Basalt Fiber Content Research Articles

Farklı oranlardaki bazalt fiber takviyesinin kaolinin serbest basınç dayanımına etkisi

There are many materials used to stabilize or reinforcement low strength soils. While additives such as fly ash, lime, tuff, silica fume are preferred in stabilization works, fibers are used in reinforcement works. The use of fiber, which has emerged as an alternative to traditional methods, has become widespread. The most preferred fiber types in soil reinforcement are glass, polypropylene and basalt fibers. Basalt fiber, which is produced from basalt rock and widely distributed in nature, was chosen as a reinforcement material in this study, which is increasingly used due to its high strength, economic, environmentally friendly, natural and many other superior properties. The aim of this study is to examine the effects of basalt fiber ratio on strength in low plasticity kaolin clay reinforced with basalt fiber. For this purpose, unconfined pressure tests were carried out on cylindrical samples prepared by adding 6 mm long basalt fiber at different rates to clay and compressing it at optimum water content. In the samples reinforced with basalt fiber, the maximum strength was obtained in the sample with 2% basalt fiber ratio. It was determined that the strength decreased in samples with higher basalt fiber content.

Study on Eccentric Compression Mechanical Characteristics of Basalt Fiber-Reinforced Recycled Aggregate Concrete-Filled Circular Steel Tubular Column

During this study, eight basalt fiber-reinforced recycled aggregate concrete-filled circular steel-tubular (C-BFRRACFST) column specimens were subjected to eccentric compression tests with different replacement ratios of recycled coarse aggregate (RCA), basalt fiber (BF) contents, length-diameter (L/D), and eccentricity. The whole process of stress as well as failure mode of the specimens were observed, and a load–displacement curve as well as a load–strain curve for the specimens were measured. The impacts of various parameters upon the bearing capacity, peak displacement, and ductility coefficient of the specimens were analyzed. Subsequently, a 3D finite element model of the C-BFRRACFST column was established, and the whole process of stress was simulated. Based on the finite element simulation results, the N/Nu-M/Mu correlation strength curve of the C-BFRRACFST columns was verified. The exploration demonstrated that under eccentric load, the C-BFRRACFST column eventually underwent destruction of the overall instability. The load–axial displacement curve was characterized as three stress stages: elastic, elastic–plastic, declining, as well as declining stages. The strain of the mid-span section for the specimens follows the plane section assumption, and the lateral deflection basically follows the sine waveform curve. The ultimate bearing capacity of the specimens exhibited little change as the replacement ratio of RCA improved, while the ductility progressively reduced. Furthermore, the ultimate bearing capacity of the specimens failed to be obviously changed as the BF content enhanced, while the ductility progressively rose. Increasing the L/D gradually reduced the specimen’s ultimate bearing capacity alongside its ductility. The corrected N/Nu-M/Mu curve agreed well with the findings of finite element simulation.

Influence of basalt fiber on pore structure, mechanical performance and damage evolution of cemented tailings backfill

To study the influence of the addition of basalt fibers on the mechanical properties, pore structure, and damage evolution characteristics of the cemented tailings backfill (CTB), the uniaxial compression tests, nuclear magnetic resonance tests and scanning electron microscopy analysis were conducted on the CTB with four different content and lengths of basalt fibers. Test results show the following. (1) An increase in the content of basalt fibers will lead to an increase in the proportion of micropores and secondary pores in the CTB, while a decrease in the proportion of macropores. The influence of basalt fiber length on pore structure is not as significant as the content. (2) With the increase of basalt fiber content and length, the peak stress and peak strain of the CTB increase, but the elastic modulus decreases. Basalt fiber can significantly improve the ductility and bearing time of the CTB, with a length of 12 mm and a content of 1.5 % having the best effect. The length of basalt fibers affects macroscopic mechanics more than content. (3) The CTB without fiber have fewer cracks and faster crack propagation speed, while the CTB with fiber have more cracks and slower crack propagation speed. Basalt fibers mainly play a bridging role between hydration products, delaying the failure process of the sample. (4) A damage constitutive model was constructed. The rationality and reliability of the model were verified, and the damage evolution law of CTB was analyzed. The content and length of basalt fibers have a positive impact on damage evolution.

