MAT-762: BUILDING SUSTAINABLE CONTINUOUSLY REINFORCED CONCRETE PAVEMENT USING GFRP BARS: CASE STUDY-HIGHWAY 40 WEST-MONTREAL, CANADA

Continuously reinforced concrete pavement designs (CRCP) are premium pavement designs that are often used on heavily-trafficked roadways and urban corridors. Although CRCP typically is an effective, long-lasting pavement design, it can develop performance problems when the aggregate-interlock load transfer at the transverse cracks is degraded. The prevalence of wide cracks in CRCP has frequently been associated with ruptured steel and significant levels of corrosion. Because of that, there has been recent interest in identifying new reinforcing materials that can prevent or minimize corrosion-related issues in CRCP. Glass fibre-reinforced polymer (GFRP) bars are one product being investigated for use in CRCP in place of traditional steel bars. This paper summarizes the construction details, material properties, early-age behaviour, and preliminary monitoring results of GFRP CRCP after 12 months in service. The project is located westbound HW-40 in Montreal, Qc, Canada, and presents a collaboration between the Ministry of Transportation of Quebec (MTQ) and the University of Sherbrooke. Varieties of sensors were installed in this project in order to monitor the early-age behaviour and the effects of repeated traffic loads and environmental conditions on the performance of CRCP slabs

Flexural response of GFRP-reinforced geopolymer concrete beams

This study investigated the flexural response of glass fibre reinforced polymer-reinforced geopolymer concrete (GFRP-RGC) beams using a four-point static bending test. Three full-scale beams were cast and reinforced with nearly same amount of longitudinal GFRP reinforcements but of varying diameters at the bottom (4-12.7 mm, 3-15.9 mm, and 2-19.0 mm), two 12.7 mm GFRP bars at the top, and 9.5 mm GFRP stirrups spaced at 100 mm on-centre. The average compressive strength of the geopolymer concrete was 38.2 MPa. Based on the experimental results, all the tested beams showed nearly similar crack pattern, load-deflection response, bending-moment and deflection capacities, and strain readings, suggesting that the flexural response of a GFRP-RGC beam was not significantly influenced by the bar diameter; instead, by the properties of the geopolymer concrete. The 0.3Mu criterion suggested by Bischoff must be adapted in the serviceability design of a GFRP-RGC beam. The flexural capacities of the tested beams were generally higher than the predicted values from ACI 440.1R-06 and CSA S806-12 standards. Furthermore, the GFRP-RGC beams have higher strength compared with their GFRP-reinforced concrete counterparts. Thus, it can be concluded that the GFRP-RGC beams have structural properties that are suitable for civil infrastructure applications

Pullout behaviour of GFRP bars with anchor head in geopolymer concrete

The geopolymer concrete internally reinforced with fibre-reinforced polymer (FRP) bars is anticipated to offer durable, sustainable, and cost-effective civil infrastructures. In this study, the effect of the anchor head on the pullout behaviour of the sand coated glass-fibre-reinforced polymer (GFRP) bars embedded in the geopolymer concrete was investigated using a direct pullout test. Straight and headed GFRP bars with different nominal diameters Ø (12.7 mm, 15.9 mm, and 19.0 mm) and embedment lengths ld (0Ø+lah, 5Ø+lah, and 10Ø+lah for headed bars, where lah stands for the anchor head length, and 5Ø and 10Ø for straight bars) were considered. The results showed that the provision of anchor head is an efficient method to enhance the anchorage capacity of GFRP bars in geopolymer concrete. The anchor heads improved the anchorage of the sand coated GFRP bars by as much as 49% to 77%. Furthermore, the mechanical bearing resistance provided by the anchor head alone resulted in the development of approximately 45% of the GFRP bars’ nominal tensile strength. A comparison of the experimental results with the published studies showed that a much higher load is required to pullout the GFRP bars in geopolymer concrete than in Ordinary Portland Cement-based concrete

