Macro Fibers Research Articles

Modeling and optimization of acantilevered energy harvester partially covered by a macro fiber vomposite patch

Piezoelectric energy harvesters (PEH) are recognized as smart structural devices, offering researchers an innovative approach to estimate the energy harvested from real vibration sources. This work presents linear analytical methods for predicting the energy harvested from an unimorph cantilevered beam with a proof mass, with a substrate partially covered by a Macro Fiber Composite (MFC) patch. In order to enhance a PEH that can generate more density of electrical power, a new framework for MFC harvesters with discontinuous geometries using Euler-Bernoulli assumptions is proposed. The length of the harvester can be divided into three parts of uniform beams followed by applying appropriate continuity conditions. Mixing rules are used to derive the equivalent properties of the MFC patch which is considered as five layers. The active layer contains a piezoceramic macro fibers embedded within an epoxy matrix, which is fully covered by electrode and Kapton layers. The excitation of the system is assumed to be at its base. The proposed method is validated through experimental comparison issued from the literature. The results indicate that the location of the MFC patch has a significantly affect to the density of electrical power, the optimal resistance and the natural frequencies.

Pullout behavior of recycled macro fibers embedded in ultra-high performance seawater sea-sand concrete

Recently, an eco-friendly ultra-high performance concrete (UHPC) has been developed using seawater, sea-sand (UHPSSC) and the recycled macro fiber (REF) processed from waste wind turbines, which could be easily available in remote islands and address the corrosion issue of concrete structures with steel reinforcements. The interface bond of the UHPSSC/macro fiber are lack of investigation and a significant factor influencing the tensile characteristics of macro fiber reinforced UHPSSC. In the present study, the pullout test of the single macro fiber was conducted to investigate the average bond behavior of such interface. The test variables included the macro fiber width (4, 6, and 8 mm), the embedded length (5, 10, and 15 mm), and the type of matrix. Then, the local bond-slip relationship at the fiber/UHPSSC interface was obtained by finite element analysis (FEA) to provide a more precise display of interface bond mechanisms. The results revealed that the bond of UHPSSC/macro fiber was stronger with increased fiber embedded length and width due to the greater frictional interactions and better overall integrity. Additionally, the FEA method proposed here to obtain the local bond-slip relationship was reliable and effective. This study can serve as a basis for further research on the tensile properties of UHPSSC reinforced with macro fibers.

Rubber concrete reinforced with macro fibers recycled from waste GFRP composites: Mechanical properties and environmental impact analysis

With the rapid growth of the automotive industry, a huge amount of tires have been produced, which inevitably led to the accumulation of scrap tires. A typical disposal routine is using scrap tires as a partial substitute for fine aggregate in concrete, producing so-called rubber concrete. However, the detrimental effects of rubber particles on concrete properties have been identified, which, to some content, hinders their broader application. The discrete fiber addition is shown to be effective in minimizing this detrimental effect, and this paper has therefore attempted to introduce macro fiber produced from waste glass fiber reinforced polymer (GFRP) into the rubber concrete system. Three series of specimens for compression, splitting, and flexural testing were tested. The test variables include concrete type (i.e., normal concrete, rubber concrete, and modified rubber concrete); and macro fiber content (i.e., 0–2 %). In addition, the inverse analysis is performed to transform the flexural test response into the tensile constitutive law of the fiber-reinforced concrete (FRC). The test results revealed macro fibers have little effect on the compressive strength of normal concrete and rubber concrete and a detrimental effect on that of modified rubber concrete. Incorporated fibers notably improve the splitting and flexural performance of normal concrete and rubber concrete. In addition, the cost and environmental impact analysis revealed that the addition of recycling products increases the concrete cost and results in a maximum reduction of carbon emissions by 17.3 % and embodied energy emissions by 80 %.