Study on properties of basalt fiber reinforcing reactive powder concrete under different curing conditions

The influence of basalt fiber (BF) on the mechanical properties of reactive powder concrete (RPC) under different curing systems was studied. Three curing systems were adopted: natural curing (NC), standard curing (SC) and combined curing (CC). The design formulas for compressive and splitting tensile strength of basalt fiber reactive powder concrete (BFRPC) were established. The hydration process and strength changes of BFRPC under different systems were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The test results showed that the CC was better than the SC and slightly better than the NC, while the hydration of the CC was insufficient in the later stage, and the growth rate was significantly lower than the SC or NC. BF showed good compatibility with the matrix and was closely bonded. BF with proper content and the matrix were pressed together to improve the mechanical properties of BFRPC, while an excess of BF content would cause weakened areas and reduce strength. In comparison to plain RPC (with BF content of 0 %), the maximum increase rates of 28-day compressive strength of BFRPC under NC, SC and CC systems were 22.8 %, 18.4 % and 8.9 %, respectively. As for 28-day splitting tensile strength, the maximum increase rates became 74.5 %, 66.5 % and 49.67 %, respectively. Considering the economy and practicability of the actual project, the strength prediction formula of BFRPC was put forward to facilitate its popularization and application.

Study on the Modification Effect and Mechanism of a Compound Mineral Additive and Basalt Fiber on Coal Gangue Concrete

Compared with ordinary concrete, coal gangue concrete (CGC) is limited by its poor mechanical properties and frost resistance, which seriously restricts its wide application in cold regions. In order to improve the resource utilization rate of coal gangue, this paper takes advantage of the ‘overlapping effect’, ‘micro-aggregate filling effect’ and ‘volcanic ash effect’ of fly ash (FA) and silica fume (SF) and the anti-cracking effect of basalt fiber (BF) to study their effects on the macro performance of CGC and the micro modification mechanism. Modified CGC was prepared by replacing cement with 20% total mineral additives and adding BF. Taking different fly ash and silica fume incorporation ratios (F/S) and the BF content as variables, the research was carried out from two scales of macro performance and microstructure. The results show that the mechanical properties and frost resistance of CGC can be significantly improved by adding mineral additives and BF, and the modification effect is better with a decrease in F/S. When F/S = 1, the compressive strength, splitting tensile strength and flexural strength of the specimens increased by 13.73%, 8.37% and 4.27%, respectively. After 300 freeze–thaw cycles, the specimen was still not damaged by freezing and thawing. At the same time, keeping F/S = 3 unchanged and changing the BF content, it was found that the optimal content of BF was 0.15 vol% under the combined action of BF, FA and SF. In terms of microstructure, the addition of mineral additives and BF segregates and fills the macropores in the structure, greatly reducing the harmful pores and turning them into harmless and less harmful pores. When F/S = 1, the number of multi-harmful pores decreased by 16.89%, and the number of harmless pores and less harmful pores increased by 9.19%, which greatly optimized the pore structure and pore gradation.

Mechanical properties and microstructure of SWGA-BF improved rock muck discharged from slurry shield tunnels

The waste muck discharged during shield tunneling has become the main source of urban construction waste. The modification of discharged muck from shield tunnels into roadbed materials can significantly improve resource utilization efficiency, but freeze–thaw environments can pose safety hazards. In this study, solid waste gelling agents (SWGAs) (50 % cement, 36 % blast furnace slag, 6 % calcium aluminate, 5 % semihydrate gypsum, 2 % calcium oxide, and 1 % alum) and basalt fiber (BF) were used as reinforcing materials for the waste muck discharged from the construction of slurry shield tunnels in rock formations. By conducting freeze–thaw cycle tests, unconfined compression tests, scanning electron microscopy (SEM) analysis, and image analysis by the ImageJ software, the effect of the freeze–thaw environment on the mechanical properties and microstructure of the improved tunnel muck by SWGA-BF composite was studied. The results show that the damage to the unconfined compressive strength (UCS) of the SWGA-BF improved tunnel muck caused by freeze–thaw cycling can be divided into three stages: rapid damage stage, slow damage stage, and basically stable stage, corresponding to N = 0 ∼ 3, N = 3 ∼ 9 and N > 9, and the damage degree generated by freeze–thaw cycle in each stage is 33.9 %, 16.7 %, and 5.0 %, respectively. The first freeze–thaw cycle causes the greatest damage. The variation characteristics of the elastic modulus of improved tunnel muck were similar to those of UCS, and the value of elastic modulus is linearly related to the UCS. The optimal content of BF is 0.5 %. As the fiber content increases, the yield strain and failure strain increase in a wavy manner. SEM tests reveal that the freeze–thaw environment increases the pore area, the size, and the number of fissures of the improved tunnel muck. However, after 12 freeze–thaw cycles, the particle diameter and abundance decreased by 20.46 % and 4.89 %, indicating that the freeze–thaw cycle effect has a greater impact on particle diameter than particle abundance. The deterioration of the microstructure eventually decreased the macro tunnel muck strength. These results have important reference values for the reutilization of waste muck discharged from shield tunneling for roadbed backfill materials in seasonally frozen areas.

