![]() Īluminosilicates such as fly ash have been used as SCMs in the concrete industry for decades. In addition, using SCMs as PC replacement leads to economical and durable concrete in the long run and further contributes to a sustainable environment by utilizing industrial waste or by-products. One of the most promising ways to reduce clinker production and subsequent CO 2 emissions is to use Supplementary Cementitious Materials (SCMs) to replace Portland cement (PC) in concrete. In 2020 alone, the estimated worldwide cement production was 4.1 giga metric tons (Gt) and this accounts for 5–8% anthropogenic CO 2 emissions and 90% of industrial CO 2 emission. Even the highest maximum thermodynamically possible efficiency in the modern kiln was unable to reduce the emission and energy consumption. The production of clinker in cement is associated with CO 2 emissions due to the thermal decomposition of limestone (raw material) and associated combustion of fossil fuel to produce the required energy. Paste, which is the mixture of Portland cement (PC) and water, is the main component of concrete to impact the mechanical and durability performance including shrinkage. Typically, concrete is composed of 10–15% of Portland cement (PC). It is the most popular building material due to its versatility and durability. Though concrete is not mandatory for human survival, it is the second most-consumed substance in the world having a per capita consumption of two cubic meters annually. ![]() Considering the replacement level of cement, shrinkage, and ecological impact, LC3 proved to be a more sustainable and eco-friendly concrete compared to fly ash. The high autogenous shrinkage in the LC3 blend was compensated by a low drying shrinkage for a specific compressive strength. LC3 hydrated faster compared to fly ash leading to greater autogenous shrinkage. The initial investigation on paste samples highlighted the dissimilarities in shrinkage and hydration of fly ash and calcined clay. Opting for an engineering approach, comparison among different segments of shrinkage i.e., autogenous, drying and total shrinkage of concrete having a specific compressive strength were considered. The chemical and autogenous shrinkage were assessed for paste samples and further investigation were conducted on hydration by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Paste and concrete were prepared using these SCMs for the highest possible replacement of binder without compromising the strength. This study investigates the shrinkage of two sustainable aluminosilicate blends with fly ash or limestone-calcined clay (LC3).
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