Number Of Mesh Layers Research Articles

In and out of plane behaviour of TRM strengthened heritage masonry elements

This paper presents detailed experimental and analytical investigations into the influence of textile-reinforced mortar (TRM) strengthening on the in-plane and out-of-plane response of unreinforced heritage masonry (URM) elements. The URM wall elements consist of hydraulic lime mortar and fired-clay bricks, and the TRM reinforcement employs mortar-embedded layers of alkali age-resistant glass meshes. Apart from the material characterisation tests on mortars, bricks, and TRM coupons, the experimental programme includes axial compression tests on wallettes, diagonal compression tests on square panels, as well as four-point bending tests on rectangular panels. In the latter, the bending loads are applied either parallel or perpendicular to the bed joints in order to assess the joint layout effect on the behaviour. With the aid of digital image correlation, the in-plane and out-of-plane enhancement in stiffness, strength, and ductility of the masonry elements due to the TRM strengthening is quantified, while the TRM influence on the crack patterns and failure modes is also examined. The results show that the number of mesh layers has a significant influence on the behaviour for the out-of-plane bending tests but plays a less pronounced role in the in-plane shear cases. Modified analytical models for the in-plane shear and out-of-plane bending capacities of reinforced masonry elements, of the type examined in this study, are also proposed and assessed alongside existing codified procedures. The application of current code provisions results in overly conservative estimates. In contrast, the proposed analytical approaches for determining the in-plane and out-of-plane strength provide close prediction of the experimental capacities from this study as well as those from a wider collated database of previous tests, and are therefore suitable for implementation in practical assessment and rehabilitation guidelines.

Durability performance of geopolymer ferrocement panels prepared by different alkaline activators

Ferrocement is a composite material consisting of a steel mesh bonded mortar used to form thin sections in numerous applications. Corrosion of ferrocement is more critical than the conventional reinforced concrete because of the small diameter of wire mesh and small concrete cover. This study aims to investigate the durability of fly ash-based geopolymer ferrocement composites. The accelerated corrosion test was conducted on ferrocement panel specimens with various affecting parameters. Series of ferrocement panel specimens were cast. The studied parameters included; type of steel wire mesh (welded, woven and expanded), thickness of panel specimens (20, 25 and 30 mm), number of mesh layers (1, 2 and 3 layers) and type of mortar mixtures. Four geopolymer (GP) mortar mixes were prepared with four different alkaline solutions. The alkaline solutions were a mixture of sodium silicate (NS), sodium hydroxide (NH), potassium silicate (KS) and potassium hydroxide (KH) as NS + NH, NS + KH, KS + NH and KS + KH. Parallel with the investigated GP mixture, a Portland cement mix was prepared. All mortar mixes were exposed to different aggressive environments including 5% sulphuric acid (H2SO4) and sodium sulphate for 24 weeks as well as water absorption test was conducted. Test results indicated that using a thicker steel mesh such as woven mesh, a thicker mortar cover and more than one layer in ferrocement panel specimens provides more resistance against reinforcement corrosion. The investigated GP mortar mixes provide a good passivation protection than cement mortar. Moreover, the fly ash-based GP mortar activated by NS showed passivation protection of steel wire mesh greater than the fly ash-based GP mortar activated by KS and showed a higher resistance to sodium sulphate and sulphuric acid exposure.

Local refinement with arbitrary irregular meshes and implementation in numerical manifold method

The solution accuracy based on finite element interpolation strongly depends on mesh quality. Thus, the numerical manifold method advocates that if a finite element mesh is selected as the mathematical cover, the mesh should be uniform, where all elements are congruent squares or isosceles right triangles for two-dimensional problems. However, the elements close to the points of stress concentrations or singularities must be smaller than those further away from these points. This leads to an irregular mesh in which a few nodes of certain small elements are hung on the edges of adjacent larger elements. This study implements local refinement with arbitrary k-irregular meshes by selecting piecewise polynomials as the local approximations over physical patches and enforcing appropriate constraints on the piecewise polynomials. All the elements are ordinary isoparametric elements, and elements with variable numbers of nodes on edges are not required. No linear dependency issue exists. Furthermore, refinement with any number of mesh layers is developed so that solution error can be distributed as uniformly as possible. Typical examples with different singularities are designed to illustrate the effectiveness of the proposed procedure.

