Fibre Reinforced Geopolymer Concrete Research Articles

High-strength steel fibre-reinforced geopolymer concrete utilising recycled granite waste and rice husk ash

A limited number of research studies have managed to attain high-strength geopolymer concrete, especially by utilising waste materials. In this study, granite waste (GW) from the mining industry, which contaminates the surrounding environment and causes air pollution, and rice husk ash (RHA) from agricultural waste were used to produce high-strength steel fibre-reinforced geopolymer concrete (HSFRGC). To reduce natural sand consumption, GW was utilised as a fine aggregate. RHA was added at 0%, 1%, 3%, and 5% by weight of coal fly ash to enhance the properties of HSFRGC. In addition, hooked-end steel fibres were employed as reinforcement at 0%, 0.5%, and 1% by volume of the concrete. The objective of this study is to investigate the effect of incorporating GW and RHA into HSFRGC, examining properties such as workability, strength, durability, and microstructure. Additionally, an assessment was conducted on the environmental impact and cost-effectiveness of the HSFRGC system with additives to determine its feasibility for practical scenarios. The results showed that the addition of 1% RHA as an additive in the geopolymer system, which led to microstructural homogeneity in the geopolymer matrix, could effectively enhance the mechanical properties and durability. Moreover, the addition of hooked-end steel fibres along with 1% RHA further improved the mechanical performance compared to samples without steel fibres, increasing both compressive strength by 25% and flexural response by 70%. Meanwhile, incorporating 1% RHA in mixtures could assist in mitigating chloride migration by approximately 10% due to the filler effect occurring in the geopolymer matrix. Regarding to environmental impact and cost-effectiveness, the incorporation of 1% RHA and 0.5% steel fibre demonstrated a suitable balance, exhibiting eco-strength efficiency with an increase of 15% compared to plain geopolymer concrete, making it a reasonable choice for both environmental concerns and cost efficiency.

Experimental Evaluation of Mechanical Properties, Micro Structure and Post-Fire Strength of Fiber Reinforced Geopolymer Concrete

Geopolymer mixtures offer an enhanced alternative to implement an eco-friendly solution in construction industry. These mixtures exhibit similar or better mechanical and structural properties in comprising of cement and can use recycling and by-product materials. Against this background, an eco-friendly advantageous were achieved from the engineers and researchers by using waste materials to replace cement and attention to reduce CO2 emission during its procedure. This study attempted to evaluate compressive and tensile strength, micro structure and post-fire characteristic of the geopolymer mixtures. For this aim, the geopolymer mixtures were exposed to elevated temperature between 200, 500 and 800 0C. Then, the post-fire and mechanical behaviour were investigated. The proposed research supported the slight decrease in the GPC's compressive stress by fibres, and the 1.25% PP fibres displayed the least performance, indicating nearly 13% decrease than the unreinforced mixtures. As exhibited by the post-fire behaviour of mixtures, the GPC's compressive strength increased first for all mixes but in the range of 400 - 800°C it decreased at a higher rate because of the geopolymer matrix-related dehydration. Besides, fiber melting under high temperatures and the thermal reaction procedure related to free water evaporation reduce the mechanical properties under temperatures ranging from 400°C to 800°C. DOI: https://doi.org/10.52783/pst.349

A Novel Repair Technique of Pre-damaged T-Beams Failing in Shear Using Eco-Friendly Steel Fibre-Reinforced Geopolymer Concrete

AbstractRepair of reinforced concrete structures is required to preserve the adequate performance of these structures throughout their service life. One of the credible techniques is using fibrous concrete as a repair material. In this paper, the performance of steel fibre-reinforced geopolymer concrete (SFRGPC) in the repair of pre-damaged reinforced concrete T-beams (pre-loaded up to 50% of their shear capacity) failing in shear was investigated. Five T-beam series and a four-point loading test were adopted: one reference beam, three beams were repaired with different fibrous ratios of 1, 2, and 3%, and one was repaired with 2% steel fibre and additional U-steel stirrups. The key test results include crack propagation, crack width, initial stiffness, load deflection, peak loads, and strain associated with web stirrups. A clear enhancement was noticed in the performance of the repaired T-beams; their shear capacity was boosted by as much as 45% compared to the control beam. It was also deduced that the beam went from a brittle to a ductile failure mode at 3% SFRGPC and at 2% SFRGPC with U-stirrups. Finally, an analytical model prediction was proposed to predict the shear capacity of repaired T-beams with the SFRGPC. The model showed a satisfactory correlation with experimental results, with an average ratio of 0.995 and a standard deviation of 0.035.

