Optimal preparation and characterization of self-curing concrete containing internal superabsorbent polymer and external waterborne epoxy coating

Abstract

This study aimed to develop a novel type of self-curing concrete, that is, concrete specimens concurrently cured with a superabsorbent polymer (SAP) and waterborne epoxy coating (WEC). First, the flowability, mechanical properties, and durability performance of the SAP internally cured concrete were tested to optimize its material composition. Subsequently, a modified grey target decision-making method based on a range analysis and grey target decision model was adopted to optimize the application parameters of the WEC materials. Furthermore, the performance of concretes cured with separate or composite SAP-WEC materials was evaluated by measuring the compressive strength, flexural strength, and chloride permeability. Finally, scanning electron microscopy was used to characterize the surfaces, interfaces, and internal microstructures of the samples. The optimal comprehensive performance of the concrete was obtained when WEC materials with a stoichiometry of 5:25 were applied at a rate of 240 g/m2 with double-layer sprays. The self-curing concrete possessed good properties in terms of high compressive strength and chloride resistance, followed by the concrete cured with the WEC materials, and then the SAP internally cured concrete. The microstructural analysis results showed that the simultaneous application of internal SAP and external WEC materials is conducive to ensuring moisture retention in concrete, thereby improving the hydration reaction degree and strength development. This work can serve as a solid base for the efficient utilization of self-curing concrete in engineering.