A review on utilization of industrial by-products in the production of controlled low strength materials and factors influencing the properties

Disposal of industrial by-products and waste materials in the landfills is posing environmental pollution apart from incurring huge economical cost. Some of these materials could be effectively used in developing structural and non-structural cementitious materials. There are several non-structural applications of concrete, such as filling construction cavities and blinding concrete under the structural members, which requires low to very low strength concrete known as controlled low strength material (CLSM). In a move towards reducing greenhouse gasses generated by the production of cement and effectively using industrial by-products, several natural and waste materials are being utilized in the production of CLSM as a partial replacement of cement and aggregate. These include fly ash, natural pozzolan, silica fume, ground granulated blast furnace slag (GGBFS) and a host of other industrial wastes. In the recent past, the use of CLSM as a cost effective, as well as labor and timesaving alternative for compacted earth backfill has grown substantially. This article presents a review on the utilization of various industrial by-products for the development of CLSM and their influence on the fresh and hardened properties. Although several industrial by products have been used in the production of CLSM, fly ash has been extensively utilized for this purpose with great success due to its favorable morphology that is beneficial in obtaining feasible fresh and hardened properties. The results of various studies demonstrate that the type of industrial waste in the development of CLSM as both partial replacement of cement or aggregate and mix proportion greatly influences the fresh and hardened characteristics of CLSM. A suitable mix proportion for a particular industrial waste is possible to produce sustainable CLSM with desired properties. The review also identifies several other industrial waste materials that can incorporated for developing sustainable CLSM such as construction and demolition waste. Further, a comprehensive analysis of influence of various parameters on the properties of CLSM in this review possibly will form a basis for future research in this area for sustainable development in the prevailing environmental crises.