Analysis of synergistic effect of bending energy absorption capacity of fiber reinforced concrete based on fiber distribution characteristic

Macro fibers could contribute to absorb energy through fiber sliding, which significantly enhance the energy absorption capacity of concrete beams. In this research, the synergistic effect of macro steel fibers and polypropylene (PP) fibers on the energy absorption capacity of concrete under bending is under investigated. The three-point bending test is adopted to compared the residual flexural strength and energy absorption capacity of fiber reinforced concrete (FRC) beams. Besides traditional Load-deflection curves, the energy absorption-crack mouth opening displacement (CMOD) curves are adopted to reflect the toughness of FRC beams. The synergistic effect of steel fibers and PP fibers on the residual flexural strength and energy absorption capacity is evaluated. A linear function is proposed to describe the relationship between energy absorption and CMOD for FRC beams. In addition, fiber distribution on cracking surface of FRC beams is analyzed through fiber distribution density and fiber spacing to explain the synergistic effect. Experimental results indicate that the behaviors of FRC beams, that is, residual flexural strength and energy absorption, are improved by adding macro fibers, in particular macro steel fibers. Besides, the relationship between energy absorption and CMOD of FRC beams can be fitted very well by the linear function. The slope of the energy absorption and CMOD relationship is adopted to analyze the contribution of macro fibers to energy absorption. The uniformity of fiber distribution is improved by increasing of fiber dosage for SFRC and PFRC beams. The hybrid use of macro steel fibers and PP fibers demonstrates a positive synergistic effect on the energy absorption capacity and flexural strength of concrete. The improved fiber spacing and fiber distribution density of hybrid fiber on cracking surface contribute to the positive synergistic effect observed in hybrid fiber reinforced concrete (HyFRC) beams.

Effects of Macro Fibers on Crack Opening Reduction in Fiber Reinforced Concrete Overlays.

Macro fibers have been extensively used in the construction of various concrete structures, including bridges, dams, tunnels, industrial floors, and pavements. However, their effectiveness in reducing crack opening widths in concrete pavements has not been fully explored. This study aims to delineate the role of fibers by identifying the optimal types and volumes for effectively controlling cracks in concrete pavement structures, particularly in thin overlays. The research investigates how different fiber types, such as synthetic and steel, and their respective volumes can mitigate crack propagation in concrete overlays. Additionally, it evaluates the performance of fiber-reinforced concrete overlays compared to conventional dowel bar systems in terms of crack width reduction and overall pavement durability. The findings aim to provide specific design criteria for incorporating macro fibers in concrete overlays to enhance structural integrity and longevity.

Analysis Of Macro Fibre Concrete Reinforcement For Sustainable Infrastructure Development

Sustainable infrastructure development in Indonesia currently still uses concrete as its material, as the use of concrete increases, there are more and more efforts to improve concrete's capabilities or reduce its weaknesses. Many innovations have been carried out, such as adding additional materials and one of them from plastic bottle waste, because the development of flexible infrastructure is one of the key factors in responding to the challenges faced by the global community today. So research was carried out to increase the maximum load of concrete using a mixture of macro fibers derived from plastic bottle waste. The research method used was an experimental method at the Civil Engineering Structure Laboratory, Faculty of Engineering, Islamic University of Kalimantan MAB Banjarmasin. From the results of research testing the maximum load of concrete with variations in macro fibers from plastic waste using cube specimens measuring 15 cm x 15 cm, and cylinders measuring 15 cm x 30 cm, the load increased with a value of 446.66 Kn to 456.66 kN for cube specimen and 210 kN to 303.33 kN for cylindrical specimen.

Bond behavior between recycled macro fibers and ultra-high-performance concrete matrix: Tests and property characterization

A green and cost-efficient ultra-high-performance concrete (UHPC) has been proposed using discrete macro fibers recycled from waste glass fiber reinforced polymer (GFRP). The tensile properties of such composites are significantly affected by the macro fiber/UHPC bond properties. However, there is very little work characterizing the bond properties of the macro fiber/UHPC interface. Furthermore. lack of study focused on the methods for macro fiber surface treatment and their effects on macro fiber/UHPC interfacial bonding. Therefore, the present study first carried out pullout tests in two series consisting of 128 pullout specimens. Series 1 aimed to characterize the bond behavior of the macro fiber/UHPC interface, while Series 2 aimed to investigate the effect of surface-modifying agents on macro fiber/UHPC interfacial bonding. The results demonstrated that the bond strength increased from 19.3 to 20.9 MPa when the embedded length of the 8 mm-wide fiber increased from 5 to 10 mm. The modification of neutral Nano SiO2 (NNS) enhanced the bond strength by up to 20.5 %, while alkaline Nano SiO2 (ANS) and silane coupling agent (SCA) showed a negative effect on bond strength. Then, the shear-lag theory was utilized for predicting the pull force-slip curves of the fibers embedded in UHPC, and then the bond parameters of the interfaces were obtained through an inverse analysis. A good agreement is exhibited with integral absolute error (IAE) from 4.5 % to 10.5 % between predicted results and test results.

