on those facts, this study aimed to develop of lightweight geopolymer mortars using wastes rubber as fine aggregate (WRA) to replace the natural aggregates, which metakaolin (MK), wastes bottle glass (WBG) and granulated blast furnace slag (GBFS) used as precursor materials with alkaline activator contained low molarity of sodium hydroxide solution and sodium silicate and cured at ambient temperatures. The effect of WRA on physical, mechanical, and microstructural properties of metakaolin-based rubberized geopolymer has been evaluated by using several tests such as compressive, flexural and tensile strength. As well as morphology and chemical reaction on LRGP by using AFM, FESEM, EDX, FTIR and XRD tests. In addition, a sustainable shape design has been cast and subjected to compressive strength to obtain the strength performance of the proposed LRGP mortar. At optimal mixture, the SEM images exhibited improvement in the interfacial transition zone (ITZ) among WRA and binder, leading rubberized geopolymer with 15% WRA to achieve a strength of 27.47 MPa after 28 days and with a reduction in density by 7.2%. The findings of this study can provide valuable insights on utilizing WRA in the shape design and formulation of geopolymer mortar, a key ingredient in the development of functional environmentally friendly building materials.

Effect of various geopolymerization parameters on poor quality Afşin-Elbistan fly ash-based geopolymer concretes with ground granulated blast furnace slag

AbstractThe utilization of Afşin-Elbistan fly ash (FA), which cannot be used in cement and concrete industry in production of geopolymers, has been studied with some preliminary trials. In this study, FA of Afşin-Elbistan thermal power plant, which does not fit any of FA classes according to ASTM C 618, was used as a geopolymer binder raw material. The main motivation of the study is to investigate the partial usability of this type of FA, which is not sufficient on its own and creates a large amount of waste, as a geopolymer raw material. FA was replaced with ground granulated blast furnace slag (GGBFS) by the ratios of 25% and 50% (by weights) in order to develop the properties of geopolymer concrete. Sodium silicate (SS) and sodium hydroxide (SH) (10 and 14 M) were used as activators. Three different activator to binder ratios (0.45, 0.55 and 0.65) and three SS/SH ratios (0.75, 1.0 and 1.5) were chosen. Unit weight, compressive strength, splitting tensile strength, and ultrasonic pulse velocity tests were performed for 28 and 60 days. In order to investigate the microstructure, scanning electron microscopy (SEM) analyses were performed. As a result, GGBFS incorporation enhanced the properties of Afşin-Elbistan FA-based geopolymer concrete. With the increase of GGBFS content, the compressive strength values increased. The highest strengths were obtained from 50% GGBFS groups. The results revealed that Afşin-Elbistan FA (AEFA), which has the highest waste reserve among the thermal power plant fly ashes in Turkey, could be evaluated as partial geopolymer raw material. Graphical abstract

Exploring the potential of fly ash cenosphere—capric acid composite phase change material in concrete incorporating supplementary cementitious material

AbstractIncreasing demand for energy globally, with the building sector being a significant contributor to energy consumption, is a major issue. To address this, efforts are being made to make buildings more energy efficient, including lowering the demand for heating, ventilation, and air conditioning to decrease energy demand. Phase change material (PCM) functions as a latent heat energy storage material that absorbs heat energy while transforming its phase from solid to liquid and then releases the heat energy when it transforms from liquid to solid state. Integrating PCM into building materials can considerably enhance their energy storage density. In this study, the potential of using fly ash cenosphere—capric acid (CeCA) composite PCM in concrete is evaluated. The mechanical, durability and thermal properties of the CeCA blended concrete were investigated. Furthermore, the CeCA‐concrete is enhanced with auxiliary cementitious substance, namely ground granulated blast furnace slag (GGBS). The optimal proportion of CeCA was determined to ensure a balance of compressive strength and thermal conductivity. The results indicated that the compressive strength of the CeCA blended concrete lowered with an increase in the percentage of CeCA. The thermal conductivity of the concrete specimen was lowered by 33.14% at a 25% incorporation of CeCA, resulting in improved thermal performance. The incorporation of GGBS has enhanced the mechanical and durability performance of CeCA‐Concrete. The optimal concrete specimen was found to be 25% CeCA +40% GGBS, which had greater thermal efficiency than the control specimen with similar strength performance. The findings were validated by field emission scanning electron microscopy analysis of the concrete specimen.

