Recycling Fine Aggregate from Demolished Hollow Concrete Block for Green Concrete in Ethiopia

Construction industry in Ethiopia is growing fast due to rapid urbanization and accommodation demand for affordable housing for residents. This activity generates a large amount of construction and demolition wastes, which are commonly disposed of as landfill and cause environmental and economic impacts. Recycling construction and demolishing waste is one of the viable solutions to reduce environmental pollutions and makes construction sustainable by lowering the dependence on natural and non-renewable resources. In this study, the effect of recycled fine aggregate from the demolished hollow concrete block on the workability, density, and compressive strength of concrete was studied. A comparative analysis of the experimental results of fresh and hardened concrete properties with different replacement ratios of natural river sand by recycled fine aggregate is presented in the paper. Concrete mixes containing 25 %, 50 %, 75 %, and 100 % replacement of natural sand with the recycled fine aggregate were tested. The test results indicated have lower physical properties than the control, but they have satisfied the ASTM requirements. The replacement of natural river sand by recycled hollow concrete block slightly affected the workability, density, and compressive strength of the concrete. The performance of the concrete containing recycled fine aggregate decreased with an increase in the percentage of replacement of fine aggregate increased, and the targeted compressive strength was met up to 50 % replacement Therefore, this work demonstrated that the suitability of using demolished hollow concrete block as fine aggregate, and this could reduce the environmental impact due to waste disposal and sand mining.

Keywords:Compressive strength; Concrete; Demolition hollow concrete blocks; Recycled fine aggregate