Granulated Blast Furnace Slag Research Articles

Sustainable soil stabilization using industrial waste ash: Enhancing expansive clay properties

This study investigates the use of various industrial waste materials—silica fume (SF), cement kiln dust (CKD), calcium carbide residue (CCR), rice husk ash (RHA), and ground granulated blast furnace slag (GGBS)—as eco-friendly stabilizers for expansive clay soil (ECS). Laboratory tests were conducted to assess the impact of different proportions (3 %, 6 %, and 9 %) of these additives on the soil's physical, mechanical, and microstructural properties. Results indicated that the inclusion of industrial waste significantly improved the soil's behavior, with notable reductions in liquid limit (up to 37.66 %), plasticity index (up to 74.76 %), and swell potential. Additionally, unconfined compressive strength (UCS) and shear strength increased substantially, with UCS values rising from 114.64 kPa to 1582.91 kPa at 30 days of curing for 9 % GGBS. Microstructural analyses confirmed the formation of cementitious compounds, which enhanced soil particle bonding and durability. These findings suggest that industrial waste materials can serve as effective and sustainable alternatives to traditional soil stabilizers, offering both performance improvements and environmental benefits.

Effect of glass powder on alkali-silica reaction mitigation for tunnel waste rock slag in concrete

Alkali-silica reaction (ASR) poses a critical damage to concrete structures, which will lead to a serious reduction for the service life of concrete. This study investigated the mitigation of ASR using glass powder (GP) through accelerated mortar bar tests (AMBT), with fly ash (FA) and ground granulated blast-furnace slag (GGBS) setting as control groups, and the replacement ratio of GP, FA and GGBS is 0, 5 %, 10 %, 20 %, 30 % and 40 % respectively. The results reveal that both FA and GGBS can mitigate the possibility of ASR: GGBS can significantly mitigate ASR only when its content reaches up to 40 % and FA effectively suppressed ASR with a dosage of 20 %. For the GP, particles larger than 75 μm will increase the risk of ASR, and as evidenced by the clear presence of ASR-gel and cracks in the mortar bars observed. Conversely, GP with particle sizes smaller than 75 μm effectively mitigated ASR, achieving significant suppression at a content of 20 %. The possible mitigation mechanism of GP could be attributed to the pozzolanic reaction between the GP and the alkali in the concrete, which reduces the alkali in the cement. This work might offer some reference to ASR risk control in concrete.

Performance evaluation of high early strength micro-expansion geopolymer grout potentially used for sustainable road infrastructure

This study aimed to develop a high early strength micro-expansion geopolymer grout material derived from recycled concrete and ground granulated blast-furnace slag (GGBS), which can be used to fill the subgrade voids and strengthen weak subgrade. A series of grout materials with varying proportions of recycled concrete were prepared, and their setting time, flowability, and strength characteristics were evaluated. The results indicated that the grout material containing 50 % recycled concrete had a final setting time of 29 min, a flow time of 15.2 s, and a 7-day compressive strength of 40.6 MPa, all of which met the requirements for subgrade grout materials. To further enhance the performance of the grout, the additives including 2 % calcium chloride (CaCl2), 5 % magnesium oxide (MgO), and 5 % united expansive agent (UEA) were used. Results showed that the samples containing 50 % recycled concrete and 2 % CaCl2 exhibited a 26.5 % increase in strength after 100 min of curing, while MgO and UEA reduced shrinkage by 112.5 % and 90.0 %, respectively. Additionally, microstructural analysis using SEM and XRD provided valuable insights into the complex interactions between components and their effects on material integrity. The results demonstrated that the use of CaCl2 accelerated the hydration reaction, enhancing early strength, while the expansion agents MgO and UEA mitigated shrinkage and achieved micro-expansion at low concrete content. This study addresses environmental concerns by incorporating recycled materials, positioning the developed geopolymer grout as a sustainable, high-performance alternative in road construction. Integrating waste-derived components and innovative additives represents a significant step towards advancing sustainable practices in infrastructure development.