Geopolymer synthesis and performance paving the way for greener building material: A comprehensive study

Ordinary Portland Cement (OPC) is renowned for its robustness and endurance in construction, but its manufacturing process incurs substantial energy consumption and leads to significant carbon dioxide emissions. Geopolymers (GP), conversely, represent a synthetic material derived from industrial by-products like calcined materials and slag. This study employs a diverse array of techniques to optimize the formulation of geopolymers and to evaluate their initial state (slump, reactivity) and mechanical characteristics (mechanical strength, density). Materials used are a combination of metakaolin (MK), granulated blast furnace slag (GBFS), and potassium silicate (K2SiO3) as an alkaline reagent (AR). The findings indicate that geopolymers exhibit strength akin to that of Portland cement (even better at early ages, between +16% to +88% higher), thereby positioning it as a credible substitute. The examination of the microstructure through methods such as nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Thermogravimetric analysis (TGA) reveals that the synthesized material possesses a stable interconnected polymeric 3D-structure. Furthermore, mercury porosity analysis demonstrates the presence of finer pores (nanometric) consistent with a densely packed and closely-knit micelle structure. This study demonstrates that geopolymers blend comprising calcined earth, metakaolin, and slag holds promise as a viable alternative to OPC.

Compressive Strength, Permeability, and Abrasion Resistance of Pervious Concrete Incorporating Recycled Aggregate

Extensive use of cement in the construction industry increases CO2 emissions and has a negative impact on the environment. In this work, recycled coarse aggregate (RCA) from construction and demolition wastes (C&DW) was used to fabricate sustainable pervious concrete (PC). In order to mitigate the environmental hazards of excess cement waste and to improve the engineering properties of PC, silica fume (SF) and ground granulated blast-furnace slag (GGBS) were added. The effects of SF and GGBS on the compressive strength, permeability coefficient, porosity, and abrasion resistance of recycled aggregate pervious concrete (RAPC) were investigated. The results show that the incorporation of GGBS and SF effectively improves the compressive strength of RAPC but reduces the permeability coefficient and porosity. Moreover, due to the filling effect and pozzolanic activity, the incorporation of GGBS and SF significantly enhances the abrasion resistance of RAPC. Furthermore, the relationships between the compressive strength, permeability coefficient, porosity, and abrasion resistance of RAPC are clarified. The optimum replacement is achieved when the SF content is 7%, and the GGBS content is 20%, respectively, which results in the highest compressive strength (28.9 MPa) and the lowest permeability coefficient (1.2 mm/s) at 28 days, and the lowest mass loss rate (12.1%) after the Cantabro abrasion test.

Mechanical behavior and microstructure evolution of slag-fly ash based geopolymer stabilized sand

Geopolymers made from ground granulated blast-furnace slag and fly ash could effectively address the issues of high energy consumption and emissions associated with Portland cement, which is commonly used as a soil curing agent. In this study, the unconfined compressive strength and microstructure of geopolymer-solidified sand were presented and analyzed. The study focused on effect of the type and ratio of activator, the ratio of slag to fly ash, and the ratio of water to (activator and cementitious materials) (W/(A + C)) on the behavior of geopolymer stabilized sand. The results of computed tomography (CT), and scanning electron microscope (SEM) indicate that the variation in initial water content significantly affects the porosity of the specimen, which increased as initial water content increased. The cracks were mainly found at the joints between the individual aggregates and at the edges of the individual aggregates. The pore size distribution of the specimens was concentrated in the range 0.0761–5 μm, while the polymer particle distribution was concentrated in the range 0.0761–10 μm, with a concentration of over 90 %. A significant amount of cementing material was densely distributed around both the aggregates and the pores. CT and SEM testing techniques enable a thorough analysis and mutual verification of the self-compacting process, pore distribution, and size, as well as the distribution of cementing material within the specimens. The optimum ratio for B-S19 has been determined.