Structural behavior of concrete walls reinforced with ferrocement laminates

The present work focuses on experimental and numerical performance of the ferrocement RC walls reinforced with welded steel mesh, expanded steel mesh, fiber glass mesh and tensar mesh individually. The experimental program comprised twelve RC walls having the dimensions of 450 mmx100 mmx1000 mm under concentric compression loadings. The studied variables are the type of reinforcing materials, the number of mesh layers and volume fraction of reinforcement. The main aim is to assess the influence of engaging the new inventive materials in reinforcing the composite RC walls. Non-linear finite element analysis; (NLFEA) was carried out to simulate the behavior of the composite walls employing ANSYS-10.0 Software. Parametric study is also demonstrated to check out the variables that can mainly influence the mechanical behavior of the model such as the change of wall dimensions. The obtained numerical results indicated the acceptable accuracy of FE simulations in the estimation of experimental values. In addition, the strength gained of specimens reinforced with welded steel mesh was higher by amount 40% compared with those reinforced with expanded steel mesh. Ferrocement specimens tested under axial compression loadings exhibit superior ultimate loads and energy absorbing capacity compared to the conventional reinforced concrete one.

Flexural behavior of one-way ferrocement slabs with fibrous cementitious matrices

Concrete compressive strength enhancement is considered as one of the popular topics in the field of civil engineering. It has received a massive attention by material and structural engineers over the past decades. The aim of this study is to investigate thin mortar matrix for the impacts of the combination of reinforcing steel meshes with discontinuous fibers, and to do this, one-way Ferrocement slabs were tested under bending with steel fibers and meshes, focusing more on the number of mesh layers (1, 2, & 3) as the studied parameter. The percentages of fiber content as volumetric ratio 0.25, 0.5 and 0.75 and type of fibers golden steel fibers and waste aluminum fibers from waste metallic cans. Results showed that at general the adding of fibers regardless of its type increased the ductility of tested slabs. In addition, results showed that steel fibers are more effective than aluminum fibers.

Axial compressive behaviour of concrete strengthened with steel rings, wire mesh and modified high strength mortar (MHSM)

This paper presents an investigation on the axial compression behaviour of concrete strengthened with an innovative composite, which comprises relatively high strength steel rings, wire mesh and modified high strength mortar (MHSM). In total, 38 cylindrical specimens divided into three groups were tested. The parameters studied are the ring spacing and the number of mesh layers. The results show that this composite can effectively improve the load carrying capacity, deformation capacity, ductility and energy absorption of the strengthened concrete specimens. The axial compression behaviour is predominantly governed by steel rings. As a secondary confinement, wire mesh markedly enhances ductility. The results indicate that MHSM has significant influence on the ultimate load and concrete strengthened with sufficient amount of wire mesh is potentially comparable to that with a low steel volumetric ratio. It was observed that steel rings did not reach the yield stress at the second peak load. Different models for predicting the ultimate load are discussed. The proposed empirical models provide prediction with reasonable accuracy.

Formulized average surface binding energy elevation and lithium vaporization and redeposition investigations in capillary pore systems

An investigation into lithium evaporation and redeposition with multi-mesh capillary pore systems (CPS) has been performed on a one-cathode linear plasma device. A diagnostic system has been used to monitor the lithium evaporation process in the vicinity of the specimen surface, with the adjustable plasma parameters of electron temperature ranging from 0.4–0.9 eV and electron density from 0.8–3.2 × 1019 m−3. The experimental results show that the lithium evaporation rate follows the reduction scaling ratio of 1.94:1.69:1.00 as the number of mesh layers is increased from two to four, which is closely related to the time-dependent fraction weighted average surface binding energy (i.e. evaporation heat) elevation because a fraction of lithium atoms is adhered to the mesh surface. From the viewpoint of nanoscale physics, a new formula is derived for the first time to qualitatively explain the physical mechanism of evaporation heat, or of time-dependent fraction weighted dual average surface binding energy with minor elevation in this special concomitant configuration CPS, which consists of liquid lithium and multi-meshes. The reason for this phenomenon is that the mesh surface binding force acts on a fraction of the adhered lithium atoms, leading to a minor elevation in the evaporation heat. The lithium vapor plays a modest shielding role from the incident heat flux dumping by stopping power plus lithium impurity radiation enhancement, as in the impurity radiation divertor, otherwise the thermal equilibrium of the system could not be attained. In addition, an experimental comparison with a nonactive target and a semi-empirical temperature-dependent model calculation have been applied to further verify the shielding effect. It has been observed that the redeposition rate increases with the applied discharge current.