Early age dynamic mechanical properties of basalt fiber reinforced early strength concrete

AbstractThe dynamic compression test was carried out on basalt fiber reinforced early strength concrete (BFRESC) with ages of 4–24 h by the split Hopkinson pressure bar (SHPB) test system. The effects of curing age and basalt fiber content on dynamic mechanical properties of ESC was analyzed. The result shows that the dynamic compressive strength and specific energy absorption of BFRESC at early ages increase continuously with the increase of fiber content. The dynamic compressive strength of concrete at the early ages increases exponentially with the strain rate. With the increase of curing age, the strain rate sensitivity of dynamic compressive strength of concrete increases gradually, and the strain rate sensitivity of dynamic compressive strength of BFRESC with fiber content of 0.1% is the strongest. The specific energy absorption of concrete at early ages increases linearly with the strain rate. With the increase of curing age, the strain rate sensitivity of specific energy absorption of concrete increases gradually, and basalt fiber can enhance the strain rate sensitivity of specific energy absorption of concrete. Based on the comparison with the formula for dynamic increase factor (DIF) calculation provided by Comite Euro‐International du Beton (CEB), etc., a model of DIF based on the increase of curing age is proposed.

Investigation of the basalt fiber type and content on performances of cement mortar and concrete

Basalt fiber (BF), a naturally recyclable material, has attracted a lot of research in the field of civil engineering in recent years as the idea of sustainable development has gained traction. However, the surface of basalt fiber is smooth, and the bonding force with the cement matrix is insufficient, making popularizing and using basalt fiber-reinforced cement-based products challenging. In this study, a bundle spliced basalt fiber (BSBF) with strong bonding force, good dispersion, and two kinds of SCBF (SCBF-Ⅰ and SCBF-Ⅱ) with surface modifiers were selected. The properties of BF and BF-reinforced cement mortar were tested, and the optimum content of BSBF with a length of 12 mm (BSBF-12) was determined by concrete performance tests.The results showed: The tensile strength of BSBF decreases after alkali corrosion, but it can still maintain a high level. BSBF has a significant benefit over SCBF in terms of increasing the early strength and flexural toughness of cement mortar. BSBF-12 was selected for a late-stage concrete test investigation. The slump of the concrete progressively reduces as the BSBF-12 content increases, and the mechanical properties reveal a trend of first rising and then reducing. The optimal BSBF-12 content is 0.3 vol%, which increases compressive strength, split tensile strength, flexural strength, and bending toughness index of concrete by 10.39%, 61.16%, 13.33%, and 50.85%, correspondingly. Furthermore, various BSBF-12 contents improve the durability of the concrete to differing degrees.

Mechanical properties and microscopic characteristics of fly ash–slag composite backfill

The strength of the backfill is crucial for safe and efficient mining, and the cementing material is the key to obtaining a strong backfill. In this paper, industrial waste was used as a raw material, into which basis basalt fibres of different lengths and dosages were incorporated. First, the influencing factors were determined through orthogonal test designs. The optimal ratio of solid–liquid ratio of 2 and basalt fiber content of 2% and length of 6 mm was obtained, and thereby the complete proportion of the backfill material was obtained. The compressive strength and slump of the backfill material mixed with basalt fibres were investigated, and the interfacial mechanism of the backfill material was analysed at the microscopic level using scanning electron microscopy and X-ray diffraction. The results indicated that the degrees of influence of the different factors on the mechanical properties of the backfill material decreased in the following order: Solid–liquid ratio > fibre dosage > fibre length. Furthermore, there were different degrees of interaction among them. Under the best test proportion, that is, when the Solid–liquid ratio was 2, the fibre dosage was 2%, and the fibre length was 6 mm, the slump was 210 mm, and the compressive strength was 5.03 MPa. The mechanical properties were the best at this time. Through data regression, the relationship between the fibre dosage and the average peak stress was established, and the full curve expression for the uniaxial compressive stress–strain of the BFGF specimen was obtained. According to a microscopic characterisation analysis, the slag formed C–S–H gel, which contributed to the early-stage strength of the filling material; fly ash and coal gangue contained a large amount of aluminium, which formed hydrated aluminosilicate with a framework structure, and this contributed significantly to the later-stage strength of the backfill material. The addition of basalt fibres reduces the internal defects of the backfill, allowing the internal pore structure of the backfill to be optimised and the compressive strength to be increased. The results of this study have been successfully implemented in actual projects. Additionally, they provide a reference for similar mine management projects and have considerable promotion and application value.

