SULFATE ATTACK IN CONCRETES EXPOSED TO COMBINED ACTION OF FLEXURAL LOAD AND DRY-WET CYCLING

摘要

Degradation of fly ash concrete (FAC), high performance concrete (HPC), and green high durable concrete (GHDC) subjected to combined action of flexural load, dry-wet cycling and sulfate attack is investigated. The sulfate used was 5% magnesium sulfate solution. Results show that dry-wet cycling accelerates the sulfate corrosion of concrete. The flexural load defers the corrosion in early stage, yet it accelerates the corrosion in the later stage of the process. And a superposition effect of dry-wet cycling and flexural load on the sulfate corrosion of concrete can be observed. In the initial corrosion stage, the degradation of concretes under multifactors (dry-wet cycling + magnesium sulfate + flexural load) is slower than that under doublefactors (dry-wet cycling + magnesium sulfate), however with the erosion process proceeds, the deterioration of concretes under multi-factors is worse than that under double-factors (dry-wet cycling + magnesium sulfate) or single magnesium sulfate. It is found that the deterioration of concretes subjected to combined action of dry-wet cycling and magnesium sulfate solution is most severe at the initial stage. GHDC shows better corrosion resistance and surface scaling resistance under multi-factors and double-factors, and HPC has the best property when subjected to single magnesium sulfate corrosion.