Incorporating Polypropylene Fibers Research Articles

Highly nonlinear mathematical regression for polypropylene material strength prognostication

Concrete features high fragility, moderate bending strength, and endurance. Strain energy in the form of mechanical properties of polypropylene such as compressive strength, flexural strength, and split tensile strength are correlated via mathematical algebraic functions. Polynomial function, Exponential function , Fourier function , Gaussian function, the sumofthesinefunction, and Power function are used for correlation. Furthermore, fifteen customs equations are considered in this work. The application of polypropylene fibers to concrete could strengthen such unsatisfactory output. The polypropylene fiber reinforced cement concrete matrix has expanded dramatically due to its operational superiority. The paper examines concrete statistical properties by incorporating polypropylene fibers as reinforcing material. Seven fiberconcrete combinations with a limit of 0%, 0.2%, 0.35%, 0.5%, 0.75%, 1%, and 1.5% polypropylene fiber were prepared on a volume basis. Single w/c ratio provided 0.4 for all concrete compositions. The results indicated a considerable change in the mechanical characteristics of the concrete. The experimental results found the mechanical properties of the concrete increase up to 0.5 % of the polypropylene content in the concrete. Compressive strength, split tensile strength, and flexural strength of the polypropylene concrete are increased by 17 %, 15.58%, and 7.53%, respectively, compared to conventional concrete. Regression coefficients were calculated for the best match in various linear and nonlinear functions. The numerical comparisons of mechanical strengths in linear and nonlinear regression determination coefficients revealed a significant relationship between strengths. Since the formal association between compressive and flexural strength of concrete, the compressive strength is about 8–11 times the flexural strength. The equation predicted values were within the required range, a technical possibility with a constant geometry of the polypropylene fiber presented for the strength of fiber-reinforced concrete. The suggested model and the experimental findings are in moderate correlation.

Development of 3D Printable Cementitious Composites with the Incorporation of Polypropylene Fibers.

Similar to conventional cast concrete, printable materials require reinforcement to counteract their low tensile strength. However, as traditional reinforcement strategies are not commonly used in 3D print applications, fiber reinforcement can serve as an alternative. This study aims to assess the influence of different polypropylene fiber lengths (3 and 6 mm, denoted as M3 and M6, respectively) and dosages (0.1 and 0.3% volume fraction) on the workability, pore structure, mechanical and shrinkage behavior of 3D printable cementitious materials. Fresh state observations revealed that the addition of a higher fiber volume decreased the workability of the material, irrespective of the fiber length as a result of the lower water film thickness (WFT). In hardened state, a marginal increase in total porosity could be observed when adding fibers to the mix composition. In addition, the flexural strength was found to increase with the addition of fibers, while no significant difference was observed in compressive strength. The increase in flexural strength was more pronounced in the case of longer-sized M6 fibers. Finally, the total drying shrinkage behavior was evaluated using mold-cast prisms. The addition of M6 fibers showed no beneficial effect in reducing total free shrinkage, while a reduction in total free shrinkage was observed when using M3 fibers.

Characterization of the Physical and Mechanical Properties of Concrete with Polypropylene Fibers for Solid Mezzanine Slabs of Multi-Family Homes

The significant increase in the construction of buildings has led to the appearance of different phenomena that affect the elements that make it up. Due to their large area, in contact with the surface, solid slabs are the most vulnerable to these effects. The appearance of cracks at an early age is one of the most recurrent problems in concrete slabs, which is why it is important to counteract the presence of cracks to improve their mechanical properties to obtain buildings with greater durability. For this, the incorporation of polypropylene fibers has become one of the best alternatives to mitigate the appearance of cracks. In the present investigation, two concrete mixtures reinforced with polypropylene fibers of two lengths will be evaluated and tested for slump, plastic shrinkage, compressive strength and residual flexural strength.

Mechanical Properties of Mortar Using Polypropylene Fibers

In the present paper the behavior of mortar reinforced with polypropylene fibers was studied. Different percentages of polypropylene fibers such as 0, 0.2, 0.4, 0.6 and 0.8% as volumetric fractions were used. Different properties which are flowability, density, compressive strength, flexural strength and splitting tensile strength were evaluated for all mix combinations. The experimental results indicated that a reduction in flowability was obtained with increased polypropylene fibers content. Besides, it can be concluded that the incorporation of polypropylene fiber may significantly reduce the density of mortar. The use of low volume fraction of polypropylene fiber improves the mechanical properties of HPM. Thus, the use of 0.2% of such fiber increases compressive strength by about (4-10%), at various ages.

