Research Projects

Introduction The Indian construction industry is expected to touch 39.10 trillion rupees by 2029 [1]. While infrastructure continues to grow, it is well known that ordinary Portland cement (OPC) production constitutes 8-11% of anthropogenic CO₂ emissions [2,3], while the Indian cement industry is responsible for ~12% of industrial emissions [3]. Considering India’s climate commitments of net-zero emissions by 2070 and development goals by 2047, there is a pressing need for sustainable alternatives to OPC. One common way to lower the carbon footprint of concrete is by partially replacing OPC with industrial by-products like silica fume (SF), calcined clay (CC), fly ash (FA), slag (GGBS), and ground limestone (LS). Recent advancements, including Limestone Calcined Clay Cement (LC3), indicate that substituting clinker up to 50% can yield performance equivalent to OPC regarding strength and durability while substantially reducing CO₂ emissions [4,5]. Nonetheless, extensive use in India is constrained by material variability, insufficient understanding of hydration and durability behaviour, and the absence of methods for predicting the performance of concrete made with the materials in Indian conditions. Literature review The production of blended cements made with OPC and high-volume supplementary cementitious materials (HV-SCMs) is gaining global attention due to its potential for significant CO₂ reduction [2]. In India, the typical replacement levels of OPC with SCMs are 5-15% for CC, SF, and Metakaolin [6,7], 15-30% for FA [7], 25-50% for GGBS [7], and 50% when a combination of CC+LS is used [5]. However, the OPC content is rarely reduced below 50% due to the required strength and durability targets. Research has shown that HV-SCMs blended cements, including 30-80% FA, can perform similar to or better than 100% OPC systems [8,9]. Likewise, 30-50% GGBS [10,11], and 30-50% LC3 shows the similar behaviour [5,12,13]. The research done on HV-SCM show significantly refine the pore structure and reduces porosity and pore connectivity [9,12,13], reduced chloride diffusion [9]. Also, thermodynamic modelling and a pore partitioning model has been use to predict the microstructure parameters of HV-SCM [14–16]. The challenge with reducing the clinker content below 50% is the lack of available tools to appropriately design concrete mixtures with such low clinker contents and the potential risk of carbonation [17]. In this work, multiscale studies on the properties of HV-SCM systems will be carried out. The microstructure, porosity, and pore volumes will be studies and linked to the mechanical and durability properties of HV-SCM concrete. The experiments will be used to help develop a model to predict the mechanical and durability performance of low-clinker concrete based on existing thermodynamic and pore portioning models [16] which can then be used to proportion concrete mixtures containing HV-SCMs in the Indian context.