Role of supplementary cementiteous materials in mitigating heat of hydration in mass concrete elements

Concrete’s heat of hydration can cause wide restraint cracks, delayed ettringite formation and low strength. The heat of hydration in concrete poses significant challenges in the construction industry particularly in mass concrete elements. Addressing these challenges, the utilization of supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GBFS) in concrete has been extensively studied for their individual contributions in modifying the heat of hydration. However, the comparative effectiveness of FA and GBFS, as well as the implications of their combined use in a ternary blend mix, remain underexplored. This study aims to bridge this gap by investigating the heat evolution profiles of concrete blends incorporating varying proportions of FA, GBFS, and general Portland cement (GPC). Through a series of semi-adiabatic tests, the study evaluates the hydration kinetics, maximum temperature rise, and time delay to peak temperature for binary and ternary mixes. The findings suggest that while individual SCMs like FA and GBFS offer distinct thermal benefits, their combined use in a ternary blend presents a synergistic effect, optimizing heat management in concrete. In essence, this study not only underlines the potential of ternary blends in enhancing concrete's thermal performance but also emphasizes their role in promoting sustainable and resilient construction practices.

Why sustainable concrete cannot penetrate concrete markets

Several studies have shown that sustainable concrete mixtures could be a solution to reduce the CO2 emissions of concrete while utilizing supplementary cementitious materials (SCMs) that are waste byproducts, including fly ash, metakaolin, and ground granulated blast furnace slag. However, for these sustainable concrete mixtures to be adopted as a replacement for conventional ordinary Portland cement concrete (OPCC), site engineers, decision-makers, and authorities need to be aware of the mechanical and durability properties of these sustainable concrete mixtures. A brief review of the mechanical and durability properties of both geopolymer concrete and alkali-activated cement demonstrates the objective performance relative to OPCC. Then, the results of a survey targeting researchers, site civil engineers, decision-makers, and employees in governmental agencies are presented. The results indicate that even though the mechanical and durability properties of geopolymer/sustainable concrete are recognized, limited awareness and availability present significant challenges to the adoption of sustainability concrete in infrastructure projects. The survey highlights the need for focused marketing efforts to educate decision-makers on the availability as well as mechanical and durability properties of geopolymer concrete. Additionally, it serves as a call for future research to overcome obstacles such as high initial cost, safety concerns, and limited practical applications.

Freeze-thaw Resistance of Concrete using Ground Granulated Blast-furnace Slag and Blast-furnace Slag Sand in Salt Water

Freeze-thaw Resistance of Concrete using Ground Granulated Blast-furnace Slag and Blast-furnace Slag Sand in Salt Water

Optimizing compressive strength of quaternary-blended cement concrete through ensemble-instance-based machine learning

Optimizing the composition of concrete, particularly when incorporating ordinary Portland cement (OPC) along with supplementary materials such as ground granulated blast furnace slag (BF), fly ash (FA), and silica fume (SF), poses challenges due to the intricate nonlinearity inherent in concrete properties. Addressing this challenge has urged growing interest in employing Machine Learning (ML) techniques for precise property assessment. In this investigation, various predictive models, encompassing eXtra Gradient Boosting (XGB), random forests (RF), and K-Nearest Neighbor (KNN) algorithms were formulated to predict the compressive strength (CS) of ternary-blended concrete incorporating OPC, BF, FA, and SF. Through comprehensive analysis of an extensive dataset comprising 810 distinct records, the study identifies optimal concrete blends, providing invaluable insights for practical applications. Evaluation of ML models underscores the superior performance of XGB, with a coefficient of multiple determination (R2) values of 0.923 and 0.997 for training and testing datasets, respectively, indicative of exceptional predictive accuracy. Additionally, SHAP values underscore the importance of input age, water–binder ratio, and OPC content. This research enhances understanding of ternary-blended concrete characteristics, offering practical implications for construction practices and laying a foundation for future research endeavors to refine ML models, explore attribute interactions, and optimize concrete constituent proportions for broader civil engineering applications.