Mechanical properties and permeability of fiber-reinforced concrete with recycled aggregate made from waste clay brick

The use of crushed brick as coarse aggregates in concrete is of special significance for the protection of natural aggregate sources and the reduction of waste and waste storage. The objective of this experimental work was to study the application of fibers on fresh and hardened properties of concrete with recycled aggregates made from crushed clay bricks. For this purpose, a comparative study was performed on the mechanical and durability properties of fiber-reinforced concrete made with crushed brick as coarse aggregates and with natural aggregates. The effect of type and content of fibers on these properties is presented and discussed. Results show that the workability of fiber-reinforced recycled concrete was close to that of ordinary concrete. Compressive and splitting tensile strength of recycled concrete are significantly affected by fibers. Fiber can improve water impermeability. The water absorption was almost halved when PP fiber content is 0.6 kg/m3. Fibers will not significantly affect its gas permeability. The incorporation of polypropylene fiber also densifies the microstructure of recycled concrete.

Effect of polypropylene fibers on high strength mortar subjected to elevated temperature

This study focuses on the thermo-mechanical properties of mortar in the retrofitting cover of additional reinforcement for existing concrete structures. In addition, the residual mechanical properties of high strength mortar incorporating polypropylene fibers subjected to the effect of fiber length and the elevated temperature were investigated. Several experiments were conducted to determine the optimum mixture proportions of high strength mortar incorporating polypropylene fibers which had a slump-flow of 25–30 cm, compressive strength of 50 MPa or higher, and flexural strength of 4–8 MPa. Subsequently, an experiment was conducted by using high-strength mortar-blended polypropylene fibers with a length of 2 cm, and the ratio of fiber length to the diameter of cylinder mortar-specimens was 0.4. The experimental parameters were the weight volume of fibers (0 %, 0.5 %, 1 %, and 2%) and the heating temperature (100, 200 and 300 °C). The effect of the mixing parameters, including polypropylene length on compressive strength, slump-flow and the flexural strength of mortar were discussed. It is evident that fiber in the mortar cover influenced the initial and residual mechanical properties, such as elasticity, compressive strength, and Poisson’s ratio, of the mortar.

Effect of thermal damage on mechanical behavior and transport properties of self-compacting concrete incorporating polypropylene fibers

Explosive spalling of cementitious composites when it is heated from surface is considered to be the most dangerous effect of damage of concrete structures subjected to fire attack, especially when it occurs in restricted areas such as underground tunnels. The main objective of the study presented in this paper is to investigate the influence of high temperature on mechanical behavior, pore size distribution and transport properties of self-compacting concrete reinforced with polypropylene fibers (PPF). The experiment investigation was carried out using two mixtures with a constant water-to-binder ratio (w/b) of 0.37. Two SCCs mixtures were manufactured using an industrial cements according to European standard EN 197 1: CEM I 52.5 N (Portland cement), the difference between the mixtures is the presence of PPF. The amount of fibers used was fixed in 2 kg/m3, as recommends Eurocode 2 for high performance concrete to avoid explosive spalling. The specimens were subjected to various heating-cooling cycles from the room temperature 20 °C to 200 °C, 300 °C, 400 °C and 500 °C. The chloride resistance of the two SCC produced with the different mixtures in damaged and undamaged state are measured using a chloride migration test accelerated by an external applied electrical field. Intrinsic permeability is measured using the nitrogen gas. Klinkenberg approach is used for the determination of the intrinsic permeability. Torrent permeability measurement method was applied in this article, and a correlation was obtained between measure of intrinsic permeability and the Torrent permeability measurement. Finally, a relationship between thermal damage indicators and the increase in permeability and migration coefficients is also obtained.

