ASTM C 1260によるフライアッシュ含有モルタルの安山岩に対するASR抑制効果の評価

Performance of sustainable concretes containing very high volume Class-F fly ash and ground granulated blast furnace slag

The present study investigates the potential of widely used supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GGBS) to improve the rheological and environmental performance of low-carbon cementitious pastes. Three binders consisting of 100% OPC, 25% FA, and 70% GGBS were tested at water-to-binder ratios of 0.4 and 0.45. The dynamic shear rheometer was employed to analyze shear-thickening behavior of various cementitious suspensions. Subsequently, the environmental life cycle assessment (LCA) was conducted within a “cradle-to-gate” framework, evaluating six environmental impact categories and proposing a novel approach to converting these impacts into a single environmental cost (USD). The results revealed that OPC suspensions exhibit the earliest and most pronounced shear-thickening onset, while 70% GGBS suspensions reduce global warming potential but increase acidification impact. In contrast, 25% FA suspensions minimize acidification impact. Moreover, the rheological behavior is significantly influenced by solid volume fraction (SVF) and particle morphology; 70% GGBS pastes demonstrate the highest yield stress (140 Pa) and plastic viscosity (1.61 Pa. s) at a w/b ratio of 0.4, attributed to their angular particle shape. The environmental cost of suspensions (100% OPC) is estimated at $13.92/m3, with OPC being the primary contributor. The findings highlight the potential of SCMs to enhance performance and reduce environmental impacts, supporting greater use of FA and GGBS for sustainable, low-carbon infrastructure development. Future research should focus on optimizing the combined use and dosage of FA and GGBS in low-carbon cementitious pastes to achieve a more effective balance among rheological performance, environmental sustainability, and economic viability. Equally important is the need to extend the assessment framework beyond the present scope by incorporating long-term performance and durability assessment, broader system boundaries, and more rigorous environmental cost evaluation should be incorporated to enable the development of robust and sustainable cementitious systems. Implication: India has set an ambitious goal of achieving carbon neutrality by 2070. In the coming years, a substantial increase in building construction is anticipated to accommodate the country’s growing population. However, this expansion threatens to hinder progress toward national sustainable development goals (SDGs) and commitments to the Paris Climate Agreement. Indian thermal power plants and steel plants produce substantial amounts of fly ash and slag, which are solid waste byproducts. To mitigate the environmental impact and reduce cement consumption, it is essential to utilize these materials in construction. By incorporating fly ash and slag as cement replacement materials, we can significantly decrease the carbon footprint of the construction industry, contributing to both sustainability and resource efficiency. The paper uniquely integrates the rheological properties of cementitious suspensions with a comprehensive environmental assessment, offering a dual perspective on performance and sustainability. A novel methodology has been proposed to consolidate environmental impacts into a single environmental cost, expressed in US dollars, providing a practical decision-making tool. We believe that this work integrating environmental assessment along with rheological properties is the first of its kind and will draw the attention of the international research fraternity working on the area of the rheology of cement-based materials and the life cycle assessment of construction materials. We believe that Journal of the Air & Waste Management Association is a highly suitable journal for this synthetic work as articles on these themes appear frequently in the journal. Being a journal with diverse readership base, I expect a huge interest from its audience for this study and a high citation impact post publication. I confirm that this article is original, unpublished, and not under consideration for publication elsewhere.

In order to improve the chloride ion penetration resistance of supplementary cementitious materials (SCMs) in blended cement, this study optimizes the particle size distribution of cementitious components based on the Fuller model. Portland cement (PC), fly ash (FA), and ground granulated blast furnace slag (GGBFS) are successfully divided into four particle size ranges by precision air classifier, which are 0–8, 8–30, 30–50, and 50–80 μm, respectively. The optimum cementitious materials in four ranges based on 28-day compressive strength are determined by nine groups of orthogonal tests. The blended cement with optimal performance is obtained by GGBFS in 0–8 μm, PC in 8–30 μm, GGBFS in 30–50 μm, and FA in 50–80 μm. The results show that the blended cement with SCMs based on Fuller model have superior microstructure and chloride ion penetration resistance, which is due to their smaller pore size, a strong volcanic ash effect, and chloride ion binding ability. In addition, this research presents a novel approach for realizing the application of a large amount of SCMs in blended cement.

