PP Fiber Research Articles

Analyzing the microstructure of cemented fills adding polypropylene-glass fibers with X-ray micro-computed tomography

Fiber reinforced cementitious tailings backfill (FRCTB) is progressively employed in mining industry due to its high strength/stiffness-to-weight ratio. However, the wide use of the FRCTB technique requires further study of the practice of many different types of fibers, either alone or in combination. In this regard, this paper explores the impact of composite (glass-polypropylene) fibers on microstructure of FRCTBs considering weak surface and pore characteristics. The fractures of backfills were quantitatively analyzed by a non-destructive X-ray micro-computed tomography system which permits imagining of the interior microstructures of backfills via the construction of 3D volumetric data in diverse spatial scales. Quantitative parameters cover percent weak surface, porosity, and pore sphericity. The spatial distribution of weak surfaces, pores, and fissures and the bridging effect of fibers were also analyzed based on the 3D reconstruction technique. Adding fibers increased the percentage of FRCTB's weak surface. The greater the glass fiber dose, the larger the percentage of the weak surface. Composite fibers can lessen FRCTB's porosity. The smallest FRCTB porosity was 0.07 % for glass and PP fiber contents of 0.4 wt% and 0.2 wt%, respectively. A rise in glass fiber dose causes a rise in volume of 10–100 mm3 pore content. Fibers have a greater impact on the volume of 0.1–100 mm3 pores, and the rise in glass fiber dose deteriorates shape of this type of pores, leading to a reduction in the sphericity of this type of pores. There is a clear correlation between the distribution patterns of weak surfaces, pores, and fissures along the height of the specimens. Weak surfaces and pores are prone to develop as fractures. Fibers can limit the crack expansion in FRCTB. Lastly, this study presents a time- and cost-saving method for analyzing FRCTB's microstructure.

Optimizing thermoplastic pultrusion parameters for quality long fiber thermoplastic pellets in glass fiber-reinforced polypropylene

A long fiber thermoplastic pellet (LFTP) is a pellet that contains discontinuous fibers reinforced in thermoplastic. In this experiment, LFTPs were produced using the thermoplastic pultrusion process. The thermoplastic pultrusion process is uncomplicated in terms of the machine device, and it can improve the impregnation quality of LFTP. Glass fiber was used as the reinforced fiber, and PP fiber was used as the matrix. This experiment studied the effect of molding temperature and pulling speed on impregnation. The die system contained six heating zones. In the first step, zones 3 and 4 (melting zone) were varied at 200, 210, 220, and 230°C. The melting zone that exhibited good results was selected for the next step. In the second step, zones 5 and 6 (heat reduction zone) were varied at 160°C–190°C and 150°C–180°C, respectively. After determining the optimal molding temperature, the pulling speed was studied, with speeds varied at 10, 20, 30, 40, and 50 cm/min. The impregnated quality of the LFTP was investigated through microstructure analysis. A data logger was used to record the temperature profile in the pultrusion die. Furthermore, the impregnation quality and microstructure of LFTP from thermoplastic pultrusion were compared to commercial LFTP. The results showed that un-impregnation decreased with an increase in the melting zone temperature. In the heat reduction zone, un-impregnation decreased with a decrease in temperature. For the pulling speed, un-impregnation decreased with a decrease in speed. The optimal die system had a melting zone temperature of 230°C and a heat reduction zone temperature of 160 and 150°C. The optimal pulling speed was 10 cm/min, resulting in an un-impregnation rate of 8.06%. Additionally, commercial LFTP had an un-impregnation rate of 13.73%.

