Fiber foam concrete: more expensive - yes, but is it better?
Increased requirements for the thermal performance of external walls and roofs of residential buildings, caused by the requirements for energy efficiency of buildings under construction and reconstruction, predetermined the appearance on the market of a wide range of thermal insulation materials.
Fiber foam concrete is one of the lightweight concretes.
The scope of thermal insulation is very diverse. Plate heaters are used for effective brickwork, as well as for roofing, brick walls are sheathed with them, after which ventilated facades are made. Large blocks of lightweight concrete are used for the construction of self-supporting walls with floor-by-floor cutting in multi-storey residential buildings and for laying external walls in the construction of low-rise housing estates. In the market niche of lightweight concrete blocks, there are now a lot of very different offers, and here they offer both well-known aerated concrete and polystyrene concrete blocks, as well as relatively new ones - foam concrete, as well as the latest developments - fiber foam concrete blocks.
Comparison of some physical and mechanical characteristics of lightweight concrete.
Fiber foam concrete - foam concrete reinforced with randomly arranged pieces of synthetic or natural fiber (fibers) about 50 mm long. It is said about fiber foam concrete and blocks from it that this material is both structural and heat-insulating and has high strength. To verify the validity of these statements, one should look at the physical and mechanical characteristics of this type of lightweight concrete and compare with other types of similar materials.
The correctness of this comparison, of course, leaves much to be desired, since the characteristics of lightweight concretes are very dependent on their composition, and the compositions may vary depending on the preparation technology and the chemical composition of certain ingredients. However, by analyzing the data in this table, certain conclusions can be drawn. Thus, fiber foam concrete has a minimum thermal conductivity among all the materials under consideration, as well as foam concrete, which allows us to speak of high thermal insulation properties of this material. The compressive strength of fiber foam concrete is slightly higher than the original foam concrete and is quite comparable with this parameter of other lightweight concretes. From the above data, we can conclude that the characteristics of all non-autoclaved lightweight concretes are approximately identical, so it is difficult to talk about noticeable advantages of one of them. Price indicators also largely depend on the technology of preparation, composition and other variable values.
What gives dispersed reinforcement?
However, back to fiber foam concrete. Of course, the addition of fibers to foam concrete will not be able to change either the density or thermal conductivity of this material, this can only affect the strength and performance characteristics. One of the main disadvantages of foam concrete is its high brittleness, which leads to cracks and chips in the blocks when working with them. In addition, non-autoclaved foam concretes are characterized by high shrinkage deformations, which leads to products with cracks or even their destruction. The introduction of non-metallic mineral or polymer fibers into the composition of cellular concrete makes it possible to eliminate or at least minimize these negative qualities. But whether dispersed reinforcement increases the strength of cellular concrete, and if it does, how much is a moot point. So, from the materials in which a link is given to the research of the RSSU (Rostov-on-Don) (http://www.btc-mos.ru/index.php?id_article=165) it follows that when polymer fiber is included in the foam concrete in the amount of 1 kg per 1 sq.m, its compressive strength does not increase. Moreover, an increase in the amount of fiber up to 3 kg per 1 sq.m generally reduces strength by 10%. At the same time, research data from SPbGASU (LISI) (http://fibron.ru/articles.html?id=6) say that the introduction of synthetic fibers into the composition of foam concrete makes it possible to increase the compressive strength up to 1.5 times. Both studies confirm that fiber reinforcement significantly increases flexural strength: SPbGASU speaks of 200 - 250%, and RSSU about an increase in strength by 95% with a fiber content of 1 kg per 1 m 2 and an increase in this indicator by 60% for every 1 kg increase in the amount of fiber. In addition to the strength characteristics, studies at SPbGASU record an increase in the impact resistance of fiber foam concrete by a factor of 7–9, as well as a sharp (up to 75–100 cycles) increase in frost resistance due to the ordering of the pore structure in the material. The almost complete disappearance of shrinkage cracks is also recorded, both at the manufacturing stage and during operation. At the same time, fiber foam concrete retains all the real positive properties of foam concrete: high thermal performance; soundproofing ability; resistance to decay, mold, fungi and rodents; ecological cleanliness; incombustibility; the ability to perceive temperatures up to +400 0 C. But for some reason, nowhere is it said that all the positive indicators of fiber foam concrete are extremely dependent on the concrete mix production technology. After all, if a relatively uniform distribution of fibers over the volume of the batch is not ensured, then a simple foam concrete will be obtained that does not have increased strength. In this, fiber foam concrete is similar to polystyrene concrete, for which it is also very important that the foamed polystyrene granules do not accumulate at one point, but are placed throughout the volume.
