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The World Bank study predicts that 4 °C warming will bring high temperatures, sea-level rise, and saltwater intrusion to coastal areas, damaging coastal concrete structures. Increased CO2from industrialization exacerbates this, necessitating durable, low-carbon concrete. Combined use of fly ash (FA) and ground granulated blast furnace slag (GGBFS) as high-volume OPC replacements boosts performance while reducing concrete’s carbon footprint. In this perspective current study examines the durability of concrete against aggressive agents (H2SO4, MgSO4, NaCl, and CO2) causing premature deterioration of concrete structures. Initially, three cost-effective sustainable concrete mix designs were developed, incorporating 50% replacement of OPC with locally available supplementary cementitious materials, specifically FA and GGBFS. These mixes were then evaluated for their mechanical and durability performances. The impact of aggressive ions (SO42−, Cl−, and CO32−) was studied by examining the changes in mechanical performance and phase assemblages. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques were used to estimate the phase compositions. Ternary blended concrete having 50% OPC+ 30% GGBFS + 20% FA exhibited optimal synergistic performance, enhancing pozzolanic and hydraulic reactions for better resistance to harmful ions. The sorptivity test confirmed that as the GGBFS content increased, the sorption rate decreased, indicating the higher reactive nature of GGBFS to that of FA. Deleterious compounds formed due to the action of SO42-, Cl-, and CO32-were identified to be ettringite (Ca6Al2(SO4)3(OH)12.32H2O, AFt) and gypsum (CaSO4.2H2O, Gy), Friedel’s salt (Ca4Al2(OH)12Cl2.4H2O, Fs) and polymorphs of calcium carbonate (CaCO3), respectively through TG mass loss curve. These results were corroborated by FTIR analysis, which showed predominant characteristic bands at 662 cm−1for SO42−, 459 cm−1for Mg–O stretching, 790 cm−1for Al–OH bending, and 1431-1443 cm−1for C–O, confirming the presence of the deleterious compounds.

The prohibition of river sand mining has drawn the attention of researchers in finding practicable alternatives. In the approach of finding these alternatives, it is essential to ensure minimal or zero impairment to the ecological balance, which can be mainly attained by making use of industrial waste/byproducts. The wastes from the mining industry are the major contributors in causing impairment to the environment, and their influence on the stability of mortars on using as fine aggregates needs to be systematically investigated with the view of long-term performance concerns. Thus, the present study explores the applicability of mine tailings and finding the optimum dosage in cement mortars by investigating the engineering properties and microstructure development with the aid of qualitative and quantitative analysis associated with hydration products. The studies confirm that the increased consumption of portlandite for secondary hydration reactions followed by the additional formation of calcium silicate hydrate (CSH) and calcium aluminum silicate hydrate (CASH) phases in mine tailing-based mortars helped in achieving a quality microstructure. These additional formations of CSH and CASH phases are also confirmed through Fourier transform infrared spectroscopy by identifying the shift of Si-O-Si stretching vibration bands toward a lower wavenumber. The lowering of calcium/silicate atomic ratio and increased formation of mineralogical compounds related to CSH and CASH in x-ray diffraction patterns also confirms the same. Gismondine, chabazite, and hillebrandite are the additional phases formed and found to take part in refining the pore structure. This enhanced performance of mine tailing mortars was also verified with the aid of a modified Andreasen and Andersen particle packing model. The formation of high-quality microstructure is reflected in the hardened properties of optimized cement mortar in the proportion of 20 % for iron ore tailing and 30 % for copper ore tailing.

The present research assists in resolving the issues allied with the disposal of industrial solid wastes/industrial by-products (IBPs) by developing sustainable IBPs based cement mortars. The applicability of IBPs as a feasible alternative to river sand in cement mortar has been evaluated by investigating the synergy among the ingredients, resulting engineering properties and microstructural developments at early and late curing ages. The study could effectively substitute 30% volume of river sand with bottom ash and 50% in the case of slag sand mortars. The experimental outcomes disclose that the practice of IBPs as fine aggregate enhances the engineering properties of mortar and the optimum replacement level lies at 10% and 40% usage of bottom ash and slag sand, respectively. The advanced characterization studies and particle packing density illustrate the refinement of pores by void filing action and accumulation of additional hydration products through secondary hydration reactions. The consumption of portlandite followed by increased hydration products formation observed through thermogravimetric analysis, X-ray diffraction analysis and energy dispersive X-ray spectroscopy that confirmed the contribution of finer fractions of IBPs to secondary hydration reactions. This constructive development was also observed from the lowering of wavenumber corresponding to Si–O–Si/Al vibration bands in Fourier transform infrared spectroscopy spectra. The improved microstructure resulted in enhancing the compressive strength by 9.01% and 18.18% in optimized bottom ash and slag sand mortars, respectively at the curing age of 120 days. Similarly, the water absorption reduced by 1.03% and 1.24% in bottom ash and slag sand mortars, respectively.

ABSTRACT This paper presents the results of an experimental investigation carried out to evaluate the microstructure, hydration and nanomechanical properties of concrete containing metakaolin. The properties of concrete containing metakaolin [...]

ABSTRACT The effects of nano-[Al.sub.2][O.sub.3] addition on the early-age microstructural properties of cement paste is reported in this paper. The study was limited to evaluation of properties of cement paste [...]

