Engineering Performance of Sulfate-Bearing Soils in Iraq and Their Impact on Concrete Foundations: Mechanisms, Evaluation Methods, and Mitigation Approaches – A Critical Review

Abstract

In Iraq, which has a very wide distribution of sulfate-bearing soils, especially in the central and southern regions, these present a continuous issue for the concrete base’s durability and service life. Also, we see that in areas with elevated sulfate levels in the soil and groundwater, together with high temperatures, salinity, and the wetting and drying cycles, we get enhanced chemical and physical degradation. Into the concrete go the sulfate ions, which in turn react with the hydration products, mainly tricalcium aluminate and calcium hydroxide, to produce expansive compounds such as ettringite and gypsum. These reactions produce internal stresses, cracking, and long-term structural integrity issues. This review brings together available geological, geotechnical, and materials research to look at the spatial distribution and classification of sulfate soils in Iraq, the chemical and mechanical processes which underpin soil – concrete interaction, and what those issues mean for shallow, raft, and pile foundation systems. In this study,  both traditional and advanced evaluation techniques, which included chemical sulfate analysis, expansion testing, durability indices, and field-based non-destructive methods. Also, we went in-depth into mitigation approaches, which covered sulfate-resistant cements, supplementary cementitious materials, optimized mix design, soil stabilization, and protective barrier systems. This review also reports that present-day Iraqi engineering practices fall short in some areas, which in large part is a result of the low use of durability-based design frameworks and also the lack of in depth long term monitoring.