scholarly journals Incorporation of Natural Fibres in Rendering Mortars for the Durability of Walls

2021 ◽  
Vol 6 (6) ◽  
pp. 82
Author(s):  
Cinthia Maia Pederneiras ◽  
Rosário Veiga ◽  
Jorge de Brito
Keyword(s):  
Modulus Of Elasticity ◽  
Drying Shrinkage ◽  
High Water ◽  
Natural Fibre ◽  
Accelerated Ageing ◽  
Flax Fibres ◽  
Aesthetic Appearance ◽  
Cement Binder ◽  
Drying Rates ◽  
Adherence Strength

One of the main functions of renders, together with the overall aesthetic appearance of the building, is the protection of the walls against external aggressive actions, such as water, salts solutions, erosion, and mechanical impacts. However, some anomalies of renders may drastically hinder their protection ability. In fact, cracking, high water permeability, and loss of adherence to the substrate of renders limit their barrier effect and favour the exposure of the substrate to external actions. The incorporation of fibres in mortars is commonly pointed out to reduce their cracking susceptibility, due to the probable enhancement in tensile strength and ductility of the composite. The use of lime in substitution of the part of the cement binder is seen as a method to reduce the modulus of elasticity and therefore enhance the resistance to cracking due to drying shrinkage. Therefore, this study investigates the wall protection-related properties of natural fibre-reinforced renders with cement-lime as a binary binder at 1:1:6 volumetric ratio. With this purpose, wool, coir, and flax fibres are used at 20% by total mortar volume and the water behaviour, cracking susceptibility, and adherence to the substrate of the mortars are assessed. Specifically, the water absorption by capillarity, drying rates, permeability to water under pressure, adherence strength, and shrinkage are evaluated. In order to evaluate the renders’ durability and therefore the durability of the protection to the walls, an artificial accelerated ageing test is performed based on heating-freezing and humidification-freezing cycles. The results indicate that the fibres’ addition reduced the shrinkage and modulus of elasticity of the mortars, which suggests lower susceptibility to cracking. The addition of fibres in mortars seemed to slightly affect their water performance and only at early ages. From the results, it was concluded that the adherence strength is not affected by the fibres’ incorporation. The fibres seem also to reduce the impacts of the ageing cycles on the mortar and the improvements provided by the fibres’ addition to the mortars’ performance remained after ageing when compared to the mortars without fibres, thus being a potential alternative to increase their durability. These aspects are particularly important for buildings, since they can extend their service life and promote their sustainability.

scholarly journals Laccase-Enzyme Treated Flax Fibre for Use in Natural Fibre Epoxy Composites

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4529
Author(s):  
Hanna M. Brodowsky ◽  
Anne Hennig ◽  
Michael Thomas Müller ◽  
Anett Werner ◽  
Serge Zhandarov ◽  
...  
Keyword(s):  
Coupling Agent ◽  
Interfacial Strength ◽  
Fibre Surface ◽  
Tensile Tests ◽  
Single Fibre ◽  
Natural Fibre ◽  
Flax Fibre ◽  
Specific Strength ◽  
Flax Fibres ◽  
Afm Micrographs

Natural fibres have a high potential as reinforcement of polymer matrices, as they combine a high specific strength and modulus with sustainable production and reasonable prices. Modifying the fibre surface is a common method to increase the adhesion and thereby enhance the mechanical properties of composites. In this study, a novel sustainable surface treatment is presented: the fungal enzyme laccase was utilised with the aim of covalently binding the coupling agent dopamine to flax fibre surfaces. The goal is to improve the interfacial strength towards an epoxy matrix. SEM and AFM micrographs showed that the modification changes the surface morphology, indicating a deposition of dopamine on the surface. Fibre tensile tests, which were performed to check whether the fibre structure was damaged during the treatment, showed that no decrease in tensile strength or modulus occurred. Single fibre pullout tests showed a 30% increase in interfacial shear strength (IFSS) due to the laccase-mediated bonding of the coupling agent dopamine. These results demonstrate that a laccase + dopamine treatment modifies flax fibres sustainably and increases the interfacial strength towards epoxy.

