Experimental Investigations on Building Derived Materials in Chemically Aggressive Environment as a Partial Replacement of Soil in Geotechnical Applications

Abstract

Construction and associated demolition processes produce huge amount of solid waste, generally termed as construction and demolition waste (CDW). Management and proper disposal of these wastes is an area of prime concern for modern civil engineers. About 90% of all CDW is composed of building derived materials (BDM) obtained from concrete, bricks, and tiles from structural and non-structural elements of a building. The present study emphasizes on the use of virgin BDM, which conserves natural aggregate, reduces the impact on landfills, saves energy, and thus can provide significant cost benefit. Five types of BDM—crushed lightweight concrete (T1), crushed marble tiles (T2), crushed high strength concrete (T3), crushed normal portland cement concrete (T4), and crushed bricks (T5)—are characterised to assess their compatibility when used in conjunction with local soil. The soil, BDM and soil–BDM mixes are characterized from physical, mechanical, mineralogical, microstructural, and chemical aspects. These tests are then repeated for the aforementioned soil-BDM mixes after immersion in acids. Aggregate impact value (AIV) results on the five types of BDM indicate that T1 and T5 are poorly resistant to impact loads. However, T2, T3, and T4 show relatively better resistance to impact loads and satisfy the requirements for sub-base material standards. Shear strength studies show that the average optimum replacement of soil by BDM is in the range of 17–23% by mass. In order to test the compatibility of BDM in soils containing aggressive chemicals, the properties mentioned above are re-evaluated after exposing the BDM to aggressive chemical environments. The results indicate that the internal angle of friction (ϕ) of virgin BDM is found to vary significantly due to acid attack. The results of AIV after exposing the BDM to acids show that BDM are highly susceptible to chemically aggressive environment. The performance of all types BDM are affected by the presence of acids and appropriate measures must be adopted while using BDM in such chemically aggressive environment. These standards can be used as guidelines in the present study in the absence of specific standards for BDM applications.