Comparative study of ferrocement panels reinforced with galvanized iron and polypropylene meshes

Abstract Ferrocement panels reinforced with galvanized iron (GI) mesh have been in use historically, however in the regions where humidity levels are high the GI mesh tends to corrode, leading to reduced service life. Polypropylene (PP) mesh, having rust free character, may serve as an alternative to GI mesh. This paper presents an experimental study intended to compare the flexural and compressive strength behavior of ferrocement panels reinforced with GI and PP meshes. A total of 32 rectangular ferrocement panels were tested: 16 in flexure and 16 in compression. Out of 16 panels tested in flexure, 8 were reinforced with GI mesh and 8 with PP mesh. Similarly, 8 GI and PP mesh panels each were test in compression. The specimens tested in flexure were simply supported on two short edges and were tested under four point bending. The specimens tested in compression were hinged at both ends. The parameters investigated include thickness of panels, volume fraction and the material of the mesh. All the GI mesh panels outclassed the PP mesh panels both in flexure and compression strength. However, PP mesh panels exhibited better ductility properties as compared to GI mesh panels. The load carrying capacity of both GI and PP mesh panels increased with the increase in panel thickness and number of mesh layers.

Magnetic activated cell sorting (MACS) pipette tip for immunomagnetic bacteria separation

Magnetic activated cell sorting is a well-established technology to sort target cells from heterogeneous cell populations based on their specific surface receptors. However, conventional bulk separators rely on irregular and dense ferromagnetic matrices that can cause variances in separation purity and recovery. Recent microfluidic separators typically use narrow and two-dimensional laminar flows that can lead to low separation throughput. Here, we present a magnetizable micropipette tip incorporating a ferromagnetic matrix of nickel meshes that have regular and rectangular micropores. The functional pipette tip can be transiently magnetized by permanent magnets, thereby enabling the efficient capture and release of target cells by simple pipetting. We performed parametric studies to investigate optimal separation protocols such as the number of mesh layers and pipetting repetitions. We then applied the functional pipette tip for separation of bacterial cells from whole blood, confirming that the separation quality is sufficient for downstream cell culture and analysis. The magnetizable pipette tip provides high-throughput separation, processing 1 mL of blood within 7 min, and high-recovery separation, recovering ≈90.5% of the bacterial cells spiked into blood.

Torsional behaviour of normal strength RCC beams with ferrocement “U” wraps

Wrapping technology is one of the effective ways of strengthening concrete elements. Several researchers reported the effectiveness of Glass fiber reinforced polymers and carbon fiber reinforced polymers for improving the strength of the concrete elements. Wrapping on three sides is one of the effective methods for strengthening the beams supporting slabs. Scant literature is available on the strength enhancement of ?U? wrapped concrete elements subjected to torsional loads. In this investigation an attempt is made to quantify the improvement in the behaviour of ?U? wrapped rectangular concrete members subjected to torsional loads ?U? wraps. Ferrocement is taken here as wrapping material. Beams were cast with different number of mesh layers with different torsional reinforcement. The beams were analyzed with MARS. The predictions are in good agreement with experimental test results.

Улавливание аэрозольных частиц фильтрами из пористых сетчатых металлов

Results of experimental investigations related to filtration efficiency of aerosol particles from a dusty air flow by filtering
 baffles made of porous mesh materials by multiply packages of wire meshes hot rolling in vacuum have been represented. It
 has been found that capture of aerosol particles in these materials is mainly carried out by mechanisms of inertial capture
 and contact. The functional connection for particles’ fractional breakthrough coefficient from number of mesh layers in the
 package and its material porosity has been obtained. The analytical relation between fractional breakthrough coefficient
 and material porosity and Stokes number has been obtained based on experimental data processing. These studies results
 allow by appropriate selection of mesh number, quantity of meshes layers in the package and the package compression
 degree during rolling obtain a filter material with desired performance characteristics.