Evaluation of mechanical and durability properties of fiber-reinforced lightweight geopolymer composites based on rice husk ash and nano-alumina

In the current study, the physical and mechanical properties of polypropylene fiber-reinforced lightweight geopolymer concretes are assessed. Geopolymer synthesis consists of rice husk ash (RHA) and nano-Al2O3 (NA) as solid precursors and 10 M sodium hydroxide (SH) and sodium silicate (SS) with a ratio of SS/SH = 2.5 as alkaline solution. NA amount is 20% of total volume of the binder for all mixtures. Scoria particles are used as lightweight aggregates (LWA) with replacement ratio of 0, 10 and 20% by volume of the total aggregates. Polypropylene (PP) fibers is added to the mixture with the amount of 0, 0.5 and 1% by the volume of the binder. Compressive and flexural strength, density, water absorption and rapid chloride permeability test (RCPT) were evaluated. Results indicated that PP fibers improves the mechanical properties (especially flexural strength) while incorporation of LWA reduced the compressive and flexural strength slightly. Water absorption of geopolymer samples decreased by the incorporation of PP fibers which can compensate significantly the negative impact of LWA replacement. Replacement of 10% LWA does not have significant impact on water absorption and chloride permeability of composites; however, 20% replacement reduced durability. Introduced lightweight geopolymer concrete would be suitable for structural applications due to its relatively low density, high compressive strength and good flexural strength, which is improved by adding PP fibers.

Experimental Investigation on Damage Behavior of Polypropylene Fiber Reinforced Concrete under Compression

This paper presents an experimental investigation on the stress–strain behavior and the damage mechanism of polypropylene fiber reinforced concrete (PFRC) under monotonic and cyclic compression. Fifty-four specimens for different fiber volume fractions and aspect ratios were tested. Acoustic emission (AE) technique was used to monitor the damage progression. The damage mechanism of concrete was analyzed based on the AE parametric analysis. The results show that the incorporation of polypropylene fiber (PF) has a positive effect on the monotonic and cyclic behaviors of concrete, especially for the post-cracking branch. The toughness and ultimate strain are enhanced and the performance degradation in terms of elastic stiffness and strength is alleviated by the addition of PF. However, PF has little influences on the plastic strain, and the damage process of concrete is mainly driven by the envelope strain. The effect of fiber volume fraction on the cyclic behavior of concrete shows more pronounced than that of aspect ratio. In addition, it is found from AE results that the damage, closely related to AE events, has a quick evolution just after the peak stress, with the AE hits having a concentrated release. The total amount of AE hits increases with increasing fiber volume fraction due to fiber pullout and sliding, while the concrete with fiber aspect ratio of 280 reaches the largest amount. Meanwhile, as substantiated by AE, the failure of PFRC shows an obvious shear mode, with shear cracks dominating the damage progression. Finally, a damage elasto-plastic model is developed to predict the monotonic and cyclic responses of PFRC and the prediction yields a fairly close estimation with experimental results.

Computational Analysis on Flexural Behavior of Precast Aerated Concrete Panel Incorporating Polypropylene Fiber

Precast system has great advantages in terms of its speed of construction, strength and durability. In this research, Precast Lightweight Aerated Concrete Panel, PACP, incorporating polypropylene fibers were utilized and tested to analyze its structural behavior under flexural load. Finite element analysis (FEA) using LUSAS software was utilized to simulate the PACP models under flexure load adopting nonlinear and transient analysis. The dimension of PACP panel was 200mm thickness, 500mm breadth, 1400 mm length. The FEA results were com-pared to theoretical results in terms of the panel’s ultimate load. Different thicknesses and reinforcement diameters were utilized in the FEM simulations to determine the optimum values for both parameters which confirm the stability of the panel. The outcomes demonstrated that 300 mm thickness is the optimum thickness while 12 mm diameter was the optimum size of reinforcement in the PACP panel.

Damage processes of polypropylene fiber reinforced mortar in different fiber content revealed by acoustic emission behavior

The performances of the cement-based materials can be improved by the incorporation of polypropylene fiber, but the damage processes become more complex with different fiber contents at the same time. The acoustic emission (AE) technology can achieve the global monitoring of internal damage in materials. The evolution process of failure mode and damage degree of polypropylene fiber reinforced mortar and concrete were analyzed by measuring the AE energy, RA value, AF value and b value. It was found that the cement matrix cracked on the initial stage, the cracks further developed on the medium stage and the fibers were pulled out on the last stage. The matrix cracked with minor injury cracks, but the fiber broke with serious damage cracks. The cumulative AE energy was proportional to the polypropylene fiber reinforced concrete and mortar’s ductility. The damage mode and damage degree can be judged by identifying the damage stage obtained by the analysis of the AF value.

