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Signorini, Cesare. "Durable and Highly Dissipative Fibrous Composites for Strengthening Coastal Military Constructions". Key Engineering Materials 893 (20.07.2021): 75–83. http://dx.doi.org/10.4028/www.scientific.net/kem.893.75.
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Reinforced concrete strategic structures for military purposes are often established in coastalor offshore areas, widely subjected to chemical attacks, mainly due to an aggressive saline and acidenvironments. Porosity of cementitious conglomerates favour penetration of chlorides, which tend tocorrode the internal metallic rebar. The reinforcement of structures with fibrous composite materialsis a viable solution to restore the initial requirements of the building, especially when it exerts defence purposes. Among synthetic fibres, polyphenylenebenzobisoxazole (PBO) is an organic fibre based on linked aromatic structures with high elastic modulus and tensile strength and highly dissipative attitudes. In this work, the assessment of durability of continuous fibrereinforced cementitious mortar (FRCM) composites is carried out comparing the mechanical performance of laminates subjected to uniaxial tensile tests. It is found that PBOFRCM presents high resistance against aggressive environments and specifically preserve its mechanical strength in the presence of saltwater, where other reinforcing materials undergo to a dramatic degradation process.
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Murali, G., Sallal R. Abid, Hakim S. Abdelgader, Y. H. Mugahed Amran, Mohammad Shekarchi i Krzysztof Wilde. "Repeated Projectile Impact Tests on Multi-Layered Fibrous Cementitious Composites". International Journal of Civil Engineering 19, nr 6 (9.01.2021): 635–51. http://dx.doi.org/10.1007/s40999-020-00595-4.
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Dutkiewicz, Maciej, Hasan Erhan Yücel i Fatih Yıldızhan. "Evaluation of the Performance of Different Types of Fibrous Concretes Produced by Using Wollastonite". Materials 15, nr 19 (5.10.2022): 6904. http://dx.doi.org/10.3390/ma15196904.
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Production of cement and aggregate used in cement-based composites causes many environmental and energy problems. Decreasing the usage of cement and aggregate is a crucial and currently relevant challenge to provide sustainability. Inert materials can also be used instead of cement and aggregates, similar to pozzolanic materials, and they have positive effects on cement-based composites. One of the inert materials used in cement-based composites is wollastonite (calcium metasilicate-CaSiO3), which has been investigated and attracted attention of many researchers. This article presents state-of-the-art research regarding fibrous concretes produced with wollastonite, such as mortars, conventional concrete, engineered cementitious composites, geopolymer concrete, self-compacting concrete, ultra-high-performance concrete and pavement concrete. The use of synthetic wollastonite, which is a novel issue, its high aspect ratio and allowing the use of waste material are also evaluated. Studies in the literature show that the use of wollastonite in different types of concrete improves performance properties, such as mechanical/durability properties, and provides environmental–economic efficiency. It has been proven by studies that wollastonite is a material with an inert structure, and, therefore, its behavior is similar to that of a fiber in cementitious composites due to its acicular particle structure.
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Sreenath, Sreekumaran, Kaliyaperumal Saravana Raja Mohan i Gunasekaran Murali. "Fracture Toughness of Reactive Powder Fibrous Concrete Composites under Pure and Mixed Modes (I/III)". Buildings 12, nr 5 (5.05.2022): 599. http://dx.doi.org/10.3390/buildings12050599.
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Reactive Powder Concretes (RPC) are well known for their exceptional strength properties and durability properties. The use of Supplementary Cementitious Materials (SCM) is the best way to enhance the strength and durability characteristics of RPCs further. Among various SCMs, the potential of Ground Granulated Blast-furnace Slag (GGBS) is proven by many researchers. However, the effect of GGBS on the fracture toughness of RPCs, especially under the tearing mode, is not explored. This study investigates the effect of partial replacement of OPC with GGBS in non-fibrous and fibrous RPCs, on its mode I (pure opening), mode III (pure tearing), and mixed-mode I/III fracture behaviour. A significant improvement in mode I, mode III, and mixed-mode I/III fracture toughness was observed due to incorporating GGBS and fibres in RPCs. The fibrous mix with 30% OPC, replaced with GGBS, exhibited the highest values of mode I and mode III fracture toughnesses, which were 2.35 MPa·m0.5 and 0.98 MPa·m0.5, respectively, and significantly high compared to the control non-fibrous and fibrous RPC mixes. The study reveals the ability of GGBS as an SCM to improve the fracture toughness of RPC mixes, thereby delaying the failure of the process of structural components.
