Behaviour Of Geopolymer Concrete Research Articles

Performance of fly ash/GGBFS based geopolymer concrete with recycled fine and coarse aggregates at hot and ambient curing

The incorporation of recycled aggregates in geopolymer concrete (GPC) exhibits higher environmental sustainability due to its ability to utilize industrial by-products and construction and demolition (C&D) waste. This study investigates the combined effect of fine and coarse recycled aggregates on the behavior of GPC. In this research, fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used as binder, whereas sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) were used as alkaline activators. Recycled fine aggregates (RFA) were used at 30%, 60% and 100% replacement of natural fine aggregates (NFA) and recycled coarse aggregates (RCA) were used at 0%, 50% and 100% replacement of natural coarse aggregates (NCA). To study the effect of curing temperature, two types of curing regimes, i.e. hot and ambient curing, were employed. Performance of developed GPC was evaluated in terms of workability, mechanical properties (compressive strength, splitting tensile strength, and flexural strength) and durability properties such as water absorption, sorptivity, resistance against acid attack, resistance against marine environment and electrical resistivity. It was found that the behavior of GPC is improved when the samples were cured at high temperature for 24 h, as compared to the samples cured under ambient curing conditions. Furthermore, NFA can be replaced up to 100% with NCA, and up to 60% in the presence of 50% RCA and up to 30% in the presence of 100% RCA. It was also found that with an increase in the percentage of recycled aggregates, durability performance gradually declined. The results showed that GPC can be developed with inclusion of both recycled fine and coarse aggregates, which can help to preserve valuable natural resources, reduce CO2 emission, and dispose C&D waste.

Mechanical properties of basalt macro fibre reinforced geopolymer concrete

Growing public environmental awareness leads to an increased focus on utilizing green and sustainable materials in infrastructure construction. Geopolymer concrete (GPC) and basalt macro fibres (BMFs) are promising construction materials due to their eco-friendly merits and excellent mechanical properties. In this study, a new type of BMFs reinforced GPC (BMF-GPC) was developed, and the compressive and flexural properties of BMF-GPC were investigated. The effects of BMF content and length on the mechanical properties of GPC were studied. It was found that with the addition of 2 % BMFs, the compressive and flexural toughness (energy absorption capacities) of GPC were greatly enhanced by up to 126 % and 965 %, respectively. Increasing the content and length of BMFs resulted in favourable outcomes for strain softening of GPC under compression and post-cracking behaviour of GPC under flexural loads, whilst having limited effects on the modulus of elasticity and flexural strength. Additionally, an analytical model was proposed to predict the compressive stress-strain behaviour of BMF-GPC, which could be used for the design of BMF-GPC structures.

Experimental investigation of the effect of longitudinal tensile reinforcement ratio on ductility behaviour in GPC beams

This research first determined the strength of the cylindrical geopolymer concrete materi- als under compressive stresses. Secondly, conventional and geopolymer-reinforced concrete beams were manufactured in different reinforcement ratios, and their mechanical properties were compared under bending. The main aim of this study is to experimentally compare the effect of reinforcement ratio on the ductility behavior of an alkali-activated geopolymer con- crete (GPC) beam with that of an ordinary Portland cement (OPC) beam. First, balanced reinforcement calculations were made considering the mechanical properties obtained from the material tests. The load-displacement, moment-curvature, and crack development results obtained from beam tests are interpreted with this information. OPC and GPC beams exhibit- ed similar strength and crack development behavior. However, the behavior of GPC and OPC concretes differs regarding the ductility index. Therefore, to achieve similar ductility in the conduct of GPC and OPC beams, the balanced reinforcement ratio and section dimensions of GPC beams should be chosen to be larger than OPC.

