Effect of Moisture Condition and the Composition of Aggregate from Demolition Waste on Strength and Workability Properties of Recycled Concrete

Large quantities of construction and demolition waste are generated annually, and in many parts of the world, it is disposed of in landfills. Utilizing this waste to produce coarse aggregates for concrete production offers a potentially sustainable approach that mitigates environmental impacts. Despite the widespread encouragement of using recycled aggregates as a substitute for natural coarse aggregates, practical applications remain limited, and the concrete production industry continues to primarily rely on exploiting natural resources. The recycling of concrete waste derived from the demolition of obsolete or damaged buildings as structural concrete has been seldom realized thus far, primarily due to regulatory constraints and concerns regarding technological difficulties. This paper presents a case study to demonstrate that, with meticulous preparation, concrete waste from a demolished building can be rendered suitable for use as structural concrete. The experimental investigation examined how the proportion of recycled aggregates obtained from a demolished building and the moisture content influenced the properties of fresh and hardened concrete. The results revealed an increase in the compressive strength of the hardened recycled concrete as a higher proportion of recycled coarse aggregate was incorporated into the mixture. Moreover, pre-soaked recycled coarse aggregates were found to improve the workability of the recycled concrete mixture significantly. The results highlight the significant potential of utilizing concrete waste as a valuable resource in the production of ready-mix concrete for structural applications, provided that appropriate measures are taken to optimize its properties.