From cement to geopolymers: Performances and sustainability advantages of ambient curing

The production of Portland cement results in substantial carbon emissions. Geopolymers are regarded as highly promising alternative binder materials to cement due to their low energy consumption and excellent mechanical properties. However, it should be noted that the thermal curing process of geopolymers diminishes their low-carbon advantage. In this study, ground granulated blast furnace slag (GGBS) was used to replace metakaolin (MK) by the ratio of 10 %, 20 %, 30 %, 40 %, and 50 % to produce geopolymers. The aim was to examine the impact of GGBS content on the thermal curing performance of MK-based geopolymers. The microstructure of the specimens was analyzed using SEM and XRD analysis techniques. Lastly, a comprehensive assessment of their sustainability potential was carried out. As a result, slag may increase flow spread, decrease the setting time, and effectively improve the mechanical properties which curing on ambient temperature. The group with 50 % slag content had the highest compressive and flexural strengths, reaching 55.9 MPa and 8.45 MPa at 28 d, respectively. The drying shrinkage of geopolymers increases as the GGBS content goes up. Notably, owing to the evolution of chemical transformation and gel structure, MK exhibits a significant mitigation on shrinkage. Ultimately, with a 50 % slag content, the carbon dioxide emissions of geopolymer can be reduced to 265.36 kg CO2-eq, which is a 43.6 % decrease compared to that of OPC. With a comprehensive consideration of the performance and sustainability potential of geopolymers, it is recommended to introduce GGBS content in the range of 30 %–40 %.

Analyzing the Effect of Gypseous Soil Stabilized with Ground Granulated Blast Furnace Slag by DBN-MFO

Analyzing the Effect of Gypseous Soil Stabilized with Ground Granulated Blast Furnace Slag by DBN-MFO

Effects of carbonation and sponge wetting solution on diffusion potential of carbonated concrete with supplementary cementitious materials

Potential measurement of reinforced concrete is critical for identifying the corrosion state of rebar and monitoring the pH value and chloride concentration of concrete pore solution but remains a challenging task due to the many uncertainties involved. This study aims to investigate the effects of concrete carbonation and the sponge wetting solution on the diffusion potential of partially carbonated concrete blended with supplementary cementitious materials (SCMs). Portland cement is replaced by silica fume (SF), pulverized fly ash (PFA) and ground granulated blast-furnace slag (GGBS) at different replacement levels. Other experimental variables include the degree of concrete carbonation, the wetting solution of the sponge (tap water and 0.3 M NaOH) and the degree of saturation. The results indicate that concrete carbonation-induced diffusion potential would lead to significant errors on the monitoring of the pH value and chloride concentration by measuring the potential between the embedded sensors and external reference electrode. During the pH value and chloride concentration monitoring, 0.3 M NaOH should be used as the wetting solution of sponge for non-carbonated concrete and partially carbonated concrete while tap water should be used for fully carbonated concrete. To some extent, the decline in the degree of concrete saturation can reduce the diffusion potential.

The rutting performance of cold bitumen emulsion mix using ground granulated blast furnace slag and lime as fillers

Abstract Rutting is a worldwide recognized distress in bituminous pavement caused by repetitive passage of traffic loads at high temperature. High air voids and poor early strength of cold bitumen emulsion mix (CBEM) can cause rutting deformation even at lower temperatures, making it undesirable to practitioners. The CBEM can be effectively modified by using hydraulic materials as filler. The present study examines the effect of ground granulated blast furnace slag (GGBFS) and lime as fillers on rutting characteristics of CBEM at varying temperatures (i.e., 40, 50, 60oC). The conventional stone dust (SD) filler was partially replaced by GGBFS. For further modification, lime was added in CBEM containing GGBFS. Initially mix were selected for rutting test based on the results obtained by Marshall stability, indirect tensile strength, retained Marshall stability, and tensile strength ratio tests. Based on these results, 80% of GGBFS was optimized for CBEM production. Incorporating 20% lime with 80% GGBFS in CBEM further improved the properties mentioned above. Both mixes were selected for the rutting test, along with CBEM containing 100% SD and CBEM containing 20% lime, which were also selected for comparison purposes. Wheel tracking device was used for rutting test on CBEM at varying temperatures. Based on results, it was found that increasing testing temperature increases the rutting deformation. However, the CBEM containing GGBFS and lime by 80% and 20% of total weight of filler in the mix, respectively, gave better rutting resistance at each testing temperature and provide less temperature sensitivity. So, this paper introduces the blended GGBFS and lime as a new composition in CBEM that provides improved laboratory strength, moisture susceptibility resistance, and rutting resistance.