Search Results (20)

To investigate the potential of metakaolin (MK) (5%, 10%, 15%, and 20% substitution of cement mass) and basalt fibre (volume contents of 0.1%, 0.2%, and 0.3%) in recycled aggregate concrete (RAC) products, RAC’s mechanical properties were first assessed with a singular incorporation of MK. The findings demonstrated that adding 15% MK optimised the compressive strength and flexural strength of RAC (at the recycled aggregate replacement levels of 30%, 45%, and 60% by weight). An orthogonal test was conducted to investigate the synergistic effect of MK and basalt fibre (BF), with the recycled coarse aggregate (RCA) replacement rate (mass ratio of RCA to natural coarse aggregates), MK content (cement mass substitution percentage), and BF content (volume dosage) identified as the influencing parameters. The variance analysis reveals that the influence of the replacement ratio of RCA on compressive strength surpasses that of MK content, which in turn exceeds that of BF content. Conversely, as for the flexural strength, BF is substantially more effective than that of MK. A model test of RAC curbs was performed based on the ideal mix ratio suggested by the single mixing of MK and MK and BF compound mixing inside the orthogonal test. The results demonstrate that the RAC curbs, with an RCA replacement rate of 30%, display optimal mechanical properties when 15% MK and 0.2% BF are incorporated. This surpasses the performance of 15% MK alone and illustrates that the mix incorporation of MK and BF is superior to that of MK alone. Full article

This study investigates the flexural performance, tensile splitting strength, and fracture behaviour of self-compacting concrete (SCC) reinforced with polypropylene (PP) and basalt (BF) fibres. A total of eleven SCC mixtures with varying fibre types and volume fractions (0.025–0.25%) were tested at 7 and 28 days. In this study, the term high-performance concrete (HPC) refers to SCC mixtures with a 28-day compressive strength exceeding 60 MPa, as commonly accepted in European standards and literature. The control SCC achieved 68.2 MPa at 28 days. While fibre addition enhanced the tensile and flexural properties, it reduced workability, demonstrating the trade-off between mechanical performance and flowability in high-performance SCC. The experimental results demonstrate that both fibre types improve the tensile behaviour of SCC, with distinct performance patterns. PP fibres, owing to their flexibility and crack-bridging capability, were particularly effective at early ages, enhancing the splitting tensile strength by up to 45% and flexural toughness by over 300% at an optimal dosage of 0.125%. In contrast, BF fibres significantly increased the 28-day toughness (up to 15.7 J) and post-cracking resistance due to their superior stiffness and bonding with the matrix. However, high fibre contents adversely affected workability, particularly in BF-reinforced mixes. The findings highlight a dosage-sensitive behaviour, with optimum performance observed at 0.05–0.125% for PP and 0.125–0.25% for BF. While PP fibres improve crack distribution and early-age ductility, BF fibres offer higher stiffness and energy absorption in post-peak regimes. Statistical analysis (ANOVA and Tukey’s test) confirmed significant differences in the mechanical performance among fibre-reinforced mixes. The study provides insights into selecting appropriate fibre types and dosages for SCC structural applications. Further research on hybrid fibre systems and long-term durability is recommended. The results contribute to sustainable concrete design by promoting enhanced performance with low-volume, non-metallic fibres. Full article

This research paper employed novel sustainable alternative materials to reduce the environmental impact of thermoset/synthetic fibre composites. The effect of seawater hydrothermal ageing at 45 °C for 45 and 90 days on the physical and interlaminar fracture toughness (mode I and mode II) of a semi-unidirectional non-crimp basalt fibre (BF)-reinforced acrylic matrix and epoxy matrix composites was investigated. Optical and scanning electron microscopes were used to describe the fracture and interfacial failure mechanisms. The results show that the BF/Elium composite exhibited higher fracture toughness properties compared to the BF/Epoxy composite. The results of the mode I and mode II interlaminar fracture toughness values for the BF/Elium composite were 1280 J/m² and 2100 J/m², which are 14% and 56% higher, respectively, than those of the BF/Epoxy composite. The result values for both composites were normalised with respect to the density of each composite laminate. The saturated moisture content and diffusion coefficient values of seawater-aged samples at 45 °C and room temperature for the BF/Elium and BF/Epoxy composites were analysed. Both composites exhibited signs of polymer matrix decomposition and fibre surface degradation under the influence of seawater hydrothermal ageing, resulting in a reduction in the mode II interlaminar fracture toughness values. Enhancement was observed in mode I fracture toughness under hydrothermal ageing, particularly for the BF/Epoxy composite, due to matrix plasticisation and fibre bridging. Full article

