Studying Thermal and Mechanical Properties of Recycled Concrete by Using Ceramic Aggregate

Ceramic aggregate has the characteristics of light weight, heat insulation, and low cost, and recycled aggregate is a type of green material that realizes the re-crushing of construction waste. This paper studied the impact of replacing natural coarse aggregate with ceramic aggregate and natural sand with recycled fine aggregate, on the physical, mechanical, and thermal properties of concrete. Recycled fine aggregate was used to completely replace natural sand. A total of five concrete mixes (including a reference mix) were prepared with different levels of ceramic aggregate (0%, 30%, 50%, 70%, 100%). Density, compressive strength, thermal conductivity, and thermal inertia index were measured to evaluate the performance of each mixture, and ceramic concrete board and hollow blocks were designed for testing the thermal properties. Results of testing show that density, strength, and thermal performance are interrelated. The smaller the density, the lower the strength, and it indicates that ceramic aggregate has a negative influence on strength in concrete. Meanwhile, the smaller the density, the higher the thermal resistance, and the addition of ceramic aggregate can improve the thermal insulation of concrete. The mechanical and thermal properties are both affected by the ceramic replacement ratio. Ceramic aggregate improves the thermal properties of recycled concrete, and the negative influence of ceramic aggregate on compressive strength can be controlled by the replacement ratio of aggregate in concrete. Based on the overall comparison and analysis, a mix with 50% ceramic aggregate shows relatively better strength and thermal insulation compared to other mixes. The use of ceramic aggregate in combination with recycled fine aggregate can effectively reduce the environmental pollution and make an economical substitute for their natural counterparts.