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Lancellotti, Isabella, Federica Piccolo, Hoang Nguyen, Mohammad Mastali, Mohammad Alzeer, Mirja Illikainen i Cristina Leonelli. "The Effect of Fibrous Reinforcement on the Polycondensation Degree of Slag-Based Alkali Activated Composites". Polymers 13, nr 16 (10.08.2021): 2664. http://dx.doi.org/10.3390/polym13162664.
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Alternative cementitious binders, based on industrial side streams, characterized by a low carbon footprint, are profitably proposed to partially replace Portland cement. Among these alternatives, alkali-activated materials have attracted attention as a promising cementitious binder. In this paper, the chemical stability of the matrix, in fiber-reinforced slag-based alkali-activated composites, was studied, in order to assess any possible effect of the presence of the reinforcement on the chemistry of polycondensation. For this purpose, organic fiber, cellulose, and an inorganic fiber, basalt, were chosen, showing a different behavior in the alkaline media that was used to activate the slag fine powders. The novelty of the paper is the study of consolidation by means of chemical measurements, more than from the mechanical point of view. The evaluation of the chemical behavior of the starting slag in NaOH, indeed, was preparatory to the understanding of the consolidation degree in the alkali-activated composites. The reactivity of alkali-activated composites was studied in water (integrity test, normed leaching test, pH and ionic conductivity), and acids (leaching in acetic acid and HCl attack). The presence of fibers does not favor nor hinder the geopolymerization process, even if an increase in the ionic conductivity in samples containing fibers leads to the hypothesis that samples with fibers are less consolidated, or that fiber dissolution contributes to the conductivity values. The amorphous fraction was enriched in silicon after HCl attack, but the structure was not completely dissolved, and the presence of an amorphous phase is confirmed (C–S–H gel). Basalt fibers partly dissolved in the alkaline environment, leading to the formation of a C–N–A–S–H gel surrounding the fibers. In contrast, cellulose fiber remained stable in both acidic and alkaline conditions.
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Querido, Victor A., José Roberto M. d’Almeida i Flávio A. Silva. "Development and analysis of sponge gourd (Luffa cylindrica L.) fiber-reinforced cement composites". BioResources 14, nr 4 (31.10.2019): 9981–93. http://dx.doi.org/10.15376/biores.14.4.9981-9993.
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Sponge gourd (Luffa cylindrica L.) fiber-reinforced cement composites were developed and analyzed. Dried sponge gourd fruit’s fibrous vascular system forms a natural 3D network that can reinforce matrices in composite materials, diverting cracks along the complex array of 3D interfaces between the fibers and the cementitious matrix. To avoid fiber deterioration, the cement paste was modified by incorporating pozzolanic materials. The fibers were mechanically characterized by tensile testing of strips of the 3D natural fiber array and of single fibers extracted from the array. The fibers had an average tensile strength of 140 MPa and an average Young’s modulus up to 28 GPa. Image analysis showed that the fiber spatial distribution inside the 3D network was random. The modified cement paste was characterized by its workability (flow table test) and mechanical behavior (compression and three-point bending tests), with average results of 430 mm, 62.7 MPa, and 6.2 MPa, respectively. Under bending, the cement matrix collapsed after the first crack. The sponge gourd-cement composite manufactured with 1 wt% of fibers showed an average flexural strength of 9.2 MPa (approximately 50% greater than the unreinforced matrix). Importantly, the composite also presented a limited deflection-hardening behavior. These results support sponge gourd’s possible use as reinforcement in cement matrix composites.