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.

Utilizing sugar factory lime waste and crumb rubber for sustainable Ultra-High-Performance Concrete

Ultra-High-performance Concrete (UHPC) offers significant advancements in construction due to its superior strength and durability. However, its traditional formulation demands extensive cement use, leading to high costs and adverse environmental impacts. This research explores the feasibility of repurposing lime waste, a by-product of sugar production, as a substitute for cementitious materials in UHPC, while also examining the use of crumb rubber powder as a complementary filler within the UHPC matrix. Glass, steel, and synthetic macro fibers are also added to improve the ductility of the concrete mix. A series of mechanical tests are conducted to evaluate the performance of the developed concrete. The results are compared with those of conventional cement and other cement substitutes. It is found that replacing 10 % of cement with lime waste and rubber powder produces the optimal UHPC mix, with 104 MPa compressive strength, 7.1 MPa bending strength, 5.8 MPa tensile strength, and 32.8 GPa modulus of elasticity. Moreover, steel fibers are the best reinforcement option, as they significantly improve the ductility and malleability of the concrete, achieving 13,456 J rupture energy and 17.4 MPa bending strength. However, a microstructure analysis reveals that the cement substitutes cause a slight deterioration in the concrete quality, but this is compensated by the benefits of the fibers. It is also shown that the use of lime waste and rubber powder reduces the carbon footprint and the cost of UHPC, making it a more sustainable and economical choice for construction materials. Therefore, it is concluded that the use of lime waste and rubber powder as cement substitutes in UHPC is a feasible and beneficial strategy for developing environmentally friendly UHPC with enhanced mechanical properties. This study contributes to the advancement of eco-conscious UHPC and opens new avenues for future research.

Experimental investigation on bond-slip performance and damage evolution mechanism of deformed reinforcing bar embedded in steel polyvinyl-alcohol hybrid fiber high performance concrete after high temperature

Hybrid Fiber High Performance Concrete (HFHPC) utilizes the synergistic effects of macro and micro fibers at different stages, which can effectively improve its mechanical properties, fracture toughness, ductility, and impact resistance after high temperature. The bonding between steel bars and hybrid concrete is a fundamental prerequisite for ensuring that these two materials with completely different mechanical properties work together. In order to study on bond-slip performance and damage evolution mechanism of deformed reinforcing bar embedded in steel-polyvinyl-alcohol (S-PVA) hybrid fiber high performance concrete (HFHPC) after high temperature, a total of 75 specimens were designed and manufactured by selecting volume fraction of steel fiber and PVA fiber and dosing of slag powder as the orthogonal test factors, and the central pull-out test were completed after exposure to room temperature, 200℃, 400℃, 600℃, and 800℃. The experimental results indicate that the bonding failure mode of HFHPC specimens all showed steel bar pull-out failure after high temperature, and the bond stress-slip curve can be divided into 4 stages: elastic rise stage, nonlinear rise stage, plastic degradation stage, and residual stage. As the temperature increases, the bonding strength of HFHPC specimens gradually decreases and the peak slip gradually increases. The addition of hybrid fibers can significantly improve the bonding ductility and energy dissipation capacity of deformed reinforcing bar embedded in S-PVA HFHPC after high temperature. When the temperature is below 200℃, the bonding strength damage rate of S-PVA HFHPC specimens is relatively slow; when the temperature exceeds 200℃, the bonding strength damage rate of S-PVA HFHPC specimens increases.

