Use Of Polypropylene Fibers Research Articles

Research of Polypropylene Concrete’s Pavement Performance

Emergence of commodity concrete and pumping concrete is a major development of modern concrete technology, it has high efficiency, high homogeneity and good environmental effects, etc. But, use of modern high performance concrete make the difficulty of controlling the early cracks increased, considering this problem, use of polypropylene fibers to test concrete shrinkage cracks, come to regularity of polypropylene fiber affect concrete shrinkage cracks early, in order to serve the synthetic fibers used in concrete better.

Enhancement of durability of concrete composites containing natural pozzolans blended cement through the use of Polypropylene fibers

A parametric experimental study of the effects of Polypropylene fibers (PPF) on early cracking due to drying shrinkage in concretes with Natural Pozzolan Cement (NPC) and its influence on its durability is presented.Concrete composites containing natural pozzolan (toba trachite), point shaped crushed aggregates and different fiber volume fractions of PPF (0.03%, 0.06%, 0.09%, and 0.12%) were studied. This mixture is characterized by high permeability and carbonation ranges.Early age cracking control ability and drying shrinkage of PPF in NPC concretes were measured under dry setting conditions. The cracked area due to drying shrinkage was measured to establish the positive effect of the different PPF volume fractions in concretes. Besides, bulk density and water permeability depth were determined. Finally these specimens were stored for two years and tested afterwards, measuring the natural carbonation depth. Then the cracking area was again measured to assess the control ability of PPF on this parameter after long time.Finally a relationship of these indicators is analyzed to understand future lifespan of these concrete composites.The results indicate that a volume fraction of 0.07% of PPF reduces cracking area due to drying shrinkage of NPC a 66%, but larger volume fractions did not increased linearly this effect, and even worse results were obtained. The increment of PPF volume fraction reduces the water permeability depth and even the carbonation depth. A reduction of the cracked area, due to early shrinkage, of a 66% in NPC concretes may reach in these concretes a 32% lower water permeability indicators (enclosed wet area) and a 43% shorter minimum carbonation depth attending to the results obtained.So it can be considered that the cracking control ability of fibers on the exposed concrete surface reduced water permeability and CO2 diffusion. However the use of fiber increased porosity and reduced bulk density and ultrasonic modulus of NPC concretes.In conclusion NPC concretes with low amounts of PP fibers (upper to 0.07% volume fraction) are less permeable and the CO2 diffusion is slower in time due to early age cracking control, producing more durable concretes.

Development, Field Testing, and Implementation of Improved Bridge Parapet Designs

Premature cracking of concrete bridge parapets is a potentially complex problem, with several possible causes. The objectives of this study were to determine the reasons for uncontrolled concrete bridge parapet cracking and to provide recommendations to the Ohio Department of Transportation to prevent such cracking in the future. Potential factors examined in this study included properties of the concrete mixtures used, construction methods, joint details, composite structural action, and durability of the concrete and reinforcement. A total of 22 test bridge parapets were or will be constructed as part of this project to evaluate different approaches to address premature bridge parapet cracking. Both the use of polypropylene fibers and deep saw cuts through glass fiber–reinforced polymer (GFRP) reinforcement provided positive results for preventing early-age cracking. The use of fibers prevented the occurrence of any shrinkage or temperature cracking even though the control joints did not appear to function as designed in early observations. Performing a deeper saw cut of 3½ in. (89 mm) and cutting through the horizontal GFRP reinforcement allowed the control joints to crack easily, mitigating cracking elsewhere on the parapet. The most optimal design of a bridge parapet thus far seems to be including GFRP rebar as the horizontal reinforcement in the parapet to make a deeper saw cut for the control joints. At this point, none of the cracks between joints that were observed during the previous forensic study have been found on these new bridges.

