Replace Steel in Bridge with GFRP

After extensive laboratory research on glass fiber reinforced polymer (GFRP) as internal reinforcement of concrete, graduate students at the University of Miami are working with Moss Construction Management to substitute steel deck reinforcement with GFRP rebars in the construction of the “Fate Bridge” on campus in an effort to combat future corrosion problems. To date, GFRP has proven to be an effective internal reinforcement for concrete structures as an alternative to steel due to its magnetic transparency, corrosion resistance, durability, high strength-to-weight-ratio, and life expectancy. GFRP is also about four times lighter than steel.

GFRP bars, replacing standard steel rebars for concrete reinforcement, have been laid out on the bridge deck. The next step is casting the concrete. This decreases the amount of labor needed to complete the same tasks in construction sites. This also makes the use of GFRP more advantageous than steel for the bridge project, and it could decrease concrete usage in the future.

Lead by their advisor, the students are installing a state of the art monitoring system with two types of gauges embedded in concrete and directly attached to the reinforcing GFRP and steel rebars in the bridge deck and superstructure. The Vibrating Wire Strain Gauges are designed to measure strains on the steel or GFRP internal reinforcement of certain concrete elements in the bridge. These gauges consist of a steel wire tensioned between two mounting blocks attached to stainless steel pads which are epoxy bonded to the rebars. The Concrete Embedment Strain Gauges are designed to measure strains directly by embedment in concrete using the vibrating principle with a steel wire compressed between two blocks.

This article is from glass fiber chopped strand mat manufacturer WB COMPOSITES

Fiberglass Is Still Material of Choice for Most Boatbuilders

1. What are the various marine manufacturing segments?

When break the industry down into three separate segments: engines, vessels and accessories. There are four different types of engines used depending on the type of vessel. Accessories include anchors, tubs and showers, which can be cultured marble or fiberglass products. The vessel, or boat segment, is where composites really fit in. The vessels could be pontoons, cruisers (a joy ride, comfortable vessel), speed boats (built for things like water skiing to 100 mph races) and yachts.

2. The trends between carbon and fiberglass composites

Right now, the majority of the industry continuing to use fiberglass over carbon composites because it offers high quality and you can get it for lower cost. However, when you look at racing boats, people will look at carbon because weight is the biggest factor. But when looking at the general boat manufacturing industry that sells to families or fishermen, the most economical solution is still fiberglass.

3. Is there one segment of the marine industry that uses composites more?

Pontoons are usually made from aluminum, and you’ll find a mix among small fishing boats, but personal watercrafts such as cruisers and yachts are primarily fiberglass. You may find two or three manufacturers who use aluminum, but by and large, composites are the material of choice.

This article is from fiberglass chopped strand mat manufacturer zccyfiberglass.com

Fibre-reinforced composite materials Introduction

Fibre-reinforced composite materials have gained popularity in high performance products that need to be light-weight yet strong enough to take harsh loading conditions such as in transport (cars and body panels, bumper, engine components, fuel lines), aerospace (bulk head and floor, landing gear door, rotor blade, satellites structure, cargo liner) . Boat decking (Boat hull, submersible pressure hull, propeller, shaft). Engineering (pipe system, power transmission drive shaft storage tank, air duct work, pressure vessel), Sports (bike frames, canoe, finishing rods, skipoles, racquets surf band). Health (Artificial teeth), Domestic purpose (shower unit, furniture, sanitary wear, bath.

The matrix materials can be introduced to the reinforcement before or after the reinforcement material is placed into the mould cavity or on the mould surface. The moulding methods can be by transfer moulding, press moulding, pultrusion moulding, vacuum bag moulding, filament winding, casting, centrifugal casting, wet lay-up, compression moulding, thermoplastic moulding, hand lay-up, spray lay-up.

The use of glass fibre to fill polyester has been reported, Polyester was reinforced with glass fibre and it was found that the increase in specimen size geometry led to an increase in energy at break, peak load, critical strain energy release rate and critical stress.

Woven roving glass fibre and chopped strand glass fibre have been utilized successfully in preparing polyester composites. The tensile strength and tensile modulus of the polyester composites were found to increase with increase in number of plies. The tensile strain of the prepared composites increased with increase in number of plies and further addition of plies decreased the tensile strain.

The use of glass fibre woven roving and chopped strand mat for the automobile industry will greatly reduce the weight which when used in fabricating the entire car body will result to a decrease in fuel consumption and increase in the speed of the car.

Material of Glass Fiber Chopped Strand Mat

The Glass used commonly for GRP is a calcium-alumina borosilicate with an alkali content of less than one per cent. It is commonly known as ‘E’ type glass, since it was originally developed for use in electrical insulation systems.

