Combination Of Polypropylene Fibers Research Articles

Hybrid Fiber Influence on the Crack Permeability of Cracked Concrete Exposed to Freeze-Thaw Cycles.

This paper describes hybrid fiber's influence on the crack permeability of cracked concrete exposed to freeze-thaw cycles. A permeability setup and a laser-scanning setup have been designed to measure the crack permeability and the fractured surface roughness of cracked hybrid fiber-reinforced concrete, containing polypropylene fiber and steel fiber, under a splitting tensile load. The results show that, when the effective crack width of the specimens is less than 25 μm, the rough crack surface significantly reduces the concrete's crack permeability. As the crack width increases, the effect of the concrete crack surface on crack permeability gradually decreases, and the crack permeability of the concrete is closer to the Poiseuille flow model. The permeability parameter α derived from the Poiseuille flow model is effective for assessing the crack permeability of concrete. Compared to the modified factor ξ of crack permeability, the permeability parameter α can effectively evaluate and quantify the development trend of crack permeability within a certain range of crack widths. The permeability parameter α of SF20PP2.3, subjected to the same freeze-thaw cycles, decreases by 16.3-94.8% compared to PP4.6 and SF40, and SF20PP2.3 demonstrates a positive synergistic effect on the crack impermeability of cracked concrete. The crack impermeability of SF40PP2.3, subjected to the same freeze-thaw cycles, lies between that of PP6.9 and SF60. The roughness of crack surface (X) and the crack permeability (Y) are highly correlated and follow an exponential curve (Y = 1.0415 × 107·e-6.025·X) in concrete. This demonstrates that hybrid fibers enhance crack impermeability by increasing the crack surface roughness. Furthermore, the combination of polypropylene fiber and steel fiber effectively promotes the formation of micro-cracks and facilitates the propagation of multiple cracks in the concrete matrix. This combination increases the head loss of water flow through the concrete and decreases the crack permeability.

The Effect of Polypropylene Fiber and Steel Fiber on Geopolymer Concrete

One of the environmentally friendly concrete as an alternative to cement concrete in the future is geopolymer concrete which used a cement substitute in the form of fly ash. To prevent premature cracking of the concrete, this study added fiber types such as polypropylene fiber, and steel fiber (dramix), this experiment with 3 variables namely the addition of polypropylene fiber by 0%, 0.40%, 0.80%, 1.2%, steel fiber of 0.25%, 0.50%, 0.75%, 1.00%, as well as a combination of polypropylene fiber and steel fiber (0.4%P;0.50%D), (0.8%P;0.75%D), (1.2%P;1.00%D) of the weight of the concrete. In this study, using a beam specimen measuring 10x10x50 cm, for each percentage of fiber usage there are 2 beam trials. Geopolymer concrete in this study uses a ratio of NaOH and Na2SiO3 is 2:1 and a constant concentration of 10 Molar, to test the Flexural Strength Test of Concrete at the age of 28 days of concrete. The results of the highest average flexural strength of geopolymer concrete without fiber σl = 78.77 kg/cm2, using polypropylene 0.80% σl =50.50 kg/cm2, and 0.25% steel fiber σl =68.87 kg/cm2, the combination of both fibers (P0.4%; D0.25%) σl =65.34 kg/cm2. These results do not produce good workability, thus affecting the decrease in flexural strength. By increasing the ratio A = 0.35 to 0.45, the geopolymer concrete mix produces better workability with the highest average flexural strength of geopolymer concrete with polypropylene fiber 0.8% σl = 80.107 kg/cm2.

Study on the engineering properties of concrete made of poypropylene fiber and combination of silico manganese slag

As the concrete is high in compressive and bad in tensile, which develops micro cracks in under loading which is major disadvantage. It is the rapid propagation of these micro cracks under applied stress that is responsible for the low Tensile strength of the material. Hence fibers are added to concrete to overcome these disadvantages. The addition of fibers in the matrix has many important effects. The tests show that mixed use of polypropylene fibers and combination polypropylene and Silico manganese slag give good results in terms of improving structural characteristics of the concrete material developed. In all samples, the surface cracking was decreased significantly by adding suitable fibers in terms of sort, diameter and length. The concrete mostly used in construction materials, but it is economically high. In this project we will find the low cost and high strength by adding of combination polypropylene and Silico manganese slag. To improve tensile strength, compressive strength and flexural strength by adding polypropylene fiber 0 %, 0.5 %, 1 %, 1.5 %, 2 % by the volume of cement and with variation of silico manganese slag of 0 %, 10 %, 20 %, 30 % and 40 % by the volume of coarse aggregate. And it compares to the normal concrete by using M30 grade concrete. The tests show that mixed with polypropylene fibers and combination of polypropylene fiber and Silico manganese slag gives good results in terms of improving structural character of concrete developed. In project, silico manganese slag of size 20 mm and polypropylene fiber size 0.045 mm diameter and 6 mm length are used.