Research on fire resistance and economy of basalt fiber insulation mortar

The construction sector has become the most critical source of carbon emissions, but the existing thermal insulation materials such as thermal insulation mortar have obvious limitations, so it is urgent to develop building thermal insulation materials with superior performance and low cost. Aiming at the problem of poor bond strength of foam thermal insulation mortar, this research team selected basalt fiber as admixture to verify the influence of basalt fiber content on its performance and the economic feasibility of thermal insulation mortar. The main finding is that basalt fiber as an additive can obviously improve the crack resistance of thermal insulation mortar. When the content of basalt fiber increases from 0 to 2.5%, the compressive strength of mortar increases at first and then decreases, and the bond strength increases nonlinearly, but the thermal conductivity and dry density also increase. Therefore, the optimal content of basalt fiber is 1.5%. The improvement effect of fire resistance of thermal insulation mortar with 1.5% basalt fiber content is better. After curing for 28 days, the mass loss rate of the sample is reduced by about 11.1% after high temperature, and the relative compressive strength is increased by about 9.71% after high temperature. The raw material cost of the new fireproof thermal insulation mortar improved by basalt fiber is lower, and the cost of the finished product is reduced by 16.98%, 28.18%, 33.05% and 38.96%, respectively, compared with the four types of thermal insulation mortar already used in the market. More importantly, the economic recovery period of the new fireproof and thermal insulation mortar is undoubtedly shorter than that of alternative thermal insulation or energy storage materials, which not only achieves low emission and environmental protection, but also satisfies the economic feasibility.

Rheological and mechanical characteristics of basalt fiber UHPC incorporating waste glass powder in lieu of cement

Ultra-High-Performance Concrete (UHPC) represents an exceptionally durable construction material distinguished by its notable strength, ductility, and durability. Previous investigations have demonstrated a limited exploration of UHPC containing basalt fiber and waste glass as a substitute for cement. Current study concentrates on assessing the impact of incorporating waste glass powder (WGP) in lieu of cement, on the workability, mechanical properties, and microstructural attributes of this composite. The substitution involved three distinct proportions of waste pozzolanic glass powder: 10%, 20%, and 30%, measured by weight. A substantial number of test specimens, exceeding one hundred, was accurately prepared to inspect the engineering characteristics of five varied UHPC formulations. Experimental outcomes underline that the optimum UHPC compressive strength was recorded at the 28-day when employing a 0.75% basalt fiber content and replacing 20% of cement with waste glass. This investigation establishes the distinctive contribution of WGP pozzolanic constituents in enhancing the microstructure of UHPC.

Advancing basalt fiber asphalt concrete design: A novel approach using gradient boosting and metaheuristic algorithms

Basalt Fiber Asphalt Concrete (BFAC) is an environmentally friendly and durable material with potential road, bridge, and infrastructure construction applications. This study investigates the application of Machine Learning (ML) models, specifically the classical Gradient Boosting (CGB) algorithm, in conjunction with metaheuristic algorithms, to predict the Marshall Stability (MS) and optimize the design of BFAC mixtures. The model is trained and tested on a comprehensive dataset of experimental samples, taking into account various input parameters, including basalt fiber (BF) properties, asphalt binder characteristics, and aggregate gradation. Hyperparameter tuning is employed to enhance the model's predictive performance using metaheuristic algorithms such as Particle Swarm Optimization (PSO), Hunger Games Search (HGS), and Bald Eagle Search (BES) and compared regarding the convergence and computational efficiency. The findings demonstrate that BES outperforms other algorithms, achieving the highest performance. The CGB-BES model is then applied to three optimization scenarios, focusing on maximizing the MS while minimizing BF and asphalt binder content. Post-processing and interpretation of the results reveal the importance of combining ML and materials engineering expertise. By highlighting the synergy between CGB-BES model and domain-specific knowledge, materials engineers can effectively optimize the mixtures and improve the design and performance of BFAC.