Effect of different surface preparation techniques on the bond behavior of normal and fiber-reinforced geopolymer concrete

Fiber-reinforced geopolymer concrete offers a sustainable alternative to conventional concrete; however, its application to repair and strengthen existing concrete structures is inadequately understood. The effectiveness of repairing and strengthening system depends upon the bond characteristics of existing and overlay concrete. Therefore, the present study aims to assess the bond performance of normal (old) concrete and fiber-reinforced geopolymer (new) concrete (FRGC) using different bond tests such as split tensile, bi-surface shear, and slant shear tests. The performance of four interface preparation techniques has been compared: wire brushing, epoxy, carbon fiber reinforced polymer (CFRP), and glass fiber-reinforced polymer (GFRP). Moreover, the effect of various sizes of groove width on the bond characteristics of old and new concrete interfaces is also investigated. CFRP and GFRP, as surface preparation techniques over plain old concrete surfaces, showed the highest split tensile, bi-surface shear, and slant shear strength. Additionally, the interface prepared with grooves of 40 mm width and 10 mm depth with epoxy represented a 113.5% enhancement in slant shear strength compared to the ungrooved one because of the additional mechanical interlocking provided by the defined shape of the grooves. The composite prepared with FRGC as new concrete performed equivalently and even better in some cases than new normal concrete due to the increased interfacial adhesion and dense transition zone created by PVA fiber. Thus, FRGC, being sustainable, has the tendency to replace conventional concrete as an effective and efficient repairing and strengthening concrete. Finally, the obtained experimental results have been compared with the predicted interfacial shear capacity using different design code models, and amongst them, Eurocode 2 predictions are closest to the experimental results.

Experimental investigation and numeric modelling of the impact performance of basalt fiber reinforced geopolymer concrete

Geopolymer concrete (GC) has been found to have better results than Portland cement concrete (PCC), including lower carbon dioxide emissions, higher compressive strength, and greater durability. The study aims to determine the effects of basalt fiber on GC due to the impact caused by the sudden loading effect. Samples were prepared with different mixing ratios for the experimental process, with PCC used as the control sample. Basalt fibers were added to the samples in three different ratios based on optimal mixing ratios determined through physical and mechanical tests, such as UPV (Ultrasonic Pulse Velocity), compressive strength, and flexural strength. Subsequently, fibrous samples were analyzed using SEM (scanning electron microscopy) and EDS (energy dispersive spectroscopy). A drop-weight experiment was conducted on GC plates measuring 50×50×5 cm, which contained two different fiber ratios that yielded the best mechanical and physical properties. The results were analyzed using numerical modeling methods. No changes in content were made. The sample with the highest impact resistance was found to be the 2% basalt fiber-reinforced GC, with a displacement value 21.21% lower than PCC. The language used is clear, concise, and objective, with a formal register and precise word choice. The text follows a logical structure with causal connections between statements and adheres to conventional academic formatting and citation styles. The ANSYS modeling results indicated an 89.63% similarity with the experimental data regarding the displacement values. Additionally, the study demonstrated that the inclusion of basalt fiber additives enhances the impact resistance of geopolymer concrete. Furthermore, numerical modeling can predict the impact behavior of concrete to a significant extent, eliminating the need for experimental processes.

