Field investigation of ammonia alkali soda residue-based foamed concrete as a subgrade filler
摘要
Ammonia alkali soda residue-based foamed concrete (A-FC) is a novel lightweight material produced by partially replacing ordinary Portland cement (OPC) with ammonia alkali soda residue (AR) and ground granulated blast furnace slag (GGBS). As a representative solid waste-based foamed concrete, A-FC offers a promising approach for the high-value utilization of AR. However, to date, no field tests have been reported on the using of A-FC as a subgrade filler, and its road performance has yet to be determined. This study conducted a comprehensive field investigation to assess the feasibility of using A-FC as a subgrade filler. Key parameter, including wet density, flow value, core compressive strength, California bearing ratio (CBR), resilient modulus, deflection, earth pressure, settlement, and temperature, was measured to evaluate its road performance. An on-site preparation method for A-FC was proposed through optimization of the mixing scheme. A-FC was successfully used as a subgrade filler for the Lianyungang–Suqian expressway. The wet density, flow value, core compressive strength, CBR, resilient modulus, and deflection of A-FC subgrade, along with the settlement of road foundation, all satisfied the design and specification requirements. Specifically, the wet density of A-FC ranged from 579.95 to 625.05 kg/m3, and its 28d compressive strength ranged from 0.62 to 1.59 MPa, demonstrating its excellent road performance. Hydration of OPC and GGBS raised the internal temperature of A-FC at a rate of approximately 1.02 during the initial hydration stage. The internal temperature of A-FC was unaffected by atmospheric temperature, indicating its excellent thermal insulation performance. With its low weight and high strength, A-FC can significantly reduce soil pressure and foundation settlement. Consequently, A-FC holds considerable potential for large-scale application in road construction on soft soil areas.