Three-dimensionally printed cement-based composites emerge as a research hotspot in the fields of construction engineering in recent years. Current research primarily focuses on the reinforcement mechanisms of individually incorporated fibres, while a significant gap remains in the synergistic effects of hybrid fibre systems. This study investigates the effects of mono-doping (0.2 wt.% and 0.4 wt.% by the mass of the cement) and hybrid-doping (0.1 wt.% + 0.1 wt.% by the mass of the cement) with 3 mm polypropylene, basalt, and carbon fibres on the fresh-state properties and mechanical behaviours. Through quantitative characterisation of the flowability and mechanical performance of short-fibre-reinforced 3D-printed cementitious composites (SFR3DPC), coupled with comprehensive testing including digital image correlation, X-ray diffraction, and scanning electron microscopy, several key findings are obtained. The experimental results indicate that the addition of excess fibres reduces fluidity, which affects the mechanical performance and make the anisotropy of the composites more pronounced. While the single addition of 0.2 wt.% CF shows the most significant improvement in flexural and compressive strengths, the hybrid combination of 0.1 wt.% CF and 0.1 wt.% BF shows the greatest increase in interlayer bond strength by 26.7%. The complementary effect of the hybrid fibres contributes to the damage mode of the composites from brittle fracture to quasi-brittle behaviour at the physical level. These findings offer valuable insights into optimising the mechanical performance and improving defects of 3D-printed cementitious composites with short fibres. Full article

This research paper employed the recently developed Elium thermoplastic resin and basalt fabrics as an alternative to thermoset/synthetic fibre composites to reduce their environmental impact. Elium^® 191 XO/SA and Epoxy Prime^TM 37 resin were reinforced with mineral-based semi-unidirectional basalt fibre (BF). Physical, chemical, tensile, and flexural performance was investigated under the effect of hydrothermal seawater ageing at 45 °C for 45 and 90 days. The results show that the BF/Elium composite exhibited superior tensile and flexural strength, as well as good stiffness, compared with the BF/Epoxy composite. Digital images and scanning electron microscope images were used to describe the fracture and failure mechanisms. The tensile and flexural strength values of the BF/Elium composite were 1165 MPa and 1128 MPa, greater than those of the BF/Epoxy composite by 33% and 71%, respectively. The tensile and flexural modulus values of the BF/Elium composite were 44.1 GPa and 38.2 GPa, which are 30% and 12% greater than those of the BF/Epoxy composite. The result values for both composites were normalised with respect to the density of each composite laminate. Both composites exhibited signs of resin decomposition and fibre surface degradation under the influence of seawater ageing, resulting in a more recognisable reduction in flexural properties than in tensile properties. Full article

This study focuses on improving the recycled coarse aggregate (RCA) replacement ratio in recycled aggregate concrete products. First, the mix design and compressive performance of recycled aggregate concrete (RAC, RCA replacement percentages of 20%, 35%, and 50%) were evaluated using the monofactor analysis method and response surface methodology under three different conditions: single addition of nano-calcium carbonate (NC, dosages of 0.1%, 0.2%, and 0.3%), single addition of basalt fibre (BF, volume content of 0.1%, 0.2%, and 0.3%), and combined addition of both. The results show that the compressive strength of RAC at 7 and 28 days rises as the BF or NC content increases and then falls as the NC content increases. According to the sensitivity analysis, RAC’s compressive strength is significantly impacted by the replacement ratio of RCA, with NC having a more considerable effect on RAC’s 7-day compressive strength than BF, while BF affects the 28-day compressive strength more than NC does. Based on the desirability function, the ideal BF and NC content in RAC was optimised and confirmed by the compressive strength test. It demonstrates that the best compressive performance is achieved by RAC with 1% NC and 0.3% BF. Finally, concrete pavement brick models were created using the ideal mix proportion provided by the compressive strength test. The model compression test results show that RAC pavement bricks (RCA replacement ratio of 60%) with 1% NC and 0.3% BF had a 28d compressive strength of 5.7% and 15.8% higher than NAC and RAC pavement bricks, respectively. Full article