Corrosion resistance coefficient of mortars incorporating different mineral admixtures were tested according to GB2420, and the expansion ratio of mortar bar immersed in 5% Na2SO4 solution was measured according to ASTM C1012. It is shown that all the mineral admixtures, including ground granulated blast furnace slag (SL) fly ash (FA), natural zeolite (NZ) and metakaolin (MK) were effective in decreasing the 15-week expansion and increasing the corrosion resistance coefficient of the specimens immersed in Na2SO4 solution as well.

This paper presents a study of the carbonation process of concrete with different initial curing periods consisting of fly ash and ground granulated blast furnace slag (GGBS). Both are exposed in a natural indoor environment for 720 days and at accelerated conditions. The relationship between compressive strength and carbonation depth is analysed. The factors affecting the carbonation of high-volume mineral admixture concrete in a natural environment and accelerated conditions are discussed using the orthogonal method. The factors include: water–binder ratio, content of mineral admixtures, total amount of cementitious materials and fly ash–slag ratio. The influence of different initial curing periods at early ages on carbonation depth is also reported. The results show that there is not always a linear rule between compressive strength and carbonation depth of high-volume mineral admixture concrete. Adequate curing at an early age can decrease the carbonation resistance of concrete significantly. For insufficiently cured concrete, the early stage before 56 days is the main developing stage of carbonation in a natural environment. An evident decrease of carbonation depth can be observed after exposure for 180 days and this will make the carbonated area turn to a red colour again when sprayed with phenolphthalein. In order to guarantee the excellent anti-carbonation ability of concrete in field structure, it is very important to ensure the initial curing time, except for restricting the water–binder ratio and the content of mineral admixtures.

When cement-based materials are transported at a construction site, they undergo high pressures during the pumping process. The rheological properties of the materials under such high pressures are unknown, and estimating the workability of the materials after pumping is a complex problem. Among various influential factors on the rheology of concrete, this study investigated the effect of mineral and chemical admixtures on the high-pressure rheology. A rheometer was fabricated that could measure the rheological properties while maintaining a high pressure to simulate the pumping process. The effects of superplasticizer, silica fume, nanoclay, fly ash, or ground granulated blast furnace slag were investigated when mixed with two control cement pastes. The water-to-cement ratios were 0.35 and 0.50.

Utilization of fly ash and ground granulated blast furnace slag as an alternative silica source in reactive powder concrete

Fly ash and ground granulated blast furnace slag (GGBFS) is a green construction material used to produce durable concrete. Experimental research on eco-concrete uses incorporating cement, fly ash and GGBFS. Fly ash and GGBFS replace different cement content by weighing, evaluating the workability, mechanical properties and durability of eco-concrete. The results also show that combining fly ash and GGBFS in concrete can create compressive strength concrete of 55MPa while the amount of cement used for 1m3 of co-concrete does not exceed 300 kilograms, the research also judges the water absorption, the chloride penetration resistance at 28 days with 30% replacement of GGBFS.

Improving the performance of a high belite clinker (HBC) by selecting appropriate blended materials is of great significance for its large-scale promotion and application. This research attempted to use dihydrate gypsum (DGP), fly ash (FA), and ground granulated blast furnace slag (GGBS) to prepare HBC + DGP (95% HBC + 5% DGP), HBC + FA (82% HBC + 3% DGP + 15% FA), and HBC + GGBS (82% HBC + 3% DGP + 15% GGBS) and explored the influence of different blended materials on various properties of HBC. In addition, the mechanism of the interaction between HBC and different blended materials in early and late stages was also revealed. The experimental results showed that GGBS had the most significant impact on HBC, mainly manifested in optimizing the particle distribution of HBC, increasing the standard consistency water demand of HBC, and shortening the setting time of the HBC paste. The improvement of the mechanical property of HBC by GGBS was its main advantage. Compared with HBC + DGP, the compressive strength of HBC + GGBS mortar increased by 113.9% and 43.5% at 7 and 28d, respectively. It was found that the addition of GGBS could increase the HBC second hydration exothermic peak to 15.4 mW/g. Further analysis proved that in the early stage, strong polarity OH- could dissociate the Ca-O and Si-O bonds on the glass phase of the GGBS surface, and the released Ca2+and SiO32- combined to form CH and C-S-H nanocrystalline nuclei, which could reduce the nucleation barrier of CH crystal and effectively promote C3S acceleration reaction. In the hydration later stage, the pozzolanic effect was utilized to generate more C-S-H, which could fill the pore of the cement matrix. This further enhanced the compressive strength of the HBC + GGBS mortar.

