A study of the long-term durability of glass fibre reinforced polymer (GFRP) soil nails

Abstract

A study durability of Glass Fibre Reinforced Polymer (GFRP) bar against chemical degradation has been carried out. The objective of the study is to determine whether GFRP bar can be a suitable material for permanent soil nail application. Accelerated aging test data in accordance with ASTM 7705 targeted to test the GFRP bar tensile strength under simulated alkaline and saline environmental conditions was provided by third party. The data was presented in the form of tables and graphs. The tensile resistance of both controlled and aging samples shows high variance and inconsistent degradation mechanism, violating the fundamental assumption of Arrhenius principle. The accelerated aging test data could not provide sufficient data to interpret the durability performance of GFRP bar and therefore the applicability of permanent GFRP soil nail. The test results from this experimental programme revealed that the inadequate guidance provided by the current ASTM 7705 test standard. Recommendations are proposed in this project to facilitate the improvement of the current accelerated aging test standard. The Load and Resistance Factor Design (LRFD) approach is proposed to introduce (i) an application specific factor ; and (ii) a composite specific resistance factor to cater for the GFRP bar variability in designing GFRP soil nail for both temporary and permanent application.