Comparative fracture properties of ambient-cured geopolymer concrete containing four different fibers in mono and hybrid combinations using digital image correlation

This paper presents an investigation on the effects of four different fibers (polypropylene (PP), polyvinyl alcohol (PVA), recycled polypropylene (RPP), and steel (S) fibers) on the fracture behaviour of ambient-cured fly ash geopolymer concrete (GPC). The four fibers were added into GPC by both mono at 1.0% volume and hybrid combinations with steel fiber at 0.5% of each other type of fiber. The full-field strain distribution and the crack mouth opening displacement (CMOD) were monitored by digital image correlation (DIC) technology. The results reveal that adding fibers was effective in enhancing the fracture performance and hindering the cracking behaviour of GPC. Furthermore, 1.0% volume steel fiber exhibited to be most advantageous in enhancing the flexural strength by 100%, flexural toughness by 4000%, fracture energy by 3897%, and critical stress intensity factor by 98.8%. GPC with 1.0% volume PP fiber exhibited a characteristic length of 7909 mm, improving the characteristic length of GPC by about 2925%. Additionally, the CMOD was found to have a strong linear relationship with deflection which is unaffected by other factors. The presence of fibers significantly enhanced the ultimate strain. The steel fibers exhibited better performance in hindering the crack propagation. The fracture process zone (FPZ) characteristics differed between specimens with non-metallic and steel fibers, with the latter exhibiting more tortuous shapes and multiple cracks. Notably, a hybridization of steel and non-metallic fibers proves better than mono non-metallic fibers in improving strength, toughness, and ductility. This research provides valuable insights for concrete design and the selection of appropriate fibers based on specific requirements.

Pore structure profile of ambient temperature-cured geopolymer concrete and its effect on engineering properties

Ambient temperature-cured geopolymer concrete (GPC) with solid alkali activators are attracting attention as an eco-friendly alternative to OPC-based concrete (OPCC) for industrial applications. This research investigates the pore structure and microstructural characteristics of GPC via porosimetry and micrography and strives to connect the micro-scale characteristics to macro-scale engineering properties. The dominance of slag and low water content resulted in a denser and more homogenous microstructure in the binder with fewer microcracks and voids. Furthermore, a refined pore structure was observed when the fly ash/slag ratio was 60/40. The porosimetry analysis demonstrated that OPCC possessed a uniform pore structure with a similar porosity profile throughout the concrete cross-section. GPC showed a descending pore gradation profile from top to bottom. The difference in the pore structure profiles can explain the previously witnessed shrinkage behaviour of GPC and OPCC in restrained conditions.

Axial compressive behaviour of GPC filled FRP Tubes: Experimental and analytical investigations

The production of Ordinary Portland Cement (OPC) releases carbon dioxide (CO2), which is one of the main contributors in the rising level of Greenhouse Gases (GHG) into the atmosphere and adversely effecting the environment and subsequently causing the climate change. In this study, the fly ash (FA) an alternative of OPC is used to produce environmental friendly cementless geopolymer concrete (GPC). This study investigates the axial compressive behavior of GPC filled fiber reinforced polymer (FRP) tubes. Two types of FRP tubes, i.e., carbon FRP (CFRP) tubes and glass FRP (GFRP) tubes were prepared by the wet lay-up procedure using CFRP and GFRP sheets, respectively. A total of forty-five GPC specimens of 150 mm diameter and 300 mm height were prepared with five different molarity of NaOH (8–16 M) with Na2SiO3 to NaOH ratio of 1.5. The unconfined GPC (Control), GPC filled CFRP tube (GCT) and GPC filled GFRP tube (GGT) specimens exhibited a significant increase in the peak axial stress (fc) with the increase in the molarity of NaOH. The scanning electron microscopic investigation also exhibited a reduced number of unreacted fly ash particles in the GPC with increasing the molarity of NaOH. The fc and corresponding axial strains (∊c) of GCT and GGT specimens were significantly higher than those of unconfined GPC specimens. The GCT specimens exhibited higher fc and corresponding ∊c than the GGT specimens. The analytical axial stress–strain (fc-∊c) curves of GCT and GGT specimens developed using available fc-∊c models of FRP confined ordinary Portland cement (OPC) concrete matched well with the experimental fc-∊c curves of GCT and GGT specimens.

