Inclusion Of Polypropylene Fibers Research Articles

Identification of fracture parameters of fiber reinforced concrete beams made of various binders

Geopolymer concrete (GPC) is currently a hot research area. This work aims to study the fracture behavior of beam specimens with and without steel reinforcement and cast with different binders. Forty-eight notched-beams with dimensions of 100×150×1000 mm were used and tested in three-point bending loads. Different variables taken into consideration mainly, notch height (0, 50, 75 mm), reinforcement ratio (0%, 17%), replacement ratio of fly ash with cement (0%, 20%, 30%, 50%) in GPC, replacement ratio of cement with fly ash (0%, 50 %) in Portland cement concrete (PCC), polypropylene fibers content (0%, 0.5%, 0.75%). were studied. The load-deflection, and crack mouth opening displacement (CMOD) were considered as the characteristic responses at various stages of loading. Fracture Toughness (KIC), Fracture Energy (GF), Characteristic Length (Ɩch), Brittleness (B), J- Integral (JIC) were calculated to evaluate the fracture behavior of the beam specimens without reinforcement. Whereas, brittleness number (NP), dimensionless number (S), and the ratio of plastic moment / critical moment (MP/MF) were calculated to evaluate the fracture behavior of the beam specimens with reinforcement. The results revealed that, the GPCs exhibit similar behavior and fracture properties that those determined in PCCs. Hence, the inclusion of polypropylene fibers to different concrete mixtures noticeably enhanced their fracture properties, while the brittleness was reduced with the increase of the polypropylene fibers content.

Study of the effect adding the polypropylene fibers and chemical additives on the behavior of Ultra-High-Performance Concrete

Ultra-High-Performance Fiber-reinforced concrete (UHPFRC)is an improved best of types of concrete containing fibers randomly distributed inside it, and high resistance give. The mechanical properties of concrete have been developed namely, compressive, flexural, and tensile strength by adding the fibers, and some chemical additives (superplasticizers) to reduce the percentage of water, and to ensure suitable workability. Also, the fiber makes the concrete very durable, tougher, and lower permeability. This paper aims to enhance the concrete mechanical properties by adding polypropylene fibers in combination with superplasticizers as a partial cement replacement. Test results give a good improvement by using both polypropylene fibers and superplasticizers. The split tensile strength and the flexural strength are increased significantly from 14.1 to 18.3 MPa, and from 14.28 to 20.85 MPa, respectively. While concrete strength of compression increased from 124.05 MPa to 145.87 MPa due to the inclusion of polypropylene fibers and superplasticizers. This will be seen as the experimental results showed a big improvement within the residual mechanical properties of the UHPFRC which contain the fibers compared to concrete mixes without fibers.

Effect of polypropylene fiber inclusion in kaolin clay stabilized with lime and nano-zeolite considering temperatures of 20 and 40 °C

A laboratory study was carried out to evaluate the effect of lime, nano-zeolite, and polypropylene fibers on EC, pH, unconfined compressive strength (UCS), E50, Eu, and indirect tensile strength (ITS) of kaolin clay cured at the temperatures of 20 and 40 °C after various treatment times. Furthermore, X-ray diffractometer (XRD) and scanning electron microscopy (SEM) analyses were performed to assess the microstructure of the stabilized/reinforced samples. Based on the results, the replacement of lime with nano-zeolite has a beneficial effect on mechanical characteristics. The addition of nanoparticles up to 40% replacement had the best efficiency on the strength of the stabilized samples, particularly at the temperature of 40 °C. So that the samples containing 10% lime with 40% replacement of nano-zeolite after 28 days of curing at 20 and 40 °C showed a compressive strength of about 20 and 7 times compared to that of kaolin clay. Increasing the amount of lime also increases the peak strain energy (Eu) and secant modulus (E50). Moreover, the incorporation of fibers, despite the slight decrease in compressive strength, shows a great ability to increase tensile strength and strain of the samples and, consequently, increase the Eu. The results of the XRD and SEM tests showed that the inclusion of additives in the kaolin clay altered the soil structure and form the calcium silicate hydrate (CSH) gels during the pozzolanic reaction.

