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On reducing greenhouse gas emissions by the cement industry, geopolymer with an amorphous polymer form was the best alternative. Geopolymer concrete (GPC) was weak in impact strength, brittle, ductile, and energy absorption than conventional cement concrete. Various property fibres with the capacity to improve the aforementioned properties of GPC can be added. Polypropylene fibre with low elastic modulus and waste tire rubber fibre with high elastic modulus was used in this research to improve energy absorption and impact strength. Different modulus fibres such as polypropylene and rubber was added by 0%, 0.5%, 1%, 1.5% and 2% of volume fraction. The effects of adding individual fibres on the mechanical property of eco-friendly geopolymer concrete were studied. In addition, the influence of hybrid fibres on the mechanical features of low-calcium geopolymer concrete was assessed. The research results revealed that the hybridization of 0.5% of polypropylene fibre and 0.5% of rubber fibre showed better performance and achieved maximum strength in all mechanical features such as compressive, flexural, and splitting tensile behaviour. Meanwhile, the optimum hybrid fibres increased the mechanical features by 23.9%, 12.0%, and 15.2%, respectively, at the 28 days of curing ages compared to geopolymer concrete without fibres.

Paver blocks are manufactured from zero-slump plain concrete, which is small element used for outdoor applications and flexible road surfaces. IS:15658 (2006) permits the use of 33- grade ordinary Portland cement (OPC) as the minimum for manufacturing paver blocks, but the usage of this type of cement is restricted in India nowadays. In this context, we have studied OPC 43-grade cement replaced by 30% Class F-grade fly ash and the addition of 0.0% and 0.5% polypropylene fibre (PPF) to evaluate the suitability of paver blocks in terms of the climatic conditions, movement of vehicles and road surfaces in India. The synergistic effect of the mechanical properties of paver blocks revealed that a 30% replacement of OPC with fly ash and 0.3% PPF is more suitable for the manufacturing of paver blocks. The obtained results from the reference mixes indicated that the mechanical properties of paver blocks have increased with respect to the age of the blocks. The present study is important for paver block manufacturers as it fulfils the mix design, strength and durability requirements for Indian roads associated with the utilization of waste materials such as fly ash. Additionally, the study will help the national economy increase by 20% in the future, along with the sustainability of virgin materials.

To popularize the complete replacement of natural sand with manufactured sand, a study was performed to determine the effect of adding polypropylene fibres (PPFs) to increase the bending strength and carbonization resistance of manufactured sand concrete (MSC). A 2 × 3 factorial design with the content and length of PPF as variables was used to establish a carbonization depth prediction model and a response surface model (RSM). The phase composition and microstructure of polypropylene-fibre-reinforced manufactured sand concrete (PPF-MSC) were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show the addition of PPF with different contents and lengths increases the bending strength of PPF-MSC to varying degrees, while reducing the carbonization depth and increasing the dynamic elastic modulus after 28 days of carbonization. The highest bending strength (6.12 MPa) and carbonization resistance of PPF-MSC are obtained by the addition of 1 kg/m3 of 12 mm PPF, while the carbonization depth and an increase in the dynamic elastic modulus after 28 days of carbonization are maintained at a minimum of 2.26% and 1.94 mm, respectively. A prediction model was established to obtain a formula for the PPF-MSC carbonization depth in terms of the content and length of PPF and the carbonization time. The following results were obtained from the RSM: compared to the PPF length, the PPF content has a larger impact on the PPF-MSC bending strength and a smaller impact on the PPF-MSC carbonization resistance; there is no significant interaction between the content and length of PPF; and the predicted and measured values are close, indicating that the model is highly reliable. A comparison of the XRD patterns and SEM micrographs of PPF-MSC and MSC after 28 days of carbonization show a lower peak intensity of CaCO3 in the pattern for the carbonized area for PPF-MSC than for MSC and considerably fewer surface pores and cracks in PPF-MSC than in MSC. These results indicate that the addition of PPF increases the compactness of MSC and creates an effective resistance to the erosion by water molecules and carbon dioxide (CO2), thus enhancing the bending strength and carbonization resistance of MSC.

Scarcity of the natural sand and large availability of industrial wastes give the way to utilise the industrial by-product in concrete production. This paper showcases the performance of concrete composite containing copper slag and polypropylene fibre under cyclic loading. Fibrillated polypropylene fibre of 0% (P0), 0.2% (P1), 0.4% (P2) 0.6% (P3) volume fractions and 40% copper slag (C40) are used together. The experimental work was conducted on the reinforced concrete beams of size 100mm x 200mm x 900mm. The criteria considered for discussion are yield power, yield deflection, ultimate strength, ultimate deflection, ductility factors and energy dissipation. It is observed that when subjected to monotonic loading and cyclic loading respectively, the overall load carrying power of C40P2 beam is 5 per cent and 2.71 per cent higher than the reference section. The specimen C40P2 has a ductility factor 25.05 per cent higher than the control beam. Energy absorption capacity of C40P2 is 72.79% more than the normal concrete. It is therefore concluded that, under cyclic loading, the output of 40% copper slag with 0.4% of polypropylene fibres find superior than control concrete.

The usefulness of fibre reinforced concrete (FRC) in various civil engineering applications is indisputable. Fibre reinforced concrete has been successfully used so far in construction of structures like bridges, industrial structures, concrete, architectural panels, precast products, offshore structures and many other applications. This paper presents the study on the mechanical properties of the polypropylene fibre reinforced concrete. The parameters varied in the study include volume of fibre (0%, 0.5%, 1.0%, 1.5% & 2.0%) and the curing period (7 days and 14 days). From the study it is concluded that the further increases in the volume of fibre reduces the water cement ratio. The mechanical properties of the polypropylene fibre reinforced concrete were also predicted by using Artificial Neural Network (ANN) and found to have minimal error when compared to actual experimental results.

The mechanical properties of hybrid fibre (polypropylene and wood)-reinforced expanded polystyrene (EPS) lightweight aggregate concrete was studied under various sand contents. Cubic and prismatic compression tests were carried out, through which the basic mechanical properties and stress-strain curves of the specimens were obtained. Moreover, the microstructures of the fibre-reinforced concrete with different sand proportions were analysed via scanning electron microscopy (SEM). The test results showed that as the sand proportion increased, the cubic compressive strength and prismatic compressive strength of the EPS lightweight aggregate concrete increased. The optimal slump was obtained when the sand ratio was 25%, after which the slump declined. The EPS lightweight aggregate concrete exhibited obvious elastoplastic behaviour during compression, and the corresponding stress-strain curve could be divided into four stages: the elastic stage, strengthening stage, softening stage and collapse platform stage. Moreover, based on the test results and the damage theory and considering the coupling relationship between plasticity and damage, a damage constitutive model was proposed for hybrid fibre-reinforced EPS lightweight aggregate concrete under uniaxial compression.

