Bond Deterioration of GFRP Concrete Enhanced with Steel Fibers Subjected to External Sulfate Attack

Abstract

Concrete structures are exposed to sulfate and chloride attacks when are used in different environments such as seawater, deicing salts or industrial waste. Sulfate corrosion is considered one of the most important factors that responses for deterioration of construction materials performance. When sulfate attacks concrete, sulfate ions interact with cement materials to form chemical compounds inside the concrete. These compounds result volume increase and create internal stresses causing cracks, spalling and reduction in concrete strength. In this paper, the effect of external sulfate attack on properties of concrete samples enhanced with and without steel fibers (SF) and on bond damage between glass fibers reinforced polymer GFRP bar and concrete were investigated. Samples were completely immersed in 10% magnesium sulfate solution for two different exposure periods (60 & 120 days) to compare with control samples. Compressive and tensile strengths, density and pulse velocity were experimentally investigated. Push-out test was also carried out to study the damage in bond between concrete and GFRP rod. The results of concrete samples immersed in magnesium sulfate solution for 60 days showed an increase in compressive strength, tensile strength and density, while the results decreased for samples immersed for 120 days.