THE IMPACT OF INTERNAL HYDROPHOBIZATION ON THE PROPERTIES OF THE CEMENT-BASED MATERIALS WITH MINERAL ADDITIVES

The paper presents results regarding the possibility and effectiveness of carrying out the internal hydrophobization in cementbased materials with mineral additives such as granulated blast furnace slag, silica dust and silica fly ash. The obtained results indicate that effective internal hydrophobization by using triethoxyoctylsilane is achievable and provides protection against water by decreasing the capillary absorption of water in the material. However, it also affects the hydration process of the binder, which results in a reduction in the compressive strength of the material.

Ultrafine GGBS and Fly Ash as Cement Replacement for Sustainable Concrete

The construction industry is one of the major contributors to environmental degradation. Hence, it requires eco-friendly practices to make concrete more sustainable. This can be achieved by addition of mineral admixtures as a cement replacement. This process helps the environment in two ways: by reducing the carbon dioxide emission through cement replacement and by utilizing mineral admixtures such as fly ash, Ground Granulated Blast Furnace Slag (GGBS), metakaolin, rice husk ash and silica fume, which are all industrial wastes or by-products. Hence, this approach lowers the greenhouse effect and global warming by reducing carbon dioxide emissions and prevents environmental contamination by utilizing industrial wastes. This experimental study aims to find the perfect combination of mineral admixtures such as fly ash and ultrafine GGBS to maximize cement replacement in concrete without compromising its mechanical properties and achieving a more sustainable concrete for day-to-day practice. For this study, the fly ash percentage was maintained at 20% for all trials, with the ultrafine GGBS percentage varying from 15% to 30%. Keywords: Sustainable Concrete; Ultrafine GGBS; Fly ash; Mineral Admixture.

An Experimental Investigation on Nano-Enhanced Tertiary Blended Concrete Incorporating Industrial Wastes

Concrete is a crucial material in the construction industry; however, its production process releases carbon dioxide into the atmosphere. Undoubtedly, the building sector's increasing global interest unveils a challenge to its ability to withstand cement alternatives and manage the resulting outflows. Fly ash, GGBS (ground granulated blast furnace slag), Zeolite, rice husk, silica fume, metakaolin, and various industry by-products can typically replace cement. This research study aims to replace cement with multiple cementitious materials, individually and in combination, to evaluate the strength characteristics of blended concrete. The replacement percentages ranged from 0 to 30% for each substitute material, such as fly ash, GGBS, and Zeolite, and strength tests were done to assess the performance of the modified concrete after 7 and 28 days of water curing. Ordinary Portland Cement (OPC) is used to create M30 and M50 grades of concrete. Similarly, cement was replaced with fly ash, GGBS, and Zeolite in amounts ranging from 10 to 30% for M30 and M50 grades, and their strength was evaluated after 7 and 28 days of curing. The most efficient percentage of substitution for both the concrete grades is determined, and the corresponding replacement ratio is used to produce the blended concrete, which incorporates cement, fly ash, GGBS, and Zeolite. The overall findings reveal that the composite concrete, comprising four binding materials, demonstrated superior strength for the concrete grade compared to alternative substitutes. The optimal mixture ratios for M30 concrete after 28 days consist of 20% fly ash, 20% GGBS, and 10% zeolite. Moreover, different ratios of Zeolite-10%, Fly-Ash-30%, and GGBS-20% were used to produce M50 concrete.