Behaviour of concentrically loaded geopolymer-concrete circular columns reinforced longitudinally and transversely with GFRP bars

The behavior of concentrically loaded geopolymer-concrete circular columns reinforced longitudinally and transversely with glass–fiber-reinforced-polymer (GFRP) bars was investigated. Six full-scale short columns (L/r = 8) were cast: one column without transverse reinforcement; three columns with circular hoops spaced at 50 mm, 100 mm, and 200 mm on centers; and two columns with spirals spaced at 50 mm and 100 mm on centers. In addition, two slender columns (L/r = 16) transversely reinforced with hoops and spirals both spaced at 100 mm on centers were fabricated. Based on the experimental results, the GFRP bars contributed an average of 7.6% to the overall capacity of the tested columns. The hoop- and spiral-confined slender columns failed at a load equal to 66% and 82%, respectively, of the strength of their counterpart short columns. Irrespective of the tie configuration, the columns with higher volumetric ratios showed better compressive behavior than those with lower volumetric ratios. The ductility and confinement efficiency of the spiral-confined columns were higher than that of their counterpart hoop-confined columns. The tested columns yielded relatively superior compression performance compared to OPC-based concrete columns reinforced with GFRP bars and ties. Further studies dealing with the behavior and slenderness limit in GFRP-reinforced geopolymer concrete slender columns are recommended to increase its uptake in the construction industry

Evaluation of the flexural strength and serviceability of geopolymer concrete beams reinforced with glass-fibre-reinforced polymer (GFRP) bars

Geopolymer concrete reinforced with glass-fibre-reinforced polymer (GFRP) bars can provide a construction system with high durability, high sustainability, and adequate strength. Few studies deal with the combined use of these materials, and this has been the key motivation of this undertaking. In this study, the flexural strength and serviceability performance of the geopolymer concrete beams reinforced with GFRP bars were evaluated under a four-point static bending test. The parameters investigated were nominal bar diameter, reinforcement ratio, and anchorage system. Based on the experimental results, the bar diameter had no significant effect on the flexural performance of the beams. Generally, the serviceability performance of a beam is enhanced when the reinforcement ratio increases. The mechanical interlock and friction forces provided by the sand coating was adequate to secure an effective bond between the GFRP bars and the geopolymer concrete. Generally, the ACI 4401.R-06 and CSA S806-12 prediction equations underestimate the beam strength. The bending-moment capacity of the tested beams was higher than that of FRP-reinforced concrete beams from the previous studies

Continuous Concrete Beams Reinforced With CFRP Bars.

yesThis paper reports the testing of three continuously and two simply supported concrete beams reinforced with carbon fibre reinforced polymer (CFRP) bars. The amount of CFRP reinforcement in beams tested was the main parameter investigated. A continuous concrete beam reinforced with steel bars was also tested for comparison purposes. The ACI 440.1R-06 equations are validated against the beam test results. Test results show that increasing the CFRP reinforcement ratio of the bottom layer of simply and continuously supported concrete beams is a key factor in enhancing the load capacity and controlling deflection. Continuous concrete beams reinforced with CFRP bars exhibited a remarkable wide crack over the middle support that significantly influenced their behaviour. The load capacity and deflection of CFRP simply supported concrete beams are reasonably predicted using the ACI 440.1R-06 equations. However, the potential capabilities of these equations for predicting the load capacity and deflection of continuous CFRP reinforced concrete beams have been adversely affected by the de-bonding of top CFRP bars from concrete

A New Design-Oriented Model of Glass Fiber-Reinforced Polymer-Reinforced Hollow Concrete Columns