Post-heating evaluation of fibre reinforced concrete with LC3 binder as replacement to OPC

Limestone calcined clay cement (LC3) is an emerging cement that uses reduced clinker content in production, leading to a sustainable future by reducing CO2 emissions. Compared to OPC, LC3 has performed well under normal conditions. But the residual strength of LC3 binder concrete can differ from that of OPC-based concrete at high temperatures. This experimental study highlights the effect of elevated temperature, various cooling conditions and inclusion of fibres (PPF, SF, HF) on the physical properties such as colour change, crack width, mass loss and residual compressive strength of concrete monitored using both NDT techniques and destructive testing. NDT comprised rebound hammer and UPV test carried before and after cooling heated samples. After compression testing, X-ray diffraction was used to determine the samples' microstructure and phase shift (XRD). Test results show that the compressive strength and mass loss increased significantly after exposure to 200 °C due to further hydration of un-hydrated clinkers. The performance decreased sharply after 600 °C exposure due to the decomposition of hydration products. Steel fibre had a beneficial effect, but PP fibre, due to balling, reduced concrete compressive strength. At all exposure temperatures, water quenching significantly decreases compressive strength. This reduction can be attributed to micro-crack formation caused by high thermal stress.

Laboratory evaluation of the effect of microfibers on the low-temperature cracking performance of grouted macadam mixtures

Grouted Macadam (GM) mixtures are a composite of bituminous and cementitious phases used as pavement semi-flexible overlays because of their high static bearing capacity and rutting resistance, good durability, and proper resistance to chemical attacks and fossil fuels. However, these mixtures do not have good performance at low temperatures. Reinforcement by fibers is a popular method to improve the performance of asphalt and concrete mixtures and has the potential to be used to reinforce GM mixtures. This study aims to reinforce both bituminous and cementitious phases of GM mixtures using glass based (Microcorta) and polypropylene based (PP) fibers, respectively. The bituminous phase of the first group of the GM mixtures was reinforced with 0.2, 0.4, and 0.6 vol% of glass microfibers (MC). In addition, 0.2, 0.3, and 0.4 vol% of PP fibers were used to produce the cement grout of the second group of GM mixtures. In the next step, the performance of each group was compared with that of the fiber-free samples using a three-point bending test (TPB) and low-temperature indirect tensile test (IDT). Based on the obtained results, GM mixtures’ best low-temperature performance in both IDT and TPB tests was obtained for mixtures containing the highest percentage of fibers (0.6% of MC and 0.4% of P.P fibers). Also, it was observed that the reinforcement of the bituminous phase increased the fracture strain tolerance (FST) in the TPB and IDT tests by 66.19% and 25.01%, respectively, compared to fiber-free samples. Moreover, using fiber-reinforced cement grout has been able to enhance the FST index in the TPB and IDT tests by 91.87% and 30.9%, respectively, compared to fiber-free samples. Overall, the results demonstrate that the reinforcement of both bituminous and cementitious phases of GM mixtures by microfibers can help improve their ability to resist low-temperature cracks.

Research on dynamic mechanical properties of polypropylene fiber-modified rubber foamed concrete

To investigate the dynamic properties of polypropylene fiber-modified rubber foamed concrete (PPR-FC), foamed concrete (FC), and foamed concrete with recycled rubber granules (R-FC) specimens with wet densities of 700 kg/m3, 800 kg/m3, and 900 kg/m3 were prepared for evaluation of dynamic performance (including dynamic elastic modulus and impact resistance) and unconfined compressive strength. The test results showed that PPR-FC was density-dependent. The polypropylene fiber (PP fiber) was helpful in improving the toughness of the material. In particular, the improvement of the unconfined compressive strength and impact performance based on the destructive test was more obvious, with a maximum increase of 18.15% and 78.34%, respectively. The impact performance was determined by the maximum number of impacts that can be withstood. The rubber granules increased the specimen’s ductility, which is positive to impact resistance with the maximum improvement of 470.41%, meanwhile increasing the wet density that can effectively remedy the decrease of the unconfined compressive strength and dynamic elastic modulus. Moreover, the dynamic elastic modulus was positively related to the frequency as a whole due to the strain rate effect. Then, the microscope test showed that fiber can connect the bubble structure, making the bubble structure more stable, but also increasing the number of irregular and large-diameter bubbles. The rubber granules changed the shape of bubbles around the granules, and increased the number of large-size bubbles, while decreasing the overall number of bubbles. Finally, according to the test results, the prediction formula of dynamic elastic modulus and impact resistance based on multiple factors was established. As a result, this paper can provide a reference for the application of PPR-FC in engineering practice.

