Polypropylene Fiber Length Research Articles

Influence of polypropylene fiber length and geometric shape on the compressive strength of cemented lepidolite tailings backfill

Lepidolite ore contains abundant lithium resources; however, the extraction process generates a large number of tailings, which are environmentally hazardous solid waste. Currently, cemented fiber reinforcement and tailings filling technologies are commonly used methods for tailings treatment. The fiber length and geometric shape significantly affect the performance of fiber-reinforced cemented lepidolite tailing backfill (CLTB). However, there is limited research on the impact of these two factors on the performance of CLTB. Consequently, Polypropylene fiber-reinforced CLTB of four sizes and four fiber lengths were prepared and used for uniaxial compressive strength (UCS) tests. The max UCS of fiber-reinforced CLTB was 2.84 MPa, and the maximum increase percent was 83.7% compared with the non-fiber-reinforced CLTB. The experimental results show that when the fiber length was 12 mm the CLTB had the maximum UCS, longer fibers did not necessarily result in a higher UCS. The end effect was significant when the difference in cross-sectional area was small. The UCS of the L-40 sample was higher than that of the Y-50 sample under the same fiber length. The differences in the size effect and geometric shape were the main factors influencing their mechanical performance. When the fiber length was from 0 mm to 6 mm, the size effect was obvious, the UCS values gradually decreased with an increase in the volume ratio and cross-sectional area. However, the fiber length was the primary factor influencing the fitting curve of the UCS when the fiber length was from 12 mm to 19 mm. Additionally, the addition of fibers enhanced the integrity of CLTB. In other words, fiber-reinforced CLTB exhibited improving structural integrity. This study can provide theoretical references for the research and practical applications of fiber-reinforced fillers and size effects, as well as the treatment of lepidolite tailings, while also reflecting the CLTB performance under the action of different sizes and different fiber lengths, improving the filling efficiency, mining, and backfill safety.

Effects of cement content, polypropylene fiber length and dosage on fluidity and mechanical properties of fiber-toughened cemented aeolian sand backfill

Effects of cement content, polypropylene fiber length and dosage on fluidity and mechanical properties of fiber-toughened cemented aeolian sand backfill

Effect of Varying The Content And Length Of Fibers In The Behavior of A Cemented Soil Efecto del Contenido de Fibra y la Variación de Longitud en el Comportamiento de un Suelo Cementado

This study presents the results of the effects of variation in the content and length of polypropylene fibers, when inserted into a soil-cement mixture, aiming its use as a primary coating for dirt roads. In this study, the experimental models were used: 5% fast-curing cement, clay sand of the Barreiras geological formation and polypropylene fibers of 6 mm and 24 mm lengths, at levels from 0.25%, 0.50% and 0.75% relative to the total dry soil-cement mass. After completion of the unconfined compression tests and tensile strength by diametrical compression, it was found that increasing fiber content in the soil-cement matrix provides: increase in resistance of the materials, increase on the voids content and the strain, but, significantly reduces the initial tangent modulus making the more ductile material. In the terms of length, it observed clearly that the 24 mm fiber has a stronger influence on the mechanical behavior when inserted into the matrix of the developed composite material.

Influence of key design variables on dynamic material properties of iron tailing porous concrete under impact loading

Iron tailing porous concrete (ITPC) is a new foamed concrete material that using iron ore tailing powder to partially replace the cement. Previous investigations on ITPC primarily focused on its mechanical properties under static loads or low strain rate conditions, leaving a significant gap in its impact resistance performance at high strain rates. This study employed the split Hopkinson pressure bar (SHPB) to test ITPC specimens under impact loading with strain rate around 120 s−1. Density, water-binder (W/B) ratio, iron tailing powder content, polypropylene fiber length and content were taken as key design variables to prepare the ITPC specimens with different mix ratios and study their effects on the dynamic material properties of ITPC. Specifically, the failure modes, stress-strain relations, elastic moduli, compressive strengths and energy dissipation densities of the ITPC specimens with various design variables were recorded and compared. The test results indicate that the material density, fiber length and content have strong influences on the impact failure modes of ITPC. The elastic modulus, compressive strength and energy dissipation density of ITPC exhibit exponential growth with the material density. These parameters, however, show an initial growth followed by a decrease with the rising W/B ratio, fiber length and fiber content, and they reach the peak values at around 0.70, 9 mm and 2.0%, respectively. Moreover, the iron tailing powder content of 25% is recommended for ITPC for maintaining good impact resistance.

