Tensile Behaviour and Durability of Mortar-Based Strengthening Systems with Glass-Aramid Textiles

2014 ◽  
Vol 624 ◽  
pp. 346-353 ◽  
Author(s):  
Stefano de Santis ◽  
Gianmarco de Felice
Keyword(s):  
Mechanical Properties ◽  
Design Parameters ◽  
Tensile Behaviour ◽  
Masonry Structures ◽  
Hydraulic Lime ◽  
Experimental Campaign ◽  
Cement Mortars ◽  
Lime Mortars ◽  
The Matrix ◽  
Strength And Stiffness

Mortar-based composite materials are currently receiving great attention for strengthening masonry structures, especially when specific preservation criteria need to be fulfilled. Their mechanical properties and durability, however, still need to be fully investigated. An experimental campaign has been carried out to characterize the tensile behaviour of composite strengthening systems comprising glass-aramid textiles. First, textile specimens comprising either E-glass or AR-glass have been aged in alkaline environment, for different durations up to 1000 hours, and tested under tension to investigate their durability. Then, composite specimens have been manufactured with the AR-glass-aramid mesh and four different mortar matrices, ranging from strong mineral and cement mortars, to weak hydraulic lime mortars. Strength and stiffness, failure mode and response stages under tension have been identified and compared to those of the dry textiles to investigate the contribution provided by the matrix and derive design parameters for various field applications.

scholarly journals Properties of Latex Polymer Modified Mortars Reinforced with Waste Bamboo Fibers from Construction Waste

Buildings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 149 ◽  
Author(s):  
Banjo Akinyemi ◽  
Temidayo Omoniyi
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Latex Paint ◽  
Construction Waste ◽  
Calcium Silicate Hydrates ◽  
Cement Mortars ◽  
The Matrix ◽  
Bamboo Fibers ◽  
Pre Treatment ◽  
Scanning Electron

This study evaluated the properties of latex modified cement mortars from ordinary paints which were reinforced with treated bamboo fibers from construction waste. Fiber variations of 0, 0.5, 1 and 1.5% at 10% of the weight of cement were utilized. Mechanical properties were determined according to standards; similarly, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to analyze the microstructural and elemental properties of the samples. The experimental results revealed that the addition of 1.5% bamboo fibers and 10% latex solution produced excellent mechanical properties. This was as a result of improved fiber adhesion to the matrix through pre-treatment, coupled with the contributed high strength from the latex paint modified mortars. The micrograph showed that latex precipitated in the voids and on the surface of the bamboo fibers as well as gels of calcium silicate hydrates which contributed to the observed improvement in strength of the tested samples.

Mechanical Properties of Densified Untwisted Carbon Nanotube Yarn / Epoxy Composites

2015 ◽  
Author(s):  
Risa Yoshizaki ◽  
Kim Tae Sung ◽  
Atsushi Hosoi ◽  
Hiroyuki Kawada
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Polymer Matrix Composites ◽  
High Strength ◽  
Matrix Composites ◽  
Specific Strength ◽  
The Matrix ◽  
Cnt Arrays ◽  
Strength And Stiffness ◽  
Long Fibers

Carbon nanotubes (CNTs) have very high specific strength and stiffness. The excellent properties make it possible to enhance the mechanical properties of polymer matrix composites. However, it is difficult to use CNTs as the reinforcement of long fibers because of the limitation of CNT growth. In recent years, a method to spin yarns from CNT forests has developed. We have succeeded in manufacturing the unidirectional composites reinforced with the densified untwisted CNT yarns. The untwisted CNT yarns have been manufactured by drawing CNTs through a die from vertically aligned CNT arrays. In this study, the densified untwisted CNT yarns with a polymer treatment were fabricated. The tensile strength and the elastic modulus of the yarns were improved significantly by the treatment, and they were 1.9 GPa and 140 GPa, respectively. Moreover, the polymer treatment prevented the CNT yarns from swelling due to impregnation of the matrix resin. Finally, the high strength CNT yarn composites which have higher volume fraction than a conventional method were successfully fabricated.

