Reinforcing method for littoral structures in thermal and nuclear power stations

Recently, the thermal and nuclear power stations in Japan are often exposed directly to severe sea condition owing to the situation of their location and construction. In this paper, underwater asphalt construction method (asphalt mats, sand mastic) and hydrocrete construction method (underwater unseparable concrete) are described as the reinforcing method for littoral structures such as breakwaters, protective banks, water intakes and discharge chennels. The asphalt mats are formed in precast state, burying reinforcing core materials such as glass fiber nets or wires in asphalt mastic, the mixture of asphalt, filler and aggregate. The sand mastic is the fluid asphalt compound, in which asphalt, stone dust and sand are heated and mixed, and is poured and solidified into the gaps in rubble mounds in water, to reinforce them. The hydrocrete is the underwater concrete of high quality made by blending special polymer compound to ordinary concrete, which does not separate during free descent in water, and the contamination of water quality is scarce. The features and applications of these construction methods are explained. Also, the examples of actual construction works are shown. (Kako, I.)