Lateral impact performances of geopolymer concrete columns reinforced with steel-BFRP composite bars

There is a growing public interest in exploring materials that can enhance the sustainability and durability of conventional steel reinforced concrete (RC) structures, such as geopolymer concrete (GPC) and steel-fibre reinforced polymer composite bars (SFCBs). GPC is produced with industrial waste such as fly ash and slag to replace ordinary Portland cement concrete (OPC), and SFCB is a new reinforcement bar with a layer of fibre reinforced polymer (FRP) enclosing a steel inner core to protect it from corrosion. No studies have ever been reported on the impact-resistant performances of GPC or fibre-reinforced GPC (FRGPC) columns reinforced with SFCBs subjected to vehicle or ship impacts. In this study, GPC/FRGPC columns reinforced with steel-basalt FRP composite bars (SBCBs) were prepared and tested by a pendulum impact testing system. Their impact-resistant performances were compared. It was found that the columns experienced similar damage modes regardless of reinforcement type and fibre content. The addition of hybrid carbon fibres (CFs) and basalt macro fibres (BMFs) could effectively reduce cracking damage and mid height deflections of columns. As compared to steel bar reinforcements, SBCB reinforcements led to similar impact force and maximum mid height deflections, but could reduce the residual mid height deflections of the columns by 7–42% under the impact velocity of 2.64–3.49 m/s, indicating SBCBs have great potential to replace steel bars in constructing more sustainable and durable concrete structures.

Optimizing Fiber Reinforced Geopolymer Concrete: Investigating Alkaline-Activator Liquid to Fly Ash and Sodium Silicate to Sodium Hydroxide Ratio

Optimizing Fiber Reinforced Geopolymer Concrete: Investigating Alkaline-Activator Liquid to Fly Ash and Sodium Silicate to Sodium Hydroxide Ratio

Precast segmental beams made of fibre-reinforced geopolymer concrete and FRP tendons against impact loads

In the open literature, there is no investigation into the impact behaviour of prefabricated segmental concrete beams (PSCBs) cast with low CO2-emission fibre-reinforced geopolymer concrete (GPC), reinforced with non-corrodible basalt fibre-reinforced polymer (BFRP) reinforcement, and post-tensioned with carbon FRP (CFRP) tendons. This research, hence, aims to close this existing gap of knowledge. The primary goals are to investigate the effect of dispersed fibres on the impact response of PSCBs and to compare the performance of CFRP versus steel tendons. The experimental results reveal that the PSCBs fail due to excessive joint openings that lead to concrete spalling and flying concrete debris. The inclusion of dispersed fibres in the concrete postpones crack development, reduces reinforcement strain, and effectively mitigates concrete spalling and stiffness degradation of the beams. While fibres show limited influence on the deflection response of PSCBs, as the deformation of segmental beams is predominantly governed by joint openings with no fibres bridging across the joints, they play a crucial role in preventing severe damage during impact events. The impact response of beams post-tensioned with CFRP tendons is analogous to those with steel tendons. Notably, both the CFRP tendon and BFRP reinforcement remain intact even when the beam fails under impact loads. This implies that CFRP tendons and BFRP reinforcement can be successfully employed in constructing durable and sustainable segmental GPC beams capable of withstanding impact loading. A high-fidelity numerical model of PSCBs made of GPC and FRP tendons and reinforcement subjected to impact loads is also developed, for the first time, to supplement the discussions of experimental findings.

Experimental study on durability properties of kenaf fibre-reinforced geopolymer concrete

The use of fibres in concrete has attracted the interest of many researchers to improve the tensile properties of geopolymer concrete. While adding natural fibres has gained popularity as an eco-friendly alternative to synthetic fibres. This combination of natural fibre-reinforced geopolymer concrete is an interesting composite that has not been reported by many, particularly when kenaf fibre is applied. Hence, this article aims to understand the performance of kenaf fibre-reinforced geopolymer concrete (KFRGC) in terms of water absorption, porosity, sorptivity, water penetration, and resistance against chloride ions penetration and chemical attacks. The results showed that the addition of KF increased the porosity of the geopolymer, thus increasing the water absorption-related properties. It’s observed that the porosity tends to increase with increasing length and volume content of fibres. Compared to control specimens, the highest increment (12.5%) in the porosity was recorded with specimens prepared with a 1.5% volume of fibre and a length of 40 mm. Likewise, the water permeability reading increased with increasing volume and fibre length in the geopolymer matrix. In specimens containing 1.5% fibre, increasing the length of fibre from 20 to 30 mm caused an increment in water permeability from 7.42 cm to 8.9 cm, respectively. However, the chloride, sulphate and acid resistance could be improved due to the ability of the fibres to bridge across the cracks. Furthermore, increasing the length of the fibre to 40 mm, reduced the acid resistance of the proposed concrete and increased the loss of strength to 16.3% and 19.2% at the age of 180 and 365 days, respectively. The outcomes of this research show that using kenaf fibres as a fibrous material in the production of environmentally friendly and durable concrete has a promising future.

