Polypropylene Fibre Reinforced Cement Composites Research Articles

Relationship between microstructure and performance of polypropylene fibre reinforced cement composites subjected to elevated temperature

This article presents the investigation on mechanical and transport properties of polypropylene (PP) fibre reinforced cement composites with varying fibre volume (0.05–0.30%). Fresh property of the fibre reinforced concrete was evaluated through the flow table test, while hardened properties including compressive strength (1, 3, 7 and 28-day), and modified flexural strength, ultrasonic pulse velocity and water absorption were assessed at the 28-day. The effects of fibre addition on mechanical properties were evaluated at room temperature and 200 °C. Microstructural characterizations were performed using field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray spectroscopy (EDX). Micrographs of the failed PP fibre reinforced composites indicated that the increase in flexural strength at room temperature was attributed to the crack bridging and fibre debonding at the fibre/matrix interface. Higher water absorption value was achieved for PP reinforced composites subjected to elevated temperature compared to control mortar. FESEM/EDX analyses on the elevated temperature samples indicated that the increment was due to the growing of macro-pores from the empty space left behind by fibre settlement. In conclusion, the addition of PP fibres in the cement mortar adversely affect the strength when the composite is subjected to elevated temperature, but resulted in improved durability.

Seismic Performance of a Full-Size Polypropylene Fiber-Reinforced Cement Composite Bridge Column Based on E-Defense Shake Table Experiments

E-Defense shake table experiments on a 7.5 m tall, 1.8 m by 1.8 m square bridge column using polypropylene fiber-reinforced cement composites (PFRC) at the plastic hinge region and part of the footing is presented. The column was excited using 80% of the original intensity of the near-field ground motion recorded at the JR Takatori Station during the 1995 Kobe, Japan earthquake. Use of PFRC mitigated cover and core concrete damage, local buckling of longitudinal bars, and deformation of ties even after six times of repeated excitation. The damage sustained was much less than the damage of regular reinforced concrete columns.

폴리프로필렌섬유보강 시멘트 복합재료에 정착된 구조용 합성섬유의 부착거동에 미치는 섬유 혼입률의 효과

폴리프로필렌섬유보강 시멘트 복합재료와 구조용 합성섬유의 부착특성을 평가하였다. 폴리프로필렌섬유는 0.10%, 0.15% 및 0.20%의 체적비로 적용하여 dog-bone 시험을 실시하였다. 구조용 합성섬유와 폴리프로필렌섬유보강 시멘트 복합재료 사이의 부착강도는 폴리프로필렌섬유의 혼입률이 증가할수록 증가하였으나 0.20% 이상이 되면 감소하였다. 또한 폴리프로필렌섬유의 첨가는 계면인성과 마찰저항을 증가시킨다. 인발시험 후 구조용 합성섬유 표면의 미소구조 분석은 폴리프로필렌섬유의 혼입률이 증가할수록 긁힘 현상이 증가하였다. The bond properties between polypropylene fiber reinforced cement composites and structural synthetic fiber have been investigated. in this paper. Three levels of polypropylene fibers volume fraction were used, 0.10%, 0.15%, and 0.20% in a series of Dog-bone pull out tests. The bond strength between structural synthetic fiber and polypropylene fiber reinforced cement composites increases with the volume fraction of polypropylene fiber, but the bond strength decreases above the amount of 0.20% by volume of polypropylene fiber reinforced cement composites. Also, the addition of polypropylene fiber a significant improved the interface toughness and the frictional resistance, The microstructure of structural synthetic fiber surface was investigated after the pullout test. The scratched of structural synthetic fiber increased with the polypropylene fiber volume fraction.

CYCLIC STRESS-STRAIN RESPONSE OF POLYPROPYLENE FIBER REINFORCED CEMENT COMPOSITES

This study presents an investigation on the response of polypropylene fiber reinforced cement composites to uniaxial compression, tension and cyclic loading. A series of experiments were conducted on specimens 350 mm high with cross-section of 105 mm by 70 mm tapering to 70 mm by 70 mm at the center. The effects of cyclic loading on the stress-strain envelope including unloading and reloading paths in both compression and tension were examined. It is found that unloading and reloading do not essentially change the shape of the stress-strain envelope. Reverse cyclic loading affects the tensile response of the material if the uniaxial compressive strength during loading was exceeded and not to affect the tensile response if the compressive strength was not exceeded.

The effects of age up to 18 years under various exposure conditions on the tensile properties of a polypropylene fibre reinforced cement composites

An 18 year test programme has been completed on the tensile stress-strain performance of cement composites reinforced with two types of polypropylene fibrillated networks. Three storage conditions have been used —natural weathering storage inside in laboratory air, and under water storage. Some composites have been precracked before exposure and others left uncracked before testing. The parameters measured included the elastic modulus and cracking stress of the matrix, complete tensile stress-strain curves and crack distribution in the composite, and the effects of the different weathering conditions on the tensile strength, strain to failure and bond strength of the polypropylene reinforcement.

Multiple cracking in aligned polypropylene fibre reinforced cement composites

Multiple cracking in aligned polypropylene fibre reinforced cement composites

Multiple cracking in aligned polypropylene fibre reinforced cement composites

Multiple cracking has been shown to occur in hardened cement paste reinforced with aligned polypropylene fibres of elastic modulus considerably lower than that of the cement paste. The effect of fibre volume fraction on the distribution of matrix cracks has been studied and good agreement found with existing theory. Factors which enable fibre/matrix contact to be maintained during the multiple cracking process, despite the unfavourable Poisson's ratio contraction of polypropylene have been discussed. These include the lateral displacement of one surface of a crack relative to the other and also the lateral displacement of matrix material next to the crack surface relative to the fibre array. This latter mechanism is shown to apply to other aligned composites and calculations based on a simple theory predict that multiple cracking should occur in all composites provided that a critical size is exceeded.