Glass Fiber Reinforced Polymer Rebars Research Articles

Analytical and Experimental Behaviour of GFRP-Reinforced Concrete Columns under Fire Loading

Fire engineering endeavours to mitigate injury or the loss of life in the event of a fire. This is achieved primarily through fire prevention, containment, and extinguishment measures. Should prevention fail, the structural integrity of buildings, coupled with effective evacuation strategies, becomes paramount. While glass fibre-reinforced polymer (GFRP) materials have demonstrated efficacy in reinforcing concrete elements, their performance under fire conditions, notably in comparison to steel, necessitates a deeper understanding for structural applications. This study experimentally and numerically investigates the fire performance of GFRP-reinforced concrete (RC) columns subjected to only fire load without additional external loads. The research aims to ascertain the fire resistance based on the thickness of the concrete coating and the ultimate tensile strength of GFRP rebars after 90 min of fire exposure. Four GFRP-RC columns were subjected to a standardized fire curve on all sides in the experimental program. In the analytical program, a theoretical model was developed using the heat transfer module of the COMSOL software. The results of both analyses were very close, indicating the reliability of the procedure used. Based on the findings, recommendations regarding the fire resistance of GFRP-RC columns were formulated for structural applications. Results from this research provide the civil engineering community with data that will help them continue using FRP materials as internal reinforcement for concrete.

Experimental study on seismic performance of squat RC shear walls reinforced with hybrid steel and GFRP rebars

This laboratory study investigates the effect of using steel and glass fiber reinforced polymer (GFRP) rebars in shear walls with aspect ratios less than two. The study evaluates six full-scale shear walls subjected to constant axial load and cyclic lateral loading, with aspect ratios of 1.08 and 1.75. The aim is to analyze how the use of steel and GFRP rebars affects crack patterns, fracture, seismic performance, dissipated energy, and ductility of shear walls. The six specimens consist of two reference ones (SRC1 and SRC2) reinforced with steel rebars, two specimens (GRC1 and GRC2) reinforced with GFRP rebars, and two specimens (S-GRC1 and S-GRC2) reinforced with a hybrid of steel and GFRP rebars. The conclusions drawn suggest that employing a hybrid combination of steel and GFRP rebars resulted in a notable alteration of crack propagation behavior and failure mode, transitioning from flexural compression to flexural tension. Additionally, compared to the specimens reinforced solely with GFRP rebars, there was an observed expansion of the hysteresis curve. Additionally, parameters such as cumulative dissipated energy, ductility, and load modification factor based on ductility increased in the S-GRC1 and S-GRC2 specimens compared to the GRC1 and GRC2.

Comparative Life-Cycle Assessment of Steel and GFRP Rebars for Procurement Sustainability in the Construction Industry

This research examines the potential impact on the procurement sustainability of replacing steel rebars with Glass Fiber-Reinforced Polymer (GFRP) rebars in the construction industry, focusing on screed pre-cast hollow core topping in a project in the Kingdom of Saudi Arabia. A comparative life cycle assessment (LCA) is conducted using One Click LCA (Version 0.26.0) software for cradle-to-grave analysis. The assessment covers various stages, including raw material extraction, manufacturing, transportation, usage, and recycling. The comprehensive LCA highlights GFRP rebars as a more sustainable alternative to steel, emitting 17% less CO2 equivalent (2e) per kilogram throughout its life cycle. Additionally, GFRP requires substantially less mass compared to steel, resulting in a dramatic reduction in CO2e emissions ranging from 77.89% to 85.26% across different spacing configurations in real-world construction scenarios, as presented in this research case study. These findings suggest that GFRP rebars offer a promising solution for reducing the environmental impact of construction activities while potentially yielding significant cost savings over the project’s life cycle. Integrating environmental considerations into material selection processes can prioritize sustainability without compromising performance or safety, contributing to a more sustainable future for the construction industry globally.

