Abstract
Abstract This study investigates the effect of hydrothermal aging on the properties of glass fiber reinforced polymer (GFRP) rebars manufactured with isophthalic polyester or vinylester resin and glass fiber type E. The GFRP rebars were immersed in an alkaline solution (pH 12.6) for 1000 h at different temperatures (23 and 60 oC), and their deterioration was evaluated based on microstructural and chemical changes (using SEM, DSC, XRF, and FTIR techniques), moisture absorption, and variation in mechanical properties. The results indicated an increase in the presence of voids and water absorption of the rebars with accelerated aging, with a reduction in the glass transition temperature of the resin and alteration of the chemical composition of the glass fiber. The comparison between the experimental results indicates that the rebars with matrix in vinylester resin present greater chemical resistance than the rebars with a polyester matrix. The degradation of the rebar also resulted in a reduction of approximately 6% in the tensile strength of the rebar and 2% in the modulus of elasticity. Using the damage model, it was possible to identify that the reduction in mechanical strength was associated with the simultaneous degradation of the resin and glass fiber due to the alkaline attack.
Highlights
Reinforced concrete with steel rebars is the most widely used structural material for the construction of bridges, ports, viaducts, drainage systems, and building structures
For the vinylester glass fiber reinforced polymer (GFRP) rebar, a variation in the thickness of the resin covering in the range of 0–87 μm was observed, whereas, for the polyester GFRP rebar, this variation was in the range of 9–79 μm
GFRP rebars manufactured with two types of matrices, vinylester and polyester, were subjected to hydrothermal aging in an alkaline solution for 1000 h at 23 oC and 60 oC
Summary
Reinforced concrete with steel rebars is the most widely used structural material for the construction of bridges, ports, viaducts, drainage systems, and building structures. The cost of maintenance and recovery of reinforced concrete structures, associated with corrosion in steel reinforcements, is estimated to be approximately 3.5% of the Brazilian GDP1, which creates an economic problem. One of the alternatives to reduce such degradation is the replacement of steel rebars with glass fiber reinforced polymer (GFRP) rebars, mainly in major structures such as bridges, viaducts, and ports[2, 3], because the GFRP rebars have greater durability than steel rebars, high specific strength and stiffness combined with low specific weight[4]. GFRP rebars can be produced with different types of thermosetting resins (epoxy, polyester, or vinylester), and different types of glass fibers (E, ECR, or AR).
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