Basalt Fiber Content Research Articles

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.

Enhanced mechanical properties, thermal behavior and foaming ability of PP‐g‐MAH modified PP/BF composites

AbstractThe mechanical properties of fiber‐reinforced polymer composites strongly depend on its interfacial bond strength and fiber content, and their further lightweight is the current urgent demands for industry. Basalt fiber (BF), as an emerging natural and environmental‐friendly material, possess a broad application prospect as it can replace glass fiber. Herein, strong PP/BF composites with excellent heat deflection temperature and enhanced impact performance were successfully prepared, which augmented with the increase of BF content. The effect of PP grafted with maleic anhydride (PP‐g‐MAH) on the interfacial bonding properties between BF and PP was investigated based on the PP/20BF composite system, which was significantly improved due to the reaction of maleic anhydride polar groups with the hydroxyl groups on the BF surface. The incorporation of PP‐g‐MAH led to 24.7%, 46.9%, and 77.2% increase in tensile strength, flexural strength and impact strength of PP/20BF composites, respectively. Moreover, the crystallization properties, rheological behavior and thermal stability of the composites were significantly enhanced, which all contributed to the refinement and densification of cellular structure. The cell size was reduced from 36.38 to 13.41 μm after the addition of PP‐g‐MAH with an opening distance of 2 mm, and the cell density was enhanced by nearly one order of magnitude to 6.43 × 107 cells/cm3. The cellular structure further lightens the weight of product and promotes the lightweight development of PP/BF composites.

Research on the Model for the Friction Coefficient of Resin-Based Friction Material and Its Experimental Verification

Resin-based friction materials have been widely used in the friction braking of automobiles and power machinery. Based on experiments for the variation law of friction and wear morphology, a new model for the friction coefficient of resin-based friction materials was proposed, which includes the effects of both the micro convex body on the surface of the friction material and the frictional film generated during the friction process. This quantitative model of friction coefficient materials was established for the modelling of shear strength, compressive strength, shear strength of the frictional film, contact load and wear morphology. The shear strength, compressive strength and wear morphology of the friction material were adjusted by changing the content of basalt fibers and flaky potassium magnesium titanate. Finally, the accuracy of this quantitative model of friction coefficient was verified through experiments on friction samples with different formulations and by changing the frictional contact load. The results show that the predicted friction coefficient of the model is in good agreement with the experimental friction coefficient, the difference between the upper and lower limits of the forecast is only 5.03% and 2.30%, respectively. Meanwhile, the influence of the ratio of shear strength to compressive strength on the friction coefficient is greater than the proportion of wear morphology. The proposed friction model provides a reference value for the study of new resin-based friction materials.

The durability of basalt-fiber-reinforced cement mortar under exposure to unilateral salt freezing cycles

Basalt fiber and cement-based materials have been widely applied in engineering structures. In this context, the durability of basalt-fiber-reinforced ordinary silicate mortar was systematically studied under exposure to unilateral salt freezing. The mechanical durability, chloride ion diffusion characteristics, and microscopic pore characteristics of cement mortar with basalt fiber content levels in the range of 0 kg/m3–1.5 kg/m3 were tested under exposure to 0–40 freeze–thaw cycles. The relationships of changes in the internal pore structure with mass loss, mechanical damage, and the physical properties of the material were also analyzed under exposure to salt freezing cycles. The results demonstrated that even a small amount of basalt fiber could significantly improve the mechanical properties of cement mortar under unilateral salt freezing and its resistance to salt freezing erosion. In particular, cement mortar with 1.2 kg/m3 basalt fiber content exhibited good durability of compressive and flexural strength, while the specimens with no basalt fibers exhibited a relatively large degree of internal porosity under exposure to unilateral salt freezing. Our work provides concrete evidence for changes in the porosity of mortar under exposure to unilateral salt freezing, with these changes showing an exponential relationship with mortar mass loss and a strong linear correlation with changes in the compressive strength, flexural strength, and chloride ion diffusion coefficient of the material.

