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Research on the combined substitution of supplementary cementitious materials (SCMs) has already demonstrated that it might be one of the few viable options to produce low-carbon concrete at scale. This paper presents an experimental investigation on the performance and durability of rice husk ash (RHA) and calcined clay (CC) in ternary blended concrete exposed to chloride attacks under wet/dry cycles. Portland cement (PC) was replaced by RHA and CC up to 50% by weight to produce low-carbon concrete. Samples were subjected to wet/dry cycles in 3.5% NaCl water, with mineralogical composition and microstructure development before and after exposure analysed by TGA-DSC, MIP, XRD, and SEM. The durability of the concrete against wet/dry cycles was investigated in terms of compressive strength, water absorption, open porosity, density, thermal conductivity, and electrical resistivity. The results showed that concrete mixes with CC and RHA up to 60% exhibited an increase of 33% in compressive strength, followed by minimal changes in water absorption. While a decrease in electrical resistivity was measured in all samples with RHA and CC, increasing the CC content to 50% resulted in improved resistance to chloride penetration. Increasing the CC content resulted in a more refined microstructure, with an overall decrease in porosity of up to 32% compared to the control series. While RHA alone did not contribute to significant improvements after wet/dry cycles, the combined substitution of RHA and CC at SCM replacement levels of 60% showed an overall improvement in hardened properties and durability. This investigation provides valuable insights into the long-term performance and strength of innovative low-carbon concrete. [ABSTRACT FROM AUTHOR]

Nanomaterials have emerged as a future application to concrete technology due to their unique composition. This study presents a review of nano CaCO3 in terms of microstructure, rate of hydration, consistency, flowability, setting time, workability, compressive strength, sorptivity, chloride resistance, and corrosion resistance. A remarkable decrease in pores and chloride ion penetration can be observed from the study. Compared to the controlled concrete, the addition of 1% nano CaCO3 also resulted in the reduction of the chloride diffusion coefficient. Compressive strength showed a significant improvement with the inclusion of 1-2% nano CaCO3, however, increasing its quantity showed reduction in compressive strength property. The accelerated hydration reaction forming supplementary C-S-H gel observed in the concrete containing nano CaCO3 has remarkably improved the microstructure of the mix by reducing its porosity. This study is an initiative to accumulate findings of nano-materials for its broad acceptance and future scope of work. [ABSTRACT FROM AUTHOR]

Abstract The present study examines the feasibility of using marble powder in a better way with the use of supplementary cementitious materials. Sand was partially replaced with marble powder up to 15% and cement was partially replaced with the supplementary cementitious material in nine variant concrete mixtures. Two supplementary cementitious materials, silica fume, and metakaolin were added to enhance the pozzolanic activity in the concrete mixtures for maximum utilization of marble powder. To assess various properties of concrete made with marble powder and supplementary cementitious materials, tests like compressive strength, split tensile strength, ultrasonic pulse velocity, carbonation, and microstructure analysis were conducted. Moreover, marble powder was used as a partial substitution for cement in preparation of blended cement pastes. Soundness characteristics and setting behavior were determined on blended cement pastes. The result shows durability properties of concrete on replacement of 15% sand with marble powder were enhanced with the use of supplementary cementitious materials such as metakaolin and silica fume but metakaolin proved to be more effective relative to silica fume. No adverse effect was observed on the expansion and setting behavior of cement paste due to the replacement of cement with marble powder. Highlights • Pozzolanic activity in the marble powder concrete was enhanced with the use supplementary cementitious materials. • The optimal results were investigated with 15% sand replaced by marble powder and 10% cement replaced by metakaolin. • The carbonation depth of concrete decreased on replacement of 15% sand with marble powder and with the use SCMs. • Metakaolin showed better results as compared to silica fume in marble powder concrete. • The utilization of marble powder and silica fume will lead to sustainable development. [ABSTRACT FROM AUTHOR]

Self‐compacting concrete (SCC) was developed in 1988 and introduced by Professor H. Okamura to achieve durability of structures with low skilled laborers. The three properties of SCC that differentiates it from traditional concrete are passing ability, filling ability and segregation resistance. The present study highlights the developments concerning SCC in the period from 1995 to 2017. This information is important for researchers and professionals working in this area. SCC can be optimized to a larger extent to find the best alternative either by use of additives or tailor‐made mix design. Based on different principles and parameters, design methods can be categorized into six classes namely empirical design method, statistical factorial design method, strength‐based design method, rheology of paste method, particle packing method and Eco‐SCC mixture design method. To develop SCC with high quality a suitable method can be chosen depending upon the situation and application. [ABSTRACT FROM AUTHOR]

The versatile applicability of glass products has brought a drastic increase in the amount of glass waste generated, urging to its proper utilization. Light-weight expanded glass is a type of sustainable artificial light-weight aggregate produced by mixing glass wastes and expansive agents under special conditions. The highly porous granules are efficient thermal insulating light-weight material primarily used to prepare light-weight concrete. Over the past few years, extensive research has been carried out to improve the properties of concrete incorporated with expanded/foamed glass. This paper is aimed to present an in-depth review of expanded glass aggregate in terms of its composition, flowability, thermal insulation, physical, mechanical, and durability properties. Special emphasis has been given to study the influence of alkali-silica reactions on the behavior of expanded glass concrete, and the results were encouraging despite the presence of a high amount of reactive amorphous silica in the expanded glass. This study is a novel initiative that accumulated the findings of expanded glass aggregate for its broad acceptance and usability in construction industry giving a promising solution to circular economy and an insight to cleaner technologies. There is plenty of research showing feasibility of glass in variant fields but widened research on expanded glass aggregate has not been presented in the past. [Display omitted] • Gives an insight to circular economy and cleaner technologies. • Suitable to use as a structural concrete for even lower density of 1000 kg/m3. • Excellent frost resistant, prohibits alkali-silica reaction expansion in mortar. • Density and thermal conductivity reduces with Increase in expanded glass aggregate. • Increase in the concentration can increase the risk of carbonation. [ABSTRACT FROM AUTHOR]

• The novel approach accommodates WFS in large volumes without compromising other properties of the concrete. • Adding up to 50 % WFS to concrete can prove beneficial to industries. • WFS contains more than 80 % silica and alumina; the ratio of SiO 2 /Al 2 O 3 was 2.5. • WFS played the role of VMA, however, increases the water / HWRA demand of the mix. • The presence of WFS improved robustness of self-compacted concrete. Waste foundry sand (WFS) is a solid waste generated from the metal casting industries around the world, problem of its disposal and utilization are burgeoning universally. WFS is termed as a hazardous material due to the presence of organic and inorganic materials that are capable of contaminating the environment and can cause serious health issues. The study aims to re-utilize WFS in large volumes in concrete as a fine aggregate. The major impediment in the production of self-compacting concrete (SCC) is the robustness of concrete mixture. To study the effect of WFS on the robustness of SCC, six different mixtures were prepared having WFS up to 50 % at regular intervals of 10 % employing metakaolin as a substitute for cement at a constant ratio. It was revealed that the incorporation of WFS improved the robustness behavior of SCC, despite the change of ±10 L/m3 water dosage in SCC mixtures, all the mixes were observed falling in the same classes. Incorporation of 40 % WFS increased compressive strength by 17.2 % relative to control concrete at 56 days curing ages. The findings of the study suggest that WFS can be used in large volumes for the development of SCC without compromising its properties. [ABSTRACT FROM AUTHOR]