Abrasion of Reactive Powder Concrete under Direct Water Impact

An experimental program was directed in this study to evaluate the abrasion resistance of reactive powder concrete (RPC) under direct normal impact of water jet. Abrasion and compressive strength specimens were cast from six RPC mixtures using different single and hybrid distributions of 6 mm-length and 15 mm-length micros-steel fibers and 18 mm-length polypropylene fiber. Fixed mix proportions were used for the six RPC mixtures and with fixed total volumetric fiber content of 2.5%. In addition to the RPC mixtures, a normal concrete mixture was prepared for comparison purposes. All specimens were cured in the same conditions and tested at an age of 28 days. The test results showed that abrasion weight losses increase with time at rates that are independent of fiber type and fiber distribution. The results also showed that all RPC mixtures exhibited significantly lower abrasion losses than normal concrete. The lowest percentage abrasion weight losses were recorded for the mixture with pure 15 mm micro-steel, where after 12 testing hours, it was 0.41% of the total weight before testing. On the other hand, the mixture with pure 6 mm micro-steel fiber exhibited the highest percentage abrasion weight loss (0.98%) among the six RPC mixtures. Another conclusion is that the inclusion of polypropylene fiber to compose hybrid fiber distribution with micro-steel fiber led mostly to lower abrasion losses.

Mechanical properties and drying shrinkage of lightweight cementitious composite incorporating perlite microspheres and polypropylene fibers

This research focuses on the development of lightweight cementitious composite (LCC) with targeted densities, 800 kg/m3 and 1000 kg/m3 by incorporating perlite microspheres. The mechanical properties and the drying shrinkage of the LCC with 0.15%, 0.30% and 0.50% of polypropylene fibers were evaluated. It was found out that compressive strength achieved by LCC is in the range of 10.4–23.2 MPa and the specific strength achieved is up to 23.70 kPa/kgm−3 which is superior than most of lightweight concretes with similar density. Although the effect of polypropylene (PP) fibers on the compressive strength was minimal, the inclusion of low PP fibers dosage could improve the flexural strength of LCC up to 26.7%. The inclusion of PP fibers also showed positive effect in reducing the drying shrinkage strain of LCC. In overall, LCC with good mechanical properties and acceptable shrinkage was successfully developed.

Investigation of eco-friendly fiber-reinforced geopolymer composites incorporating recycled coarse aggregates

Structural-grade geopolymer concrete (GPC) containing metakaolin (MK) was assessed by partial inclusion of recycled coarse aggregate (RCA) to produce environmental-friendly composites. Polypropylene (PP) fiber was also used at different weight ratios. Mechanical and durability properties of GPCs were then evaluated. The impact of fiber and RCA on the microstructure of geopolymer paste and interfacial transition zone in different parts were evaluated. The results indicated no significant change on compressive strength by the inclusion of PP fiber. However, a remarkable improvement in flexural and splitting tensile strength and drying shrinkage was observed through the inclusion of PP fiber. Load–displacement graphs revealed that PP fiber increases the GPC fracture toughness and improves the maximum load capacity. Although the compressive strength of samples decreased by the RCA inclusion, the strengths achieved were still appropriate for structural applications. From microstructural point of view, it was found that fiber and geopolymer paste have a firm bound, which would contribute to constraining the propagation of potential cracks. It was indicated that the combination of 1% PP fiber and 20% RCA in MK-based GPC leads to an eco-friendly concrete mix with appropriate hardening properties that would contribute to the sustainability in the construction industry.