Fatigue life and behaviour of ribbed GFRP reinforced concrete beams

Despite the growing adoption of glass-fibre reinforced polymer (GFRP) as an alternative to steel reinforcement, there is limited research addressing the fatigue performance of GFRP bars in reinforced concrete structures. Existing literature presents contradictory experimental data and conclusions regarding the fatigue behaviour of GFRP rebars embedded in concrete. This study investigates the fatigue life of ribbed GFRP bars embedded in concrete beams through an experimental program, considering factors such as concrete strength and fatigue stress levels. Additionally, it introduces a testing protocol utilizing a displacement-controlled scheme to conduct fatigue testing, addressing many issues associated with force-controlled fatigue testing. Furthermore, the paper discusses cracking behaviour, deflection, and slippage, providing insights into the interaction between GFRP rebars and concrete under fatigue loading. The results of this study demonstrated that ribbed GFRP bars can withstand 2 million cycles of fatigue loading at a 40% stress ratio. The obtained fatigue life exceeds findings in existing literature, emphasizing the impact of stress ratio and bar surface profile on fatigue performance.

Feasibility Study of using Glass Fiber Reinforced Polymer rebars as Reinforcement in Concrete

Feasibility Study of using Glass Fiber Reinforced Polymer rebars as Reinforcement in Concrete

Enhancing Flexural Strength of RC Beams with Different Steel–Glass Fiber-Reinforced Polymer Composite Laminate Configurations: Experimental and Analytical Approach

This study intended to measure the efficiency of different strengthening techniques to advance the flexural characteristics of reinforced concrete (RC) beams using glass fiber-reinforced polymer (GFRP) laminates, including externally bonded reinforcement (EBR), externally bonded reinforcement on grooves (EBROG), externally bonded reinforcement in grooves (EBRIG), and the near-surface mounted (NSM) system. A new NSM technique was also established using an anchorage rebar. Then, the effect of the NSM method with and without externally strengthening GFRP laminates was studied. Twelve RC beams (150 × 200 × 1500 mm) were manufactured and examined under a bending system. One specimen was designated as the control with no GFRP laminate. To perform the NSM method, both steel and GFRP rebars were used. In the experiments, capability, as well as the deformation and ductileness of specimens, were evaluated, and a comparison was made between the experimental consequences and existing standards. Finally, a new regression was generated to predict the final resistance of RC beams bound with various retrofitting techniques. The findings exhibited that the NSM technique, besides preserving the strengthening materials, could enhance the load-bearing capacity and ductileness of RC beams up to 42.3% more than the EBR, EBROG, and EBRIG performances.

Structural Behavior of Circular Concrete Columns Reinforced with Longitudinal GFRP Rebars under Axial Load

This paper presents experimental and theoretical assessments of the structural behavior of circular steel fiber-reinforced concrete (SFRC) columns reinforced with glass fiber-reinforced polymer (GFRP) bars subjected to a concentric axial compressive load. Laboratory experiments were planned to evaluate and compare the effect of different design parameters on the structural behavior of column specimens based on experiments and finite element (FE) analysis. The experimental variables were (i) concrete types, i.e., conventional concrete (CC) and fiber-reinforced concrete (FC), (ii) longitudinal reinforcement types, i.e., steel and GFRP bars, and (iii) transverse rebar configurations, i.e., tied and spiral with different pitches. Sixteen column specimens were fabricated and categorized into four groups with respect to rebar configurations and concrete types. The results showed that the failure modes and cracking patterns of those four column groups were comparable, particularly in the pre-peak branches of load-deflection curves. Even though the average ultimate load of the columns with longitudinal GFRP bars was 17.9% less than that with longitudinal steel bars, the ductility index (DI) was 10.2% greater than their counterpart on average. The addition of steel fibers (SF) to concrete increased the axial peak load by up to 3.1% and the DI by up to 6.6% compared to their counterpart CC columns without SFs. The DI of specimens was increased by higher volumetric ratios (up to 12%) and spiral types (up to 5.5%). The concrete damage plastic (CDP) model for FC columns was updated in the finite element software ABAQUS 6.14. Finally, a new simple equation was theoretically proposed to predict the axial capacity of specimens by considering the inclusion of longitudinal GFRP rebars, volumetric ratio, and steel spiral/hoop ties. Good agreement between the proposed model predictions and the experimental/numerical results was observed.