Influence on compressive and tensile strength properties of fiber-reinforced concrete using polypropylene, jute, and coir fiber

Abstract This research work is related to the use of environment friendly materials like fibers of coir, polypropylene and jute in concrete. An economical reinforced concrete is produced by reducing the diameter of steel bar by using fiber ropes. We have examined the compressive and flexural strength of fiber-reinforced concrete. In this study, concrete mix is prepared by using coir fibers. Although instead of using only conventional steel bars, reinforced concrete behavior was investigated with the combination of polypropylene fiber and jute fiber ropes along with steel bars for a constant water binder ratio. These fiber ropes are wound around steel bar with the help of Zepoxy 300 for proper bonding of fiber ropes and steel bar. The results demonstrate that properties of concrete are enhanced by using fibers. Fiber ropes with steel bar in coir concrete increased the flexural strength and compressive strength by 6 and 7%, respectively. Furthermore, it is observed that the addition of fibers in concrete changes the cracking pattern of reinforced concrete beams.

Durability and thermal properties of prepacked aggregate concrete reinforced with waste polypropylene fibers

The prepacked aggregates fiber-reinforced concrete (PAFRC) is an innovative type of concrete composites that recently has gained popularity and pulled the attention of researchers worldwide. The PAFRC components can be manufactured by initially placing the mixture of coarse aggregates with various sizes and shapes and short fibers in the designed molds and then grouted with an especially ready mix mortar. Although prepacked aggregate concrete (PAC) or two-stage concretes have been used widely as construction materials, long-term performance, particularly in aggressive environments, have not been studied. Therefore, the current study investigated the long-term strength properties, resistance against acid and sulfate environments, as well as thermal properties. Two methods of grouting were used, namely, gravity and pumping. For each method, a total of six mixes comprising 30 mm length waste polypropylene (PP) fibers at dosages of 0–1.25% was prepared. The outcomes of the study revealed that the PAFRC specimens obtained a remarkable improvement in the long-term strength values. The findings expose that the rates of sulfate and acid attacks, in terms of mass and strength losses, were controlled significantly by adding PP fibers and POFA into PAFRC specimens. The combination of PP fibers and POFA, which provides a denser microstructure, resulted in the lower depth of carbonation and better performance of PAFRC specimens to delay the time of heat transfer to the middle part of concrete.

Experimental investigation on the flexural behavior of steel-polypropylene hybrid fiber reinforced concrete

This paper presents an experimental study on the flexural behavior of steel-polypropylene hybrid fiber reinforced concrete (HFRC) using four-point bending tests on 51 samples. Three types of steel fibers, i.e., straight, hooked-end and corrugated fiber, and a type of monofilament polypropylene fiber are considered. The flexural behavior in terms of load-deflection curves, load and deflection characteristics, toughness, cracking properties as well as the synergetic effect of hybrid fibers is studied. The results show that synergetic effect is observed for all the three types of steel fiber with the combination of polypropylene fiber on improving the flexural behavior of HFRC. Specimens with hooked-end fibers show the best flexural performance. However, the combination of straight steel and polypropylene fibers presents the most obvious synergy. Moreover, an increase in volume fractions of both steel and polypropylene fibers leads to an increase in the compressive, splitting tensile and flexural strengths of concrete. The post-peak ductility of concrete is improved and the strength degradation is alleviated with increasing fiber volume fraction and steel fiber aspect ratio. In addition, specimens with corrugated and hooked-end fibers exhibit a better failure behavior than specimens with straight fibers, with multiply micro-cracks induced by mechanical interlocks of deformed steel fibers observed at the main cracks. Finally, based on a comprehensive fiber reinforcing index, analytical equations for flexural loads, deflections, and toughness of HFRC are developed with varying fiber parameters taken into consideration.

Precast tunnel segments reinforced by macro-synthetic fibers

The use of fiber reinforced concrete in tunnel linings, with or without conventional rebars, has increased in the two last decades, especially with regard to precast tunnel segmental linings. In addition, there is a general growing interest in the scientific community on macro-synthetic fibers for use in underground structures.Within this framework, the present study investigates the possibility of using polypropylene (PP) fiber reinforcement in hydraulic precast tunnel segments by means of an experimental program on six full-scale segments of Monte Lirio hydraulic tunnel (Panama). Three different reinforcement solutions were studied both under flexure and point load test: typical conventional reinforcement generally adopted in practice (reference samples, RC); PP fibers only (PFRC specimens); combination of PP fibers and conventional reinforcement (hybrid solution, RC+PFRC segments). Based on the loading configurations considered, experimental results showed that PP fibers (with or without reinforcing bars, depending on loading conditions) represent an efficient reinforcement for hydraulic precast tunnel segments. PP fibers can be used as flexural, splitting and minimum shear reinforcement, while concerning the spalling reinforcement, only PP fiber reinforcement could be used even if the combination with conventional reinforcement (hybrid solution) guarantees a better control of spalling cracks for high load levels.

Problematic Soft Soil Improvement with Both Polypropylene Fiber and Polyvinyl Acetate Resin

Several methods are used to improve mechanical properties of loose soils including rewetting, soil replacement, compaction control, chemical additives, moisture control, thermal methods, and more recently, discrete fibers. All the methods are applied to soft soil to increase load bearing capacity and to improve other properties such as prevention of erosion and dust generation. In the present study, a new method of soil improvement using both discrete polypropylene (PP) fibers and polyvinyl acetate (PVAc) is introduced. The method is applied to improve load bearing capacity of a problematic sandy soil in both dry and saturated states. Based on the results from CBR tests on various specimens, it has been revealed that the combination of PP fiber and PVAc resin with weight percentages of 0.1 and 0.6 %, respectively, had the optimum effect in increasing the CBR value in both saturated and dry soil specimens. It should be mentioned that this method has caused a great increase in the CBR value in the saturated soil.