Repeated impact behavior of preplaced aggregate concrete incorporating different fiber types

This research used an experimental approach to examine the impact performance of preplaced fibrous aggregate concrete with various fibre types. Four concrete mixtures were produced with identical quantities except for the type of fiber. The first reference mixture was plain, while the other mixtures were reinforced with 2.5% of polypropylene fibers (PP), short steel fibers (SF1) and long steel fibers (SF2). In accordance with the ACI 544-2R impact test method, six cylindrical discswere tested from each mixture using drop-weight impact loading. The tests' results revealed that adding fibre, irrespective of the type of fiber used, considerably enhanced the impact strength at the cracking (Ncr) and failure (Nf) phases. Compared to their plain concrete specimens, fibrous specimens showed increased Ncr ranging from 395 to 655% and Nf from 727 to 1973%. Steel fibers exhibited higher impact strength by 33 to 151% and higher ductility by 44 to 64% compared to PP fibers. Besides, a longer steel fiber performed better under impact loads than shorter steel fibers, where Ncr and Nf were higher by 14 and 31%, respectively.

Analysis of stress-strain behavior in engineered geopolymer composites reinforced with hybrid PE-PP fibers: A focus on cracking characteristics

Engineering geopolymer composites (EGC) are a promising low-carbon and highly durable composite material. However, the high cost of materials hinders its engineering application. To address this challenge, this study investigates the use of cost-effective PP fibers to partially or completely replace PE fibers, and develops an economical hybrid PE/PP-EGC. Axial tensile experiments were conducted on PE/PP-EGC with different PP fiber replacement ratios (0%, 25%, 50%, 75%, and 100%) to investigate the effect of PP fiber replacement ratios on the tensile behaviour of PE/PP-EGC. Economic feasibility of PE/PP-EGC is also evaluated. The results show that when the replacement ratio is below 75%, PE/PP-EGC still exhibits pseudo-strain hardening and multiple cracking characteristics. As the replacement ratio increases, the crack control ability of EGC decreases, resulting in an increase in the average crack width and a decrease in the crack density. PE/PP-EGC with a replacement ratio of 50% has a highest ultimate tensile strain (9.71%), which is 68% higher than that of PE-EGC, while the tensile strength is only reduced by 15%. Furthermore, PE/PP-EGC with a replacement ratio of 50% exhibits the highest tensile strength, ultimate tensile strain, and tensile strain energy per unit cost. Based on the experimental data and theoretical derivation, this study proposes a semi-empirical bilinear tensile constitutive model of PE/PP-EGC and verifies its reliability. It is recommended to use a 50% replacement ratio of PP fibers for PE/PP-EGC, which offers optimal tensile mechanical performance, along with outstanding comprehensive economical performance. These research findings provide important insights into the design and application of low-cost and high-performance engineering geopolymer composites, and could have significant implications for the development of sustainable and durable infrastructure.

Prediction of high-temperature creep in concrete using supervised machine learning algorithms

In this paper, supervised machine learning techniques were employed to develop a prediction model for concrete creep at elevated temperatures. Several algorithms were considered including artificial neural networks (ANN), decision tree regression (DTR), random forest regression, linear regression and Gaussian process regression (GPR) models. A dataset of short-term, basic creep was compiled from experimental data reported in the literature for algorithm training. The selected input variables were time, temperature, 28-day compressive strength, compressive stress, fine and coarse aggregate mass, and steel and PP fiber mass. The data was split into training and verification sets, with 70% used for model training and the remaining 30% for model verification. The results demonstrate that ANN, DTR, RFR and GPR models can accurately reflect concrete creep behavior at elevated temperatures based on statistical indicators. However, further analysis showed that the GPR was the best-performing model, providing highly accurate representations of creep behaviour and demonstrating superior performance to existing empirical equations. Conversely, the DTR was found to not accurately reflect experimental data. Additionally, a Shapley additive explanation analysis was conducted that assessed the significance of each input parameter on model prediction. This research highlights the potential of machine learning techniques to accurately model high -temperature concrete creep behavior and thus represents a powerful tool for engineers and researchers.

