Durability of GFRP bars: a critical review of the literature

Abstract

The research undertaken during the last two decades has shown that one of the potential solutions to the steel-corrosion-related problems in concrete is the use of fiber-reinforced composite (FRP) reinforcement as a replacement for traditional steel bars. Glass FRP (GFRP) reinforcement is gaining more popularity in construction of bridges and in other concrete structures because of its low cost compared to Carbon FRP reinforcement. The durability of these materials, especially under severe environmental conditions, is now recognized as the most critical topic of research. The lack of data on durability of the GFRP reinforcements is a major obstacle to their acceptance on a broader scale in civil engineering. This paper summarizes the most significant research work published on the durability of FRP bars in the past two decades. A comprehensive review of the literature on the durability of FRP bars indicates a significant increase in the number of studies in this area in the last decade. The durability tests conducted by the authors and others on the latest generation of GFRP bars subjected to stresses higher than the design limits, combined with aggressive mediums at elevated temperatures, have concluded that the strength reduction factors adopted by current codes and guidelines are conservative. These factors were based on limited test results that were carried out on the early generations of the GFRP products, which have now substantially changed.

Structural evolution of glass surface during alteration: Application to nuclear waste glasses

“…However, experience plans show a complex chemical dependence of glass dissolution rates. For instance, Zr increases glass resistance, not only to neutral water but also to alkalis, a property developed in alkali-resistant glasses [2]. Such alkaliresistance is enhanced for Zr concentrations larger than 15 wt.% and enables these glasses be used to reinforce cementitious and other alkaline matrices [3].…”

Structural role of ZrO2 and its impact on properties of boroaluminosilicate nuclear waste glasses

“…38,39 ZrO 2 has been reported to enhance the chemical durability of glasses not only in neutral pH condition but also in alkali-rich environments. [38][39][40] However, even though the initial dissolution rate drops significantly with increasing ZrO 2 concentration (up to 8 mol%) in soda-lime borosilicate glasses, recent findings showed that the inhibiting effect of ZrO 2 on the dynamics of alteration layer formation ultimately results in a greater degree of corrosion in the long term. [41][42][43] Zirconium ions were found to be mostly six-fold coordinated and [ZrO 6 ] octohedra link with other network formers such as [SiO 4 ] tetrahedra through corner-sharing.…”

Fibre-Reinforced Polymer (FRP) Composites

“…However, several studies have shown that the mechanical properties of FRP bars can be considerably affected when they are subjected to moisture, alkaline, acid or saline solutions [52]. Unlike steel bars, FRP bars are susceptible to creep rupture under constant loads.…”