Use Of Glass Fibers Research Articles

Shear Behavior of Hollow Ferrocement Beam Reinforced by Steel and Fiberglass Meshes

The purpose of this study is to investigate the shear behavior of hollow ferrocement beams of self-compacting mortar reinforced with various types of metallic (steel wire mesh) and non-metallic (fiber glass mesh) reinforcement. The experimental program consists of casting eight ferrocement beams with dimensions of 150×225×2000 mm, with 50 mm of ferrocement thickness and a polystyrene cork core of 50×125 mm. The study parameters were the type of shear reinforcement and the number of layers of wire mesh. The results showed that the ultimate load of the beams reinforced with several layers of the fiber glass mesh (1, 2, and 3) was decreased by (3.27%, 16.52%, and 9.38%) respectively, compared to the beams reinforced with layers of steel wire mesh (1, 2 and 3). The ultimate load of these beams increased by (33.71%, 73.28%, and 122.11%) respectively, compared to the beams without shear reinforcement. Also, the ultimate load of the beams reinforced with layers of welded wire mesh was increased by (38.23%, 107.56%, and 145.09%) respectively, compared to the beams without shear reinforcement. The ductility and toughness of the beams reinforced with several layers of the fiber glass mesh (1, 2, and three) were decreased by (1.68%, 2.11%, 2.68%) and (29.39%, 25.91%, 16.06%) respectively, compared to beams reinforced with several layers of steel wire mesh (1, 2 and 3). The crack propagation was reduced and its number and crack width decreased by using steel wire mesh and fiber glass wire mesh instead of stirrups, especially in beams with two and three layers of wire mesh. The results also showed that the use of glass fiber or welded wire mesh in the reinforcement of hollow beams instead of steel stirrups has a significant effect on the failure load, deflections, crack patterns, and shear stresses, despite the clear preference for beams reinforced with steel wire mesh.

The effect of nanoparticle fillers on glass fiber/poly‐ether‐ether‐ketone prepreg laser absorbance, thermal conductivity and interlayer performance

AbstractAiming at the use of glass fiber reinforced poly‐ether‐ether‐ketone (GF/PEEK) with low laser absorbance in laser assisted tape winding/placement (LATW/LATP), a method for dyeing GF/PEEK prepreg with nanoparticle fillers (NFs) is presented. First, the effects of carbon black (CB) and graphite (G) NFs on composites laser absorbance and reflection pattern were quantified, and the complex refractive index model was derived. Next, the effects of NFs on composites transverse thermal conductivity were tested, and the accuracy of four thermal conductivity prediction models were compared. Finally, the effects of NFs on composites interlayer performance were studied. The optical test results showed that NFs could improve laser absorbance while not changing reflection pattern, and the increase rate of absorbance for CB was higher than for G. As calculated by complex refractive index model, GF/PEEK with 1‐layer thickness could achieve complete laser absorption by addition of either 2.74%CB or 3.78%G. The thermal conductivity test results showed that NFs could improve composites transverse thermal conductivity. The increase rate of thermal conductivity for G was higher than for CB. Among the four prediction model, the Lewis‐Nielsen model had correct prediction regularity and was within 10% predict deviation. Based on this model, the transverse thermal conductivity of GF/PEEK/2.74%CB was 0.557 W/m K, and of GF/PEEK/3.78%G was 0.592 W/m K. The mechanical test results showed that the CB loading ≤4% had little effect on interlayer performance, while the G decreased interlayer performance. Consequently, adding CB at a low loading is a better way to realize GF/PEEK application in LATW/LATP.

Fatigue behaviour of joint-free bridges with steel and GFRP-reinforced ECC link slabs