Where to use fiber foam concrete?
Now about the use of concrete fiber concrete. Its qualities, peculiar to this particular material, give the maximum effect when used as:
thermal insulation of pipelines for process fluids and hot water, where its low weight, increased strength and absence of cracks will allow it to compete with traditional materials;
fire protection of steel and reinforced concrete structures, allowing to achieve the required fire resistance of load-bearing columns and beams;
special anti-ricochet finishing of buildings and structures for military purposes.
The use of fiber foam concrete for monolithic or block walls in low-rise manor-type houses, self-supporting walls of floor-by-floor cutting for multi-storey construction is possible, but should be used with the economic efficiency of using such material. The same can be said about the use of fiber foam concrete for the manufacture of heat-insulating slabs, tongue-and-groove partition slabs, etc. In these cases, the parameters of fiber foam concrete do not give it any tangible advantages over other types of lightweight concrete. As regards the production of floor slabs and lintels from fiber foam concrete, it is doubtful that for certain spans they will not require traditional reinforcement.
Building a house today is easy and simple. Technology allows you to do this quite quickly and at an affordable price. The most popular building materials for the construction of individual houses today are foam concrete blocks, aerated concrete blocks and fiber foam concrete.
House of aerated concrete blocks - it's fast!
Building houses from aerated concrete began back in the 1980s of the last century, and today this material has long surpassed classic brick in terms of its consumer qualities. Compare for yourself - the main advantages of aerated concrete are low thermal conductivity, high thermal stability, noise insulation and frost resistance. Aerated concrete blocks are light, which means that it is not required to build a powerful foundation. And the price of a gas-block house is quite affordable for almost everyone.
Gas block with cladding and insulation - 6955 rub/m2 of finished wall (work with materials)
Fiber foam concrete - durable!
Houses made of fiber foam concrete are built, practically, for centuries. Fiber foam concrete does not have the disadvantages of aerated concrete, since this material is made from foam concrete reinforced with synthetic or natural fibers. Buildings made of fiber foam concrete are capable of retaining heat 20-30% stronger than other building materials. Fiber foam concrete is able to control the microclimate in the room: in summer it is cool in such a house, and in winter it is warm and dry. In terms of its environmentally friendly properties, fiber foam concrete is second only to wood. At the same time, it has no equal in terms of durability.
The composition of fiber foam concrete includes high-quality cement, selected sand, fiber (reinforcing polypropylene threads) and an air-entraining additive (foaming agent) to create a porous structure.
A wall thickness of 30 cm of fiber-reinforced concrete can provide heat savings comparable to brickwork two meters wide. At the same time, fiber foam concrete is the only building material that, with a minimum masonry width without insulation, meets the requirements of modern SNIPs for heat saving. And the sound absorption quality of fiber foam concrete is proved by such an example - with an inner wall 20 cm thick, sounds from the next room are completely inaudible.
A monolithic house made of fiber foam concrete is perfect in everything! This is the best value for money!
Fiber foam concrete - 5900 rubles / m2 of the finished wall (work + materials)
The know-how of today is the monolithic construction of fiber foam concrete. The advantages of this method of building a house are obvious.
Firstly , you save on the absence of the process of laying blocks. Fiber foam concrete according to the technology of monolithic housing construction is poured directly into the annular masonry, removable or fixed formwork.
