Prediction of time to crack initiation in reinforced concrete exposed to chloride

摘要

The effects of silica fume ratio and chloride concentration on reinforcement corrosion and crack time of concrete are investigated by accelerated corrosion test. In order to represent the situation that free chloride ions are present in the concrete ingredients in a reinforced concrete structure, solutions having various concentrations of Cl~- ions are used as mix water and 10 cm in diameter 20 cm in height cylindrical reinforced concrete samples are produced. During the accelerated corrosion test, the change of current density over time was recorded and the crack time of concrete was determined. After the test, the weight loss in the rebar and the free Cl~- amount in concrete around the rebar were determined. By using the test results, an equation for predicting the time to crack initiation of a structure because of corrosion damage is developed according to silica fume ratio, free Cl~- concentration and accelerating factor.