جستجوی مقالات مرتبط با کلیدواژه « glass fibers » در نشریات گروه « عمران »

Concrete is the most used construction material in the world. Today, there are various concretes with different applications in the industry. One of the types of concrete is fiber concrete. In this study, several concrete samples were made with steel, glass and polypropylene fibers and the effect of the volume and weight percentages of each of the fibers in improving the compressive strength of the samples at temperatures Different has been checked. In order to check the results and the possibility of comparing it with the behavior of normal concrete, a type of concrete without fibers was also made using common materials and similar tests were performed on it. Based on the investigations, the results showed that the concrete samples with steel fibers tolerated higher temperature levels and had higher resistance compared to other samples. In the samples, by adding 0.25% and 0.5% by volume of steel fibers to concrete, respectively, the compressive strength of the sample at high temperatures was improved. The strength of concrete samples with 3400 Kg/m was slightly decreased by increasing the percentage of fibers from 0.5% to 0.75%. The compressive strength of concrete containing steel fibers is 20% higher than that of concrete containing propylene fibers.

Today, the production of high-quality construction materials with low production costs is one of the needs of the construction industry. By using geopolymerization technology, it is possible to produce construction materials such as mortar, concrete, and geopolymer bricks with high mechanical strength and desirable quality. One of the aluminosilicate minerals that can be used to produce geopolymeric adhesive material is laterite. To improve the mechanical strength, durability, and physical characteristics of the geopolymer product, its reinforcement using different fibers such as glass fibers has been considered by various researchers. In the current research, using laboratory tests, the effect of reinforcing geopolymer mortar based on laterite powder using glass fibers was studied. The alkaline solution containing 6, 10, and 14 M sodium hydroxide was used to make samples of geopolymer mortar with laterite powder, without and containing glass fibers after 5 minutes of complete mixing, The samples were poured into 50 × 50 × 50 mm wooden molds and 40 × 40 × 160 mm prism molds and vibrated on a vibrating machine. After processing for 3 days in the greenhouse, the compressive and bending strength of the geopolymer samples as well as the water absorption percentage of the samples were measured. The results showed that the concentration of activating solution and glass fibers has a significant effect on the compressive and bending strength of geopolymer samples based on laterite powder with glass fibers. According to the obtained results, the increase in 3, 7, and 28 days compressive strength of geopolymer samples containing fibers varies between 10.9 and 47% compared to geopolymer samples without fibers. According to the results of this research, it is recommended to make geopolymer building materials based on laterite powder containing glass fibers with relatively high strength.

The addition of glass fibers has been used to stabilize the unsuitable clay of Rey city to reduce the subsidence in the strip foundations due to the improvement of resistance parameters. The combination of glass fibers with clay and the effect of using this additive on the stabilization of clay fine-grained clay (CL) were investigated in the laboratory. Soil samples in the natural state as well as in the combined state with different percentages of glass fibers equal to 0.2, 0.4 and 0.6, 0.8 and 1% of the dry weight of the soil were used for laboratory tests including standard compaction test, California load ratio test and direct cutting. Were located. The results show a decrease in unit weight of maximum soil volume and an increase in optimum moisture content, as well as a California load-bearing ratio by adding this material to the clay. The amount of adhesion and the internal friction angle resulting from the direct shear test increase with increasing percentage of glass fibers. After laboratory studies, the effects of using modified soil with improvement depths of one meter, two meters, four meters for strip foundations with widths of 0.75, 1.50 and 2.25 meters with the help of Plaxis2D software show that by increasing the percentage of mixing glass fibers In fine-grained clay soils, the amount of foundation deposition is reduced, while the reduction of foundation deposition on soil mixed with 0.8% glass fibers is more than soil mixed with 1% glass fibers. The reduction rate of the strip foundation with a width of 0.75 m with a mixing percentage of 0.8 glass fibers and a depth of improvement of 4 m is 1.57 cm. ،he reduction rate of the desired foundation with widths of 1.5 and 2.25 meters is equal to 2.29 and 2.72 cm, respectively

Due to the thickness and low weight of the parts made of glass reinforced concrete, it is impossible to use reinforcement in the manufacture of these products. For this purpose, glass fibers are used to improve the concrete behavior under tensile and flexural loads and to increase the toughness. Glass fiber reinforced concrete can be used to make parts in different shapes and designs.This paper uses glass fibers and pozzolanic materials with different percentages. In order to investigate the flexural strength and toughness indices of concrete produced by pre-mixing and spraying methods, 15 mixing designs containing different percentages of glass fibers and pozzolanic materials in pre-mixed method and 14 mixing designs with spraying method have been tested. All mixing schemes were also tested at 350, 650 and 1000 ° C and the results were analyzed by scanning electron microscope (SEM). The use of pozzolanic materials in specimens reinforced with glass fiber improves the modulus of rupture. The modulus of rupture in the presence of heat and in the event of a fire is greatly reduced, which is a better performance for controlling this reduction process. Also, the flexural strength of high-temperature samples (1000 ° C) can be significantly increased by using methaquoline at different percentages of 10 and 15%.