International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies, 13, 7, 13A7H: 1-13

The purpose of this study was to evaluate the appropriateness of polypropylene fibres (PP) to decrease the brittleness of high-performance self-compacting concrete (HPSCC). The influence of PP fibre content on the fresh and mechanical assets of PP-fibre-reinforced HPSCC was investigated. PP fibres were applied with 0, 0.025, 0.05, 0.075, 0.125, 0.25% contents to the HPC blends with high cement replacement by ground granulated blast furnace slag (GGBS). The impact of PP fibre fraction on fresh properties of HPSCC, counting passing capability as well as filling parameters is discussed. In addition, the mechanical properties, i.e., compressive, splitting tensile, and flexural strengths, were evaluated after 7 and 28 days of specimens’ maturation in water. The higher content of PP fibres gradually reduced the HPSCC workability and improved the mechanical properties. The high performance of fresh and hardened ecological HPSCCs containing 46% GGBS instead of cement with 0.025–0.25% PP fibre content proves the great potential of using these composites in various applications in the construction industry. The advantages of the potential recycling of GGBS include, among others, the reduced use of cement in a durable material, reduced amount of waste in landfill and lower emission levels of greenhouse gases.

Protective structures subjected to intensive loads that may benefit from the use of multilayer composite structures with excellent hardness and impact resistance represent an emerging research field in recent times. In this study, low-velocity projectile impact tests were performed on Functionally-graded Preplaced Aggregate Fibrous Concrete (FPAFC) mixtures to evaluate their performance. The effects of projectile needle type, fibre type and hybridization in addition to the number of layers in the composites on projectile impact were investigated. The bioinspiration of the excellent impact strength of turtle shells was used to design an FPAFC comprising a higher amount of steel and polypropylene fibres at the outer layers. In parallel, one and two-layered concretes were also cast to assess the effectiveness of three-layered FPAFC. The tests were performed on disc specimens using non-deformable compound bevel, convex edge and hollow edge projectiles. The damage severity was quantified by the top damage area, bottom damage area and depth of penetration. In addition, a simple analytical model for predicting the composite mass expulsion was developed and implemented. Findings indicated that regardless of fiber type and distribution, the compound bevel projectile needle produced the lowest impact numbers for all single, double and triple-layer specimens compared to the convex edge and hollow edge projectiles. Repeated projectile impacts increased the penetration depth and damaged area at the top and bottom surfaces of all targets. Targets were more resistant to convex edge and hollow edge projectile penetration than the compound bevel. The experimental and analytical model results for mass expelled from the top surface are reasonably acceptable. This research gives an idea of developing advanced fibrous composite with superior impact resistance for the promising protective structures.

Copper slag (CS) is produced during the smelting process to separate copper from copper ore. The object of the experimental research is to find the optimum percentage of CS and PPF volume fraction when CS replaces fine aggregate, and PPF volume fraction when subjected to impact loading. Copper slag was incorporated as 20%, 40%, 60%, 80% and 100% with PPF of 0.2–0.8% with 0.2% increment. The number of blows on failure of the specimen increases as the fibre volume increases. In addition, the energy absorption of composite concrete is higher than that of ordinary concrete. Concrete with up to 40% CS and 0.6% PPF volume shows a 111.72% increase in the number of blows for failure as compared to the control specimen. The impact resistance at failure was predicted by regression analysis, and very high regression coefficients of 0.93, 0.98 and 0.98 were obtained respectively at 7-, 14- and 28-days curing. In addition to regression analysis, a two-parameter Weibull distribution analysis was used to obtain reliable data on the number of blows at first cracking and eventual failure. The energy absorption at 28-day curing period is 1485.81 Nm which is 284% higher than the control mix. Based on the findings, it can be inferred that adding CS up to 60% densifies the microstructure due to its pozzolanic activity, while polypropylene fibre acts as a micro reinforcement, increasing the number of blows.

Engineered cementitious composite (ECC) is a group of ultra-ductile fibre-reinforced cementitious composites, characterised by high ductility and moderate content of short discontinuous fibre. The unique tensile strain-hardening behaviour of ECC results from a deliberate design based on the understanding of micromechanics between fibre, matrix, and fibre–matrix interface. To investigate the effect of fibre properties on the tensile behaviour of ECCs is, therefore, the key to understanding the composite mechanical behaviour of ECCs. This paper presents a study on the fibre-bridging behaviour and composite mechanical properties of ECCs with three types of fibres, including oil-coated polyvinyl alcohol (PVA) fibre, untreated PVA fibre, and polypropylene (PP) fibre. The experimental result reveals that various fibres with different properties result in difference in the fibre-bridging behaviour and composite mechanical properties of ECCs. The difference in the composite mechanical properties of ECCs with different fibres was interpreted by analysing the fibre-bridging behaviour.

Concrete is one of the broadly used construction materials in the construction industry. This research intends to recommend the replacement of conventional coarse aggregates with recycled lightweight expanded clay aggregate (LECA) which offers several advantages such as lightweight, low cost, and easy availability. Lightweight concrete (LWC) offers numerous benefits; therefore, many researchers are using lightweight aggregate to produce lightweight structural composites concrete to compensate heavy loads by reducing the concrete self-weight due to lower density of lightweight concrete, improving in thermal properties and fire resistance, saving the cost of transportation and handling of precast units in the site. Different percentages (0, 0.15, 0.30, and 0.45%) of volume fraction of barchip polypropylene (BPP) fibre have been incorporated to improve the mechanical properties of lightweight aggregate concrete (LWA) concrete. In this study, the mixture of crushed lightweight expanded clay aggregate (CLECA) and barchip polypropylene (BPP) fibre have been used to achieve compressive strength between 28 and 37 MPa at 28-days with an oven-dry density ranged between 1900 and 2000 kg/m3. It is found that the inclusion of BPP fibres at an optimum volume fraction concrete enhances the compressive strength, splitting tensile strength and modulus of rupture. The compressive strength of the lightweight aggregate concrete containing 0.45% volume fraction of BPP fibre (CLLWAC-BPP0.45%) had achieved the highest compressive strength of 37 MPa at 28-days with a significant increment of about 31% compared to plain concrete. Hence, the findings of this research showed that the development of eco-friendly lightweight structural composites can be used as an alternative solution for conventional lightweight concrete, infrastructure and marine fields application.

This research examined the performance of functionally graded two-stage fibrous concrete (FTSFC) against modified repeated falling-mass impacts. This study led to the concept of creating improved multiphysics model of fibre composites with better impact resistance for potential protective constructions. FTSFC was developed based on the bio-inspiring strength of turtle shells. The excellent impact resistance of FTSFC was accomplished by including a larger quantity of steel and polypropylene fibres in the outer layers. At the same time, one- and two-layered concrete were cast and compared to evaluate the efficiency of three-layered FTSFC. To minimize the dispersed test results, a modified form of the 544 drop-mass impact test was recommended by the American Concrete Institute (ACI). The modification was a knife-edge notched specimen instead of a solid cylindrical specimen without a notch. This modification predefined a crack path and reduced the dispersion of results. Cracking and failure impact numbers, ductility index, and failure mode were the testing criteria. The suggested modification to the ACI impact test decreased the coefficient of variance, showing that the dispersion of test results was reduced significantly. This study led to the concept of creating improved, fibre composites with better impact resistance for potential protective constructions.

