Textile Reinforced Concrete: A new Age Construction Material

Abstract

Textile reinforced concrete (TRC) is an innovative building material especially suited for effective maintenance of existing structures or manufacturing new lightweight precast members or as secondary building material as an aid in main building material. Textile reinforced concrete is also a new age construction material where the basic difference lies in the material used for reinforcing. Under traditional methods, the steel reinforcing bars are used with the concrete but here the steel bars are replaced by textile materials. Steel has been known to corrode over time and it is where the textile reinforced concrete has been successful in filling the gap. It is much more flexible and versatile and has thus found requirements of varying and innovative nature in the construction industry. The textile reinforcement is the force behind an enhanced tensile strength, ductility and other features to the TRC materials. We discuss the fabrication methodology used, application potential of TRCs across a range of industries, advantages and drawbacks including the future prospect of such an innovative material.

Textile Reinforcement Materials

Textiles have replaced steel reinforcement bars primarily due to the inherent weakness of steel to prevent corrosion but also due to the superior strength of the chosen textile type. The material chosen is typically based on the strengths and superior properties inherent to that material. Corrosion and temperature resistance, bond quality, cost of material and environmental impacts are some of the factors responsible for selection.

Some of the materials being used are:

AR-Glass

Glass fibres come from the family of inorganic non-metallic raw materials. Glass fibres are produced in a process in which molten glass is drawn in the form of filaments. The material used to produce AR-glass is primarily silica sand and the addition of zircon for alkali resistance. The raw material combine undergoes a melting process between 1250 to 1350 degree Celsius and molten glass if formed.

Fibres are produced after fiberization process and fibres are produced through a wet-spinning process. Fiberization is the rapid cooling to prevent crystallization and formation into glass fibres. A coating is then applied during sizing of glass fiber to obtain a specified surface wetting and bonding of the filaments.

Basalt

Basalt fiber is a material made from extremely fine fibers of basalt, which is composed of the minerals plagioclase, pyroxene, and olivine. These are mineral fibres extracted from volcanic rock. It is similar to fiberglass, having better physicomechanical properties than fiberglass, but being significantly cheaper than carbon fiber. It is used as a fireproof textile in the aerospace and automotive industries and can also be used as a composite to produce products such as camera tripods.

It does not contain any additive in terms of raw materials, and as a result, involve simple and conventional processes and equipment which is said to be cost effective.

Carbon

Carbon fibers  (alternatively CF, graphite fiber or graphite fiber) are fibers about 5–10 micrometers in diameter and composed mostly of carbon atoms. Carbon fibers have several advantages including high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion. 

Carbon fibres are chemical fibres and the element used to produce carbon fiber is called polyacrylonitrile, an organic polymer produced by a polymerization process.

Following a similar process as AR-glass fibers, this also undergoes wet-spinning to fabricate chemical fibres which are then drawn into filaments. Through an oxidation process, non-carbon atoms are removed, resulting into the atoms being thermally stabilized.

Plastic

Experimental studies are being conducted all over the world to replace steel with plastic as a reinforcement material in concrete. Scientific studies have revealed that recycled plastic can be used as a reinforcement material and a considerable saving of CO2 emissions is achieved. Recycled polypropylene plastic is used as the reinforcement material for the studies done in the recent past. This material can be used to build footpaths and precast elements such as drainage pits and concrete sleepers.

Fabrication Methods

There are many fabrication methods particularly suited to the textile meshes and based on the concrete shape to be formed, multiple methods can be deployed. Open-grid structure and displacement stability are favored in order to allow for adequate penetration of a cementitious matrix, while ensuring a relatively constant woven mesh structure in composite form.

Applications and Potential

Superior material characteristics have resulted in glass and fiber carbon reinforcements being used across numerous fields of application in the building and secondary material market. The possible fields of application are:

·         Ventilated facades systems in small, midsize and large format.

·         Sandwich walls

·         Modules (e.g. Garages, transformer stations)

·         Storage units (tanks and silos)

·         Bridges (new construction and maintenance)

·         Free-form surfaces

·         Load-bearing shell structures

·         Balcony slabs

·         Maritime building elements

·         Load-bearing structure reinforcements

·         Concrete remediation, sprayed concrete applications.

Advantages of Textile Reinforced Concrete

1. Reinforced concrete has a high compressive strength compared to other building materials.
2. Due to the provided reinforcement, reinforced concrete can also withstand a good amount of tensile stress.
3. Fire and weather resistance of reinforced concrete is fair.
4. The reinforced concrete building system is more durable than any other building system.
5. Reinforced concrete, as a fluid material, in the beginning, can be economically molded into a nearly limitless range of shapes.
6. The maintenance cost of reinforced concrete is very low.
7. In structures like footings, dams, piers etc. reinforced concrete is the most economical construction material.
8. It acts like a rigid member with minimum deflection.
9. As reinforced concrete can be molded to any shape required, it is widely used in precast structural components. It yields rigid members with minimum apparent deflection.
10. Compared to the use of steel in structure, reinforced concrete requires less skilled labor for the erection of the structure.

Drawbacks of Textile Reinforced Concrete

1. The tensile strength of reinforced concrete is about one-tenth of its compressive strength.
2. The main steps of using reinforced concrete are mixing, casting, and curing. All of this affects the final strength.
3. The cost of the forms used for casting RC is relatively higher.
4. For multi-storied building the RCC column section for is larger than steel section as the compressive strength is lower in the case of RCC.
5. Shrinkage causes crack development and strength loss.

Future Prospects

A lot of ground research is happening to fully understand the potential of TRCs and what other kinds of materials can be used to further strengthen the material and increase its usage. Newer areas such as lightweight construction are also beginning to realize the potential of TRCs and the headwinds are towards faster adoption of the composite.

TRC has emerged as a novel composite with applications in non-structural, structural materials including thin and slender elements, repair and strengthening of existing structural members. But as of now, TRC has been applied to a limited extent only despite excellent intrinsic material properties and excellent material strength. Newer and innovative patents have to be introduced for a material which is a panacea to a host of problems in the building material industry and it needs to be marketed really well for adoption across city planners, architects, contractors, engineers and researchers. Many institutions and commercial companies are relying on semi-tested material combinations and are using despite ample space for improvement.

Moreover, standardization by world’s leading concrete labs and institutions needs to be done which would further fuel its adoption across a range of industries.

Conclusion

Fiber reinforcement has been used to reinforce concrete members for decades. It has combined well with concrete to help control cracking and increase toughness and other properties such as corrosion resistance. The use of traditional fiber reinforcement has led to the development of a new material called textile reinforcement (multifilament continuous fiber) which can also be used as the main reinforcement instead of steel reinforcement.

References

1.       Retrieved from: https://en.wikipedia.org/wiki/Textile-reinforced_concrete

2.       Retrieved from: https://en.wikipedia.org/wiki/Basalt_fiber

3.       Retrieved from: https://en.wikipedia.org/wiki/Carbon_fibers

4.       Retrieved from: https://grca.org.uk/pdf/congress-2015/02%20Actual%20applications%20and%20potential%20of%20textile-reinforced%20concrete.pdf

5.       Retrieved from: https://civiltoday.com/civil-engineering-materials/concrete/23-advantages-and-disadvantages-of-reinforced-concrete

6.       Retrieved from: https://theconstructor.org/concrete/fiber-reinforced-concrete/150/

7.       Retrieved from: https://civiltoday.com/civil-engineering-materials/concrete/23-advantages-and-disadvantages-of-reinforced-concrete