Recent investigations have shown that the mechanical and durability properties of recycled aggregate concrete can be enhanced using fly ash (FA) and structural fibres. However, the financial viability of combining these products in concrete has not yet been evaluated. Therefore, this study assessed the long-term cost-effectiveness of using recycled concrete aggregates (RCA), FA, and basalt fibres (BF) simultaneously in high-rise reinforced concrete buildings exposed to corrosive environments. A life cycle cost analysis was conducted using five variables, two design alternatives, and twelve design scenarios. The analysis followed ISO 15686–5:2017 using a discount rate of 0.5% and a construction-to-material cost ratio of 150%. The components considered in the life cycle cost model included materials, construction, maintenance, and disposal. The results demonstrated that employing RCA, FA, and BF in combination in concrete buildings located near the ocean achieved approximately 21% cost savings compared to buildings made with conventional materials over a lifespan of 50 years. The maintenance component exhibited the most significant cost savings, with an average reduction of about 76% in the maintenance costs for all buildings utilising RCA, FA, and BF. The sensitivity analysis revealed that the proposed building with RCA, FA, and BF remained more cost-effective than the conventional concrete building, even with an increasing RCA-to-natural-aggregate price ratio, construction-to-material cost ratio, and increasing the discount rate to 200%, 250%, and 10%, respectively. Full article

The interfacial transition zone (ITZ) is the weakest phase in concrete, characterised by higher porosity and being prone to microcrack formation. Additionally, the ITZ is created when dispersed fibre reinforcement is present. Although fibres improve flexural strength, they can negatively impact other properties. This research investigates the ITZ of fibre-reinforced concrete where macro-basalt fibres (BFs) and oil shale ash (OSA), as an SCM, were used with the aim of modifying the properties of concrete, enhancing the ITZ, and reducing its carbon footprint. Six different concrete mixes with OSA doses between 10% and 30% and a constant BF dose of 8.0 kg per 1 m³ of concrete were prepared and tested. The ITZ was analysed with SEM images and verified through its mechanical properties. The results showed that the presence of OSA improved bonding and densified the microstructure of the paste, especially in the ITZ, resulting in a nearly constant flexural strength at up to a 20% replacement and only a 6.7% decrease in compressive strength while reducing the global warming potential by 19.24 kg CO₂ equivalent in the mix with 10% OSA replacement. Higher replacement ratios had a negative impact on the mechanical properties, as the OSA had not reacted entirely and served partly as an inert filler. Full article

Process-induced defects during thermoforming are widespread problems in laminate manufacturing. The aim of this study is to describe the effects of holding time and pressure on several properties of the manufactured laminate. A design of experiments is performed, followed by an analysis of variance to examine significant effects. Subsequently, a regression model is created to predict the laminate’s properties, which is also validated. A significant interaction between holding time and pressure is determined for the resulting tensile strength and elongation at break with a p-value of $1.52·{10}^{-16}$ and $0.02$, respectively. The highest values of tensile strength and elongation at break are found for low settings of holding time and pressure. The fibre volume fraction is not affected by the process parameters. As holding time and pressure increase, significant fibre misalignment takes place, leading to a decrease of the mechanical properties. The regression model corresponds well with the validation and a tensile strength of 1049 MPa with an elongation at break of $2.3\%$ is reached. Full article