Dynamic tensile properties of geopolymer concrete and fibre reinforced geopolymer concrete

Geopolymer concrete (GPC) has attracted much attention over the past decades because it utilizes industry wastes and has outstanding mechanical properties. To improve its ductility and energy absorption capabilities, various types of fibres have been incorporated into GPC. This paper carries out an experimental study to quantify the dynamic tensile properties of GPC and fibre reinforced GPC (FR-GRC) with hooked-end steel fibre and polypropylene (PP) fibre. Both quasi-static and dynamic split-tensile tests are performed on plain GPC and FR-GPC covering strain rates of 10-5s−1 to 16 s−1. The addition of 0.5% volume content of steel and PP fibres is found to effectively improve the ductility of GPC at both static and dynamic states. Under quasi-static loading, the crack opening displacements reach about 0.15 mm for GPC, 9 mm for SGPC and 8 mm for PPGPC upon failure, and when subjected to impact loading, the crack-opening rate of GPC is higher than that of FR-GPC. Fibre stretching process after concrete crack till pull-out/fracture is observed which considerably contributes to the reduction of crack expansion and the enhancement of energy dissipation capacity of GPC, with enhancements reaching up to 33% for PPGPC and 94% for SGPC. The split-tensile properties of both plain GPC and FR-GPC are found to be sensitive to strain rate, while geopolymer with PP fibre shows a similar behaviour as plain geopolymer, and GPC with steel fibres appears to be less sensitive to strain rate effect. Empirical relations are proposed to correlate the dynamic increase factor (DIF) of tensile strength for GPC and FR-GPC with strain rate. Comparison between plain GPC and FR-GPC shows that fibres can absorb additional energy to improve the impact resistance and deformation capacities.

Effect of fibre characteristics on physical, mechanical and microstructural properties of geopolymer concrete: A comparative experimental investigation

AbstractThe main aim of this work is to comparatively reveal the effect of fibre type, length and content on compressive strength and microstructure of structural geopolymer concrete (GPC) produced under constant mixture and curing parameters in order to address the significant gap in present literature. Firstly, GPCs with different NaOH concentrations (i.e., 6, 9, 12 and 15 M) and activator solution/binder (a/b) ratios (i.e., 0.45 and 0.55) were produced in ambient curing condition, and optimum production parameters were determined based on the preliminary evaluations. Then, glass and polypropylene fibres in 6‐mm length (GS6 and PP6) and polyamide and polypropylene fibres in 12‐mm length (PY12 and PP12) were included in GPCs at ratio of 0.4%, 0.8% and 1.2% (by volume). Compressive strength, apparent porosity, bulk density, ultrasonic pulse velocity (UPV), X‐ray diffraction (XRD) and scanning electron microscope (SEM) analysis of GPC samples were carried out comparatively. The inclusion of GS6 fibre enhanced the compressive strength thanks to fibre surface being covered by geopolymer gel and the strong adhesion between GS fibre and geopolymer matrix. SEM images of fibre reinforced GPC (FRGPC) also confirmed the experimental findings, which were attributed to improvement in compressive strength. Regardless of the fibre type, the maximum compressive value strength was obtained from GPC specimens with 0.4% fibre and then decreased. Higher fibre inclusions led to poor compaction, workability issues and inhomogeneous fibre dispersions. A very good relation (R2 = 0.98) was acquired between UPV and compressive strength values of GPC/FRGPC samples.