The possibility of using geopolymer instead of Portland cement could effectively reduce carbon dioxide emissions from cement manufacturing. Fibre-reinforced self-compacting geopolymers have great potential in civil engineering applications, such as chord member grouting for concrete-filled steel tubular truss beams. However, to the best of the authors’ knowledge, the quantitative relationship between FF and the properties of the fibre-reinforced geopolymer has been rarely reported. In this research, 26 groups of mixtures were used to study the influence of the polypropylene fibre factor (FF) on the flowability and mechanical properties and also the compactness of the fibre-reinforced self-compacting geopolymer. At the same volume fraction, geopolymers with long fibres present worse flowability than those having short fibres due to the easier contacting of long fibres. By growing the FF the influence of fibre addition on the V-funnel flow rate is more significant than the slump spread. This can be ascribed to the consequence of fibre addition and friction by the V-funnel which estimates the restrained deformability. For FF lesser than critical factor Fc = 100, influence of fibres is negligible and fibres are far apart from each other and, thus, they cannot restrict cracking under load and transfer the load to improve the mechanical properties. For FF between the Fc = 100 and density factor Fd = 350, a noteworthy enhancement of mechanical properties was obtained and the geopolymer was still adequately workable to flow by weight of self, without any symbols of instability and fibre clumping. Under this condition, better fibre dispersal and reinforcing productivity can lead to better hardened properties. For FF higher than Fd = 350, fibres tend to come to be entwined together and form clumping resulting from the fibre balling, resulting in worse hardened properties. This research offers a sensible basis for the application of the workability regulator of the fresh properties of fibre-reinforced geopolymer as an operative way to basically obtain ideal mechanical properties.

Fibre or recycled material used in the concrete improves resistance, ductility, and durability of concrete. Concrete has fire-resistant properties but the most worrying thing about reinforced concrete structures during the fire is related to rebars. Therefore, there is a suggestion about use of alternative materials such as recycled metal spring in order to reduce above mentioned risks. In this paper, we conduct laboratory study to assess performance of concrete containing recycled metal spring while using volumetric amounts of 0.2, 0.4 and 0.6% at temperatures of 25, 100, 250, 500, 700 and 900 degrees Celsius. Furthermore, compressive strength and tensile strength of the most optimal combination of spring in the concrete are compared with concrete containing steel fibre and polypropylene. The results show that spring used in the concrete improves compressive strength and tensile strength. But the more the spring is used in the concrete, the more the resistance is reduced. Therefore, if the spring with 0.2 volume percent that is considered as the most optimal combination percentage is increased by 3 times, it increases compressive strength and tensile strength. Furthermore, the optimal compressive strength of spring in different temperatures is about 2 – 3 times of steel fibre and polypropylene and its tensile strength is close to strength of steel fibre. Fibre used in concrete reduces width of the cracks created after the test by 3 times.

Geopolymer offers significant promise to the construction world as a possible alternative to ordinary Portland cement (OPC). Like conventional Portland cement concrete, the matrix brittleness in geopolymer composites can be reduced by introducing suitable fibre reinforcement. A few investigations on fibre reinforced geopolymer composites are available. However there is still a gap to comprehend and enhance their performance. This paper describes the effect of incorporating micro polypropylene fibres on the strength and durability characteristics of geopolymer concrete. The engineering and durability properties like workability, compressive strength, split tensile strength, flexural strength, modulus of elasticity, and sorptivity of geopolymer concrete reinforced with micro polypropylene fibres is presented. The effect of the sulfuric acid attack on Geopolymer Concrete reinforced with micro polypropylene fibres is also discussed. The results show that hydrophobic characteristics of the micro polypropylene fibre led to weak contact with the geopolymer binder and hence weakened the mechanical performance of the fly ash based geopolymer matrix. However significant improvements in durability properties were noted.

A study has been made of mineral admixtures, such as ultra-fine Fly-ash and Metakoalin, and glass fibers and polypropylene fibers, to produce high performance Concrete. Glass fiber is maintained stable by volume by 0.25 percent by cement content in varying fractions (0.5 percent, 0.75 percent & 1.0 percent) and polypropylene fiber. SP 430 is applied to the concrete mix to ensure greater workability. The grade of concrete M70 is used. The cubes, cylinders and beams are casted for different water cement ratios of 0.275%, 0.30% and 1.00%. The strength tests are carried out for 14, 28 days and durability tests are carried for 56 days. The Behavior of the HPC specimens in compressive strength, flexure and splitting tensile strength were calculated. Due to the addition of mineral admixture & fiber volume into the mix, it gives very good performance & Suitable for construction.

Preplaced Aggregate Fibrous Concrete (PAFC) is a newly minted composite that has recently become more popular. The production of PAFC involves two essential processes, first, the fibres and coarse aggregate were filled into the empty framework to form the first layer of a natural skeleton, followed by grout injecting. A cement grout fills the voids in the first layer skeleton with slight compaction. This process is repeated to complete the remaining layers, hence, a type of Functionally-graded Preplaced Aggregate Fibrous Concrete (FPAFC) is obtained. The most recent studies revealed that the literature regarding the high-velocity projectile impact on fibrous concrete is well documented, however, the low-velocity repeated projectile impact on PAFC is still unexplored and needs particular emphasis. This research aims to investigate the FPAFC made with a new type of steel and polypropylene fibres against low-velocity projectile impact to fill this research gap. In the current study, twelve mixes were prepared with mono and hybrid combinations of fibres for pioneering the possible utilization of fibres in FPAFC. The maximum fibre dosage in this study is limited to 2.4%. The projectile impact resistance of FPAFC was assessed in line with penetration depth, front and rear damage surface area, weight loss, damage ratio and failure pattern. Additionally, a simplified analytical model was introduced to compute the ejected composite mass from the tested specimens. The results revealed that the addition of steel fibre in a single layer FPAFC exhibited an increasing compressive strength trend compared to the two/three-layered FPAFC. Furthermore, increasing the dosage of fibre at the bottom and top layers of FPAFC with a hybrid combination alleviates the spalling with an increasing number of impacts. The results from this research offer the reference information for more detailed research and studies of FPAFC under low-velocity projectile impact.

The objective of this paper is to analyse the mechanical behaviour of polypropylene fibre reinforced concrete subjected to load cycles and propose a model to predict the crack-opening increase and mechanical performance evolution over the cycles. Fatigue tests were performed in pre-cracked specimens with two fibre types and contents to assess the evolution of the crack-opening for prescribed numbers of load cycles. The residual flexural tensile strength was assessed before and after these tests to estimate the impact of the cycles in the remaining resistant capacity of the specimens. Results suggest that the mechanism of crack propagation is independent of the fibre type and content. The accumulated damage due to the cycles produces an offset in the quasi-static residual tensile strength curve. These findings underpin the proposal of a model to predict the evolution of the crack-opening and the remaining resistant capacity. An optimisation procedure is proposed to derive the model parameters using a limited number of initial load cycles. The first author thanks the Brazilian National Council for Scientific and Technological Development for the scholarship granted (233980/2014-8). This research was enabled by funds provided by the SAES project (BIA2016-78742-C2-1-R) of Spanish Ministerio de Economía, Industria y Competitividad. Likewise, this work was only possible thanks to the support from the Laboratory of Technology of Structures and Materials “Lluis Agulló" of Polytechnic University of Catalonia.

