Inclusion Of Polypropylene Fibers Research Articles

Special features of treatment of cotton-polypropylene yarn in knitted fabric production

The process of cotton-polypropylene yarn treatment in knitted-fabric production is investigated. Based on analysis of the properties of cotton-polypropylene yarn vis-a-vis the properties of cotton yarn, the major directions of enhancing accuracy and stability of knitting in the process of treatment of yarn with inclusion of polypropylene fibres are established.

Effect of Random Inclusion of Polypropylene Fibers on Strength Characteristics of Cohesive Soil

This paper presents the effect of random inclusion of polypropylene fibers on strength characteristics of soil. Locally available cohesive soil (CL) is used as medium and polypropylene fibers with three aspect ratios (l/d = 75, 100 and 125) are used as reinforcement. Soil is compacted with standard Proctor’s maximum density with low percentage of reinforcement (0–1% by weight of oven-dried soil). Direct shear tests, unconfined compression tests and CBR tests were conducted on un-reinforced as well as reinforced soil to investigate the strength characteristics of fiber-reinforced soil. The test results reveal that the inclusion of randomly distributed polypropylene fibers in soil increases peak and residual shear strength, unconfined compressive strength and CBR value of soil. It is noticed that the optimum fiber content for achieving maximum strength is 0.4–0.8% of the weight of oven-dried soil for fiber aspect ratio of 100.

Fracture Property of Mass Concrete with Inclusion of Fibers

In order to obtain the effect of fibers on fractural property of mass concrete, it had investigated physical performance, elastic modulus and bending toughness of mass concrete with the presence of steel fiber and polypropylene fiber(PPF). Results showed that the inclusion of PPF caused a slight decrease in initial cracking strength, flexural strength and elastic modulus, yet resulted in small increase in equivalent flexural strength, capacity-carrying loading variation coefficient and toughness.The presence of steel fiber was of significance to increase initial-cracking strength, flexural strength and equivalent flexural strength, and produced a slight increase in elastic modulus and significant improvement in capacity-carrying variation coeffecient and flexural toughness. Overall, the inclusion of steel fiber is rated better than PPF in improving ductility and crack resistance of concrete.

Experimental study of lightweight expanded polystyrene aggregate concrete containing silica fume and polypropylene fibers

We developed a new structural lightweight concrete by totally or partially replacing coarse and fine aggregates in high performance concrete by expanded polystyrene (EPS) beads. In this work, the sizes of EPS bead were 1.0, 2.5 and 6.3 mm. Lightweight EPS concretes with a wide range of concrete densities and compressive strengths were successfully developed. Compressive strength, splitting tensile strength, shrinkage, and water absorption were examined. Additionally, fine silica fume (SF) and polypropylene (PP) fibers were added to improve the mechanical and shrinkage properties of EPS concretes. The results show that fine SF greatly increases the bond strength between the EPS beads and cement paste, thus increasing the compressive strength of EPS concrete. With inclusion of PP fibers, drying shrinkage properties are significantly improved.

High temperature resistance of normal strength and autoclaved high strength mortars incorporated polypropylene and steel fibers

The effects of high temperatures up to 900°C on normal strength, water cured and autoclave cured high strength mortars were investigated within the scope of this study. Mechanical properties such as, compressive strength, flexural strength, modulus of elasticity, and weight loss of the specimens were determined. The effect of polypropylene (PP) and steel fibers incorporation on high temperature behavior of high strength mortars were also investigated. Microstructure investigations were also carried out by SEM analyses. Test results indicated that compressive strength of all mixtures increased with increasing temperature up to 300°C. However, above 300°C all specimens showed explosive disintegration except normal strength mortars, and high strength mortars with PP fibers. It seems that, PP fiber inclusion is effective in preventing the explosive spalling behavior of high strength mortars. On the other hand, steel fibers did not improve high temperature resistance. To prevent spalling, minimum PP dosage for autoclave and water cured high strength mortars has been determined as 0.2% and 0.1%, respectively.

耐火性能向上を目的にポリプロピレン繊維を混入した高強度コンクリートの実用化および適用

One of the major concerns of High-strength concrete is its fire resistance. In some of our earlier high-rise RC projects, the most straight-forward measurewas taken to avoid the fire concerns : to provide additional finishing with normal-strength mortar layers all over the column surface. On the other hand, it has been known that the inclusion of polypropylene fibers improves the fire resistance of high-strength concrete by creating a pore structure that enables steam to dissipate. In this report, workability, compressive strength, durability, and fire resistance of the fiber concrete are summarized, and the application of such a concrete to an actual building construction is introduced.

Effect of fire on concrete and concrete structures

AbstractThe behaviour of concrete in fire depends on its mix proportions and constituents and is determined by complex physicochemical transformations during heating. Normal‐strength concretes and high‐performance concretes microstructurally follow similar trends when heated, but ultra‐high‐performance concrete behaves differently. A key property unique to concrete amongst structural materials is transient creep. Any structural analysis of heated concrete that ignores transient creep will yield erroneous results, particularly for columns exposed to fire. Failure of structural concrete in fire varies according to the nature of the fire; the loading system and the type of structure. Failure could occur from loss of bending or tensile strength; loss of bond strength; loss of shear or torsional strength; loss of compressive strength; and spalling of the concrete. The structural element should, therefore, be designed to fulfil its separating and/or load‐bearing function without failure for the required period of time in a given fire scenario. Design for fire resistance aims to ensure overall dimensions of the section of an element sufficient to keep the heat transfer through this element within acceptable limits, and an average concrete cover to the reinforcement sufficient to keep the temperature of the reinforcement below critical values long enough for the required fire resistance period to be attained. The prediction of spalling – hitherto an imprecise empirical exercise – is now becoming possible with the development of thermohydromechanical nonlinear finite element models capable of predicting pore pressures. The risk of explosive spalling in fire increases with decrease in concrete permeability and could be eliminated by the appropriate inclusion of polypropylene fibres in the mix and/or by protecting the exposed concrete surface with a thermal barrier. There are three methods of assessment of fire resistance: (a) fire testing; (b) prescriptive methods, which are rigid; and (c) performance‐based methods, which are flexible. Performance‐based methods can be classified into three categories of increasing sophistication and complexity: (a) simplified calculations based on limit state analysis; (b) thermomechanical finite element analysis; and (c) comprehensive thermohydromechanical finite element analysis. It is only now that performance‐based methods are being accepted in an increasing number of countries.

Effect of polypropylene fiber reinforcement on the properties of fresh and hardened concrete in the Arabian Gulf environment

The effect of polypropylene fiber reinforcement (0.2 % by volume of concrete) on the workability, plastic shrinkage, drying shrinkage and strength of concrete has been studied in a detailed test program. Concrete specimens of different mix designs with and without polypropylene fibers have been prepared, cured in laboratory conditions and hot weather environment of the Arabian Gulf, and then tested at different ages for the determination of various properties. The results indicate that the inclusion of polypropylene fibers eliminates the plastic shrinkage cracking of concrete, and reduces the drying shrinkage to some extent. It also slightly improves the tensile and flexural strength of concrete.