Behaviour of FRC Beams with Different Combination of Fibers

The use of fibers in reinforced concrete (RC) beams mainly improves both the bearing capacity and the cracking control. In this way, positive effects on the service life of RC structures can be expected. In this paper, the fiber influence on the flexural behaviour of RC beams with different longitudinal reinforcement ratios (0.5% ≤ρs≤ 1.2%) is analyzed by testing small-scale RC beams. Concretes incorporating 0, 25 and 50 kg/m3 of steel, 6 and 12 kg/m3 of glass macro fibers, and 5 and 10 kg/m3 of polymer macro fibers were studied. Crack and deflection control, as well as bearing capacity and crack localization were evaluated for a broad range of fiber-reinforced concrete (FRC) toughness. It is verified that fibers, in the longitudinal reinforcement ratio considered, improve the bending behaviour at serviceability limit state (SLS) and ultimate limit state (ULS) of RC beams, without limiting the structure ductility. It was also confirmed the philosophy of the fib Model Code 2010, such that FRC can be considered as a composite material where performance parameters govern its mechanical behaviour. Finally, the several data available allowed to deeply analyze fib Model Code 2010 formulations (mean crack spacing and flexural bearing capacity) and to propose modifications where needed.

Predicting compressive strength of fiber-reinforced coral aggregate concrete: Interpretable optimized XGBoost model and experimental validation

The addition of macro and micro fibers can enhance the compressive strength of fiber-reinforced coral aggregate concrete (FRCAC-CS). Traditional explicit models for FRCAC-CS suffer from shortcomings related to accuracy and generalization capabilities. To address this issue, a comprehensive database for FRCAC-CS was established by collecting 834 sets of experimental data from 15 literature sources. The hunger games search algorithm (HGS), sooty tern optimization algorithm, and whales optimization algorithm were used to optimize the hyperparameters of the XGBoost algorithm, resulting in optimized XGBoost models for FRCAC-CS. The performance of the prediction models was assessed through comparisons between predicted and actual values, model residual distribution, and performance evaluation metrics. Sensitivity analysis was conducted using the Shapley additive explanations method. Subsequently, 9 different mix proportions were formulated to validate the performance of the optimal model. The results suggest that the HGS–XGBoost model yields predictions that are closer to the actual values, exhibiting smaller mean and standard deviation in model residuals. The five major performance evaluation metrics, including RMSE, MSE, MAPE, MAE, and R2, for the HGS–XGBoost model are 0.91, 0.83, 2.35, 0.77, and 0.99, respectively, surpassing those of other models. Sensitivity analysis highlights the water–to–binder ratio and total aggregate content as the two most crucial factors among the mix components. Decreasing the water–to–binder ratio and the total aggregate content improves the FRCAC-CS. The experimental results from the 9 mix proportions demonstrate that the error between predicted and experimental values is below 7%, affirming the HGS–XGBoost model’s adequate accuracy and generalization capabilities for new datasets. This study introduces a novel AI-based prediction method for FRCAC-CS, establishing the groundwork for its potential application in reef construction.

Novel UHPC with calcium-oxide-activated materials and fibres: engineering properties and sustainability evaluation

Novel ultra-high-performance concretes (UHPCs) made with calcium-oxide-activated materials (CAM), modified synthetic macro (MSM) fibres, glass fibres and steel fibres were developed. The mechanical and durability properties of UHPC-CAM specimens made with the different fibre types were tested and compared. The microstructure of the samples was examined using scanning electron microscopy (SEM). The environmental impacts of the mix designs were assessed using the Impact 2002+ method, a life cycle assessment tool. The results showed that the UHPC-CAM made with glass or MSM fibres had a high compressive strength (>110 MPa) and improved ductility. These specimens also had low water absorption and high electrical resistance, indicating low corrosion risk. SEM analyses showed that the MSM fibres created a denser geopolymer matrix than the glass fibres. The UHPC-CAM was found to have a lower environmental impact than conventional UHPC in terms of human health, ecosystem quality, carbon dioxide footprint and use of resources. MSM fibres were determined to be the most eco-friendly fibres for UHPC-CAM production.

Effect of Macro Fibers on the Permeability and Crack Surface Topography of Layered Fiber Reinforced Concrete.