Ultra-high performance concretes (UHPC) are advanced cement-based materials characterised by superior mechanical properties with respect to normal and high-strength concretes; however, their dense and compact matrix can facilitate the onset of spalling at high temperatures. This problem is often coped up by adding polypropylene (PP) fibres to the mix design, alone or with other types of fibres; steel fibres enhance the material’s tensile capacity. The paper presents a series of tests on two UHPC types (150 and 180 N/mm2) with PP fibres (0.27% of volume) and variable content of steel fibres (0% to 1.92%), aimed at investigating the residual mechanical properties of the material after high temperature exposure. The experimental results are compared to available research on small UHPC specimens exposed to high temperatures, with dosages in PP fibres from 0.03% to 2%, and in steel fibres from 0 to 3%. The results of this research demonstrate that UHPCs need hybrid fibre reinforcement (PP + steel) to withstand high temperatures, and that the residual strength increases after 200 °C exposure, at all steel fibre dosages; this is in line with literature. Available research also shows that strength loss is possible in hot conditions, as found in the present research, while PP fibres alone do not always prevent the occurrence of spalling in small UHPC samples.

The heat-treated apricot shell can be utilized as coarse aggregates for producing sustainable bio-based lightweight concrete with good compressive strength but poor tensile strength. In order to improve the tensile properties of apricot shell concrete (ASC), the effects of polypropylene (PP) fibre, glass (G) fibre and basalt (B) fibre at various volume fractions (Vf) (0.25%, 0.5% and 0.75%) on the performance of ASC were investigated. The results indicated that the fibre type had no significant effect on the physical properties of ASC such as slump, density, water absorption and permeable porosity. However, the slump of ASC decreases with an increase in fibre content. The B fibre has a better improvement in mechanical properties than the PP fibre and G fibre thanks to the better elastic modulus and tensile strength. When the Vf was 0.5%, the compressive strength, splitting tensile strength, flexural strength and modulus of elasticity of ASC reinforced with B fibre were increased by 16.7%, 29.1%, 29.2%, and 18.1%, respectively, compared to ASC without any fibres. The magnesium sulfate attack results showed that the incorporation of the B fibre decreased the mass loss and compressive strength of ASC exposed to a MgSO4 solution for 6 months because the fibre arrested the microcracks caused by the expansive stress. It is concluded that the mechanical properties of bio-based ASC and its resistance to magnesium sulfate attack can be significantly improved by incorporating 0.5% B fibre.

Clayey soils endure adverse changes in strength and volume due to seasonal changes in moisture content and temperature. It has been well recognised that high cement content has been successfully employed in improving the mechanical properties of clayey soils for geotechnical infrastructural purposes. However, the environmental setbacks regarding the use of high cement content in soil reinforcement have necessitated the need for a greener soil reinforcement technique by incorporating industrial by-product materials and synthetic fibres with a reduced amount of cement content in soil-cement mixtures. Therefore, this study presents an experimental study to investigate the mechanical performance of polypropylene and glass fibre-reinforced cement-clay mixtures blended with ground granulated blast slag (GGBS), lime and micro silica for different mix compositions and curing conditions. The unconfined compressive strength, linear expansion and microstructural analysis of the reinforced soils have been studied. The results show that an increase in polypropylene and glass fibre contents caused an increase in unconfined compressive strength but brought on the reduction of linear expansion of the investigated clay from 7.92% to 0.2% at fibre content up to 0.8% for cement-clay mixture reinforced with 5% Portland cement (PC). The use of 0.4&ndash, 0.8% polypropylene and glass fibre contents in reinforcing cement-clay mixture at 5% cement content causes an increase in unconfined compressive strength (UCS) values above the minimum UCS target value according to American Society for Testing and Materials (ASTM) 4609 after 7 and 14 days curing at 20 &deg, C to 50 &deg, C temperature. Therefore, this new clean production of fibre-reinforced cement-clay mixture blended with industrial by-product materials has great potential for a wide range of applications in subgrade reinforcement.

The increasing need for eco-friendly green building and creative passive design technology in response to climatic change and global warming issues will continue. However, the need to preserve and sustain the natural environment is also crucial. A building envelope plays a pivotal role in areas where the greatest heat and energy loss often occur. Investment for the passive design aspect of building envelopes is essential to address CO2 emission. This research aims to explore the suitability of using integral-monolithic structural insulation fibre-reinforced lightweight aggregate concrete (LWAC) without additional insulation as a building envelope material in a high-rise residential building in the different climatic zones of the world. Polypropylene and steel fibres in different dosages were used in a structural grade expanded clay lightweight aggregate concrete. Physical and thermal properties of fibre reinforced structural LWAC, normal weight concrete (NWC) and bricks were measured in the lab. The Autodesk@Revit-GBS simulation program was implemented to simulate the energy consumption of a 29-storey residential building with shear wall structural system using the proposed fibre-reinforced LWAC materials. Results showed that energy savings between 3.2% and 14.8% were incurred in buildings using the fibre-reinforced LWAC across various climatic regions as compared with traditional NWC and sand-cement brick and clay brick walls. In conclusion, fibre-reinforced LWAC in hot-humid tropical and temperate Mediterranean climates meet the certified Green Building Index (GBI) requirements of less than 150 kW∙h∙m-2. However, in extreme climatic conditions of sub-arctic and hot semi-arid desert climates, a thicker wall or additional insulation is required to meet the certified green building requirements. Hence, the energy-saving measure is influenced largely by the use of fibre-reinforced LWAC as a building envelope material rather than because of building orientation.

This study investigates the fracture properties of high performance cementitious composites (HPCC) with four different types of fibres and with volume fraction content 3%. The four fibres are steel hooked end (S), polypropylene crimped (PP), basalt chopped (B), and glass (G) fibres. The tests were carried out in accordance with the RILEM recommendations. In order to examine the fresh properties of HPCC the slump flow tests were performed. Twelve fibre reinforced HPCC beam specimens with notch were cast and tested using central point loading experiments. In addition, experimental tests of the compressive strength and splitting tensile strength were carried out. The test results made it possible to obtain representative fracture parameters, such as the equivalent strengths, residual strengths, and fracture energy of fibre reinforced HPCC. The S fibre specimens showed the best performance in terms of workability, compressive strength, tensile splitting strength, and fracture energy at large deflection. On the other hand, G fibre specimens exhibited the best performance in terms of flexural strength, equivalent flexural strength at higher deflection, and residual flexural strength at lower deflection. In terms of equivalent flexural strength at lower deflection and residual flexural strength at higher deflection, basalt fibre specimens performed the best. On the contrary, polypropylene fibre reinforced beam specimens revealed the highest deflection capacity.

