A Study on Crack Prevention at Service State of Reinforced Concrete Member Fortified Tension Zone by Reactive Powder Composite
Isao UJIKE, Kazunori KATO, Yoshimitsu KONISHI and Masato NUMATA
Abstract:Cracks in concrete structure cause deterioration of durability due to corrosion of reinforcement. Although crack width is controlled in less than the allowable value in the present design method, concrete structure with cracks deteriorate more easily than that without cracks. The objective of this study is to develop the reinforced concrete member that a crack doesn't occur in serviceability limit state. This study gave attention to a super high strength of Reactive Powder Composite iRPCj, especially a high tensile strength on crack development. RPC consists of premixed powder in selected combination of cement, silica particles, siliceous sand, special water reducing agent, and steel fibers. A part of tension zone in reinforced concrete beam was fortified by RPC. The cross-sectional area of RPC part was varied in three ways. Flexural load tests of beam were carried out. The crack development moment of the beams fortified by RPC increased with the increase of reinforcing area of RPC. When the bending moment that the cracks with permissible crack width for corrosion of reinforcement develop in the usual reinforced concrete beam acted, cracks didn't occur in the beams reinforced with RPC suitably. The flexural behaviours of the beam reinforced with RPC could be analysed by elastic theory in the range of service state. When the bending moment on the occurrence of the crack is estimated, the restraint stress due to autogeneous shrinkage of RPC must be taken into consideration. Key Words:Cracks, Reactive powder composite, Serviceability limit state, Flexural member, Elastic analysis, Autogeneous shrinkage, Durability