Effect of natural pozzolana and polypropylene fibers on the performance of lime mortar for old buildings restoration

The main objective of this research is to elaborate a mortar based on lime (L), pozzolana (PZ) and polypropylene fibers (PP) to restore and renovate the stone constructions while maintaining their initial comfort. Unlike the new buildings, in rehabilitation, we have to deal with the existing ones. For this purpose, mortars samples from an old building, chosen as cases of study, were taken and chemically analyzed in order to reproduce their equivalent mortars. Three different mortars were made and studied. A lime based mortar (M1), lime-pozzolana based mortar (M2) and lime-pozzolana based mortar with polypropylene fibers (M3). In order to preserve the thermal comfort offered by the old building, the thermal conductivity and the mechanical proprieties were studied. The adhesion of each mortar was also tested on several support types (concrete, concrete block, brick and natural stone). Finally, the three studied mortars were applied on the facade of the chosen building. The results are satisfactory on both levels aesthetic and adhesion. The incorporation of polypropylene fibers was more promising regarding thermal comfort. Moreover, their use lightened the matrix and improved the tensile strength.

Synthesis of polypropylene fiber/high-calcium fly ash geopolymer with outdoor heat exposure

Solar energy is an important source of renewable and sustainable energy. Thailand is near the equator and thus experiences hot weather throughout the year. The average maximum temperature is 35 °C and can reach 40 °C in the summer time. This outdoor heat exposure (OHE) was, therefore, used for the curing of a polypropylene (PP) fiber fiber-reinforced high-calcium fly ash geopolymer composite, in order to reduce energy consumption. Fly ash is an abundant solid waste generated from the coal-power generation process. In this research, a high-calcium fly ash was used as a source material for the geopolymer synthesis. PP fiber was also incorporated in the composites to improve tensile characteristics and control crack development. The results show that the incorporation of PP fiber in composites led to improved tensile strength, crack control, and resistance to acid solution. OHE could thus be used as an energy source for the heat curing of high-calcium fly ash PP-fiber geopolymers, resulting in a strong matrix.

Acetic Acid Role on Magnesia Hydration for Cement‐Free Refractory Castables

Different approaches to master magnesia hydration in refractory castables have been recently proposed. Among them, the use of hydrating agents can change the Mg(OH)2 crystals morphology and its distribution in the resultant microstructure, minimizing the drawbacks related to the reaction expansion. In this work, the hydrating effect of acetic acid in Al2O3–MgO cement‐free castable properties during curing, drying, and firing steps was evaluated by elastic modulus, thermogravimetric, apparent porosity, and SEM analyses. Based on the attained results, adding acetic acid resulted in hydroxide crystals with distinct morphology and flexibility leading to a better accommodation of Mg(OH)2 in the designed microstructure, which inhibited the samples' cracking during curing. In addition, the drying behavior of the evaluated compositions was further optimized by incorporating polypropylene fibers. Thus, this study highlights a novel perspective for fine MgO powders application, indicating that brucite morphology engineering may be a key aspect for the development of advanced Al2O3–MgO cement‐free refractory castables.

Properties of gypsum composites containing vermiculite and polypropylene fibers: Numerical and experimental results

We have added expanded vermiculite and polypropylene fibers with low thermal conductivity to lightweight gypsum. Thermal conductivity of the composites decreases on addition of vermiculite as pore-maker. Physical and mechanical properties of the composites are improved by incorporating polypropylene fibers. A nonlinear finite element model of a three point bending model and a design of experiments analysis have been developed to evaluate and optimize the additive concentrations and also to understand the effects provided by the additives on the mechanical strength. Statistical response surface method with three-level factorial was employed to evaluate the effect of addition of vermiculite and polypropylene fibers on gypsum composites. Our methodology can be applied to other nonlinear materials for property optimization.