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Malchiodi, Beatrice, Erika Iveth Cedillo-González, Cristina Siligardi i Paolo Pozzi. "A Practical Valorization Approach for Mitigating Textile Fibrous Microplastics in the Environment: Collection of Textile-Processing Waste Microfibers and Direct Reuse in Green Thermal-Insulating and Mechanical-Performing Composite Construction Materials". Microplastics 1, nr 3 (22.07.2022): 393–405. http://dx.doi.org/10.3390/microplastics1030029.
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Microplastic (MP) contamination is an urgent environmental issue to address. Fibrous microplastics (FMPs) are the principal MP type in the air and have already been found in human stool and lung tissues. FMPs are generated from the lifecycle of synthetic and blended textiles and are expected to increase due to fast fashion. Among textile processes, the finishing of fabrics is estimated to generate 5000 t/year of textile waste fibers in Italy, including FMPs. To limit FMPs spread, this paper suggests, for the first time, the direct collection of blended finishing textile waste microfibers and reuse in designing thermal-insulating and mechanical-performing fiber-reinforced cementitious composites (FRCs). The microfibers were thoroughly characterized (size, morphology, composition, and density), and their use in FRCs was additionally evaluated by considering water absorption and release capacity. Untreated, water-saturated, and NaOH-treated microfibers were considered in FRCs up to 4 wt%. Up to a +320% maximum bending load, +715% toughness, −80% linear shrinkage, and double-insulating power of Portland cement were observed by increasing microfiber contents. NaOH-treated and water-saturated microfibers better enhanced toughness and linear shrinkage reduction. Therefore, green and performant composite construction materials were obtained, allowing for the mitigation of more than 4 kg FMPs per ton of cement paste. This is a great result considering the FMP contamination (i.e., 2–8 kg/day fallout in Paris), and that FRCs are promising and shortly-widely used construction materials.
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Rizzo, Valeria, Antonio Bonati, Francesco Micelli, Marianovella Leone i Maria Antonietta Aiello. "Influence of Alkaline Environments on the Mechanical Properties of FRCM/CRM and their Materials". Key Engineering Materials 817 (sierpień 2019): 195–201. http://dx.doi.org/10.4028/www.scientific.net/kem.817.195.
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Fabric Reinforced Mortar (FRCM) used as Externally Bonded Reinforcements (EBR), provide a sustainable solution for retrofitting and repair of existing masonry structures. They are commonly made by fibrous meshes embedded in a cementitious/hydraulic lime matrix. This technique represents a valid alternative to the well-known FRP (Fiber Reinforced Polymer) composites, which show some limitations in heritage masonry applications. In this scenario, a new system known as CRM (Composite Reinforced Mortar) has been developed in the last years. In this system, a pre-cured FRP grid is utilized as internal reinforcement in a mortar layer. The system reproduces the traditional technique of reinforced plaster, where the steel grid is substituted by a non-metallic one. In masonry applications high compatibility with the substrate, sustainability and removability are commonly required in heritage construction. These goals are not easily achieved by using fibers immersed into a polymeric resin. Moreover, the inorganic matrix ensures the transpiration of substrates and consequently a higher durability of the whole strengthened system is expected. On the other hand, the recent use of these new materials in civil engineering needs appropriate design guidelines. The proposed paper focuses attention on the initial results of a large experimental study on the durability of FRCM/CRM systems and their single components (dry glass fibers, resin, pre-cured FRP grid and mortar). In particular, the influence of three alkaline environments solutions was studied. Exposure conditions were stressed by increasing the temperature of the three aqueous solutions. The mechanical retention of tensile properties was measured by performing direct tensile tests after different exposure times.
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Adamu, Musa, Yasser E. Ibrahim i Hani Alanazi. "Evaluating the Influence of Elevated Temperature on Compressive Strength of Date-Palm-Fiber-Reinforced Concrete Using Response Surface Methodology". Materials 15, nr 22 (16.11.2022): 8129. http://dx.doi.org/10.3390/ma15228129.