The effect of polypropylene fiber on the mechanical properties between hybrid fiber geopolymer concrete and geopolymer concrete in elevated temperature

This paper has influence on discovering the behavior of hybrid polypropylene fiber reinforced geopolymer concrete under constant and elevated temperature with the purpose to determine the mechanical properties of the material. While the expertise and acquaintance with concrete behavior under constant temperature are well known, the behaviour under elevated temperature has to be seriously explored. This study objectives is to match between the mechanical properties of unburnt and burnt fiber reinforced geopolymer concrete. This study uses experimental investigation. Compression and splitting tensile tests were conducted on the 150 mm cilinder mold. Meanwhile, flexural tension test was conducted on 100 mm x 100 mm x 450 mm rectangular mold. The result of both materials, without set fire to and with set fire to, are analyzed. The gained findings for burnt material are the compression test value cut down, otherwise, the splitting tensile test and flexural tensile strength grade increase.

Post-fire investigation on the mechanical properties and physical characteristics of fibre-reinforced geopolymer concrete

PurposeThe construction industries at present are focusing on designing sustainable concrete with less carbon footprint. Considering this aspect, a Fibre-Reinforced Geopolymer Concrete (FGC) was developed with 8 and 10 molarities (M). At elevated temperatures, concrete experiences deterioration of its mechanical properties which is in some cases associated with spalling, leading to the building collapse.Design/methodology/approachIn this study, six geopolymer-based mix proportions are prepared with crimped steel fibre (SF), polypropylene fibre (PF), basalt fibre (BF), a hybrid mixture consisting of (SF + PF), a hybrid mixture with (SF + BF), and a reference specimen (without fibres). After temperature exposure, ultrasonic pulse velocity, physical characteristics of damaged concrete, loss of compressive strength (CS), split tensile strength (TS), and flexural strength (FS) of concrete are assessed. A polynomial relationship is developed between residual strength properties of concrete, and it showed a good agreement.FindingsThe test results concluded that concrete with BF showed a lower loss in CS after 925 °C (i.e. 60 min of heating) temperature exposure. In the case of TS, and FS, the concrete with SF had lesser loss in strength. After 986 °C and 1029 °C exposure, concrete with the hybrid combination (SF + BF) showed lower strength deterioration in CS, TS, and FS as compared to concrete with PF and SF + PF. The rate of reduction in strength is similar to that of GC-BF in CS, GC-SF in TS and FS.Originality/valuePerformance evaluation under fire exposure is necessary for FGC. In this study, we provided the mechanical behaviour and physical properties of SF, PF, and BF-based geopolymer concrete exposed to high temperatures, which were evaluated according to ISO standards. In addition, micro-structural behaviour and linear polynomials are observed.

Modeling of strength properties of Geo polymer concrete beam

Concrete is most versatile material used in construction process. Portland cement is most used material in India for upcoming innovative projects. Cement replacement process is being used by adding Ground granulated blast furnace slag (GGBS) and FLYASH. Continuous use of lime stone for manufacturing of cement will affect the environment. Manufacturing of cement produces carbon dioxide and it effects the environment and human health. In this study cement has been replaced with GGBS and FLYASH to reduce the carbon dioxide. Geo polymer concrete is presently used to construct huge structures. The aim of present study was to measure the strength properties of concrete made of several compositions of geo-polymer and model the strength parameters using different mathematical equations. Compression strength increased from 17.25 MPa to 37.25 MPa from in the time period of 7 days to 28 days for conventional specimen. In case of GPC samples the compression strength increased from 21.4 to 43.6 MPa for the same period of time. For HFRGPC5 the compression strength has been increased from 26.02 MPa to 52.36 MPa within the same time period. Compression strength results indicated that Hybrid Fiber Reinforced Geo polymer Concrete 5 has better strength properties compared to all other compositions of Hybrid Fiber Reinforced Geo polymer Concrete. Polynomial model fitted the best with highest R square value compared to linear and exponential equations.

