Table of Contents
Reliable, warm and ecologically safe house – dream of each person. However traditional building materials, such as brick, stone or tree are available not to all now. How to fulfill dream and to save means? Today there is set of alternative options. Quickly wall gas-concrete blocks will help to build the desired house: the sizes and piece prices, important parameters and responses of experts will be useful for right choice and purchase of this material.
What is gas concrete
In the aspiration to simplify process of construction of buildings and to make building materials more available producers propose new solutions. One of them is creation of foam mortar. The gas concrete – one of kinds of porous concrete, in fact, is artificial stone with spherical cells.
Do it of cement, quartz sand and specialized blowing agents (aluminum paste or suspension). Sometimes plaster, ashes, lime are in addition added. Then weight is subjected to long heat treatment under high pressure in autoclaves. Owing to chemical reaction the cement slurry foams and stiffens with already created time.
Choosing gas-concrete blocks (the sizes and piece prices will be considered below), it is necessary to consider the following criteria:
- total load on walls;
- heattechnical characteristics;
- proportionality of laying;
- ways of simplification of process of construction;
- the gas-block sizes depending on design dimensions of the building;
Technical characteristics and physical properties of gas-concrete blocks
If you have made the decision to use gas-concrete block in construction it is necessary to have idea of its main technical characteristics. It will help to make optimum choice and to avoid the irrational financial investments.
Basic sizes. Blocks from gas concrete have the different sizes, it allows to calculate their necessary quantity more precisely. Are the most demanded: 600×300×200, 600×300×250, 400×300×200, 600×300×300, 400×300×300, 600×400×300, 400×400×300 and 500×400×300 mm. Knowing the sizes it is possible to calculate how many pieces of gas-blocks cubed and, respectively, how many they are necessary for building construction with the set technical parameters.
Density. The brand on density is measured in kg/m³. According to requirements (Concrete cellular) the gas concrete is subdivided on density into heat-insulating (D300-D500), constructional and heat-insulating (D500-D900) and constructional (D1000-B1200). The more density of gas-concrete block, the higher it bearing capacity.
Strength class. This indicator defines what axial pressure can sustain this block. For example, the strength class of B2.5 allows to use such block in construction of load bearing walls up to 20 m high. Values of indicators following: B1.5, B2.0, B2.5 and B3.5.
Comparative table of characteristics of the gas-block and other materials:
|Technical characteristics||Ceramic brick||Lime sand brick||Wall from porous large-size ceramic blocks||Gas-concrete wall from blocks of industrial production|
|Compression strength, kg/m²||125||150||128||15-30|
|Average density, kg/m³||1350||1750||830||400|
|Heat conductivity, W/(m*°J)||0.40||0.95||0.21||0.1|
|Water absorption, %||13||13||12||>30|
|Frost resistance, cycles||35||35||50||25|
|Normative wall thickness, m||0.52||0.52||0.38||0.40|
|Speed of construction of wall of normative thickness, hour/m²||>3||>3||∼1.3||∼0.88|
Coefficient of thermal conductivity. This indicator has such values: 0.096, 0.12, 0.14 and 0.17, also means ability of warmer room “to share” the heat with cold. The it is higher than a coefficient, the more heat emission. When determining of the coefficient which is most suitable for you it is necessary to consider humidity surely.
Frost resistance. The indicator of frost resistance is measured in cycles, and for gas-concrete blocks from 25 to 100 matters. For comparison, the brick has up to 50 cycles of frost resistance.
Drying strinkage. This indicator is measured in mm/m and has to make no more than 0.5, otherwise you risk to see more shrinkage cracks on walls of the house.
Helpful advice! For uniform drying in order to avoid shrinkage cracks specialists recommend to humidify the constructed gas-concrete structures that drying happened evenly.
Gas-concrete blocks: pluses and minuses, responses of experts
Let’s understand what does gas-concrete blocks such demanded and popular in the construction industry and what doubts arise at their use?
Advantages of gas-concrete blocks:
- gas-concrete blocks are simple in processing: the opening is easy to saw, drill them in them, to hammer nail, to plane necessary form;
- they have small weight at impressive dimensions. It considerably increases the speed of work and reduces labor input in construction;
- it is ecologically safe material which is made of the natural components which are not allocating hazardous substances;
- gas-blocks have the high level of heatsaving. Thanks to porosity blocks from gas concrete almost do not carry out heat. It reduces costs of heating of the house in the winter, and protects from overheating in the summer;
- sound-proof properties provide cells with air. External noise will remain behind walls of your house. Especially well they absorb low-frequency noise;
- the gas concrete does not burn – it is the fire-resistant material capable for a long time to sustain direct influence of naked flame. The fire resistance gives it mineral structure;
- gas-silicate concrete is frost-resistant. Degree of frost resistance depends on technical characteristics of separate blocks.