scholarly journals Lime based Dry Mixes with Carbonate Aggregates

2019 ◽  
Vol 8 (11) ◽  
pp. 3289-3292 ◽  
Keyword(s):  
Mechanical Properties ◽  
Quartz Sand ◽  
Carbonate Rocks ◽  
Physical And Mechanical Properties ◽  
Lime Mortar ◽  
Fine Aggregates ◽  
Lime Mortars ◽  
The Matrix ◽  
Optimal Values ◽  
Quarry Dust

The use of carbonate rocks as aggregates for cement concretes and mortars is limited due to their insufficient strength and the threat of corrosion. The use of quarry dust from crushing carbonate rocks are technically and economically feasible in building compositions based on air-hardening lime. The results of the study of the effect of replacing a part of quartz sand in lime mortar by limestone and dolomite fine aggregates on the basic physical and mechanical properties of lime mortars for restoration are presented in the paper. The matrix of planning experiments, which allows increasing the informativity of the research results in order to reduce the number of experiments in the search for optimal values, is proposed. The efficiency of replacement of the quartz sand with quarry dust of carbonate rocks in the production of dry mixes for restoration is shown.

scholarly journals 3D printing of composites: design parameters and flexural performance

2020 ◽  
Vol 26 (4) ◽  
pp. 699-706
Author(s):  
Feras Korkees ◽  
James Allenby ◽  
Peter Dorrington
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Design Parameters ◽  
Content Type ◽  
Flexural Performance ◽  
3D Printed ◽  
Strength And Stiffness

Purpose 3D printing of composites has a high degree of design freedom, which allows for the manufacture of complex shapes that cannot be achieved with conventional manufacturing processes. This paper aims to assess the design variables that might affect the mechanical properties of 3D-printed fibre-reinforced composites. Design/methodology/approach Markforged Mark-Two printers were used to manufacture samples using nylon 6 and carbon fibres. The effect of fibre volume fraction, fibre layer location and fibre orientation has been studied using three-point flexural testing. Findings The flexural strength and stiffness of the 3D-printed composites increased with increasing the fibre volume fraction. The flexural properties were altered by the position of the fibre layers. The highest strength and stiffness were observed with the reinforcement evenly distributed about the neutral axis of the sample. Moreover, unidirectional fibres provided the best flexural performance compared to the other orientations. 3D printed composites also showed various failure modes under bending loads. Originality/value Despite multiple studies available on 3D-printed composites, there does not seem to be a clear understanding and consensus on how the location of the fibre layers can affect the mechanical properties and printing versatility. Therefore, this study covered this design parameter and evaluated different locations in terms of mechanical properties and printing characteristics. This is to draw final conclusions on how 3D printing may be used to manufacture cost-effective, high-quality parts with excellent mechanical performance.

scholarly journals Use of Bioceramics Enhanced with Effective Microorganisms as an Additive for Construction. Study of Physical and Mechanical Properties in Cement Mortars and Gypsum Plasters

2021 ◽  
Vol 11 (8) ◽  
pp. 3519
Author(s):  
Filomena Pérez-Gálvez ◽  
María Jesús Morales-Conde ◽  
Manuel Alejandro Pedreño-Rojas
Keyword(s):  
Mechanical Properties ◽  
Mercury Intrusion Porosimetry ◽  
Construction Materials ◽  
Physical And Mechanical Properties ◽  
Slight Improvement ◽  
Effective Microorganisms ◽  
Mercury Intrusion ◽  
Experimental Campaign ◽  
Cement Mortars ◽  
Scanning Electron

Biomaterials are materials that are used to manufacture devices that interact with biological systems. According to their chemical composition, they can be classified as biometals, biopolymers, bioceramics, biocomposites and semiconductors. Thus, in the present work, the application of bioceramics, enhanced with effective microorganisms, to construction materials (cement mortars and gypsum plasters) was studied in order to see the benefits that its incorporation contributes to construction materials. This first work constitutes the first phase of an experimental campaign in which the influence of bioceramics on the physical and mechanical properties (flexural and compressive strength) of the studied materials was analyzed. Furthermore, scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) techniques were used. According to the results, a slight improvement in the mechanical properties of the new composites was observed. Besides, a more compact matrix was observed when bioceramics were used as an aggregate to the mixtures.