Torsional behaviour of reinforced concrete beams with ferrocement U-jacketing—Experimental study

Wrapping technology is one of the effective ways of strengthening concrete elements. Several researchers reported the effectiveness of Glass fiber reinforced polymers and carbon fiber reinforced polymers for improving the strength of the concrete elements. Wrapping on three sides is one of the effective methods for strengthening the beams supporting slabs. Available literatures on the strength enhancement of “U” wrapped concrete elements subjected to torsional loads do not give a detailed insight, whereas this investigation is an attempt to address the issues with ferrocement “U” wrap. Ferrocement “U” wraps are preferred over FRPs because of its cost factor. The “U” wraps are found to provide better torque carrying capacity under all states of torsion while under reinforced members provide better toughness over other states of torsion. Similarly completely over reinforced beams provide more torque resisting capacity than the others. Increase of torsional capacity is more prominent in states of torsion while improvement in torsional strength with number of mesh layers in ferrocement “U” wrap is minimal.

Flexural Behavior of Ferrocement Plates Incorporating Steel and PET Fibers

Ferrocement plate with steel meshes incorporating fibers in an identical matrix were tested under bending. The main objective of the study was to investigate the effects of combining reinforcing steel meshes with discontinuous fibers as reinforcement in thin mortar matrix. The variable parameters were chosen as (a) number of mesh layers, single and double (b) the types of fiber i.e steel and polyethylene terephthalate (PET). Everything else being equal, the test results shows that addition of steel fibers to the matrix of ferrocement can effectively increase its flexural strength and energy absorption to failure. Cracking and spalling of mortar cover also significantly reduced. On the other hand, the contributions of same volume fraction of PET fibers are not significant compared to steel. However, addition of PET fibers control the early cracking of thin mortar and showed slight improvement in flexural strength and energy absorption to failure compared to control specimens. Reinforcing ferrocement plates incorporating steel or PET fibers is recommended for providing technical and economical advantages as no negative effect was observed.

Analytical Model for Torsional Response of RC Beams Strengthened With Ferrocement U-Wraps

Wrapping technology is one of the most effective ways of strengthening concrete elements. Several research articles have confirmed the effectiveness of fibre-reinforced polymers (FRP) as wrapping material for enhancing the strength of reinforced concrete (RC) elements. Wrapping three sides of RC members is a convenient method of strengthening the beams that support the slabs. Its cost effectiveness over FRP makes ferrocement a good substitute as a wrapping material for strengthening RC beams. Limited research is reported regarding the torsional strength of ferrocement U-wrapped RC beams subjected to pure torsional loads. In this paper, an analytical model to predict the torsional response of RC beams with ferrocement U-wraps is presented. This analytical model is based on Hsu’s softened membrane model. The analytical model is validated by conducting experimental tests. In this investigation, 12 RC beams wrapped with ferrocement on three sides are tested under pure torsional loading. The different categories of beams tested in this investigation are under-reinforced beams, partially over-reinforced beams (longitudinal and transverse) and completely over-reinforced beams. The variations of U wraps considered in this investigation are three, four and five layers of mesh reinforcement in the ferrocement. The test results indicate that the cracking torque does not depend on the number of mesh layers present in the ferrocement wrapping. Ferrocement wrapping is more effective in the post-cracking stage than in the pre-cracking stage. The increase in the number of mesh layers in the ferrocement increases the ultimate torsional strength of the wrapped beam irrespective of the categories mentioned. The proposed analytical model is capable of predicting the torsional response with reasonable accuracy.

Characteristics of ferrocement thin composite elements using various reinforcement meshes in flexure

This article focuses on the experimental investigation carried out on the characteristics of ferrocement thin composite elements using various reinforcement meshes in flexure. The parameters of this study include: the effect of the various kinds of reinforcement meshes (stainless steel meshes and E-fiberglass meshes); number of mesh layers and various mesh diameters with opening size as well as various kinds of mortar materials as matrix (cement grout mortar and polymer— cement grout mortar) on the first crack load; bending stiffness; ultimate flexural load; load—deflection behavior; crack characteristics; energy absorption capacity; and ductility index. The results clarify that the use of stainless steel meshes as reinforcement system in the ferrocement thin composite elements contributes significantly to the improvement of bending characteristics in terms of first crack load, bending stiffness, ultimate flexural load, energy absorption to failure, and numerous fine and well-distributed cracks with a smaller width than while using fiberglass meshes. The method outlined by ACI Building Code is used to compute ultimate moment capacities. The results obtained using this method are compared with the experimental results.

