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Magnesium oxychloride cement (MOC) is often recognized as an eco-friendly cement and has found widespread application in various sectors. However, research on its resistance against elevated temperatures including fire is very limited. This paper thoroughly investigated the mechanical performance of fibre reinforced MOC-based cementitious composite (FRMOCC) at ambient and elevated temperatures. A recently developed water-resistant MOC was used as the base matrix which was further reinforced using hybrid basalt and polypropylene fibres at various proportions, and a systematic study on the effect of fibre dosage on compressive and tensile strength of FRMOCC was conducted. The specimens were exposed to elevated temperatures ranging from 200 to 800 °C; mechanical performance and phase composition from a microscale study were analysed. The findings revealed that compressive strength, with the increase in temperature, substantially decreased, with values of 30–87% at 400 °C and over 95% at 800 °C. Specimens with 1.5% basalt and 0.5% PP fibre showed the least reduction possibly due to the vacant channels created as a result of the melting effect of PP fibres. Tensile strength was also completely lost at 600 °C and the specimens suffered substantial mass loss exceeding 30% at this temperature, indicating significant matrix decomposition. Additional analysis using X-ray diffraction (XRD) and scanning electron microscope (SEM) revealed the decomposition stages of the matrix and highlighted the instability of the main hydration phases of FRMOCC at elevated temperatures. [ABSTRACT FROM AUTHOR]

Many research works have already been made and are still in progress on metallic fibres, as their incorporation reduces the brittleness of the concrete and improves its resistance to the impact and crack propagation. But the use of such non-metallic fibres may induce corrosion which is a major problem to be addressed from the durability aspect. To overcome this problem, in the present research work, a non-metallic hybrid fibre combination was investigated with synthetic fibres like polypropylene and abaca fibres. Also, rather than using conventional cementitious materials such as silica fume, fly ash, and ground granulated blast furnace slag, a new generation of ultra-fine material namely alccofine was used as a partial replacement for the cement by 15%. Abaca fibre was utilised in a constant addition of 0.5% and blended with polypropylene fibre in a range varying from 0% to 2% with an increment of 0.5%. The fresh properties of self-compacting concrete (SCC) in mono and hybrid fibres combinations were assessed through slump flow, J-ring, and V-funnel tests. Water absorption and sorptivity tests were conducted to ensure the durability of the prepared mix. Further, impact tests were carried out on the prepared cylinder specimens to check the capability of the mix with the non-metallic hybrid combination. The main objective here was to check whether a high-strength durable SCC could be achieved using non-metallic fibres and natural fibres. From the obtained experimental results, it was observed that 15% alccofine as a partial substitute to the cement with the addition of 0.5% of abaca fibre and 2% of polypropylene fibre to SCC performed better than the control SCC.

With the aid of an electronic universal testing machine and a scanning electron microscope, uniaxial compression tests and microscopic examinations of cemented tailings backfill with mixed fibers were carried out in order to investigate the impact of mixing steel fiber (SF) and polypropylene fiber (PF) on the static mechanical properties and failure mode. The findings demonstrate that; the inclusion of hybrid fiber has a substantial impact on the failure mode of the backfill; the CTB is mostly damaged by single bevel shear, displaying an evident brittle failure;the SP-FRB is primarily damaged by relatively minor secondary cracks due to the bridging and crack-resisting action of internal fibers; and the specimen is fractured as a whole,demonstrating an obvious ductile deformation; The addition of hybrid fiber can increase the filler s uniaxial compressive strength,but there is a maximum amount that should be used. The stress-strain curves of both CTB and SP-FRB contain four stages: pore compaction, linear elastic deformation, plastic yield,and post-failure. The results of the microscopic tests indicate that the initial pore size and number inside the filler are significant factors in its failure. Steel fiber and polypropylene fiber can both maintain high integrity inside the filler and prevent crack expansion through adhesion with the matrix and their own fatigue fracture, respectively. [ABSTRACT FROM AUTHOR]

Magnesium oxychloride cement (MOC) is often recognized as an eco-friendly cement and has found widespread application in various sectors. However, research on its resistance against elevated temperatures including fire is very limited. This paper thoroughly investigated the mechanical performance of fibre reinforced MOC-based cementitious composite (FRMOCC) at ambient and elevated temperatures. A recently developed water-resistant MOC was used as the base matrix which was further reinforced using hybrid basalt and polypropylene fibres at various proportions, and a systematic study on the effect of fibre dosage on compressive and tensile strength of FRMOCC was conducted. The specimens were exposed to elevated temperatures ranging from 200 to 800 °C; mechanical performance and phase composition from a microscale study were analysed. The findings revealed that compressive strength, with the increase in temperature, substantially decreased, with values of 30–87% at 400 °C and over 95% at 800 °C. Specimens with 1.5% basalt and 0.5% PP fibre showed the least reduction possibly due to the vacant channels created as a result of the melting effect of PP fibres. Tensile strength was also completely lost at 600 °C and the specimens suffered substantial mass loss exceeding 30% at this temperature, indicating significant matrix decomposition. Additional analysis using X-ray diffraction (XRD) and scanning electron microscope (SEM) revealed the decomposition stages of the matrix and highlighted the instability of the main hydration phases of FRMOCC at elevated temperatures.