Effect of polypropylene fiber inclusion on the compressibility and consolidation characteristics of dredged marine soil

Dredged marine soil (DMS) is a geo-waste that was produced during maintenance dredging. It is unlikeable to the geotechnical engineer as the soil is weak and low in bearing capacity. However, the poor engineering properties of DMS can be improved by soil reinforcement. So far, there has been little quantitative analysis of high water content DMS in terms of compressibility and consolidation. Hence, this experimental study evaluates the effect of PP fiber on the compressibility and consolidation behaviors of DMS. Different water contents (ranging from 0.90 to 1.46 times the liquid limit of the soil), type of soil (ML and MH), and fiber contents (0–1.00% by dry weight of soil) were chosen as the experimental variables in this research. A series of one-dimensional consolidation tests by using conventional oedometer were conducted on the reinforced DMS to determine the compressibility and consolidation characteristics such as compression index (cc), coefficient of consolidation (cv), coefficient of volume compressibility (mv), and soil constraint modulus (D). From the study, in term of compressibility, DMS admixed with 0.5% of PP fiber has resulted in lower consolidation settlement and high stiffness than DMS with 1.0% of PP fiber. Hence, it is suggested that 0.5% of PP fiber in DMS is the optimum content. As for consolidation, the cv values are in the range of 0.05–0.5 and 0.5–10 m2/year, which classify the soil in the range of high plasticity clay and low-medium plasticity silt, respectively. Although the results show that the addition of PP fiber in DMS has improved the soil, however, it is not substantial. Therefore, it is recommended to use higher content of PP fiber or admixed the soil with a binding agent such as cement to enhance the weak and high water content of DMS.

Experimental Study on the Influence of Polypropylene Fiber on the Swelling Pressure Expansion Attributes of Silica Fume Stabilized Clayey Soil

Expansive soil shows dual swell–shrink which is not suitable for construction. Several mitigating techniques exist to counteract the problem promulgated by expansive clayey soils. This paper explored the potential mecho-chemical reinforcement of expansive clayey soil to mitigate the effect of upward swelling pressure and heave. The polypropylene fiber is randomly distributed in the soil for mechanical stabilization, and the industrial residual silica fume is used as a chemical stabilizer. The experimental analysis was made in three phases which involved tests on mechanically-reinforced expansive soil, using randomly distributed polypropylene fibers with different percentages (0.25%, 0.50%, and 1.00%), and which were 12 mm length. The second phase of experiments was carried out on chemical stabilized expansive soil with different percentages (2%, 4%, and 8%) of silica, and the next phase of the experiment focused on the combination of mecho-chemical stabilization of the expansive soil with different combinations of silica (i.e., 2%, 4%, and 8%) and polypropylene fibers (i.e., 0.25%, 0.50%, and 1.00%). Maximum dry density (MDD), optimum moisture content (OMC), liquid limit (LL), plastic limit (PL), plastic index (PI), grain size, and constant volume swelling pressure tests were performed on unreinforced and reinforced expansive soil, to investigate the effects of polypropylene fiber and silica fume on the engineering properties of expansive clayey soil. The experimental results illustrate that the inclusion of polypropylene fiber has a significant effect on the upward swelling pressure and expansion property of expansive soil. The reduction in the upward swelling pressure and expansion is a function of fiber content. These results also indicated that the use of silica fume caused a reduction in upward swelling potential, and its effect was considerably more than the influence of fiber.

Pervious concrete: study of dosage and polypropylene fibers addiction

Abstract The use of pervious concrete to minimize the effects caused by the impermeability of the soil as a result of increasing urbanization is an alternative that still requires further studies regarding its design and implementation. From this perspective, this paper presents a study of the characteristics of pervious concrete, including its tensile strength, compressive strength, flexural strength and the permeability coefficient, through the development of various mixtures to adjust the characteristics of the local aggregates. Eight mixtures were studied based on a reference mixture, five of which were related to the pervious concrete with the addition of finer aggregates than the reference mixture without these aggregates. Subsequently, three mixtures were studied with the inclusion of polypropylene fibers in order to analyze the effects of the addition of fibers on the properties of the pervious concrete. It is concluded that the presence of fibers changed the characteristics of the concrete, increasing its strengths while achieving a good permeability in its mixtures. An improvement in the flexural strength of the pervious concrete was observed, which is the main property to be considered for its use in pavements, without harming the permeability, which raises the possibility for its application.

