MEASURING METHOD OF PREMATURE STIFFENING ZONE FORMED AT THE TOP SURFACE AFTER HIGH-STRENGTH MORTAR PLACING

This paper discusses a measuring method of the premature stiffening zone formed at the top surface after placing of high-strength mortar with a water-binder ratio below 0.2. In this experiment, first a measuring method of the premature stiffening zone was devised by using penetration resistance measurements. The penetration resistance distribution, resistivity distribution and moisture content measurements of mortar specimens simulated high-strength concrete with a design strength of approximately 150N/mm2 were then conducted to assess the appropriateness of the measuring method of the premature stiffening zone. The results reveal that the measuring method was applicable to determining the occurrence and approximate depth of premature stiffening zone for high-strength mortar.