Review of Potential Mitigation Methodologies for Existing Concrete Structures Containing Pyrrhotite-Bearing Aggregates

Deterioration of concrete foundations due to pyrrhotite oxidation has led to several studies to better understand its reaction mechanisms, develop methodologies to identify potentially reactive aggregates, and quantify the influence of mixture formulations on potential pyrrhotite oxidation. However, little research has evaluated the potential of sealants that mitigate oxidation of existing foundations known to include pyrrhotite-bearing aggregate that has yet to cause severe deterioration. This paper provides a comprehensive review regarding the potential use of mitigating sealants from three perspectives. First, a general overview of pyrrhotite reaction mechanisms and associated damage in concrete structures is provided. Second, mitigating sealants commonly used to mitigate deleterious reactions in concrete substrates are summarized, and their potential efficacy for mitigating pyrrhotite is discussed. Last, a brief overview of established methodologies for evaluating moisture and gas transport properties of concrete is provided from the perspective of quantifying sealant performance and their potential to be used within a performance-based framework. The findings of this review are envisioned to guide future research efforts toward recommending potential mitigation strategies for existing structures known to contain pyrrhotite-bearing aggregate.