Behaviour of geopolymer concrete at elevated temperature- a comprehensive review

In comparison to conventional materials made of concrete, geopolymer materials are sustainable, durable and strong. Geopolymer used should not only be sustainable but also fire-resistant for the necessary amount of time. The properties of geopolymer materials after high-temperature exposure, such as weight loss, thermal expansion, thermal conductivity, mechanical properties, and microstructure are reviewed and discussed in detail in the current study. In addition, the behaviour of Geopolymer concrete (GPC) at high temperatures with different recycled fibre additions as well as additions of crumb rubber is also examined in this article. The use of recycled fibres made from industrial wastes offers additional advantages, including resource conservation, waste reduction, lower costs of processing than normal fibres, and the removal of waste disposal in landfills. The latter offers a sustainable method for recycling tyres and helps slow down the depletion of natural aggregates. From the literature, it is revealed that at 800–1000 °C, compared to the OPC concrete specimens, the GPC samples had less cracking damage and also substantial spalling was seen in the OPC samples, but not in the GPC samples. GPC with recycled fibres has higher crack-resistant characteristics at elevated temperatures. Meanwhile, in a study at 800 °C, rubberized geopolymer showed more cracks compared to control GPC. This work also provides comprehensive reviews on the type of recycled fibres and rubber aggregates, spalling mechanisms, physical inspection and properties of rubberized geopolymer and recycled fibre-reinforced GPC. It also demonstrated the influence of elevated temperature on the characteristics of recycled fibre-reinforced GPC and rubberized geopolymer after high-temperature exposure.

Influence of solution binder ratio on behaviour of Ground Granulated Blast-Furnace Slag based Geopolymer Concrete

In recent years the word sustainability has become a priority of many researchers. In this regard, many evolutions were put forth in the concrete industry one of them is Geopolymer concrete. Ground granulated blast furnace slag (GGBS) is used as source material which is rich in alumina and silica contents, which forms alumina silicate gel when mixed with an alkali solution of sodium hydroxide and sodium silicate which then binds with aggregate. Till now many researchers had done research on Geopolymer concrete using Fly ash as major binding material. Literature is also available on Geopolymer concrete with GGBS as major binding material but the behaviour of Geopolymer concrete was not studied widely by varying solution binder ratio. In this research, the behaviour of GGBS based Geopolymer concrete was studied, by replacing fly ash with 0%, 10%, 20% and 30% and varying solution/binder (s/b) ratio 0.3, 0.4, 0.5 and 0.6. The mix proportions were prepared by taking a ratio of 1:1:3 by weight and all the specimens were cured at ambient temperature. Mechanical properties such as compressive strength, tensile strength and flexure strength were determined. A sulphate attack test was also conducted. As quantity of FA increased, strength decreased.

Bond behavior of geopolymer concrete with steel and GFRP bars

In the last years geopolymer concrete (GPC) has shown great potential for use in structural elements. In this context, it has become fundamental to investigate on the bond behavior of this new concrete matrix with reinforcing bars. Data found in literature showed that GPC performs better than ordinary Portland cement (OPC) concrete in terms of bonding with deformed steel bars. In addition, few authors have focused in the study of the bond stress-slip behavior between GPC and glass fiber-reinforced polymer (GFRP) rebars. In this paper the bond-slip behavior of GPC with both steel and GFRP reinforcing bars will be investigated by means of pull-out test with centered bar setup also considering the effect of the bond length. The main results showed that little difference in bond-slip behavior occur between the two different steel bar diameters used. On the other hand, sand-coated GFRP bars showed lower bond capacity in respect to deformed steel bars. Finally, an increase in ultimate bond load has been observed when the bond length was increased.

Effect of Metakaolin on Mechanical Properties and Flexural Behavior of Geopolymer-Reinforced Concrete Beams

Among various eco-friendly building products, geopolymers are emerging as a potential replacement material for ordinary portland cement due to its energy efficiency and environmental protection. Though various eco-friendly cementitious materials in combination with geopolymer concrete (GPC) have been studied by various researchers, their effect on the behavior of GPC made with ground granulated blast furnace slag (GGBS) and metakaolin (MK) is, however, not well established. This paper investigates the mechanical properties of GPC and flexural behavior of geopolymer-reinforced concrete beams, comprising various percentages of fly ash (FA), GGBS, and MK. The FA was partially replaced with various proportions of GGBS and MK. All the concrete specimens are cast for 10 molarity (10M) and are tested as per Indian standard code. The compressive, split tensile, and flexural strength of the F50G25M25 (50% fly ash + 25% GGBS + 25% MK) mix are increased by 147.75%, 57.21%, and 36.08% respectively, over the control specimen (F90G5M5) (90% fly ash + 5% GGBS + 5% MK). The ultimate load-carrying capacity of a geopolymer reinforced concrete beam was enhanced by up to 30.43% for F50G25M25 mix. The experimental ultimate loads are compared with theoretical predicted loads, and good agreement with the theoretical model is found. Replacement of FA by GGBS and MK at 25% each significantly increased the mechanical properties and flexural behavior of GPC. Other cementitious materials beyond those used in this paper could be used to investigate the mechanical properties of GPC.

