RECOMMENDATIONS FOR USE OF STEEL FIBRE

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Steel fibre with curved ends

RECOMMENDATIONS
FOR USE OF FIBRE ISSUED BY «Dnepro Metis Work LLC»
TO PREPARE THE STEEL FIBRE CONCRETE MIX

«Dnepro Metis Work LLC» produces steel fiber manufactured from a cold drawn wire for general purpose, nontreated thermally, without coating according to GOST 3282-74 with high tensile resistance - 1450 N/mm2. The selected form of fiber ensures its uniform distribution in the concrete and provides the lowest tendency to form "hedgehogs" comparing to a fiber of another types. For a short time fiber can be uniformly distributed in the concrete, forming a uniform three-dimensional lattice with a full clutch of each fiber with concrete. Thus, a fiber reinforced concrete is an anisotropic material with mechanical characteristics exceeding the traditional technology reinforced concrete characteristics.

 

Content of fibre in the steel fibre concrete (fibre consumption per 1m3 of the steel fibre concrete mix) is determined by the requirements to its physical and mechanical properties required by the conditions of practical application.

 

Depending on the application of the steel fibre concrete, the content of fibre can be recommended as follows, kg/m3:

- industrial floor slabs: 20-40;

- residential houses constructions: 25-50;

- structures and facilities exposed to the environment: 40-70;

- structures of tunnels, roads, etc.: 50-200;

-       protective structures, marine structures and other special cases – 100-200.

Preparation of fiber-reinforced concrete

For  fiber-reinforced concrete mixture preparing such following materials: cement, fillers, chemical additives, water, and steel fiber are used. Nano additives using for producing fiber-reinforced concrete with improved physical and mechanical characteristics determined by project should be chosen in accordance with the recommendations and manufacturer specifications and should be used after thorough laboratory studies and test practical application.

The main quality characteristics of fiber-reinforced concrete mixture are:

- the homogeneity of the mixture (including uniform distribution of the fibers in concrete);

-concrete workability;

-concrete can be handled without segregation.

Steel fibre concrete mix is prepared, as a rule, in mass-produced positive action concrete-mixing machines. It is allowed to also use truck mixer for preparing steel fibre concrete mix. For uniform distribution of the fibers by concrete mixture without the formation of clots and "hedgehogs" the introduction of the mixture components must be realized strictly by the following sequence: first the fibers are mixed with gravel, then injected sand, cement and water with additives. It is recommended to add fiber to the mortar mixer with a certain time lag (at least 10 to 15 seconds) from the start of the gravel supply. The velocity of the feeding of fibre to the mixer by scattered uniform flow should be about 1.5 to 2 kg per sec by feeding manually and not more than 3 kg per sec in case of using a vibrating chute with a grid. Any way it is necessary to control the presence of the "hedgehogs" in the mixture and, if they occur, fiber feed rate should be reduced. The optimum feed rate is selected at the trial batches. To do this, at the end stage of mixing the fibers with gravel the mixer is stopped and checked by the presence of a mixture of "hedgehogs", then accordingly correct the feed rate of fiber. Chosen speed should be observed in the preparation of steel fibre concrete mix in the future operation. Subsequent  feeding of components like sand, cement and water including the additives must be carried out only after the introduction of the fibers and after its mixing with gravel during from 10 to 15 seconds.

ADVANTAGES OF USING FIBRE
PRODUCED BY «Dnepro Metis Work LLC»

• considerably higher resistance to cracks and bending (to 35%);
• excellent cohesion with concrete (to 25%);
• higher impact strength (to 35%);
• higher water permeability of concrete (to 50%);
• reducing the formation of internal stresses due to plastic shrinkage (to 50%);
• strengthening of corners and edges (to 90%);
• increasing of frost-resistance (to 35%);
• increasing of the wear resistance of the concrete surface (to 70%);
• increasing of the impact and fatigue strength of concrete (more than  200%);
• reducing the initial and definitive solidification; special equipment is not needed;
• if destruction of concrete under load is observed there is no separation of fragments, fragments remain bounded to each other;
• no lumps are formed;
• simple of usage;
• simple finishing of surfaces;
• extended service life of constructions.

ECONOMIC BENEFITS OF STEEL FIBRE USE

• reduction of labour (to 20%);
• reduction of construction period (to 30%);
• reduction of slab thickness;
• easy manual or machine-made placement.

APPLICATION OF STEEL FIBRE PRODUCED BY                            «Dnepro Metis Work LLC»

• industrial flooring (floors of workshops and storage areas, cinema halls);
• jointless flooring; other poured floors;
• reinforcement of road base;
• pipelines;
• subways, railroad and road tunnels;
• production of concrete constructions;
• water tunnels;
• oil and gas tanks;
• facades, walling constructions;
• stabilization of slopes, inclined walls;
• bank vaults, safes
• basements made of prefabricated blocks, water wells, garages;
• runways;
• service hangars;
• port pavements, container terminals.