No abstract

No abstract

Abstract-The purpose of this study is to verify the effect of the new concept of admixture (early strength agent). Its admixture was developed to achieve rapid construction. Original use of the admixture is to improve the productivity of a concrete secondary product. However, since lining concrete to carry out the demolding a relatively small strength, the authors were judged to be able to exploit the characteristics of the admixture. Then, pursuing the possibility of realizing the shortening of the construction period, is applied to the tunnel construction by NATM, it was measured such as compression strength and air permeability coefficient as the physical properties of the hardened concrete. In this paper, we describe the results of a study regarding the possibility of improving the durability in addition to the improvement of productivity. As the result shows, it is possible for the concrete made with accelerator to get greater durability than the normal combination concrete after it was demold because concrete mixed accelerator showed large enough compressive strength.[1].