A Review on Fresh, Hardened, and Microstructural Properties of Fibre-Reinforced Geopolymer Concrete

Alternative eco-friendly and sustainable construction methods are being developed to address growing infrastructure demands, which is a promising field of study. The development of substitute concrete binders is required to alleviate the environmental consequences of Portland cement. Geopolymers are very promising low-carbon, cement-free composite materials with superior mechanical and serviceability properties, compared to Ordinary Portland Cement (OPC) based construction materials. These quasi-brittle inorganic composites, which employ an "alkali activating solution" as a binder agent and industrial waste with greater alumina and silica content as its base material, can have their ductility enhanced by utilising the proper reinforcing elements, ideally "fibres". By analysing prior investigations, this paper explains and shows that Fibre Reinforced Geopolymer Concrete (FRGPC) possesses excellent thermal stability, low weight, and decreased shrinking properties. Thus, it is strongly predicted that fibre-reinforced geopolymers will innovate quickly. This research also discusses the history of FRGPC and its fresh and hardened properties. Lightweight Geopolymer Concrete (GPC) absorption of moisture content and thermomechanical properties formed from Fly ash (FA), Sodium Hydroxide (NaOH), and Sodium Silicate (Na2SiO3) solutions, as well as fibres, are evaluated experimentally and discussed. Additionally, extending fibre measures become advantageous by enhancing the instance's long-term shrinking performance. Compared to non-fibrous composites, adding more fibre to the composite often strengthens its mechanical properties. The outcome of this review study demonstrates the mechanical features of FRGPC, including density, compressive strength, split tensile strength, and flexural strength, as well as its microstructural properties.

Prediction of compressive strength fiber-reinforced geopolymer concrete (FRGC) using gene expression programming (GEP)

This paper examines the rapidly evolving fiber-reinforced geopolymer composites (FRGC), focusing on the material and geometrical properties of construction fibers and the mechanisms involved in fiber-binder interaction at different curing conditions to determine the compressive strength. To eliminate expensive and time-consuming experimental techniques, soft computing techniques, i.e., gene expression programming (GEP), were used to develop an empirical equation for the prediction of compressive strength (fc′) of FRGC. The database consists of 393 experimental datasets to determine the (fc′) with several curing days to train the GEP models. The mixtures contain the most influential parameters such as fly ash (FA), silica fume (SF), metakaolin (MK), ground granulated blast furnace slag (GGBS), aggregate (AG), sodium hydroxide (SH), sodium metasilicate (SM), alkaline activator (AAK), binder (B), superplasticizer (SP), water (W), curing age (CA), length (L), diameter (D), aspect ratio (AR), density (ρ), tensile strength (ft′), and fiber (F) to determine the fc′. The database is separated into two parts, 70% is used for training, and 30% is for testing. Several linking functions, chromosomes, head size, and genes have been undertaken to determine the optimal results. Expression trees (ETs) are developed and presented in the discussion section, and create the empirical equation from it. Determining the performance of the best model, MSE, RMSE, and R2 are calculated for the FRGC mixture to confirm the GEP models under various situations. Additionally, sensitivity analysis (SA) is also introduced to see the FRGC of each input parameter’s contribution to the prediction of fc′.

Development of Ca-rich slag-based ultra-high-performance fiber-reinforced geopolymer concrete (UHP-FRGC): Effect of sand-to-binder ratio