This research develops a sustainable Engineered Cementitious Composites (ECC) with reduced cement usage by incorporating high volume fly ash (HVFA) and silica fume, along with the novel application of nanocellulose (NC)- a plant-based nanomaterial- and hybrid fibres to achieve high strength and ductility simultaneously. 12 mixes were developed including three base ECC mixes with 1.5 % polyethylene (PE) and 0.5 % steel fibres with varying proportions of fly ash and silica fume (1.2:0–1:0.2) and nine NC reinforced ECC mixes with varying dosages of NC (0.15 %, 0.2 %, 0.25 % by weight). The effect of fly ash/silica fume ratio and NC on mechanical properties was investigated through compressive and uniaxial tensile tests. Scanning electron microscope (SEM) and differential scanning calorimetry (DSC) techniques were utilized to gain insights into the HVFA and NC matrix systems as well as the mechanisms of NC and hybrid fibres. Results showed that reducing the fly ash/ silica fume ratio increased strength but reduced tensile strain. Incorporating NC improved strength across all mixes, irrespective of fly ash/silica fume content, with the mix containing 0.2 % NC showing the highest improvement. This novel ECC is anticipated to offer a sustainable and high-performance material solution for engineering structures. • Development of green hybrid PE-Steel fibre reinforced ECC using nanocellulose and high-volume fly ash. • Significantly reduced usage of cement with simultaneous enhancement in strength and strain capability. • Effect of blends of fly ash, silica fume, and NC on mechanical performance is analysed. • 0.2 % nanocellulose is found optimum for superior compressive and tensile performance. • Nanocellulose induced internal curing effect and led to enhanced degree of hydration. [ABSTRACT FROM AUTHOR]

On reducing greenhouse gas emissions by the cement industry, geopolymer with an amorphous polymer form was the best alternative. Geopolymer concrete (GPC) was weak in impact strength, brittle, ductile, and energy absorption than conventional cement concrete. Various property fibres with the capacity to improve the aforementioned properties of GPC can be added. Polypropylene fibre with low elastic modulus and waste tire rubber fibre with high elastic modulus was used in this research to improve energy absorption and impact strength. Different modulus fibres such as polypropylene and rubber was added by 0%, 0.5%, 1%, 1.5% and 2% of volume fraction. The effects of adding individual fibres on the mechanical property of eco-friendly geopolymer concrete were studied. In addition, the influence of hybrid fibres on the mechanical features of low-calcium geopolymer concrete was assessed. The research results revealed that the hybridization of 0.5% of polypropylene fibre and 0.5% of rubber fibre showed better performance and achieved maximum strength in all mechanical features such as compressive, flexural, and splitting tensile behaviour. Meanwhile, the optimum hybrid fibres increased the mechanical features by 23.9%, 12.0%, and 15.2%, respectively, at the 28 days of curing ages compared to geopolymer concrete without fibres.

Discrete short steel fibres were proposed to be mixed with concrete for arresting cracks and enhancing the post-cracking resistance. It has been proven in previous tests that spiral steel fibres possessed markedly higher bonding to concrete matrix, leading to significantly improved performance of steel fibre reinforced concrete (SFRC) in terms of crack controllability, impact resistance, deformability and energy absorption capability. However, at the initial stage of cracking, SFRC reinforced with spiral fibres has relatively lower resistance to crack opening as compared to that reinforced with other types of steel fibres because of spiral shape stretching. To overcome this shortcoming, in the present study, short hooked-end steel fibres that exhibit high pull-out resistance at the crack initiation stage were mixed with spiral steel fibres in the normal-strength concrete matrix. A total volume fraction of 1% of hybrid steel fibres was mixed to cast SFRC specimens. With various mix ratios between spiral and hooked-end fibres considered, five batches of SFRC specimens were tested. Uniaxial compressive tests and four-point bending tests were carried out to compare the mechanical properties of SFRC materials with hybrid fibres while three-point bending tests on SFRC structural beams under static, drop-weight impact and post-impact static loading tests were conducted to investigate the structural performances. An equal dosage of hooked-end and spiral fibres was found to outperform other blend proportions to provide synergetic reinforcement to concrete matrix in terms of post-cracking resistance, energy absorption capacity and post-impact performance. [ABSTRACT FROM AUTHOR]