About Dynamics of Improving the Foam Concrete Technological and Operational Properties upon Disperse Reinforcement with Polypropylene Fibers

Introduction. The efficiency of the foam concrete products manufacture and application in construction is briefly overviewed. The reasons constraining the nomenclature of the manufactured products are listed. The information about evolvement of the foam concrete disperse fiber-reinforcement technology is provided. The need for scientific research aimed at studying the dynamics of the foam concrete technological and operational properties upon disperse reinforcement with polypropylene fibers is formulated.Materials and Methods. The composition and properties of the materials used for manufacturing the foam concrete mixtures are listed. The methods used for assessing the technological and mechanical properties of the materials under study are indicated.Results. The results of the experimental assessment of the polypropylene fiber length and amount influence on the dynamics of the plastic strengthening growth of the equally dense foam and fiber-reinforced concrete mixtures are presented. The scope of the polypropylene fiber influence on the dynamics of the studied mixtures plastic strengthening is analysed. The scientific substantiation of the reasons accelerating the mass transfer processes during the disperse reinforcement of mixtures with fibers is given. The results of the bending tensile strength tests of the large-size D600 concrete specimens are presented.Discussion and Conclusion. The efficient positive influence of the polypropylene fiber, in correlation with its length, on the following foam concrete properties has been distinguished:speed of phase transfer;ultimate extensibility;elasticity and strength modulus of D600 concrete.

Effect of Content and Length of Polypropylene Fibers on Strength and Microstructure of Cementitious Tailings-Waste Rock Fill

The mechanical strength properties of cemented tailings backfill are very important for the safe and environmentally friendly mining of mineral resources. To check the impact of polypropylene fiber on strength and microstructure of cementitious tailings waste rock fill (CTWRF), diverse fiber lengths (6 and 12 mm) and dosages (0-control specimen, 0.3, 0.6, and 0.9 wt.%) were considered to prepare fiber-reinforced CTWRF (FRCTWRF) matrices. Experiments such as UCS (uniaxial compressive strength), X-ray CT (computed tomography), and SEM (scanning electron microscopy) were implemented to better characterize the backfills studied. Results showed that UCS performance of FRCTWRF was the highest (0.93 MPa) value at 6 mm fiber long and 0.6 wt.% fiber content. The peak strain of FRCTWRF was the highest (2.88%) at 12 mm fiber long and 0.3 wt.% fiber content. Growing the length of fiber within FRCTWRF can reduce its fracture volume, enhancing the crack resistance of FRCTWRF. Fiber and FRCTWRF are closely linked to each other by the products of cement hydration. The findings of this work will offer the efficient use of FRCTWRF in mining practice, presenting diverse perspectives for mine operators and owners, since this newly formed cementitious fill quickens the strengths required for stope backfilling.

Effects of Polypropylene Fibers on the Frost Resistance of Natural Sand Concrete and Machine-Made Sand Concrete.

