Hypothesis: Polymer matrix composites (PMCs) have various structural applications. To improve the mechanical properties of PMCs, nanoparticles are usually added to polymer matrix as reinforcements to produce polymer matrix nanocomposites. This research investigates the effects of surface treatment of graphene nanoplatelets (GNPs) on the tensile and impact behavior of basalt fibers\ epoxy composites. Methods: For this purpose, surface treatment of GNPs was performed using (3-aminopropyl) trimethoxysilane. The presence of silicon and nitrogen elements, which are the main components of functionalization group on the surface of treated GNPs, was confirmed by EDX-SEM mapping analysis. The nanocomposites with different weight percentages of treated GNPs (0. 2, 0. 3, 0. 4 and 0. 5) were fabricated by hand lay-up method. Also, two composite samples, one without GNPs and the other with 0. 4 wt% untreated GNPs were fabricated to compare with those reinforced with treated GNPs. Tensile and Charpy impact tests were performed on fully cured samples. Findings: The results showed 21. 1, 3. 6, 35. 1 and 74. 6 percent increase in tensile strength, modulus of elasticity, fracture energy and impact strength, in the order given, for nanocomposites reinforced with 0. 4 wt% treated GNPs were obtained compared to those without GNPs. Also, 52. 1, 37. 5, 57. 9 and 25. 5 percent decrease in properties, in the stated order, were observed for nanocomposites with 0. 4 wt% of untreated GNPs compared to those without GNPs. According to the SEM images, the increase in tensile properties could be related to the improvement in the adhesion between basalt fibers and epoxy resin, and also the toughening mechanism of treated GNPs. The surface treatment increased the interaction between the GNPs and the matrix, and also the presence of treated GNPs promoted crack deflection phenomenon that is one of the major toughening mechanisms of GNPs. The reduction in the mechanical properties of sample containing 0. 4 wt% untreated GNPs was attributed to the uneven dispersion of GNPs in the epoxy matrix and the weak interactions between the graphene nanoplatelets and matrix and fiber.

Recently, geopolymer binders have been considered because of low cost, simple processes for synthesis and many raw materials in nature. Geopolymer with brittle nature does not have high strength and cannot be used alone for structural materials. Therefore, to use in different structures, the composite which is reinforced with fibers such as carbon, glass, basalt, etc hasbeen used. In this research, influence of different parameters such as firing temperature and weight fraction of continuous basalt fiber on strength of lithium-based geopolmer composites reinforced by basalt fibers was studied. Firstly, raw materials for geopolymer preparation were calcined. Then, geopolymer matrix with specific molar ratio was made with three different weight percent of basalt fiber. The Molds were put in an oven and after that the composites were taken out of the molds. Then the samples were cured at three different temperatures. After heat treatment, C-MOR of composites was tested and flexural strength and fracture energy for different samples were calculated. The results showed that basalt fiber composites at 200oC had high strength, but by increasing temperature the strength decreased. Also, Fracture energy of composites at 200oC was higher than other temperatures.

One of the mechanical methods of soil stabilization is the use of reinforcing elements such as geotextiles, geogrids and natural or artificial fibers. In recent years, the use of disconnected artificial or natural fibers has become commonplace with random distribution to improve the mechanical properties of soil. A new type of fiber that has a natural origin and its production and application has the least environmental impact is basalt fiber. The prominent advantages of this type of fiber are the high resistance in acidic, alkaline and saline environments, and mechanical properties that are competitive with other fibers. In this study, in addition to identification tests, a series of modified compression test, uniaxial compressive strength test and indirect tensile strength test and SEM electron microscopy was tested on clay stabilized with basalt fiber with random distribution. The focus of this research was mainly on the effect of fiber length and weight percentage on soil resistance parameters. For this purpose, basalt fibers were mixed with soil in weight percentages of 0. 25, 0. 5, 0. 75, 1, 1. 5, 2 and with three different lengths of 6, 12, 25 mm, then compressed with optimum moisture content. The results show that by increasing the weight percent and length of the fibers, compressive strength and tensile strength, initially increases and then decreases. But in general, the compressive strength and tensile strength of the reinforced soil is more than unreinforced and in all cases, reinforced samples are more ductile than unreinforced specimens.