The influence of the mole modulus of the activator SiO2/Na2O on the formation of properties of geopolymer

The objective of the study was to determine the suitability of fly ash derived from the combustion of hard coal in a heat and power plant located in Lodz to produce geopolymer. The study investigated the effect of the molar modulus of the activator (SiO2/Na2O) on the compressive strength over time in mortars modified with the addition of granulated blast furnace slag (0, 10 and 50%). An important aspect of the analyses is the possibility of managing locally occurring products from industrial processes

Experimental Investigation of the Durability of Ambient-Cured Metakaolin-Based Geopolymer Concrete in Different Sustainable Environmental Conditions

Geopolymer concrete (GPC) has received much attention among researchers in recent decades due to its increased durability properties. It helps reduce massive pollution and high energy consumption during cement production. Various cementitious materials having high alumino-silicate, such as, fly ash (FA), ground granulated blast furnace slag (GGBS), rice husk ash (RHA), and metakaolin (MK), are typically used for producing GPC. These materials are activated by an alkaline solution through a polymerization process. This study examined the durability properties of metakaolin-based GPC with fly ash and GGBS under ambient curing conditions (23 ± 20 ℃). The mechanical characteristics like compressive strength, splitting tensile strength, flexural strength, and durability properties like the sorptivity volume of permeable voids exposed to chloride, sulphate, and acid environments were studied and reported. Also, an effort has been made to establish a relationship among the mechanical properties. The test results show that better performance of GPC can be achieved with 40% replacement of MK with 10% FA and 50% GGBS under ambient curing than controlled concrete. The MK-GPC with a higher proportion of metakaolin, showed good resistance to environmental factors. It is a potential alternative to conventional cement concrete.

Studies on the performance of alkali-activated aluminosilicate geopolymer mortar against exposure to acid, sulfate, and elevated temperature

An alkali-activated aluminosilicate is a group of materials that have the potential to reduce the carbon footprint of the construction industry. Several combinations of materials have been explored for producing alkali-activated aluminosilicate geopolymer mortars, emphasizing the need to understand their resistance to chemical attack and elevated temperatures to ensure long-term durability. The present study prepared fly ash-based alkali-activated aluminosilicate mortar using fly ash (FA) and ground granulated blast furnace slag (GGBS) without heat curing. Properties such as compressive strength and weight loss were evaluated after chemical attack and exposure to high temperatures (200° to 1000°), and compared with PC mortars. The result shows that fly ash and GGBS-based alkali-activated aluminosilicate mortar (AAAM) exhibit better resistance to chemical attack and high temperatures than conventional mortar. Specifically, after 180 days of acid exposure, PCM showed a mass loss of 5.06% and compressive strength loss of 85%, while AAAM had a mass loss of 2.88% and compressive strength loss of 71%. Sulfate exposure led to a mass gain of 55.77% for PCM and 27.35% for AAAM, with compressive strength losses of 55.77% for PCM and 27.35% for AAAM. Elevated temperatures (1000°) resulted in a compressive strength loss of 68% for PCM and 45% for AAAM. To substantiate these results, X-ray diffraction (XRD) and Fourier Transformation Infrared Spectroscopy (FTIR) were used to study the changes in the bonding behavior of C-A-S-H (Calcium-Aluminate-Silicate-Hydrate) and N-A-S-H (Sodium-Aluminate-Silicate-Hydrate) when exposed to chemical attack and elevated temperatures.

Balancing Sustainability and Strength: Analyzing the Effects of Textile, Tannery, and Water Treatment Sludge on Brick Performance

This study investigates the feasibility of incorporating various industrial waste materials, specifically textile sludge, tannery sludge, and water treatment plant sludge, in brick production as a sustainable construction practice. The research analyses the impact of varying sludge proportions on the compressive strength of fired clay bricks. Results indicate an inverse relationship between increasing sludge content and compressive strength across all types. Bricks incorporating higher proportions of textile sludge exhibited a linear decrease in compressive strength, ranging from 0.1 MPa to a low of 0.005 MPa. Similarly, increasing the ratio of tannery sludge to fly ash Class C and Ground Granulated Blast-furnace Slag within the brick mixture consistently corresponded with reduced compressive strength, with a 5:70:25 mix yielding 0.8 MPa and a 40:30:30 proportion resulting in 0.17 MPa. Water treatment plant sludge exhibited a similar trend. A mix proportion of 5:70:25 (sludge: fly ash class C: GGBS) yielded a compressive strength of 1.87 MPa while increasing the sludge proportion to 40:50:10 resulted in a lower compressive strength of 1.20 MPa. These findings underscore the importance of a balanced approach when incorporating industrial sledges in brick production. While beneficial from a sustainability perspective, the observed reduction in compressive strength, particularly compared to conventional clay bricks exceeding 2.5 MPa, necessitates careful consideration. Future research should focus on optimizing mix designs, incorporating performance-enhancing additives, or identifying applications where lower compressive strengths are acceptable to fully realize the potential of these waste materials in sustainable construction.