Enhancing performance of concrete with glass fiber-reinforced polymer short rebars as coarse aggregates by confinement

Cutting glass fiber-reinforced polymer (GFRP) waste into aggregate-size reinforcing bars (short rebars) as coarse aggregates in concrete shows to be an effective approach for recycling waste GFRP composites. The resulting concrete with such short rebars however exhibits a reduction in the compressive strength comparing to the corresponding normal concrete, making it unable to be directly used for structural elements. The concept of using the confining jacket is therefore employed for such concrete to improve its compressive strength and toughness and to be used in structural elements. A total of 48 cylindrical specimens were prepared and tested under axial compression with the replacement ratio of coarse aggregates by the GFRP short rebars and the stiffness of the confining jacket as the two test parameters. The test results indicate that incorporating short GFRP rebars results in a reduction in compressive performance by up to 57.2%, and the use of CFRP jacketing significantly enhances the performance of the concrete with or without GFRP short rebars. Such enhancement tends to be more significant when the stiffness of the confining jackets or the replacement ratio increases. The reduction in the compressive strength due to the incorporation of 25% recycled GFRP short rebars is from 57.2% to 30.7%, when the number of layers of the confining CFRP jacket increases from 0 to 3 piles. Comparisons were made between the test results and the predictions from two widely-used stress-strain models for confined concrete, showing that both models overestimate the ultimate axial strain and Teng et al.'s model generally produces the compressive strength slightly higher than the corresponding test results as well as the predictions from Jiang and Teng's model.

Experimental investigation of flexural bond behavior of sand-coated GFRP rebar embedded in concrete

Steel rebars used in Reinforced Concrete (RC) elements may be subjected to corrosion due to aggressive environmental conditions. Rebar corrosion reduces the durability and the structural capacity of RC elements. On the other hand, since the steel rebars affect the magnetic fields, it is not preferred to be used in RC structures which is used to carry the equipment that propagate magnetic waves such as toll plazas on highways. For these reasons, the use of Fiber Reinforced Polymer (FRP) rebars is increasing, especially in RC infrastructure constructions. The objective of the present study is to investigate the bond behavior of Glass Fiber Reinforced Polymer (GFRP) rebar with a sand-coated outer surface in concrete using the arched beam test method. The concrete strength and the embedment length were chosen as variable parameters and 34 beam test specimens were tested in the laboratory. A comparative analysis of the crack patterns, the diagonal crack angles and the failure modes of the specimens is made. In addition, the experimentally determined bond-slip relationships were compared with different analytical models in the literature. Consequently, a bond-slip model, which takes into account CMR (Cosenza-Manfredi-Realfonzo) for the increasing part and mBPE (modified Bertero-Popov-Eligehausen) for the decreasing part, is proposed to be used in the numerical models of RC beams with sand-coated GFRP rebars. A prediction model for the bond strength is proposed, along with a recommendation for an upper bound value for the bond stress, which indirectly offers a minimum embedment length for a bond without slippage.