ABSTRACT Fly ash and limestone powder are found to be the traditional materials to be used in controlling the segregation potential and deformability of fresh SCC. This research deals with [...]

The utilisation of biochar in concrete has attracted considerable attention due to its potential in enhancing the properties and sustainability of this construction material. This in-depth review delves into various aspects of biochar-concrete composites. It commences by defining biochar and exploring its production methods, physical and chemical properties. Additionally, the review provides an overview of concrete, emphasising its composition, properties and the challenges associated with traditional production methods. The incorporation of biochar in concrete brings forth several benefits, such as improved strength and durability, enhanced thermal properties and the potential for carbon sequestration. The paper examines the production process of biochar-concrete composites, covering aspects like incorporation methods, biochar selection, mixing techniques and quality control measures. Furthermore, the sustainability aspects of biochar-concrete are evaluated, considering its environmental impact, life cycle assessment, carbon footprint reduction and economic feasibility. The review also addresses the challenges and future perspectives of biochar-concrete composites, along with opportunities for research and development. This comprehensive review presents valuable insights into the properties, production and sustainability of biochar-concrete composites. It serves as a guide for further advancements in the realm of sustainable construction.

The elastic modulus, hardness, and volume fractions of different phases of ambient-cured fly ash (FA) geopolymers were determined using the nanoindentation method. A low-calcium FA was blended with either 15% GGBFS or 10% OPC to accelerate curing and the effect of 2% nanosilica (NS) was studied. It was found that the inclusion of NS increased the volume of reaction product from 70% to 79% and reduced the porous phase from 13% to 7% in the FA only geopolymer. Similar changes were also found in the OPC or GGBFS blended geopolymer specimens. The reduction of the porous phase correlated well with the porosity determined by mercury intrusion porosimetry tests. Thus, the improvement in the properties of ambient-cured geopolymers by the inclusion of NS was established using the nanoindentation characterization.

This review paper provides an extensive assessment of the diverse roles played by water-soluble polymers in cementitious materials. It commences with an introduction that provides a thorough overview of the background, objectives and limitations of the review. Subsequently, the various types of water-soluble polymers, encompassing natural, semi-synthetic and synthetic variants, are examined in detail, alongside an exploration of their working mechanisms within cementitious materials. Mechanisms discussed include entanglement and association, adsorption and complexation, as well as bridging. Furthermore, this review delves into the influence of water-soluble polymers on the microstructure, fresh properties, mechanical properties and durability of cementitious materials. A comprehensive analysis of the challenges and opportunities associated with the implementation of water-soluble polymers in cementitious materials is also presented, followed by a summary of the key findings and recommendations for both practical applications and future research endeavors. Overall, this review provides invaluable insights for researchers and practitioners, shedding light on the multifaceted functions of water-soluble polymers in cementitious materials.

This review paper presents a comprehensive analysis of Life Cycle Assessment (LCA) methodologies applied to construction materials. It begins with an introduction highlighting the significance of LCA in the construction industry, followed by an overview of LCA principles, phases and key parameters specific to construction materials. The methodological approaches utilised in LCA, including inventory analysis, impact assessment, normalisation, allocation methods and uncertainty analysis, are discussed in detail. The paper then provides a thorough review of LCA studies on various construction materials, such as cement, concrete, steel and wood, examining their life cycle stages and environmental considerations. The review also explores recent advances in LCA for construction materials, including circular economy principles, renewable alternatives, technological innovations and policy implications. The challenges and future directions in LCA implementation for construction materials are discussed, emphasising the need for data quality, standardisation, social aspects integration and industry-research collaboration. The provides valuable insights for researchers, policymakers and industry professionals to enhance sustainability in the construction sector through informed decision-making based on LCA.

The nanomechanical properties of cementitious materials determined by nanoindentation largely depend on the surface roughness and intrinsic material porosity of the samples. Studies have shown that high surface roughness causes an overall reduction in the measured indentation modulus and hardness. Therefore, it is important to reduce the surface roughness to a desirable value by means of polishing. However, polishing causes damage to the cement matrix. Thus, the most challenging task is to obtain a reasonable surface roughness with minimum disturbance to the microstructure of the samples. This paper discusses an effective surface preparation technique that would meet the roughness criteria for nanoindentation. With the application of Taguchi method, the optimum parameter combinations and relative contributions of various controlling factors such as force, speed, and time of polishing were determined. A second-order response surface model was developed based on signal to noise ratio to establish the relationship between the controlling factors and surface roughness. Finally, the predicted surface roughness values from both Taguchi method and response surface model were compared with the experimental values of the optimized confirmation runs and a good agreement was achieved.

In this study, the properties of vinyl ester/glass flake (VE/GF) coating on mild steel plates was investigated to determine its anti-corrosion performance. The corrosion penetration rate of VE/GF coated and uncoated mild steel was evaluated using immersion tests for 20 days. Corrosion resistance of the coating was evaluated in various corrosive environments viz. 5% HCl, 8% HCl, 5% NaOH and 7% NaOH. The mild steel plates were coated with four different thicknesses of VE/GF coating and a comparative analysis was carried out to evaluate the corrosion protection efficiency. Scanning electron microscopy was carried out before and after the immersion test to study the morphological changes and products of corrosion.