Engineered Cementitious Composite (ECC) link slabs provide a feasible alternative to leaking expansion joints for improving long-term durability of slab-on-girder bridges. The use of Glass Fiber Reinforced Polymer (GFRP) rebars have become increasingly common for inducing superior chemical resistance in bridge decks in salt-prone locations. Existing literature lacks experimental research on effects of fatigue load on joint-free bridges with ECC link slabs reinforced with GFRP bars. This paper presents results of experimental testing of joint-free bridges with GFRP or steel-reinforced ECC link slabs subjected to static and fatigue (up to 1 million cycles at 4 Hz) loadings. Comparative performance between GFRP and steel-reinforced ECC link slab bridges is described based on load–deflection or moment-rotation behaviour, strain characteristics and crack development in pre-fatigue, fatigue and post-fatigue stages. After 1 million fatigue cycles, the GFRP-reinforced ECC link slab exhibited smaller crack widths and higher deformation capacity while its incorporation provided superior ductility and deformation capability of the full bridge. A finite element (FE) model was also developed using experimental results to simulate load–deflection behaviour of composite deck-steel girder joint-free bridge with ECC link slab subjected to fatigue loading. Parametric FE study showed that increasing mean stress level caused increased composite deck-steel girder deflection while link slab deflection was limited by bridge span deformation.

A low-cost microbial fuel cell based sensor for in-situ monitoring of dissolved oxygen for over half a year

In order to address the need for long-term, in-situ and inexpensive monitoring of dissolved oxygen (DO), a chitin-carrying microbial fuel cell (MFC) based DO sensor was developed using sediment anolyte, which had an extremely low cost of US$12.17 and comparable performance to certain commercial sensors. The MFC based DO sensor had a long lifetime of over half a year with chitin as the fuel, attributed to the syntrophic interactions between fermentative and exoelectrogenic microbes that were well developed for chitin degradation in anaerobic condition with sediment filling in the anode chamber. The use of sediment anolyte introduced hindered diffusion in the porous media, enabling the use of glass fiber as the separator to replace the ion exchange membrane and thus resulting in a much lower cost. Field tests of this MFC based DO sensor were conducted in fresh and saline waters respectively. Excellent performance was achieved with average deviations of <4.5% to three commercial methods of fiber optic sensor (HQ40d, HACH company, USA), Clark type sensor (Pro20i, YSI company, USA) and iodometry. This low-cost MFC sensor also showed a high reliability, with the same response of current generation to different DO levels in random 17-times tests, indicating its great market potentials for in-situ DO monitoring.

Non-linear FE investigation of subsurface tunnel with gfrp protection against internal blast

The contribution of subsurface tunnels in the present time is imperative. However, in the past few decades they have become a target to explosives and terrorist attacks. Considering the strategic importance and susceptibility of tunnels in case of internal explosion, the blast mitigating design has become very critical. In this work, a novel concept involving the use of glass fiber reinforced polymer (GFRP) layer to strengthen the reinforced concrete (RC) tunnel lining against these incidents has been introduced. Metro underground tunnels exposed to internal blast with two different surrounding soil conditions are investigated. The analysis is done using explicit 3D-Finite Element (FE) method. A comparative study towards the damage due to explosion of different trinitrotoluene (TNT) charges is executed. It is observed that the application of GFRP layer reduces the displacement and stress values at key points in tunnel and ground surface under different explosive charges and soil conditions. Also, there is a reduction in the tunnel damage as well as the risk of long-term geotechnical effects in soil. Thus, GFRP may be effectively utilized as an additional layer to improve the resistance of RC tunnel against blast instead of designing an uneconomical rigid structure. Consequently, the present study contributes towards the safety and blast mitigation design of RC tunnels.

Effect of Supporting Base System on the Flexural Behavior and Toughness of the Lighting GFRP Poles

Due to the high risk of common traffic electric poles, the use of glass fiber reinforced polymer (GFRP) material in electric poles has become essential due to its excellent advantages such as high strength to weight ratio, corrosion resistance, and electrical insulation, which keeps people safe. To reduce the accidental effect of street lighting poles on humans, the generated energy during the collision must be absorbed. Experimental and numerical investigations were carried out to identify the efficiency of tapered GFRP electric poles with handle doors using steel sleeve bases until the occurrence of failure. Six full-scale cantilever bending tests were performed to investigate the strength and ductility of the GFRP pole. Moreover, finite element (FE) models were developed using Abaqus software and verified against tests to provide alternative tools instead of lab experiments. An extensive parametric study was carried out to predict the effect of the GFRP pole wall thickness, base plate geometric (length, diameter, and wall thickness), electric cable hole diameter, material properties, and base sleeve geometric (length and wall thickness) on the toughness of the GFRP pole. Based on the results of the load–displacement (P–Δ) curves, the flexibility of the GFRP poles was directly proportional to their length and the local buckling failure often occurred at the handle door. Strengthening the zone of the handle door using a steel ring was investigated to prevent the local buckling failure at this part. However, the wall thickness of the GFRP pole, base sleeve height, base plate dimensions, and base plate material properties were the most effective parameters to enhance accidental energy absorption through large deformation kinematics. The base sleeve thickness had a slight direct effect on the ductility and toughness of the GFRP pole.