Water Resistance and Tensile Strength of High Density Polyethylene (HDPE) Composites

2015 ◽  
Vol 1134 ◽  
pp. 34-38 ◽  
Author(s):  
Nurul Atiqah Mohd Ayob ◽  
Mansur Ahmad ◽  
Nurul Nadia Mohd Khairuddin
Keyword(s):  
Tensile Stress ◽  
Water Absorption ◽  
Modulus Of Elasticity ◽  
Tensile Modulus ◽  
Weight Fraction ◽  
Test Sample ◽  
Natural Fibre ◽  
Thickness Swelling ◽  
Fibre Composites ◽  
Coconut Coir

In this paper, three type of natural-fibre reinforced polyethylene were produced. They are the coconut coir reinforced polyethylene (RPCC), kenaf reinforced polyethylene (RPKC) and bamboo reinforced polyethylene (RPBC). Water absorption test, thickness swelling test and tensile test of the different natural fibre composites were carried-out. The mass of HDPE and natural fibre were based on percentage of filler loading. Each board types were produced with two fibre ratios which are at fourty percent and thirty percent. The preparation of the test sample is according to ASTM D1037 and ASTM D638. The tensile modulus of elasticity, tensile stress, water absorption and thickness swelling of kenaf and bamboo reinforced polyethylene composites were found to increase with increasing fibre weight fraction. Kenaf and bamboo composites showed compatible result for tensile stress and tensile modulus of elasticity while coconut coir appears to be otherwise. However, coconut coir fibre composites displayed comparable results to kenaf and bamboo for both water and thickness swelling. There were significant differences in both tensile properties and the percentage of the water absorption among composites.

scholarly journals Thermal Stability, Fire Performance, and Mechanical Properties of Natural Fibre Fabric-Reinforced Polymer Composites with Different Fire Retardants

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 699 ◽  
Author(s):  
Erik Valentine Bachtiar ◽  
Katarzyna Kurkowiak ◽  
Libo Yan ◽  
Bohumil Kasal ◽  
Torsten Kolb
Keyword(s):  
Mechanical Properties ◽  
Tensile Tests ◽  
Natural Fibre ◽  
Fire Retardants ◽  
Flax Fibres ◽  
Reinforced Polymer ◽  
Ul 94 ◽  
Mechanical Tensile ◽  
Vertical Test ◽  
Limited Oxygen

In this study, ammonium polyphosphate (APP) and aluminum hydroxide (ALH) with different mass contents were used as fire retardants (FRs) on plant-based natural flax fabric-reinforced polymer (FFRP) composites. Thermogravimetric analysis (TGA), limited oxygen index (LOI), and the Underwriters Laboratories (UL)-94 horizontal and vertical tests were carried out for evaluating the effectiveness of these FR treatments. Flat-coupon tensile test was performed to evaluate the effects of FR treatment on the mechanical properties of the FFRP composites. For both fire retardants, the results showed that the temperature of the thermal decomposition and the LOI values of the composites increased as the FR content increases. Under the UL-94 vertical test, the FFRP composites with 20% and 30% APP (i.e., by mass content of epoxy polymer matrix) were self-extinguished within 30 and 10 s following the removal of the flame without any burning drops, respectively. However, the mechanical tensile tests showed that the APP treated FFRP composites reduced their elastic modulus and strength up to 24% and 18%, respectively. Scanning electronic microscopic (SEM) for morphology examination showed an effective coating of the flax fibres with the FRs, which improved the flame retardancy of the treated composites.

scholarly journals Preliminary results of dry Deep Soil Mixing soil-cement composite testing

2018 ◽  
Vol 251 ◽  
pp. 01025 ◽  
Author(s):  
Klaudia Jendrysik ◽  
Monika Kiecana ◽  
Hubert Szabowicz
Keyword(s):  
Modulus Of Elasticity ◽  
Testing Machine ◽  
Cement Composite ◽  
Soil Condition ◽  
Strength Properties ◽  
Organic Content ◽  
Deep Soil ◽  
Soil Mixing ◽  
Soil Cement ◽  
Cement Binder

This paper provides results of testing made for soil-cement mixtures in dry mixing technology. This technology is greatly dependent on existing soil condition; hence the results are of highly random nature. Material used in testing was distinguished with high organic content and low humidity. Tests were carried out in laboratory of Wroclaw University of Technology on 145 samples as ordered by Menard Polska Ltd. Company. Samples were prepared and stored under laboratory conditions and then, after various maturation time, were destroyed in a testing machine. The purpose was to determine the stress-strain curves used to find strength properties, strain at failure, modulus of elasticity, secondary modulus of elasticity versus cement content. Test confirmed improvement of soil strength properties after addition of cement binder. The results may be used to determine the most economic binder-to-soil ratio.

scholarly journals Water Absorption Behaviour and Its Effect on the Mechanical Properties of Flax Fibre Reinforced Bioepoxy Composites

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
E. Muñoz ◽  
J. A. García-Manrique
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Natural Fibre ◽  
Flax Fibre ◽  
Fickian Diffusion ◽  
Time Duration ◽  
Flax Fibres ◽  
Positive Effects ◽  
Rtm Process ◽  
Potential Applications