Glass Fibers are produced by running molten glass from a direct melt furnace into a platinum alloy bushing containing a large number of small holes, from each of which a glass filament is drawn. Filaments for commercial use are normally between 9 and 15 microns in diameter. The filaments are “dressed” with an emulsion before being gathered into fibres. The fibres are remarkably strong-the tensile strength being particularly high. They also exhibit good chemical and moisture resistance, have excellent electrical properties, are not subject to biological attack and are non-combustible with a melting point around 1500oC-all excellent qualities in a plastic reinforcement.

The glass fibers can be used in a variety of ways-chopped into short lengths(“chopped strands”); gathered together into loosely bound ropes (“rovings”); woven into a variety of fabrics, produced from yarn made by twisting and doubling continuous strands. In the UK, the most widely used Glass Fiber material is chopped strand mat, which consists of glass strands chopped together in short lengths (approx. 50mm) and held together in mat form by a polyvinyl acetate or polyester binder. The mat is available in a range of weights, from 225gm2 to 1200gm2, and is a useful general purpose reinforcement.

Production Machine of Fiberglass Chopped Strand Mat -Drying Oven

The drying-oven is composed by a tunnel thermally isolated and furnished with a conveyor belt.

     The drying-section is heated by the direct-gas-fired system.

     The dryer is divided in zones. Each zone has a circulating fan and separate          temperature controls.

1. Conveyor Belt

      The belt of the conveyor is a special stainless steel wire mesh, of the upper side, the mesh is supported by a series of rollers equipped with ball-bearings (outside of the oven).

      Cleaning brushes and cleaning burners are mounted on the conveyor belt.

      A belt guiding and tension system is provided. 

2. Ventilation

      Over and under the upper belt section are mounted special air-distributing cases. The upper ones are blowing and the under ones are sucking. 

      They are providing the rational distribution and the ventilation of the air all over  the surface of the fiberglass chopped strand mat. under the sucking cases are mounted air-filters of mat or of veils.

      The motion of the air in each sector is provided by heavy duty ventilators with special shovels.

      The construction of the ventilators and the air popes for the blowing and  sucking and the cases is realized in matter to make easily the cleaning operations.

3. Exhausted air

      In the sections, exhausters will provide for the exchange of the circulating air.

4.  Air-Heating

      Each section is furnished with his own gas burner. After passing the material to dry, the hot air is sucked by the lower cases and therefore returns in cycle.

      The fresh air is sucked by holes with filters, opportuned placed on the sucking pipe.

5. Control Unit of The Burning and The Temperature

       Each burner is furnished with a set of controls for the temperature regulation. 

       Each set is composed by :

Temperature regulator

The thermo states of max. and min.

The timer for the burning cycle

The control U.V, photo cells

The servo control  for the flame modulation  

      For the circulating, the exhaust and the combustion air are foreseen control units of the pressure.

      All these units will be placed into a control-panel.

6. Thermal insulation cleaning and accessibility

      The drying tunnel is composed by a strong frame of iron U-profiles, covered with insulating panels, the hole structure is dis-assemblable.

      By planning the structure we have considered the thermal expansion and             provided for the necessary. the insulating panels are manufactured with special iron sheets. 

      They are filled with glass wool.

      Along the sides of the oven, at a suitable distance, are mounted inspection          doors.

      The distribution cases are furnished with openings to make easy the cleaning        and maintenance.

Binder Applicators System For Fiberglass Chopped Strand Mat

Powder Binder

The glass fibers are transferred from the conveyor belt of the forming section to another conveyor belt for the binder application. The forming belt will remain clean and dry everytime. Binding with powder is composed by 2(two) powder-binder-applicators, and a series of sprays of demineralized (distilled) water.

Both sides of the mat, the upper and the lower-one, are lightly sprayed with distilled water, that operation is necessary or a better adhesion of the binder. The special powder-applicators warrant an optimal distributing .

Between the two applicators a vibrator is applied providing that the powder is also passing to the lower side of the mat.

Binding with Emulsion

The curtain system used warrants a perfect distribution of the binder. The excess of binder will be recovered by a special sucking system.

This system pulls the air through the fiberglass chopped strand mat and a part of the binder will be taken off. By that mater the binder will be distributed uniformly and the excess of binder eliminated. 

Obviously the binder will be re-employed after special filtering which separates the air and the dirt.

The binder is stored in containers in the mixing room and conveyed at low pressure by a pipeline to a small tank near the mat-plant.

A special device maintain the level of the tank constant. Also the recovered binder will be conveyed to the tank. A pumping system conveys the binder from that tank to the curtain distribution system.