Numerical investigation on strengthening steel beams with web openings using GFRP

This study presents the first investigation into the use of glass fiber reinforced polymer GFRP to strengthen steel beams with web openings. Based on previous research about the strengthening of steel beams with web perforation using carbon fiber reinforced polymer (CFRP) conducted by one of the contributing authors of this paper, it was decided to investigate the ability of pultruded glass fiber reinforced polymer, which is less expensive than CFRP materials, to strengthen single rectangular web openings of steel beams. The previous published experimental test was used to validate the proposed numerical model developed with the finite element software ABAQUS, capable of acquiring important phenomena such as debonding between FRP and steel material. The validated simulation was then used to operate a parametric study involving four proposed GFRP strengthening techniques and three distinct pultruded GFRP product thicknesses to reinforce the same steel beam used in the earlier experimental test, having a single rectangular opening shape in two separate positions along the span. From these numerical models, an adequate GFRP strengthening arrangement was found and the possibility of using low-modulus FRP materials rather than the more expensive high-modulus FRP materials for strengthening steel beams with web penetration was confirmed.

Durability assessment of GFRP rebars in marine environments

Technologies developed over the last two decades have facilitated the use of glass fiber reinforced polymer (GFRP) bars as internal reinforcement for concrete structures, specially in coastal environments, mainly due to their corrosion resistance. To-date, most durability studies have focused on a single mechanical parameter (tensile strength) and a single aging environment (exposure to high alkalinity). However, knowledge gaps exists in understanding how other mechanical parameters and relevant conditioning environments may affect the durability of GFRP bars. To this end, this study assesses the durability for different physio-mechanical properties of GFRP rebars, post exposure to accelerated conditioning in seawater.Six different GFRP rebar types were submerged in seawater tanks, at various temperatures (23°C, 40°C and 60°C) for different time periods (60, 120, 210 and 365 days). In total six different physio-mechanical properties were assessed, including: tensile strength, E-modulus, transverse and horizontal shear strength, micro-structural composition and lastly, bond strength. It was inferred that rebars with high moisture absorption resulted in poor durability, in that it affected mainly the tensile strength. Based on the Arrhenius model, at 23°C all the rebars that met the acceptance criteria by ASTM D7957 are expected to retain 85% of the tensile strength capacity.

Use of Glass Fiber Reinforced Gypsum (GFRG) as a Sustainable and Efficient Alternative in Housing in India

Use of Glass Fiber Reinforced Gypsum (GFRG) as a Sustainable and Efficient Alternative in Housing in India

Effect of Alkali-Resistant Glass Fibers and Cement on the Geotechnical Properties of Highly Expansive Soil

The main objective of this study was to evaluate the use of glass fibers and cement as stabilizing agents for highly expansive soil. Fibers with two aspect ratios (12 and 30 mm in length) were added as percentages of the soil’s dry weight (0.5%, 0.75%, 1%, and 1.5%), the cement was added in two percentages by dry weight soil (2% and 6%). Sixteen groups of treated soil specimens were prepared and subjected to laboratory tests—unconfined compressive strength (UCS) after curing (0, 7, 14, and 28 days), swelling percentage, and California bearing ratio (CBR). Interactions at the interface between the fiber surface and the soil matrix were analyzed by scanning electron microscopy (SEM). Also evaluated was effect of fibers on the design and performance of cement-stabilized subgrade layers according to the Mechanistic-Empirical Pavement Design Guide (MEPDG) to compare the performance of flexible pavement sections modeled using default values and laboratory-established soil properties for inputs. Results indicated increases in UCS and soaked CBR and decreases in swelling tendency. The 6% cement/1.5% short fiber mixture resulted in a significant improvement in expansive soil properties over other mixtures.