In the context of sustainable development, considerable interest is being shown in the use of natural fibres like as reinforcement in polymer composites and in the development of resins from renewable resources. This paper focuses on eco-friendly and sustainable green composites manufacturing using resin transfer moulding (RTM) process. Flax fibre reinforced bioepoxy composites at different weight fractions (40 and 55 wt%) were prepared in order to study the effect of water absorption on their mechanical properties. Water absorption test was carried out by immersion specimens in water bath at room temperature for a time duration. The process of water absorption of these composites was found to approach Fickian diffusion behavior. Diffusion coefficients and maximum water uptake values were evaluated; the results showed that both increased with an increase in fibre content. Tensile and flexural properties of water immersed specimens were evaluated and compared to dry composite specimens. The results suggest that swelling of flax fibres due to water absorption can have positive effects on mechanical properties of the composite material. The results of this study showed that RTM process could be used to manufacture natural fibre reinforced composites with good mechanical properties even for potential applications in a humid environment.

Natural Fibre/Polypropylene Wrap Spun Yarns and Preforms for Structured Thermoplastic Composites

2011 ◽  
Vol 675-677 ◽  
pp. 427-430 ◽  
Author(s):  
Jin Hua Jiang ◽  
Ze Xing Wang ◽  
Nan Liang Chen
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Hot Pressing ◽  
Mechanical Performance ◽  
Great Influence ◽  
Natural Fibre ◽  
Thermoplastic Composites ◽  
Flax Fibres ◽  
Fibre Composites ◽  
Spun Yarns

In the past decade, natural fibre composites with thermoplastic matrices had attracted many composites manufactures for the superiority of lightweight and low-cost. A major challenge for natural fibre composites was to achieve high mechanical performance at a competitive price. Composites constructed from yarn and fabric structure preforms were better than composites made from random nonwoven mats. However, the twist structure of conventional ring spun yarns prevented the full utilization of fibre mechanical properties in the final composites. In this paper, the wrapped yarns were produced by wrap spun method with flax and polypropylene (PP), in which all flax fibres were twistless, then woven to be fabric preforms. The PP fibres served as a carrier for flax fibres during processing and became the polymer matrix in the final composites. The homogenous distribution of fibre and thermoplastic matrix in preforms could be achieved before hot pressing, so that not lead to impregnate difficultly, and prevented damage to the reinforced nature fibres during processing. Composites made from the wrapped yarn demonstrated significant tensile and peeling properties. The fabric structures (include plain, twill, and basket weave) and yarn tensile orientation (in 0°, 90°, 45°), had great influence on tensile strength and elongation of preforms. The cavity thickness of hot pressing mould had different influence on the tensile strength and peeling strength of thermoplastic composites, and the mechanical properties were superior when the thickness was 0.8-1.2 mm. The microstructure of thermoplastic composites showed uniform infiltration between layers, and had good bonding interface between flax fibre and PP matrix in composites.

Mechanical Properties of Kenaf - Unsaturated Polyester Composites: Effect of Fiber Treatment and Fiber Length

2011 ◽  
Vol 311-313 ◽  
pp. 260-271 ◽  
Author(s):  
E. Osman ◽  
A. Vakhguelt ◽  
I. Sbarski ◽  
S. Mutasher
Keyword(s):  
Modulus Of Elasticity ◽  
Natural Fiber ◽  
Unsaturated Polyester ◽  
Weight Fraction ◽  
Weight Percent ◽  
Natural Fibre ◽  
Kenaf Fiber ◽  
Regular Trend ◽  
Theoretical Predictions ◽  
Naoh Solution

Kenaf fibre is a natural fibre which is growing in popularity due environmental issues and its properties as filler. Unsaturated polyester was used in this investigation via add 1% MEKP concentration ratio as the catalyst. This matrix was combined with untreated kenaf fiber with various fiber sizes (1-6) mm and (10-30) mm, alkalized with 6% NaOH solution for treated kenaf fiber to form natural fiber for two different fiber lengths composites. Composites were prepared by adding various percentages of kenaf fiber in unsaturated polyester resin. A general trend was observed whereby alkalized fiber composites possessed superior flexural strength and modulus and the maximum strength and modulus was at the 20wt% weight fraction. The length of (10-30) mm gave higher tensile and flexural properties compared to (1-6) mm. The modulus of elasticity showed a regular trend of an increase with fiber weight percent until 30% for both fiber lengths and afterwards a decrease in modulus of elasticity for composites with greater fiber weight fraction. The experimental modulus of elasticity was compared with the theoretical predictions and was found to be in good agreement with Hirsch’s model while the results obtained from Cox – Krenchel underestimating the experimental data.

scholarly journals Experimental Study on the Shrinkage Behavior and Mechanical Properties of AAM Mortar Mixed with CSA Expansive Additive

