Utilization of Industrial and Agro-based By-products to Develop Sustainable Controlled Low Strength Material

Environmental degradation is resulted by unabated resources’ extraction for catering to needs of growing population, GHG-emissions, rising wastes and landfills with harmful leaching in the surroundings. Controlled low strength material (CLSM) is self-compacting flowable materials using small cementing material, fine aggregate and water primarily employed as backfill. Present study aimed at the development of sustainable CLSM suitable for practical applications, by utilization of industrial and agro-based by-products cement kiln dust (CKD) and unprocessed rice husk ash (RHA) through evaluating their properties in fresh and hardened state. RHA substituted natural sand and five CLSM with CKD progressively replacing OPC for 0–100%, binder/aggregate ratio of 1:3 and flowability of 200–250 mm were studied. CLSM mixes using CKD 0–100 kg/m³ and RHA 300 kg/m³, attaining unconfined compressive strength (UCCS) of 0.03–0.31 MPa at 28 days and 0.05–0.48 MPa at 91 days, were excavatable for their long-term UCCS < 2.1 MPa and suited general backfill applications such as voids and abandoned underground structures for 28 days UCCS < 0.50 MPa. Use of by-products diminished the embodied energy (EE) and embodied carbon dioxide (ECO₂). Mix with 50 kg/m³ CKD was best suited with practical requirements of CLSM. CLSM can be sustainable, effective-application for large-scale disposal of by-products. Use of CKD and unprocessed RHA resulted in long setting times and efforts for reduction of the same are recommended for practical application of mixes. Use of some cement content at high by-product replacement is recommended to maintain integrity of specimens. Study’s application near by-product’s source shall minimize transportation energy and help in terms of EE and ECO₂.