Toughness, elasticity and physical properties for the evaluation of foamed concrete reinforced with hybrid fibers

This study has been undertaken to investigate the evaluation of Fiber-reinforced Foamed Concrete (FRFC) performance by the use of toughness and non-destructive tests. These tests cover the workability, density, static modulus of elasticity, toughness, ultrasonic pulse velocity and absorption tests. Different FRFC mixes using carbon fibers in the order of 0.5, 1 and 1.5% carbon fibers were used. Also, the combinations of carbon fibers (C) and polypropylene fibers (PP) as 1% C+ 0.5% PP, and 0.5% C+1% PP were prepared. Lastly, the inclusion of polypropylene fibers with the order of 1.5% PP was used to strengthen the foamed concrete mix.The results showed that the use of 1.5% of C has affected the modulus of elasticity and flexural toughness of foamed concrete.On the other hand, a strong relationship is found between compressive strength and ultrasonic pulse velocity for FRFC.

Strength Behaviour of Clayey Soil Mixed with Pond Ash, Cement and Randomly Distributed Fibres

An experimental program was undertaken to study the effect of inclusion of pond ash and randomly distributed polypropylene fibres on the strength behaviour of cement-stabilized clayey soil. In the present investigation, 19 combinations of fibre-reinforced cement-stabilized clayey soil-pond ash mixes at three different percentages of pond ash (i.e. 10, 20 and 30%) and two different percentages of polypropylene fibres (i.e. 0.5 and 1%) of length 6 and 12 mm with 5% cement content were prepared. The combinations of clayey soil-cement-pond ash-fibres were subjected to a series of standard proctor test, unconfined compressive strength and split tensile strength tests. Based on favourable test results obtained, it can be concluded that partial replacement of cement-stabilized clayey soil by pond ash with the inclusion of polypropylene fibres causes a significant increase in strength, decrease in the stiffness, and rate of loss of post-peak strength. The fibre inclusion changed the brittle behaviour of the composite to ductile. The inclusion of 1% fibres of 6 mm length or 0.5% fibre of 12 mm length has the same impact on the unconfined compressive strength and split tensile strength of the mixtures. The study demonstrates that pond ash can be used successfully as partial replacement of the clayey soil by using reinforcement and cement.

The effect of using synthetic fibers on some properties of modified juss

This paper examines the mechanical properties of a composite material made of modified Iraqi gypsum (juss) reinforced with polypropylene fibers. The modified juss was prepared by adding two percentages of cement (5, 10) %. Two percentages of polypropylene fibers were used, to reinforce the modified juss (1, 2) %. The water/dry compound ratio used was equal to 0.53%. The composite was evaluated based on compressive strength, flexural strengths, absorption percentage, density, acoustic impedance, ultra - pulse velocity, longitudinal shrinkage and setting time tests. The results indicated that the inclusion of cement on to juss increases the compressive strength, absorption percentage, density, acoustic impedance, ultra - pulse velocity, longitudinal shrinkage and a reduction in flexural strength and setting time were observed by adding the cement. In addition, the inclusion of polypropylene fiber was significant in improving mechanical performance of the composite material, it shows a great improvement in longitudinal shrinkage, modulus of rupture and absorption percentages.

The Influence and Optimization of Treatment Strategy in Enhancing Semiarid Soil Geotechnical Properties

In this article, the effect of randomly oriented polypropylene fiber inclusion in enhancing the various geotechnical properties (unconfined compression strength, compressibility index, swell index, hydraulic conductivity, linear shrinkage, California bearing ratio) of a typical expansive semiarid soil is studied. Since the practicing engineer typically has difficulty in selecting the right mix of fiber type, dosage, and lime content to meet the optimum requirements of this targeted group of geotechnical properties, PROMETHEE is here adopted in order to assist in the decision-making process. The primary objective of this study was to evaluate different geotechnical properties for possible alternatives, the first being untreated soil itself and the second treating the soil with 6% lime. The remaining alternatives vary with fiber type, fiber size, and fiber dosage with or without lime. A further objective was to study the combined influence of factors, viz. lime addition, fiber type, fiber dosage, and fiber length at their respective levels of interactions for the targeted soil properties. The results of the study led to the identification of groups of criteria expressing similar preferences. Sensitivity analysis was carried out in order to better understand the conflicts to be solved in order to make this decision.