Stabilized/solidified chlorine saline soils with ground granulated blast furnace slag and calcium carbide residue

To optimize the use of chlorine saline soils commonly found in many coastal areas, ground granulated blast furnace slag (GGBS) and calcium carbide residue (CCR) were used in this study to stabilize/solidify these soils. This study aims at evaluating the suitability of GGBS-CCR as industrial by-products in improving the mechanical behaviors of chlorine saline soil in comparison with the use of Portland cement (PC) as a traditional binder. The optimal proportion of the binder was determined by the unconfined compressive strength, conductivity, and leaching characteristics. Moreover, the water stability coefficients, collapse coefficients and microscopic characteristics of the solidified soil were evaluated. The results reveal that when the ratio of GGBS to CCR in the binder is 4:1, the 28-day unconfined compressive strength reaches 4.53 MPa, and the leaching of chloride ions is reduced by 94.1 %. The excellent water stability and reduced collapsibility further indicate that GGBS-CCR is a preferable binder for solidifying saline soil compared to PC. Furthermore, microscopic analysis revealed that chloride ions in the saline soil were involved in the hydration reaction to form Friedel's salt.

Study on the working performance and microscopic mechanism of high-performance grouting material (HPGM) reinforced dense fine sand layer

To address the challenges of small diffusion radius, low early strength and long setting time of traditional cement grout in dense fine sand layer, based on the synergistic mechanism, a novel high-performance grouting material (HPGM) was developed using ground granulated blast-furnace slag (GGBS), ultra-fine fly ash (UFFA), and ultra-fine Portland cement (UFPC) as raw materials. Firstly, Laboratory experiments were conducted to investigate the working performance of HPGM under varying proportions. Secondly, based on the self-designed advanced small pipe grouting full-scale test device, the diffusion performance and reinforcement characteristics of HPGM under varying proportions were analyzed. Finally, the XRD and SEM testing methods were employed to elucidated the hydration mechanism of the HPGM. The test results indicate that as the mass ratio of GGBS to UFFA decreases, there is a gradual increase in hardening rate, fluidity and setting time of HPGM. Additionally, the unconfined compressive strength (UCS) initially increase before decreasing. Furthermore, with the decreased mass ratio of GGBS to UFFA, the HPGM diffused in dense fine sand layer through compaction-splitting, permeation-splitting, and splitting grouting processes. The hydration products of the HPGM primarily consist of C(-A)-S-H, AFt, and Ca(OH)2, when the mass ratio of GGBS to UFFA falls within the range of 4:2–3:3, the UFFA facilitates the AFt hydration products in significant quantities. Its cementation and filling effect lead to the formation of a dense microstructure in the soil, resulting in a substantial reduction in permeability coefficient and a marked increase in UCS. The research findings can offer high-performance grouting material for underground engineering construction while also presenting innovative ideas for resource utilization from solid wastes like GGBS and UFFA.