Cost-Effective Engineered Cementitious Composites with Hybrid PVA and Basalt/PP Fiber: A Study on Compressive, Tensile and Impact Performance.

Currently, oil-coated PVA fibers are the most commonly used material in ECC research. However, the high price limits the application of PVA-ECC in practical engineering. In order to reduce the cost, one of the methods is to partially replace the PVA fibers in ECC. In order to demonstrate the feasibility of PVA/BF-ECC and PVA/PP-ECC, polyvinyl alcohol fibers (PVA), basalt fibers (BFs) and polypropylene fibers (PP) were added at 0.5%, 1.0% and 1.5% by volume of PVA in addition to 1% by volume of PVA. Subsequently, tensile, compression and drop-weight impact tests were conducted on single or hybrid fiber concrete. The results showed that the post-peak compression toughness, tensile strength, and initial cracking impact strength of PVA/BF-ECC and PVA/PP-ECC increased significantly with the increase in the volume ratio of BF and PP fibers, while the performance of PVA-ECC materials with the same fiber volume ratio decreased slightly. Therefore, the cost can be reduced by designing hybrid PVA/BF-ECC materials that meet the performance requirements. The experimental evidence presented in this study demonstrates the feasibility and reasonable prospect of the new hybrid PVA/BF-ECC.

Novel flexible phase change materials with high emissivity, low thermal conductivity and mechanically robust for thermal management in outdoor environment

High summer temperatures will become the norm as global warming intensifies due to massive energy consumption and greenhouse gas emissions. High-temperature environments will seriously threaten the health of outdoor workers. It is urgent to adopt new technologies to solve the problem of reducing the thermal stress of workers in an extremely hot environment. Herein, phase change material (PCM) and radiative sky cooling technology were combined and prepared successfully a new kind of flexible composite phase change material (CPCM) with paraffin wax (PW), polypropylene hollow fiber (PP fiber) and Linear styrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer with 30 wt% styrene (SEBS). Compared with the traditional end sealing technology, the melted SEBS can close the end of the fiber easily and cost-effectively. The novel material (10PP) has a high enthalpy of 180.01 J/g, and the thermal conductivity is as low as 0.26 W/ (m· K), the low thermal conductivity of CPCM reduces the transfer of heat from the outside to the inside. Tensile strength is 3.89 MPa, the maximum force that 10PP can withstand reaches 147 N, and the contact angle for the hydrophobicity test is 114.8°, which provides a guarantee for the wide application of the new material in an outdoor environment. Besides, the optical test shows an emissivity (atmospheric window) of 0.955, and the extremely high emissivity facilitates radiative cooling of the material at night. On a clear day, the average temperature difference and maximum temperature difference between 10PP and the environment are 6.403 °C and 13.414 °C respectively. In the simulation experiment of the tent, when the external temperature reaches 60 °C, the surface temperature of the tent with CPCM is about 22 °C lower than that without CPCM. This inspiring work offers a great contribution to flexible passive cooling materials for outdoor applications.

Microscale failure analysis of the ultra-high-performance polypropylene fibre reinforced concrete panel subjected to high thermal loading induced by fire exposure

To date, many buildings are prone to fire from non-structure systems like high-pressure laminates and insulated cladding systems. Ultra-high-performance concrete (UHPC) has been applied to the cladding systems due to its excellent mechanical properties at room temperature and non-flammable characteristic. To improve its mechanical properties under fire condition, different fibres like PP fibre have been employed to reinforce UHPC. The tensile strengths of these ultra-high-performance PP fibre reinforced concrete (UHPPFRC) panels vary due to the different orientations of internal PP fibres. However, few studies have been carried out on the internal stress and fire resistance of these claddings. Study on understanding the fire behaviours and failure process of the UHPPFRC panel is essential for developing claddings with better fire resistance and durability. In this study, a coupled hygro-thermal–mechanical model is developed to predict the internal stress and temperature distribution within the UHPPFRC panel. The microscopic failure process of PP fibre and porosity change within the panel during heating are all embodied in the model, and its accuracy has been validated. The initial and the residual tensile strengths of the UHPPFRC panel are considered to fluctuate between two extrema due to the random fiber orientation. Based on this, Program Evaluation and Review Technique (PERT) is applied to investigate the effects of fibre dosage and heating rate on retarding crack propagation and failure of the UHPPFRC panel under high temperature. Results from the numerical investigation indicate that 0.55% dosage of PP fibre can effectively postpone crack occurrence and propagation within the UHPPFRC panel at linear elastic phase, and faster heating rate can accelerate the pore pressure generation process. Also, internal fibre orientation is a significant factor affecting the fire endurance of the UHPPFRC panel subjected to elevated temperature, which should be considered for safety and reliability evaluation of the structure.

