In this research, mechanism of generating microcracks in upper surface of concrete was investigated by experiments and numerical simulations. Based on the past researches, the authors assumed that generation of microcracks was promoted by waterproofing layer. As the results, it was found that microcracks were generated when moisture content of concrete is relatively high. Using waterproofing layer with permiable type primer, securing sufficient air content in concrete or polishing on upper surface of concerte were effective on mitigating microcracks. Furthermore, these cracks could be occurred only when thermal stress is increased in concrete, and vapor pressure is increased in micro pores, simulatenously.
