Polymer composite reinforcement for reinforcing concrete structures appeared in the development of new materials for construction works back in the sixties of the last century. Scientists tried to bypass the sharp corners and correct shortcomings of metal as the basis of structures, so they were looking for a better substitute. Particular attention was paid to mechanical, physical and other properties. Scientists were also interested in the chemical resistance to water, alkalis and other aggressive substances. As a result the composite armature was developed.
Why metal armature needs to be replaced
The reinforcement of concrete with steel rods has been going on for a long time, but now they are coming on the heels of new materials that have begun to displace steel from concrete structures. Steel reinforcement has great advantages: high strength, relatively low cost, plasticity. In addition to positive aspects, there are many negative ones: low resistance to various types of corrosion, weighting of the structure due to the high density of the material, electrical conductivity and interference with radio waves. These disadvantages do not have reinforcing mesh or bars made of composite at all. This helped them to displace steel from various spheres of construction: pouring foundations, creating floor slabs, etc. This building material has been used abroad for quite a long time. It is especially popular in areas of high seismic activity.
Types of material for making reinforcing meshes
Depending on the main component of the mesh and rods, the following types of composites can be distinguished: basalt-plastic and fiberglass. In addition, there are also less common: glass reinforced and polyethylene terephthalate. Each type has its own advantages and disadvantages. Let’s dwell in more detail on the main types.
Basalt plastic reinforcement
This composite material is created on the basis of fibers of the natural mineral basalt and bonding composition of resins. The result is very interesting properties. The rods have a characteristic corrugation along the length.
The obvious advantages include:
- High degree of resistance to high temperatures and resistance to combustion, low thermal conductivity;
- Has good mechanical characteristics on breaking and stretching, it is possible to bend without violation of integrity. If to compare with the steel analogue the characteristic of the composite on the threshold of durability exceeds steel in 3 times;
- Resistance to different types of corrosion is at the level of stainless steel. Basalt plastic withstands not only high humidity but also influence of aggressive substances like chlorine salts, hydrochloric and sulfuric acids, nitrogen oxides;
- Long service life without changing characteristics. Service life is not less than the foundation or slab, so the overhaul can be carried out much later than in the case of steel bar;
- Low density of the composite (5 times less than steel) reduces the load of the building on the foundation and the ground;
- Is a dielectric and absolutely safe in case of possible breakdowns of electric networks;
- Basalt plastic does not interfere with electromagnetic waves, so it is widely used for the construction of foundations, walls and ceilings of medical facilities, airports, radar facilities, research institutes, where a large number of sensitive to interference and radiation equipment.
All these properties allow the basalt-plastic mesh for reinforcement of foundations and other elements to successfully replace steel in the construction of port facilities, highways, fences with heat protection function, engineering networks and supports for electric lines.
The obvious and main disadvantage of this quality substitute for steel for foundation reinforcement mesh is the high cost so far.
Made from glass fiber and thermosetting resin. The second component is needed to knit together and create a structure of certain properties. The material for mesh and bars for reinforcement of concrete foundations is applied transverse spiral corrugation.
The distinct advantages of fiberglass include:
- Among the obvious and main advantages in the first place is the low weight at a significant strength. Fiberglass is used for pouring foundations and other structures with unstressed reinforcement;
- Good resistance to moisture. When exposed to salts, acids or other chemically aggressive substances, properties change, but only slightly;
- Does not impede the passage of electromagnetic waves and radiation, does not create shielding and interference;
- Fiberglass mesh or rods have high elasticity and can withstand heavy loads. Have a small elongation coefficient;
- Well withstand low temperatures. Thermal expansion is almost the same as that of foundation or wall concrete, so there are no cracks or rips in the building structure;
- The density of the material is 4 times lower than steel. At the same time, it is just as easy to assemble and knit a reinforcing mesh. The difference lies in the use of cable ties;
- The material is easy to process. It can be sawn off with an ordinary hand hacksaw. Mesh of small diameter can be cut simply with wire cutters.
The obvious problems in the characteristic can be attributed to the low resistance to fire. Fiberglass can be used at temperatures up to 200 degrees Celsius. Therefore, this building material is not used in structures where high temperatures are possible.
Application of composite reinforcement
Composites are increasingly used in the construction of industrial and civil facilities. Mesh and rods from composite are more and more often used for pouring the foundations and private houses. Especially the material for erection of constructions in winter time took a fancy to the material. Here are some areas of use:
- For casting non-tensioned and tensioned elements of buildings that work periodically or continuously at temperatures between -700 and +1000 C and various aggressive environments;
- For construction of walls from small building elements (brick, stone) in winter time. In case of frosts builders put special additives into cement mortar that destroys steel;
- In the construction of power line supports and other places where insulation is needed;
- In corrosion-resistant structures and structures, such as sewers, utility tunnels, electrolysis baths, and so on;
- For building restoration;
- For the manufacture of small architectural forms;
- For the construction of port facilities, slopes, retaining ponds;
- In the manufacture of curbs, paving tiles, repair of roads, bridges;
- For thin walls, partitions and sound insulation panels.