Fibre reinforced concrete (FRC) is recognized as suitable material for structural applications. The number of national codes that have approved it is an evidence. Structures where FRC is generally used can be subjected to fatigue loads and are expected to resist millions of cycles during their service life. Cyclic loads affect significantly the characteristics of materials and can cause fatigue failures. The most demanded cross-sections being cracked under tensile stresses due to direct loads or imposed deformations. Commonly, publications report fatigue behaviour of concrete under compression and are valid for uncracked sections. Imprecision in fatigue prescriptions are reflected through formulation of models that contemplate a probabilistic approach, or an introduction of high safety coefficients within construction codes. The aim of the present doctoral thesis is to perform a structural design oriented analysis on the behaviour of pre-cracked FRC subjected to flexural fatigue loads. FRC with steel and polypropylene fibre with different volume content were investigated by means of three-point bending tests, considering an initial crack width accepted in the service limit state. The mechanical behaviour of FRC were analysed in terms of applied load level, crack opening displacement (CMOD) and fatigue life. The residual flexural tensile strength was assessed after these tests to estimate the impact of the cycles in the remaining resistant capacity of the specimens. Results suggest that the mechanism of crack propagation is independent of the fibre type and content and the monotonic load-crack opening displacement curve might be used as deformation failure criterion for FRC under flexural fatigue loading. The conducted probabilistic approach allows predicting the fatigue strength of concrete reinforced with steel fibres. The findings postulate the proposal of a model to predict the evolution of the crack-opening and the remaining resistant capacity. An optimisation procedure is proposed to derive the model parameters using a limited number of initial load cycles. This doctoral thesis provides knowledge and data that may aid further research and contribute to the future development of design recommendations. El hormigón reforzado con fibra (FRC) se reconoce como material adecuado para aplicaciones estructurales. El número de normativas que lo han aprobado es una evidencia. Las estructuras donde generalmente se usa FRC pueden estar sujetas a cargas de fatiga y se espera que resistan millones de ciclos durante su vida útil. Las cargas cíclicas afectan significativamente a las características de los materiales y pueden causar roturas por fatiga. Las secciones transversales más demandadas se fisuran bajo tensión debido a cargas directas o deformaciones impuestas. Comúnmente, las publicaciones informan del comportamiento de fatiga del hormigón bajo compresión y son válidas para secciones no fisuradas. La imprecisión de las recomendaciones se refleja a través de la formulación de modelos que contemplan un enfoque probabilístico o la introducción de altos coeficientes de seguridad dentro de los códigos de construcción. El objetivo de la presente tesis doctoral es realizar un análisis orientado al diseño estructural sobre el comportamiento del FRC pre-fisurado sometido a cargas de fatiga por flexión. Se investigaron FRC con fibras de acero y polipropileno con diferentes contenidos de fibras mediante pruebas de flexotracción a tres puntos, considerando un ancho de fisura inicial aceptado en el estado límite de servicio. El comportamiento mecánico del FRC se analizó en términos de nivel de carga aplicada, desplazamiento de apertura de fisura (CMOD) y vida útil bajo fatiga. La resistencia residual a flexotracción se evaluó después de los ciclos de fatiga para estimar el impacto de los ciclos en la capacidad de resistencia restante de las muestras. Los resultados sugieren que el mecanismo de propagación de fisuras es independiente del tipo y contenido de fibra y la curva monotónica de CMOD podría ser utilizada como criterio de falla de deformación para FRC bajo carga de fatiga por flexotracción. El enfoque probabilístico realizado permite predecir la resistencia a la fatiga del hormigón reforzado con fibras de acero. Los resultados postulan la propuesta de un modelo para predecir la evolución de la apertura de fisura y la capacidad resistente remanente. Se propone un procedimiento de optimización para derivar los parámetros del modelo utilizando un número limitado de ciclos de carga inicial. Esta tesis doctoral proporciona conocimiento y datos que pueden ayudar a futuras investigaciones y contribuir al desarrollo futuro de recomendaciones de diseño.

Soil is the cheapest and easily available building material, but it is poor in mechanical properties such as bearing strength of soil. Research workers are continuously trying to improve the mechanical properties of soil, reinforced earth is a construction material having soil fill, toughen by addition of rods, bars, fibers, or nets that make a bond with the soil by mode of frictional resistance and act as a clear mass. It is used in many applications retaining structures, embankments etc. On comparing soil properties by adding different percentage of fibres by soil's dry weight by performing direct shear test and standard procter test different properties are carried out. As we add polypropylene fiber in the soil maximum dry density decreases and there is the increase in optimum moisture content direct shear test that performed on soil shows the decrement in the value of internal friction and increase in the value of cohesion. Increase in Unconfined compression strength Amjed Ali Khan | Er Anu "Enhanceing the Properties of Soil by using Synthetic Polypropylene" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-6 , October 2018, URL: https://www.ijtsrd.com/papers/ijtsrd18793.pdf

The impact resistance of functionally layered two-stage fibrous concrete (FLTSFC) prepared using the cement grout injection technique was examined in this study. The impact resistance of turtle shells served as the inspiration for the development of FLTSFC. Steel and polypropylene fibres are used in more significant quantities than usual in the outer layers of FLTSFC, resulting in significantly improved impact resistance. An experiment was carried out simultaneously to assess the efficacy of one-layered and two-layered concrete to assess the effectiveness of three-layered FLTSFC. When performing the drop-mass test ACI 544, a modified version of the impact test was suggested to reduce the scattered results. Instead of a solid cylindrical specimen with no notch, a line-notched specimen was used instead. This improvement allows for the pre-definition of a fracture route and the reduction of the scattering of results. The testing criteria used in the experiments were impact numbers associated to first crack and failure, mode of failure, and ductility index. The coefficient of variation of the ACI impact test was lowered due to the proposed change, indicating that the scattering of results was substantially reduced. This research contributes to the idea of developing enhanced, more impact-resistant fibre composites for use in possible protective structures in the future.

Melon is a little popular vegetable to grow in Poland, due to high climatic requirements. Ensuring appropriate thermal conditions for plants growth is possible with relatively late planting seedlings. However, late planting does not guarantee high yield of good quality fruit. The factor enabling the earlier planting seedlings and improving the conditions of growth is the use of flat covers. The field experiment was conducted in 2008–2010 in central-eastern Poland. The effect of planting seedlings of melon ‘Malaga F1’ (15 May, 25 May and 4 June) and the length of polypropylene fibre 17 g·m-2 covering (by 4 and 8 weeks from planting, until harvest, control without covering) on the yield and economic efficiency of melon cultivation in the field was investigated. Most preferably the yield level and profitability of melon cultivation were influenced by planting seedlings on the 15 May and covering by 4 weeks. However, earlier planting decreased the share of marketable fruits in the total number of fruits. The highest share in the costs structure of melon cultivation had the costs of human labour.

This paper aims to investigate the effect of the polypropylene fibre (PP) and basalt fibre (BF), singly or in hybridization, on the workability, mechanical, chloride resistance and pore structure characteristics of concrete. Sixteen mixtures consisting of PP and BF, both at volume content of 0.0, 0.1, 0.2 and 0.3%, were fabricated, and the slump, compressive, splitting tensile, flexural and charge passed were tested. The results show the hybridization of the PP and BF can improve three types of strength of concrete in comparison to their single fibre. Nevertheless, the hybridization is not always conducive, and the synergy of fibres is proposed and divided into positive and negative effects. The combination of the PP and BF both at content of 0.1% achieves the best mechanical performance, and is recommended for practical usage. Incorporating fibres reduces the chloride resistance of concrete, and the hybridization is helpless to this phenomenon, even the reduction is intensified at a highly hybrid fibre volume. However, increasing the curing age can mitigate this adverse effect caused by fibres. Furthermore, the microstructures were explored to elucidate the macro-properties of concrete in terms of interface and pore structure.

