In order to recycle concrete wastes, a new processing method for solid
ifying pulverized concrete wastes has been developed using a hydrother
mal hot-pressing method. The effect of addition of fresh cement was ex
amined to further increase the strength of solidified concrete wastes,
Hydrothermal hot-pressing tests were carried out at 200-250 degrees C
with the water content of 10-30 mass% under the pressure of 20 MPa fo
r 20 min. Fresh cement of 0-50 mass% was added to the mixture. It is s
hown that the formation of tobermorite improved the tensile strength.
The tensile strength determined by a Brazilian test reached approximat
ely 13 MPa under the conditions; the temperature:230 degrees C, fresh
cement content :50 mass%, and water content:30 mass%.