Testing methods for chemical prestressing and adaptation to GFRP rods

Chemical prestressing of FRP rods is emerging as an alternative solution for external prestressing of FRP rods with wedge anchors. One effective material in this approach is concrete with added Calcium Sulfoaluminate cement (CSA), which not only helps reduce the carbon footprint but also provides expansion characteristics similar to mechanical anchors. Prestressing by about 30% of ultimate capacity can be a solution to improve serviceability of glass fibre reinforcement bars (GFRP). GFRP with established durability tests and a proven serviceability limit of 100 years could be a potentially economical option. GFRP rebar with proved long term durability and bond strength tests can gain additional benefits from chemical prestressing without a damage to the FRP rebar end. CSA-enhanced concrete demonstrates a high level of residual strain, non-linearity, significant plastic deformation compared to conventional concrete. To evaluate these properties, the Standard Test Method for Restrained Expansion of shrinkage-compensating concrete proved to be the most effective. Initial expansive concrete studies proved that HPC mix achieved higher expansion than NSC mix.To monitor the expansion, a variety of measurement tools were employed, however these techniques will have to be repeated with HPC &CSA mix. To assess the effects of GFRP chemicaly prestressed structural elements, the right HPC & CSA balance and numerical analysis must be established.