Mechanical behaviour and acoustic emission characteristics of basalt fibre mortar rubble under uniaxial cyclic compression

To investigate the effect of basalt fibre (BF) content on the mechanical behaviour and damage characteristics of mortar rubble under cyclic loading, uniaxial compression tests and cyclic loading and unloading tests were carried out on specimens fabricated with different BF volume fractions. Based on damage mechanics theory, a damage ontology model of BF mortar rubble was developed. The damage of BF mortar rubble under cyclic loading was identified and analysed using acoustic emission (AE) techniques, and parameters such as the Felicity ratio (FR), ratio of the RA (rise time/amplitude) and the average frequency (RA/AF), response ratio, b-value and peak frequency were used to characterise the failure mechanism of BF mortar rubble. The results of this study revealed that the incorporation of BF increased the compressive strength by 9.3%-14.2%. The response ratios of the initial cycles were 91.2, 53.4 and 24.4 when the BF content was 0.2%, 0.3% and 0.4% respectively. The incorporation of BF helps to delay the onset of critical damage values. The peak frequency signals are concentrated in the region of 50 kHz and 160 kHz. the 50 kHz frequency represents the appearance of fractures in the matrix and the 160 kHz frequency signal represents the occurrence of brittle fractures in the aggregate. The FR trend was a good predictor of damage to the mortar rubble. The damage mode of the mortar rubble changed from tensile fracturing to composite fracturing due to the addition of BF. The performance optimisation concept of mortar rubble proposed in this study provides a reference for the optimal design of BF mortar rubble and thus has a strong application value.

Mechanical Properties of Basalt Fiber Reinforced Perlite Aggregate Cement Mortars

– In this study, the mechanical properties of basalt fiber reinforced perlite aggregate cementmortars were investigated. The aim of the research was to determine the effect of basalt fiber on the strengthproperties of cement mortar and to identify the optimal fiber content. Specimens with different proportionsof basalt fiber were prepared, and their compressive and flexural strengths were measured at 7 days and 28days. A control specimen with no fiber reinforcement (B0) was used for comparison.The results showed that basalt fiber generally enhanced the strength of the cement mortar. The specimenswith basalt fiber reinforcement exhibited higher compressive and flexural strengths compared to the controlspecimen (B0). Particularly, a more significant increase in strength values was observed in the specimenswith basalt fiber at the 28-day testing period. However, the effect of basalt fiber content and distributionvaried among the specimens. In some specimens (B1.5, B2, B3), a slight decrease in strength was observedat certain testing periods.This study highlights the significance of basalt fiber reinforced perlite aggregate cement mortars as aresearch area, considering the increasing demand for their use in construction applications.

Basalt-Fiber-Reinforced Phosphorus Building Gypsum Composite Materials (BRPGCs): An Analysis on Their Working Performance and Mechanical Properties

The preparation of fiber-reinforced phosphorus building gypsum composite materials (FRPGCs) is an important approach to enlarge the utilization of phosphogypsum resources. Through reinforcing phosphorus building gypsum (PBG) with basalt fiber (BF), this article probes into the effects of the length and fiber content of BF on the working performance and mechanical properties of basalt-fiber-reinforced phosphorus building gypsum composite materials (BRPGCs) and accesses the toughness of BRPGCs under bending loads using residual strength. The results showed that the addition of BF could significantly promote the mechanical properties of BRPGCs. However, due to the adverse effect of fibers on the working performance of BRPGCs, the fiber content was constrained. After adding 1.2% of 6 mm BF, the bending strength and compressive strength of FRPGCs reached maximum values of 10.98 MPa and 29.83 MPa, respectively. Under a bending load, BRPGCs exhibited an apparent ductile behavior. The P-δ curve presented five stages, with an evident phase of strength stability after cracking. A larger fiber content was conducive to the toughness of BRPGCs. When 1.6% of 6 mm BF was added, the residual strength of FRPGCs could reach 6.77 MPa.

Experimental study on uniaxial compressive properties and damage evolution of basalt fiber reinforced concrete after being subjected to high temperature

The study investigated basalt fiber reinforced concrete (BFRC) for failure characteristics after being subjected to high temperatures under uniaxial compression. Twenty-five sets of cylindrical BFRC specimens were carried out under different basalt fiber (BF) content and temperature. Based on 3D digital image correlation (3D-DIC) and acoustic emission (AE), the effects of temperature and volume content of BF on the compressive mechanical properties, damage evolution and failure mode of BFRC are analyzed. The results indicate that the proper volume content (0.26%) of BF can improve the compressive strength of concrete. Generally, the uniaxial compressive strength of BFRC decreases with increasing temperature. The internal and external damage evolution trend of BFRC is basically the same, which can be divided into pore compaction stage, stable crack growth stage and unstable crack growth stage. The proper volume content (0.26%) of BF reduces the degree of BFRC damage. The increase in the volume content of BF leads to an increase shear cracks proportion in BFRC, and the failure mode of the main crack gradually changes from tension-shear failure to shear failure. Conversely, the increase in temperature increased the degree of BFRC damage. The internal and external failure modes of BFRC are basically the same. At 20 °C, the failure of concrete without basalt fiber is mainly tensile crack. With the increase of temperature, the main failure mode is tension-shear failure.