Effect of nano-particles on durability of fiber-reinforced concrete pavement

In this study frost resistance and mechanical properties of fiber-reinforced concrete pavement containing nano-particles are studied. Nano-particles are employed to be as substitute of a portion of cement. For comparison the frost resistance and mechanical properties of plain concrete (control concrete), concrete containing nano-particles (without fibers) and concrete containing polypropylene fibers are also experimentally studied separately in this work. The specimens were subjected to cycles of freezing and thawing in water according to ASTM C666A. Experimental results show that using 5% nano-silica (by the weight of cementitious materials) improves the compressive strength and frost resistance of concrete as much as 30% and 83% respectively. Substitution 3% of cement by nano-alumina particles can improve compressive strength and frost durability of concrete as much as 8% and 81% respectively. Experimental results also show that polypropylene fibers can slightly affect the frost durability and compressive strength of concrete. As a general result it can be concluded that using nano-particles incorporating polypropylene fibers enhances frost resistance and compressive strength of concrete pavement because of that the permeability and porosity of concrete are reduced due to the use of nano-particles and also the tensile strength of concrete is enhanced due to the use of polypropylene fibers.

Performance and Mechanism Study on C50 Micro-Expansion Polypropylene Fiber Reinforced Anti-Cracking Pumping Concrete

Based on the construction application of C50 anti-cracking pumping concrete, the influence of the polypropylene fiber and expansive agent on the concrete was studied. The workability, mechanical property, drying shrinkage and crack resistance of the pumping concrete and their mechanisms were tested. The results indicated that the workability achieve the standard of pumping concrete through increasing the dosage of polycarboxylic superplasticizers. The incorporation of polypropylene fiber and expansive agents has little influence on the compressive strength and elastic modulus, but will significantly enhance split tensile strength and decrease the drying shrinkage and cracking.

The long-term compressive strength and durability properties of silica fume fiber-reinforced concrete

Abstract The long-term compressive strength and durability properties of concrete specimens produced by incorporating polypropylene fibers and silica fume were investigated. Silica fume, a cement replacement, was used at 8% (by weight of cement) and the volume fractions of the polypropylene fibers were 0%, 0.2%, 0.3% and 0.5%. Water-binder ratios were 0.46 and 0.36. The results indicate that the inclusion of fiber and particularly silica fume into the specimens led to an increased long-term compressive strength. Electrical resistance of the silica fume specimens improved remarkably, but decreased slightly due to the fiber inclusion. Water absorption of the fiber–silica fume specimens decreased exclusively compared to the reference samples. Inclusion of fiber and silica fume into the specimens had no considerable effect on the dynamic frequency results.

Enhancement on Mechanical Properties of Hybrid Concrete by Incorporating Fibers with Different Geometrical Dimensions

With numerical modeling in meso level, impaction of incorporating polypropylene fibers with two different geometry dimensions on flexural strength and toughness of hybrid fiber concrete has been studied in this paper. Mechanism of such hybrid fiber reinforcement has also been analyzed. The results show that hybrid of fibers with different geometric dimensions would bring about synergy, thus fiber enhancement effect could be demonstrated. Furthermore, the closer the incorporation ratio of these two kinds fibers are to each other, the more evident the enhancement will be produced. The most optimized hybrid ratio is in between 2:1 and 1:1.

Experimental Investigation on the Polypropylene Fiber Concrete Performance of Yellow River Canal Lining in the Middle Line of South-to-North Water Transfer Project

In order to meet the running needs of the first-stage construction in the middle line of South-to-North Water Transfer Project, the canal lining of both sides of Yellow River Tunnels Project need the use of mechanized equipment construction in order to improve the quality and efficiency of lining construction, there is a need to study the feasibility of the use of polypropylene fiber concrete instead of reinforced concrete in canal lining. This paper analyzes the effect of polypropylene fiber on concrete shrinkage and crack resistance. The results show that all three polypropylene fibers have properties of a low density and high elongation, the dispersivity test results show that dispersivity is better when stirring fiber A after a certain period of time. After the incorporation of polypropylene fibers, the concrete splitting tensile strength is significantly increased, altogether with ultimate tensile value and frost resistance. The incorporation of polypropylene fibers increases the tensile strength of concrete and improve the toughness of it. Compared with standard concrete, the early shrinkage of polypropylene fiber concrete is significantly lower, the incorporation of polypropylene fibers can take the place of steel mesh in concrete cracking, especially in the early control of concrete cracks, it can effectively prevent and suppress the cracks formation and development. This paper recommends the concrete proportioning parameters meeting the requirements of canal lining concrete technology and construction.