Incomplete data indicate that coal gangue is accumulated in China, with over 2000 gangue hills covering an area exceeding 200,000 mu and an annual growth rate surpassing 800 million tons. This accumulation not only signifies a substantial waste of resources but also poses a significant danger to the environment. Utilizing coal gangue as an aggregate in the production of coal-gangue concrete offers an effective avenue for coal-gangue recycling. However, compared with ordinary concrete, the strength and ductility of coal-gangue concrete require enhancement. Due to coal-gangue concrete having higher brittleness and lower deformation resistance than ordinary concrete, basalt fibre (BF) is a green, high-performance fibre that exhibits excellent bonding properties with cement-based materials, and polypropylene fibre (PF) is a flexible fibre with high deformability; thus, we determine if adding BF and PF to coal-gangue concrete can enhance its ductility and strength. In this paper, the stress–strain curve trends of different hybrid basalt–polypropylene fibre-reinforced coal-gangue concrete (HBPRGC) specimens under uniaxial compression are studied when the matrix strengths are C20 and C30. The effects of BF and PF on the mechanical and energy conversion behaviours of coal-gangue concrete are analysed. The results show that the ductile deformation of coal-gangue concrete can be markedly enhanced at a 0.1% hybrid-fibre volume content; HBPRGC-20-0.1 and HBPRGC-30-0.1 have elevations of 53.66% and 51.45% in total strain energy and 54.11% and 50% in dissipative energy, respectively. And HBPRGC-20-0.2 and HBPRGC-30-0.2 have elevations of 31.95% and 30.32% in total strain energy and −3.46% and 28.71% in dissipative energy, respectively. With hybrid-fibre volume content increased, the elastic modulus, the total strain energy, and the dissipative energy all show a downward trend. Therefore, 0.1% seems to be the optimum hybrid-fibre volume content for well-enhancing the ductility and strength of coal-gangue concrete. Finally, the damage evolution and deformation trends of coal-gangue concrete doped with fibre under uniaxial action are studied theoretically, and the constitutive model and damage evolution equation of HBPRGC are established based on Weibull theory The model and the equation are in good agreement with the experimental results. Full article

Cement production is a major source of carbon dioxide pollution. An environmentally friendly concrete needs to be developed in order to overcome the adverse environmental impacts of cement production and the continuing depletion of natural resources. Paper waste (hypo sludge) from the paper industry is becoming a challenge due to its extensive area requirements for disposal and continually increasing adverse environmental effects. To reduce paper waste and pollution, it might be beneficial to use it as hypo sludge in concrete mixes. In the present investigation, hypo sludge was used as a partial replacement in varied proportions (5, 10, 15, 20, 25, and 30%) of cement in concrete of M30 grade to be assessed. Styrene–butadiene rubber (SBR) latex and basalt fibre (BF) were added to hypo sludge concrete to improve its durability and post-cracking behaviour. From the test results, the optimum dosage of hypo sludge, basalt fibre, and SBR latex was found to be 15%, 0.3%, and 10%, respectively. From the mechanical properties testing compared with the control concrete, latex-added hypo sludge basalt fibre showed an increase in compressive strength by 17.08%, flexural strength by 14.55% and tensile strength by 14.29%. Microstructural results showed that SBR latex created greater consistency in the interaction of the concrete stages. Results of the tests indicate that the performance of the concrete in terms of its strength was improved by partially replacing the cement in the concrete with hypo sludge. Full article

Short basalt fibres (BFs) have recently gained significant interest in the building materials sector due to their superior mechanical characteristics and cheaper manufacturing cost than other fibre types. Drying shrinkage and the early-age cracking of concrete are the root cause of many durability issues in the long run. Including small dosages of fibres within concrete composites has been shown as an effective technique to minimise drying shrinkage rates and reduce the crack widths developed due to plastic shrinkage cracking. Nevertheless, limited research studies have investigated the influence of short and long BFs with different dosages on the drying shrinkage rates and early-age cracking of geopolymer composites. In the present study, self-compacting geopolymer concrete (SCGC) using fly ash and slag as the binder is mixed with anhydrous sodium metasilicate powder as an alkali-activator. The study aims to investigate the influence of short (12 mm), long (30 mm) and hybrid-length (1:3 (short/long)) BFs with 1%, 1.5% and 2% dosages on the drying shrinkage properties and plastic shrinkage cracking of SCGC. The study results showed that adding BFs to SCGC reduces the drying shrinkage rates compared to plain SCGC, and SCGC reinforced with a 2% dosage of hybrid-length BFs recorded the lowest drying shrinkage rate. Two methods were used to measure crack widths: manual measurement (crack width gauge) and image analysis. No plastic shrinkage cracks were identified in mixes reinforced with 12 mm (1.5% and 2% dosages), 30 mm and hybrid-length BFs. Full article