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3312 ◽  
Author(s):  
Sung Choi ◽  
Gum-Sung Ryu ◽  
Kyeong-Taek Koh ◽  
Gi-Hong An ◽  
Hyeong-Yeol Kim
Keyword(s):  
Modulus Of Elasticity ◽  
Compensation Effect ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Shrinkage Stress ◽  
Calcium Sulfoaluminate ◽  
Total Shrinkage ◽  
Expansive Additive ◽  
Shrinkage Compensation

In this study, a calcium sulfoaluminate-based expansive additive (0%, 2.5%, 5.0%, and 7.5% by the mass of the binder) was added to compensate for the shrinkage of alkali-activated material (AAM) mortar. Modulus of elasticity curves based on the ACI 209 model were derived for the AAM mortar mixed with the additive by measuring the compressive strength and modulus of elasticity. Moreover, autogenous shrinkage and total shrinkage were measured for 150 days, and drying shrinkage was calculated by excluding autogenous shrinkage from total shrinkage. For the autogenous and drying shrinkage of AAM mortar, shrinkage curves by age were obtained by deriving material constants using the exponential function model. Finally, shrinkage stress was calculated using the modulus of elasticity of the AAM mortar and the curves obtained using the shrinkage model. The results showed that the calcium sulfoaluminate-based expansive additive had an excellent compensation effect on the drying shrinkage of AAM mortar, but the effect was observed only at early ages when the modulus of elasticity was low. From a long-term perspective, the shrinkage compensation effect was low when the modulus of elasticity was high, and thus, shrinkage stress could not be reduced.

Copolymer of natural fibre reinforced polyester urethane: effect on physico-chemical properties through modification to interfacial adhesion

2016 ◽  
Vol 36 (2) ◽  
pp. 189-197
Author(s):  
Gabriela Jandikova ◽  
Pavel Kucharczyk ◽  
Norbert Miskolczi ◽  
Alena Pavelkova ◽  
Adriana Kovalcik ◽  
...  
Keyword(s):  
Interfacial Adhesion ◽  
Alkali Treatment ◽  
Chemical Properties ◽  
Gel Permeation Chromatography ◽  
Natural Fibre ◽  
Special Focus ◽  
Scanning Calorimetry ◽  
Polyester Urethane ◽  
Flax Fibres ◽  
Physico Chemical

Abstract This work is dedicated to polyester urethane (PEU)-based biocomposites, with special focus placed on techniques for compatibilisation to heighten interfacial adhesion between the PEU matrix and flax fibres. Tests were conducted on the effects of modification so as to increase interfacial adhesion between the flax fibres and the polyester matrix. These tests involved a commercial silane-based compatibilising additive, two experimentally synthesised agents, oleic acid (OA) and di-tert-butyl peroxide (DTBP). Furthermore, the flax fibres underwent acid or alkali treatment. The biocomposites were characterised by gel permeation chromatography, infrared spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Mechanical properties were investigated through tensile testing. Biocomposites with a commercial silane-based additive and synthesised agent, based on maleic-anhydride, were assessed as the best solution. Nevertheless, all modifications, excluding alkali treatment of fibres, significantly increased the performance of the material.

Life Cycle Assessment of Natural Fibre Reinforced Cementitious Composites

2018 ◽  
Vol 761 ◽  
pp. 204-209 ◽  
Author(s):  
Ildiko Merta ◽  
Ana Mladenovič ◽  
Janez Turk ◽  
Aljoša Šajna ◽  
Alenka Mauko Pranjić
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Natural Fibre ◽  
Natural Fibres ◽  
Cementitious Composites ◽  
Aquatic Ecotoxicity ◽  
Flax Fibres ◽  
Sea Grass ◽  
The Matrix ◽  
Composite Mixture

Three cementitious composites containing different natural fibres (flax, hemp and sea-grass) were evaluated from an environmental perspective by means of Life Cycle Assessment (LCA) method applying the cradle-to-gate approach. The environmental impact of these composites was compared to that of cementitious composites reinforced with conventional synthetic polyacrilonitrile (PAN) fibres. The functional unit was the production of one cubic meter of cementitious composites ready-for-use. The results show that generally the environmental footprint of composite with synthetic fibres is bigger than the footprint of the composites with added natural fibres. Exceptions may only be the impacts on eutrophication and freshwater aquatic ecotoxicity, which are significantly affected by cultivation of crops. Flax and hemp cultivation is associated with emissions to soil and water. For this reason, the composite mixture with flax fibres has a significantly greater impact on eutrophication and freshwater aquatic ecotoxicity than the composite mixture with synthetic fibres. A cementitious composite mixture with sea-grass shows the lowest impacts in all impact categories. The entire life cycle of the studied composites was not included in this research since the life cycle of natural fibre composites is not straightforward and is highly dependent on the durability of the fibres within the matrix.

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