GFRP Bar Used in Light Weight Concrete (LWC) Bridge Deck

Fiber Reinforced Polymer (FRP) composite material has good corrosion resistance and high tensile strength, which is an ideal material to be used as main reinforcement in reinforced concrete for the purpose of steel corrosion prevention. Among the current commercially available FRP products, i.e. carbon-FRP, glass-FRP, aramid-FRP, glass-FRP (GFRP) gains more interests to the civil infrastructure industry since it has lower cost as compared to the other ones.

GFRP bar is non-metallic material. It doesn’t corrode as the way steel does in reinforced concrete. However, this doesn’t mean GFRP bar is durable in a long-term view. The existence of concrete pore water with high pH values gives rise to the long-term durability problem for GFRP bar. Chemical reactions between hydroxide ions and resin matrix, and glass fibers as well,result in the materials degradation and loss of bond strength between fibers and resin matrices. Certain sustained loads acted on GFRP bar tend to induce GFRP micro-cracking, which provide passages for the ingress of hydroxide ions into the GFRP bar. The width of micro-cracks depends on the sustained stress level. In this regard, GFRP bar is expected to gained more strength loss under concrete pore water attack in combination with sustained loading as compared to that without sustained loading. 

Recently, a long-term performance prediction of GFRP bar in moist concrete beam indicated a significant strength loss of GFRP bar at elevated temperature exposure. In recognition of this, parametric studies were performed on GFRP bar Reinforced Normal Weight Concrete bridge deck to study the structural behavior and the real sustained stress level in GFRP bar under service loads. The results indicated that the design of GFRP RC deck is always controlled by the serviceability and the sustained stress in GFRP bar is in between 3.44-7.52% of GFRP design strength on the basis of ACI 440 design guideline and AASHTO LRFD Bridge Design Specification.

Lightweight structural concrete has unit weight approx. 90-120 lb/ft 3. By using LWC in GFRP bar reinforced concrete bridge deck is expected to give less sustained load effects on bridge deck, which could be a benefit to the long-term durability of GFRP bar since the sustained stress in GFRP reinforcement is lower than that in NWC deck. Therefore, it becomes essential to investigate the sustained stress in GFRP bar reinforced LWC bridge decks.

 

Purchasing Fiberglass Chopped Strand Mat, please focus on Sichuan Sincere & Long-term Complex Material Co., Ltd, and contact email: fred@chinaweibo.com.cn or chat on Skype: fred.wei08