Recycling of paint-contaminated grit

The impact on the environment of using paint-contaminated grit (PCG) as a p artial or full replacement for sand in Portland cement mortar and asphalt c oncrete mixtures was investigated. The grit waste material originated from abrasive blasting of offshore steel structures. There is a major environmen tal concern regarding the safe disposal of the spent blasting abrasives tha t contain paint chips or paint particles and other debris removed from the surface of the steel structures. This work investigated the potential reuse of PCG in Portland cement concrete (PCC) and hot mix asphalt concrete. Sev eral studies were conducted to establish the integrity of the materials con taining the recycled grit. These included the chemical and physical charact erization of natural sand and PCG, the assay of leaches associated with the grit material for hazardous metal contaminants, such as Cr, Cd and Pb, and the assessment of the mechanical properties of the PCG-substituted mortars by applying special tests (such as Marshall stability and determination of the flow properties) to the PCG-substituted asphalt concrete mixtures. The overall results demonstrated that the potential reuse of PCG in PCC and as phalt concrete mixtures would not pose any environmental threat and could p roduce several benefits, such as reduced disposal costs, protection of wate r sources from improper disposal practices and reduced costs in the product ion of natural aggregates and asphalt cement.