Physical and mechanical properties of plasters incorporating aerogel granules and polypropylene monofilament fibres

Growing concern over global warming in recent years has required buildings to become significantly more energy efficient. One of the main ways of achieving this aim has been through the use of innovative materials to facilitate improvements in levels of building insulation. This paper describes the use of aerogel granules as an additive material for lime-based plasters, with the objective of improving the thermal efficiency of buildings whilst maintaining or improving vapour permeability.Five experimental lime composite mixes were prepared, with lime putty as the binder material and aggregate comprising differing proportions of standard sand and aerogel granules. Previous work had already confirmed very low strengths for plaster mixes containing aerogel granules alone as the aggregate material; therefore, polypropylene fibres were incorporated as a secondary additive material to improve the mechanical properties and reduce strength loss attributed to shrinkage and cracking.The flexural strength, compressive strength, thermal conductivity and water vapour permeability of lime composite mortars containing different volume fractions of aerogel were determined. Microstructures were examined using scanning electron microscopy and transmission electron microscopy. The results showed that aerogel granules can be successfully incorporated into lime plasters to improve thermal efficiency. The addition of aerogel was also found to improve moisture vapour permeability. The inclusion of polypropylene fibres in aerogel plasters was effective in reducing shrinkage and cracking to acceptable levels. Experimental mixes exhibited a slight reduction in strength compared to standard plaster mixes, although this was compensated for by a high level of flexibility and toughness.This work provides innovative information on utilising aerogel granules as an insulating plaster additive by addressing the issues of strength and flexibility, properties that are not normally associated with aerogel but which are of importance in a functional plaster material.

Influence of Fly Ash on the Properties of Self-Compacting Fiber Reinforced Concrete

Self-compacting concrete (SCC) has high flow ability and high resistance to segregation and bleeding. These characteristics facilitate the mixing, casting and finishing of SCC without using compacting or vibrating machines. Adding mineral admixtures, such as fly ash (FA), and superplasticizers improves SCC properties by preventing segregation and bleeding and by increasing rheological parameters. SCC requires high flow ability under the influence of self-weight to completely fill all mold parts for full compaction. This paper discusses the results of an experimental investigation on the properties of SCC and self-compacting fiber reinforced concrete (SCFRC) mixtures with the inclusion of polypropylene fibers (PFs) and containing FA at replacement rates of 0%, 20%, 40%, and 60 % cement mass. The compressive, flexural, and split tensile strengths of the prepared concrete samples were investigated at ages of 7, 14, 28, and 90 days. The workability of fresh concrete mixtures was also studied through segregation, bleeding, slump flow, slump flow T50, L-box V-funnel T5, and V-funnel tests. Results showed that the best properties of fresh SCCs were obtained when FA was added at replacement rates of 20% and 40% cement mass. In addition, the inclusion of PFs at a volumetric ratio of 0.22% decreased segregation and bleeding and improved the flexural and tensile strengths of SCFRCs.

Hydro-mechanical behavior of polypropylene fiber reinforced expansive soils

This paper presents a series of laboratory tests and evaluates the effect of polypropylene fiber inclusion on volume change behavior and soil-water characteristics of expansive soils. Specimens were statically compacted at maximum Proctor dry density and optimum moisture content with 0%, 0.5% and 1% polypropylene fiber inclusions by dry weight of the soil, and their volume change behavior was studied through swell-shrinkage and consolidation tests. The soil-water characteristic behavior, which is the most significant aspect of soils, was also obtained by a series of matric suction measurements using filter paper technique. It was concluded that polypropylene fiber inclusion is very effective in reducing the compression and swell indices and swell pressures as well as one-dimensional swell amount in saturated condition. Upon desiccation, shrinkage of reinforced soil reduced considerably, as the shrinkage limit increased by more than 50%. Therefore, fiber reinforcement can effectively reduce swell-shrink movement of expansive soils.

