Incorporating waste to develop environmentally-friendly concrete mixes

The inclusion of various waste products in concrete mixes was studied, with the intent of being used in an aviation construction project. The waste products investigated were waste plastic aggregates, fly ash and recycled glass powder as supplementary cementitious materials, waste glass sand as fine aggregate partial replacement, and waste latex paint as a polymeric admixture. The objective of the mix design testing was to develop three concrete mixes which met specific design requirements set by the project whilst reducing greenhouse gas emissions and landfill mass when compared with standard mix designs provided by the concrete plant. A three phase trial mix design process was followed, where the influence of plastic aggregate as a natural aggregate binder replacement was investigated, in conjunction with the addition of fly ash as a supplementary cementitious material, glass sand and waste paint. Through testing for the hardened properties of the concrete mixes, and microscopic analysis of cross-section samples, mix designs which achieved the structural performance objectives were developed. A Life Cycle Assessment to compare the potential environmental impact reduction of the recycled material mix designs was conducted, focusing on the product stage considering the variation in quantity of raw materials (A1) across mixes, and their transport (A2) to batching plant located in Auckland. The LCA found that two of the three recycled material mix designs gave potential environmental impact reductions of over 10% in six of the 7 categories, and over 20% in three of the 7 categories.