This paper describes the effects of macro fibers on permeability and crack surface topography of layered fiber-reinforced concrete (FRC) specimens with different layering ratios under uniaxial tensile load. The crack permeability of layered FRC specimens is investigated by a self-designed permeability setup. The topographical analysis of crack surfaces is investigated by a custom-designed laser scanning setup. The results show that when the fiber volume content and layering ratio of the FRC layer are constant, the tensile toughness of layered FRC specimens depends on the proportion of steel fiber in macro fibers, and with an increase in the proportion of steel fiber, the tensile toughness of layered FRC specimens increases. For the layered FRC specimens, the crack permeability is much lower than that of the normal concrete (NC) specimen. A significant positive synergistic effect on crack impermeability can be achieved by the combination of steel fiber and polypropylene fiber in the SF80PP2.3 specimen. The crack surface roughness parameter (Rn) values of the NC layer in layered FRC specimens are all higher than those of the NC specimen, and the crack surface Rn of the FRC layer in layered FRC specimens is higher than that of the unlayered FRC specimens. This can effectively increase the head loss of cracks and reduce the crack permeability of layered FRC specimens.

The splitting tensile strength and impact resistance of concrete reinforced with hybrid BFRP minibars and micro fibers

Basalt fiber reinforced polymer (BFRP) minibar is a novel kind of macro fiber, which is high-performed, green and durable. This study aimed to use hybrid BFRP minibars and micro fibers to control cracks of concrete from micro size to macro size, ultimately improving the mechanical properties of concrete. The compressive strength, splitting tensile strength and impact resistance of concrete reinforced with hybrid BFRP minibars and various micro fibers were tested and evaluated. The micro fibers contained micro basalt fibers, polyvinyl alcohol (PVA) fibers and steel fibers. Test results showed that the hybrid fibers provided significantly positive synergistic effects on the impact resistance, compressive and splitting tensile strength of concrete. Micro fibers improved the microcrack resistance capacity of concrete that increased with micro fiber content and modulus, but most of fractured during the development process of microcracks owing to their tiny size, showing little contribution to macrocrack resistance. BFRP minibar showed the pull-out failure, and the force preventing BFRP minibar from pullout bridged macrocracks, improving the macrocrack resistance capacity of concrete., but they seldom improved the microcrack resistance capacity of concrete because of its large size. Hybrid fibers improve the sustained resistance to crack during the whole crack development process owing to the synergistic contribution of hybrid fibers. Thereby, the concrete reinforced with hybrid 1.5% BFRP minibars and 0.75% micro steel fibers showed the highest compressive strength, splitting tensile strength and final-fracturing impact life under the failure probability of 30%, which were 22% 29% and 415% higher than those of concrete with mono 1.5% BFRP minibars. The method, which is that using hybrid macro fibers and micro fibers with high modulus and proper content to reinforce concrete, supports for further improving the mechanical properties of concrete in practice.

Bond behavior of the FRP grid-concrete interface with geopolymer mortar as an adhesive

This study conducts an investigation into the effect of the geopolymer mortar (GPM) thickness on the bond behavior of the FRP grid-concrete interface. Eighteen specimens were tested under the single-lap shear loading to evaluate the effect of the mortar thickness (8/10/15/20/25 mm) and macro fiber reinforcement from failure mode, load response, strain distribution, and bond stress distribution. The study further assessed the applicability of existing calculation models for the FRP grid-concrete interface. The results indicate that the ultimate load initially increased and then decreased as the mortar thickness increased, and the macro fiber reinforced mortar enhanced the ultimate load. However, mortar thickness variation and macro fiber reinforcement had little effect on the failure mode, strain distribution, and bond stress distribution, while lager thickness and macro fibers significantly reduced crack occurrences. Additionally, existing models for the FRP sheet-concrete interface tended to underestimate the effective bond length and interface fracture energy of the FRP grid-concrete interface. Regression analysis, based on existing models, enabled the development of effective bond length and bond-slip relationships, showcasing satisfactory accuracy.