Strength Behaviour of Geopolymer Concrete by using Different Mineral Admixtures

The world is developing rapidly and therefore the construction of buildings takes vital role. If we bear thoroughly the usage of concrete gets raised up so it ends up in the shortage of the natural resources. so as to save lots of our natural resources, by replacing a number of the proportions within the concrete with the subsequent measures. By using ash and GGBS as admixture in geopolymer concrete in equal percentages (50-50%). The results obtained from compressive strength, split durability test for the age of 7-and 28-days strength-polymer concrete is one among the building materials that became more popular in recent years thanks to the very fact that it's significantly more environment friendly than standard concrete-polymer concrete could be a variety of concrete that's made by reacting aluminates and silicate bearing materials with a caustic activator. Commonly, waste materials like ash or slag from iron and metal production are used, which helps result in a cleaner environment. Geo-polymer concrete completely replaces cement by ash, ground granulated furnace slag and therefore the polymer materials.

Experimental Investigation on Production, Mechanical Properties, and Behaviour of GPC at Elevated Temperature

In the current study, concrete of M60 grade is used for both Normal Concrete (NC) and Geopolymer Concrete (GPC). Optimum mix design values for GPC are obtained by trial and error method as per Rangan’s method. Concrete specimens, such as cube, cylinder, and prism, are casted as per optimum mix design values and are tested for mechanical properties namely compressive strength, flexural strength, and split tensile strength at the age of 7, 14, and 28 days. Comparative analysis of NC and GPC is done for aforementioned strength test results. Later behaviour of GPC is checked at elevated temperatures of 200°C, 300°C, and 400°C. From the results, it is observed that GPC performed well in terms of all mechanical properties compared to NC. An overall observation confirms that GPC performed better at higher temperatures. Thus, it is effectively proved that GPC is best alternative to NC.

Reviewing mechanical performance of geopolymer concrete containing coal bottom ash

Concrete is one of the most demanding construction materials and also the third-largest emitter of greenhouse gases on the planet. Likewise, cement is a commonly used binder in concrete and its production accounts for nearly 7 percent of global greenhouse gasses resulting it into one of the most non-sustainable options. Geopolymer concrete (GPC) is a type of construction material made with the utilization of the waste products of industries (like fly ash, copper slag, coal bottom ash, etc.). It comprises the process of geopolymerisation with the help of alkali activators particularly made of sodium hydroxide and sodium silicate. Further, Coal Bottom ash (CBA), generated from thermal power plants is generally landfilled and has already created serious threats to the environment. The current review summarizes the present and past research trends of mechanical behavior of GPC made with different amounts of CBA either used as replacement of binder or as fine aggregates. Generally, the mechanical properties of GPC depend on various parameters like alkali solution content, liquid/binder ratio, molarity of NaOH, NS/NH ratio, grinding of CBA and type of curing. The literature indicates that, an increase in various parameters such as NS/NH ratio (1.5–4.9), molarity of NaOH (10 M−16 M) and the grinding period (12 h–36 h) improves the overall mechanical properties. Likewise, an increase in liquid/binder ratio (0.5–1) and alkali content reduces the strength properties of CBA based GPC at different curing regimes. The findings also suggest the adequate potential of CBA to be used as primary/secondary material in Geopolymer concrete. Last, the study briefly highlights the challenges and future scope of application of CBA in developing GPC.

Behavior of Quarry Rock Dust, Fly Ash and Slag Based Geopolymer Concrete Columns Reinforced with Steel Fibers under Eccentric Loading