In this study, a Ca-rich slag-based Ultra-High-Performance Fiber-Reinforced Geopolymer Concrete (UHP-FRGC) with a high compressive strength of over 150 MPa and high tensile ductility (strain energy density of over 50 kJ/m3) was developed. To optimize its mechanical properties, various silica sand-to-binder (S/B) ratios ranging from 0.16 to 0.8 were considered. Geopolymeric and C(A)SH gels were produced simultaneously, and silica fume helped to increase the strength through its filler effect and accelerated the reactivity of the slag. The packing density and compressive strength of the UHP-FRGC increased with increasing S/B ratio up to 0.8, and the highest packing density and compressive strength of 0.78 and 160.7 MPa, respectively, were achieved at an S/B ratio of 0.8. Improved tensile performance of UHP-FRGC with an increase in the S/B ratio was also observed, and the best tensile performance resulted in a tensile strength of 10.3 MPa, strain capacity of 0.833%, and strain energy density of 55.0 kJ/m3. Although both the complementary energy (J’b) and crack tip toughness (Jtip) increased with the S/B ratio, the rate of increase of Jtip was much greater than that of J’b, causing a decreased pseudo strain-hardening (PSH) index. The lowest energy PSH index of 8.23 was thus obtained in the UHP-FRGC with an S/B ratio of 0.8, which provided the best tensile performance. Therefore, no correlation between the strain-hardening performance and PSH index was observed for UHP-FRGC with steel fibers.

Behaviour of Hybrid Fiber Reinforced Geopolymer Concrete Beams under Flexural Loading

This paper presents the behaviour of GPC beams with and without fiber under flexural loading. The work is presented in two parts. In the first part tests were conducted for mechanical properties of plain and hybrid fiber reinforced Geopolymer concrete to determine maximum strength characteristics of concrete. In the second part of the program two types of under-reinforced beams were cast with plain GPC and hybrid fiber reinforced GPC (HFRGPC) and tested under two points loading. The percentage of tensile rebar ratio is kept constant for two types of beams. The hybrid fiber reinforced GPC is prepared with 1.5%(1%Steel+0.5% Polypropylene) of fibers and used to cast the under reinforced beams .The cast specimens are tested after a specified curing period to determine first crack load, ultimate load, load-deflection behaviour and crack patterns. The results are compared with the theoretical values. From the test results, the fiber volume fraction has a compelling effect on the cracking load, ultimate load, crack pattern and failure mode. The flexural behaviour of the beams including the induced cracks, failure pattern, load deflection capacity and ductility index were compared. The ductility index of hybrid fiber reinforced beams is greater than that of GPC beams. The HFRGPC beams showed superior performance than that of GPC beams for parameters considered in this experimental study.

Comparative study of compressive strength of novel steel fiber reinforced geopolymer concrete and conventional concrete

The main aim of this study is to quantify the influence of steel fiber on the compressive strength of the geopolymer concrete. There were 2 groups taken for this study and a total of 18 samples were prepared per group. Many samples were calculated using clinical software by adopting the values from the old research papers. Different types of materials and apparatus were used during the preparation and testing of the samples. SPSS software, version 21 has been used to carry out the independent sample T-test. The mean compressive strength of geopolymer concrete with novel steel fibre sample is 32.2 N/mm2and the mean compressive strength of conventional concrete sample is 28.15 N/mm2. Independent samples t-test is performed to analyse the results. The significance(p) of the events was 0.115 (p > 0.05). It doesn't show any significant difference. The standard deviation of steel fiber reinforced geopolymer concrete was 75.73658. From this experimental study, it is concluded that the steel fiber reinforced M20 grade geopolymer concrete has a greater compressive strength than conventional concrete.

Carbonation performances of steel fiber reinforced geopolymer concrete

Steel fiber reinforced geopolymer concrete (SFRGC) shows excellent mechanical properties comparable to steel fiber reinforced concrete. However, research on the durability of SFRGC is scarce. This paper presents the carbonation performances of SFRGC, including the carbonation depth and strength variation during carbonation. The results show that the permeability and carbonation depth of SFRGC are close to those of plain geopolymer concrete (GC). Their carbonation depths are much deeper than those of cement concrete because of the lower alkali content of the geopolymer matrix. Carbonation hardly influences the final flexural strength of plain GC, but the flexural strength of SFRGC declines significantly during carbonation because of the decrease in steel fiber-geopolymer matrix bond strength. The scanning electron microscope results show that the failure mode in uncarbonated SFRGC specimens is fiber rupture, while in carbonated SFRGC specimens, fiber pullout is the failure mode. These findings suggest that using SFRGC in the atmosphere is not recommended.