Recycling of different industrial wastes as supplement of cement for sustainable production of mortar
Rishath Sabrin, Md. Shahjalal, Hasiba Afrin Eema Bachu, Mirza Md Lutful Habib, Tamanna Jerin, A. H. M. Muntasir Billah
Abstract
Day by day, soaring demand for natural resource devouring and CO2-producing material, cement in the construction industry, poses enormous ecological risk, accelerating the requirement of an alternative or supplementary cementitious material (SCM). In contrast, retrieval of a massive amount of industrial waste needs proper attention to alleviate the environmental burden. This research aims to utilize three common industrial wastes: recycled concrete dust (RCD), ladle furnace slag (LFS), pyrolysis carbon black (PCB) as SCM in cement-based composites, offering a sustainable approach towards the green atmosphere. The study experimentally compares the performance of 13 different mortar mixes, substituting the ordinary Portland cement (OPC) with varying weight percentages (0% as control, 5%, 10%, 15%, and 20%) of each waste. Including chemical composition analysis of OPC and alternative binders; several physical properties, mechanical properties, particularly compressive strength, flexural capacity, strength at elevated temperatures, strength activity index (SAI), durability characteristics are performed on afore-mentioned mortar mixes. Moreover, the failure pattern, microstructure, and presence of chemical substances in the composites are examined. This investigation also highlights the strength-CO2 emission measure and economic viability of the material considering waste processing charges. The results satisfy ASTM standard strength requirements for all 13 mixes, a minimum 75% SAI was achieved in all cases except 20% cement replacement level of PCB. Compared to the conventional control mix, 5% RCD blended mortar exhibited 9% higher compressive strength. In contrast, PCB showed a continuing decline in compressive strength, with a reduction up to 45% for 20% replacement level. Incorporating 10% slag as SCM, improved performance was obtained in terms of compressive strength (+7.9%), flexural strength (+11.7%), strength at 800 °C (+22%), strength-CO2 ratio (+15%), economy index (+9.1%) while compromising workability (−62.7%) and durability.