Developments in ground anchor technology: Carbon Fibre Reinforced Polymer (CFRP) Matthew Sentry, Abdelmalek Bouazza, Riadh Al-Mahaidi Department of Civil Engineering, Monash University, Clayton, VIC, Australia Len Carrigan, Darren Loidl Geotechnical Engineering, Tullamarine, VIC, Australia Keywords: Ground anchor, CFRP, FRP, carbon fibre, Fibre reinforced polymer ABSTRACT Anchored structures are one method of ground improvement used in practice. Steel strand ground anchor corrosion issues can restrict long term use of ground anchors. Advances in the development of corrosion resistant materials such as fibre reinforced polymer (FRP) including carbon fibre based reinforced polymer (CFRP) and aramid fibre based reinforced polymer (AFRP) have allowed for research into the development of a more robust anchor system that aims to eliminate the limitations currently encountered with steel strand ground anchors. This paper provides an overview of the development of ground anchors from alternative materials (CFRP and AFRP). 1 INTRODUCTION Ground anchors are a sub-structural member that transmit a tensile force from the main structure to the surrounding ground (Hanna, 1982). Ground anchors are used in a variety of civil engineering applications to stabilize rock/ soil faces and resist uplift and overturning forces acting on structures (Littlej ohn and Bruce, 1977, Weerasinghe and Adams, 1997, Xanthakos, 1991). Developments in new age materials such as aramid fibre and carbon fibre have enabled engineers to actively investigate ways of reducing limitations of the current steel strand ground anchors. This article provides an overview of current best practices for steel strand ground anchors and investigates the developments of fibre reinforced products emerging into the market that have potential to replace steel strand anchors. 2 GROUND ANCHORS 2.1 Background With the exception of the development of the single-bore-multi-strand ground anchor system developed by Tony Barley, ground anchor design has not changed dramatically since the works carried out by Littlejohn and Bruce (1977) and Hanna (1982). Recent research has focused on improvements to anchor corrosion protection. Global standards (IS/ BS EN 1537:2000) now require a minimum two levels of corrosion protection system be used for all permanent ground anchors. 2.2 Current ground anchor practices The publishing of works by Littlejohn and Bruce (1977) and others provided the foundations for the design methods used in current best practices. Since the development of the fundamental design methods numerous standards have been developed. Over the years these standards have been refined based on further work carried out by Hanna (1982), Habib (1989), Littlejohn and Bruce (1977), and Littlejohn and Weerasinghe (1997) to name a few. In the last 10 years the primary areas of anchor improvements have been advancements in installation process, minimisation of risks and hazards, and improvement of corrosion protection. This paper will discuss the advancements made with current corrosion protection systems. 2.2.1 Corrosion Protection System Corrosion occurs as a consequence of in-homogeneities or impurities in the steel, grout or by the existence of salts such as chlorides within the ground or grout mix (Littlejohn and Bruce, 1977). Permanent steel strand ground anchors require several areas to be corrosion protected, including tendon bond length, tendon free length, transition between anchor head and free length, and the anchor head.