Hybrid fibre-reinforced concrete with a low-fibre content (HFLC) is an effective strategy for promoting the engineering applications of fibre-reinforced concrete (FRC). However, there is a lack of research on the evolution of fracture process zone (FPZ) and fracture parameters in HFLC. In this study, the fracture properties of HFLC, remarkably layered hybrid fibre-reinforced beams (LHFB) were investigated using a three-point bending test on notched beams. The load-crack mouth opening displacement curves, fracture toughness, and fracture energy of the HFLC were comprehensively evaluated for different macrofibre contents and microfibre types. Qualitative and quantitative characterisation of the FPZ was conducted. Finally, a bilinear softening constitutive curve suitable for HFLC was determined. The results indicate that a slight increase in the content of macro-hooked-end steel fibres (MHSF) in the low-fibre content hybrid system can significantly enhance the fracture performance and deformation resistance of concrete. However, the specimens exhibited similar failure modes, and before the peak load, the FPZ length increased sharply. The critical FPZ length of the SF0.5 series was, on average, 70 % higher than that of the SF0.3 series. The average unstable toughness and fracture energy of SF0.5 were 342 % and 48 % higher, respectively, than those of SF0.3. Notably, the effect of MHSF content was greater than that of the microfibre type. Furthermore, only the LB-MSSF showed an improvement in fracture performance, whereas the layered beam unexpectedly reduced the peak load of the specimen. Therefore, their performance should be carefully evaluated when using layering methods. • The fracture process and fracture parameters of HFLC and HFLB were investigated. • Qualitative and quantitative characterization of the fracture process zone was conducted. • The peak load of the specimen could be reduced when using the layering method. • The parameters of bilinear softening model suitable for HFLC were determined. [ABSTRACT FROM AUTHOR]

Beam–column joints are extremely vulnerable to lateral and vertical loads in reinforced concrete (RC) structures. This insufficiency in joint performance can lead to the failure of the whole structure in the event of unforeseen seismic and wind loads. This experimental work was conducted to study the behaviour of ternary blend geopolymer concrete (TGPC) beam-column joints with the addition of hybrid fibres, viz., steel and polypropylene fibres, under reverse cyclic loads. Nine RC beam-column joints were prepared and tested under reverse cyclic loading to recreate the conditions during an earthquake. M55 grade TGPC was designed and used in this present study. The primary parameters studied in this experimental investigation were the volume fractions of steel fibres (0.5% and 1.0%) and polypropylene fibres, viz., 0.1 to 0.25%, with an increment of 0.05%. In this study, the properties of hybrid fibre-reinforced ternary blend geopolymer concrete (HTGPC) beam-column joints, such as their ductility, energy absorption capacity, initial crack load and peak load carrying capacity, were investigated. The test results imply that the hybridisation of fibres effectively enhances the joint performance of TGPC. Also, an effort was made to compare the shear strength of HTGPC beam-column connections with existing equations from the literature. As the available models did not match the actual test results, a method was performed to obtain the shear strength of HTGPC beam-column connections. The developed equation was found to compare convincingly with the experimental test results. [ABSTRACT FROM AUTHOR]

Geopolymer concrete is one of the innovative eco-friendly materials that has gained the attention of many researchers in the sustainable development of the construction industry. The primary objective of this experimental investigation is to study the flexural behaviour of the ternary blend geopolymer concrete (TGPC) with various proportions of hybrid fibres. In this study, 27 reinforced concrete beams were cast with a TGPC grade of M55 and tested under monotonic loading conditions. The specimens were beams of length 1200 mm, depth of 150 mm, and width of 100 mm. Crimped steel (metallic) fibres and polypropylene (non-metallic) fibres were used in hybrid form to study the effect on the TGPC beams under flexure. The volume fractions of steel fibres were varied up to 1% with an increment of 0.5%, and polypropylene fibres varied from 0.1% to 0.25% with an increment of 0.05%. The test results were analysed based on the first crack load, ultimate load, load-deflection behaviour, energy absorption capacity, moment-curvature relationship, and ductility behaviour and compared with TGPC specimens without fibres. The experimental study reveals that the TGPC is one of the best alternatives for conventional cement concrete. The addition of hybrid fibres potentially improves the flexural properties of TGPC to a great extent. The test results showcased that the HTGPC with 1% steel and 0.1% polypropylene fibres exhibited better flexural properties than the other combinations of hybrid fibres considered in this study. Additionally, an effort was made to develop a model to estimate the flexural strength of TGPC with hybrid fibres, and the predicted values were found satisfactorily with the test results. [ABSTRACT FROM AUTHOR]