This study investigated the effects of partial cement replacement with Fly Ash (FA) and Ground Granulated Blast-furnace Slag (GGBS), as well as the addition of Polyvinyl Alcohol (PVA), on the mechanical and hardness properties of mortars. Mortar mixes were prepared with 15-30% FA (F-series), 15-30% GGBS (G-series), and varying PVA additions (P-series), and compared against a reference mix (Ref). Compressive, tensile, and flexural strengths at 28 days, along with Shore D hardness, were evaluated. Results indicated that both FA and GGBS improved 28-day compressive strength over the reference (Ref: 27.43 MPa), with optimal replacements at 20% FA (F20: 30.02 MPa) and 25% GGBS (G25: 34.12 MPa). GGBS mixes generally outperformed FA mixes across all tested properties, attributed to GGBS's higher calcium content promoting faster hydration and denser C-S-H gel formation. The addition of PVA further enhanced mechanical performance, with the P1 mix achieving the highest compressive (36.76 MPa), tensile (2.76 MPa), and flexural (5.43 MPa) strengths, likely due to PVA's film-forming and crack-bridging capabilities. However, excessive PVA addition showed diminishing returns. All modified mortars exhibited increased hardness compared to the reference, with GGBS (G30: 94.11) and PVA (P1: 93.73) mixes showing peak values. The findings highlight the effectiveness of GGBS as a supplementary cementitious material and demonstrate the significant potential of PVA modification for enhancing mortar strength characteristics, although optimal dosages are crucial.

Establishing the carbonation profile is of great significance to the prediction of the service life of reinforced concrete structures. In our previous work, Raman spectroscopy was shown to be an efficient tool for characterizing calcium carbonate (CaCO3) polymorphs and their profile in plain Portland cement (PC) matrices. However, as supplementary cementitious materials (SCMs), particularly fly ash (FA) and ground granulated blast furnace slag (GGBS), are widely used in concrete, establishing the carbonation profile without considering the possible effects of these SCMs could be of little significance to the real world. This paper, thus, investigated the effects of FA and GGBS on the working capacity and reliability of Raman spectroscopy for establishing the carbonation profile in PC blends containing SCMs. The thermogravimetry (TG) analysis was also conducted to verify the results from Raman spectroscopy. The results show that Raman spectroscopy demonstrated a good capacity for differentiating the variation of CaCO3 contents in FA or GGBS blends. However, the incorporation of FA and GGBS into the PC system caused some adverse effects on the quantification of CaCO3 by Raman spectroscopy, which could be attributed to the darker color and weak scatter nature of FA and the high content of glassy phases in GGBS.

Supplementary cementitious materials (SCMs), such as fly ash (FA) and ground granulated blast-furnace slag (GGBS), are often used as a partial replacement of cements to improve the sustainability of Portland cement-based materials and reduce their environmental impact. Superabsorbent polymers (SAPs) can be successfully used as internal curing agents in ultra-high performance cementitious materials by facilitating the hydration process and controlling the water supply in both fresh and hardened states. This paper intends to characterise the physical and chemical properties of SAPs and their sorption properties in different blended cement environments. The swelling capacity and kinetics of absorption of three superabsorbent polymers with different chemical compositions and grading were tested in different cement environments. Experimental results of their sorption performance in distinct solutions, including deionised water (DI), Portland cement (PC), and blended cements (PC-FA and PC-GGBS) and changes in pH of different solutions over time were investigated. The results showed that PC-FA solution had the lowest pH followed by PC-GGBS solution. Moreover, SAPs samples displayed the highest absorption capacities in PC-FA solutions, and the lowest swelling capacities were found in PC-GGBS solutions. Furthermore, SAP with smaller particle sizes had the greatest absorption capacity values in all solutions.

