A STRATIFIED-THEORETICAL CALCULATION MODEL OF CONCRETE UNDER EXTERNAL SULFATE ATTACK

This paper presents an integrated investigation of deterioration process of corroded concrete by experiments and theoretical model. First of all, the porosities of concrete samples with different corrosion periods were measured by the mercury intrusion porosimetry (MIP). Then the distribution of sulfate ions in the concrete was measured by the spectrophotometric method. Afterwards, the compressive strength were measured. The results indicated that the porosity and the compressive strength of concrete in water firstly increased and then progressively stabilized at a constant value due to the hydration of cement. However, those values of concrete soaked in 5wt.% Na2SO4 solution increased and then decreased, resulted from the combination of cement hydration and the corrosion of sulfate ions. Moreover, a Stratified-Theoretical calculation model was established with the input parameters of corrosion depth of sulfate ion, length of concrete specimen, strength of concrete immersed in water and in sulfate solution. At last, the corrosion resistance coefficient of corrosion layer was firstly put forward to evaluate the deterioration process of concrete with high effectiveness.