About GRC

GRC is a kind of artificial stone, manufactured by disperse reinforcement of cement concrete on dense aggregates (sand), alkali resistant glass fiber.

The composition of GFRC is sand, portland cement and water used for the production of normal concrete and alkali-resistant glass fibers in the form of pieces of glass-fiber fibers uniformly distributed throughout the volume of a fine-grained concrete matrix.

It is generally known that a lack of any concrete stone material is a low tensile strength.

The GRC perceive the tensile stress on the glass fibers, which are three times the modulus of elasticity of concrete module, which significantly increases the resistance of the composite tension and bending.

As a result, there is such a high strength, resilient material such as plastic and GRC (Fig.15.) Consisting of the fine-grained concrete (matrix) reinforced with glass-fibers lengths of fibers that are uniformly dispersed throughout the volume of the concrete matrix.

GFRC combines high intrinsic conventional concrete compressive strength dramatically with increasing strength due steklofibroarmirovaniyu bending and stretching (4-5 times), impact strength (10-15 times) frost resistance (300 cycles). It is waterproof (W6-W20, GOST 12730), has a high degree of adhesion to the conventional concrete and has a high resistance to cracking.

This eco-friendly and safe material that does not contain harmful ingredients and belongs to the category of non-combustible materials. It is highly resistant to chemical attack, is not subject to corrosion and rot, has an increased resistance to the penetration of chlorides.

Fiber content of GFRC in the process according to the method is typically 3 - 5% by weight of the mixture.

When applying plasters fiberglass-reinforced degree does not exceed 1-2%, which can effectively inhibit cracking and provide a high resistance to cracking and peeling.

In addition to the exceptional functional properties of GRC distinguish increased architectural expression, as well as an extraordinary plasticity. The absence in the body of articles hard reinforcement cage provides an unlimited range of shaping. GRC is able to acquire the complex spatial form and recreate the most unexpected for the outlines of the stone material.

GFRC exactly copies the finest details of the matrix surface, produces a wide variety of colors and finishing the front surface, is able to simulate the appearance, texture and color of a variety of finishing natural and synthetic materials.

Thus GRC products have a small cross-section (ranging from 6 to 20 mm), and are considerably lighter in comparison with the products of conventional concrete.

It is these properties of glass-fiber in combination with high strength and performance characteristics provided him with wide application in precast-monolithic housing and other types of construction all over the world.

GRC production technology.

Upon receiving the concrete, reinforcing glass fibers, it is important not only to the correct selection and rational combination of raw materials, and technology of its manufacture.

The properties of the final composite are highly dependent on ensuring uniform distribution of fibers in concrete, their orientation, anchoring, determining to a large extent of the material's ability to resist external influences. Most of the products and structures made of glass-fiber, as a rule, one of the two main technological schemes - pnevmonabryzg vibromolding mix and premix (or premixing), that is, pre-mixing chopped glass fibers with cement-sand mortar.

Pneumatic spraying

In the first case we are talking about spraying cement-sand mortar under pressure (like shotcrete) with simultaneous supply of fiber at a high speed.

Procedure:

1. Preparation of a mixture of cement, sand, water and chemical additives produced in high-speed wide-mixer with high shearing.
2. The mixture is then discharged into the discharge grout injection pump station, from where it flows into a special spraying gun.
3. The chopping gun unit is also supplied fiberglass filament (glass fiber rovings), where it is chopped into short lengths (fiber) and then mixed in an air stream with a cement-sand mixture.
4. Then this mixture is sprayed GRC is applied to the form or on a forming relief.

Vibromolding

The method involves forming a premix prior administration already chopped glassfibre in the cement paste, followed by vibromolding.

The resulting material is a process commonly referred to as GRC premix. Its preparation involves two steps:

1. First, in a high speed mixer preparing the mixture of cement, sand, water and chemical additives.
2. Then the mixture is already at a low speed of mixer working, glassfibre added.
3. Next premix filled in form and vibro-stabilization is produced.

Newly-formed products obtained by both processes, must be stored for 7 days in a humid environment. Durability of GFRC pneumatic spraying is usually higher than GFRC premix.

1. Primarily, this is due to the fact that when the fiber content in pneumatic spraying may reach 5-6%, while in this figure is limited premix 3-3.5%.
2. Secondly, at the GRC, resulting pnevmonabryzga, water-cement ratio lower than that of the premix.
3. Third, pneumatic spraying provides more long stretches of glass and give them a planar (as opposed to the three-dimensional in the premix) orientation.

The choice of the production method is determined by such factors as specified requirements in respect of strength, size, shape, architectural design conditions.

Generally, large size articles such as wall panels, sprayed, while small articles formed from the premix.

Types of materials used for making molds in the manufacture of products from SWFs.

Quality shaping equipment is a very important detail in the issuance of GRC products.
In the form of requirements for the castings are very simple and are as follows:

• Forms must be strong enough to withstand the pressure of the mixture without deformation when the pouring.
• Materials for making molds can be fiberglass, plywood, silicone or other material which does not react with the concrete and can provide a sufficiently smooth front surface texture.
• Molds for casting during storage must be operated correctly. This is necessary to meet the in-process specified in the technical specifications for manufacturing casting tolerances, i.e. angled, linear dimensions and dimensional details.

Types of forms:

plywood forms (up to ten castings made from one form of product);

fiberglass form (thirty castings made from one form of product)

silicone form (from twenty to fifty casting products from one form depending on the quality of silicone)

express form (manufactured products from one single casting mold) - disposable form made of expanded polystyrene.

The most expensive are considered fiberglass and silicone molds for their production the product itself should be produced first. To this end, the sculptors of the company, use templates made of gypsum layout on which the forms are made form.

After making the profile form, it is used for start-up in production

In the manufacture of products used curved shape of the glass fiber in the manufacture of rectangular products (used form of plywood, architectural elements with drawings eg. keystone) are made of silicone mold.

The most financially advantageous for today are the form of plywood, they do not require the presence of manufacturing the product.

To reduce the cost of production of this type of form, the manufacturers of such products as much as possible try to get away from the highly paid and not very productive manual labor, actively using in the production of computer-controlled machines. Automation of production processes allows not only to increase output and reduce costs, but also to achieve a very high precision workpieces sizes.

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