U ovom diplomskom radu ispitano je 15 različitih netkanih tekstila koji se razlikuju po sirovinskom sastavu (polipropilensko i poliestersko vlakno), površinskim masama (u rasponu od 97 g m-2 do 500 g m-2) te načinu učvršćenja (iglanje, iglanje i kalandriranje te učvršćenje termičkim putem uz pomoć vrućeg zraka). Svi uzorci su prošli sljedeće faze procesa izrade netkanog tekstila: pripreme vlakana, izrade runa na grebenaljci i polaganja na križnom polagaču. Nakon izrade runa dio uzoraka učvršćen je iglanjem, dio je učvršćen iglanjem i kalandriranjem, a dio je nakon grebenaljke i polaganja na križnom polagaču učvršćen termičkim putem prolaskom kroz vrući zrak. U radu su opisani proizvodni procesi i primarne karakteristike polipropilenskih i poliesterskih vlakana. Rezultati su prikazani u tablicama i grafikonima. Prekidna sila svih ispitanih netkanih tekstila veća je u smjeru suprotnom od izlaska materijala iz stroja (CMD). Veća prekidna sila u CMD smjeru karakteristična je za netkane tekstile proizvedene mehaničkim putem na grebenaljci te polaganjem runa na križnom polagaču. Uzorci učvršćeni termičkim postupkom imaju najmanju prekidnu silu. Uspoređujući netkane tekstile učvršćene iglanjem te s iglanjem i kalandriranjem vidljiv je utjecaj debljine na prekidnu silu, gdje povećanjem debljine netkanih tekstila prekidna sila raste. Prekidne sile uzoraka učvršćenih termičkim postupkom su najmanje. Zaključuje se da postupak učvršćenja i vrste sirovine značajno utječu na prekidnu silu netkanog tekstila dobivenog izradom runa mehaničkim putem., In graduation thesis 15 different nonwoven fabrics differing in raw material composition (polypropylene and polyester fibers), mass per unit area (ranging from 97 g/m-2 to 500 g/m-2) and method of bonding (needling, needling and calendaring and thermal bonding with the hot air) were tested. All samples passed through following process phases of nonwoven fabric production: fiber preparation, web making on card and laying on the cross-lapping machine. After web making, one part of the samples were bonded by needling, second part by needling and calendaring while third part were bonded by passing through hot air. In thesis production processes and primary characteristics of polypropylene and polyester fibers were described. The results are presented in tables and graphs. The breaking force of all tested samples is larger in the cross machine direction (CMD). The larger breaking force in the CMD direction is characteristic for nonwoven fabrics produced on the carding machine and by web laying on cross-lapping machine. Thermally bonded samples have the smallest breaking force. The influence of nonwoven fabric thickness bonded by needling process and by needling and calendaring on breaking force is noticeable, where by increasing the thickness of nonwovens, the breaking force increases. The breaking forces of the thermally bonded samples are the smallest. According to obtained results it can be concluded that bonding process and raw material significantly effect on the breaking force of nonwoven fabrics produced by carding machine.

The paper reports the results of experimental programme focused on the effect of various synthetic fibres on fracture properties and ductility of concrete. The fracture energy was assessed on beams with initial notches in three-point bend test. The incorporation of synthetic fibres had a slight effect on mechanical properties of concrete but, at the same time, it had a significant influence on the fracture energy by modification of post-cracking behaviour of concrete. It was found that the modern synthetic fibres might be able to impart significant toughness and ductility to concrete. However, the beneficial effect of fibres depends on their length and flexibility. The analysis of load-deflection curves obtained made it possible to fit the simple function, describing the post-peak behaviour of fibre reinforced concrete, which can be useful for the calculation of GF value.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.13246

Fracture mechanics is widely used to analyze the material behaviour in a structure. The paper reports the results of an experimental programme focused on the effect of various synthetic fibres on the fracture properties of concrete investigated in Mode I conditions. The changes in concrete properties were analysed on the basis of the critical stress intensity factor KIc, the critical value of crack tip opening displacement (CTODc) and the fracture energy GF. The addition of the synthetic fibres had a slight effect on the strength properties of concrete but, at the same time, it had a significant influence on the fracture mechanics parameters by the modification of pre-cracking and particularly post-cracking behaviour of the concrete. Results of measuring the toughness and energy-absorption characteristics showed that the specimens reinforced with synthetic fibres acquired a great ductile behaviour and energy absorption capacity, compared to ordinary concrete specimens.

Highway transportation is the most preferred transportation system as compared to other modes due to its high accessibility. Flexible highway pavement consists of mainly aggregate and bitumen, besides, in order to improve performance, some organic and/or inorganic additives are also utilized as additional constituents in the hot mix asphalt (HMA). By improving performance, positive characteristics can be gained to the HMA such as high strength, durability, toughness, suitable flexibility and resistance to impact. In this study, an attempt has been made to minimize deterioration due to the damage given by different aggressive environmental conditions. For that purpose, polypropylene fibers were added in varying ratios (0, 5, 7.5 and 10% by weight of binder) into the HMA, then these mixtures were maintained in the freeze-thaw cycling cabinet, CaCl 2 , NaCl and Na 2 SO 4 solutions for a certain period. The results showed that stability increased continuously by mixtures with a content of up to 7.5% of polypropylene fibre, and then a drop was observed by 10% fibre reinforced mixtures. In addition, exposure to freeze-thaw cycles and Na 2 SO 4 solution was found as the most harmless and harmful conditions, respectively among other environments in the investigation.

The article presents the results of research work aimed at testing the use of hybrid steel-polypropylene fibre as a strengthening solution to upgrade reinforced high-performance concrete (HPC) beams with openings (BO1 &divide, BO3) and without (B1 &divide, B3). A total of six simply supported beams were tested under four-point bending. The test beams had a cross section of 200 &times, 400 mm and a total length of 2500 mm. Two square openings in each shear span were located symmetrically about the mid-point in three BO beams. Research was carried out with regard to the quantity and type of reinforcement. Beams B1 and BO1 were constructed with traditional reinforcement made of steel bars. As regards the remaining beams, instead of stirrups and compressive bars, fibre reinforcement of varying fibre volume contents was applied. In the analysis, a non-contact system for three-dimensional measurements of strain and displacement was used. Analysis of the behaviour of the beams under static load was based on the measurements of cracks, deflections and strains. The test results show that the first diagonal crack and the ultimate shear strength increase significantly as the fibre content increases. The above study showed that the hybrid fibres have a positive effect, reducing crack width and ensuring an increase in the load-bearing capacity.

