Role of Cement Alkali Content in Acid Attack: A Pore‐Solution and Pore‐Size‐Distribution Study

The behavior of hydrated portland cement pastes in an acid-buffered solution of acetic acid/sodium acetate (HAc/ NaAc) (pH 4.5) during a period of 90 days at a temperature of 21°C has been studied. The changes that were caused by the acid ingress were monitored via analysis of the extracted pore solution. The evolution of the porosity and pore-size-distribution changes were evaluated by using intrusion mercury porosimetry, and those of crystalline compounds were evaluated by using X-ray diffractometry. A similar study was conducted with an equivalent series of samples that were immersed in distilled water. The results showed the important role that cement alkali content (1.03% K 2 O, 0.2% Na 2 O) has in the mechanism of the acid attack. Interesting correlations were established between pore-solution and porosity data.