Effects of hybrid fibers on properties of desulfurized gypsum-based composite cementitious materials

Basalt fiber (BF) and polyvinyl alcohol fiber (PVAF) were mixed into desulfurized gypsum-based composite cementitious material (DGCCM) by an orthogonal test to prepare hybrid fiber-reinforced DGCCM, whose mechanical properties, water resistance, and durability were studied using visual, range, variance, and microstructure analyses. The results show that combining the two fibers improved the mechanical properties, water resistance, and durability of DGCCM. In terms of mechanical properties, the maximum absolute dry flexural strength and compressive strength increased by 70.05% and 64.52%, respectively, compared with the blank group. PVAF played a better role than BF in crack resistance and toughening, hence contributing more. When the content of PVFA and BF increased to 0.5% and 0.75%, respectively, the water resistance of hybrid fiber-reinforced DGCCM was better. The enhancement showed that BF had a more significant effect on the softening coefficient of DGCCM than PVAF. The incorporation of fibers inhibits the generation of a large number of cracks during the dry-wet and freeze–thaw cycles of DGCCM, which greatly improves its durability. When the content of PVAF and BF were both increased to 0.5%, the durability of hybrid fiber-reinforced DGCCM was better.

Effect of Basalt Fiber Content and Length on the Strength and Crack Development of Polyvinyl Alcohol/Basalt Hybrid Fiber-Reinforced Cement Soil.

Polyvinyl alcohol (PVA) fiber is widely used in geotechnical engineering because of its excellent physical and mechanical properties; however, PVA fibers are prone to aging, while basalt fiber has a natural anti-aging ability, which can be added to cement material to effectively eliminate the effects of aging on PVA fiber. Previous experiments identified that the optimum content of PVA fiber is 0.5% (mass fraction, the same below). Based on this, we continued to add basalt fibers of different lengths (3 mm, 6 mm, 9 mm, 12 mm, 18 mm, 30 mm) and different contents (0%, 0.25%, 0.5%, 0.75%, 1%) to study the effect of both length and content of basalt fibers on the strength of cement soil specimens. It was concluded that adding 0.5 % of 9 mm basalt fiber results in the greatest increase in unconfined compressive strength (UCS). The UCS reached 12.59 MPa, which was 71% higher than specimens without fiber, and a regression analysis was carried out to obtain the relationship among them. The ratio of cement soil in the highest UCS and the relationship among the UCS, the length, and the content of basalt fiber can be used as a reference for practical projects. In addition, digital image correlation (DIC) technology was used to analyze the surface cracks and horizontal strain field when the peak strain was reached at each content and length of the basalt fiber. Finally, the curing mechanism for hybrid fiber cement soil was analyzed by combining the results of the UCS test, DIC test, and SEM test.

Rheological and Mechanical Properties of Bentonite-Cement Paste Reinforced with Basalt Fibers.

Bentonite cement paste (BCP) is among the grouting materials used widely in large-pore grouting and karst cave treatment. The mechanical properties of bentonite cement paste (BCP) will be improved by additional basalt fibers (BF). In this study, the effects of basalt fiber (BF) contents and their lengths on the rheological and mechanical properties of bentonite cement paste (BCP) have been examined. Yield stress (YS), plastic viscosity (PV), unconfined compressive strength (UCS), and splitting tensile strength (STS) were used to evaluate the rheological and mechanical properties of basalt fiber-reinforced bentonite cement paste (BFBCP). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) characterize microstructure development. The results indicate that the Bingham model can provide the rheological behavior of basalt fibers and bentonite cement paste (BFBCP). The yield stress (YS) and plastic viscosity (PV) increase as the content and length of basalt fiber (BF) increase. The effect of fiber content on yield stress (YS) and plastic viscosity (PV) is greater than that of fiber length. The addition of basalt fiber (BF) enhanced the unconfined compressive strength (UCS) and splitting tensile strength (STS) of basalt fiber-reinforced bentonite cement paste (BFBCP) at the optimum basalt fiber (BF) content of 0.6%. The optimum basalt fiber (BF) content tends to increase as curing age increases. The basalt fiber length of 9 mm is the most effective for improving unconfined compressive strength (UCS) and splitting tensile strength (STS). The large increments in unconfined compressive strength (UCS) and splitting tensile strength (STS) were 19.17% and 28.21% for the basalt fiber-reinforced bentonite cement paste (BFBCP), with a basalt fiber length of 9 mm and content of 0.6%. Scanning electron microscopy (SEM) shows that the randomly distributed basalt fiber (BF) forms a spatial network structure in basalt fiber-reinforced bentonite cement paste (BFBCP), which composes a stress system under the action of cementation. Basalt fibers (BF) used in crack generation processes slow down the flow through bridging and occur in the substrate to improve the mechanical properties of basalt fiber-reinforced bentonite cement paste (BFBCP).

