Polypropylene Fibers
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Author(s):  
Behzad Isazadeh-Khiav ◽  
Tohid Akhlaghi ◽  
Masoud Hajialilue-Bonab

The main goal of this research is to study the failure behavior of cement-fiber-treated sand under triaxial direct tension condition tests. Thus, a new loading system and triaxial cell was designed and built for tensile loading. Samples were prepared with content cement of 3 and 5% (dry wt.) of the sand, while two types of polypropylene fibers 0.024 m in length and 23 μm and 300 μm thick were added at 0.0% and 0.5% (dry wt.) of the sand and cement mixture. After a seven-day curing period, the samples were loaded under triaxial direct tension tests under confining pressures of 100, 200, and 300 kpa in drained conditions. Stress-strain behavior, changes in volume and energy absorbed by cement-fiber reinforced sand were measured and compared with the results of other studies. Adding fibers resulted in reduced peak deviatoric stress and increased residual deviatoric stresses of the cement-fiber reinforced sand, with changes from brittle to ductile behavior. The initial stiffness and stiffness at 50% maximum tensile stress of the samples is decreased with the addition of fibers and with an increase in fiber diameter, the reduction rate of this stiffness is more evident. The absorbed energy for fibers with a thickness of 23 μm is less than fibers with a thickness of 300 μm. The effect of adding fibers to strength parameters showed that the cohesion intercept decreases, while the internal friction angle increases.


Author(s):  
Mahmoud Saad ◽  
Vincent Sabathier ◽  
Anaclet Turatsinze ◽  
Sandrine Geoffroy

Throughout time, the use of lignocellulosic resources has been implemented in the development of building materials. Among these resources, natural fibers are used as mineral binders reinforcement due to their specific mechanical properties. This experimental investigation focused on effect of flax and hemp fiber reinforcement on the resistance of pozzolanic-based mortars to cracking due to restrained plastic shrinkage. Results were compared with polypropylene fiber reinforcement and with control mortar without fibers. The quantity of fibers added to the mortar mix were respectively 0.25% - 0.5% by mass of binder for polypropylene fibers and 0.5% - 1% by mass of binder for flax and hemp fibers. All fibers have a similar length of 12 mm. The cracking sensitivity was evaluated based on two different methods: the first consists in casting the mortar in a metal mold with stress risers whose criteria are inspired by the ASTM standards. The second consists in pouring the mortar on a brick support. In order to assess the effect of fibers on cracking due to restrained plastic shrinkage, the number of cracks, total crack area and maximum crack width within the first 6 hours after casting were determined using digital image correlation (DIC). Results showed that the flax and hemp fibers were more effective in controlling restrained plastic shrinkage cracking compared to polypropylene fibers. With a natural fiber of 1% by mass of binder, maximum crack width was reduced by at least 70% relative to control mortar based specimens. Natural fibers show great ability to propensity for cracking due to restrained plastic shrinkage; so that, they could be an alternative and ecological solution for polypropylene fibers.


Author(s):  
Mahmoud Saad ◽  
Vincent Sabathier ◽  
Anaclet Turatsinze

Given their specific properties, their natural and renewable sources and their low environmental impact in production, natural fibers offer an opportunity for the development of eco-friendly cement-based composites. The main objective of this experimental work is to evaluate the resistance to the impact load of mortars incorporating natural fibers or polypropylene fibers at 28 days. The assessment was carried out according to an experimental protocol developed in our laboratory. The method consists in dropping a metallic ball on a square shaped specimen of 30x30x2 cm3 to determine the energy supported by each sample. For each specimen, the number of blows required for the first crack initiation and for the total collapse of specimen are detected using a device allowing to measure the speed of ultrasonic waves. The device was fixed on the specimen itself. In order to fulfill the mechanical identity card of the composites, flexural and compression tests were also carried out at 28 days. In this experimental protocol, the pozzolanic binder was considered with different fiber percentages of polypropylene (0.25% and 0.5% by mass of binder) and of natural fibers (0.5% and 1% by mass of binder). All fibers have a length of 12 mm. Results show that natural fiber reinforcement could be considered as an ecological alternative to polypropylene fiber one to improve the resistance of mortars to impact loads.


2022 ◽  
pp. 52111
Author(s):  
Vadim V. Zefirov ◽  
Victor E. Sizov ◽  
Stanislav V. Dvoryak ◽  
Alexander A. Gulin ◽  
Vladimir G. Sergeyev ◽  
...  

