There are increasing concerns on waste disposal and on-demand infrastructure due to continued population growth and land scarcity. The rapid urban development generates enormous amounts of wastes, resulting in the need for proper waste disposal. Considering these severe situations, sustainable utilization of wastes for backfill in construction provides new resources for construction materials and becomes a promising way to solve the problem of waste disposal. In this study, sustainable utilization of wastes was investigated for producing controlled low-strength materials (CLSM) and solidified/stabilized products for backfill. Utilization of various wastes including municipal solid waste incineration (MSWI) bottom ash, contaminated marine mud and sediment was explored.

CLSM is a self-co...[ Read more ]

There are increasing concerns on waste disposal and on-demand infrastructure due to continued population growth and land scarcity. The rapid urban development generates enormous amounts of wastes, resulting in the need for proper waste disposal. Considering these severe situations, sustainable utilization of wastes for backfill in construction provides new resources for construction materials and becomes a promising way to solve the problem of waste disposal. In this study, sustainable utilization of wastes was investigated for producing controlled low-strength materials (CLSM) and solidified/stabilized products for backfill. Utilization of various wastes including municipal solid waste incineration (MSWI) bottom ash, contaminated marine mud and sediment was explored.

CLSM is a self-consolidating cementitious mixture with a compressive strength less than 8.3 MPa. In this study, CLSM was newly designed using MSWI bottom ash and contaminated sediment as raw materials. Up to 80% of waste utilization by mass was achieved with all requirements fulfilled as general CLSM. The compressive strength of the CLSMs made with bottom ash is higher than that of sediment. The formation of C-S-H gel contributes to the strength development and heavy metal immobilization. The mobility of heavy metals in CLSMs fulfilled the U.S.EPA regulatory standards. Above all, the CLSMs are suitable for a wide range of construction applications.

Besides, utilization of contaminated marine mud and sediment individually as solidified/stabilized products was investigated for in-situ backfill. In order to maximize the waste utilization as solidified/stabilized products using cement and pulverized fuel ash (PFA) as binder, mixing 75% by mass of either contaminated marine mud and sediment with 20% and 5% of cement and PFA, respectively, was found to be the optimal mix design. Their compressive strengths reached up to 8.32 MPa and 4.47 MPa, respectively. The formation of C-S-H gel and ettringite is responsible for the strength development and heavy metal immobilization.