Hollow concrete columns (HCCs) reinforced with glass fiber-reinforced polymer (GFRP) bars and spirals are considered an effective design solution for bridge piers, electric poles, and ground piles because they use less material and maximize the strength-toweight ratio. HCC behavior is affected by critical design parameters such as inner-to-outer diameter ratio, reinforcement and volumetric ratios, and concrete compressive strength. This paper proposes a new design-oriented model based on the plasticity theory of concrete and considering the critical design parameters to accurately describe the compressive load-strain behavior of GFRP-reinforced HCCs under monotonic and concentric loading. The validity of the proposed model was evaluated against experimental test results for 14 full-scale hollow concrete columns reinforced with GFRP bars and spirals. The results demonstrated that the proposed design-oriented model was accurate and yielded a very good agreement with the axial compressive load behavior of GFRP-reinforced hollow concrete columns

Comparison of the shear behaviour of geopolymer concrete beams with GFRP and steel transverse reinforcements

This study presents a comparison of the shear behaviour of geopolymer concrete beams transversely reinforced with glass fiber-reinforced polymer (GFRP) and steel bars. Two full-scale beams with GFRP and steel stirrups spaced at 150 mm on-center were fabricated and tested up to failure using the four-point static bending test. Another beam without web reinforcements was also cast to determine the shear contribution of the geopolymer concrete. All the beams were provided with the same amount of flexural reinforcements. The beams were supported over a 1200 mm clear span with 450 mm shear span on each side. The shear span-to-depth ratio of the beams was 1.8. Based on the test results, the provision of GFRP stirrups almost doubled the shear capacity of the beam without web reinforcements. Comparable load-deflection response, shear strength, deflection capacity, and strain readings were observed between the beams with GFRP and steel stirrups. The two beams yielded similar crack pattern; however, wider cracks were developed in the former beam owing to the lower elastic modulus of GFRP bar compared with steel bar. Furthermore, both beams failed in shear, classified as a diagonal strut compression failure; however, the failure of the beam with GFRP stirrups was induced by the stirrup’s lap splice failure while steel yielding caused the failure of beam with steel stirrups. This had led to a more brittle final failure of the former beam compared with the latter beam

Hollow concrete columns: review of structural behavior and new designs using GFRP reinforcement

Hollow concrete columns (HCCs) reinforced with steel bars have been employed extensively for bridge piers, ground piles, and utility poles because they use fewer materials and offer higher structural efficiency compared to solid concrete columns with the same concrete area. Many experimental studies have been conducted to investigate the behavior of HCCs under different loading conditions and found that the structural performance of HCCs is critically affected by many design parameters. If not designed properly, HCCs exhibit brittle failure behavior, due to longitudinal bars buckling or the concrete wall failing in shear. In addition, the corrosion of steel bars has become an issue in reinforced-concrete structures. Therefore, this paper critically reviews the different design parameters that affect the performance of HCCs and identifies new opportunities for the safe design and effective use of this construction system. Moreover, the use of GFRP bars as reinforcement in hollow concrete columns is explored with the aim of developing a non-corroding and structurally reliable construction system

Novel testing and characterization of GFRP bars in compression

Glass fibre reinforced polymer (GFRP) bars have now been increasingly used as longitudinal reinforcement in concrete columns. In column design and analysis, the contribution of GFRP bars to compression is often ignored or is estimated as a fraction of its tensile strength due to the limited understanding on their compressive behaviour. Moreover, there exists no standard test method to characterise the properties of GFRP bars in compression. This study implemented a novel test method to determine and characterise the compressive properties of high modulus GFRP bars. During the preparation of test specimens, hollow steel caps filled with cementitious grout were used to confine the top and bottom ends of the GFRP bars. The effects of the bar diameter (9.5, 15.9, and 19.1 mm) and the unbraced length-to-bar diameter ratio, Lu/db (2, 4, 8, and 16) were investigated on the compressive strength of the bars. The results showed that the increase in bar diameter increases the micro-fibre buckling and decreases the compressive-to-tensile strength ratio. Similarly, the failure mode changed from crushing to fibre buckling with the increase of Lu/db ratio. Simplified theoretical equations were proposed to reliably describe the compressive behaviour of GFRP bars with different bar diameters and Lu/db ratios