Lap splice assessment of GFRP rebars in reinforced concrete beams under flexure

To increase the knowledge and experience gained from the existing literature regarding the bond behavior of glass fiber-reinforced polymer (GFRP) rebars, a total of sixteen full-scale GFRP-reinforced concrete beams were subjected to a four-point bending test. The GFRP reinforcement comprised a single M16 (No.5) GFRP sand-coated bar without confinement reinforcement in the constant moment region. The research parameters encompassed three different lap-spliced lengths (i.e., 40-, 60- and 80-db) and two distinct concrete clear covers (i.e., 19 mm and 38 mm) to assess their impact on bond strength and failure modes. Strain gauges along the GFRP rebar and small potentiometers positioned at the end of the splice within the constant moment zone allowed detailed measurements. Rebar slippage in lap-spliced specimens was observed to have a limited impact on bond stress transfer capacity and member flexural stiffness until reaching maximum slippage. Concrete cover significantly influenced the behavior of lap-spliced GFRP-RC beams, with 38 mm-cc specimens exhibiting an average 21% higher capacity compared to 19 mm-cc specimens. The ACI expression exhibited an average overestimation of 24% for 19 mm-cc specimens, whereas for 38 mm-cc specimens, it offered a more accurate estimation, with only a 10% over-prediction. However, the computed lap splice length to achieve the required tensile stress was reduced from the one required by ACI due to extra factors implemented in the development length equation. This aligns with prior research findings that identified unconservative values of bond stress when employing the ACI provisions for specific combinations of parameters, highlighting the necessity for refinements in predictive models.

Reusing Egyptian in-situ construction &demolition waste(CDW)to produce sustainable concrete.Investigation of compressive &bond strengths using steel & glass fiber reinforced polymer(GFRP)rebars

ABSTRACT This research paper presents the effect of using recycled concrete aggregate (RCA), from the Egyptian construction waste, in different proportions on the bond performance between concrete and its internal reinforcement, where two types of reinforcement were used: a- steel reinforcing bars, and b- glass fiber reinforced polymer (GFRP) bars. 72 samples of concrete were prepared and tested with replacement ratios for natural aggregate (NA) with RCA: 0, 20, 40, 60, 80, and 100 %. The samples were divided into 150 mm cubes to conduct axial compression tests, and pull-out samples to investigate the effect of replacement ratios on the bond between concrete with steel and GFRP rebars. Results showed that concrete loses 26% of its compressive strength after replacing NA with 100% RCA. The results of the pull-out test for steel samples showed 30% higher bonding than GFRP samples. A slight decrease in bond was observed between the control and the tested samples, where the steel and GFRP samples showed a decrease of 5% and 9%, respectively, over the control samples for each, at a replacement percentage of 100%. It was also clear that the steel reinforcement bars had a stronger bond with the concrete, and this can be attributed to the stronger mechanical interlocking of the steel ribs than their counterparts in the GFRP. Failure patterns showed the crushing of concrete with steel bars, in contrast to the GFRP bars, which showed slipping from within the concrete with failure of the ribs in many samples.

Flexural behavior of concrete beams hybrid-reinforced with glass fiber-reinforced polymer, carbon fiber-reinforced polymer, and steel rebars

The utilization of fiber-reinforced polymer (FRP) reinforcements in structural design is increasing due to their non-corrosive nature. However, the anisotropic features and linear elastic behavior of FRP rebars have led researchers to explore the use of hybrid combinations of FRP and steel reinforcements. Current codes and guidelines predominantly focus on the design of glass FRP (GFRP) reinforced structural elements, leaving a gap in incorporating the hybrid use of FRP-steel combinations and different types of FRP materials, such as carbon FRP (CFRP). This study conducted experimental investigations on concrete beams reinforced with GFRP, CFRP, and hybrid (GFRP-steel and CFRP-steel in combination) rebars, comparing the results with theoretical models. Ten full-scale beams were tested under monotonic loading. Test results revealed that existing codes overestimate GFRP reinforced beam displacements while underestimating CFRP reinforced beam displacements. A reduction factor is proposed for the effective moment of inertia expression given by ACI 440.11-22 to predict the deflections of CFRP reinforced and hybrid reinforced beams. The experimental data for CFRP and hybrid reinforced concrete beams align well with the predictions calculated using the proposed equations.

