Adding Polypropylene Fibers Research Articles

Contribution of cocktail of polypropylene and steel fibres in improving the behaviour of high strength concrete subjected to high temperature

The aim of the study is to improve the understanding of the influence of a polypropylene and steel fibres cocktail on the behaviour of high strength concretes subjected to high temperature. Concrete mixes were studied by adding polypropylene fibres, steel fibres and cocktail of fibres. The concrete specimens were subjected to various heating–cooling cycles. The initial and residual mechanical properties, the porosity and the mass loss of the studied concrete mixes were investigated. Different concretes compositions with various amounts of polypropylene and/or steel fibres were tested. Experimental results show the significant improvement of the residual mechanical properties of concretes containing the cocktail of fibres compared to concretes without fibres.

Commingled natural fibre/polypropylene wrap spun yarns for structured thermoplastic composites

A major challenge for natural fibre composites is to achieve high mechanical performance at a competitive price. Composites constructed from yarns perform better than composites made from random nonwoven mats. However, the twist structure of conventional ring spun yarns prevents the full utilization of fibre mechanical properties in the final composites. We produced flax/polypropylene commingled wrap yarns in which all flax fibres were twistless. Composites made from the wrap yarn demonstrated significant improvement of flexural modulus. Most currently available low cost natural fibres, such as decorticated hemp, cannot be efficiently made into yarns because of their lack of cohesion. Adding polypropylene fibres to decorticated hemp improved textile processing performance. The polypropylene fibres served as a carrier for the natural fibres during processing and became the polymer matrix in the final composites.

섬유 혼입률에 따른 섬유보강 경량골재 콘크리트의 역학적 특성

This paper presents results of an experimental study conducted to investigate the effect of volume fraction of fibers on the mechanical properties of a fiber-reinforced, lightweight aggregate concrete(FRLAC) that was produced without an autoclave process. The FRLAC enhanced the strength of lightweight, cellular concrete by adding polypropylene fibers and lightweight aggregates. To investigate the effect of volume fraction of fibers on the mechanical behavior of FRLAC and to determine the optimal volume fraction of fibers, a series of compression and flexural strength tests on FRLAC specimens with various fiber volume fractions(0%, 0.10%, 0.25%, 0.50%) were conducted. It was observed from the tests that a 0.25% volume fraction of fibers maximized the increase in the strength of FRLAC and the fibers controlled cracking in FRLAC.

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...