Effect of nano-particles on durability of fiber-reinforced concrete pavement

In this study frost resistance and mechanical properties of fiber-reinforced concrete pavement containing nano-particles are studied. Nano-particles are employed to be as substitute of a portion of cement. For comparison the frost resistance and mechanical properties of plain concrete (control concrete), concrete containing nano-particles (without fibers) and concrete containing polypropylene fibers are also experimentally studied separately in this work. The specimens were subjected to cycles of freezing and thawing in water according to ASTM C666A. Experimental results show that using 5% nano-silica (by the weight of cementitious materials) improves the compressive strength and frost resistance of concrete as much as 30% and 83% respectively. Substitution 3% of cement by nano-alumina particles can improve compressive strength and frost durability of concrete as much as 8% and 81% respectively. Experimental results also show that polypropylene fibers can slightly affect the frost durability and compressive strength of concrete. As a general result it can be concluded that using nano-particles incorporating polypropylene fibers enhances frost resistance and compressive strength of concrete pavement because of that the permeability and porosity of concrete are reduced due to the use of nano-particles and also the tensile strength of concrete is enhanced due to the use of polypropylene fibers.

섬유의류산업의 지속가능성 증진을 위한 의복종류별 방안 모색

Sustainable fashion & textile is more than eco fashion & textile with the concepts for the next generation's happiness, prosumer value, and community responsibility. This study considers methods to enhance fashion and textile industry sustainability in accordance to clothing types (material, product life and washing properties) and to investigate company strategies. Company strategies are of redesign with stock, volunteering & measuring trash amount, participation by evaluation stores, clerk environment education, hiring QC specialist and reinforcing partnerships. For the case of daily innerwear, throwing away and recycling is more efficient for the environment than laundering in the consumer use stage; subsequently, we recommend the use of polypropylene fiber (a cheap and an eco-friendly material) for this item that can be recycled and reformed after use. For the case of single layer clothing (such as sportswear, blouse or pants) we recommend the use of thermoplastic materials with welding or fuse assembling technology instead of a sewing method of seams as well as the recycle design that is simply melted and reformed into new clothing without an after use dissembling process. Secondhand use or resale is suitable for denim/jean items if the clothing has a storytelling or private history tag. Lastly, module-type jacket or coat shows the variety of styles with one clothing worn w/o collar or sleeve details and changed into vest/coat; in addition, it is possible to add or partly tear off some jacket/coat fibers of the felt material to reform it into a new design.

High Strength Polypropylene Fibre Reinforcement Concrete at High Temperature

Concrete is an inherently brittle material with a relatively low tensile strength compared to compressive strength. Reinforcement with randomly distributed short fibres presents an effective approach to the stabilization of the crack and improving the ductility and tensile strength of concrete. A variety of fibre types, including steel, synthetics, and natural fibres, have been applied to concrete. Polypropylene (PP) fibre reinforcement is considered to be an effective method for improving the shrinkage cracking characteristics, toughness, and impact resistance of concrete materials. Also, the use of PP fibre has been recommended by all of the researchers to reduce and eliminate the risk of the explosive spalling in high strength concrete at elevated temperatures. In this study, constitutive relationships are developed for normal and high-strength PP fibre reinforcement concrete (PPFRC) subjected to high temperatures to provide efficient modelling and specify the fire-performance criteria for concrete structures. They are developed for unconfined PPFRC specimens that include compressive and tensile strengths, elastic modulus, modulus of rupture, strain at peak stress as well as compressive stress–strain relationships at elevated temperatures. The proposed relationships at elevated temperature are compared with experimental results. These results are used to establish more accurate and general compressive stress–strain relationships prediction. Further experimental results for tension and the other main parameters at elevated temperature are needed in order to establish well-founded models and to improve the proposed constitutive relationships, which are general, rational, and fit well with the experimental results.