Effect of sand coating on durability and micro-structural deterioration of GFRP rebar under alkaline environment attack

The objective of this study is to investigate the consequences of the sand-coated layer on the durability of glass fiber reinforced polymer (GFRP) rebars under four alkali solution concentrations and three temperatures. A total of 464 GFRP rebars specimens were manufactured to undergo accelerated corrosion experiments and mechanical performance test. Among them, 438 specimens were used to test the residual tensile strength of GFRP rebars after 120 days of immersion; 26 specimens were applied for surface observation and microscopic testing to analyze the degradation and damage process of GFRP rebars. SEM and digital camera were used to examine the micro-structure of samples either with or without sand layer covering. The unidirectional tensile strength experiment was conducted to test the remaining tensile strength of GFRP rebars after corrosion. The experimental results indicate that sand coating provides better protection and restraint in GFRP rebar durability reduction, resulting in a lower rate of fiber loosening and resin cracking and flaking when exposed to a solution over a pH of 12.5. As the failure of GFRP rebars ranges from local damage to cracking of the peripheral sand protective layer, the pH value of 12.5 is considered a critical alkali solution concentration. Based on experimental results, an improved model was proposed to predict the short-term and long-term residual strength values of GFRP rebars. The calculation results indicate that the predict values are in good agreement with the experimental ones, and the proposed model can be used to predict the residual strength of GFRP rebars.

On the Factors That Determine the Bond Behaviour of GFRP Bars to Concrete: An Experimental Investigation

It is becoming accepted that glass-fibre-reinforced polymer (GFRP) is a credible and effective replacement for steel in reinforced concrete (RC) to meet structural requirements whilst addressing durability concerns posed by steel over the long term. A better understanding of the bond behaviour between GFRP and concrete is essential for reliably and efficiently designing concrete structures with reinforced GFRP bars. This paper presents a parametric study of the bond behaviour of GFRP bars to concrete where the effects of the length, diameter, concrete strength, concrete cover thickness and rebar surface morphology of GFRP bars were investigated via a series of pull-out tests. The test results indicate that the bond strength of GFRP bars is predominantly influenced by their surface morphology, embedment length and diameter. On the other hand, the effects of concrete strength and cover thickness appear to have a limited impact on the bond strengths of GFRP rebars to concrete. It is shown that ribbed GFRP bars exhibit the highest bond energy of 89.4 Nmm and an average bond strength of 11.9 MPa. Moreover, the analysis of failure modes indicated the unique effect of GFRP surface morphology on failure mode. It is shown that 100% of ribbed GFRP failed due to concrete split, while 85% of sand-coated bars experienced failure due to bar slip. This examination of failure modes and their corresponding bond strengths provides a unique perspective on the bond behaviour between GFRP bars and concrete.

Axial bearing capacity and ductility of seawater sea sand coral aggregate concrete (SSCC) columns reinforced with hybrid GFRP and corrosion resistant rebars

The shortage of fresh water and river sand resources and steel corrosion are becoming increasingly prominent in engineering construction. Seawater sea sand coral aggregate concrete (SSCC) and corrosion resistant reinforcement are promising materials in replacement of conventional concrete and steel in building structures in island and reef construction. This study investigated the axial compression performance of GFRP (glass fiber reinforced polymer) and corrosion resistant rebars hybrid reinforced seawater sea sand coral aggregate concrete columns. A total of eighteen short columns were tested for axial compression performance, including three reinforcement ratios (1.01%, 1.56%, 2.26%) and 5 reinforcement types (pure GFRP reinforcement or G, pure stainless steel reinforcement or S, pure epoxy coated steel rebar (ECSB) reinforcement or E, GFRP-stainless steel reinforcement or GS and GFRP-ECSB or GE). The failure modes of the column are recorded and analyzed, and the axial bearing capacity and ductility are calculated and analyzed. Results show that the bearing capacity of columns is positively correlated with the reinforcement ratio. Generally, the bearing capacity of S-SSCC column and E-SSCC column are not significant different, but both are larger than that of G-SSCC column. The bearing capacity of hybrid reinforcement GS-SSCC and GE-SSCC column is between S-SSCC column and G-SSCC column. Meanwhile, it indicates that the theoretical calculation results of bearing capacity agree well with the experimental results. The ductility analytical results exhibit that the studied column specimens have the highest ductility when the reinforcement ratio is 1.56%. Among different reinforcement types, the ductility of G-SSCC is the smallest and the GE-SSCC and GS-SSCC column show improved ductility compared with G-SSCC columns.

