To investigate thermal hydration mechanical chemical couple phenomena is an important issue of the high-level radioactive waste disposal and a key indicator of artificial barrier system. Major objectives of the thermal and thermomechanical site characterization include the status of the environmental and safety condition. Several research reports are aimed at the barrier layers for heating from radioactive waste disposal. This study helps to establish the pore pressure under heat conditions for bentonite-sand mixture, which is completely undrained condition and unexhausted condition, and consider occurrence mechanics of pore pressure in macro-micro void structure in 80 degrees Celsius temperatures. All of specimens are statically compacted in the developed mold. The developed mold has interesting points that two special pressure sensors are installed at lateral surface in the mold. The sensors employ the high of 150 degrees Celsius and is possible to be high temperature resistance. The prepared specimens are unsaturated specimens and saturated specimens, and silica sand are mixture into sodium bentonite and calcium bentonites. The mixture ratio has a range from 0 % to 50 % for silica sand. The developed mold including specimens is placed into a thermostat oven, and heating application is applied isotropic conductivity form 20 degrees Celsius to 80 degrees Celsius. The pore pressures measured at lateral portion in specimen indicate with elapsed time. Other hands, the small size sensor measured temperature in the developed mold, which has an empty (i.e., no placed specimen). The temperature measured by the small sensor is possible to estimate the specimen temperature according to increase temperature in the thermostat oven. The obtained results are significant as followings; The measured pore pressures are obviously increase with increment of the temperature, and the sand mixture ratio has effort, and it is not so much.