Thermal Properties and Heating and Cooling Durability of Reactor Shielding Concrete

Information is sought on some thermal properties of various concretes made of domestic raw materials for radiation shields of a power reactor and of a high-flux research reactor. The present paper briefly describes the results of measurements of thermal expansion coefficient, specific heat, thermal diffusivity, thermal conductivity, cyclical heating and cooling durability and further some considerations of relationship between the thermal properties and the durability together with several photographs of the concretes. In general, it is shown that the heating and cooling durability of such a concrete as has a large thermal expansion coefficient or a considerable difference between the thermal expansion of coarse aggregate and the one of cement mortar part or aggregates of lower strength is very poor. And the decreasing rates of bending strength and of dynamical modulus of elasticity and the residual elongation of the concrete tested have interesting relations with the modified thermal stress resistance factor containing a ratio of bending strength and thermal expansion coefficient and it seems that it depends on the conditions of heat transfer on the surface of the test piece and furthermore, in practice, of heat release in the concrete shield whether a controlling factor over the durability is thermal expansion coefficient or difference of the thermal expansions of the coarse aggregate and of the cement mortar part.