Analysis of the bond behavior of a GFRP rebar in concrete by in-situ 3D imaging test

Computed tomography combined with mechanical tests offers completely new insight into the behavior of concrete samples under stress. Particularly the development of new fiber reinforcement materials for concrete elements requires appropriate material models and thus for investigating the interior of the concrete structure. In 3D image data obtained by computed tomography, local structural changes within the sample due to mechanical loading can be observed without further altering the sample. We applied this state-of-the-art approach to a concrete core with an embedded glass fiber reinforced polymer rebar under increasing forces applied to pull out the rebar. In this paper, authors describe a novel in-situ setup for non-destructively 3D imaging during the pull-out test. Conducting the pull-out test leads to the formation of local pore volume changes along the rebar. These pore volume changes are not only visualized but quantified analytically based on the images. Interpreting these volume changes, we derive a novel method for calculating strain and normal stresses in the rebar. Our new method captures the detailed distribution of the bond stresses between rebar and concrete and consequently describes the bond behavior more accurate. It turns out that the observed bond behavior cannot be explained completely by commonly assumed material laws. This emphasizes the need for further, more extensive research combining 3D imaging, mechanical testing, and quantitative image analysis.

Behavior of non-prismatic RC beams with conventional steel and green GFRP rebars for sustainable infrastructure

This study presents an experimental and finite element analysis of reinforced concrete beams with solid, hollow, prismatic, or non-prismatic sections. In the first part, a total of six beams were tested under four-point monotonic bending. The test matrix was designed to provide a comparison of structural behavior between prismatic solid and hollow section beams, prismatic solid and non-prismatic solid section beams, and prismatic hollow and non-prismatic hollow section beams. The intensity of shear was maximum in the case of prismatic section beams. The inclusion of a tapered section lowered the demand for shear. In the second part, Nonlinear Finite Element Modeling was performed by using ATENA. The adopted modeling strategy resulted in close agreement with experimental crack patterns at ultimate failure. However, the ultimate failure loads predicted by nonlinear modeling were generally higher than their corresponding experimental results. Whereas in the last part, the developed models were further extended to investigate the effect of the strength of concrete and ratio of longitudinal steel bars on the ultimate load-carrying capacity and cracking behavior of the reinforced concrete beams with solid, hollow, prismatic, or non-prismatic sections. The ultimate loads for each beam predicted by the model were found to be in close agreement with experimental results. Nonlinear modeling was further extended to assess the effects of concrete strength and longitudinal reinforcement ratio on failure patterns and ultimate loads. The parametric study involved beams reinforced with glass fiber-reinforced polymer (GFRP) bars against shear and flexural failure. In terms of ultimate load capacities, diagonal cracking, and flexural cracking, beams strengthened with GFRP bars demonstrated comparable performance to the beams strengthened with steel bars.

Strengthening of RC columns under eccentric loads using NSM steel and GFRP bars

The behavior of eccentrically loaded RC columns strengthened by NSM steel and glass fiber reinforced polymer (GFRP) rebars is investigated in this study. A total of six RC column specimens have been cast in this study with dimensions of (150×150×1200) mm (width × height × length). Two column specimens are unstrengthened and considered as controls, while the other specimens are strengthened by the NSM method using steel bars and hybrid steel and GFRP rebars. All column specimens have been tested under concentric and eccentric loads with an eccentricity of 75mm up to failure. Experimental results in terms of crack patterns, modes of failure, and load-displacement curves are all monitored, recorded, and assessed. The experimental results have shown an improvement in the ultimate load capacity for all strengthened column specimens. Further, results have demonstrated that, under concentric load, the almost similar enhancement in the strength of NSM-strengthened RC column specimens using steel bars only and hybrid steel and GFRP bars. However, at eccentric load, the ultimate load capacity of the strengthened RC column was increased by 62% and 79.45% compared to the control column using NSM steel and hybrid steel, and GFRP, respectively. Finally, this study found that at e/h = 0.5 using GFRP in the tension zone increased the ultimate load by about 11% when compared to steel.