The main intention of the present experimental case is to study the fallout of Silica Fume restoration on Durability properties. Effect of combined application of polypropylene fibre and silica fume on water absorption test (Durability Test). Dosage of Silica Fume is 5%, 10% and 15% by the weight of cement. Dosage of Polypropylene Fibre used are 0.25%, 0.5% of the total weight of the Cube. Water absorption test on the cubes was done for 28 days. It is observed that Water Absorption for the Control Concrete is 4.21%. The Water Absorption for the Concrete with Silica Fume and Polypropylene Fiber is minimum when correlated to Control Concrete. Least percentage in Gain of Weight is 2.97% for Concrete with 10% Silica Fume and 0.5% Polypropylene Fiber. https://journalnx.com/journal-article/20150462

The current version of the European standard for concrete structures gives tabulated data for the evolution of the mechanical properties of normal strength concrete subjected to elevated temperatures. However, the standard acknowledges the lack of sufficient data for the case of high strength concrete with limestone aggregate and there are no provisions for fibre reinforced concrete at high temperatures. This paper presents the experimental results obtained on six batches of normal and high strength fibre reinforced concrete made with limestone aggregates and tested after exposure to high temperatures. These results gave a good correlation with previous researches and equations were obtained to describe the evolution of the compressive strength and the flexural strength at elevated temperatures. Ductility was also measured in the flexural strength tests and results suggested that the use of steel fibres with higher aspect ratio may lead to lower ductility after exposure to temperatures higher than 650 °C.

The present research work has been carried out to evaluate the feasibility of utilization of coal bottom ash as fine aggregate in concrete and Polypropylene fibre is additionally used to enhance the strength characteristics of concrete. The concrete mix of M25 grade is prepared for different combinations of 0%, 10%, 20% and 30% of replacement of sand by bottom ash with 0.5%, 1.0%, 1.5% polypropylene fibre by total weight of taken Cube. The durability properties of concrete after 28days of curing age are tested. https://journalnx.com/journal-article/20150397

In this thesis, the research of criteria is regarding the concept of investigation of residual strengths of polypropylene and steel reinforced concrete. Six samples of polypropylene reinforced concrete samples were tested using three-point bending test and is compared against reference samples of steel fibre reinforced concrete for various parameters like displacement and crack width opening. The crack width opening is calculated for polypropylene samples under different readings and is compared with steel samples. It is found that steel fibre reinforced concrete samples is known to have a higher residual strength when compared against polypropylene samples. Steel fibre reinforces concrete samples also have a higher tolerating capacity when a heavy load is applies against them, Pluoštu armuoto betono (FRC) yra sustiprintas betono mišinys su paskirstyta atsitiktiniais mažų fragmentų pluoštais. Į FRC, iš mažyčių skaidulų pasiskirsto atsitiktinai betono maišymo metu, ir taip pagerina konkrečias savybės tam tikromis kryptimis. Pluoštai lengviau perduoda apkrovą esant mažiems plyšiams. FRC yra fibromis armuotas betonas, kuris buvo sukurtas per pastaruosius metus. Dabar jis yra sėkmingai naudojamas statyboje su savo geru lenkimotempimo stipriu, atsparumas smūgiams ir geru pralaidumu ir atsparumu šalčiui ir įvairius kitus veiksnius, kurie padeda užtikrinti ilgą pastato kokybę. Ši darbas remiasi šio pluošto tyrimu, tyrime buvo naudojami dviejų skirtingų rūšių pluoštai, studijuoti likutinį betono stiprį, naudojant polipropileno ir plieninės skaidulas. Šeši bandiniai buvo pagaminti polipropileno pluošto ir išbandyti naudojant tritaškį lenkimo bandymą, gauti rezultatų yra palyginami su plieno pluošto gautais rezultatai iš literatūros. Nustatyta, kad plienas yra didesnio liekamojo stipri, palyginti su polipropileno.

The article presents the crack and deflection states analysis of the reinforced deep beams with openings made of high performance steel and polypropylene fibre concrete. Research was carried out with regard to quantity and the type of reinforcement. The deep beam T1 was constructed conventionally with steel rods reinforcement. As regards deep beams T2 and T3, instead of the steel wire mesh, fibre reinforcement of variable fibre volume percentage was applied. The analysis of the behaviour of the deep beams under static load was based on the measurements of cracks and deflections.[b]Keywords[/b]: reinforced concrete deep beams with openings, high performance concrete, steel fibre, polypropylene fibre, crack state, deflections

The article presents the crack and strain states analysis of the reinforced high performance concrete beams with steel and polypropylene fibre. The beams were bent in the 4-point model. Research was carried out for three different beams with regard to the quantity and the type of reinforcement. The beam B1 was constructed conventionally with steel rods reinforcement. As regards beams B2 and B3, instead of the stirrups and the compressive rods, fibre reinforcement of variable fibre volume percentage was applied. For the analysis, a non-contact system for three-dimensional measurements of strain – ARAMIS was used. The analysis of the behaviour of the beams under static load was based on the measurements of crack and strain.[b]Keywords[/b]: reinforced concrete beams, high performance concrete, steel fibre, polypropylene fibre, ARAMIS system, crack state, strain state

The article presents the crack and strain states analysis of the reinforced high performance concrete beams with steel and polypropylene fibre. The beams were bent in the 4-point model. Research was carried out for three different beams with regard to the quantity and the type of reinforcement. The beam B1 was constructed conventionally with steel rods reinforcement. As regards beams B2 and B3, instead of the stirrups and the compressive rods, fibre reinforcement of variable fibre volume percentage was applied. For the analysis, a non-contact system for three-dimensional measurements of strain – ARAMIS was used. The analysis of the behaviour of the beams under static load was based on the measurements of crack and strain.[b]Keywords[/b]: reinforced concrete beams, high performance concrete, steel fibre, polypropylene fibre, ARAMIS system, crack state, strain state

An investigation was done on the effect of different types of organic mulches that were applied in form of straw to the soil mulching process, on the weed infestation, number, and fresh mass of weeds in broccoli cv. Milady F1 (Brassica oleracea L. var. italica Plenck) and tomato cv. Polfast F1 (Lycopersicon esculentum Mill.) grown under polypropylene fibre as a covering, or grown without a covering. The different types of organic straw mulches were: rye (Secale cereale L.), corn (Zea mays L.), rape (Brassica napus L. subsp. napus), and buckwheat (Fagopyrum esculentum Moench.). All the organic mulches were applied at a dose of 10 t/ha. The effect of the mulches was compared to a control plot which had no mulch. The type of organic mulch applied to the soil mulching process influenced species composition, number, and fresh mass of weeds. This effect could be the result of the properties of the mulch (colour, structure, etc.) or the allelopathic effect on the germination and growth of individual weeds species. Irrespective of the investigated factors, 24 and 25 weeds species, respectively, were observed immediately after cover removal and before broccoli and tomato harvest. In the first date of estimation Chenopodium album L., Echinochloa crus-galli (L.) P. Beauv., Fallopia convolvulus (L.) Á. Löve, Stellaria media (L.) Vill., and Viola tricolor L. dominated, however, before the vegetables were harvested Ch. album, V. tricolor, Veronica arvensis L., and E. crus-galli dominated. An application of polypropylene fibre contributed to an increase in the number and fresh mass of weeds in both vegetables in the first date of estimation (after cover removal). During this period, vegetables cannot compete with weeds. It is important to note, though, that before the vegetables were harvested, a decrease was found in the number and fresh mass of weeds in the covered plots. The most efficient weed limiter, both after cover removal and also before the broccoli and tomatoes were harvested, was buckwheat and rye straw, respectively.