Geopolymer concrete, also known as an earth-friendly concrete, has been under continuous study due to its environmental benefits and a sustainable alternative to conventional concrete construction. The supplies of many source materials, such as fly ash (FA) or slag (SG), to produce geopolymer concrete (GPC) may be limited; however, quarry rock dust (QRD) wastes (limestone, dolomite, or silica powders) formed by crushing rocks appear virtually endless. Although significant experimental research has been carried out on GPC, with a major focus on the mix design development, rheological, durability, and mechanical properties of the GPC mixes; still the information available on the structural behavior of GPC is rather limited. This has implications in extending GPC application from a laboratory-based technology to an at-site product. This study investigates the structural behavior of quarry-rock-dust-incorporated fiber-reinforced GPC columns under concentric and eccentric loading. In this study, a total of 20 columns with 200 mm square cross-section and 1000 mm height were tested. The FA and SG were used as source materials to produce GPC mixtures. The QRD was incorporated as a partial replacement (20%) of SG. The conventional concrete (CC) columns were prepared as the reference specimens. The effect of incorporating quarry rock dust as a replacement of SG, steel fibers, and loading conditions (concentric and eccentric loading) on the structural behavior of GPC columns were studied. The test results revealed that quarry rock dust is an adequate material that can be used as a source material in GPC to manufacture structural concrete members with satisfactory performance. The general performance of the GPC columns incorporating QRD (20%) is observed to be similar to that of GPC columns (without QRD) and CC columns. The addition of steel fibers considerably improves the loading capacity, ductility, and axial load–displacement behavior of the tested columns. The load capacities of fiber-reinforced GPC columns were about 5–7% greater in comparison to the CC columns. The spalling of concrete cover at failure was detected in all plain GPC columns, whereas the failure mode of all fiber-reinforced GPC columns is characterized with surface cracking leading to disintegration of concrete cover.

Durability performance of fly ash-based geopolymer concrete buried in saline environment for 10 years

Durability of geopolymer concrete is an important property for its application in construction sector; however, it is less explored. In this study, the long-term durability of fly ash-based geopolymer concrete (GPC), exposed in a severe salt lake environment with the buried and fully saturated condition for 10 years, is investigated. The outcome of chloride and sulphate attack on the durability behaviour of GPC was compared to ordinary Portland cement (OPC) concrete at the same exposure conditions. The results of this study reveal that the GPC has an adverse effect of chloride transportation with higher chloride diffusion coefficient and the lower binding capacity, compared to OPC concrete. The sulphate penetration of GPC was also greater than OPC concrete, however, its detrimental effect has been found more pronounced in OPC concrete due to the gypsum formation resulting in the softening of its matrix. The pH measurement indicated that the GPC has the neutral to mild alkalinity with the pH range of 7.0–8.0, whereas OPC concrete showed between 12.0 and 12.5. The mineralogical and morphological changes within the microstructure as a result of long term exposure in the buried saline environment were also studied by FT-IR and SEM/EDX analysis.

Corrosion Evaluation of Geopolymer Concrete Made with Fly Ash and Bottom Ash

Environmental pollution caused by CO2 releasing from the production of cement is a great challenge for the construction industry and has triggered exploration into more sustainable alternatives. Geopolymer Concrete (GPC) is a potential sustainable solution that does not involve the use of cement as a binder. GPC is produced by mixing the alumino-silicate source materials such as fly-ash with alkali activators such as potassium hydroxide (KOH) and potassium silicate (K2SiO3). Unlike Ordinary Portland Concrete (OPC), the characteristics of GPC depend on the precursor materials and therefore vary for different mixes. Consequently, corrosion behavior needs to be evaluated separately for individual mixes. This has narrowed the scope of existing published work on corrosion behavior of GPC. In this study, GPC and OPC specimens were prepared and exposed to accelerated corrosion exposure. Half-cell potential and linear polarization resistance were used to evaluate the corrosion rate in GPC and OPC. Under accelerated conditions, the corrosion rate of the GPC specimens was between 10 µm/year and 20 µm/year exhibiting a moderate to high rate of corrosion. Meanwhile, the corrosion rate of the OPC specimens was between 40 µm/year and 60 µm/year indicating a very high corrosion activity. It can be concluded that GPC has a higher resistance to chloride-induced corrosion; with a low corrosion rate and lower mass loss percentage, compared to OPC.

Mathematical model for predicting stress-strain behavior of low calcium fly-ash based geopolymer concrete

The focus of the study was to identify the stress strain behavior of geo polymer concrete and salient parameters that influence the mixture proportions and the properties of low calcium fly ash- based geo polymers concrete. To develop geopolymer concrete the chemical proportions are alkaline liquid solution/fly-ash ratio=0.5, Sodium silicate/sodium hydroxide ratio=2.5,16M NaOH and SiO2/Na2O ratio=2.0. The geopolymer concrete mixes have shown improved stress values for the same strain levels compared to that of controlled concrete mix. Normalized stress strain curves are used to compare the behaviours of geopolymer concrete. It can be observed that geopolymer concrete has improved strains for the same stress when compared to conventional concrete. Geopolymer concrete mixes have shown improved stress values for the same strain levels compared to that of controlled concrete mixes.

