Eighth International Conference on The Constructed Environment

Abstract

This paper introduces the engineering properties of Controlled Low Strength Materials (CLSMs) incorporating recycled Calcined Alumino Silicate (CAS) in varying amounts. CLSM, also known as structural fill, is a material used as void fill and backfill in construction practices. Primarily used as a replacement for compacted soils, CLSMs provide an advantage for difficult to fill voids by filling them more quickly than by traditional methods. Because the compressive strength requirement is much lower than structural concrete, CLSMs provide a unique opportunity to incorporate recycled materials where the later may not allow. Specifically, this study evaluates CLSM mixtures containing recycled CAS, cement, fly ash, water, and virgin fine aggregate. The mixture proportions were designed for increasing amounts of recycled CAS content with increments of 25% by fine aggregate weight. The CLSM’s flowability, air content, bleeding, unit weight, and compressive strength were measured and analyzed for suitability for field use. The study found that increasing the amount of recycled CAS in the CLSM mixtures decreases the removability modulus by lowering the unit weight with decreasing the compressive strength over the long term. Therefore, the structural fill evaluated in this study was determined acceptable based on the flowability and removability modulus when recycled CAS was included in the mixtures.