Impact of elevated temperatures on the mechanical properties and microstructure of waste rubber powder modified polypropylene fiber reinforced concrete

To investigate the impact of elevated temperature on the residual mechanical properties and microstructure of waste rubber powder modified polypropylene fiber concrete (RPFC). A total of 20 mix proportions were designed, considering the effects of waste rubber powder (WPR) dosage, polypropylene fiber (PP fiber) dosage and different ambient temperatures on the mechanical properties and microstructure of RPFC. Surface color change, weight loss, residual compressive strength of RPFC were evaluated after exposure to 100C, 200C, 400C and 600C. Meanwhile, the digital image correlation (DIC) technique was adopted to monitor the surface crack development of prism specimens at different loading stages. By X-ray diffraction (X-RD) analysis and scanning electron microscope (SEM) observation, the chemical and physical changes of RPFC were explored comprehensively. The results showed that the weight loss of RPFC increased after high temperature and the microcracks on the surface of the specimen increased significantly with the WRP content increase at 600 °C. Below 200 °C, the strength loss rate of RPFC is lower than that of PP fiber concrete; it is significantly higher in 400C than that of PP fiber concrete. RPFC exhibits lower intensity in the X-RD curve than that of PP fiber concrete. The needle-like channels and pores formed thanks to fibers and WRP melting helps to release the vapor pressure and improve the concrete resistance to bursting. Finally, the relationship between ambient temperature and compressive strength was established.

Mix proportion optimization and early strength development in modified foam concrete: an experimental study

The influence of the single polycarboxylate superplasticizer (PCE) and blending it mixed hydroxypropyl methylcellulose (HPMC) on hardening moulding quality and surface pulverisation of foam concrete was investigated. An orthogonal experimental design was employed to determine the optimum combination of parameters for four property indexes (PIs) in this paper. A multi-index matrix analysis method was used to evaluate the parameter combinations and obtain the overall optimal performance for the PIs. The effect of calcium formate (CaF) on the early compressive strength of modified foam concrete with the most optimal combination in different density grades was also studied. The results indicate that the incomplete cement hydration reaction is the essential cause of pulverisation, which can be alleviated by adding a suitable PCE. Defoaming and precipitation occur when the PCE incorporated exceeds 0.1%, which can be mitigated by the addition of 0.02 to 0.06% HPMC. The orthogonal analysis indicates that the anti-cracking agent has a more substantial effect on the strength of the foam concrete than the thickening agent. The most significant factor of mechanical properties is PP fiber followed by dispersible latex powder (DLP). The optimal combination of foam concrete is 0.06% HPMC, 0.3% DLP, and 0.5% PP fiber. The early compressive strength of foam concrete can be significantly enhanced by increasing the CaF content. However, increasing the density level results in a decrease in the 28-day compressive strength of the foam concrete.