This study investigates the effect of steel fibers and its hybrid form with glass fiber on the properties of cement composites. The studied mechanical properties included compressive strength and flexural strength, and the energy absorption rate of the specimens was determined by the flexural toughness. In the mixtures, Portland cement and calcium aluminate have been used as bonding agents the mixes containing 2% steel fiber (% of total volume of the mixture), 2% AR Glass fiber, and hybrid of these fibers were made of glass fiber (2% steel fibers and 2% glass fiber), the length of these fibers was 25 mm. The compressive strength test was performed at the age of 1, 7, 28 and 90 days. Speciments made with calcium aluminate cement had higher compressive strength due to quick formation of microstructure compared to Portland cement mixtures, so that 90-day compressive strength of Portland cement mix was lower compared to the 1-day compressive strength of Calcium aluminate concrete. Incorporating 2% steel fibers also had a slightly enhancing effect on compressive strength. Flexural strength test was carried out at 28 and 90 days. The steel fibers create appropriate mechanical bond with the cementitious matrix, and the ultimate flexural strength was about 2 times higher than non-fibers specimen, due to the congrated geometry of the steel fibers. Substituting glass fiber also increased the ultimate flexural strength due to the high aspect ratio glass fibers and the well formed Interfacial transition zone (ITZ). The hybridization of the aforementioned fibers with steel fibers increases the bending strength due to the synergistic effect. The energy absorption content of the cementitious mix measured by flexural toughness index shows that this energy absorption content increases with the hybridization of the glass and steel fibers, so that the hybrid specimen made with Portland cement had a flexural toughness of 34.4 Nm. The glass fiber increased the toughness due to its excellent energy absorption. The steel fibers in the mixed increased the area under the flexural loading cureve and prevent the mixture from being destroyed by the first crack. In the shrinkage test results the control specimen with the two types of cements did not differ significantly, but the addition of 2% of the fibers (steel fiber and glass fiber) reduced shrinkage by their limiting effect on length change and propagation of micro cracks. When the percentage of glass fiber become higher, similar to the hybrid mix, the shrinkage was reduced further. This experiment was performed uo to 270 days and it was observed that the shrinkage of the hybrid specimen made with Calcium aluminate cement reduced by 65.5% compared to the plain concrete. In this study, the RCMT was carried out at 90 days. The results indicate that the penetration rate of the hybrid specimens and the glass fiber mixtures were lower than those of the steel fibers incorporated mixed. Also, in comparing two types of calcium aluminate cement and Portland cement, specimen made with calcium aluminate cement, the chloride ion penetration was lower than those made with Portland cement due to the improved Interfacial transition zone (ITZ) and less porosity of this type of cement.

Flexural behavior investigation of concrete materials is one of the most important issues in evaluating its mechanical behavior and is one of the main criteria for the design of concrete structures. The flexural behavior analysis of concrete specimens in a laboratory can simulate the behavior of concrete in a real scale with acceptable accuracy. Flexural strength, failure energy, bending coefficient and toughness are parameters that can be extracted from concrete bending results. Each of these parameters is important in the complex and sensitive design of high-rise or non-structural structures. In this research, two pozzolans of zeolite and silica ash, as well as two types of steel and glass fibers are used to improve the concrete specificationsThe effect of individual behavior of these materials and their effects simultaneously has been highlighted. The materials used in this project have a significant research background. However, in the combination of materials mentioned, little research has been done; and there are still more studying points. The results of pre-loading concrete fibers represented new aspects of concrete behavior in structural performance. It was observed that in the non-pozzolan specimens, increasing the amount of steel fibers increased flexural strength while increasing the amount of glass fibers did not have a significant effect on increasing flexural strength. Also, in the specimens with mixed pre-loading, with the decrease of the percentage of silica soot, the difference of results is reduced. This trend indicates that zeolite has a more important role in repairing cracks for shorter time intervals. Examination of fracture energy showed that specimens containing 1% steel fiber had the highest fracture energy due to fiber performance. After the specimens are damaged, this process is maintained and it seems that cracking in the fiber specimens does not necessarily lead to disruption of fracture energy changes.

Attitude to the current status of the asphalt mixtures performance in road pavement and cracking failures show that traditional asphalt materials can not meet the environmental and heavy traffic requirements and innovation should be created by knowledge and experience technologies of the new strategies and application of new materials in the industry.
Fiber asphalt is provided in the country because of production of fiber types in the recent years in the country and it provides the possibility of recycling asphalt and reductions of cost implementation; therefore, research in the application of this technological material in of technical and economical terms could solve the problem and can be a starting point of this approach for using these materials.
In this article, the fiber manufacturing industry is introduced in brief, the previous research about this kind of materials are investigated. The results show that increase in glass and carbon fiber can improve resistance of asphalt mixture by %15, but excessive use of them has a negative effect. The results show that the modulus of elasticity of asphalt mixture with fiber %15 is higher than asphalt mixture without fibers. Mechanical structure of asphalt fibers were also examined.

Using of Geotextiles is a solution to retard reflective cracking. In the recent decades, it has been concluded that by using of more resistant fibers such as glass fiber, it is possible to enhance the efficiency of Geotextiles. In this research, four points flexural beam test has been carried out to evaluate the effect of Geotextiles, which are reinforced by glass fibers, on fatigue life of asphalt specimens. There are three types of Geotextiles having the same type of fabric but different amount of glass fibers. It is shown that, in high strain cases, glass fibers are less efficient and therefore, it is much better using them at heavy traffic roads.