Punching Shear of Flat Slabs with Pultruded GFRP Stay-in-Place Structural Forms

This paper examines the punching shear behavior of a new concrete flat slab design, incorporating a glass fiber-reinforced polymer (GFRP) stay-in-place (SIP) structural form system and orthogonal GFRP top rebar mesh. The SIP form system comprises I-beams supported on the four sides of a column and flat plates with T-up ribs supported by, and adhesively bonded to, the bottom flanges of the I-beams. The web and top flange of the I-beams are embedded in the slab, thereby providing flexural and shear reinforcement, while the SIP ribbed plates provide the bottom reinforcement. Four full-scale interior slab–column specimens, 2000 × 2000 × 200 mm3, were tested under axial compression applied to the column. The slabs have a central 300 × 300-mm square column extending 300 mm on either side of the slab. The study assessed the contributions to punching shear strength of different components of the GFRP system. The new design experienced a 29% higher punching shear strength than the control slab with GFRP rebar only, and was much more ductile. The load dropped gradually over a large range of deflection, increasing the ductility index from 1.6 in the control slab to 3.1 in the slab incorporating the new design. An analytical model is developed for punching shear strength, accounting for concrete contribution and flexural and web contributions of I-beams. Results agreed with experimental strength, within −6% to +13%. A parametric study examined a range of rebar reinforcement ratios, different GFRP I-beam sizes and a comparable steel I-beam.

Mechanical properties and microstructure of glass fiber reinforced polymer (GFRP) rebars embedded in carbonated reactive MgO-based concrete (RMC)

Reactive MgO cement (RMC) is an emerging low-carbon material which can be a sustainable alternative to ordinary Portland cement (OPC) due to its capability to sequester CO2. However, the application of carbonated RMC concrete in conventional steel reinforced concrete infrastructure is restricted by its inherent low alkalinity (∼10.4), which cannot protect steel from rusting. To address this issue, glass fiber reinforced polymer (GFRP) rebars can be employed. In this study, the mechanical properties and microstructures of RMC-GFRP exposed to various temperatures (23, 40 or 60 °C) for 21, 45 and 90 days were investigated. Experimental results showed that the low-alkalinity carbonated RMC concrete was less aggressive than the normal concrete (NC) to GFRP rebars, remarkably enhancing the tensile strength retention of GFRP rebars from 73.6% to 90.4% after 90 days of exposure at 40 °C. Micromorphology observation indicated that the higher tensile strength retention was ascribed to the reduced GFRP degradation (i.e., matrix cracking, fiber erosion and fiber/matrix interfacial debonding) under the low-alkalinity condition. Additionally, the flexural strength of 90-day aged RMC- and NC-GFRP samples at 60 °C were close to that of unconditioned GFRP samples (791 MPa and 788 MPa vs. 791 MPa), which was attributed to the unchanged glass transition temperature and stable elastic modulus of GFRP. The RMC- and NC-GFRP samples also showed very little change in inter-laminar shear strength as compared to the unconditioned GFRP samples, as the middle layer of GFRP rebars was well-protected from external water and chemicals. Based on the empirical degradation model and activation energy derived from test results at different temperatures, the predicted tensile strength retention of RMC-GFRP after an extended period (∼100 years) under Canadian climate is still sufficient. This study will shed light on the understanding of degradation mechanism and practical application of GFRP reinforced RMC in infrastructure construction.