Strengthening of hydrothermal hot-pressed concrete waste by the addition of slag

This paper discusses the effect of addition of granulated blast furnace slag on the tensile strength of solidified concrete wastes using a hydrothermal hot-pressing method. Blast furnace slag of 0-100 mass% was added to the concrete waste and NaOH solution was used as alkali-activator. Hydrothermal hot-pressing tests were carried out at 250 °C with the water content of 10-30 mass% under the pressure of 20 MPa. The tensile strength of solidified bodies was determined by Brazilian test. It was shown that the formation of tobermorite and C-S-H compound improved the strength. The tensile strength reached at 13 MPa under, the following conditions; slag content: 50 mass%, water content: 20 mass%, NaOH addition: 1.75 mass%.