Influence of polypropylene fibre on the mechanical performance and durability of concrete materials

Concrete is the most commonly used structural material in the world. This paper evaluated the influence of polypropylene fibre on the performance of concrete materials. The performance of concrete materials was determined by testing the compressive, flexural, and splitting tensile strengths, as well as the freeze-thaw resistance, impermeability, and restrained shrinkage cracking. These results indicate that the use of polypropylene fibres can significantly improve the flexural and splitting tensile strengths of concrete materials. The freeze-thaw resistance and impermeability were improved due to the addition of polypropylene fibre. When the volume of the added polypropylene fibres was increased, the concrete was able to resist more freeze-thaw cycles. Polypropylene fibres can also reduce cracking, and improve the cracking resistance of concrete materials.

Evaluation of Fiber and Blast Furnace Slag Concrete Chloride Penetration through Computer Simulation

Durability of concrete is an important issue, and one of the most critical aspects affecting durability is chloride diffusivity. Factors such as water.cement ratio, degree of hydration, volume of the aggregates and their particle size distribution have a significant effect on chloride diffusivity in concrete. The use of polypropylene fibers(particularly very fine and well dispersed micro fibers) or mineral additives has been shown to cause a reduction in concrete's permeability. The main objective of this study is to evaluate the manner in which the inclusion of fiber(in terms of volume and size) and blast furnace slag(BFS) (in terms of volume replacement of cement) influence the chloride diffusivity in concrete by applying 3D computer modeling for the composite structure and performing a simulation of the chloride penetration. The modeled parameters, i.e. chloride diffusivity in concrete, are compared to the experimental data obtained in a parallel chloride migration test experiment with the same concrete mixtures. A good agreement of the same order is found between multi.scale microstructure model, and through this chloride diffusivity in concrete was predicted with results similar to those experimentally measured.

Investigation of tensile properties and dyeing behavior of various polypropylene/polyamide 6 blends using a mixture experimental design

Polypropylene has many advantages over other polymeric fibers such as high tensile strength, good abrasion resistance, high chemical resistance and very competitive price. However, the use of polypropylene fiber is restricted by the lack of affinity of conventional dyestuffs for this fiber. Many attempts have been made to improve the dyeability of polypropylene by various techniques. It must however, be noted that enhanced dyeability of polypropylene should not adversely impair its other properties, in particular its mechanical properties. To this end, in the present investigation, a mixture experimental design was used in order to attain an optimal region of proportions of three components namely polypropylene (PP), maleated polypropylene (polypropylene grafted with maleic anhydride (MAH-PP) as a compatibilizing agent) and polyamide 6 (PA6); where enhanced dyeability as well as retained mechanical properties would be achieved. Additionally, in order to analyze the morphology of the blends, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used. Finally, in order to evaluate effect of each component on fastness properties of the blends, wash, rub and light fastnesses were determined by the corresponding standard test methods.

The effect of polypropylene fibers on the properties of fresh and hardened lightweight self-compacting concrete

This paper evaluates the LECA Lightweight Self-Compacting Concrete (LLSCC) manufactured by Nan-Su, of which the Packing Factor (PF) of its design mixing method has been modified and improved. The study analyzes the impact of polypropylene fibers on LLSCC performance at its fresh condition as well as its mechanical properties at the hardened condition. The evaluation of Fiber Reinforced LLSCC (FR-LLSCC) fluidity has been conducted per the standard of second class rating of JSCE, by three categories of flowability, segregation resistance ability and filling ability of fresh concrete. For the mechanical properties of LLSCC, the study has been conducted as follows: compressive strength with elapsed age, splitting tensile strength, elastic modulus and flexural strength, all of which were measured after the sample being cured for 28 days. When self-compacting concretes were lightened to 75% of their normal weight, their fresh properties are affected immensely. Applying 0.3% volume fractions of polypropylene fiber to the LLSCC resulted in 40% reduction in the slump flow (from 720 mm to 430 mm). In general, the rate of slump flow over Super Plasticizer (SP) volume percentage reduced with the use of polypropylene fibers in the FR-LLSC. Polypropylene fibers did not influence the compressive strength and elastic modulus of LLSCC, however applying these fibers at their maximum percentage volume determined through this study, increased the tensile strength by 14.4% in the splitting tensile strength test, and 10.7% in the flexural strength.