On reducing greenhouse gas emissions by the cement industry, geopolymer with an amorphous polymer form was the best alternative. Geopolymer concrete (GPC) was weak in impact strength, brittle, ductile, and energy absorption than conventional cement concrete. Various property fibres with the capacity to improve the aforementioned properties of GPC can be added. Polypropylene fibre with low elastic modulus and waste tire rubber fibre with high elastic modulus was used in this research to improve energy absorption and impact strength. Different modulus fibres such as polypropylene and rubber was added by 0%, 0.5%, 1%, 1.5% and 2% of volume fraction. The effects of adding individual fibres on the mechanical property of eco-friendly geopolymer concrete were studied. In addition, the influence of hybrid fibres on the mechanical features of low-calcium geopolymer concrete was assessed. The research results revealed that the hybridization of 0.5% of polypropylene fibre and 0.5% of rubber fibre showed better performance and achieved maximum strength in all mechanical features such as compressive, flexural, and splitting tensile behaviour. Meanwhile, the optimum hybrid fibres increased the mechanical features by 23.9%, 12.0%, and 15.2%, respectively, at the 28 days of curing ages compared to geopolymer concrete without fibres. [ABSTRACT FROM AUTHOR]

The mechanical properties of hybrid fibre (polypropylene and wood)-reinforced expanded polystyrene (EPS) lightweight aggregate concrete was studied under various sand contents. Cubic and prismatic compression tests were carried out, through which the basic mechanical properties and stress-strain curves of the specimens were obtained. Moreover, the microstructures of the fibre-reinforced concrete with different sand proportions were analysed via scanning electron microscopy (SEM). The test results showed that as the sand proportion increased, the cubic compressive strength and prismatic compressive strength of the EPS lightweight aggregate concrete increased. The optimal slump was obtained when the sand ratio was 25%, after which the slump declined. The EPS lightweight aggregate concrete exhibited obvious elastoplastic behaviour during compression, and the corresponding stress-strain curve could be divided into four stages: the elastic stage, strengthening stage, softening stage and collapse platform stage. Moreover, based on the test results and the damage theory and considering the coupling relationship between plasticity and damage, a damage constitutive model was proposed for hybrid fibre-reinforced EPS lightweight aggregate concrete under uniaxial compression.

In this paper, it is proposed to study the static flexural performance of hybrid (glass and steel) fiber reinforced M30 grade self-compacting concrete (SCC) beams made with glass fiber reinforcement polymer (GFRP) re-bars. Nan Su mix design approach is adopted to develop the M30 grade plain SCC (PSCC) mixes. Glass fibre SCC (GFRSCC), steel fibre SCC (GFRSCC) and hybrid fibre SCC (HFRSCC) mixes are prepared using the optimum dosages of glass (0.05%) and steel fibres (1%) by volume fraction. HFRSCC reinforced beams of size 1200 *200*150 mm will be casted with steel and GFRB rebars and tested to study the flexural properties such as ultimate flexural strength, load at first crack, deflection at the center, crack width and crack patterns. For the above fibred beams, load-deflection relations will be established. The HFRSCC beam made with GFRP rebars have the load carrying capacity 37.03% more than HFRSCC beam made with steel rebars. The deflection for the HFRSCC beam made with GFRP rebars is 61.52% more than beam made with steel rebar HFRSCC beam made with GFRP rebars increases the load at first crack, ultimate flexural strength, and deflection at the centre at failure and the crack width for same HFRSCC beam made with steel rebars

The need to develop sustainable concrete in the civil infrastructure industry increases day by day, resulting in new eco-friendly materials such as geopolymer concrete. Geopolymer concrete is one of the eminent alternatives to conventional concrete for sustainable development by reducing the carbon footprint. Ternary blend geopolymer concrete (TGPC) is a sustainable and environmentally friendly concrete produced with three different source materials to form a binder. The main advantage of TGPC is that it possesses densely packed particles of different shapes and sizes, which results in improved properties. This paper deals with the experimental investigations to evaluate the durability properties of plain and hybrid fibre reinforced TGPC. The durability of concrete is defined as the ability to withstand a safe level of serviceability and different environmental exposure conditions without any significant repair and rehabilitation throughout the service life. Conventional concrete is vulnerable to cracking due to its low tensile and durability properties. The TGPC considered in this work consists of fly ash, GGBS and metakaolin as source materials, selected mainly based on the material’s silica and alumina content, shape, size, and availability. The grade of concrete considered was M55. The main variables considered in this study were the proportions of crimped steel fibres (Vf), viz., 0.5% and 1% and proportions of polypropylene fibres (Vp)viz., 0.1%, 0.15%, 0.20% and 0.25%. The durability properties like water absorption, sorptivity, resistance to marine attack, acid attack, sulphate attack, and abrasion were studied in this investigation. The experimental test results were compared with the requirements provided in the standard/literature and found to be well within limits. The study also indicates that the inclusion of fibres in a hybrid form significantly improves the durability parameters of TGPC. The TGPC with 1% steel fibre and 0.15% polypropylene fibre performs better than the other combination of fibres considered in this experimental investigation. [ABSTRACT FROM AUTHOR]

