Thermo- mechanical and microstructural characterization of LECA and low carbon cement based lightweight mortar using box behnken design, and embodied energy analysis

Abstract

Lightweight aggregate mortar (LWAM) containing different kinds of supplementary cementitious materials (SCMs) has gained significant attention as a sustainable construction material. However, the behavior of this type of mortar at elevated temperature conditions, such as those encountered in fire events, remains largely unexplored. In this study, the effect of different temperatures (i.e. at 27⁰C, 110⁰C and 850⁰C) on the Thermo-mechanical and microstructural properties of LWAM containing low grade limestone slurry (LgLS), class- F fly ash (FA), and lightweight expanded clay aggregate (LECA) is investigated. LgLS and FA were replaced with ordinary Portland cement (OPC) in the range of 0–20%, and 0–30% by weight. River sand was replaced with LECA, ranging from 0% to 50% with an increment of 25% in river sand fractions. Along with this, statistical modelling and parametric optimization were done using Box Behnken Design (BBD) of Response Surface Methodology (RSM). Advanced characterization techniques such as- Field Emission Scanning Electron Microscopy (FE-SEM) and X-ray Diffraction (XRD) were performed to investigate the effect of higher temperatures on the microstructure and hydration products of LWAM matrix. Embodied energy analysis was also carried out to investigate the environmental assessment along with cost analysis. It was concluded that as compared to the reference LWAM mix at 27 °C; CS at 28 days was increased by 15–25% at temperature of 110 °C for different mixes, while the same was drastically decreased by 60–64% at higher temperature i.e. 850 °C. Embodied energy analysis predicted that carbon emission can be minimized by about 25%, which is the need of the recent era to meet sustainable development goals.