Effectiveness of waterproofing methods and commercial chemicals against carbonation and transport properties after carbonation

Abstract

With growing interest in low-clinker binders and the need to protect structures from water-induced degradation, assessing the performance of waterproofing chemicals under naturally carbonating conditions is essential. This study evaluates twelve commercial products across three waterproofing strategies: integral admixtures, hydrophobic impregnations, and surface coatings, applied to mortars made with ordinary Portland cement (OPC) and four low-clinker binder blends (fly ash, slag, limestone, and calcined clay). After accelerated carbonation, treated and control specimens were tested for water absorption and oxygen permeability, two parameters critical to corrosion in carbonated environments. Results show that crystalline admixtures and hydrophobic impregnations effectively reduced carbonation depth and moisture transport, particularly at lower w/b ratios. Additionally, integral hydrophobic treatments enhanced water absorption resistance but simultaneously increased oxygen permeability relative to the control. In contrast, the crystalline cementitious coatings were largely ineffective, offering little resistance to carbonation and even raising oxygen permeability. Overall, while most treatments in low-clinker systems could not outperform control OPC in carbonation resistance (except one hydrophobic impregnation), several significantly lowered moisture transport to levels below OPC, highlighting their potential for durability enhancement.