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Due to its availability and affordable processing, date palm fiber (DPF) is among the natural and sustainable fibers used in cementitious composites. Furthermore, DPF is an agricultural, organic, and fibrous material that when subjected to higher temperature can easily degrade and cause reduction in strength. Therefore, the influence of elevated temperatures on the unit weight and strengths of DPF-reinforced concrete needs to be examined. Under this investigation, DPF is used in proportions of 0–3% weight of binder to produce a DPF-reinforced concrete. Silica fume was utilized as a supplemental cementitious material (SCM) in various amounts of 0%, 5%, 10%, and 15% by weight to enhance the heat resistance of the DPF-reinforced concrete. The concrete was then heated to various elevated temperatures for an hour at 200 °C, 400 °C, 600 °C, and 800 °C. After being exposed to high temperatures, the weight loss and the compressive and relative strengths were examined. The weight loss of DPF-reinforced concrete escalated with increments in temperature and DPF content. The compressive and relative strengths of the concrete improved when heated up to 400 °C, irrespective of the DPF and silica fume contents. The heat resistance of the concrete was enhanced with the replacement of up to 10% cement with silica fume when heated to a temperature up to 400 °C, where there were enhancements in compressive and relative strengths. However, at 800 °C, silica fume caused a significant decline in strength. The developed models for predicting the weight loss and the compressive and relative strengths of the DPF-reinforced concrete under high temperature using RSM have a very high degree of correlation and predictability. The models were said to have an average error of less than 6% when validated experimentally. The optimum DPF-reinforced concrete mix under high temperature was achieved by adding 1% DPF by weight of binder materials, replacing 12.14% of the cement using silica fume, and subjecting the concrete to a temperature of 317 °C. The optimization result has a very high desirability of 91.3%.
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Abbas, Al-Ghazali Noor, Farah Nora Aznieta Abdul Aziz, Khalina Abdan, Noor Azline Mohd Nasir i Mohd Nurazzi Norizan. "Kenaf Fibre Reinforced Cementitious Composites". Fibers 10, nr 1 (4.01.2022): 3. http://dx.doi.org/10.3390/fib10010003.
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Increased environmental awareness and the demand for sustainable materials have promoted the use of more renewable and eco-friendly resources like natural fibre as reinforcement in the building industry. Among various types of natural fibres, kenaf has been widely planted in the past few years, however, it hasn’t been extensively used as a construction material. Kenaf bast fibre is a high tensile strength fibre, lightweight and cost-effective, offering a potential alternative for reinforcement in construction applications. To encourage its use, it’s essential to understand how kenaf fibre’s properties affect the performance of cement-based composites. Hence, the effects of KF on the properties of cementitious composites in the fresh and hardened states have been discussed. The current state-of-art of Kenaf Fibre Reinforced Cement Composite (KFRCC) and its different applications are presented for the reader to explore. This review confirmed the improvement of tensile and flexural strengths of cementitious composites with the inclusion of the appropriate content and length of kenaf fibres. However, more studies are necessary to understand the overall impact of kenaf fibres on the compressive strength and durability properties of cementitious composites.
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Zhang, Lin, Fu Sheng Liu, Ji Yong Song, Yan Bin Zhang i Gang Gang Dong. "Mechanical Strength and Microstructure Analysis of Cementitious Wheat Straw Composite". Applied Mechanics and Materials 357-360 (sierpień 2013): 766–72. http://dx.doi.org/10.4028/www.scientific.net/amm.357-360.766.