In this study, the effects of different environmental temperatures and stacking sequences of fibers on the flexural properties of the hybrid composites including epoxy resin, basalt fibers, and thin-ply unidirectional (UD) carbon fibers were investigated. The hybrid composites were prepared by hand lay-up method with 2 layers of carbon thin-ply and 6 layers of basalt fibers. The samples were fabricated with three different stacking sequences of fibers in which the position of thin-ply UD carbon fibers changed from the center to the outermost layers. Also, the temperature effects on the flexural properties of samples were investigated by applying different temperatures of 25, 60, and 95 º, C. All samples were fractured gradually and showed pseudo-ductility phenomenon due to thin-ply UD carbon fibers. Results showed that by placing the thin-ply UD carbon fibers at the outermost layers, the flexural strength and modulus of samples increased significantly. For example, at the temperature of 25 º, C, the flexural modulus of the samples was about 42% higher than that of the sample with thin-ply UD carbon fibers at the center of samples. However, the strain values of samples increased by nearing the thin-ply UD carbon fibers to the center layers. Also, results indicated that increasing the temperature caused the reduction of flexural strength and modulus of samples while the strain values increased.

The effects of functionalized graphene nanoplatelets (FGN) on the flexural properties of basalt fibers/epoxy composites were studied. The functionalization of graphene was performed by 3-Aminopropyltrimethoxysilane. Four nanocomposites with different weight percentages of FGN (0. 2, 0. 3, 0. 4 and 0. 5) were fabricated via hand lay-up method. Among these four, the nanocomposite reinforced by 0. 4 wt. % FGN showed the best flexural behavior. To investigate the effects of graphene as well as its functionalization, two other composites one without graphene and another reinforced by 0. 4 wt. % of unfunctionalized graphene nanoplatelets (UFGN) were also fabricated. In comparison to the sample without graphene, the nanocomposite with 0. 4 wt. % of FGN showed respectively 89. 6, 252. 6 and 44. 6 percent improvements in the flexural strength, flexural modulus and fracture energy, but the nanocomposite with 0. 4 wt. % UFGN showed respectively 26. 2 and 10. 8 percent decrease in the flexural strength and fracture energy, although had a slight increase of 3. 1 percent in the flexural modulus. These results indicated that functionalization facilitated the dispersion of graphene in the matrix and thus enhanced its interaction to both matrix and basalt fibers. According to the Fourier transform infrared spectroscopy results, the improvement in the flexural properties is related to the functional groups whose presence on the graphene platelets enhanced better adherence to the polymer’ s molecules and the basalt fibers. Furthermore, scanning electron microscopy observations of the fracture surfaces showed better polymer to fiber interfacial adhesion and thus caused toughening mechanisms such as crack deflection, graphene delamination and crack pining in the FGN containing samples.

Fabricating Metal matrix composites (MMCs) reinforced by fibers is one of the biggest issues in the engineering in various industries, due to having production limitations. In this research has been tried to fabricate aluminum matrix composites reinforced by fibers through thixomixing as novel method in semi-solid state and by helping shear force. For doing this, the basalt fibers (with the volume fraction of 2, 4, and 6) were dispersed into the molten A356 aluminum and by creating the shear mixing in the range of semi-solid temperature of aluminum, the composites were fabricated. For investigating the mechanical behavior of fabricated composites, the Brinell hardness and shear punch tests were used. Also, microstructural investigations and elemental analysis by scanning electron microscope were performed. The obtained results showed that by increasing the fibers content, the hardness and shear strength were simultaneously improved, which resulted to improve the ultimate strength of composite. The shear strength from 119. 1 MPa (for without fibers sample) to 132. 3 MPa (in reinforced composite by 6 vol. % basalt fibers) was increased. Also, the hardness test results showed an increase in Brinell hardness from 62. 3 to 70. 8 Hb in the sample with 6 vol. % of basalt fibers. The ultimate tensile strength in this sample also showed the 10. 9% improvement. Microstructural investigations depicted that the formation of intermetallic compounds at the interface caused to improve the mechanical properties.