Study of the pull-out test of multifilament yarns embedded in cementitious matrix

2020 ◽  
Vol 55 (2) ◽  
pp. 169-185
Author(s):  
Anne-Claire Slama ◽  
Jean-Louis Gallias ◽  
Bruno Fiorio
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cement Composite ◽  
Maximum Load ◽  
Variable Number ◽  
Tensile Behaviour ◽  
Cementitious Matrix ◽  
Pull Out ◽  
The Matrix ◽  
Multifilament Yarns

In order to understand the impregnation mechanism of a yarn by a cementitious matrix and its influence on the mechanical properties of a yarn/cement composite, pull-out tests have been performed on samples of yarn/cement. Two embedded lengths for the yarn and different rheological and mechanical properties for the matrix were tested. Two pull-out modes were distinguished according to the compressive strength of matrices. For matrices with a compressive strength between 60 and 70 MPa the pull-out mode is characterized by a behaviour close to the tensile behaviour of the yarn, with maximum load values reaching approximately 60% of the tensile maximum load because of filaments damages. For matrices with compressive strength inferior to 60 MPa, the pull-out mode exhibits a residual phase linked to a slippage and an extraction of a variable number of filaments, with lower maximum load values than the first pull-out mode. After pull-out test, for some samples with filaments extraction, an innovative method based on a double impregnation with resin enables to visualize the yarn/matrix interface and identify the level of impregnation of the filaments by using confocal microscopy. It is concluded that this level of impregnation has a direct influence on the mechanical behaviour of the embedded yarn, except for the slippage and extraction phase, but the rheological properties of the matrix has no significant influence on this impregnation.

Mechanical Properties of Csf/AZ91D Composites Fabricated by Extrusion Forming Process Directly Following the Vacuum Infiltration

2010 ◽  
Vol 89-91 ◽  
pp. 692-696 ◽  
Author(s):  
Ji Ming Zhou ◽  
Le Hua Qi ◽  
Hai Bo Ouyang ◽  
He Jun Li
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Short Fiber ◽  
Fiber Content ◽  
Vacuum Infiltration ◽  
Matrix Composites ◽  
Magnesium Matrix ◽  
Magnesium Matrix Composites ◽  
The Matrix ◽  
Strength And Stiffness

Magnesium matrix composites are attractive for weight critical application, such as automotive and aerospace components, because of its high specific strength and stiffness. Extrusion process directly following vacuum infiltration (EVI) can eliminate the porosity and obtain the well-aligned and uniform fiber distribution during the fabrication of Csf/AZ91D composite. This process combines the advantages of gas pressure infiltration, squeeze casting, and semi-solid extrusion. The mechanical properties of the magnesium are improved greatly by introducing the carbon fibers into the magnesium matrix through the EVI process. In the present study, the carbon short fiber reinforced magnesium matrix composites Csf/AZ91D were fabricated by EVI process. The microstructure and tensile property of Csf/AZ91D composites were investigated. The results showed that the microstructure of the composite presented a uniform distribution of carbon short fibers in the matrix and good interfacial integrity. The yield strength and stiffness of the composites increased with increasing carbon short fiber content, but at the cost of ductility. Nonetheless, Csf/AZ91D can keep relatively high ductility during the improvement of strength compared with reported composites in the literatures. Increasing carbon fiber content in the composite was not always beneficial to the ultimate tensile strength at the same magnitude. When the fiber content exceeds 10%, the matrix was not strengthened as greatly as under 10% fiber content. The yield strength improvement was attributed to (i) load-bearing effects due to the presence of carbon short fiber reinforcements; (ii) grain size refinement due to the large extrusion deformation; (iii) generation of dislocations to accommodate CTE mismatch between the matrix and the particles.