2021 ◽  
Vol 4 (4) ◽  
pp. 227-238
Author(s):  
Alper Karadis ◽  
Kabil Cetin ◽  
Taha Yasin Altıok ◽  
Ali Demir

Glass fiber reinforced polymer (GFRP) composites have been frequently used in engineering applications in recent years. GFRP composites produced by using glass fiber and epoxy resin have significant advantages such as high strength, lightness, and resistance against corrosion. However, GFRP composites exhibit a more brittle behavior than steel bars. This study aims to investigate both the experimental and numerical bending behavior of slabs with GFRP bars, steel bars, and polypropylene fiber. Within the scope of experimental studies, 5 slabs were built. Two slabs called SS-1 and SS-2 have only steel bars. Two slabs called GFRPS-1 and GFRPS-2 have only GFRP composite bars. A slab called GFRPS-F has both GFRP composite bars and polypropylene fibers. Polypropylene fibers are added to fresh concrete to improve the slab’s ductility. Three-point bending tests have been carried out on the slabs. All slabs are subjected to monotonic increasing distributed loading until collapse. As a result of tests, GFRPS slabs have carried %53 higher load than SS slabs. However, the SS slabs have exhibited a more ductile behavior compared to the GFRPS slabs. GFRPS slabs have more and larger crack width than other slabs. The addition of 5% polypropylene fiber by volume to concrete has a significant contributed to ductility and tensile behavior of slab. The average displacement value of GFRPS-F slab is 22.3% larger than GFRPS slab. GFRPS-F slab has better energy consumption capacity than other slabs. The energy consumption capacity of GFRPS-F slab is 1.34 and 1.38 times that of SS and GFRPS slabs, respectively. The number of cracks in GFRPS-F slab is fewer than GFRPS slabs. The fibers have contributed to the serviceability of the GFRPS slabs by limiting the displacement and the crack width. GFRPS-F exhibits elastoplastic behavior and almost returns to its first position when the loading is stopped. In addition, experimental results are verified with numerical results obtained by using Abaqus software. Finally, it is concluded that GFRP composite bars can be safely used in field concretes, concrete roads, prefabricated panel walls, and slabs.


Author(s):  
Minakshi Uchibagle ◽  
B Ram Rathan Lal

Controlled low-strength material (CLSM) is a self-levelling cementitious material. It is not concrete nor soil-cement, however, it possesses properties similar to both. CLSM is widely used as a replacement for soil-cement material in many geotechnical applications such as structural backfill, pipeline beddings, void fill, pavement bases and bridge approaches. This paper study potential possibility of polypropylene fiber in CLSM. Harden and fresh properties compressive strength , flowability and density for the proposed CLSM were investigated. This CLSM mix design with different percentage of polypropylene fiber and pond ash, cement and water. EPS beats and polypropylene add 0 %, 0.5%, 1.0% and 1.5% of total weight is added in CLSM MIx. Results show that the CLSM incorporating EPS beats and polypropylene satisfies compressive strength requirement as per the requirements of ACI committee 229. polypropylene decreases the flowability of CLSM mix and at the same tine by adding EPS beats the density of CLSM mix are reduce which become lightweight CLSM mix. from this it can conclude that polypropylene fibers is less effective in CLSM mix and EPS beats make CLSM mix lightweight which create lightweight CLSM mix applicable for filling application.


Author(s):  
Xin Yang ◽  
Ninghui Liang ◽  
Yang Hu ◽  
Rui Feng

AbstractTo study the influence of polypropylene fibers with different thicknesses on concrete beams, inclined section shear tests of polypropylene fiber concrete beams were carried out. The cracking load, ultimate load, midspan deflection, reinforcement, and strain of polypropylene fiber concrete beams and conventional reinforced-concrete beams under shear were compared and analyzed. The load-bearing capacity of the rectangular beams was improved significantly by polypropylene fiber addition. Compared with conventional reinforced-concrete beams, the limit shear load of concrete beams with polypropylene fibers and multisize polypropylene concrete beams that were reinforced with three types of fibers increased by 8.67% and 17.07%, respectively. By mixing polypropylene fibers into concrete beams, the initial crack shear force of the beam was improved, the number of cracks was increased and the crack width was reduced, which can increase the beam ductility, inhibit crack formation and increase the strength. The computational formula of the shear ultimate bearing capacity of polypropylene fiber–concrete beams was revised according to composite material theory, and the calculated results were consistent with the test values.


2021 ◽  
Vol 7 (12) ◽  
pp. 2099-2108
Author(s):  
Qais J. Frayyeh ◽  
Mushtaq H. Kamil

Despite their drastically different chemical ingredients and interactions, geopolymer concrete exhibits many of the same features as ordinary concrete. Among these properties is drying shrinkage. As in normal concrete, dry shrinkage in geopolymer concrete may cause cracking if the geopolymer concrete is bound, which affects the integrity of the structure in the future. It's important to measure drying shrinkage as soon as possible because it's the cause of early age cracking, which happens when the concrete isn't very strong. The purpose of this study is to determine how to reduce the dry shrinkage value of geopolymer concrete by using different types of fibers. Three types of fibers were used to determine their effect on the dry shrinkage of geopolymer concrete when compared with a reference mixture without the fibers. Metakaolin was used as a binder for the concrete geopolymer. As for the fibers, steel, carbon and polypropylene fibers were used in proportions of (0, 0.5, and 1%). The results showed an improvement in dryness shrinkage when adding fibers in general, with a difference in values between the different types of fibers. Steel fibers had the lowest amount of dry shrinkage. The temperature had a direct influence on the decrease in the extent of the shrinking, since the samples handled at higher temperatures had less dryness to begin with. Doi: 10.28991/cej-2021-03091780 Full Text: PDF


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