Synergistic effect of aramid and basalt fibers on mechanical, thermal and dynamic properties of polylactide hybrid composites

Today's market is looking for materials that have high-strength properties and are biobased at the same time. This manuscript demonstrates the possibility of reinforcing polylactide (PLA) through the incorporation of two types of fibers to produce high-performance composites. PLA composites reinforced with aramid (AF) and basalt fibers (BF) were produced by injection molding (10 wt%, 15 wt% and 20 wt%). Manufactured materials have undergone extensive analysis including mechanical, thermal, thermodynamic and structural studies. The increase of the fiber content resulted in significantly improved mechanical properties of the materials. Composites with 20 wt% of the fibers exhibited an increase in Young's modulus of ∼160%, and improved tensile strength by 30% compared to neat PLA. Moreover, the results indicated that each type of fiber was responsible for enhancing specific mechanical properties. AF improved Young's modulus such that for composites containing only 10 wt% of this fiber, Young's modulus increased by ∼100%, while the same content of BF alone increased Young's modulus by 43%. In the case of tensile strength, composites with BF exhibited higher values than seen for AF with improvement of 19% compared to the case of AF where only 3% improvement was seen compared to PLA. Statistical analysis revealed that the additives had a significant impact on the change of both physical and mechanical properties.The thermomechanical tests followed a similar trend as the mechanical ones, such that a higher content of the filler caused an increase in the storage modulus. The simultaneous addition of AF and BF resulted in the same increase in the stiffness of the composites as the addition of the same weight value of expensive aramid fibers. The addition of fibers has not however changed the characteristic temperatures obtained during differential scanning calorimetry.The work presents the possibility of creating hybrid materials with tailorable mechanical and structural properties. We demonstrate that with different fibers it is possible to tune properties of polymeric composites and make them suitable for specific applications.

Mechanical properties of a novel UHPC reinforced with macro basalt fibers

Adding fibers in ultra-high performance concrete (UHPC) significantly enhances its mechanical properties. This study investigated the effects of the novel macro basalt fibers (MBF) content and geometric characteristics on flowability and mechanical properties of UHPC, the MBF which was a kind of minibar composited of basalt fiber reinforced polymers (BFRP). Two fiber shapes, including straight and twisted shape, and two aspect ratios with the volume fractions ranging from 0% to 3% were employed. The fiber distribution, interfacial bonding behavior between MBF and UHPC were tested and evaluated. The effects of MBF on the flowability, compressive strength, flexural strength and toughness of UHPC were revealed. The toughness, compressive strength, and flexural strength of UHPC increased with the increase of MBF content, but the flowability decreased. The relatively uniform fiber distribution was observed when the MBF content was lower than 3%. Compared with the straight MBF, the twisted MBF showed higher bonding behavior between fiber and UHPC. It resulted in that the twisted MBF performed more efficient in enhancing mechanical properties of UHPC than the straight MBF. The flexural post-cracking strength of UHPC with various MBF contents and geometric characteristics could be accurately predicted using the quadratic model and the modified model based on the Composited Theory because the values of R2 were more than 0.95.