Effects of microsilica and polypropylene fibers on the rheological properties, mechanical parameters and durability characteristics of green self-compacting concrete containing ceramic wastes

In the developing countries, since a major part of the urban wastes is related to the construction sector, this study has used ceramic waste (CW) as a partial substitute for natural coarse aggregates to produce self-compacting concrete (SCC), and since the latter should have enough strength and durability, effort has been made to not only examine its rheological properties and mechanical parameters, but also study the effects of microsilica (M) and polypropylene fibers (PP fibers) on its durability characteristics (electrical resistivity, ultrasonic pulse speed and volumetric and capillary water absorption). According to the results, increasing the percent CW decreases the SCC efficiency, and increasing M and PP fibers increases its viscosity and, hence, decreases its flowability and passability, but increases its resistance against segregation. In this research, CW50M10P0.15 had the highest compressive strength – an increase of about 21% compared to the control sample – and CW25M5P0.3 showed the highest tensile and flexural strengths compared to the control sample. Adding CW reduced the durability of the SCC samples slightly, but adding M and PP fibers increased it. In the electrical resistivity test, CW25M10P0.3 showed an increase of about 168% compared to the control sample. Analyzing the scanning electron microscope (SEM) images revealed that mix designs containing ceramic wastes had a stronger ITZ, and adding M made the samples denser and more coherent.

Flexural behavior of structure of laminated cementitious composites with different types of mesh reinforcements

In this study, 17 plates of cementitious ferrocement composite structure reinforced with two types of fabrics (jute and polypropylene) derived from biaxially oriented jute and polypropylene canvas with three reference unreinforced plates are experimentally investigated. The aim was to increase the flexural load carrying capacity and ductility of unreinforced laminated composite. The matrix was prepared using a ratio of 1:2:0.3 (Portland cement: sand: fly ash) by weight and water-to-cementitious material ratios (w/cm) of 0.4, 0.5, and 0.6. In accordance with ASTM C1609 procedure, the structural behavior of studied laminated composites with a size of 450 × 100 × 25 mm under a four-point load configuration, including first crack, maximum post cracking strength or modulus of rupture (MOR), deflection, toughness, crack pattern, and failure modes, are investigated with the effectiveness of type of fiber and the number of fabric layer reinforcements. The results indicate that types of fiber and number of layers of fiber have a significant effect on enhancement of resistance, strength, and ductility of the cementitious material mortars. The results showed that the first cracking strength generally decreased as the number of fibric layers increased. In comparison to the reference plates, the first cracking strength decreased by 92.8, 83.0, and 34.3% for plates reinforced with polypropylene fiber at 0.4 w/cm, as layer number increased from zero to six, eight, and ten, respectively. The post-flexural strength of the jute fiber-reinforced plates increased as layer number increased relative to the reference plate, whereas this was completely the opposite for polypropylene fiber-reinforced plates. The maximum flexural strength was 10.82 MPa for plates reinforced with jute fabrics whereas polypropylene fibers had a maximum flexural strength of 5.21 MPa. The post flexural strength of plates reinforced with jute fiber increased for w/cm ratio of 0.6 by 2.1, 68.0, and 78.4%, whereas it dropped for plates reinforced with polypropylene fiber by 6.7, 9.0, and 53.6% as layer number increased from zero to six, eight, and ten, respectively. Polypropylene fiber reinforced plates have a wider crack width than jute fiber reinforced plates and the effect of increasing layer number was not clear, but it did generally reduce crack spacing. A comparison of the maximum post-cracking strength against the first cracking strength indicated that jute fiber plates exhibited deflection hardening behavior, while the behavior was completely reversed for plates reinforced with PP fiber, whose curve behavior was softening deflection. The maximum deflection recorded 18.5 mm, and the energy absorption and deflection capabilities of jute fabric reinforced composites have both improved with layer number increased. Conversely, for polypropylene fabric reinforced composites, where the maximum deflection was 21 mm and the deflection and energy absorption capacity decreased as layer number increased. However, laminates made of polypropylene fabrics displayed significantly weaker bonds than jute fabric laminates, resulting in the appearance of horizontal cracks that separated the Polypropylene laminate layers and spread towards both supports emphasized by SEM test. As a result, the indices described in ASTM C1608 specifications cannot be generalized to the behavior of such materials for such a curve because, based on the experimental data, the calculated residual strength ratio exceeded 100% in only three plates. The toughness values in the composites suggest that this eco-friendly, ductile composite has a promising future in the construction industry.