Cement Composites Reinforced with Surface Modified Coir Fibers

An experimental investigation of coir mesh reinforced mortar (CMRM) is conducted using nonwoven coir mesh matting. The main parameters in this study are the fiber volume fraction (number of mesh layers) and fiber surface treatment with a wetting agent. The composites are subjected to the four-point bending test. The short-term mechanical properties of CMRM are discussed. Scanning electron micrograph analysis is used to observe the fiber—matrix interfacial characteristics. The results indicate that the addition of coir mesh to mortar significantly improves the composite post-cracking flexural stress, toughness, ductility, and toughness index, compared to plain mortar materials. The Albatex © FFC wetting agent (2-ethylhexanol) can effectively improve water absorption of coir fiber and enhance the fiber—matrix bonding strength. These coir mesh reinforced composites may be useful in civil engineering applications.

Flexural response of ferrocement with fibrous cementitious matrices

Bending tests were conducted on ferrocement specimens with steel meshes and fibers. The main objective of the study was to investigate the effects of combining reinforcing steel meshes with discontinuous fibers as reinforcement in thin mortar specimens. The following variables were investigated (a) number of mesh layers, 2 and 4 (b) transverse wire spacing, small, medium and large (c) the type of fiber, steel and glass. Everything else being equal, the addition of brass coated steel fibers to the matrix of ferrocement can effectively increase its flexural strength, energy absorption to failure, and significantly reduce the average crack spacing and width, and prevent spalling of the mortar cover at ultimate load. On the other hand, the addition of glass fibers to smaller spacing meshes provided a marginal improvement in flexural strength and considerable energy absorption to failure compared to control specimens. Reinforcing ferrocement matrices with brass coated steel fibers is strongly recommended for providing technical and economical advantages.

Characterization of Saturated Flow within Mesh-Type Wicks Based on the Capillary Suction Potential Corrected Using the Tortuosity

A relation of the friction factor cf to the Reynolds number Re, cfRe = 24, in mesh-type wicks has been deduced on the basis of a capillary bundle model, using the modified j-function of single-layer polyethylene mesh wicks measured by an electric resistance method. Correlation of the capillary drain height and the capillary drain number has yielded the tortuosity as a function only of the porosity. The cf and Re values calculated using the estimated tortuosity have proved the relation cfRe = 24 to be applicable to plain-woven stainless meshes as well as plain-woven and knitted-type polyethylene meshes, irrespective of the mesh number and the number of mesh layers constituting the wick.The results for the multi-layer mesh wicks have also reasonably supported that the modified j-function would be available even for the mesh wicks where the porosity increases by 12% or decreases by 14% compared to those of the single-layer mesh wicks.

Ferrocement bolted shear joints: Failure modes and strength prediction

An experimental investigation was carried out to study the behavior of ferrocement bolted shear joints. Twenty-eight different pin-loaded ferrocement plate configurations and eight control specimens were tested. The test variables were the type of mesh (square, hexagonal, mixed), mesh orientation ( 0 90 ° or ±45 °), number of mesh layers (2 to 8 corresponding to a volume fraction from 1.68% to 6.72%), and ratio between end distance and hole diameter ( e d = 4 or 6 ). Three failure modes were observed, net tensile section failure, cleavage failure, and crushing compression failure at the bolt. Cleavage failure was predominant for e d = 4 , and net-section tension failure or compression crushing for e d = 6 . The strength of the mesh reinforcement was closely related to the strength of the specimens that failed in the cleavage and net-section modes. Prediction equations are developed based on the Limit analysis Lower Bound Theorem to predict the net tension or cleavage failure loads, and a conservative equation is proposed to predict compression crushing failure. A comparison was made with other prediction equations available in the literature.

Implement Technique of Absorption Boundary Condition in Thompson-Fdtd Method

Thompson-FDTD (T-FDTD) method has been recently introduced to solving electromagnetic scatterings of irregular objects [1]. In this paper, we describe how to apply the 1st order absorption boundary condition (ABC) in the T-FDTD method to obtain more accurate solutions without increasing number of mesh layers between truncated boundary and scatterer surface. The numerical results of the scatterings for PEC circular and rectangular cylinders show effectiveness of the implement technique.