Small-scale laboratory tests for quantifying aggregate interlocking in short-panelled concrete pavements

In the present study, a simple and reliabe small-scale laboratory test to assess the performance of aggregate interlocked joints in short-panelled concrete pavements in terms of LTE is proposed. In the proposed test method, conventional standard flexural strength test beam specimens (100×100× 500mm) are used for understanding the performance of aggregate interlocking of PQC mix specimens prepared using coarse aggregates of different NMAS and with addition of both micro and macro fibers. The test setup is also modelled in ANSYS FE software. The experimentally obtained LTE is compared with the LTE obtained from the FE model. The field FWD test is conducted for validation. The relative movement is determined from FWD test, and corresponding LTE is determined using the LTE and RM relationship obtained from experimental results using the proposed test apparatus. There exists good linear fit between the LTE determined using proposed test and field FWD test results.

Shrinkage cracking and mechanical properties of cementitious composites produced with multiwall carbon nano tubes and different types of polypropylene fibres

This study was conducted to experimentally demonstrate the control the nano-, micro- and macro-scale cracking in cement-based composites by using nano-, micro- and macro-scale fibres. While micro, macro and hybrid system polypropylene (PP) fibres were used in concrete designs, micro-scale PP and multi-walled carbon nano tubes (MWCNT) were utilized in mortar mixtures. The progression of the cracks was monitored in accordance with a well-known standard and also with a modified method which enabled the investigation of plastic and restrained shrinkage. Fracture energy, flexural strength, compressive strength, modulus of elasticity and ultrasonic pulse velocity of the samples were also determined as the mechanical properties of the composites. Results showed significant improvements in the reduction of cracks, especially with hybrid fibres system.

Damage constitutive model of polypropylene-fibre-reinforced recycled aggregate concrete

Adding polypropylene fibre (PPF) to recycled aggregate concrete (RAC) not only improves performance but also has economic benefits. The effects of single-blend and double-blend micro- and macro-PPFs in RAC specimens were studied. Micro- and macro-PPFs were used to design and produce 30 groups of PPF-reinforced RAC specimens with 0%, 25% and 50% coarse aggregate (CA) substitution rates. Controlling the fibre mixing proportions, the stress–strain curve, elastic modulus, peak strength, peak strain and acoustic emission amplitude–frequency extremum (AFE) of each group of specimens were obtained. The elastic modulus and peak stress of specimens without PPFs decreases gradually with an increase of the CA substitution rate. However, there was a certain increase in elastic modulus and peak stress when PPFs were added. A damage constitutive model for PPF-reinforced RAC was established. By fitting this model, it was found that although the elastic modulus and peak stress of the RAC specimens increased by a certain extent, the fitting parameters of RAC were greater than those of ordinary concrete and the RAC post-peak strength was lower. The evolution law of acoustic emission AFE of PPF-reinforced RAC was studied. It was found that the cumulative AFE of RAC with PPF was larger, indicating that the PPFs limited crack propagation and increased the fracture energy.

Effect of incorporating recycled macro fibres on the properties of ultra-high-performance seawater sea-sand concrete

Ultra-high-performance concrete (UHPC) is an ideal material for constructing marine infrastructures, but faces obstacles such as limited local raw materials (i.e., freshwater and river-sand) and corrosion of steel reinforcement. Non-metallic reinforcement is preferable for reinforcing marine UHPC, especially when seawater and sea-sand are used to develop ultra-high-performance seawater sea-sand concrete (USSC). Recently, the authors' group proposed a cost-efficient UHPC reinforced with discrete macro fibres mechanically processed from waste glass fibre-reinforced polymer (GFRP) composites. This present study aimed to explore the potential application of incorporating macro fibres in USSC. A series of tests were conducted to investigate the fundamental properties of macro fibre reinforced USSC with the examined variables including the content (0 %, 2 %, 4 %, and 6 %) and lengths (30 mm and 60 mm) of macro fibres. Comparisons were made between USSC and UHPC with river-sand and freshwater (UTRC), which were both reinforced with macro fibres. The results revealed that incorporating macro fibres in USSC improved the compressive toughness index (CTI) and flexural toughness by up to 84.00 % and 40.15 times respectively, but decreased the workability and compressive strength by up to 42.22 % and 21.45 % respectively. The effect of incorporating macro fibres on the properties of USSC was more prominent than that of its counterpart of UTRC. A theoretical model was then developed for predicting the flexural toughness of various concrete with macro fibres based on the regression analysis on the available test results.