Fiberglass Chopped Strand Mat Wets out with Epoxy

Fiberglass Chopped strand mat, in fabric form, it is made up of 1"-2" long fiberglass strands that are randomly oriented and typically held together with a styrene-soluble binder that acts like glue connecting the fibers. The binder is designed to dissolve upon contact with styrene in polyester resin or vinyl ester resin. Once dissolved, the fabric softens, allowing it to drape around curved shapes. It comes in a variety of weights between .75 oz to 3 oz per square foot. The most popular weights are .75 oz and 1.5 oz.

In the US, fiberglass chopped strand mat is nearly always sold or specified in ounces per square foot. This is different than fiberglass cloth and fiberglass fabrics with oriented fiber layers (including woven cloth, stitched biaxial & triaxial fabrics, and the like). These are designated in ounces per square yard. When the mat is attached to any of these fabrics (as in fabmat or biaxial with mat), the combined fabric is often called out in fabric weight. An example of this is our 738 Biaxial Fabric, which is a 1508 biaxial fabric with mat. This means 15 oz per sq yard of biaxial fabric plus an attached 0.8 oz per sq foot layer of mat.

Can epoxy be used to wet out chopped strand mat? The answer is yes. The fiberglass strand in mat wets out with epoxy, but the binder holding things together does not dissolve. (It does get put into suspension and is sealed in the cured epoxy.) This undissolved binder causes the wet-out mat to remain a bit stiff compared to wet out with a styrene-based resin. For gently curving or flat projects like cabin soles or plywood decks, mat and epoxy should work fine. The fabric does not wet out perfectly clear with epoxy. Wet-out clarity of mat with epoxy varies somewhat with different suppliers, but none of them wet out as clear as a good 4 oz or 6 oz fiberglass cloth.

The texture of the chopped strand mat is quite rough given its random fibers (many of which come loose when epoxy is applied). Mat requires a number of coats of epoxy to fill the profile at the surface. Release Fabric can be applied over the freshly wet-out mat to compress the fibers and minimize the need for many of the buildup coats. Using release fabric in this way will result in a much smoother surface, and if you are going to allow the epoxy to cure before continuing, the surface is ready for buildup coats of epoxy or fairing putty after the release fabric is removed.

Plastic sheeting can also be used over the still uncured epoxy and mat to compress the fibers. Trapped air bubbles can be removed by piercing or slitting the plastic over the bubble before the epoxy begins to cure. If the plastic was clean when it was applied, you can pull the plastic after the epoxy cures to a hard gel and apply epoxy fairing putty or buildup coats of epoxy later the same day. If you allow the epoxy to cure hard before pulling the plastic, be sure to sand the surface completely dull before applying more epoxy.

When choosing chopped strand mat to be used with epoxy, look for mat that is soft and pliable. Some forms are quite stiff and may cause problems wetting out with epoxy. Stiff mat is often older stock and the fibers may take more time to wet out with epoxy.

Fiberglass Pipe Production Process

GRP pipes are produced by either the Continuous Filament Winding or by the Reciprocal Helical Winding process. Both are considered as filament winding machines, which is the process of impregnating a number of glass reinforcement with resin, then applying the wet fibers onto a mandrel in a prescribed patter.

Continuous Filament Winder: A continuous winder is composed of a continuous steel band supported by beams which form a cylindrically shaped mandrel. The beams rotate, friction pulls the band around and roller bearings allow the band to move longitudinally so that the entire mandrel continuously moves in a spiral path toward the end of the machine.

As the mandrel moves, raw materials, like glass fibers, resin, aggregate (if needed) and surface veil are metered on in precise amounts under the direction of a programmable logic controller (PLC) and computer (PC). After pipe is cured a synchronized saw unit cuts the pipe to the proper length.

Continuous winding process is considered as the most efficient, since once pipe production starts, as described above, the production process continues and would only stop at the completion of full order. This process is considered continuous since it does not hold and resume at the completion of each pipe or pipe layer.

Reciprocal Helical Winding: is the process where the glass rovings, continuous roving specifically, passes though a resin bath for resin impregnation. Resin bath and glass directing comb are placed on a carriage that is driven back and forth at a very well controlled linear speed. Fiberglass, pre-impregnated with resin, are winded on steel mandrel that is rotating at determined RPM. The synchronization of carriage linear speed as well as the mandrel RPM determines the angle of which roving are winded on the mandrel, which is considered to be the glass winding angle, that is redetermined depending on the pipe requested property. For this reason, both the mandrel RMP and carriage speed are very well controlled by a computer program.

In this process, winding progress is in stages, were multiple linear movement of carriage would produce one layer of pipe thickness, and pipe thickness is composed of multiple layers, depending on required total thickness.

   

For all processes, GRP pipes are made from many layers, the main layers are:

- Inner liner, which is rich with resin and is to provide chemical resistance to the pipe and well as well as smooth inner surface. Inner liner thickness that could reach up to 2.5 mm

- Structure layer, which is forming the majority of pipe thickness. Pipe mechanical strength is mainly achieved by the structural layer.