Optimization of production parameters of novel hybrid fiber-reinforced geopolymer mortar: Application in masonry walls

Earthquakes cause heavy damages to occur in masonry walls, largely due to the use of low-strength mortar. The scope of this study aimed to produce a new mortar with higher strength, which does not use cement as a binder, instead of the mortars currently used as a binder. In the first stage, geopolymer mortar samples were prepared and the sample that gave the optimum results selected as the reference mix for fiber mixes. The highest compressive strength value was obtained in mixtures with Na2SiO3/NaOH (10 M) = 2 at mixing ratios. Then, seven different combinations were created for three different fiber types (carbon, glass and PP fiber). Among these mixtures, subjected to compression and flexural test with fiber combination in the produced samples, the mixture with the highest mechanical properties was used in masonry wall production. The compressive and flexural strength values of optimum fiber-reinforced KR2 geopolymer mortar mixture under ambient conditions were obtained as 44.1 and 8.1 MPa, respectively. Significant increases were obtained in the compressive and flexural strengths with the increase in carbon fiber content in hybrid fiber ratios. Then, a uniaxial compression and diagonal test was applied to the walls produced with both normal mortar and geopolymer mortar. When the results are examined, the masonry wall prepared with fiber-reinforced geopolymer mortar (GPM) carried a load of 550 kN under vertical loading system, while the wall prepared with normal mortar carried a load of 147 kN under diagonal test. Through the experiments, it was determined that the walls produced using fiber-reinforced geopolymer mortar have higher shear and compressive strength values than the walls prepared with standard cementitious mortar. While the wall samples produced with cement-based standard mortar collapsed under the uniaxial compression test, the wall samples produced with fiber-reinforced geopolymer mortar showed ductile behavior and no sudden failures occurred under diagonal loading tests.

Performance Evaluation of Fibre Reinforced Concrete Containing Alccofine and Zeolite

Objectives: The intent of the study is to assess the strength and durability behavior of concrete specimens attaining micro fillers such as alccofine and zeolite and micro reinforcement in the form of polypropylene fibres. Methods: Polypropylene fibres were added in volume fractions of 0%,0.1%, 0.2%, 0.3% and 0.4%. The mechanical properties of concrete such as compressive strength, modulus of elasticity and flexural strength were obtained for concrete mixes with and without PP fibres through standard testing procedure. Some durability properties such as water absorption, porosity, sorptivity, acid resistance were also examined. Appropriating instrumentation has been adopted for making the measurements pertaining to the above parameters. Findings: Introduction of micro fillers and polypropylene fibres caused a significant effect on as compressive strength, modulus of elasticity, flexural strength, water absorption, porosity, sorptivity, and acid resistance. The results indicated that inclusion of polypropylene fibers exhibit maximum increase of 15.15% and 14.87% has been realized in the compressive strength of cube and cylinder, a maximum increase of 10.47% in flexural strength and 14.35% in elasticity modulus through the inclusion of polypropylene fibre. Novelty: The article reveals that inclusion of micro fillers and polypropylene fibre reinforced concrete in public spaces is a promising practice, since they are impacted by adverse environmental conditions, suffer surface degradation, and are the target of vandalism. It is clear that using concrete with improved characteristics will be advantageous. Keywords: Alccofine; Compressive Strength; Durability; Elasticity Modulus; Zeolite; polypropylene fibre

Flexural fracture parameters of polypropylene fiber reinforced geopolymer

Geopolymer concrete is an effective solution for widely limiting the negative environmental impacts of the cement manufacturing world. In this research, the polypropylene fibers (PP fiber) with various volume fractions, lengths, reinforcing index as well as water-binder ratios (WBR) were mixed into geopolymers to evaluate the effect on their FrT (fracture toughness). A total of 28 experimental groups of different polypropylene fiber geopolymers were considered. In the three-point bending fracture examination, the deformation and displacement fields of polypropylene fiber reinforced geopolymer (PPFRG) notched beams during the fracture process were observed through digital image correlation (DIC). The results show that, the fiber reinforcing index can be used to consider the influence of fiber length and fiber content. In increasing the reinforcing index, the FrT first increased, but after reaching the peak, it decreased. In terms of fracture properties, the PPFRG with a low WBR (0.35) is generally more significant than that of a high WBR (0.38). Comparing the PP fiber with the other fibers in literature, the more substantial toughness enhancement effect and better economy of PP fiber have been proved. Furthermore, this paper established a fracture toughness calculation model through regression analysis.