Development of a maturity method for GFRC shell concretes with different fiber ratios

The use of glass fiber reinforced concrete (GFRC) in the construction industry is increasing due to its mechanical and physical properties. Waiting time of concrete in the mold and the removal of the mold at the right time are important in terms of strength. In conventional concretes, maturity models are widely used as a non-destructive method for early strength estimate. In this study, it is aimed to develop an estimate model of flexural and compressive strength in GFRCs using the maturity index method. In this context, glass fiber reinforced concretes were produced at the rates of 0%, 1%, 2% and 3%. Calcined kaolin and acrylic polymer were used as modification materials in the mixtures. Properties such as compressive, flexural, hardness, and shrinkage of specimens were investigated at different ages. The maturity-strength relationships of mixtures at different ages were examined by weighted maturity and Nurse-Saul methods. At the end of the study, two new models were developed to estimate the compressive and flexural strengths of GFRCs, taking into account all the data. The suggested models have been confirmed by examining them on all mix-age groups and comparing them with the literature.

Seismic Performance of Hybrid Corrosion-Free Self-Centering Concrete Shear Walls

Reinforced concrete (RC) walls are extensively used in high-rise buildings to resist lateral loads, while ensuring an adequate level of ductility. Durability problems, including corrosion of conventional steel reinforcements, necessitate exploring alternative types of reinforcement. The use of glass fiber reinforced polymer (FRP) bars is a potential solution. However, these bars cannot be used in seismic applications because of their brittleness and inability to dissipate seismic energy. Superelastic shape memory alloy (SMA) is a corrosion-free material with high ductility and unique self-centering ability. Its high cost is a major barrier to use in construction projects. The clear advantage of utilizing both SMA and FRP to achieve durable self-centering structures has motivated the development of a composite SMA-FRP bar. This paper investigates the hybrid use of FRP bars and either SMA bars or composite SMA-FRP in concrete shear walls. An extensive parametric study was conducted to study the effect of different design parameters on the lateral performance of hybrid RC walls. The seismic behavior of the hybrid walls was then examined. The hybrid walls not only solved the durability problem but also significantly improved the seismic performance.

Experimental investigation on the use of glass fiber reinforced polymer reinforcement in hollow‐core circular concrete columns

AbstractThis paper presents the results of an experimental investigation on the behavior of glass fiber reinforced polymer (GFRP) bar‐reinforced hollow‐core (GFRP‐HC) circular concrete specimens under concentric, 25 mm and 50 mm eccentric axial loading and four‐point bending. The main parameters investigated include the type of reinforcing bars, pitch of the helices and loading conditions. The test matrix of this study consists of 12 specimens, among which nine specimens (850 mm high) were tested under concentric and eccentric axial loading and the remaining three specimens (1500 mm long) were tested under four‐point bending. The specimens were circular in cross‐section with an outer diameter of 214 mm and an inner circular hole diameter of 56 mm. The experimental results showed that, for the similar amount of reinforcement, steel bar‐reinforced hollow‐core (steel‐HC) specimens sustained higher loads than the GFRP‐HC specimens under different loading conditions. Also, the steel‐HC specimens achieved higher ductility than the GFRP‐HC specimens under 50 mm eccentric axial loading and four‐point bending. However, under concentric and 25 mm eccentric axial loading, the GFRP‐HC specimens achieved higher ductility than the steel‐HC specimens. The close pitch of the GFRP helices significantly enhanced the load carrying capacity and ductility of the GFRP‐HC specimens.

Life cycle assessment of bio-composite laminates. A comparative study

The use of glass fiber reinforced plastics is steadily increasing in the aerospace industry for aircraft interiors. However, the glass fiber reinforced plastics, although provide a robust solution they have many issues concerning their environmental friendliness. An alternative environmentally friendly solution for aircraft interiors is the use of bio-composites. Bio-composites used in this kind of applications are made of natural fibers as reinforcement and the use of bio-resins as matrix material. In the present study a life-cycle assessment approach is applied to selected bio-composites scenario and the comparison were made against the currently used glass fiber reinforced plastics. Results show the use of flax fiber reinforced materials seems to have lower environmental impact.

