The temperature dependence of the optimum exposure dose for polymerization of polymer-impregnated concrete (PIC) was examined on the mortar specimens containing MMA monomer cured by gamma-rays at the dose rate of 0.9×106R/hr. In addition, the strength of PIC irradiated with gamma-rays in water was compared with that of the one polymerized in air. Furthermore, the effect of size on the attenuation of gamma-rays in mortar was discussed in the present paper.
Judging from the strength of PIC, the optimum total exposure dose is dependent upon the dose rate and temperatute. It is necessary to increase the exposure dose when PIC is polymerized at lower temperatures (Fig. 9). If the polymerization is carried out at the optimum exposure dose, the strength of PIC takes almost the same value, regardless of the dose rate and temperature (Fig. 7). No significant difference is found between the strengths of PIC polymerized in air and in water (Fig. 10). As the exposure dose attenuates about half per 4cm thickness of mortar, the exposure dose of over one megaroentogen at the dose rate of 2.5×105R/hr is required at the center of cross section or at the shadow face of mortar.