Effect of perforated foil and polypropylene fibre covers on growth of early potato cultivars

This paper presents the results of a three-year research on the effect of perforated polyethylene foil and polypropylene fibre covers on the growth of early potato cultivars at various lengths of plant covering period (2 and 3 weeks after plant emergence). Plants grown under covers were higher, produced higher mass of above-ground parts, and were characterised by a smaller value of leaf weight ratio (LWR) and leaf area ratio (LAR) compared with the cultivation without covering. In the case of plant covering for 2 weeks after emergence the mass of leaves at the time of cover removal was on average almost 2 times higher and the mass of stems over 2.5 times higher than in the cultivation without covering; the values of LWR and LAR were however smaller by 0.094 and 0.137 m<sup/kg, respectively. At the 3-week period of plant covering the differences in the mass of above-ground parts were a little smaller than at 2-week period of plant covering, and LWR and LAR were 1.4 times and 2.3 times higher, respectively. The research showed a significant effect of type of cover used on plant growth. When perforated foil was used, plants were higher and produced more mass of above-ground parts compared with polypropylene fibre usage. The most favourable effect of perforated foil covering was observed in the year with the lowest air temperature in May; 2 weeks after plant emergence, the use of perforated foil resulted in the mass of leaves and stems 1.5 times and 2.2 times as high as with the polypropylene fibre, respectively. The differences were lower when plants were covered for 3 weeks. The use of polypropylene fibre resulted in higher LWR and LAR by 0.060 and 0.276 m<sup/kg, respectively, after 2 weeks from plant emergence, and by 0.072 and 0.328 m<sup/kg after 3 weeks from plant emergence.

The effect of polypropylene fibres within concrete with regard to fire performance in structures

PurposeThe purpose of this paper is to examine the effect of various polypropylene fibre additions (types and volume) to concrete with regard to explosive spalling when subject to high temperatures similar to those experienced in building or tunnel fires.Design/methodology/approachMedium strength concrete was manufactured with varying proportions of polypropylene fibres. Plain control samples were used to determine the original concrete strength and this was used as a benchmark following high temperature heat tests to evaluate the surface condition and final compressive strength. A pilot study was used to determine an appropriate heat source for the test. This was three Bunsen burners, however sufficient heat could not be generated within 150 mm concrete cubes and the concrete was shown to be a significant insulator and fire protection for structural members. The concrete test cubes were tested in a saturated condition which may reflect conditions where concrete is used in an external environment and thus is subject to soaking.FindingsOne hundred and fifty millimetre concrete cubes with and without fibres were placed into a furnace at 1,000°C. Explosive spalling was shown to be reduced with the use of polypropylene fibres but the final compressive strength of concrete was significantly reduced and had little residual structural value after a two hour period of heating.Research limitations/implicationsAs the concrete tested was saturated, this condition provided a worst case scenario with regards to the build up of hydrostatic and vapour pressure within the cube. A range of percentage moisture contents would produce a more evenly balanced view of the effects of fibres in concrete. A single grade of concrete was used for the test. As the permeability of concrete influences the rate at which steam can escape from the interior of a saturated concrete cube, testing a range of concrete strengths would show this aspect of material performance with regard to spalling and final residual strength. Further research is recommended with regard to moisture contents, strengths of concrete and a range of temperatures.Practical implicationsThis research has significance for the designer, in that buildings subject to terrorist activity may suffer from impact damage and an outbreak of fire following the initial attack.Originality/valueThe use of polypropylene fibres in concrete to provide anti spalling qualities is relatively new and this research adds to the knowledge regarding fibre type and volume with regard to first spall time, total area and number of areas subject to spalling and the final compressive strength of concrete following two hours of raised temperatures.