Implementation and Characterization of a Laminate Hybrid Composite Based on Palm Tree and Glass Fibers.

In this work, laminated polyester thermoset composites based on palm tree fibers extracted from palms leaflets and glass mats fibers were manufactured to develop hybrid compositions with good mechanical properties; the mixture of fibers was elaborated to not exceed 25 vol.%. Samples were prepared with a resin transfer molding (RTM) method and mechanically characterized using tensile and flexural, hardness, and impact tests, and ultrasonic waves as a non-destructive technique. The water sorption of these composite materials was carried out in addition to solar irradiation aging for approximately 300 days to predict the applicability and the long-term performance of the manufactured composites. Results have shown that the use of glass fibers significantly increased all properties; however, an optimum combination of the mixture could be interesting and could be developed with less glass sheet and more natural fibers, which is the goal of this study. On the other hand, exposure to natural sunlight deteriorated the mechanical resistance of the neat resin after only 60 days, while the composites kept high mechanical resistance for 365 days of exposure.

Comparative Study of Damping on Pultruded GFRP and Steel Beams.

The use of glass fibre reinforced polymer (GFRP) composites in civil engineering structures has seen considerable growth in recent years due to their high strength, low self-weight, and corrosion resistance, namely when compared to traditional materials, such as steel and reinforced concrete. To enable the structural use of GFRP composite materials in civil engineering applications, especially in footbridges, it is necessary to gather knowledge on their structural behaviour, particularly under dynamic loads, and to evaluate the ability of current design tools to predict their response. In fact, excessive vibration has a major influence on the in-service performance (comfort) of slender structures as well on their service life. The use of composite materials that combine high damping capacity with relatively high stiffness and low mass can provide functional and economic benefits, especially for footbridges. This paper aims to investigate the dynamic behaviour of GFRP free-supported beams to evaluate their modal characteristics (frequency, damping, and modal shape). To assess the benefits of using a structure made of pultruded GFRP rather than a conventional material—steel, a comparative analysis between the dynamic characteristics of GFRP and steel beams is performed. To specifically address material damping and to minimize the interference of the boundary conditions, the beams are tested in a free condition, resting on a low-density foam base. The results show that the damping capacity of GFRP is much higher than that of steel, as the measured damping factor of GFRP is five times higher than that of steel for the same boundary conditions and similar geometry. Furthermore, the fact that the frequencies of the tested specimens resemble for the two different materials highlights the perceived damping qualities of the polymer-based composite material. Finally, an energy method for evaluating the influence of the scale factor on material damping is applied, which made it possible to infer that the damping varies as a function of frequency but is not explicitly affected by the length of the specimens.

The Influence of Glass Fiber and Milled Glass Fiber on the Performance of Iraqi Oil Well Cement

The reinforced fiberglass in cement slurry reflects the effect on its properties compared to usual additives. Fiberglass is typically used in cement slurry design for one or another of the following goals: (Earth earthquake, bearing storage, and with differential stresses, to enhance cement durability and increase its compressive strength). The main goal is to use glass fiber and ground fiberglass to improve the tensile strength and moderate compressive strength significantly. On the other hand, the use of glass fibers led to a slight increase in the value of thickening time, which is a desirable effect. Eleven glass fiber samples and milled glass fiber were used to show these materials' effect on Iraqi cement with (0.125, 0.25, 0.5, 0.75, 1, and 2) % of cement weight. Those tests used to study cement slurry‟s following properties were compressive strength, thickening time, rheology properties of free water, filtering, and density. These evaluations showed that slurries with less than 1% fiber content gave a higher compressive strength than a sample containing more than 1% glass fiber. However, the slurry mixed with equal or less than 1% milled glass fiber is higher compressive than the sample mixed with more than 1% milled glass fiber. So the optimal concentration for glass fiber is less than 1% by weight of cement (BWOC); either for milled glass fiber, it is less or equal to 1% BWOC. Both materials contributed to increasing the compressive strength of the cement. However, attention must be paid to the idealThis work is licensed under a Creative Commons Attribution 4.0 International License.&#x0D; concentration that should be added during the cement slurry preparation because if we use these two materials carelessly for the ideal concentration, this leads to the collapse and bombardment of the resistance of the cement rock. In other words, the collapse of cement resistance and causing problems during the cementing process.