Secondly , the integrity of the frame of the house is ensured - there are no joints that allow drafts to pass through, nor the use of a solution that creates voids in the walls, there are no “cold bridges”.
Thirdly , the walls of the house with a monolithic filling of fiber foam concrete are smooth and even, which means that they do not require additional plastering work.
Fourth , houses made of fiber foam concrete are fireproof. The Ministry of Emergency Situations recommends the use of fiber foam concrete walls at facilities where there is a risk of fire. Fiber foam concrete has the first degree of fire resistance, does not emit harmful and toxic substances during open fire and retains the strength of the structure.
Fifth , a monolithic house made of fiber foam concrete - light and stable. It can be erected on almost any site, providing all the required quality characteristics. The price of a monolithic house made of fiber foam concrete with a front brick facade is much cheaper than a similar house made of gas blocks with insulation and brick cladding. And the quality and durability of fiber foam concrete is many times higher than the characteristics of any other building material.
These are the main advantages of using fiber foam concrete. In addition, it can be noted that when building a monolithic house from fiber foam concrete, you do not need to spend money on transportation costs for the delivery of blocks to the construction site - fiber foam concrete is produced directly at the construction site.
Our company produces fiber foam concrete in full compliance with the approved technological process on high-tech equipment. All components of the solution are imported, of the highest quality. Fiber foam concrete is foamed with special blades at a certain speed. In its production, a specially developed foaming agent is used, which ensures the highest quality of fiber foam concrete.
We build houses from fiber foam concrete - high quality, quickly, easily and at the most affordable price!
Blocks based on foam concrete with the inclusion of fiber have become very popular with modern builders. This is due to the fact that this material has a number of positive qualities that are so necessary for the walls of the house. However, it is worth remembering that fiber foam concrete is a product made of sand, cement and fiber-based foam, which means that it also has its drawbacks associated with the production technology and the components used.
Properties and scope
To begin with, it must be said that materials of this type are manufactured by certain companies. Therefore, it is worth talking about product quality based on general characteristics, and not based on a specific batch. Given this, we will consider fiber foam concrete as a separate product created without violating the technical process ().
Characteristics
First of all, it is worth saying that this type of material can be safely called the most environmentally friendly. It is assigned index 2, while wood is in first place, and brick is in tenth ().
At the same time, fiber foam concrete does not need additional processing, which would reduce this indicator, which cannot be said about wood, which needs impregnation and fire protection.
- Special attention should be paid to the fact that products made from this material can have different dimensions. Large blocks are especially in demand, as they significantly reduce installation time and simplify it. Also, when making them, you can take into account some features in advance and create additional forms, which will completely eliminate the diamond drilling of holes in concrete or reduce their number to a minimum.
- It must be said that this material retains heat well, but it should not be used without additional insulation. The fact is that fiber foam concrete blocks do not have a homogeneous structure, since air bubbles in them are arranged randomly and have different sizes. It is because of this that it is worth installing at least a thin insulation so that the insulation is uniform, although this may not be done in regions with a warm climate.
- Properly made foam fiber concrete has excellent antibacterial performance.. He is not afraid of mold or fungus, but professional craftsmen still advise adding a primer with similar additives to the solution or performing subsequent processing.
- Usually, the disadvantages of fiber foam concrete are not as pronounced as the advantages. They are relatively low strength. Moreover, this material is quite suitable even for the manufacture of three-story houses.
- It is also worth mentioning that these blocks are very easy to process.. By choosing them to create walls, you can avoid such a process as cutting reinforced concrete with diamond wheels.
Advice! When purchasing a batch of such material, you should ask the seller or manufacturer for a quality certificate. It must describe all the declared characteristics and their compliance.
Application area
Given that such blocks are lightweight, they are often used to make interior partitions or lintels.
- Many craftsmen use this material to create small buildings and houses. The fact is that its price and properties make it possible to save money and solve a number of problems associated with insulation and environmental cleanliness.