Effect of perforated foil and polypropylene fibre covers on assimilation leaf area of early potato cultivars

This paper presents the results of a three-year research on the effect of perforated polyethylene foil and polypropylene fibre covering at various lengths of plant cover period (2 and 3 weeks after plant emergence) on the assimilation leaf area of early potato cultivars. In the case of plant covering for 2 weeks after emergence the assimilation leaf area and leaf area index (LAI) at the moment of cover removal were on average 2 times higher than in the cultivation without covering; at the 3-week period of plant covering they were almost 1.7 times higher. A higher favourable effect of covering was obtained in the year with the lowest air temperature in May. The use of the covers at that time increased the assimilation leaf area and LAI 2.5 times and 3 times, respectively. The research showed no significant effect of the type of cover used on the assimilation leaf area and LAI; however, the specific leaf area (SLA) was higher with the use of polypropylene fibre.

High-Strength Self-Compacting Concrete Exposed to Fire Test

Results are presented from experimental work on the high-temperature behavior of conventional vibrated high-strength concrete and self-compacting high-strength concrete. Concrete cylindrical specimens and prismatic specimens were subjected to a low heating rate of 0.5°C∕min (up to 400°C ) and a high heating rate according to International Standard Organization 834 fire curve (up to 600°C ). The experimental results show that the residual mechanical properties in reference to initial mechanical properties of self-compacting high-strength concretes were similar to that of conventional high-strength concrete. The risk of spalling for self-compacting high-strength concrete was greater than that of conventional high-strength concrete. As for the conventional vibrated high-strength concrete, the use of polypropylene fiber improved the thermal stability of self-compacting high-strength concrete. Adding polypropylene fiber modified thermal gradient (in consequence thermal stresses) in the tested concrete specimen...

Production and use of polypropylene fibres and yarn

World production of PP fibres in 2004 was approximately 6.3 million tons, including 2.1 million tons of film fibres. The total consumption of PP fibres, including spunbond/meltblown, on the European continent increased by 2.5% in 2004, reaching 2.4 million tons. In the near future, expansion of use of PP fibres for production of nonwovens is projected. The world market capacity will increase by 2008 to 3.55 million tons, including up to 1.0 million tons in North American countries. A wide assortment of PP products in the form of films, ribbons, fibrillized materials, staple fibre, complex yarns, spunbond, meltblown, etc., for manufacturing bags, soft containers, agrotextiles, packaging, cables, carpets, hygienic and medical goods, etc., has been developed.

Use of Fibers and Welded-Wire Reinforcement in Construction of Slabs on Ground

Different types of fiber-reinforced concrete have been advocated and used as a replacement for welded-wire reinforcement (WWR) in slabs on ground, leading at times to conflicting opinion and/or unrealistic expectation about the benefits of using either WWR or different types of fiber in slabs. In order to verify some of these opinions, tests have been carried out on model slabs (2.5 m×2.5 m×150 mm thick) cast on grade in a test pit and loaded to failure. Results are compared to evaluate the load-carrying capacity for slabs having equivalent amounts of either WWR, fibrillated polypropylene fibers, or steel fibers. Test results show that steel fibers are a suitable alternative to using properly positioned WWR. However, use of polypropylene fibers at a low dosage, which is most common for slab construction (0.9 kg/m³), provides little benefit in terms of increased load-carrying capacity when compared with a plain unreinforced slab. Slab capacity is affected mainly by the postcracking strength of the concrete section, and results from flexure beam tests give a good indication of expected behavior of slabs. The test results also show that a poor subgrade support can be compensated by reinforcing a slab with a moderate amount of either WWR or steel fibers (at a dosage of 30 kg/m³).

