Durability of Pultruded GFRP Rebar Subjected to Natural Weathering in Alkaline Solution for 10 Years

Pultruded glass fibre reinforced polymer composite rebar is being considered as an alternate of the traditional material such as steel rebar in the construction industry because of its corrosion resistance property and longevity. In this work, long term mechanical, thermomechanical and chemical resistance properties of the GFRP rebar were investigated after being exposed in alkaline solution for 10 years in the natural weathering conditions. Micro-CT scans revealed that the rebar possessed very little porosity which increased but remained significantly low even after conditioning for 10 years. Low water absorption of the control and the conditioned rebars also supported the finding of small fraction of porosity content. Polymer matrix of the rebar was found to be softened due to plasticisation during conditioning in the alkaline solution as measured through its glass transition temperature (T g ); however, the ultimate T g was remained almost unchanged. Tensile strength and tensile modulus was found to retain up to 70 and 100%, respectively. Fibre/matrix de-bonding was the main tensile failure mechanism as observed through microscopic analysis. Elemental analysis of the conditioned rebar indicated that the compositions of fibre glass changed very little, which supported the greater retention of tensile modulus after conditioning for 10 years.