- It is not recommended to use such blocks for the manufacture of a foundation or a plinth. Usually the installation instructions suggest using stronger products in such cases.
Advice! Do not confuse this type of material with aerated concrete, since they have completely different characteristics, which naturally determines their scope.
- When doing work with your own hands, it is worth remembering that these blocks have a certain absorbency, and therefore the solution is made slightly liquid.
- It is worth remembering that each manufacturer of these materials has its own system of standards, which does not always coincide with popular dimensions. Therefore, when ordering blocks, you need to know in advance about their size.
- Do not leave finished products made of such material without an appropriate finish. It will not only decorate the appearance, but also serve as additional protection.
Output
After reviewing the video in this article, you can learn more about this type of building material. Also, based on the text above, it is worth concluding that for small buildings, such blocks are the most optimal and can be completely used without insulation ().
However, it must be remembered that fiber foam concrete does not have a very good appearance and needs additional finishing. At the same time, its technical characteristics allow you to save a lot of money, which is quite justified.
The production enterprise LLC "BAZA SM" produces products from non-autoclaved fiber foam concrete in accordance with TU 5741-001-80392712-2013 (Certificate of Conformity No. ROSS RU.AG75.N05997 dated 11.10.2013).
With a low specific gravity (on average, 3 times less than a brick), fiber foam concrete has strength sufficient for the construction of cottages with load-bearing walls up to 3 floors.
It has good heat and sound insulation properties. 200 mm of fiber foam concrete with a density of 600 kg/m 3 is equivalent in terms of heat and sound insulation to approximately 1000 mm of brickwork. In houses built of fiber foam concrete, it is not cold in winter and not hot in summer.
Fiber foam concrete is a fire-resistant material, as evidenced by a fire certificate and tests for fire resistance of wall structures (Fire certificate for products made of fiber foam concrete No. NSOPB.RU.PR014.N.00091 dated 19.03.2014).
Fiber foam concrete is easily sawn with a hacksaw. In construction stores, a foam concrete hacksaw with victorious soldering is offered.
- Due to the introduction of fibers into the composition of foam concrete, a more closed pore structure is formed, heat-insulating, sound-proofing and other characteristics are improved:
- fiber foam concrete is less sensitive to moisture,
- in terms of frost resistance, fiber foam concrete is several times superior to most of the existing wall materials, the durability of the material increases,
- impact strength increases, brittleness decreases, it becomes possible to transport the material over any distance by any means of transport,
- increases the tensile strength of the material in bending, which makes it possible to manufacture products of complex configuration,
- the specific resistance to pulling out screws is significantly increased.
| Physical and mechanical properties of fiber foam concrete | ||||||
|---|---|---|---|---|---|---|
Type of fiber foam concrete |
Density, kg / m 3 |
Class by |
Frost resistance grade, cycles |
Vapor permeability, mg/(m h Pa) |
Thermal conductivity, |
|
dry |
for operating conditions "A" |
|||||
heat insulating |
||||||
B1; B0.75; B0.5 |
||||||
Structural and heat-insulating |
B1.5; B1 ;B0.75 |
|||||
B5; B3.5; B2.5; B2 |
||||||
Table of energy efficiency of fiber foam concrete and aerated concrete
Name of indicator |
Aerated concrete D500 |
Fiber foam concreteD500 |
Note |
|
GOST 31359-2007 |
TU 5741-001-80392712-2013 |
|||
| The coefficient of thermal conductivity of the material in a dry state, W / m ° C | The index of fiber foam concrete is better by 30% |
|||
| Coefficient of thermal conductivity of the material under conditions "A"*, W/m °C | ||||
| Thermal conductivity coefficient at equilibrium weight humidity W = 4%**, W/(m °С) |
Note:
* - Operating conditions are determined in accordance with the requirements of SP 131.13330.2012 "Construction climatology". Operating conditions "A" correspond to the climatic conditions of Rostov-on-Don, Krasnodar, Astrakhan, Volgograd, Voronezh, Belgorod, etc.