Carbonation resistance of fly ash/slag based engineering geopolymer composites

Engineering geopolymer composites (EGC) are promising environmentally friendly building materials with excellent mechanical properties. However, the durability of EGC is compromised by gradual carbonation from atmospheric exposure. For the first time, this study provided an insight of the carbonation of EGC by comprehensively investigating the effect of mix design, such as fly ash/ground granulated blast furnace slag ratio (FA/GGBS ratio), alkali content, water/binder ratio (W/B ratio) and polyethylene (PE) fibre content, on its carbonation resistance. Our results showed the components in EGC affected the carbonation through the alternation of microstructures. An increase of FA content and W/B ratio significantly increased the carbonation depth by 206.6 % and 116.3 % respectively due to the increased porosity and transition pore fraction, resulting in more than 30 % reduction in tensile strength and 15 % reduction in compressive strength. However, increased alkali and fibre content prevent carbonation with around 60 % and 26 % decrease of the carbonation depth, leading to a less loss of the mechanical properties. Furthermore, we tested the pH values of the EGC along the carbonation depth, proposing a novel approach to assess the carbonation degree by dividing the area into completely carbonated area (pH around 9.21–10.44) and non-carbonated area (pH around 12.58–13.37). These findings provide insights for mitigating carbonation effects in EGC and facilitate the widespread use of this sustainable material in construction applications, ensuring long-term durability and reliability.

Stabilization strategies for granite waste powder applied in sustainable pavement subgrade: Mechanical and durability performance

The sustainable and efficient treatment of massive granite waste powder (GWP) has received increasing attention. This study proposes a novel method for recycling GWP cemented by inorganic binder-stabilized materials (IBSM) for sustainable pavement subgrade filler, i.e., IBSM-stabilized GWP (ISG). IBSM consists of Portland cement (PC), quicklime (QL), ground granulated blast furnace slag (GGBS), and sodium dodecyl benzene sulfonate (SDBS). Response surface methodology (RSM) and microstructure analysis were employed to analyze the effects of IBSM components on ISG mechanical properties and durability. The 56d compressive strength of ISG is above 2.62 MPa, meeting the minimum criterion of 1 MPa. The residual strength coefficient after 5 freezing-drawing cycles is generally greater than 65 %, except for the groups with high QL content. Both PC and GGBS are positively correlated with the performance of ISG. Moreover, multi-objective optimization identifies the optimal mix ratio: 3.03 % PC, 0.83 % QL, 3.47 % GGBS, and 0.18 % SDBS. The optimal ISG presents excellent strength and durability performance, with S7d of 1.61 MPa, S56d of 3.88 MPa, Sw of 3.35 MPa, Rftc of 90 %, Rwdc of 92.01 %. These findings provide insight into the stabilization strategies of GWP using in highway subgrade filler, which can alleviate the environmental pollution induced by GWP waste.

An investigation of rheological properties and sustainability of various 3D printing concrete mixtures with alternative binders and rheological modifiers

This study assessed the performance of eco-friendly 3D printable mixtures prepared with various wastes such as fly ash (FA), granulated blast furnace slag, and marble dust. Additionally, the study investigated the impact of a viscosity-modifying agent (VMA) and silica fume (SF) on the mixtures’ rheological and mechanical characteristics. The influence of different wastes and VMAs on the fresh and hardened properties of printable mixes was investigated. Besides, the extrudability and buildability properties of the mixtures were evaluated with a manual extrusion device. The sustainability assessment was conducted using embodied CO2 and embodied energy index, integrating both the mixtures’ environmental implications and engineering characteristics. Experimental outcomes indicated that the inclusion of SF led to enhancements in the fresh properties of the 3D printable mixes. The VMA mixes exhibited significantly higher static yield strength than mixes incorporating SF. Considering printability and sustainability, the FA-SF mixture was identified as the optimal one.