Use of rubble from building demolition in mortars

Because of increasing waste production and public concerns about the environment, it is desirable to recycle materials from building demolition. If suitably selected, ground, cleaned and sieved in appropriate industrial crushing plants, these materials can be profitably used in concrete. Nevertheless, the presence of masonry instead of concrete rubble is particularly detrimental to the mechanical performance and durability of recycled-aggregate concrete and the same negative effect is detectable when natural sand is replaced by fine recycled aggregate fraction. An alternative use of both masonry rubble and fine recycled material fraction could be in mortars. These could contain either recycled instead of natural sand or powder obtained by bricks crushing as partial cement substitution. In particular, attention is focused on the modification that takes place when either polypropylene or stainless steel fibers are added to these mortars. Polypropylene fibers are added in order to reduce shrinkage of mortars, stainless steel fibers for improving their flexural strength. The combined use of polypropylene fibers and fine recycled material from building demolition could allow the preparation of mortars showing good performance, in particular when coupled with bricks. Furthermore, the combined use of stainless steel fibers and mortars containing brick powder seems to be an effective way to guarantee a high flexural strength.

Mechanical Properties and Freezing and Thawing Durability of Polypropylene Fiber-Reinforced Shotcrete Incorporating Silica Fume and High Volumes of Fly Ash

Abstract This paper describes the materials used, mixture proportions, mixing and shotcreting operation, and properties of the fresh and hardened polypropylene fiber-reinforced shotcrete incorporating silica fume and high volumes of fly ash. The polypropylene fiber-reinforced high-volume fly ash shotcrete produced had satisfactory workability, mechanical properties, and resistance to freezing and thawing cycling. The shotcrete containing silica fume had negligible rebound compared with that without silica fume. The incorporation of fly ash and silica fume improved the workability of the fresh shotcrete, and this resulted in lower operating pressure for the shotcreting. The use of polypropylene fibers up to 0.5% by the volume of the shotcrete did not affect significantly the compressive strength, and the shotcrete incorporating both fly ash and silica fume bonded well to the base concrete. The fiber-reinforced shotcrete showed satisfactory performance after 300 cycles of freezing and thawing with a durability factor >80 even though the air contents were relatively low, and the spacing factor L¯ was relatively high.

World production and use of polypropylene fibres and thread. A review

The existence of sources of accessible and inexpensive raw material has caused the turbulent development of PP fibres and thread. At present, they occupy third place in the world in production volume, after polyamide and polyester fibres and yarns, and could be in first place by 2000 based on the production growth rates. The cause of this rapid development is the relatively simple and ecologically “clean” technology and low production costs. Industrial production of PP fibres and thread is still concentrated in Western Europe, the US, and Japan, where 70% of all PP is produced. In the 1990s, the proportion began to decrease due to production in developing countries in South America, Asia, and Africa. Since the mid-1980s, PP fibre and yarn production capacity has increased, while the development of production capacities for film fibres and monofilaments has virtually stabilized. The areas of application of PP fibres and yarns are determined by their properties. Carpet manufacture is the largest and most developed area of their use. In the future, PP fibres and thread could move to first place in production of carpets, outstripping polyamide fibres; this could be due to the appearance of BSF PP yarns from DuPont (USA) on the world market. The increase in the market for PP floor coverings is related to their use in the automobile industry. Nonwovens from PP fibres are used in both the home and in industry (construction, agriculture, automobile, furniture, and shoe industries, etc.). Development of sanitary and hygienic nonwovens made of PP fibres has increased.

Effect of Fibers on Development/Splice Strength of Reinforcing Bars in Tension

The effects of fibers on development/splice strength of reinforcing bars in tension were experimentally investigated. Three series of tests, with five beams each, lap spliced at midspan, were carried out. The research parameters were: bar diameter (d sub b) fiber type, fiber volume fraction (V sub f), and fiber reinforcing index (V sub f L/d sub f). The beams were loaded in positive bending with constant moment along the splice region. The current experimental results demonstrated clearly that the use of hooked steel fibers in concrete matrixes increases significantly the development/splice strength of reinforcing bars in tension. While the use of polypropylene fibers, added in 0.6 percent by volume, improved the bond performance in the post-splitting range, they were not as effective as steel fibers in increasing the development/splice strength of the reinforcing bars.