In order to solve the limitation of graphite tailings in improving the toughness of cement-based materials, this paper aims to study the effect of basalt fibres (BF) on the mechanical properties of graphite tailings cement mortar (GTCM). Basic physical and mechanical tests such as fluidity, water absorption, surface water content, flexural strength, compressive strength and modulus of elasticity were conducted on basalt fibre-reinforced graphite tailings cement mortar (BFR-GTCM), and combined with microscopic tests such as scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and mercury intrusion porosimetry (MIP) for the enhancement mechanism were deeply analysed. The results show that 0.3% BF and 20% GT are the optimal doping amounts for the mechanical response of BFR-GTCM, which especially significantly improves the flexural and crack resistance. In addition, the synergistic effect of basalt fibres and graphite tailings optimizes the spatial structure and pore distribution of the cement matrix and promoted the hydration of the cementitious material, thus improving the mechanical properties of BFR-GTCM. Full article

Recently, short basalt fibres (BFs) have been gaining considerable attention in the building materials industry because of their excellent mechanical properties and lower production cost than their counterparts. Reinforcing geopolymer composites with small volumes of fibres has been proven an efficient technique to enhance concrete’s mechanical properties and durability. However, to date, no study has investigated the effect of basalt fibers’ various lengths and volume content on self-compacted geopolymer concrete’s fresh and mechanical properties (SCGC). SCGC is prepared by mixing fly ash, slag, and micro fly ash as the binder with a solid alkali-activator compound named anhydrous sodium metasilicate (Na₂SiO₃). In the present study, a hybrid length of long and short basalt fibres with different weight contents were investigated to reap the benefits of multi-scale characteristics of a single fibre type. A total of 10 mixtures were developed incorporating a single length and a hybrid mix of long (30) mm and short (12) mm basalt fibres, with a weight of 1%, 1.5% and 2% of the total binder content, respectively. The fresh and mechanical properties of SCGC incorporating a hybrid mix of long and short basalt fibres were compared to plain SCGC and SCGC containing a single fibres length. The results indicate that the hybridization of long and short fibres in SCGC mixture yields better mechanical properties than single-length BF-reinforced SCGC. A hybrid fibre coefficient equation will be validated against the mechanical properties results obtained from the current experimental investigation on SCGC to assess its applicability for different concrete mixes. Full article

Basalt fibre is derived from volcanic rocks and has similar mechanical properties as glass fibre. However, poor fibre-matrix compatibility and processing issues are the main factors that have restricted the mechanical performance of basalt fibre-reinforced thermoplastic composites (BFRTP). In this work, basalt continuous fibre composites with polypropylene (PP) and polycarbonate (PC) matrices were studied. The composites were processed by compression moulding, and a processing study was conducted to achieve good quality composites. For the BF-PC composites, the optimisation of material preparation and processing steps allowed the polymer to impregnate the fibres with minimal fibre movements, hence improving impregnation and mechanical properties. For BF-PP composites, a compatibiliser was required to improve fibre-matrix compatibility. The compatibiliser significantly improved the tensile and impact strength values for short BF-PP composites and continued to increase at 40 wt%. Furthermore, the analytical modelling of the Young’s moduli indicated that the induced fibre orientation during processing for short BF-PP composites and unidirectional (UD) BF-PC composites had better stress transfer than that of UD BF-PP composites. Full article