- Outer liner, which is as well rich with resin and is to give environmental protection to the pipe thickness.

GLASS FIBER REINFORCED PIPES INTRODUCTION

What is GRP PIPES? Glass Reinforced Pipes (GRP) Pipes are made from glass fiber reinforcements that are embedded in cured thermosetting resin. GRP Pipes may contain aggregate granular.

The selection of proper material as well as material composition depends on the pipe required properties and as well as designed performance characteristics.

GRP pipes were introduced since 1948. Since then GRP invaded the market due to its corrosion resistance capabilities and were selected as alternative to steel and stainless steel pipes.

GRP pipe line expanded to include applications of high pressure, as well as big range of diameters reaching up to 4000 mm.

GRP pipes combine the benefits of durability, strength, and corrosion resistance; moreover, they offer great design flexibility with the possibility to customize the pipe design in a wide range of properties, the same is applicable to providing a wide range of different fittings profile and shape.

Materials:  

GRP pipes consist of:

Glass Fiber Reinforcement: the mechanical strength of GRP pipes depends on the amount, type and arrangement of glass reinforcement.

The common glass types used in the GRP pipes are:

Fiberglass Reinforcements are available in different forms:

Continuous Roving, consisting of bundled, untwisted, strand. It provides excellent mechanical properties.

Fiberglass Chopped Strand Mat, consisting of chopped strands held together with binder. It is used to provide multidirectional reinforcement in pipes as well as fittings

Surface Veil, are of light weight that allow high resin content layers, that helps in improving the environmental resistance of pipes and fittings, in addition to smooth surface.

 

Resins: only thermosetting resins are used in the production of GRP pipes. Thermoset resin are polymeric resin cured by heat or/and chemical additives.

Resins could be of two types:

- Polyester, such as Isophthalic, that is commonly used to manufacture large diameter pipes used for conveying water and sewage. Vinyl ester, is another polyester, but have increased corrosion resistance and is commonly used to convey aggressive fluids such as acids.

- Epoxy resins are commonly used to manufacture small diameter pipes to convey water, hydrocarbons, diluted acids, …

- Additional components might be used in the GRP pipes such as: Silica Sand, Organic Peroxides catalyst, hardeners and accelerators …Fiberglass Chopped Strand Mat

Globle Market Trend of FRP Pipe 2015-2020

According to latest research, the global FRP pipe market size in terms of value is projected to grow at a CAGR of 3.5% between 2015 and 2020 to reach $4 billion by 2020.

The global FRP market, has witnessed a strong growth in the past few years. This growth is estimated to continue in the coming years due to increasing demand from Asia-Pacific. There are continues increasing demand from end-user industry from the emerging economies, such as China, Brazil and India and also from Middle East region. These are the major drivers as per the current market dynamics. Also, such demand is backed by increasing industrialization and government awareness towards water and waste water treatment. The superior mechanical and anti-corrosion properties, low conductivity, and longer lifecycles make FRP pipes a natural choice both for various applications. The North American and Rest of the World’s FRP pipe markets are expected to grow at a CAGR of 2.6-2.8% and 3.2-3.5% during 2015-2020.

Currently, Asia-Pacific is the largest consumer of FRP pipes and it will continue to drive the market. The major drivers of Asia-Pacific FRP pipe industry are growing investment towards urban infrastructure development, establishment and upgrade of airports, capacity expansion in petrochemical plants, and establishment of power plants. Increasing demand from replacement of existing metal pipe in oil and gas exploration activities to get rid of corrosion problems also drive the FRP pipe market Asia-Pacific region. Among all the countries in this region, China, Japan and India are important consumers of FRP pipe. China held the largest share in the regional consumption in terms of volume in 2014. The market size in terms of volume is comparatively low in the RoW, but is estimated to have a developing CAGR between 2015 and 2020 due to the increasing market share of Brazil and countries from Middle East region.

Almost 85% of the total FRP pipe demand in 2014 was from oil & gas, retail fuel, water & wastewater sewage, and chemical industries. This was due to their physical and mechanical properties such as superior anti-corrosion properties, low conductivity, and longer lifecycles of FRP pipes. A major application industry that uses FRP pipes is Oil & Gas which contributes major market share.

Asia-Pacific and European regions are the most active markets in terms of strategic initiatives, owing to their emerging and mature market demands, respectively. The superior end-user industry growth, amplified local manufacturing, and increased number of domestic players in vertical market segments, such as industrial applications in the Asia-Pacific region can be the important drivers in terms of consumption of the FRP pipes.

This article is from professional fiberglass chopped strand mat manufacturer WB Composites fiberglass website.