Mechanical performances and micro-level properties of basalt and PVA fiber reinforced engineered cementitious composite after high temperatures exposure

After high-temperature exposure, synthetic fibers with low melt temperature tend to exert negative influence on mechanical performance of engineered cementitious composite (ECC) and its elements. Basalt and PVA fiber reinforced hybrid-fiber ECC (basalt/PVA HF-ECC) is a promising way to address such drawback, due to the low cost, sustainability and high-temperature stability of basalt fiber. However, relevant researches only focus on fiber replacement and are still on primary stage, meanwhile their results show further performance improvements are required. In present study, basalt/PVA HF-ECC with superimposed basalt fiber content is proposed. Mechanical and micro-level related tests were conducted to investigate the effect of superimposed basalt fiber content after high-temperature exposure. Compressive test results showed basalt fiber could increase compressive strength at elevated temperatures. The optimal basalt fiber volume fraction was 0.8%, whereby compressive strength was higher than that of control PVA-ECC by 62.05%, 55.45% and 37.24% at 400 °C, 600 °C, and 800 °C. Tensile test results exhibited that stress-strain curves of basalt/PVA HF-ECC showed brittle behavior when PVA fiber melted at elevated temperatures, and first cracking strength also showed continuous increase as basalt fiber content increased. The optimal basalt fiber volume fraction was 1.2%, whereby first cracking strength was higher than that of control PVA-ECC by 48.43%, 42.38%, 36.30% and 50.41% at 23 °C, 400 °C, 600 °C, and 800 °C. Mercury intrusion porosimetry (MIP) tests showed basalt fiber reduced average pore diameter at elevated temperatures, while hardly exerted influence on porosity. At 600 °C and 800 °C, 0.8% and 1.2% content of basalt fiber decreased average pore diameter of control PVA-ECC by 13%–37%, and deduced peak heights of pore size distribution curves. SEM observation discussed and proved the basalt fiber contribution to strength improvement after high-temperature exposure. Rupture space related analysis was also used to discuss the tensile strain capacity deterioration at elevated temperatures. The present study investigates high-temperature mechanical performances and micro-level properties of basalt/PVA HF-ECC with superimposed basalt fiber content, thus promotes development of heat-resistant ECC with much reliable performances.

The Axial Compression Behavior of Basalt Fiber-Reinforced Recycled Aggregate Concrete-Filled Circular Steel-Tubular Column

Recycled aggregate concrete (RAC) technology has received a lot of attention as a green environmental protection technology. However, the unsatisfactory mechanical behavior of RAC restricts its application in engineering practice. The structure of basalt fiber-recycled aggregate concrete-filled circular steel tubes (C-BFRACFST) can dually improve the mechanical behavior of RAC. To observe the axial compression behavior of the C-BFRACFST column, seven specimens were designed with recycled aggregate replacement ratio (0%, 50%, 100%), basalt fiber (BF) content (0 kg/m3, 2 kg/m3, 4 kg/m3) and length–diameter (L/D, 5, 8, 11) as variable parameters for axial compression tests. The failure mode, load–displacement/strain curve, axial compression deformation, ultimate bearing capacity, energy dissipation, and ductility of specimens have been analyzed. The derived constitutive relation of core basalt fiber-reinforced recycled aggregate concrete (BFRAC) constrained by the circular steel tube and the 3D finite element model of C-BFRACFST column have been established to simulate the whole process of compression. It is observed that instability or shear failure occurs in specimens under axial compression load. When the recycled aggregate replacement ratio was increased from 50% to 100%, the change in the energy-dissipation capacity of the specimens was not significant but the ultimate bearing capacity and displacement ductility coefficient decreased by 3.45% and 8.91%, respectively. When the BF content was increased from 2 kg/m3 to 4kg/m3, the change in the ultimate bearing capacity of specimens was not significant; the energy-dissipation capacity at the later stage of bearing increased, and the displacement ductility coefficient was noted to increase by 13.34%. When the L/D was increased from 8 to 11, the energy-dissipation capacity of specimens was decreased, and the ultimate bearing capacity and displacement ductility coefficient declined by 1.37% and 43.52%, respectively. The finite element simulation results are in agreement with the test results.