In order to study the effect of polypropylene fibers on the frost resistance of natural sand and machine-made sand concrete, polypropylene fibers (PPF) of different volumes and lengths were mixed into natural sand and machine-made sand concrete, respectively. The freeze–thaw cycle test was carried out on polypropylene-fiber-impregnated natural sand concrete (PFNSC) and polypropylene-fiber-impregnated manufactured sand concrete (PFMSC), respectively, and the apparent structural changes before and after freezing and thawing were observed. Its strength damage was analyzed. A freeze–thaw damage model and a response surface model (RSM) were established used to analyze the antifreeze performance of PFMSC, and the effects of the fiber content, fiber length, and freeze–thaw times on the antifreeze performance of PFMSC were studied. The results show that with the increase in the number of freeze–thaw cycles, the apparent structures of the PFMSC gradually deteriorated, the strength decreased, and the degree of freeze–thaw damage increased. According to the strength damage model, the optimum volume of PPF for the PFNSC specimens is 1.2%, and the optimum volume of PPF for the PFMSC specimens is 1.0%. According to the prediction of RSM, PFNSC can maintain good antifreeze performance within 105 freeze–thaw cycles, and when the PPF length is 11.8 mm, the antifreeze performance of PFNSC reaches the maximum, its maximum compressive strength value is 33.8 MPa, and the split tensile strength value is 3.1 MPa; PFMSC can maintain a good antifreeze performance within 96 freeze–thaw cycles. When the length of PPF is 9.1 mm, the antifreeze performance of PFMSC reaches the maximum, its maximum compressive strength value is 45.8 MPa, and its split tensile strength value is 3.2 MPa. The predicted values are in good agreement with the measured values, and the model has high reliability.

Hollow-Fiber Liquid-Phase Micro-Extraction Method for the Simultaneous Derivatization, Extraction, and Pre-concentration of Organotin Compounds from Packed Fruit Juices

Organotin compounds are widely employed as pesticides and fungicides in agriculture and as stabilizers for the industrial manufacture of polyvinyl chloride and other polymers. Accordingly, these endocrine disruptors can be found in a variety of foods and beverages. In the present study, we describe the optimization of a hollow-fiber liquid-phase micro-extraction approach for the simultaneous derivatization, extraction, and pre-concentration of butyltin species from commercial fruit juices with the aim of investigating their migration from the packaging. The best extraction efficiencies were achieved by using hexane as the acceptor solvent and a polypropylene fiber length of 2 cm, whereas the agitation speed, extraction temperature, and total extraction time were set at 1100 rpm, 25 ºC, and 10 min, respectively. Using these optimal conditions, the method was satisfactorily validated in terms of linearity (5–1000 µg L−1), limits of detection (0.8–1.8 µg L−1), recovery (80.5–92.1%), intraday precision (10.2–13.1%), inter-day precision (11.0–15.5%), matrix effect (83.2–91.8%), accuracy (85.2–95.2%), specificity, and carryover. The application of this technique to commercial samples obtained from a local market demonstrated that levels of organotin species in packed fruit juices are negligible, in agreement with the limits established by the European Food Safety Authority (0.14 mg of total organotin compounds per kg of food).

Ultrasonic Pulse Velocity Test on Hybrid Fiber Reinforced Concrete

Concrete is a material of high importance in infrastructure and development projects. Concrete is characterized as a brittle material. In order to minimise the brittle failure, it is beneficial to add the fibers to the concrete mix without compromising the quality of concrete. The length of polypropylene fibers (PPF) and steel fiber (SF) used in concrete mixtures are 50mmand 35mmrespectively. The aimof this paper is to learn the quality of concrete and dynamic modulus of elasticity by using Ultrasonic Pulse Velocity (UPV). The percentages of polypropylene fiber are 0%, 0.3%, 0.6%, 0.7%, 1% and steel fiber are 0%, 0.1%, 0.4%, 0.7%, 1%. Comparison of conventional and Hybrid fiber-reinforced concrete (HFRC) is studied further. Experimental investigation is carried out on 18 cubes of M40 grade concrete of size 150X150X150mm for Ultrasonic Pulse Velocity (UPV) and compression test. The results show that conventional as well as fiberreinforced concrete are of excellent and of good quality with 28-day strength of 60.74 MPa. Conventional concrete has the highest pulse velocity and dynamic modulus of elasticity of 5.1903 5Øß5Ø‘Ü and 62.43 GPa. Next to it C-3-5 has a pulse velocity of 4.886 5Øß5Ø‘Ü, dynamic modulus of elasticity as 48.61 GPa and compressive strength of 61.77 MPa. Among FRCs Polypropylene fiber-reinforced concrete with 1% fiber volume fraction showed appreciable value of pulse velocity and elasticmodulus. In hybrid fiber-reinforced concrete C-3-3with 0.7%SF and 0.3% PPF has proven to have better quality as compared with other HFRCs.