The present paper reports the results of experimental investigations performed to examine the feasibility of using fly ash (FA) and ground-granulated blast furnace slag (GGBS) geopolymers as barrier materials for waste containment facilities. The alkaline geopolymer is a blend of FA and GGBS with sodium hydroxide in concentrations varying from 1 to 5. The important properties of most barrier materials include strength and hydraulic conductivity. While FA can develop compressive strength through pozzolanic reactions, polymerized FA develops tensile strength. For the construction of barriers for landfills with higher heights, tensile strength assumes importance. To further improve the strength, FA can be amended with GGBS. Results indicate that the FA-GGBS mixture in the ratio of 40:60, when cured, exhibited higher strength at any molar concentration. Further, the hydraulic conductivity of the material, which is predominant for barriers in waste containment facilities, is studied. To examine the impact of the presence of heavy metals in the leachates, batch adsorption studies were executed on a 40% FA- 60% GGBS mixture. Leachate with nickel and lead were adapted for their retention within the barrier. It has been observed that the geopolymerized FA and GGBS can retain ionic metals. The retention capacity of heavy metals is due to their precipitation in the voids of the barrier material enabling further reduction in the hydraulic conductivity making geopolymer a sustainable barrier material.

This paper aims at bringing a literature review on the uses and properties of popular industrial and mineral byproduct slag. At the present, most industrial slags are being used without taking full advantage of their properties or disposed rather than used. The use of slag in replacing Portland cement by GGBFS is not very common. The industrial slags, which have cementitious or pozzolanic properties, should be used as partial or full replacement for Portland cement rather than as bulk aggregates or ballasts because of the high cost of Portland cement, which is attribted to the high energy consumption for the production of Portland cement. The traditional way to utilize metallurgical slags in cementing materials is to partially replace Portland cement. The practice of using such mineral admixtures in construction will reduce the need of portland cement and its use in various parts of the world, thus greatly reducing the amount of pollution and pave a way for a cleaner and more economical construction material, of which India is in a great need.
 The literary investigation was carried out on different forms of slag used in construction, i.e. slag aggregates, ground granulated blast furnace slag (GGBFS) and slag mixed with clinker in cement production. Many different properties were examined during the literature review, all segregated into separate categories based on the type of usage, particle size, chemical composition and amount of usage. The base samples ranged from cement sample to concrete cubes. The properties investigated from various sources of literature were compressive strength, flexure strength, duability, abrasion resistance, drying shrinkage, reactivity, hydraulic power, hydration and slump loss. Also properties related to environmental effects like cabonation depth, chloride resistance, sulphate resistance, percentage of water absorption, heat resistance and resistance to freeze and thaw cycles. Its activation with innovative methods and certain reasons were found out which attributed to such behaviour such as glass content, microstructure, pH nature, pore size etc. 
 The behaviour of concrete samples were also investigated with some agents, i.e. samples with some extra chemical admixtures, air entraining agents, and several other mineral and pozzolanic admixtures like fly ash and Rice husk ash. The performance of Slag in different situations ( like its use in reinforced concrete ) and environment (like corrosive sea or marine environment ) was also found out and compared to control concrete. Also differentiation was done on the basis of formation of slag aggregates, i.e. the variation in properties of slag based construction materials vary when slag is created employing different techniques. The investigation will also explain the different problems faced by civil engineers in using slag as a major component in building materials. The review will also explore the future of polyblended cements constituting slag as the main constituent and its scope to be used with agricultural byproducts like Rice Husk ash, or surkhi and other industrial byproducts like fly ash.

The paper investigated the effect of locally sourced fly ash and ground granulated blast-furnace slag (GGBS) on the compressive strength and chloride resistance of concrete. The mix proportion was cementitious material (total of ordinary Portland cement (OPC), fly ash and GGBS): sand: coarse aggregate: water of 1:2:3:0.6 in which 20% by mass of total cementitious materials was replaced by class F fly ash and GGBS. Compressive strength and rapid chloride penetration tests were conducted at 28, 56 and 120 days. The results shows that fly ash and GGBS reduce slightly the compressive strength but improve significantly the choloride resistance of concrete. Within the range of investigation, 10% of fly ash and 10% of GGBS are recommended to replace OPC as they improve the chloride resistance and maintain the compressive strength of concrete.