Prediction of Restrained Shrinkage of New-to-old Concrete Interface

The focus of this study is on the shrinkage differences between new and old concrete, which can cause cracks at the bonding surface of the interface. The effects of various factors on shrinkage, such as the content of shrinkage reducing admixtures (SRA) the content of basalt fibers (BF) and the roughness at the new-to-old concrete interface (RI) are also examined. In this research, nine groups old-new concrete composite specimens were tested for shrinkage to gather experimental data. The restrained shrinkage mechanical model (RSMM) was deduced, and the restrained shrinkage model based on grey correlation analysis (RMGC) was proposed. The effectiveness and convenience of both prediction methods were evaluated by comparing their results to the experimental data. It was determined that the RMGC was more effective and convenient. Additionally, the research found that as the content of SRA and BF increases, shrinkage decreases. The effect of SRA was found to be more significant. As RI increases, shrinkage undergoes an initial increase and then decreases. The study can be used to inform the design and construction of structures that use both new and old concrete.

Neural Network Calculator of Rubber Characteristics with Improved Properties

A new technique for the use of Artificial Neural Networks (ANN) for the generalization and visual presentation of the results of experimental studies is proposed. The possibility of using ANN for cases for which their use was previously considered impossible is shown. ANN calculators have been created that summarize the results of experimental studies on the effect of trans-polynorbornene and basalt fiber on the characteristics of a rubber compound based on general-purpose rubbers (isoprene SKI-3, butadiene-methylstyrene SKMS-30ARK and butadiene SKD), which also contained vulcanizing agents (N, N′-dithiodimorpholine, thiuram D), vulcanization accelerators (sulfenamide C, 2-mercapto-benzothiazole), vulcanization activators (zinc white, stearic acid), emollients (industrial oil I-12A, rosin) and antioxidants (acetonanil H, diaphene FP). The rubber mixture was prepared on laboratory rollers LB 320 160/160. Subsequently, the rubber mixture was vulcanized in a P-V-100-3RT-2-PCD press. For the resulting vulcanizates, the physical and mechanical properties and their changes were determined after daily exposure to air and in a standard SZhR-1 hydrocarbon liquid at a temperature of 100 °C. We also studied the change in the mass of vulcanizates after exposure to industrial oil I-20A and water. The dynamic parameters (modulus of elasticity and mechanical loss tangent) of vulcanizates, which characterize their noise and vibration-absorbing properties, were studied on a Metravib VHF 104 dynamic mechanical analyzer. The created ANN calculators allow solving a direct problem - interpolating the dependences of all rubber characteristics on the content of basalt fiber, as well as solving inverse problems - to determine the required content of basalt fiber to create rubber with the required performance properties. The autonomous executable modules of the calculators developed by ANN were made and can be passed to everyone.

Enhancing Strength and Sustainability: Evaluating Glass and Basalt Fiber-Reinforced Biopolyamide as Alternatives for Petroleum-Based Polyamide Composite.

This study aims to analyze strength properties and low-cycle dynamic tests of composite materials modified with glass and basalt fibers. Biopolyamide 4.10 was used as the matrix, and the fiber contents were 15, 30, and 50% by weight. Static tensile tests, impact tests, and determination of mechanical hysteresis loops were carried out as strength tests. The length of the fibers in the produced composites and their processing properties were determined. The composite materials were compared with commercially available glass fiber-reinforced composites with 30 and 50% fiber contents. The results showed that such composites can successfully replace composite materials based on petroleum-based polymeric materials, providing high strength properties and reducing the negative environmental impact by using renewable sources. Composites with 30% basalt fiber composition were characterized by higher tensile strength by about 60% compared to commercially available composites with 30% glass fiber composition and an almost doubly increased Young's modulus. Increasing the content of basalt fibers to 50% results in a further increase in strength properties. Despite the lower tensile strength compared to polyamide 6 with 50% glass fiber content, basalt fibers provided an approximately 10% higher modulus of elasticity.