Recently, flexible and environmental-friendly aerogel blankets have attracted considerable attention. In this work, the novel silica aerogel/basalt blanket was prepared using basalt fibers via a two-step sol-gel process followed by an ambient drying method and immersing the basalt fiber layer into silica sol. The silica aerogel particles were characterized by FTIR, FE-SEM and nitrogen adsorption analysis. The morphology, hydrophobic properties and surface roughness of neat basalt fiber and its aerogel blanket were also investigated. The density if 0. 34 g/cm3, the porosity of 85%, mean pore size of 7± 1. 5 nm and the surface area of 750 m2/g for the nanostructured silica aerogel particles are obtained. The formation of nanostructured silica aerogel particles on the surface of basalt fibers in the sol-gel process were efficiently occurred leading to a strong hydrophobicity the blanket samples (contact angle of 114° ) compared to the hydrophilic neat basalt fibers. The surface roughness of basalt fiber in the blanket samples was increased due to the fiber surface coating with silica aerogel particles. Increasing the sol volume in the synthesis process increased the basalt surface roughness from 3. 6μ to 11μ .

In this study, the strain rate effect on the bending properties of fiber reinforced composites for three types of polymer composites namely phenolic resin reinforced by woven basalt fibers, woven carbon fibers, and woven basalt/ woven carbon fibers at a total volume fraction of approximately 35% has been determined. Flexural tests have been conducted at low range of strain rates included 0.03 min-1, 0.06 min-1 and 0.09 min-1. Specimens with identical geometry have been used in all the tests. Experimental results showed that the strain rate has a significant effect on the material response in bending. Results showed that, both the flexural modulus and the ultimate flexural strength of the three types of composites are increased with the increasing in the strain rate. Also, the bending properties of composites reinforced with woven carbon fibers are very sensitive to the strain rate during the test.

In order to reduce the weight of structures, reduce dead load and improve seismic performance, lightweight concrete can be used. Due to the use of lightweight materials that have a brittle and porous structure, the mechanical properties and durability of lightweight concrete are weaker than ordinary concrete. To improve the weaknesses of lightweight concrete, optimal amounts of fibers can be used in lightweight concrete mix design. In this article, the effect of using different amounts of polymer fibers and basalt, single and combined, on the mechanical properties and durability was investigated. A number of 124 cylindrical samples with a size of 300 x 150 mm were made for compressive strength and tensile strength tests. Also, 248 cylindrical samples with a size of 200 x 100 mm were made for tests. Experiments were performed on different samples for the ages of 28 and 90 days. The results showed that the addition of 1% polymer fibers increased the compressive strength by 24.4% and 26.92%, and the tensile strength by 66.12% and 72.22%, as well as the addition of 1.75% basalt fibers. increases by 18.13% and 14.93% and tensile strength by 41.93% and 47.22% at the ages of 28 and 90 days compared to the sample without fibers. Also, the addition of 1.25% basalt fibers had the best performance in improving the durability of lightweight concrete, so the amount of final water absorption of lightweight concrete decreased to 31.93% and 45.38%. Adding the optimal amount of fibers increased the electrical resistance to 46.54% -46.42%, and also caused the penetration of chloride ions into lightweight concrete at the ages of 28 and 90 days by 39.67% and 43.15% respectively. be reduced to a fiber-free sample. it was concluded that polymer fibers have the greatest effect in improving the mechanical properties of lightweight concrete.