A critical review of the testing and benefits of permeability-reducing admixtures for use in concrete

Permeability-reducing admixtures (PRAs) are marketed as an option to improve the concrete durability and reduce water ingress in structures. Two categories of PRAs that have become more prominent recently are hydrophobic pore blockers and crystalline waterproofers. A literature review was performed to determine the composition, mechanism of action, test methods to indicate durability, and performance of PRAs in concrete, with focus on their use in infrastructure. The test methods for evaluating the performance of PRAs and their effects have varying degrees of frequency and standardization and there is a lack of consistency in the experimental methods used to evaluate PRAs based on the studies found in the literature; the dosage, water to cementitious ratio (w/cm), testing age, and mixture designs were variable. There remains a need for studies with both field and lab data to establish relationships between lab results and field performance to determine laboratory test method validity for PRAs.