Rheological behavior of basalt fiber sprayed cementitious composites (BFSCC)

In the application of modern sprayed cementitious composites, more specific requirements have been proposed for crack resistance, toughness, and durability. By adding fibers with high strength and toughness to the cementitious matrix, the resulting composite material can exhibit excellent mechanical properties. Currently, the commonly used fiber materials of sprayed cementitious composites include steel fiber, polypropylene fiber, basalt fiber. As a type of green and sustainable building material, basalt fiber has been widely used in various engineering projects. In the field of sprayed cementitious composites (SCC), the addition of chopped basalt fibers can enhance its toughness and cracking resistance. However, fiber inclusion may also lead to reduced workability and equipment clogging. Therefore, the rheological behavior of basalt fiber sprayed cementitious composites (BFSCC) under mixing and spraying stages of construction become critical and essential to be fully investigated. In order to simulate the actual engineering application environment of BFSCC, a mortar spraying machine and ICAR rheometer were used to evaluate the variation of key rheological parameters under mixing and spraying stages of construction. The yield stress, plastic viscosity, and thixotropic indices of BFSCC under the influences of basalt fiber characteristics, i.e., type, content and hybrid length, were investigated. The time-dependent rheological behavior of BFSCC was also evaluated. The results indicated that there were significant differences on rheological behaviors under mixing and spraying stages of construction when the basalt fiber was introduced. The spraying process yielded a much higher static and dynamic yield stresses of BFSCC compared with those of mixing stage. Under the same fiber volume content, the plastic viscosity of BFSCC increased first and then decreased with an increase in fiber length in both stages, reaching a maximum at 12 mm. The time-dependent changes in the thixotropic index decreased first and then increased with an increase in time in both the mixing and spraying stages. A prediction model on rheological parameters for BFSCC under mixing and spraying stages was established in accordance with fiber characteristics.

Mechanical performance and carbonation resistance of basalt fiber—polypropylene fiber rubber concrete

The accumulation and incineration of waste tires have caused great damage to the environment. Therefore, recycling waste tires efficiently and economically has become an important issue in protecting world resources and the environment. In this study, 5%, 10%, and 15% rubber particles were used to replace fine sand in concrete, and basalt fibers (0.1%, 0.2%, and 0.3%) and polypropylene fibers (0.1%, 0.15%, and 0.2%) were added to rubber concrete to prepare hybrid fiber rubber concrete (HFRC). The experiments investigated the changes of mechanical properties of basalt (BF), polypropylene (PPF) fibers, and rubber particles when they were blended into concrete respectively, and the degree of influence of each factor on the mechanical and carbonation resistance of HFRC was investigated based on the orthogonal test. The results show that the rubber concrete’s mechanical and carbonation properties are improved to varying degrees after adding hybrid fibers. When the basalt fiber content is 0.2% and the polypropylene fiber content is 0.15%, the overall mechanical properties of HFRC reach the best state. When the basalt fiber content is 0.2%, the polypropylene fiber content is 0.15%, and the rubber content is 5%, the carbonation resistance of HFRC is the most ideal. In addition, the microstructure of HFRC was observed by scanning electron microscope.

Research on impact toughness and crack propagation of basalt fiber reinforced concrete under SHPB splitting test

To cope with accidents such as explosion and high-speed impact, it is necessary to study the dynamic mechanical response of basalt fiber reinforced concrete (BFRC) under impact load. The dynamic splitting test of BFRC was conducted under different impact air pressures by Φ50 mm split Hopkinson pressure bar (SHPB) experimental platform and dynamic DIC acquisition system. The dynamic mechanical characteristics of BFRC under impact load were studied, focusing on analyzing the effects of different basalt fiber (BF) volume rates and average strain rates on its impact toughness. Meanwhile, the process of crack initiation, propagation, and penetration in BFRC during damage and failure was analyzed by DIC technique, the propagation speed and width of tensile crack were calculated by strain nephogram and pixel information. The results show that BFRC with 0.3% fiber content has the highest dynamic splitting tensile strength, dissipated energy and ultimate toughness. The strain rate effect of post-peak toughness is more obvious than that of pre-peak toughness. BF increases the impact toughness of concrete mainly by affecting the post-peak toughness. The crack propagation speed of BFRC is the slowest and the tensile crack width is the smallest with 0.3% fiber content, that is, the appropriate BF content (0.3%) can effectively reduce the damage degree of the matrix under the impact load and has the most obvious effect on the crack resistance and toughening of the matrix.