Environmental Sustainability Assessment of Alternative Controlled Low Strength Materials as a Fill Material

Controlled low strength material (CLSM) can be used as a backfill material while constructing utility trenches. Numerous research suggested integrating industrial waste products in the design of these cementitious mixtures for CLSM. This study compares various CLSM designs that incorporate industrial byproducts to a traditional aggregate backfill design and perform a comparative sustainability assessment of them. In the present study environmental sustainability assessment of alternative CLSM materials has been assessed for a proposed utility trench of depth 3 m, width 3 m, and stretch of 100 m in Dhanbad Municipal Corporation. The assessment has been carried out using Ecoinvent 3.0 database, TRACI 2.1 as the midpoint impact method through a commercially available environmental sustainability assessment tool SimaPro 9.4.0.2. The study incorporated the streamline approach of cradle to gate. It was observed that the impact of coal mine overburden based controlled low strength material (CLSM_OB) is the most sustainable option for the backfill material with relative 39% impact in ozone depletion, 41% fossil fuel depletion, and 65% ecotoxicity. In addition, the relative impact on human health is 80%, ecosystem quality is 52%, and resource depletion is 67% by CLSM_OB, followed by CLSM_FS, CLSM_WTS, and M5 Concrete in increasing order of impact.