An Examination of How the Chemical Conditions of Concrete Surfaces is Impacted by the Presence of Flowing Water and Additional Materials

The design of underground structures necessitates meticulous consideration of the effects of groundwater flow and the contribution of supplementary cementitious materials (SCMs) on the chemical environment of construction materials. This study examined the leaching process of mortars under two conditions: stagnant water and flowing water, to understand how groundwater flow influences pH levels. By integrating the positive effects of supplementary materials and water flow on the concrete’s chemical environment, particularly pH, the goal is to mitigate the hazardous conditions surrounding concrete structures by utilizing the natural capabilities of bacteria. In an experimental setup, plain mortar prisms, as well as mortar with up to 35% replacements of ground granulated blast furnace slag (GGBS) and fly ash (FA), were tested. Each type of mortar included three prisms that were exposed to water flow using a digital hydraulic bench, which modified the surface chemical environment of the prisms. Additionally, three prisms of each mortar type were exposed to stagnant water conditions. The study found that water flow significantly affects leaching rates and the quantity of hydroxyl ions leached, leading to a reduction in pH in the solution. Furthermore, the incorporation of supplementary materials influences the chemical environment of the concrete, with a more pronounced effect observed in fresh concrete. Supplementary materials help reduce porosity, which is further enhanced by higher amounts of fly ash and GGBS. Specifically, it was noted that an increased amount of fly ash in concrete might result in reduced calcium ion release from the mortar.