Susceptibility assessments of cement-based materials to external sulphate attack in Adana Basin

Cement-based materials are one of the basic building elements for modern society and every major construction project uses cement concrete in one form or another. However various detrimental processes and damaging agents either chemical and physical interactions adversely affect the mechanical strength of cement-based materials and their durability. Gypsum and gypsum-bearing units outcrops in northwestern part of the urban development areas of Adana city. In this study, water-soluble sulfate concentrations measured in the field were investigated on cement-based materials prepared in the laboratory with various sulfate solutions for one-year time. The samples were prepared based on EN 196-1 standard 4×4×16 cm for mass loss and length changes 4 cm3 for compressive strength, the powder samples were prepared for XRD analysis. Compressive strength reductions of up to 41% were measured in various solutions, especially in the combined solution of calcium sulfate and sulfuric acid. The length of some specimens submerged in sulfate solutions increased until 1.8 % and decreased to 3.5%. The mass of some samples immersed in sulfate solutions increased to 17% and decreased in others until it reached 0.7%. P-waves velocity showed that the samples contain high sulfate concentration had an increase in the speed of P-waves, reaching 0.26 m/s. SEM, EDS, and XRD analyses revealed that the minerals of thaumasite and ettringite resulting from the attack of different external sulfates are responsible for the deterioration of cement-based materials.