This study presents the development of an environmentally sustainable hybrid polyethylene (PE)-steel fibre reinforced engineered cementitious composites (ECC) to achieve enhanced compressive performance at elevated temperature. Utilizing a unique blend of industry by-products—ground granulated blast furnace slag (GGBFS), dolomite powder, and fly ash, with supplementary cementitious materials exceeding 50% replacement level, the developed ECC achieves remarkable improvement in compressive strength, both at ambient and elevated temperature conditions. A total of 340-cylinder specimens were tested to analyse the compressive properties after exposure to 20–800 °C, and the effect of different binders, fibre ratio on the residual compressive behaviour was investigated. Additionally, effects of the critical fire test parameters such as pre-drying and cooling treatment were also studied. The research findings indicate that incorporating high-volume GGBFS blends significantly improved the compressive performance of the ECC irrespective of the type of test parameters. Notably, a specific blend comprising of GGBFS, fly ash (GGBFS:fly ash = 1:0.2) and dolomite (15% by binder weight) demonstrated 138 MPa strength at room temperature and at least 75% and 45% strength retention at 600 °C and 800 °C, respectively. This was significantly higher than the values reported in literatures (∼48% at 600 °C and ∼12% at 800 °C) for similar type of ECC. The study also highlights the impact of sudden cooling in water and confirms the occurrence of both thermal shock and rehydration through microstructural analysis. Environmental impact analysis was also conducted to demonstrate the low carbon emission of the developed ECC. [Display omitted] • Compressive properties of PE-steel fibre ECC at elevated temperatures are studied. • Effect of binder materials, type of cooling and pre-drying treatment is analysed. • Compressive strength retained by more than 45% at 800 °C with GGBFS and dolomite use. • Water cooling is found to cause both rehydration and thermal damage. • Effect of pre-drying treatment is negligible on the compressive performance. [ABSTRACT FROM AUTHOR]

Magnesium oxychloride cement (MOC) as a green cement has superior mechanical properties such as high strength and quick gain of early strength, however the inherent brittleness has limited its applications where ductility is crucial. To enhance the strength and ductility, a novel hybrid fibre-reinforced MOC-based composite (FRMOC) is developed for the first time using polyethylene (PE) fibres and basalt fibres (BF) to reinforce the MOC. A systematic investigation of the effect of fibre dosage on the flowability, rheological properties, compressive strength, and tensile properties of the developed FRMOC is conducted in this study. The results revealed that the addition of fibre reduces flowability while increasing the yield stress and plastic viscosity. The 1-day compressive strength of the FRMOC reached 68.2–85.4% of the corresponding value at 28 days, demonstrating its high early strength characteristic. The mix with 1.25% PE and 0.75% BF exhibited the maximum compressive strength at all curing ages. All the mixes consistently demonstrated excellent tensile strength and tensile strain capability (ductility), with the tensile strength and tensile strain capacity of 10.95 MPa and 4.41% achieved for the mix of 2% PE fibre, and 8.49 MPa and 2.43% for the mix of 1.25% PE and 0.75% BF respectively. Moreover, a decline in strength characteristics and strain capacity was observed as BF percentages increased. Scanning electron microscope (SEM) analysis was further employed to investigate the morphological changes in the FRMOC matrix at the microscale to discover the fibre reinforcing mechanism. • Hybrid fibre reinforced MOC (FRMOC) with enhanced strength and ductility is developed. • FRMOC demonstrates high-early-strength characteristic. • Rheological, physical, and mechanical properties were evaluated. • 1.25% PE and 0.75% BF-reinforced FRMOC exhibited maximum tensile strength and strain capacity. • Microstructural analysis is performed to analyse the morphological alterations. [ABSTRACT FROM AUTHOR]

A new hybrid solid-phase microextraction coating, [Ba(5,5ʹ-dcbipy)(µ-H2O)2 (H2O)2]n and polypyrrole, has been prepared using an electrochemical method. The fibre was well characterised and showed superior properties. The fibre showed excellent thermal stability, adherently and chemical stability which were suitable for extracting analytes from harsh media and desorbing them in a high thermal inlet of a GC. Four phthalate esters were extracted with this fibre and then analysed via GC-flame ionisation detector. Salt concentration, temperature and time of extraction were optimised. The detection limits and linear ranges were 0.077–0.25 μg L−1 and 0.125–500 to 0.25–125 μg L−1, respectively. The intra-day and inter-day relative standard deviations were found to be 6.9–9.4 and 2.9–23.4%, respectively. The results then were compared with other works. Phthalates in two different aqueous samples of food products were successfully analysed with the proposed method. [ABSTRACT FROM AUTHOR]