Effect of polypropylene fiber length on mechanical and thermal properties of autoclaved aerated concrete

In this experimental study, the effect of polypropylene fiber (PF) length on the thermal conductivity, pressure and flexural strength values ​​of autoclaved aerated concrete (AAC) was investigated. The investigation used samples from G2/04, G3/05, and G4/06 classes AAC manufacturing in three different density and compressive strength groups. PF of three different lengths, 3, 6, and 12 mm, were chosen as reinforcement material, and AAC samples were made by adding 1.0% in the same volumetric ratios into the matrix material, taking into consideration their specific gravity. After the samples were kept in curing at 60 °C for 4 h, they were cured in an autoclave at 180 °C at 11 bar pressure for 7 h. After the autoclave process was completed, the flexural and compressive strength, thermal conductivity values of the samples were tested and the internal structure images were examined with a scanning electron microscope (SEM). It was observed that the flexural and compressive strengths of the samples increased with PF reinforcement in all density groups, while the thermal resistances decreased and the fiber length (for 3, 6 and 12 mm) had a positive effect on the compressive and flexural strengths of all examined AAC classes. It was obtained by 70.4% increase in the compressive and flexural strengths of G2/04 class of AAC samples with 12 mm length PF addition. As the PF length increases, the thermal conductivity values ​​of all samples also increase and the highest thermal conductivity increase was observed in the G5/06 class samples with a value of 20.2%. In general, it was observed that the compressive strength, bending strength and thermal conductivity values ​​of all samples increased depending on the increase in PF length. It has been observed that thermal conductivity values are worsen at more higher rates while the strength values of AAC at all fiber lengths is improves with PF additive.

Effect of nano-modification and fiber-reinforcement on mechanical behavior of cement-stabilized dredged sediment

This study investigates the mechanical behavior of cement-stabilized dredged sediment (CDS) improved by nano-MgO (NM) and polypropylene fiber (PF). The effects of NM content, PF content and PF length on the mechanical behavior of NM-modified and PF-reinforced CDS (CNPDS) were evaluated by conducting unconfined compressive strength (UCS, qu ) and splitting tensile strength (STS, qt ) tests. Furthermore, optical microscope scans were conducted to detect the interface friction evolution. The results indicated that adding NM can significantly improve UCS and STS of CDS, and the optimum NM content was 1.2%. The optimum PF content tended to increase with increasing curing age, and the 3 mm-length PF was the most effective in improving UCS and STS. Increasing NM content mainly increased the strength, but had little influence on ductility. The inclusion of PF can effectively improve the ductility of CNPDS, and contributed to its tensile strain-hardening characteristic. The relation of was obtained regardless of other influence factors. The combination of NM-modification and PF induced “bridging” effect provided a coupling effect inside CNPDS, and a concept model representing this process was established. The key findings in this study can be used as an effective method for dredged sediment stabilization in practical engineering.

Research on compressive strength of hybrid fiber reinforced concrete based on orthogonal design

The influence of steel fiber and polypropylene fiber mixed on compressive strength of high performance concrete (HPC) was studied. The steel fiber content (0.5%, 1.0%, 1.5%, 2.0%) (volume fraction, the same below), polypropylene fiber content (0.05%, 0.1%, 0.15%, 0.2%) and length (5mm, 6.5mm, 12mm, 18mm) were studied by L16 (45) orthogonal test for 28d ages, the range analysis and variance analysis of the test results are carried out, and the prediction model of compressive strength of hybrid fiber reinforced concrete was established. The results show that: The significant influence factor of concrete compressive strength is the volume fraction of polypropylene fiber, while the length of polypropylene fiber and the volume fraction of steel fiber are not significant; the concrete compressive strength with polypropylene fiber shows negative hybrid effect; The prediction model of compressive strength of hybrid fiber reinforced concrete has high accuracy, and the average relative errors is 2.96%.