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Wheat straw alkali treatment has impacts on the strength of cement mortar and glazed hollow beads insulation mortar. The results show that the bending strength and bending strength of cement mortar specimen with 4% wheat straw are respectively 58.3% and 40.9% of the benchmark specimen, but bending-press ratio of the latter is 1.42 times of the former. The SEM images reflect the straws influences on the cement hydrate morphology, status and the influence of the number on cement mortar and glazed hollow beads insulation mortar. Compared with the latter, the former C-S-H gel is loose fibrous, failure to form a good network. In the thermal insulation mortar consistency and stratification of the same circumstances, with straw dosage increased, strength first increases, then declining. And folding pressure than in straw dosage is less than 24% more ideal. The SEM pictures show that network C-S-H gel decrease and loose fibrous C-S-H gel increased. At the same time, AFt gradually become attenuate and curly.
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dos Santos, Renan Felinto, Fernando Ribeiro Oliveira, Marcio Roberto da Rocha, Rafael Aguilar Velez i Fernanda Steffens. "Reinforced cementitious composite using viscose rayon fiber from textile industry waste". Journal of Engineered Fibers and Fabrics 17 (styczeń 2022): 155892502211157. http://dx.doi.org/10.1177/15589250221115722.
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This study presents an analysis of the possible use of a viscose rayon (CV) fiber from textile industry wastes to develop a reinforced cementitious composite as an alternative for textile discharge valorization. Several techniques were used to characterize precursor fibrous waste material such as SEM, FT-IR, DSC, and TGA. The experimental studies were conducted based on a conventional cementitious mortar (control) and four different fiber contents (0.5, 1, 2, and 4 wt%). For mechanical behavior analysis, uniaxial compressive strength tests were carried out at different ages (7, 14, and 28 days after production). The results showed favorable CV fiber addition as reinforcement up to a maximum limit. The optimum concentration of fiber was 0.5 wt% (FRC0.5), which provided 28 days of higher compression strength. The addition of CV waste as reinforcement in cementitious matrix resulted in an improved compressive strength above 20.6% compared to the conventional non-reinforced mortar. Furthermore, CV fiber addition improved the ductile behavior of the new composite allowing a controlled failure, even after maximum rupture loading.
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Murali, G., i Roman Fediuk. "A Taguchi approach for study on impact response of ultra-high-performance polypropylene fibrous cementitious composite". Journal of Building Engineering 30 (lipiec 2020): 101301. http://dx.doi.org/10.1016/j.jobe.2020.101301.
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Sharma, Natalia. "Study on Retrofitting and Strengthening of Reinforced Concrete Beams Using Fibrous Concrete". International Journal for Research in Applied Science and Engineering Technology 9, nr 8 (31.08.2021): 1676–84. http://dx.doi.org/10.22214/ijraset.2021.37637.
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Abstract: Reinforced concrete structures are frequently in need of repair and strengthening as a result of numerous environmental causes, ageing, or material damage under intense stress conditions, as well as mistakes made during the construction process. RC structures are repaired using a variety of approaches nowadays. The usage of FRC is one of the retrofitting strategies. Steel fiber reinforced concrete (SFRC) was used in this investigation because it contains randomly dispersed short discrete steel fibers that operate as internal reinforcement to improve the cementitious composite's characteristics (concrete). The main rationale for integrating small discrete fibers into a cement matrix is to reduce the amount of cement used. The principal reason for incorporating short discrete fibers into a cement matrix is to reduce cracking in the elastic range, increase the tensile strength and deformation capacity and increase the toughness of the resultant composite. These properties of SFRC primarily depend upon length and volume of Steel fibers used in the concrete mixture. In India, the steel fiber reinforced concrete (SFRC) has seen limited applications in several structures due to the lack of awareness, design guidelines and construction specifications. Therefore, there is a need to develop information on the role of steel fibers in the concrete mixture. The experimental work reported in this study includes the mechanical properties of concrete at different volume fractions of steel fibers. These mechanical properties include compressive strength, split tensile strength and flexural strength and to study the effect of volume fraction and aspect ratio of steel fibers on these mechanical properties. However, main aim of the study was significance of reinforced concrete beams strengthened with fiber reinforced concrete layer and to investigate how these beams deflect under strain. The objective of the investigation was finding that applying FRC to strengthen beams enhanced structural performance in terms of ultimate load carrying capacity, fracture pattern deflection, and mode of failure or not.