Evaluation of the Shear Strength Behaviour of Polypropylene and Carbon Fibre Reinforced Cohesive Soils

The purpose of this study is to investigate the influence of various parameters involved, such as the strength properties of fibres, the relative size of fibres and grains and the rate of shear on the shear strength of polypropylene or carbon fibre reinforced cohesive soils with different percentage loading of fibres. The experimental results reveal that the inclusion of polypropylene fibres in soil increases considerably the shear strength. Contrarily, the inclusion of the carbon fibres did not produce a clear beneficial effect. In both cases, the shear strengths results are attributed to the different micro mechanisms involved in the fibre/soil interactions as studied through scanning electron micrographs. A significant outcome from the current work is that the strength of the reinforced soil composites is independent of the fibre mechanical indexes.

Study on the Influence of Polypropylene Fiber and SBR Latex on the Mechanical Properties of Rubber Mortar and Microstructures Analyzed

This paper presents a study on the mechanical properties of rubber mortar with the inclusion SBRL (butylbenzene latex) and PP (polypropylene) fiber and the microstructures of SBR latex modified mortar were analyzed. The results proved for specimens with 20 vol.% of rubber, when the P/C of SBR latex was 10%, the compressive and flexural strength of SBR latex modified rubber mortar was optimal. Besides, for specimens with 20 vol.% of rubber, the compressive and flexural strength of SBR latex and polypropylene fiber modified rubber mortar increased with the inclusion of polypropylene fiber, especially when the P/C of SBR latex was 10%. Through scanning electron microscope (SEM), it was founded that polymer has formed a consecutive reticulate film which has a toughening effect on cement matrix.

Effects of polypropylene fiber inclusion on the strength and volume change characteristics of cement-fly ash stabilized clay soil

ABSTRACT: An experimental investigation was conducted to evaluate the effects of polypropylene fiber inclusions on the geotechnical characteristics of a clayey soil that was chemically stabilized with cement and fly ash. For all stabilized soils, cement and fly ash were added at 8% and 30%, respectively. Reinforced stabilized soil specimens were prepared at four different percentages of fiber content (0.25%, 0.50%, 0.75%, 1.0%) and three different fiber lengths (6 mm, 12 mm, 20 mm). Unconfined compressive and split tensile strength tests were carried out after 7- and 28-day curing periods. The volume change characteristics of the reinforced stabilized soil were determined using shrinkage limit and crack reduction values. The interactions between the fiber surface and the stabilized soil were analyzed by means of scanning electron microscopy. According to the results, the compressive and especially the tensile strength values increased to a great extent following the addition of fiber into the stabilized soil. The highest strength values were obtained with 0.5–0.75% content for the 12 mm-long fibers. The shrinkage limit and crack reduction values increased with increased fiber content and greater fiber length, whereas volume changes decreased.

Explosive Spalling of Concrete Columns with Steel and Polypropylene Fibres Subjected To Severe Fire

The exposure of concrete elements to high temperatures during fire can cause major risk to life safety and to the serviceability of a building. One of the main reasons for this is due to concrete spalling which caused by pore pressure and thermal stresses. Previous research has indicated that the inclusion of polypropylene fibres to concrete reduces explosive spalling. However, concrete containing polypropylene fibre can still be vulnerable to explosive spalling during fire. This paper presents the outcomes of a research investigating the effect of using steel fibres in addition to polypropylene fibres to reduce explosive spalling of concrete. The experimental part of this study evaluates the performance of six normal strength columns under a loading ratio = 60% of the design capacity and subjected to severe heating rate higher than ISO 834. The columns were cast using various dosages of steel and polypropylene fibres. Analyses of the main findings included evaluation of the measured concrete temperatures along with axial displacement recordings. The analysis demonstrates a clear assessment of the spalling levels of the various representative specimens. The study also compares the experimental axial displacement with theoretical predictions using DIANA. Conclusions drawn from the study indicate that adding steel fibresalong with polypropylene fibres can reduce the degree and severity of spalling if compared with concrete containing polypropylene fibres only. The spalling degree was reduced from 22.03% to 12.41% in best case and from 14.95% to 10.49% in average when steel fibres were used with polypropylene fibres.