Mechanical Properties and Chloride Penetration Resistance of Concrete Combined with Ground Granulate Blast Furnace Slag and Macro Synthetic Fiber

Concrete with good mechanical properties and durability has always been a necessity in engineering. The addition of fibers and supplementary cementitious materials to concrete can enhance its mechanical and durability performance through a series of chemical and physical interactions. This study aims to investigate the effects of key parameters on the compressive strength, splitting tensile strength, and chloride penetration resistance of concrete combined with ground granulate blast furnace slag (GGBS) and macro polypropylene synthetic fiber (MSF). Based on the Taguchi method, a total of eighteen mixtures were evaluated, considering the effects of GGBS content, MSF content, water-to-binder (w/b) ratio, and chloride solution concentration on concrete properties. The results showed that the w/b ratio has a significant impact on the properties of concrete, which are enhanced by a decrease in w/b ratio. The GGBS content had little effect on the 28-day strength of concrete, which even decreased with a large GGBS content, but GGBS had a positive effect on the long-term strength of concrete. Moreover, the chloride penetration resistance of concrete was enhanced by an increase in the GGBS content. The MSF content had no obvious effects on the compressive strength and chloride penetration resistance of concrete, but it could enhance the splitting tensile strength to some extent, and this enhancement was more obvious over time. The chloride diffusion coefficient of concrete changed with the concentration of chloride solution, and the two increased simultaneously.

Optimization and characterization of GGBFS-FA based alkali-activated CLSM containing Shield-discharged soil using Box-Behnken response surface design method

With the rapid growth of shield-discharged soil (SDS), there is an increasing demand for effective recycling and transformation methods. This study aims to develop an alkali-activated controlled low-strength material (CLSM) by utilizing ground granulated blast furnace slag (GGBFS) and fly ash (FA) as precursors, SDS as fine aggregate, and sodium hydroxide (NaOH) solution as an activator. The Box-Behnken design (BBD) within the response surface methodology (RSM) framework was employed, considering liquid-to-solid ratio, alkali equivalent, aggregate-to-binder ratio, and foam agent content (FC) in SDS as key factors. Regression models were constructed to analyze the effects of these factors on flowability, bleeding rate, setting time, compressive strength, elastic modulus, and water absorption. The results confirmed the effectiveness of RSM in determining optimal conditions for material performance. In addition, microscopic analyses were conducted to explore hydration products, microstructural characteristics, and pore distribution. The findings revealed that the fresh density of the CLSM ranged from 1460 to 1740 kg/m³, classifying it as a low-density material. The 28-day compressive strength varied from 1.837 to 7.884 MPa, while the setting time ranged between 1.2 and 5.6 hours. These properties comply with the ACI 229 standard and are suitable for practical applications. Interestingly, when the aggregate-to-binder (A/B) ratio was between 0.2 and 0.4, increasing the ratio did not lead to a consistent reduction in mechanical properties. Instead, the properties initially decreased and then improved. Moreover, an increase in foam agent content (FC) extended the setting time and reduced mechanical strength. The correlation coefficients of all models exceeded 0.98, with a coefficient of variation below 10 % and a signal-to-noise ratio greater than 4, demonstrating strong reliability and accuracy of the models. Additionally, the average relative error between predicted and experimental values in six scenarios was under 6 %, validating the feasibility of optimizing the design of alkali-activated CLSM using RSM. The formation of Ca(OH)₂ crystals facilitates early strength development, resulting in final cementitious materials reticular, fibrous C-S-H, C-A-H, and other gel-like hydration products. Calcium promotes the formation of gels such as C-S-H, shortening the setting time and enhancing microstructural density. This study provides valuable insights for optimizing the design of alkali-activated CLSM containing SDS, thereby expanding methods for utilizing construction and demolition waste.

Recycling and optimum utilization of GFRP waste into low-carbon geopolymer paste for sustainable development