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Junger, Dominik, Johannes Storm, Steffen Müller, Michael Kaliske i Viktor Mechtcherine. "Increasing the Fatigue Resistance of Strain-Hardening Cement-Based Composites (SHCC) by Experimental-Virtual Multi-Scale Material Design". Materials 14, nr 19 (28.09.2021): 5634. http://dx.doi.org/10.3390/ma14195634.
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Strain-hardening cement-based composites are a promising class of materials for a wide variety of applications due to their considerable tensile strength and pronounced ductility caused by the development of multiple fine cracks. Nevertheless, the safe use of such composites requires sound knowledge of their mechanical behaviour under different types of loading, particularly under fatigue loading, while considering distinct influences like initial crack width and fibre orientation. To deepen this knowledge, single-fibre pull-out tests on PVA-fibres from a cementitious matrix were carried out to gain information about the micro-mechanical and degradation processes of the fibre. It could be shown that the fibres tend to rupture instead of being pulled out under quasi-static loading. When changing the loading regime to alternating loading, this failure mechanism shifts to pull-out. By varying the experimental parameters such as initial crack width, inclination angle or compressive-force level a clear influence on the fibre’s crack bridging capacity could be observed associated with effects on the degradation processes. Based on the data obtained, a micro-mechanical numerical model was developed to support the assumptions and observations from single-fibre pull-out tests and to enable predictions of the performance of the material on the microscale under cyclic loading.
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Jabir, Hussain A., Sallal R. Abid, Gunasekaran Murali, Sajjad H. Ali, Sergey Klyuev, Roman Fediuk, Nikolai Vatin, Vladimir Promakhov i Yuriy Vasilev. "Experimental Tests and Reliability Analysis of the Cracking Impact Resistance of UHPFRC". Fibers 8, nr 12 (4.12.2020): 74. http://dx.doi.org/10.3390/fib8120074.
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Ultra-high performance (UHP) concrete is a special type of fibrous cementitious composite that is characterized by high strength and superior ductility, toughness, and durability. This research aimed to investigate the resistance of ultra-high performance fiber-reinforced concrete (UHPFRC) against repeated impacts. An adjusted repeated drop mass impact test was adopted to evaluate the impact performance of 72 UHPFRC disc specimens. The specimens were divided into six mixtures each of 12 discs. The only difference between the mixtures was the types of fibers used, while all other mixture components were the same. Three types of fibers were used: 6 mm micro-steel, 15 mm micro-steel, and polypropylene. All mixtures included 2.5% volumetric content of fibers, however with different combinations of the three fiber types. The test results showed that the mixtures with the 15 mm micro-steel fiber absorbed a higher number of impact blows until cracking compared to other mixtures. The mixture with pure 2.5% of 15 mm micro-steel fiber exhibited the highest impact resistance, with percentage increases over the other mixtures ranging from 25 to 140%. In addition, the Weibull distribution was used to investigate the cracking impact resistance of UHP at different levels of reliability.
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Murali, G., Sallal R. Abid, Hakim S. Abdelgader, Y. H. Mugahed Amran, Mohammad Shekarchi i Krzysztof Wilde. "Repeated Projectile Impact Tests on Multi-Layered Fibrous Cementitious Composites". International Journal of Civil Engineering, 9.01.2021. http://dx.doi.org/10.1007/s40999-020-00595-4.
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Mermerdaş, Kasım, Süleyman İpek, Ahmed Motesem Anwer, Şevin Ekmen i Mustafa Özen. "Durability performance of fibrous high-performance cementitious composites under sulfuric acid attack". Archives of Civil and Mechanical Engineering 21, nr 4 (12.09.2021). http://dx.doi.org/10.1007/s43452-021-00298-0.
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Feldman, Dorel, i Zhihong Zheng. "Synthetic Fibres for Fibre Concrete Composites". MRS Proceedings 305 (1993). http://dx.doi.org/10.1557/proc-305-123.