scholarly journals Nano-TiO2 in Hydraulic Lime–Metakaolin Mortars for Restoration Projects: Physicochemical and Mechanical Assessment

Buildings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 236
Author(s):  
Kali Kapetanaki ◽  
Chrysi Kapridaki ◽  
Pagona-Noni Maravelaki
Keyword(s):  
Mechanical Properties ◽  
Setting Time ◽  
Hydrated Lime ◽  
Pozzolanic Reaction ◽  
Plastic Behavior ◽  
Hydraulic Lime ◽  
Three Point Bending ◽  
Natural Pozzolans ◽  
Fine Aggregates ◽  
Lime Mortars

In recent years, lime mortars mixed with artificial or natural pozzolans are commonly used in restoration applications. The aim of this work is the assessment of carbonation, pozzolanic reaction, setting time, and mechanical properties of metakaolin–lime mortars mixed with crystalline nano-titania (nT) as additive. The studied mortars consist of hydrated lime and metakaolin in 60/40 ratio (wt%) and fine aggregates of either carbonate or silicate sand. The concentration of the nano-titania is equal to 6 (wt%) of the binder. For comparison purposes, three types of mortars and pastes are designed: Without the addition of nano-titania, with nT activated or not under UV irradiation. The evaluation of the carbonation and pozzolanic reaction over a 1.5-year curing period is carried out through thermal analysis (DTA/TG), infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). The uniaxial compression and the three-point bending tests at 28 days, 3 months, and 6 months were carried out to evaluate mechanical properties. The addition of activated nano-titania, due to an increased photocatalytic activity, accelerated the setting of the mortars, improving at the same time the mechanical properties. The plastic behavior of the lime–metakaolin mortars with activated nT was attributed to the evolution of carbonation and pozzolanic reaction.

scholarly journals THE INFLUENCE OF DOSAGE AND PRODUCTION PROCESS ON THE PHYSICAL AND MECHANICAL PROPERTIES OF AIR LIME MORTARS

2020 ◽  
Vol XLIV-M-1-2020 ◽  
pp. 351-356
Author(s):  
L. Garijo ◽  
X. X. Zhang ◽  
G. Ruiz ◽  
J. J. Ortega
Keyword(s):  
Mechanical Properties ◽  
Production Process ◽  
Free Water ◽  
Aggregate Size ◽  
Physical And Mechanical Properties ◽  
River Sand ◽  
Curing Conditions ◽  
Factors Affecting ◽  
Lime Mortars ◽  
The Matrix

Abstract. This paper studies the influence of five different factors affecting the dosage and production process of seven types of air lime mortars on their physical and mechanical properties. Such factors comprise the water/lime ratio, the aggregate type and size, the material of the mold and the curing conditions. Moreover, some physical and mechanical properties, not usually measured on air lime mortars, are obtained, such as open porosity, splitting tensile strength, fracture energy and elastic modulus measured through prisms. The results show that under the three different water/lime ratios tested, the material experiences a structural weakening. Ambient curing conditions were more favorable for air lime mortars than high humid ones. Moreover, it is observed that fabrication with wooden molds provided higher mechanical properties as they absorbed the free water, although this effect was probably local. Air lime mortar with an aggregate size of 2 mm had lower consistency in a fresh state as finer sands were more water demanding and the mechanical properties of this mortar were slightly lower than those of mortar with aggregate sizes of 0/4 mm. Furthermore, using limestone aggregates improved the continuity between the lime and the matrix. This fact resulted in higher mechanical properties of the mortars with limestone aggregates in comparison to those with river sand when maintaining the same water/lime ratios. This study can suppose a further step in the improvement of the dosage methodology of air lime mortars.

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