Mechanisms of Improved Durability Properties in Concrete with Reclaimed Paint Addition

Abstract

Polymer-modified concrete has superior mechanical and durability properties, but it is expensive. Engineers and researchers attempt to achieve the same properties with cheaper alternatives. Superior durability properties, such as higher carbonation resistance, lower sorptivity, and lower drying shrinkage, can be achieved by incorporating reclaimed water-based paint (RWBP) in concrete. However, the mechanism by which the RWBP acts in concrete remains a mystery. Because concrete durability depends on capillarity, this study systematically investigated relevant behaviors and microstructures of RWBP-incorporating concrete, including open porosity, surface wettability, dynamic contact angle, and capillary absorption, supported by microstructural observations. Results show that RWBP addition reduced open porosity and increased pore tortuosity, thereby lowering capillary absorption rates. Surface wetting force also was mitigated by incorporating RWBP, reducing water penetration. Moreover, the formation of discontinuous paint films along pore walls obstructed transport pathways and contributed to reduced capillarity. These findings provide theoretical insights into RWBP’s role in concrete modification and demonstrate its practical potential for promoting cleaner and more sustainable reuse of paint waste in construction.