Бетонное волокно микрофиламенты монофиламенты скрученные волнистые из микрофибры полипропиленовое для

PP Fiber

Innovations in engineering design and construction, which often call for new building materials, have made polypropylene fiber-reinforced concrete applications. In the past several years, an increasing number of constructions have been taken place with concrete containing polypropylene fibres such as foundation piles, prestressed piles, piers, highways, industrial floors, bridge decks, facing panels, flotation units for walkways, heavyweight coatings for underwater pipe etc. This has also been used for controlling shrinkage & temperature cracking.

Properties of PP fiber

The raw material of polypropylene is derived from monomeric C3H6 which is purely hydrocarbon. Its made of polymerization, its high molecular weight and the way it is processed into fibers combine to give polypropylene fibers very useful properties as explained below:

♦ Chemical inertness makes the fibers resistant to most chemicals. Any chemical that will not attack the concrete constituents will have no effect on the fiber either. On contact with more aggressive chemicals, the concrete will always deteriorate first.

♦ The hydrophobic surface not being wet by cement paste helps to prevent chopped fibers from balling effect during mixing like other fibers.

♦ The water demand is nil for polypropylene fibers.

♦ The orientation leaves the film weak in the lateral direction which facilitates fibrillations. The cement matrix can therefore penetrate in the mesh structure between the individual fibrils and create a mechanical bond between matrix and fiber.

The fibers are manufactured either by the pulling wire procedure with circular cross section or by extruding the plastic film with rectangular cross-section. They appear either as fibrillated bundles, mono filament or microfilaments. The fibrillated polypropylene fibers are formed by expansion of a plastic film, which is separated into strips and then slit. The fiber bundles are cut into specified lengths and fibrillated. In monofilament fibers, the addition of buttons at the ends of the fiber increases the pull out load. Further, the maximum load and stress transfer could also be achieved by twisting fibers. 

Role of Fibers

Cracks play an important role as they change concrete structures into permeable elements and consequently with a high risk of corrosion. Cracks not only reduce the quality of concrete and make it aesthetically unacceptable but also make structures out of service. If these cracks do not exceed a certain width, they are neither harmful to a structure nor to its serviceability. Therefore, it is important to reduce the crack width and this can be achieved by adding polypropylene fibers to concrete.

Thus addition of fibers in cement concrete matrix bridges these cracks and restrains them from further opening. In order to achieve more deflection in the beam, additional forces and energies are required to pull out or fracture the fibers. This process, apart from preserving the integrity of concrete, improves the load-carrying capacity of structural member beyond cracking. This improvement creates a long post-peak descending portion in the load deflection curve. Reinforcing steel bars in concrete have the same beneficial effect because they act as long continuous fibers. Short discontinuous fibers have the advantage, however, of being uniformly mixed and dispersed throughout the concrete.

The major reasons for crack formation are Plastic shrinkage, Plastic settlement, Freeze thaw damage, Fire damage etc.

♦ Plastic shrinkage: It occurs when surface water evaporates before the bleed water reaches the surface. Polypropylene fibers reduce the plastic shrinkage crack area due to their flexibility and ability to conform to form. The addition of 0.1% by volume of fibers is found effective in reducing the extent of cracking by a factor of 5-10. The extent of crack reduction is proportional to the fiber content in the concrete.

♦ Plastic settlement: High rate of bleeding and settlement combined with restraint to settlement (e.g. by reinforcing bars) leads to settlement cracking. In case of PFRC, fibers are uniformly distributed. Fibers are flexible so they cause negligible restraint to settlement of aggregates.

♦ Freeze thaw damage: Small addition of polypropylene fibers in concrete reduces the flow of water through the concrete matrix by preventing the transmission of water through the normal modes of ingress, e.g. capillaries, pore structure, etc. The implications of these qualities in concrete with polypropylene fiber additions are that cement hydration will be improved, separation of aggregate will be reduced and the flow of water through concrete that causes deterioration from freeze/ thaw action and rebar corrosion will be reduced, creating an environment in which enhanced durability may take place.

♦ Fire damage: Heat penetrates the concrete resulting in desorption of moisture in outer layer. Moisture vapors flow back towards the cold interior and are reabsorbed into voids. Water and vapor accumulate in the interior thereby increasing the vapor pressure rapidly causing cracks and spalling in the concrete. In case of PFRC, the fibers melt at 160oC creating voids in the concrete. The vapor pressure is released in newly formed voids and explosive spalling is significantly reduced.

♦ Samples: We offer FREE samples within 200g for your laboratory test. Please feel free to contact us for samples. 

♦ Prompt delivery: Usually within 10 work days after order confirmed and payment received, according to order qty.

♦ Timely update: Loading Photos (on-site loading and finished-loading) and accordingly documents, service will send to customers timely.

♦ After-sale service: Feed back email after endusers received the cargo. We listen to the customer's comments and suggestions, for constantly developing and improving ourselves to provide better valued services. 

BOTAI

chemical building material Co.,Ltd

As a company that focus on technology and innovation, with more than 10 years of history, is committed to be the leader in the building additives industry.

Our products are widely used in a variety of aplications, such as Coatings, Drymix mortars, Pharma industry, Oil industry and so on.

To fulfill the requirements if rapid change on construction industry, BOTAI is continously investing in basic research to better understand how the fundamental mechanisms controlling the development of polymer.

Together with our unrivalled product portfolio, srong R&D capability and techncial support, we are able to supply all of our partenrs not only high-performance, more sustainable and more cost-effective construction chemicals, but also, formulation expertise and professional silutions to ensure their continued success in a very demanding and ever-changing industry.

Henan BOTAI Chemical Building Materials Co., Ltd.

Contact: Andrew Gao

Adress: NO.18, East of Dongfeng Road, ZhengzhouCity, Henan, China

Tel: +86-371-55988201    

Mob: +86-15639327366 / +86-15137135861 (Whatsapp)

Web: www.botaichem.net