Evaluation of the sealing effectiveness of expansive cement grouts through a novel water penetration test

Abstract

The main objective of the work presented in this paper is to evaluate the effectiveness of using three inorganic expansive agents in developing expansive cementitious grouts for sealing concrete cracks. Two of the agents were ettringite-based (K and NK) and one was CaO-based (G). Nine expansive cement grouts and one non-expansive cement grout were developed, and their expansive and mechanical performance were characterized. Additionally, an original method based on the water penetration test is proposed to evaluate the sealing capability of the produced grouts which has demonstrated high feasibility in determining the sealing effectiveness of the cement grouts designed. After sealing the simulated cracks, a strong decrease (≈80%) of the water penetration was detected when using 5% in weight cements of G or NK agents. An important but lower decrease (≈50%) was detected by using 5% of K agent. Moreover, the results obtained in the Brazilian test indicated that sealing with expansive cement grouts allows a high integration of the sealing material within the surrounding concrete element, achieving good mechanical bonding, so the sealing material and concrete act as a compact sole material. BSEM-EDAX analyses also showed slight evidence of chemical interaction between the sealing expansive grout and the surrounding concrete when using NK agent, but strong evidence of physical interaction since the penetration of some kind of amorphous hydrates from the grout side to the concrete side was detected.