This experimental study investigates the effect of specimen shape on residual mechanical properties of polypropylene (PP) fibre self-compacting concrete (SCC) exposed to elevated temperatures from 200 to 600 °C. Various shaping regimes were used including cylindrical and cubical shapes for a series of durations of 2 and 4 h, and air cooling to the room temperature before testing. The temperature determination results prove that the shaping regimes caused an action of “thermal shock” to SCC under elevated temperatures, characterized by a high temperature at fixed time of exposure. The experimental results indicate that, compared cylindrical specimen with cubical one, thermal shock induced by cylindrical shape air cooling caused more severe damage to concrete in terms of greater losses in compressive strength than those with cubical shapes. The fact that the impact of shapes on mechanical properties indicates that shaping could cause thermal shock to specimens, which is in good agreement with the results of the temperature determination. PP fibre can enhance residual strength and fracture energy of concrete subjected to thermal shock induced by air cooling from high temperatures up to 600 °C to room temperature.

A comprehensive program of experiments consisting of compression, uniaxial compression, direct shear, flexural as well as splitting tensile and air permeability tests were performed to analyse the effect of the level of fibre dosage and the water&ndash, cement ratio on the physical properties of hybrid fibre-reinforced concrete (HFRC). Two types of fibres were studied in terms of their effect on the properties of HFRC. The results indicated that the mechanical properties of concrete were significantly improved by increasing the fibre content. However, increasing the percentage fibre content past a certain peak performance limit (0.9% glass fibre (GF) and 0.45% polypropylene fibre (PPF)) led to a decrease in strength compared to reference mixes. Additionally, the incorporation of hybrid fibres yielded an increase in air permeability in the tested specimens. The results showed that the strength-related properties of HFRC were superior to the properties of single fibre-reinforced concrete.

Explosive spalling consists in the sudden separation of concrete layers or pieces from the surface exposed to fire, due to (a) stress caused by thermal gradients and external loads and (b) pore pressure rise induced by water vaporization. As regards the material properties, the phenomenon is affected by some meso- and micro-structural aspects mainly concerning the interaction during heating among cement paste, aggregate and fibre, thus influencing porosity and permeability variation at high temperature. Focusing on the effect of pore pressure in fracture behaviour of Normal-Strength and High-Performance Concretes, an experimental campaign has been planned, aimed at investigating the role played by the mix design. Nine concrete mixes have been studied considering three grades (fc ≥ 40, 60 and 90 MPa), three aggregate types (silico-calcareous, basalt and calcareous aggregates) and different fibre types and contents (monofilament or fibrillated polypropylene fibres). The experimental study, based on indirect tension tests performed under different levels of sustained pore pressure, clearly shows that the influence of pressure on concrete fracture response during heating strongly depends on mix design.

This study has investigated the changes that might appear in post-peak flexural response. Before the flexural test, prismatic specimens were placed in a furnace chamber and exposed to elevated temperatures of 400, 600, and 800 &deg, C. The flexural toughness test was carried out on two types of concrete: Plain ultra-high performance concrete (UHPC) and UHPC with different types of fibres (steel fibre (SF) and polypropylene fibre (PPF)) at 0.5%, 1%, 1.5%, and 2% volume fractions. During the flexural test in the macro-crack development analysis, the non-contact ARAMIS system was used to perform three-dimensional measurements of strain and displacement. The results of scanning electron microscope (SEM) observations of micro-crack development in UHPC without and with SF/PPF were also presented. The experimental results showed that in some cases, the load&ndash, deflection curve of fibre-reinforced UHPC displayed a double-peak response. The first peak signified the UHPC properties, while the second peak represented the properties of the fibres. Under flexural load, the toughness decreased as the temperature increased. Significant decrease in the load&ndash, deflection response and toughness were observed for the polypropylene fibre-reinforced UHPC when the temperature approached 800 &deg, C. The SEM observation results showed that the thermal damage of fibre-reinforced UHPC depends on the pore pressure effect, the thermal mismatch, the decomposition of hydration products, and the formation of micro-cracks.

The article presents the results of research and analysis of reinforced high performance concrete beams with steel and polypropylene fibres at service load. The beams were bent in the 4-point model. Research was carried out for three different rectangular reinforced concrete beams in terms of the quantity and the type of reinforcement. The beam B1 was constructed conventionally with reinforced steel rods. The beams B2 and B3, instead of the compressive rods and the stirrups the fibre reinforcement of variable fibre volume percentage was applied. In the tests a non-contact system for three-dimensional measurements of deformation – ARAMIS was used. The analysis of the behaviour of the beams under static load for serviceability was based on: images of cracks, strain and force – displacement curves.

ABSTRACT: The objective of this study was to examine the influence of discrete and randomly distributed fibres on heave of an expansive soil. One-dimensional swell tests were conducted on a remoulded expansive soil with and without fibres. In this study, fibre content was varied as 0.25 and 0.5% and fibre length as 30, 60 and 90 mm. A twin semi-circular-shaped fabricated mould with a front Perspex sheet was developed for testing. Digital imaging technique was used to observe heave of the soil in both unreinforced and fibre-reinforced conditions. Displacement profiles obtained from image analysis were used for interpreting swell or upward movement profiles of the specimens. Heave observed in the digital image analysis was compared with that obtained from dial gauge readings. Reduction in heave was directly proportional to fibre content and fibre length. Reduction in heave was the maximum at low aspect ratios at both fibre contents of 0.25 and 0.5%. Test results revealed that fibre length is a key factor that influences the reinforcing effect of fibre. Discrete and randomly distributed fibres were found efficacious in reducing heave.

Environmental and structural loads cause stresses, deformations, and displacements in structures. According to the building codes, they have to be designed and built to safety resist all those actions during entire service life. When deteriorated, structures must be repaired and strengthen so that during usage they do not represent a risk for the users. Due to the low expenses and good mechanical characteristics, cement-based composites are often used for repairs. In structures susceptible to shrinkage and/or exposed to specific load conditions, used cement-based composites are improved with polypropylene fibres. These composites have many beneficial characteristics ; like as reduced occurrence of microcracks, positive effect on autogenous, plastic and restrained shrinkage, increased resistance to spalling during the fire, accessible price etc. Due to those characteristics, they are often used for repair of slabs, pavements and concrete overlays. Detailed state-of-the-art is presented and encompasses both fresh and hardened state properties. Also, a possibility for further improvement of repair materials is discussed.

This paper presents the experiment results of investigating the effects of adding various types and proportions of fibre on mechanical strength and permeability characteristics of recycled aggregate concrete (RAC), which was produced with treated coarse recycled concrete aggregate (RCA). Two types of synthetic fibres (i.e., barchip and polypropylene fibre) with various volume fractions were added to the RAC, which was calculated by the weight of the cement. The hardened RAC properties such as compressive strength, flexural strength, ultrasonic pulse velocity, water absorption and total porosity at the curing ages of 7 and 28 days were evaluated and compared with the properties of the control specimens. Results indicate that the treated coarse RCA enhances the mechanical strength and permeability properties of RAC and adding barchip fibre further optimises the results. Adding 1.2% barchip fibre has the best effect on the mechanical strength performance of the RAC., {"references":["S. 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