Investigation on the effect of functionalization of single-walled carbon nanotubes on the mechanical properties of epoxy glass composites: Experimental and molecular dynamics simulation

In recent decades, polymer composites are widely used in industry due to their good mechanical properties and their low specific weight. Also, the use of glass fibers and carbon nanotubes can strengthen and improve the mechanical performance of the polymer due to their good mechanical properties. In this study, incorporated glass/epoxy nanocomposite with carbon nanotubes (CNT) samples were fabricated using a hand lay-up process, and the effect of addition functionalized Single-Walled Carbon Nanotubes (F-SWCNT) with COOH and non-functionalized SWCNT was investigated. The tensile strength, elastic modulus, bending strength was obtained experimentally using SANTAM-STM50. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to investigate the phase and morphology of the fibers. The mechanical properties results showed that the highest elastic modulus and tensile strength are obtained for the sample reinforced with F-SWCNT which increased by 32% and 10%, respectively in comparison with pure epoxy. Also, the obtained results of the bending test indicate that the highest flexural modulus and the highest flexural strength are related to the sample reinforced with functionalized carbon nanotubes which are 16.9 GPa and 381.39 MPa, respectively. Then, the mechanical performance of the reinforcement in the epoxy matrix and the failure mechanism was monitored using SEM images. Finally, reinforced epoxy nanocomposites with functionalized and non-functionalized SWCNT were simulated using Molecular Dynamics (MD) simulation to examine the agreement with the trends of experimental results. The MD obtained results showed that the most appropriate mode of dispersion occurs when functionalized carbon nanotubes are used. Also, it was observed that the elastic modulus of incorporated nanocomposites with F-SWCNT increased by 17% compared to non-functionalized SWCNT which shows the agreement with the trends of experimental results.

Behaviour and Strengthening Methods of Tall Slender Columns in Earthquake Conditions

Reinforced concrete buildings are normally designed and constructed with well-defined vertical column supports which are able to withstand both vertical and lateral loadings. In the case of high columns there is a risk of instability due to its slenderness caused by the higher apex ratio (measured by its height in relation to the width). This is compounded by having such buildings located at medium to high seismic risk zones, where lateral dynamic loadings can occur. This research paper focused on how such slender reinforced concrete columns will behave under earthquake loading conditions, and highlights some innovative ways to strengthen the column capacity to withstand both vertical and lateral loadings. Besides the conventional ways to provide diagonal or lateral bracings, the use of glass fibre reinforced polymer (GFRP) as an alternative material for retrofitting tall slender reinforced concrete columns are presented here. The new method includes spraying of the GFRP onto the external surfaces of the columns and also incorporate the GFRP bars as additional reinforcement into the concrete columns. Both methods proved to improve the durability and strengthen the tall reinforced concrete column. This study shows the ability of the new method of amelioration of the slender reinforced concrete columns to increase their stability during seismic activity.

Degradation of Glass Fiber Reinforced Polymer (GFRP) Material Exposed to Tropical Atmospheric Condition

Fibre reinforced polymers (FRPs) have emerged as popular materials for structural application in recent decades due to numerous of advantages. Despite the growing body of research on the use of glass fibre reinforced polymers (GFRP) composites in repairing and retrofitting the important structures such as oil and gas pipelines, the lack of comprehensive data on the long-term degradation mechanism for these materials is still impeding their widespread use in open-air structures repairs particularly in tropical climate locations such as Malaysia. Therefore, this paper presents an experimental investigation to determine the influence of tropical atmospheric condition on tensile properties of the GFRP. In this study, a set of GFRP samples were fabricated using epoxy resin as polymer matrix and woven E-glass fibres as reinforcing materials. These samples were exposed to tropical atmospheric condition in Malaysia for a period of four months. Tensile test was carried out for each sample before and after four-months period of exposure. The experimental tensile test results recorded a 15% reduction in tensile strength after 4 months of exposure as compared to its original strength. Further, the dominant failure mode of the exposed sample was characterized with longitudinal splitting of the fibres without completely breaking out. Overall, the tropical atmospheric condition has a noticeable impact on the GFRPs tensile strength degradations over the exposure duration.