Research On Concrete Resistivity And The Damage Pattern Of Corroded Reinforced Concrete

The corrosion of rebars in reinforced concrete is an electro-chemical corrosion. Concrete resistivity has great influence on the corrosion rate of rebar. Damage pattern of corroded and cracked reinforced concrete is the base of assessment of corroded reinforce concrete, which has important value for the service life prediction of the reinforced concrete structure. In this paper, the influencing factors of the concrete resistivity and the damage pattern of corroded reinforced concrete are studied through tests. The research contents and results are as following:(1) Research on concrete resistivityInfluencing factors of concrete resistivity such as the quantity of cement per meter cube, water cement ratio, content of the fly-ash, fine slag powder and silicon ash are considered in tests. The RESI Resistivity Tester is used in tests, and the concrete resistivity under the two conditions is measured. According to the results, the quantity of cement per meter cube, water cement ratio, content of the fly-ash, fine slag powder and silicon ash all have important influence on concrete resistivity. The concrete resistivity is decreased as the increasement of water cement ratio, is increased as the increasement of the content of fly-ash, fine slag powder and silicon ash. Silicon ash has the most important influencing on concrete resistivity in the three mineral admixture. Less silicon ash can improve the concrete resistivity obviously. large content of fly-arch and fine slag powder can also increase the concrete resistivity.(2) Research on damage pattern of corroded reinforced concreteThree different water cement ratios, three different diameter of rebars, three different cover depth, fly-ash and wacker silicon powder are considered in the test. By electrical corrosion test, the appearance rule of oblique crack, vertical crack and the other cracks on the side surface of reinforced concrete specimens. One test specimens is broken and the rebars are obtained and measured when the width of longitudinal crack reachs 0.2mm,0.4mm,0.7mm, 1.0mm and 1.5mm respectively. A related expression between corrosion of rebar and width of longitudinal crack, cover depth, diameter of rebar and concrete strength is obtained, so a scientific basis is provided for the durability estimation and the reliability appraisal of concrete structures. These factors also have important influencing on the time crack happened, the speed of crack extension and the pattern of crack.