INFLUENCE OF THE DEGREE OF PORE SATURATION ON THE RESISTIVITY OF CONCRETE AND THE CORROSION RATE OF STEEL REINFORCEMENT

Quantitative relations between the corrosion rate of reinforcements (i(corr)) and the degree of pore saturation (PS) and resistivity (rho) of mortars without Cl- and with 2% Cl-were obtained. The mortar specimens were cured in a water fog chamber before the final exposure at 50-degrees-C and 50% relative humidity (RH). The electrolyte supply was found to determine the mortar resistivity which varies over a wide range (5 x 10(3)-5 x 10(7) OMEGAcm) and this in turn influences the i(corr) of the reinforcements. There is a critical practical PS value (PS(cp)) that results in a mortar resistivity of 10(5) OMEGAcm, below which i(corr) values are too small to pose any durability problems. Below the PS(cp) value, the resistivity of the mortar prevents active state corrosion of reinforcements as effectively as passivating layers of steel in mortars without Cl-.