This study presents a detailed experimental investigation on the effects incorporating non-metallic fibers in hybrid form in self-compacting concrete (SCC). In this regard SCC was prepared with Alccofine and Metakaolin as partial replacement for cement in 15% and 20% respectively along with the hybrid fibre combinations namely abaca fibres (0.25%, 0.5% & 0.75%), polypropylene fibres (0.5%, 1%, 1.5% & 2%) and glass fibres (0.5%, 1%, 1.5%, & 2%). The fresh properties of SCC with and without hybrid fibre combinations were assessed through the standard tests such as slump flow, J ring and V-funnel tests. The conventional mechanical tests such as compressive strength test, split tensile strength test and flexural strength test were performed at 7 and 28 days. The experimental results reveal that the fresh properties of SCC were highly influenced by alccofine and Metakaolin adopted in this research. Furthermore, that the hybrid combination of abaca with polypropylene and glass fibres improved the mechanical properties of SCC and in particular the mix with 1% glass fibre and 0.25% Abaca fibre had shown better flexural and tensile strength behaviour. Microstructure analyses were also done to confirm the improvement in mechanical properties. The Scanning Electron Microscope images of the mix with 1% glass fibre and 0.25% abaca fibre showed less voids presence and presence of more hydrated components conveying that the usage of hybrid fibres had restricted the propagation of cracks there by reducing the percentage of voids and the use of metakaolin and alcofine helping in forming hydrated components at earlier stage leading to better strength.

The increasing need for eco-friendly green building and creative passive design technology in response to climatic change and global warming issues will continue. However, the need to preserve and sustain the natural environment is also crucial. A building envelope plays a pivotal role in areas where the greatest heat and energy loss often occur. Investment for the passive design aspect of building envelopes is essential to address CO 2 emission. This research aims to explore the suitability of using integral-monolithic structural insulation fibre-reinforced lightweight aggregate concrete (LWAC) without additional insulation as a building envelope material in a high-rise residential building in the different climatic zones of the world. Polypropylene and steel fibres in different dosages were used in a structural grade expanded clay lightweight aggregate concrete. Physical and thermal properties of fibre reinforced structural LWAC, normal weight concrete (NWC) and bricks were measured in the lab. The Autodesk@Revit-GBS simulation program was implemented to simulate the energy consumption of a 29-storey residential building with shear wall structural system using the proposed fibre-reinforced LWAC materials. Results showed that energy savings between 3.2% and 14.8% were incurred in buildings using the fibre-reinforced LWAC across various climatic regions as compared with traditional NWC and sand-cement brick and clay brick walls. In conclusion, fibre-reinforced LWAC in hot-humid tropical and temperate Mediterranean climates meet the certified Green Building Index (GBI) requirements of less than 150 kW∙h∙m−2. However, in extreme climatic conditions of sub-arctic and hot semi-arid desert climates, a thicker wall or additional insulation is required to meet the certified green building requirements. Hence, the energy-saving measure is influenced largely by the use of fibre-reinforced LWAC as a building envelope material rather than because of building orientation. [ABSTRACT FROM AUTHOR]

Polymer matrix composites (PMCs) are widely used materials in aerospace structures, boat hulls, automotive parts, etc. Since the progression of PMCs, a single fibre composite lags the addition of one or more fibres prepared as a hybrid composite which can be used to enhance their mechanical properties. Hybrid bamboo/glass fibres as the alternative replacement for polyester composites have been fabricated with ±60° orientation, and coconut shell powder in micro and nanosized particles was added as the filler materials. Mechanical properties such as tensile, flexural, and impact strength, hardness number, and fatigue behaviour were investigated. The fractured surfaces of the composites were observed by scanning electron microscopy analysis. The test results reveal that the bamboo fibres in combination with glass fibres show an enhancement in their mechanical properties like strength and stiffness, and are suitable for aerospace applications. [ABSTRACT FROM AUTHOR]

Abstract The aim of this research is to establish the fracture properties of high performance concrete (HPC) containing hybrid – basalt (B) and polypropylene (P) fibres. The experimental investigation consisted of tests on cubes, beams and notched prismatic specimens made of plain HPC and fibre reinforced HPC with 1% and 2% of basalt and/or polypropylene fibres. Extensive data on the compressive and tensile splitting strength, flexural behaviour, as well as fracture energy are determined and analyzed. The experimental investigations show that HPC with hybrid B/P fibres display a more ductile behaviour compared to that of plain HPC. The results of the bending tests revealed extended post-peak softening behaviour. The shape of the descending branch depended on the mechanical properties of the fibres, and volume content used. The results illustration the positive effect of high modulus basalt and low modulus polypropylene fibres on HPC fracture energy growth. Moreover the results indicate that a combination of fibres may contribute more effectively to increasing the flexural strength, flexural toughness and fracture energy than using a single type of fibre. [ABSTRACT FROM AUTHOR]