** - data according to table A.1 of GOST 31359-2007 "AUTOCLAVE CELLULAR CONCRETE"
Comparative characteristics of fiber foam concrete
Comparison of wall structures with equivalent heat transfer resistanceof the most common fireproof wall materials.
| Indicators | Ceramic brick wall (voidness-13%, density 1600 kg / m 3 | Wall made of ceramic solid bricks (density 1800 kg / m 3) with insulation | Fixed formwork made of expanded polystyrene and reinforced concrete with a density of 2500 kg / m 3 | Wall made of aerated concrete blocks with a density D500 kg/m 3 |
Wall made of fiber foam-concrete blocks of BAZA SM LLC with a density of D500 kg / m 3 |
| Wall thickness, m | 1,29 | 0,46 | 0,25 | 0,40 | 0,30 |
| The coefficient of thermal conductivity of wall materials in conditions "A", W / m ° C | 0,58* | 0,041 / 0,7* | 0,041 / 1,92* | 0,141** | 0,111*** |
| Frost resistance of the outer wall material, cycles | 35 | 35 | -- | 35 | 75 |
| Weight 1m 2 walls, kg | 2370 | 800 | 375 | 270 | 200 |
| The cost of 1 m 2 of the wall, taking into account materials and work on the construction of the wall, rub. | 5990**** | 1970**** | 2025 | 1850 | 1600 |
* - data according to SP 23-101-2004 "Design of thermal protection of buildings"
** - data according to GOST 31359-2007 "AUTOCLAVE CELLULAR CONCRETE"
*** - data according to TU 5741-001-80392712-2013 "NON-AUTOCLAVED FIBERFOAM CONCRETE PRODUCTS"
**** - the cost of 1 m 2 of a ceramic brick wall is calculated based on the condition of using only backing bricks
Fiber foam concrete is the same foam concrete, only in which reinforcing additives are added during the mixing process - fiberglass. In the process of kneading, the fibers intertwine with each other and create a very durable and flexible material.
For successful installation of structures, a tensile strength level of at least 1 MPa should be ensured. For autoclaved cellular materials, this ratio is reduced to 6...8%. That is, even if the structure is made of autoclaved concrete with a density of 1000 kg / m 3, with a strength class of B10, the Rbt value does not reach the required level.
A technological way out of this situation is the dispersed reinforcement of foam concrete with fibers, which can increase their tensile strength by 5...10 times. Increasing the tensile strength of a material entails a significant list of advantages, the manifestation of which is important in the manufacture of products, their transportation, installation and operation of constructed facilities. Dispersion-reinforced non-autoclaved foam concrete is called fiber foam concrete (FPB). The most important physical and mechanical properties of fiber foam concrete of various densities in comparison with traditionally produced cellular concrete are shown in the table.
From the data given in the table, it follows that the increased tensile strength significantly increases the weather resistance of fiber foam concrete compared to foam and aerated concrete. The presence of dispersed reinforcement in the structure of interpore partitions drastically affects the magnitude of vapor permeability and quite significantly on thermal conductivity. And if we take into account the fact that the thermal conductivity of water is 20 times higher than the thermal conductivity of air, then the global thermal effect becomes clear, which can be achieved with the correct manufacture and use of fiber foam concrete.
Fiber foam concrete differs from existing types of cellular concrete:
Increased tensile strength and fracture toughness;
Reduced thermal conductivity and shrinkage deformability.
The implementation of this principle, due to the properties of the material, eliminates the formation of punctures and cracks from the impact of random shock loads, and makes it possible to refuse to plaster the surface of walls made of such products, because the degree of roughness does not exceed 2 mm. That is, to obtain a smooth surface of the wall, puttying is quite enough.