Orthogonal Analysis on Mechanical Properties of Basalt-Polypropylene Fiber Mortar.

Orthogonal test method was applied to analyze the strength properties of basalt-polypropylene mortar. The effect of basalt fiber length, polypropylene fiber length, basalt fiber volume content and polypropylene fiber volume content on the 28 d cube compressive strength and flexural strength were investigated. Test results show that comparing with flexural strength, the influence of basalt fiber length and polypropylene fiber length on compressive strength of mortar was greater than on flexural strength. The length of polypropylene fibers contributes the highest to the flexural strength. The effect of basalt fiber on mortar strength is the largest with 6 mm length and 4% content. Polypropylene fiber length has the greatest influence on the compressive strength of fiber mortar, followed by basalt fiber volume content. Volume content of polypropylene fiber has the greatest influence on flexural strength of fiber mortar, followed by polypropylene fiber length. According to the scoring of the efficacy coefficient method, the best ratio combination for compressive and flexural strength was the basalt fiber length of 9 mm, polypropylene fiber length of 6 mm, basalt fiber volume content of 4% and polypropylene fiber volume content of 4%. Compared with the blank samples, the 28 d compressive strength and 28 d flexural strength of the cement mortar samples were increased by 27.4% and 49% respectively. According to the test results, the properties of the fiber were analyzed and evaluated and the mechanism of fiber action and fiber microstructure were analyzed.

Behavior of Cohesive Soil Reinforced by Polypropylene Fiber

For any land-based structure, the foundation is very important and has to be strong to support the entire structure. In order for the foundation to be strong, the soil underneath it plays a very critical role. Some projects where the soil compacted by modifying energy is insufficient to achieve the required results, so the additives as a kind of installation and reinforcement are used to achieve the required improvement. This study introduces an attempt to improve cohesive soil by using Polypropylene Fiber instead of conventional kinds used in soil stabilization. Three different percentages (0.25%, 0.5%, and 0.75% by dry weight of soil) and lengths (6, 12, and 18) mm of fiber are mixed with cohesive as a trial to enhance some properties of clay. The results of soil samples prepared at a dry density at three different water conditions (optimum water content, dry side, and wet side) showed that the increase of the percentage and length of polypropylene fiber causes a reduction in the maximum dry density of soils. Soil cohesion increases with the increase of PPF up to 0.5% then decreased. The length of Polypropylene fiber has a great effect on the cohesion of soil and adding 0.5% Polypropylene fibers with a length of 18mm to the soils consider the optimum mix for design purposes to improve the soil. Finally, the soil reinforced by PPF exhibits a reduction in the values of the compression ratio (CR) and accelerates the consolidation of the soil.

The impact of the length of polypropylene fibers on selected properties of concrete

The impact of the length of polypropylene fibers on selected properties of concrete

A Study on Freeze-Thaw Behavior of Randomly Distributed Fiber-Reinforced Soil

The freeze-thaw behavior and compressive strength of soil play a significant role in various engineering applications, such as dams and clay liners in waste containment facilities. The discrete fiber reinforcement technique was proposed in order to increase the soil’s freeze-thaw behavior and its compressive strength. In this study, a series of unconfined compression and freeze-thaw tests were carried out in the laboratory in order to investigate the eects of randomly distributed polypropylene fibers with a length of 3 mm, 6 mm, and 12mm on a soil. Fiber percentage for each length was determined as 0.15%, 0.20%, and 0.25% of the total dry weight of the reinforced soil. The number of freeze-thaw cycles was taken as 1, 3, 5, and 10. The results of the study indicate that an increase of polypropylene fiber length caused an increase in peak stress values. On the other hand, the peak stress of unreinforced and reinforced soil samples generally decreases when the number of freeze-thaw cycles is increased. Samples reinforced with polypropylene fibers usually behave in a more ductile manner than unreinforced samples.