Speaking about pluses and minuses of gas-concrete blocks, it is worth mentioning also their shortcomings to which it is necessary to pay attention when choosing this material for construction:
- the gas concrete consistency value, the lower it heat-insulating properties is higher;
- gas-concrete blocks with a density below 500 kg/m³ can be used rather as thermal insulation material. And here the consistency value of 500 kg/m ³ has boundary definition. Opportunity to use masonry units in load-carrying structures decide on such density by producers and test results;
- gas-concrete material is not elastic. In this regard at deformation of the base the wall from gas-blocks can crack. Therefore porous concrete structures are advised to build on monolithic continuous footing that can entail construction rise in price;
- because of porosity swore for fastening on walls of aerated concrete constructions of massive designs, normal fixtures will not approach. It is necessary to get special – for porous fragile structures that can also entail additional expenses;
- when laying porous blocks use cement and sand or special glue solution. In the first option heatloss increases by 25%, in the second – for 10%. Besides, heatresilience also falls because of use of crossing points and the reinforced belts. Thus, some experts consider that producers of gas-concrete articles have exaggerated statements for high heatsaving of this material as through laying seams there are heatlosses which are not considered in technical characteristics;
- the gas concrete absorbs moisture therefore in such material structure it is necessary to do steam barrier. The anti-steam effect by means of primer of deep penetration and stucco work is reached.
Helpful advice! For construction of the house with bearing capacities and good heat insulation it is necessary to choose gas-concrete blocks with density of 500 kg/m³, to take care of the strong base and steam barrier and also to use special thin layer glue for laying.
Gas concrete or foam concrete: that it is better
Both materials have similar physics and technology properties. Foam concrete has honeycomb too, it is produced from cement and sand mix with addition of foaming agent. The difference with gas concrete consists that foam concrete hardens in the natural way, and gas concrete – by means of heat treatment. Also for these materials different foaming agents are used.
Defining, what is better: gas-blocks or foam concrete blocks, it is necessary to know that the manufacturing techniques of foam concrete blocks are simple and does not demand industrial conditions. Therefore it is possible to make them on the portable equipment directly on building site. Such availability not always suits consumers: unfair producers often are engaged in production of foam concrete blocks that significantly influences product quality.
Gas-blocks are produced on large enterprises which adhere to necessary normative indicators.
It is important! Upon purchase of foam-concrete blocks from small producers work to check necessary allowing documents and certificates of quality.
The block from foam concrete can have toxic properties as process of hardening happens in the natural way and chemical processes can come to the end not up to the end. Processing of gas-blocks in autoclaves guarantees completeness of chemical process and ecological security of product.
Different methods of production also influence mechanical strength of the compared building materials. At the identical density the gas concrete is stronger than foam concrete. For example, at the density of 500 kg/m³ the gas concrete can be used as load-carrying structures, and foam concrete at such indicator can be used only as heater.
Moisture absorption and frost resistance breaks a set of these construction materials too. Gas-blocks absorb more moisture that influences indicators of heat emission and frost resistance. However this problem is solved with the help of stucco work.
Besides, the sizes of foam concrete blocks are not always standard. Foam concrete crumbles therefore in processing it is not so pliable as the gas concrete and in the course of work can crumble.
Considerable advantage of foam concrete blocks in the price. 1 m³ will be cheaper than blocks from foam concrete, than from gas concrete. The price is influenced by the production cost, production equipment making components and the applied technologies.
Thus, unambiguously to tell that it is better for construction of the house: gas concrete or foam concrete – it is impossible. The choice of this or that construction material depends on the purpose of its application, quality of materials and observance of production processes at its production.
How to calculate the number of gas-blocks for construction
Not to gain excess amount of construction materials it is possible to make approximate calculation of necessary number of gas-blocks.
For this purpose it is possible to use the following formula:
(LхN-Spr)х1.05хB = V, where
- L – total length of gas-concrete walls, m;
- N – the average height of gas-concrete walls, m;
- Spr – the total area of window and door openings, m²;
- 1.05 – the coefficient considering stock of 5% for undercutting;
- B – thickness of blocks, m;
- V – volume of necessary quantity of gas concrete, m³.
Proceeding from formula, it is possible to make the following table of calculation of number of gas-blocks cubed:
|Sizes of gas-blocks, mm||Pieces cubed|
Such calculation approximate also has rather advisory nature. On the websites of producers and sellers of gas-concrete blocks it is possible to find online calculators for necessary calculations. It is also possible to calculate base bid taking into account the sizes of gas-blocks and piece price at once.
Making purchase it is necessary to take an interest in the documents confirming quality of goods. Useful will also be to check products for external damages (it can affect properties of gas-blocks during operation). The overview of types, technical characteristics, properties, the sizes and piece prices of gas-concrete blocks surely will help to make to you right choice and soon to enjoy own cozy and inexpensive dwelling.