Mechanical Properties under Compression and Microscopy Analysis of Basalt Fiber Reinforced Recycled Aggregate Concrete

In this study, the basalt fiber content (0%, 0.075%, and 0.15%) and replacement ratio of recycled coarse aggregate (0%, 50%, and 100%) were used as parameters, and the compressive strength of 15 cubes and 15 prisms was analyzed. The failure morphology of the specimens was characterized, and the cubic compressive strength, axial compressive strength, elastic modulus, Poisson's ratio, and other mechanical property indices of the specimens were measured. Upon increasing the replacement ratio, the degree of damage of the specimens gradually increased, whereas the cubic compressive strength, axial compressive strength, and elastic modulus gradually decreased. As the replacement ratio was increased from 50% to 100%, the cubic compressive strength and elastic modulus were noted to decrease the most by about 9.07% and 9.87%, respectively. On the other hand, the Poisson's ratio first decreased, followed by an increase. Upon increasing the fiber content, the degree of damage of the specimens was gradually reduced, whereas the cubic compressive strength, axial compressive strength, and elastic modulus gradually increased. As the fiber content increased from 0.075% to 0.15%, the axial compressive strength and elastic modulus increased the most by about 6.65% and 10.19%, respectively. On the other hand, the Poisson's ratio gradually decreased. Based on the test data, the functional relationships between the strength indices and different variables, as well as the conversion value of each strength index and different variables were established; after comparison and verification, the formula calculation results were found to be in good agreement with the test results. The microstructural changes in the basalt fiber reinforced recycled aggregate concrete were characterized by scanning electron microscopy (SEM), and the changes in the mechanical properties of the basalt fiber reinforced recycled aggregate concrete as well as the mechanism of fiber modification and reinforcement were explained from a micro perspective.

Study of the Compressive Properties of Heavy Calcium Carbonate-Reinforced Epoxy Composite Spheres (HC-R-EMS) Composite Lightweight Concrete.

Lightweight concrete is one of the effective means to solve the problems of structural component weight, energy efficiency, and fire safety in modern civil engineering. Heavy calcium carbonate-reinforced epoxy composite spheres (HC-R-EMS) were prepared by the ball milling method, and HC-R-EMS, cement, and hollow glass microspheres (HGMS) were mixed into the mold by the molding method to prepare composite lightweight concrete. The relationship between the HC-R-EMS volumetric fraction, the initial inner diameter of the HC-R-EMS, the number of layers of HC-R-EMS, the HGMS volume ratio, the basalt fiber length and content, and the multi-phase composite lightweight concrete density and compressive strength was studied. The experimental results show that the density of the lightweight concrete ranges between 0.953-1.679 g/cm3 and the compressive strength ranges between 1.59-17.26 MPa, where the volume fraction of HC-R-EMS is 90%, the initial internal diameter is 8-9 mm, and the number of layers of HC-R-EMS is three. The lightweight concrete can meet the requirements of high strength (12.67 MPa) and low density (0.953 g/cm3). In addition, the addition of basalt fiber (BF) can effectively improve the compressive strength of the material without changing the density of the material. From a micro-level perspective, HC-R-EMS is closely combined with the cement matrix, which is conducive to increasing the compressive strength of concrete. Basalt fibers connect the matrix into a network, improving the maximum limit force of the concrete.

Influence of Different Lengths and Volumes of Basalt Fibre on Mechanical Properties of Concrete

In this research work, the influence of basalt fiber lengths and volumes on mechanical properties of concrete such as compressive strength, flexure strength and split tensile strength are studied. 12 and 24 mm lengths of basalt fiber having the same diameter (13 µm) were used in the experimental work. The influence of 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.4% and 0.5% volume of basalt fiber on mechanical properties of concrete have been studied. The results of conventional concrete and basalt fiber reinforced concrete were compared. Normal strength concrete M30 grade was considered in the work and the mechanical properties were measured at 3, 7 and 28 days of hydration period. The experimental investigation shows that high dosage of fibers creates workability problems such as mixing, clumping and balling effects. Experimental results show that there is no improvement in the compressive strength of concrete when basalt fibers were added in plain concrete mix at all ages of concrete. Moreover, the compressive strength values become unstable when basalt fibers are added to concrete. Maximum value of split tensile strength and flexure strength was obtained for 0.35% (9.275 kg/m³) basalt fiber content for both 12mm and 24mm length of basalt fiber at all ages of concrete. Comparing both 12mm and 24mm basalt fiber lengths, the 24 mm length of fiber has shown superior performance in relation to flexure strength and split tensile strength. Overall, the optimum length of basalt fiber is 24 mm and the optimum volume fraction of basalt fiber is 0.35%.