The Mechanical Properties of Polypropylene Fiber Reinforced Polymer Modified Cement Mortar

Combining the effect of polypropylene fibers, such as the decrease of cement base material shrinkage and plastic crack, and the increase of material toughness, with the improvement of polymer on the interface between the fiber and matrix, both polypropylene fibers and polymer modifier were used in the cement mortar at the same time to make more excellent cement mortar materials. The improvement for cement mortar from different length of polypropylene fiber, polymer modifier (waterborne epoxy emulsion), mineral powder and silica ash were studied. Results showed that compared with the short fiber, the long fiber has a more obvious effect on the toughness, the best dosage of which is 0.6 kg/m3; the waterborne epoxy emulsion improved the bonding properties of interface between polypropylene fiber and cement mortar matrix, and then, long fibers improved flexural strength of cement mortar greatly, in terms of short fiber, effect is not manifest; With the increase of mineral powder, all the mechanical index of polypropylene fiber reinforced polymer modified cement mortar were improved and the effect of silica ash was better than that of mineral powder, the optimal replacement ratio were 0.1 and 0.3 respectively.

Efficacy of Resinous Polypropylene (PP) Fibers on Strength Behavior of Reinforced Soils

In the current study, Laboratory uniaxial compression tests are carried out in order to determine the strength and mechanical behavior of silty sand reinforced with randomly distributed short resinous Polypropylene (PP) fibers. The stress-strain behavior of composite materials is investigated through varying the number and length of PP fibers. In order to study the effects of the length and weight percent of fibers on the results of the uniaxial compressive strength, tests were accomplished on specimens with three different lengths and weight percentages of fibers. The results demonstrate increasing weight percent of fibers, in a constant length, leads to increase the maximum strength. Meanwhile, increasing the length of fibers, in a constant weight percent, reduces the maximum strength. Moisture absorbency of fibers which was about 120% at first, however, could be reduced to just 9% by using the epoxy polyamide resin. Moreover, the resin causes more interaction between sand aggregates and fibers leading to a higher internal friction angle.

Analysis of Crack Resistance for Hybrid Fiber Mortar

Due to the poor reproducibility of traditional plate method, the new knife-edge binding method is chosen to study the effects and the impact law in the crack resistance of the cement mortar with fiber in it. Mortar specimens with an equal volume of ash (0.1%) single-doped, mixed-doped polypropylene fiber and basalt fiber compared to the plain matrix mortar specimens on cracking performance tests within 24h. The results showed that: For the single-doped specimen, the longer the fiber the more excellent of its crack resistance, 30mm basalt fiber mortar improves the cracking performance by 99.1%; for the mixed-doped specimen, with the similar length of polypropylene fibers and basalt fiber mixed in have the optimal performance,the cracking performance improves 99.5%; With mixed fiber types (three kinds of fiber mixed-doped) increasing, although the specimen crack resistance decreased, but still increase the rate of 75.6% in the cracking performance.

고강도 콘크리트 내화피복용 경량 모르터의 온도이력 성상

The spalling causes the sever reduction of the cross sectional area with the exposure of the reinforcing steel, which originates a problem in the structural behaviour. By coating surface of high strength concrete with fireproof mortar, the high strength concrete is protected from the spalling in fire and the method to constrain the temperature increase of steel bar within the concrete. The purpose of this study is to investigate the temperature history properties of lightweight mortar using perlite and polypropylene fiber for fire protection covering material. For this purpose, selected test variables were the contents and length of polypropylene fiber. As a result of this study, it has been found that addition of polypropylene fiber to mortar modifies its pore structure and this causes the internal temperature to rise. And it has been found that a new lightweight mortar can be used in the fire protection covering material.