Effect of Sugarcane Bagasse Fibre on the Behavior of Geopolymer Concrete under Sulphate Attack

The use of various fibres such as steel, glass, sugarcane bagasse, and others has a considerable impact on the fresh and hardened properties of concrete. Sugarcane bagasse fibre is a byproduct from the sugarcane industry that can be reused as a concrete fibre. This paper objective is to work on the behaviour of sugarcane bagasse fibre on low calcium fly ash and slag based geopolymer concrete of G40 which is equivalent to M40 grade, when it is exposed to 5% sulphate attack with the help of experiments. The specimens were casted, GPC and GPCF Cured in an oven at 60 ° C for 24 hours, then let to cure in the atmosphere until the test is complete. After 28 days, the specimens were immersed in sulphates such as Na2SO4 and MgSO4 for 15, 45, and 75 days, and then tested according to codal standards on 15, 45, and 75 days. The comparisons were made in a controlled concrete environment (CC), controlled concrete with sugarcane bagasse fibre (CCF), geopolymer concrete (GPC) and geopolymer concrete with sugarcane bagasse fibre (GPCF). From the results it is observed that CCF and GPCF showed more resistant than CC and GPC when it is subjected to sulphate attack.

Characteristics of metakaolin-based geopolymer concrete for different mix design parameters

Geopolymer is emerging as a potential alternative material to the ordinary Portland cement (OPC) owing to its energy efficiency and environmental protection. However, the effect of the mix design parameters on the behavior of geopolymer concrete (GPC) produced using local metakaolin (MK) is not well established. This paper presents findings from a comprehensive experimental program to study the effect of various mix design parameters on the properties of fresh and hardened MK-based GPC. Seventeen mixes were cast in four groups to investigate the effect of four parameters, including sodium silicate to sodium hydroxide ratio, alkaline solids to MK ratio, aggregate content, and water to solids ratio on the properties of GPC. The investigated properties included workability, density (wet and dry), development of compressive strength with age, splitting tensile strength, ultrasonic pulse velocity, water absorption, and horizontal abrasion resistance. Besides, two reference OPC concrete mixes, equivalent to two MK-based geopolymer mixes, were tested for the sake of comparison. The test results were helpful in developing a better understanding of the behavior of MK-based GPC. Some useful models are proposed for predicting workability, splitting tensile strength, water absorption, and weight loss in abrasion for MK-based GPC. The test results were supplemented and confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis performed on some selected GPC mixes.

Flexural Capacity and Behaviour of Geopolymer Concrete Beams Reinforced with Glass Fibre-Reinforced Polymer Bars

Geopolymer concrete (GPC) with Glass fibre-reinforced polymer (GFRP) bars can provide a better construction system with high sustainability, high durability, and adequate strength. Few studies deal with the combination of these materials. The present investigation obtains the flexural capacity and behaviour of GPC and ordinary Portland concrete beams reinforced with GFRP bars (GFRP-RGPC and GFRP-ROPC, respectively). Twelve beams consisting of nine GFRP-RGPC and three GFRP-ROPC beams were cast and tested by using the four-point bending test over an active span of 2000 mm. Rebar ratio, compressive strength, and concrete types were taken as the variables. Initial cracking load, ultimate load capacity, load–deflection behaviour, Load–strain curves, crack width, the number of cracks and failure modes, were studied. Experimental results of beams were compared with the proposed equations provided by ACI 440.1R-15, CSA S806-12, and parabolic stress block method. The Results showed the decrease of deflection and increase of first cracking load by increasing the compressive strength. A slight increase in the deflection of GFRP-RGPC beams and approximately the same value of ultimate load were observed. GFRP-RGPC beams also recorded a higher value of crack width compared with GFRP-ROPC beams. The parabolic stress block method predicted the flexural capacity of the beams close to the experimental results rather than ACI 440.1R-15 and CSA S806-12.