Utilising Waste Paint and Waste Glass in Concrete

Abstract

Significant volumes of waste paint and stockpiles of crushed waste glass bottles exist in New Zealand and both are an environmental concern, prompting this doctoral study which investigated the viability of concrete that utilised waste paint as a replacement for conventional water-reducing and air-entraining admixtures and a partial replacement for mixing water, and crushed waste glass as a partial replacement for natural coarse and fine aggregates. An in-depth study on the effects of waste latex paint on the fundamental concrete properties is reported, by initially finding an optimum dosage of waste latex paint to use, and subsequently analysing the strength and durability properties of concrete containing waste latex paint. A petrographic examination on the effects of waste latex paint on concrete hydrates and microstructure was also undertaken. Concrete mixes incorporating waste glass and supplementary cementitious materials weretested to find an optimum mix based on fundamental properties such as air content, compressive and flexural strength, and most importantly the problematic alkali silica reaction. The use of electron microscopy was used to confirm the formation of alkali silica gel. The hardened properties of concrete utilising a combination of waste latex paint and waste glass were also investigated, with electron microscopy used to examine the effect of waste latex paint on the formation of alkali silica gel. Lastly, a set of field trials were undertaken to test concrete that utilised waste latex paint and waste glass in commercial low strength concrete applications whilst testing the fresh and hardened concrete properties and attempting to achieve desired performance requirements. Test results illustrated that concrete with 12 L/m3 of waste latex paint is appropriate for use in non-structural low strength concrete applications such as footpaths and driveways. The waste glass used had a negative impact on all concrete properties, and it was considered necessary to use microsilica in concrete utilising waste glass in order to increase strength and mitigate the alkali silica reaction.