Crack sealing capacity in chloride-rich environments of mortars containing different cement substitutes and crystalline admixtures

Abstract

This paper presents the results of a preliminary study aimed at assessing the crack sealing capacity in chloride environments of different concrete mixtures, incorporating supplementary cementitious materials as well as self-healing enhancing crystalline admixtures. For each addition, also including pulverized fuel ash and silica fume, different contents were taken into consideration. Cylinder specimens were precracked in splitting up to three different crack-opening ranges, simulating different service conditions, and then exposed to different conditioning environments, also containing different concentrations of sodium chloride and including both permanent immersion and wet/dry cycles. Healing conditioning was performed up to three months and crack sealing was visually inspected and quantified via image analysis procedures, monthly. Optimum dosages of each cement substitute/addition were quantified, also considering, besides the healing capacity, also the fresh state performance and compressive strength development. The good performance of mixes with crystalline admixture even under open-air exposure, as well as of other investigated mixes with reference to crack openings and exposure conditions, paves the way to revise the significance of a serviceability design parameter such as the maximum allowable crack width as a function of the exposure with the concept of a sealable crack width.