Performance Evaluation of Hybrid Fibre Reinforced High Volume Fly Ash based Self Compacting Concrete

Self-compacting concrete has become increasingly popular lately for usage in crowded concrete-reinforced buildings having challenging casting circumstances. New cement needs to have high fluidity and strong cohesion for these applications. The necessary concrete characteristics can be ensured through the use of fine elements like fly ash. The preliminary findings of a trial to produce and assess SCC created using large amounts of Fly ash is given and discussed. During this investigation, few SCC combinations and a control concrete is examined. The water/cementitious material ratio is ranges from 0.35 while cementitious material amount remained constant (300 kg/m3). Its self-compacting mixes replaced 25%,35%,37.5%,40%, and 50%, of the cement with fly ash. All mixes were put through tests to determine their viscosity and stability as fresh concrete. Additionally, the compressive strength, Flow Ability Test, Flexural strength and Split Tensile Strength of cured concretes were measured. For the purpose of testing the flow characteristics and mechanical properties of Hybrid Propylene Steel Fibre Self-Compacting Concrete (HPSscc), Steel Fibre in combination with Poly Propylene PP Fibre (Hybrid Fibre) are used to regulate SCC at concentrations of 0.25+0.15%, 0.50+0.30%, 0.75+0.45%, 1.0% + 0.60%, and 1.25+0.75%.The ideal quantity of hybrid fibre is established. The 28-day compressive strengths of the SCCs ranged from 35 to 54 MPa. It is important to research the effects of adding steel fibres to control SCC of various types, aspect ratios, and volume fractions. Concrete can benefit from having its tensile strength increased by using synthetic fibres like polypropylene PP. It is important to achieve the ideal quantity of PP fibres to be added for a specific characteristic of the mix's constituents. Hybrid fibre is used in concrete when more than one fibre is included. The performance of concrete can be improved by using the characteristics of one type of fibre with another type of fibre. Also Flow Ability Test carried out immediately after producing concrete earlier and Split Tensile Strength tests are conducted. The outcomes demonstrate that a cost-effective SCC might be successfully constructed by adding significant amounts(35%) of fly ash.

Mechanical and Thermo-Mechanical Performance of Natural Fiber-Based Single-Ply and 2-Ply Woven Prepregs.

This paper presents a study conducted on prepregs manufactured by a novel method for the impregnation of a thermoplastic matrix. Different composite prepregs based on polypropylene and reinforced with natural fibers (e.g., basalt and jute fibers) were developed. The mechanical and dynamic mechanical properties were investigated. DMA tests were conducted at 1 Hz frequency and properties such as storage modulus and damping (tan δ) were evaluated. The overall mechanical properties of the basalt fiber composites were found to be superior to that of the jute fiber-based samples. Thermo-gravimetric analysis (TG/DTG) of the composite samples showed that the thermal degradation temperatures of the basalt-based composites shifted to higher temperature regions compared to the PP or jute fiber composites. The addition of basalt fiber considerably improved the thermal stability of the composite samples. Microscopic images of the tensile fractured composite samples illustrated better fiber-matrix interfacial interaction due to the novel technology of prepregs. Single-ply and 2-ply prepregs showed significantly superior mechanical, thermal, and thermo-dynamical performance compared to the control sample (pure PP). 2-Ply composites demonstrated higher modulus, tensile strength, and storage modulus due to the higher fiber volume fraction. Basalt-based samples showed a minimum weight loss of about 57% up to 700 °C in contrast to 96.05% weight loss in the jute-based samples and 98.4% in the case of pure PP. The heat resistance index (THRI) is more than twice for basalt compared to jute and PP. Furthermore, the superior thermal stability of basalt is reflected in its DSC curves, showing the highest endothermic peak. The technique of using the resin in the form of thermoplastic yarns offers cost effective and efficient alternatives for composite manufacturing.