To provide an eco-friendlier alternative to traditional ordinary Portland cement (OPC) binder, this study utilized glass fiber reinforced polymer (GFRP) waste powder as a precursor material to prepare geopolymer paste (GP). Through a series of mechanical, thermal, and mineral admixture activation procedures, efforts are made to augment the reactivity of GFRP powder-based geopolymers. The research reveals that subjecting GFRP powder to a 30-min grinding process amplifies the compressive strength of GP by up to 37 %. Moreover, elevating curing temperatures to 60 °C leads to a substantial enhancement in the strength of GFRP powder-based GP, attributable to the formation of more amorphous N-A-S-H and C-(A)-S-H gels. However, prolonged grinding durations yield only marginal alterations in particle size, while curing at 80 °C demonstrates a detrimental effect on strength. The choice of resin exhibits a discernible impact on both workability and strength. Notably, pure glass fiber powder-based GP displays superior compressive strength but exhibits increased brittleness, whereas GFRP powder-based GP excels in flexural strength. Moreover, the inclusion of ground granulated blast furnace slag (GGBS) in the mixture accelerates setting time and reduces flowability of GFRP powder-based GP. Strength shows a positive correlation with GGBS content, although the impact on flexural strength is less pronounced compared to compressive strength. Life cycle assessment (LCA) showed GFRP powder-based GP with 50 % GGBS replacement had a 35 %–48 % lower Global Warming Potential (GWP)/strength ratio compared to OPC pastes. Furthermore, this formulation demonstrates a 15 % decrease relative to GGBS-based GP, and a reduction of 13 %–25 % compared to GGBS/Fly Ash (FA)-based GPs. These results underscore its potential as an environmentally preferable building material.

Crack-healing of cost-effective engineered cementitious composites reinforced by recycled selvage fiber

This paper presents the first experimental investigation of the crack-healing behavior of recycled selvage fiber-reinforced engineered cementitious composites (RSF-ECCs). Fly ash (FA), ground granulated blast-furnace slag (GGBS), and crumb rubber powder were utilized to fabricate greener ECCs. RSF was used as main reinforcement; it contains polyethylene (PE), glass (GS), and PET fibers. For overall mechanical properties, RSF-ECC incorporating GGBS (ECC-S-RSF) obtained a compressive strength of over 80 MPa and a tensile strain capacity of over 10%, values that are unprecedented in other recycled fiber-reinforced ECCs. Furthermore, the ECC-S-RSF showed the best cost efficiency among representative recycled and PE fiber-reinforced high-performance ECCs. In terms of the crack-healing performance, test results indicated that RSF-ECCs had excellent healing capacity in closing crack openings, and GGBS had a greater contribution to crack-healing than FA did. However, the stiffness and tensile restorations of RSF-ECCs were relatively modest compared to those of conventional ECCs. Calcium carbonate and C-S-H gel were dominant healing materials of RSF-ECCs.

Sulfate resistance of alkali-activated flyash-slag-lime concrete: comparative study of drying-wetting cycles and conventional exposure

Abstract Sulphate resistance of concrete is a crucial parameter for design of offshore structures. Of late alkali-activated materials are been given due consideration for infrastructure projects. In this context, the present study aims to assess the sulphate resistance of Alkali-Activated Concrete (AAC) with ternary blend of flyash-Ground Granulated Blast furnace Slag (GGBS) and limestone as the principal binder. The first phase of the study includes the optimization of ternary AAC mix with the inclusion of limestone as a potential binder to popularly used flyash slag blends. The inclusion of 5% limestone powder into the binder matrix is found to have beneficial effect on the mechanical properties of the ternary blended AAC. Further, an increase in the limestone powder content is not found to influence mechanical properties positively. The AAC mix with 5% limestone of total binder content was therefore selected for further evaluation of sulphate resistance. The sulfate resistance is evaluated under the alkaline media by subjecting AAC specimens to constant immersion and alternative drying and wetting cycles. The mechanical characteristics and mass reduction of the exposed samples were tested and compared with the conventional Ordinary Portland Cement (OPC) specimens. Evaluations were conducted over periods of 30, 45, 120, and 365 days of exposure. Scanning Electron Microscopy (SEM), and Energy Dispersion Spectroscopy (EDS) were also used to determine the surface morphology and mineral composition of samples after 365 days of exposure periods. The Flyash-Slag-Lime AAC exhibits denser morphology in comparison to OPC-based concrete, which in turn offers enhanced sulphate resistance.