Development of solidification technique for recycle of concrete wastes by hydrothermal hot-pressing and its mechanical property

Abstract

A new processing method for solidifying pulverized concrete wastes is presented. The objective of this study was to develop a technology to recycle concrete wastes. Concrete wastes were pulverized and then solidified by a hydrothermal hot-pressing method, which is a press-forming technique under hydrothermal conditions using an auto-clave. The reaction temperature was in the range of 120° to 300 °C, and the reaction time was in the range of 10 to 40 min. The tensile strength of the solidified concrete waste was determined by Brazilian tests. It was shown that concrete waste can be solidified under the above reaction conditions. The measured tensile strength increased with increasing temperature, and a steep increase was observed at the reaction temperatures of 150° to 200 °C. The tensile strength of 5 MPa was achieved above 200 °C. The steep increase in the tensile strength was shown to be due to the formation of tobermorite.