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AbstractThe use of fibrous reinforcement to improve the strength and deformation properties of concrete is now well established. The concept of fibre reinforcement is to use the deformation of the matrix under stress to transfer load to the fibre. Substantial improvements in static and dynamic strength properties could then be achieved if the fibres are strong and stiff, and loaded to fracture, provided there is, of course, a minimum fibre-volume fraction.Besides fibres like asbestos, glass and steel, different kind of synthetic fibres such as polyethylene, polypropylene, polyamide and others are recently used for cementitious composites.Together with general aspects of synthetic fibre concrete composites, original results concerning the study done on a hybrid composite based on steel and polypropylene fibres will be presented and discussed.
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Samsudin 1*, Muhamad Fadli, Mahyuddin Ramli 1 i Cheah Chee Ban 1. "Mechanical properties and flexural behaviour of fibrous cementitious composites containing hybrid, kenaf and barchip fibres in cyclic exposure". Materials Science: Advanced Composite Materials 2, nr 4 (21.02.2019). http://dx.doi.org/10.18063/msacm.v0i0.812.
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In this study, the mechanical properties and flexural behaviour of the fibrous cementitious composites containing hybrid, kenaf and barchip fibres cured in cyclic exposure were investigated. Waste or by-product materials such as pulverized fuel ash (PFA) and ground granulated blast-furnace slag (GGBS) were used as a binder or supplementary cementitious to replace cement. Barchip and kenaf fibre were added to enhance the mechanical properties and flexural behaviour of the composites. A seven mix design of the composites containing hybrid, kenaf and barchip fibre mortar were fabricated with PFA-GGBS at 50% with hybridization of barchip and kenaf fibre between 0.5% and 2.0% by total volume weight. The composites were fabricated using 50 × 50 × 50 mm, 40 × 40 × 160 mm and 350 × 125 × 30 mm steel mould. The flexural behaviour and mechanical performance of the PFA-GGBS mortar specimens were assessed in terms of load-deflection response, load compressive response, and crack development, compressive and flexural strength after cyclic exposure for 28 days. The results showed that specimen HBK 1 (0.5% kenaf fibre and 2.0% barchip fibre) and HBK 2 (1.0% kenaf fibre and 1.5% barchip fibre) possessed good mechanical performance and flexural behaviour. As conclusion, the effect of fibres was proven to enhance the characteristics of concrete or mortar by reducing shrinkage, micro crack and additional C-S-H gel precipitated from the pozzolanic reaction acted to fill pores of the cement paste matrix and cement paste aggregate interface zone between mortar matrix and fibre bonding.
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Zhang, Juntao, i Tong Lv. "Hydration and durability of low-heat cementitious composites for dam concrete: Thermodynamic modeling and experiments". Frontiers in Materials 10 (17.01.2023). http://dx.doi.org/10.3389/fmats.2023.1120520.
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To demonstrate the superiority of dam concrete, a systematic study was conducted to examine the durability of low-heat cementitious composite (LHCC) that is composed of Portland cement (PC), fly ash (FA), and MgO expansive additive (MEA) with PC as the reference group. Through GEMS software, XRD, SEM, and EDS, the difference mechanism in durability between the two cementitious materials was revealed from the perspectives of phase evolution and microstructural characteristics. Water at 40 °C was adopted for curing in the study to match the long-term temperature field inside the concrete dam. According to the results of the RCM, accelerated carbonation, and rapid freeze–thaw cycle experiments, LHCC outperforms PC in durability. The hydration process of LHCC is simulated by inputting the reaction degree of each phase calculated using the MPK model into the GEMS software. The thermodynamic model output shows that portlandite first increases and then decreases as LHCC hydration proceeds, and C-S-H and stratlingite are supplemented in the later stage, which reflects the high performance of FA involved in hydration. In addition, hydrotalcite that is capable of chloride ion adsorption is increasingly generated with the consumption of brucite. As is clearly shown in the SEM images, there are denser space grids formed by overlapping C-S-H in LHCC with almost no capillary pores. Meanwhile, when combined with the results of EDS, it is strongly demonstrated that the FA in LHCC can be hydrated to produce dense fibrous C-S-H in large amounts, providing a basis for the positive development of durability.