Comparison of the thermal conductivity indices of equal-density gas, foam and FPB (Table) shows that the latter favorably (by 15...20%) differ for the better, while the vapor permeability of FPB is less. According to our data, the vapor permeability of FPB with a density of 700 kg / m 3 corresponds to brickwork on a cement-sand mortar, the density of which is at least 1800 kg / m 3.
Jumpers:
Loads on window blocks are compensated by jumpers. Reinforced concrete lintels are “cold bridges” that worsen the thermal properties of enclosing structures, therefore, more than one lintel is often installed over the window opening along the thickness of the wall, but several thin ones, between which mineral wool heat-insulating materials are laid, therefore, at the time of putting the object into operation, everything is “fine” ". But to the question of how to replace the heat-insulating layers after their caking, the builders have not yet given an answer. If reinforced concrete lintels are replaced with heat-efficient bar or arch type made of fiber-reinforced foam concrete, then the need for additional thermal insulation of this element of wall structures can be eliminated.
Fibo foam concrete test:
During 2010, an initiative group of specialists (Nabokova Ya.S., Chumakin E.R.) manufactured and tested under the action of a long-term load a floor slab measuring 900x300x4800 mm from fiber foam concrete with a density of 800 kg / m 3, reinforced with bulk metal frames. Tests have shown that the achievement of the allowable deflection (according to the standard 6.85 mm) took place after exceeding the load of 730 kg / m 2, i.e. 2.4 times higher than the standard for slabs intended for housing.
At a specific load of 2.2 t/m 2 (4 times higher than the standard), the deflection of the slab in the middle part of the span reached 35 mm, but no visible cracks were found in the stretched zone of the product. The slab did not receive local collapse and in the places of support. With further loading of the slab up to 8.9 tons, the deflection kinetics were not recorded. The gross weight of the tested slab was 1.2 tons, which is at least 15% lighter than a hollow core reinforced concrete slab of the same area. Of course, one-time tests do not allow making global generalizations. However, this initiative experiment shows the fundamental possibility of manufacturing large-sized products from cellular concrete reinforced with fibers, designed not only to improve the thermal and acoustic properties of buildings, but, possibly, to absorb loads.
In addition, the universal shaping properties of fiber foam concrete mixtures make it possible to diversify the architectural appearance of interiors and facades.
Identification of the shortcomings of other heat insulators:
In comparison with fiber foam concrete, it is known that PPS has low heat and fire resistance. Before ignition at t = +80 °C, destruction develops in the EPS, leading to a change in volume and the release of harmful toxic substances. Evaluation of the work of the PPS as part of three-layer building structures showed that under the plastered surface, the PPS is physically unstable. Even at a temperature of +20 °C, the amount of harmful substances emitted by the EPS produced by the Minsk plant for building products exceeds the MPC (maximum permissible concentration) by 2.5 times. According to the Center for Ecological Toxicology (Moscow), the content of chloroform, isopropylbenzene, ethylbenzene, xylene, naphthalene and other toxic substances in panels of residential buildings containing EPS as a heater exceeds the MPC from 10 to 100 times!
In the moistened heat-insulating material, favorable conditions arise for the decay of the wooden (or corrosion of the metal) frame and the softening of the gypsum-fiber sheet, since gypsum is not a waterproof material. The development of these processes will be indicated first in the form of “wet spots” inside the premises, and then mold will appear in the interior. Similar claims can be made to almost any type of three-layer panels, because steam always diffuses from a dense material into a porous one, but vice versa, it does not move.
Eventually:
It is easy to conclude that the change in the properties of expanded polystyrene from the impact of uncontrolled random factors is potentially dangerous if it is used as a building wall insulation. The use of PPS is also economically unprofitable if the period of operation of the building should exceed 10 years. For use in capital construction, such materials are needed, the properties of which best satisfy the set of requirements for environmental friendliness, thermal efficiency, fire and explosion safety, comfort and durability, reliability and maintainability imposed on them not only at the time of construction, but also during the operation of buildings.
Building material Fiber foam concrete - the choice of modernity!