EXPERIMENTAL RESEARCH ON COMPRESSIVE STRENGTH OF CONCRETE DAMAGED BY COUPLING OF CHLORINE-CORROSION

Accelerated corrosion testing on concrete specimens was carried out under the action of dry-wet cycle and constant-current power with using the mass fraction of 5% NaCl solution to investigate the degradation law of mechanical properties of concrete in chloride environment. The concrete specimens damaged by chloride erosion and coupling of chlorine-rebar corrosion were obtained, and then the compressive strength of concrete specimens was studied. The results showed that under the action of single factor for chloride erosion, the compressive strength of concrete increased first and then decreased with the increase of time of dry-wet cycle, with a maximum increase of 16.6%; under chlorine-rebar corrosion coupling, the compressive strength of concrete generally decreased with the corrosion rate of reinforcement increases, and the decrease in the early stage was faster than that in the later stage. When the corrosion rate reached 6.3%, the compressive strength was 19.4% lower than the initial undamaged strength; when the corrosion rate reached 14.9%, the compressive strength of concrete decreased by 24.5%. Corrosion damage was the main reason of the decrease of concrete strength, the corrosion rate and the corrosion-induced crack width were selected as the strength damage variables respectively to analyze regressively the test data, and consequently established the calculation models on compressive strength deterioration of concrete damaged by chlorine-corrosion coupling.