Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : polypropylene fibers

Effect of Polypropylene Fibers on Thermal and Some Mechanical Properties of No-fines Concrete

B. H. Amanah; O. A. Eedan; B. S. Al-Shathr

Engineering and Technology Journal, 2017, Volume 35, Issue 1A, Pages 76-82
DOI: 10.30684/etj.2017.127313

This research aims to find the optimum percentage of polypropylene fibers that can be added to no-fines concrete. The fibers added to the (1:5, 1:6, and 1:7 mix proportions) concrete with volumetric percentages of (0.1, 0.2, 0.3, 0.4, and 0.5%), together with suitable amounts of superplasticizer to keep the flow percentage at (65-75%) using constant w/c ratio of 0.4. The results indicated that the optimum volumetric percentage of the added polypropylene fibers is 0.3% which needs small amount of superplasticizer of 0.5% by cement weight, to keep its flow equivalent to the reference mix. This percentage of fibers cause an increase in compressive strength, splitting tensile strength, and modulus of rupture of 22.5, 56.1, and 67.8% respectively when using 1:5 and 1:6 of concrete mixture. But this percentage decrease when using concrete mix proportion of 1:7 to be 8.8, 23.8, and 24% respectively. Also, results indicated that concrete density and thermal conductivity didn’t affect significantly by fibers addition.

Effect of Steel Fibers, Polypropylene Fibers and/ or Nanosilica on Mechanical Properties of Self-Consolidating Concrete

Iqbal N. Gorgis; Maan S. Hassan; Rana T. Abdulkareem

Engineering and Technology Journal, 2016, Volume 34, Issue 3, Pages 527-538

This research concerned studying the combined effect of using nano-silica and/ or hybrid fibers on key mechanical properties of self-consolidating concrete SCC. A comprehensive experimental work has been carried out, using steel fiber (SF) with volume fraction (0, 0.5% and 1.5%), polypropylene fiber (PPF) (0%, 0.05% and 0.15%) and SiO2 nanoparticles (0%, 2% and 4%) by weight of powdered material (silica fume- Sf ) with constant w/c ratio (0.48) to produce eleven different mixtures and tested at different ages (7, 28 and 90 days).
Results showed that adding fibers adversely affect SCC workability and thus more dosage of super plasticizer (SP) should be added to stay within the standard limits. comparable to conventional concretes, the presence of steel fibers with SCC provide slight increase in compressive strength at 28 days, (up to 11%), while significant enhancement in tensile properties were observed (up to 24% and 32% for splitting and flexural strength respectively). Polypropylene or hybrid fibers however, provide lower enhancement compared with steel fibers. In contrast, implementation of nanosilica leads to significant improvement in concrete strengths particularly at 4% dosage. Combined effect of 4% nanosilica and 1.5% of steel fibers provide the superior hardening effect on the flexural performance compared with softening effect provided by other added dosages. Scanning Electron Micrograph (SEM) images confirm the matrix densification effect due to nanosilica adding. Flexural strength of SCCs without nanosilica was generally higher than splitting testing results. This fact does not change even with the presence of nanosilica and/ or fibers.

Mechanical Properties of High Performance Fiber Reinforced Concrete

Wasan Ismail Khalil; Ikbal Naeem Gorgis; Zeinab Raad Mahdi

Engineering and Technology Journal, 2013, Volume 31, Issue 7, Pages 1365-1387

An experimental work was carried out to produce high performance concrete (HPC) using superplasticizer and silica fume reinforced with fiber. The variables studied were fibers type (steel fibers and polypropylene fibers), aspect ratio of steel fibers (60 and 100) and fiber volume fraction (0.0%, 0.5%, and 0.75%). The effect of fibers on the mechanical properties (compressive strength, splitting tensile and flexural strength, static modulus of elasticity, toughness, and resilience) of normal strength and high performance concrete was also studied. The results show that the optimum dosage of silica fume is 5% as addition by weight of cement with superplasticizer dosage 2 liter/100kg of cement. This dosage of silica fume improves the compressive strength of concrete by about 25% relative to concrete mix without silica fume. The addition of steel fibers causes a slight increase in compressive strength of HPC as fiber volume fraction increases, while the compressive strength decreases as fiber aspect ratio increases. Both splitting tensile and flexural strengths show a significant increase as the fiber volume fraction and aspect ratio increases. The percentage increase in compressive, splitting tensile and flexural strengths for HPC with steel fiber volume fraction 0.75% and aspect ratio 100 at age 60 days is about 9%, 75%, 64%, while for HPC containing polypropylene fiber with volume fraction 0.5% is about 8.5%, 2%, 0% respectively relative to non fibrous HPC.