Production of Cold-Bonding Pelletized Artificial Expired Cement- Fly Ash Lightweight Aggregates with Various Curing Regime

Abstract

Expired cement (EC) with fly ash can be recycled in artificial lightweight aggregates (ECFLA) manufacturing to manage industrial waste by mixing with fly ash through a cold bonding process, supplying a sustainable material and contributing to circular economy strategies to produce structural lightweight concrete. Four series of (ECFLA) were divided based on curing conditions and foaming agents, including 20 types of (ECFLA) with control mixes; air and water curing were compared, and their effects were investigated on the (ECFLA) properties. The present study identifies the optimum mix combinations. (EC) mixed with fly ash (FA) in varying amounts of 10, 20, 30, 40, and 50 % by weight of EC with and without foaming agent, it contained approximately 22% water by weight. The (ECFLA) was hardened through a cold-bonding air or water curing process for 28 days, followed by testing at different physical and mechanical properties. Particle crushing strength, impact value, specific gravity, and water absorption were tested on the hardened aggregates. The results indicated that it is possible to produce ECFLA from EC in a cold bonding process. The optimum kind of ECFLA was (20EC80FA) mixed with a foaming agent of loose dry density of 862.13 kg/m3, and particle crushing strength was 2.29 MPa at 28-day for 12 mm diameter. According to test results, cement content significantly affected (ECFLA) strength, consequently influencing lightweight structural concretes’ (LWC) compression strength. The highest 28-day compressive strength of LWCs was 42.3MPa for the (EC50FA50) mix.