Effects of Nanomaterials on Engineering Performance of a Potassium Methyl Siliconate–Based Sealer for Cementitious Composite

Currently, there is an urgent demand for more effective sealers to preserve the integrity and durability of concrete infrastructure in aggressive environments, such as bridge decks subjected to increasing traffic volume and increasing use of chloride-based deicers. To this end, this laboratory study explored the feasibility of employing graphene oxide and montmorillonite nanoclay to enhance the engineering performance of a penetrating sealer based on potassium methyl siliconate (PMS). The combined use of 0.15%-by-weight Na-montmorillonite nanoclay and 0.06%-by-weight graphene oxide in the PMS sealer resulted in the best performance, decreasing the water absorption and gas permeability coefficients. It also increased the water contact angle and viscosity, decreased the penetration depth of the PMS sealer, and reduced the scaling depth of mortar samples after freeze/thaw cycles. The improved protective performance of the nanomodified sealers can be attributed to the replacement of hydrophilic groups (─ OH) by hydrophobic groups (─ CH3) and changes in the micro-/nano-roughness of the sealed specimens induced by the admixed nanomaterials. In addition, thermogravimetric analysis confirmed the pozzolanic reaction between the nanoclay and the alkaline PMS sealer. Two empirical regression models were developed to quantify the relationship between the aforementioned performance parameters, which provided qualitative insights to guide the design and fabrication of nanomodified concrete sealers.