Influence of Pore Structure on Chloride Penetration in Cement Pastes Subject to Wetting-Drying Cycles

Abstract

Copious studies have discovered a phenomenon that a chloride concentration peak appears on the surface of concrete under cyclic drying-wetting environments. In such cases, the chloride diffusion coefficient (D) obtained through directly fitting the standard error function of Fick's second law is no longer accurate. e more reliable D obtained by the method proposed by Andrade is employed in this research to investigate the influence of pore structure on chloride penetration rate of pastes. e results show that both the effective coefficient (D eff ) and the apparent coefficient (D app ) increase with total porosity, the most probable pore size, and water absorption porosity, suggesting that the increase of the three pore structure parameters accelerates chloride penetration rate under cyclic wetting-drying condition. e increase of the three parameters makes more room available and eases the difficulty for salt solution to enter the matrix and thus leads to the augmentation of chloride transporting in matrix.

Complex Effect of Portland Cement Modified with Natural Zeolite and Ground Glass Mixture on Durability Properties of Concrete

“…The specimens are soaked in NaCl solution for 7 days before the start of the tests so that they are saturated with the solution, which enhances the destructive effect of the cold; consequently, we should see a significant improvement in the results when comparing the values of the specimens cured for 28 and 90 days. These results only confirm the observations of other authors that it is often very difficult to establish a direct correlation between porosity and conductivity parameters [28] and that the transport properties of cement-based composites depend not only on capillary porosity but also on other pore parameters, such as the connectivity and tortuosity of capillary pores [29].…”

Sumažinto cemento kiekio kompozitų su gamtinio ceolito ir stiklo atliekos priedu tyrimai

“…Tačiau verta pastebėti, kad vis daugiau atsiranda publikacijų (Chang et al, 2019;Shi et al, 2019), kuriose autoriai sutinka, kad chlorido jonų difuzijai įtakos turi bendras poringumas ir porų skersmuo, tačiau mano, kad pagrindinę įtaką šiam rodikliui turi cementinės matricos porų vingiuotumas ir jungiamumas. Autoriai (Shen & Chen, 2007) palaiko šią nuomonę ir teigia, kad vertinant poringumo poveikį chlorido jonų difuzijos koeficientui turi būti atsižvelgta į vingiuotumo parametrus.…”