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Zhu, Deqi, Aihua Wen i Aiping Tang. "Mechanical properties, durability and environmental assessment of low-carbon cementitious composite with natural fibrous wollastonite". Environmental Research, lipiec 2023, 116552. http://dx.doi.org/10.1016/j.envres.2023.116552.
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Vanorio, Tiziana, Jaehong Chung, Shalev Siman-Tov i Amos Nur. "Hydrothermal formation of fibrous mineral structures: The role on strength and mode of failure". Frontiers in Earth Science 10 (6.01.2023). http://dx.doi.org/10.3389/feart.2022.1052447.
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Studying the mechanisms that control the rheology of rocks and geomaterials is crucial as much for predicting geological processes as for functionalizing geomaterials. That requires the understanding of how structural arrangements at the micro and nano scale control the physical and mechanical properties at the macroscopic scale. This is an area of rock physics still in its infancy. In this paper, we focus the attention on the formation of cementitious phases made of micro- and nano-scale fibrous structures, and the controls of the arrangement of these phases on mechanical properties. We use hydrothermal synthesis, and the properties of hydrothermal water, to promote the growth of fibrous mineral phases having nano-size diameter and length of a few microns, creating disordered and entangled mats of fibrous bundles as those found in natural samples. We draw inferences from structural microscopy to inform a statistical model that establishes an interdependence between structural parameters of fibrous structures and bulk mechanical response. Structural parameters include number and length of fibers, spatial orientation, and fraction of fibrous threads bearing the load. Mechanical properties include strength and mode of failure. Results show that as the fibrous microstructure evolves from ordered and aligned to disordered and entangled, the mechanical response of the fibrous composite transitions from a brittle to ductile behavior. Furthermore, the disordered and entangled microstructure exhibits lower strength at failure though strength increases as the number of fibers within the microstructure increases. Finally, the longer the entangled fiber, the larger the strain that the matrix can accommodate. The value of this study lies in further understanding fault healing through hydrothermal fluids and how the physical properties of fibrous microstructures resulting from it control brittle-ductile transitions, and possibly, slow slip events along subduction zones.
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Tamilisetti Bhuvaneswara Reddy i Dr. B. Madhusudana Reddy. "Destructive and Non-Destructive Analysis of Polypropylene Fibre Reinforced Concrete". International Journal of Scientific Research in Science and Technology, 1.05.2023, 79–88. http://dx.doi.org/10.32628/ijsrst52310313.
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Plain Cement Concrete (PCC) is brittle and has low tensile strength. The brittleness can be avoided by adding fibre. Fibre-reinforced concrete (FRC) is concrete containing fibrous material spread across concrete, which increases its structural integrity. Addition of fibres to concrete makes it an isotropic material and converts its brittle behaviour to ductile behaviour. In the Fibre Reinforced Concrete, polypropylene fibres are rationally combined to produce a cementitious composite that derives benefits from each of the individual fibres and exhibits a synergistic response. Based on I.S. Code method of mix design, proportion of different ingredients was obtained to get M30 grade concrete. Samples were prepared with varying the volume fraction of fibres from 0.50% to 2.50%. The optimum dosage is determined from among the above mixes. The result shows that optimum dosage is obtained at 1.50% addition of fibre. The main aim of the present experimental investigation was to use different volume fractions of polypropylene fibres to produce FRC and thus to evaluate its performance by comparing Destructive tests such as compression, tension, flexure and Non-destructive tests such as Rebound Hammer, Ultrasonic Pulse Velocity and Durability Parameters such as Water Absorption, Sorpitivity etc., .From the results obtained fibre reinforced concrete shows higher values than normal concrete under Compression, Split Tensile and Flexural Strength. The water absorption is reduced for FRC compared to Normal Concrete.