The increasing need for eco-friendly green building and creative passive design technology in response to climatic change and global warming issues will continue. However, the need to preserve and sustain the natural environment is also crucial. A building envelope plays a pivotal role in areas where the greatest heat and energy loss often occur. Investment for the passive design aspect of building envelopes is essential to address CO 2 emission. This research aims to explore the suitability of using integral-monolithic structural insulation fibre-reinforced lightweight aggregate concrete (LWAC) without additional insulation as a building envelope material in a high-rise residential building in the different climatic zones of the world. Polypropylene and steel fibres in different dosages were used in a structural grade expanded clay lightweight aggregate concrete. Physical and thermal properties of fibre reinforced structural LWAC, normal weight concrete (NWC) and bricks were measured in the lab. The Autodesk@Revit-GBS simulation program was implemented to simulate the energy consumption of a 29-storey residential building with shear wall structural system using the proposed fibre-reinforced LWAC materials. Results showed that energy savings between 3.2% and 14.8% were incurred in buildings using the fibre-reinforced LWAC across various climatic regions as compared with traditional NWC and sand-cement brick and clay brick walls. In conclusion, fibre-reinforced LWAC in hot-humid tropical and temperate Mediterranean climates meet the certified Green Building Index (GBI) requirements of less than 150 kW∙h∙m−2. However, in extreme climatic conditions of sub-arctic and hot semi-arid desert climates, a thicker wall or additional insulation is required to meet the certified green building requirements. Hence, the energy-saving measure is influenced largely by the use of fibre-reinforced LWAC as a building envelope material rather than because of building orientation.

Graphical abstract Highlights • The application of TPFM instead of MTPM caused an overestimation of the fracture toughness values. • Fibres did not have a meaningful effect on the occurrence of the probable kinked crack. • Short steel and macro-polypropylene fibers had a synergy impact on changing the fracture toughness. • Steel fibre was the most influential in bridging macro-cracks. Abstract In the present paper, the fracture behaviour of fibre-reinforced roller-compacted concrete (RCC) specimens are examined, with mono and hybrid fibre (different type and length). The modified two-parameter model (MTPM) was employed to calculate Mode I plain-strain fracture toughness which is able to take into account the possible crack deflection (kinked crack). The results showed that for a great amount of kinked angle, the application of the two-parameter model (TPFM) instead of MTPM cause to an overestimation of the fracture toughness values. Furthermore, the addition of fibres to the RCC mixture does not significantly affect the occurrence of the probable kinked crack during stable crack propagation. Based on three-point bending test results on notched beam, there is a positive synergy effect between short steel fibre and macro-polypropylene fibres on fracture toughness. In post-cracking extension, the large and strong steel fibre was the most influential in bridging macro-cracks. [ABSTRACT FROM AUTHOR]

In this paper, an experimental campaign was carried out to assess the impact failure strength of steel hybrid fibre reinforced concrete (SHFRC) subjected to freezing-thawing cycles in water containing 4.0% solution of NaCl. For this purpose, six different concrete mixtures were prepared by adding long and short steel fibres at 2.0% volume of concrete. The proportion of long to short straight steel fibres, also called as the hybrid fibre coefficient (HFC) of SHFRC, used in this study are 0, 0.25, 0.5, 0.75 and 1.0. All the specimens were subjected to freezing-thawing of 0, 25, 50, 75, 100, 125, 150, 175 and 200 cycles followed by impact test using pendulum impact device. Significant weight loss was observed in SHFRC specimens exposed to freezing-thawing cycles (0-200). Also, an analytical model was developed to assess the impact failure strength of SHFRC subjected to freezing-thawing cycles. The results revealed that when the number of freezing-thawing cycles were increased, the loss in weight of SHFRC specimens was increased and the impact failure strength of SHFRC specimens was decreased. The impact failure strength of SHFRC incorporating higher amount of long fibres was higher compared to short fibres, which implies that long fibre plays a predominant role in enhancing its impact failure strength. [ABSTRACT FROM AUTHOR]

The current version of the European standard for concrete structures gives tabulated data for the evolution of the mechanical properties of normal strength concrete subjected to elevated temperatures. However, the standard acknowledges the lack of sufficient data for the case of high strength concrete with limestone aggregate and there are no provisions for fibre reinforced concrete at high temperatures. This paper presents the experimental results obtained on six batches of normal and high strength fibre reinforced concrete made with limestone aggregates and tested after exposure to high temperatures. These results gave a good correlation with previous researches and equations were obtained to describe the evolution of the compressive strength and the flexural strength at elevated temperatures. Ductility was also measured in the flexural strength tests and results suggested that the use of steel fibres with higher aspect ratio may lead to lower ductility after exposure to temperatures higher than 650 °C. [ABSTRACT FROM AUTHOR]

• The mechanical property tests and test of GFRP reinforced hybrid fibre concrete short columns subjected to eccentric compression were conducted. • The cooperative effect of the GFRP reinforcement and the steel-PVA hybrid fibre concrete with different fibre ratios under eccentric loading was explored. • The addition of fibres can effectively prevent the crack generation and development and improve the bonding property between reinforcement bars and concrete. • The equation for the calculation of the ultimate compressive capacity of partial sections of eccentric columns is proposed. This paper presents the results of an experimental study carried out on the GFRP reinforced hybrid fibre concrete short columns subjected to eccentric compression. In this study, hybrid fiber-reinforced concrete was prepared in different volume ratios of hybrid fibers and the cooperative effect of the GFRP reinforcement and the steel-PVA hybrid fibre concrete with different fibre ratios under eccentric loading was explored. 10 GFRP reinforced hybrid fibre concrete short columns and 2 plain reinforced concrete short columns were tested to investigated their eccentric compressive properties. The tests results are presented in terms of failure modes, longitudinal reinforcement strain, concrete compressive strain and compressive load capacity of GFRP reinforced hybrid fibre concrete eccentrically compressed short columns. The results show that the concrete on the compressed side was crushed when the specimen under both the initial eccentricity of 50 mm and 100 mm the reinforcement were pulled on the tension side of specimen under a larger initial eccentricity of 100 mm. The addition of fibres can effectively prevent the crack generation and development and improve the bonding property between reinforcement and concrete. Besides, the addition of steel fibre contributes a better performance on the ultimate compressive capacity of specimen under a lager initial eccentricity with an optimal ratio of steel fibre at 1.4 %. PVA fibre effectively improve the ductility of the concrete, so that the hybrid fibre concrete elements remain relatively its integrity after failure. Finally, considering the effect of GFRP reinforcement and different ratios of steel fibre and PVA fibre on the compressive capacity of short concrete columns, the equation for the calculation of the ultimate compressive capacity of partial sections of eccentric columns is proposed, and a good agreement was observed between the tested and calculated value. [ABSTRACT FROM AUTHOR]

In order to improve the work behaviour of Plain Concrete (PC) of the shear keys in the immersed tunnel, a series of test programs consisting of direct shear, four points flexure, uniaxial tensile, uniaxial compression and splitting tensile tests were carried out to find the optimized mixture proportion of the fibres in Hybrid Fibre Reinforced Concretes (HFRC). The optimized unit weight of the hybrid fibres was obtained through the parametric studies on the improvements of different fibre contents on the mechanical properties of the HFRC, especially the shear strength and toughness. Additionally, the influences of incorporating hybrid fibres on flexure, direct shear toughness and residual load were also studied. The direct shear strength, shear toughness and residual shear load significantly increased due to the addition of steel fibres and basalt fibres. Through extensive experimental studies, the comparisons of the mechanical properties of the HFRC with different fibre content revealed that group C2 containing 180 kg/m 3 steel fibres and 4.5 kg/m 3 basalt fibres performed the best in terms of shear strength and toughness. The contributions of different types of fibres to the mechanical properties of HFRC were also investigated. The observations from the tests offer a practical guidance to concrete composites designers on the shear strength and shear deformation ability of different structures, especially for use in constructing the shear keys of an immersed tunnel. [ABSTRACT FROM AUTHOR]

In this paper, SiO 2 -TiO 2 hybrid fibres are fabricated using the electrospinning technique and Eu 3+ is successfully doped into the fibres through a simple sol-gel approach. The obtained SiO 2 -TiO 2 hybrid fibres are subjected to heat treatments at 600 °C, 800 °C and 1200 °C. The silica fibres subjected to a high temperature of 1200 °C become brittle and easily broken. Furthermore, the X-ray diffraction patterns demonstrate that crystalline titania forms in the SiO 2 -TiO 2 samples treated at 1200 °C, and excellent flexibility is demonstrated in the corresponding SiO 2 -TiO 2 non-woven mat. Moreover, the stress-strain curve demonstrates that the SiO 2 -TiO 2 mat heat-treated at 1200 °C exhibits typical elastic-plastic behaviour. Finally, the emission intensity of Eu 3+ of the SiO 2 -TiO 2 fibres is higher than that of the analogous SiO 2 fibres. This method can be adapted to fabricate inorganic-based hybrid fibres and will pave the way for the implementation of SiO 2 -TiO 2 non-woven mats in related research fields. [ABSTRACT FROM AUTHOR]