What is foam glass and who needs it in the modern market? Does it make sense to pay so much money for it, or is it easier to use other, less expensive materials? From this article you will find out when it is advisable to go broke on foam glass, and when you simply cannot do without it..
Not so long ago, a new insulation material appeared on the modern domestic construction market – foam glass. Construction forums were literally packed with questions that sometimes even experienced practitioners cannot give answers to. And this despite the fact that the first sample of foam glass was produced in the USSR back in the 30s of the last century (in the USA, the production of this insulation was a good ten years late).
So why has such a wonderful, as its manufacturers positioned, heat-insulating material remained unknown for a Russian builder for so long? The question is most likely in the solvency of the domestic buyer. Depending on the manufacturer, the cost of a cubic meter of foam glass can reach 20-30 thousand rubles. Let’s try to make a comparative description of this material and its direct competitors, and in the process already determine when it is worth using prohibitively expensive foam glass, and when it is possible to do with relatively inexpensive analogues..
Granulated foam glass
The main competitor of granulated foam glass is the well-known expanded clay.
The comparative characteristics of these materials are given in the table:
Specifications Granulated foam glass Expanded clay Bulk density, kg / m3 200 200 Thermal conductivity in the embankment at 20 ° C, W / (m? K) 0.06-0.068 0.1-0.18 Water absorption by volume,% 1.7-4 24 Compressive strength in a cylinder, MPa 0.5-1.1 1.4 Granule diameter, mm 5.0-40.0 5.0-40.0 Frost resistance by weight loss, cycles 15 15 Price per m3, rub. 1400 4000
In order to clearly demonstrate the advantages of this or that material, as well as show what the buyer should be guided by when choosing between these two heaters, we will give a specific example.
Let’s say we need to insulate the roof, get some 2.50 m2?K / W. The average value of the thermal conductivity of the expanded clay pillow is 0.14 W / (m? K), which means that a 35 cm layer will be needed to achieve the necessary thermal insulation properties:
- 2.50 m2?K / W x 0.14 W / (m? K) = 0.35 m
Which is at a price of 490 rubles. for each square meter:
- 0.35 m3 x 1400 rubles / m3 = 490 rubles.
Granular foam glass will need a little less, or rather 17 cm:
- 2.50 m2?K / W x 0.068 W / (m? K) = 0.17 m
But on the other hand, at the price for each meter, you will have to pay not 490 rubles, but 680, which is 190 rubles. more:
- 0.17 m3 х 4000 rubles / m3 = 680 rubles.
That is, on a roof of 100 m2 the savings will amount to no less than 19,000 rubles:
- 100 m2 x 190 rubles / m2 = 19000 rub.
Now let’s look at the percentage of water absorption by volume. For expanded clay, this figure is downright indecent 24%. In other words, when expanded clay gets wet, not only will it lose its thermal insulation capacity, but it will also significantly add weight, and if we take into account that the expanded clay pillow already weighs twice as much, then when wet, the weight of water should be added to these indicators. 24% is 240 liters per cubic meter, that is, 240 kg. This means that, all other things being equal, the weight of a wet expanded clay insulation in our case will be 154 kg / m2:
- (200 kg? M / m3 + 240 kg? M / m3) x 0.35 m3 = 154 kg / m2
Whereas foam glass is only 40.8 kg / m2, that is, 3.8 times less:
- (200 kg? M / m3 + 40 kg? M / m3) x 0.17 m3 = 40.8 kg / m2
The designer lays down the strength (and therefore the cost) of the walls and foundations based on these extreme values. In other words, choosing foam glass granules as a heater, a smart owner, having paid, at first glance, more, saves on the thickness of the walls and foundation, on possible repair work associated with roof leaks..
It would be another matter if it was not the roof that had to be insulated, but the interfloor ceiling, where the chances of the insulation getting wet would tend to zero. The use of granular glass there would be simply economically unreasonable.
Foam glass sheet
Sheet foam glass has its own analogue – it is the well-known expanded polystyrene. Let’s see the table:
Specifications Foam glass sheet Expanded polystyrene with a density of 25 Density, kg / m3 160 25 Thermal conductivity coefficient, W / (m? K) 0.068 0.041 Vapor permeability 0.001-0.005 0.05 Working temperature, ° С from -260 to +485 from -180 to +80 Autoignition temperature, ° С Non-combustible material 491 Compressive strength, kg / cm2 7.0-16.0 0.08 Water absorption in 24 hours, in% of volume 3 3 Lifetime Over 100 years Under 50 Price per m3, rub. 12000 1800
Judging by the comparative data, it becomes clear why expanded polystyrene is used everywhere, and very few people have heard about sheet foam glass..
Sheet glass is 6 times heavier than polystyrene, has a higher thermal conductivity coefficient, and with all this it costs 6-7 times more. The benefits of using styrene foam are visible to the naked eye. But if it were that simple, foam glass would simply not be produced..
Let’s try to figure out why and most importantly when experts prefer to pay 6 times more for foamed glass plates.
First, let’s pay attention to the service life of expanded polystyrene. Up to 50 years, not so little. Most plaster topcoats, with all their desire, will not be able to boast such longevity. What if we take marble? Granite? Or just high quality façade tiles? Or any other capital material that has a life span of centuries? Indeed, erecting a multi-storey building, engineers lay in it far from 50 years of service. Then, when the expanded polystyrene simply collapses from time to time, the foam glass continues to serve.
So, foam glass should be used if the insulation is used in combination with capital materials, the service life of which reaches 100 years.
Secondly, we look at the operating temperatures. Expanded polystyrene begins to break down at temperatures above 80 ° C, while the heating temperature, for example, of a steam room, very often exceeds 100 ° C. Despite the fact that foam glass is much more expensive, it is necessary to use it in such cases, since there is often simply no choice. Mineral wool takes moisture, wood occupies a significant space, polyurethane foam, which releases hydrocyanic acid during combustion, in general, in such fire-hazardous places as a bathhouse, you must not let a cannon shot. So it turns out that, despite its cost, foam glass is still the best choice..
Most often, foam glass is used when any other options are eliminated by the exclusion method due to their operational properties..
The third reason is environmental safety. Whatever the foam manufacturers say, it is harmful. It’s just that in our country they have not yet learned to value their health. And that which does not kill us immediately is considered quite safe. Meanwhile, the free styrene contained in such a heater is released and poisons us every hour. So those who value their health much more than money buy absolutely safe foam glass for humans (provided that they have this money, of course).
People who care about their health choose foam glass, considering its environmental safety.
Foam glass blocks
The opponent of foam glass blocks is considered to be popular today and also far from cheap aerated concrete. Both the one and the other material is capital, with a service life of over a hundred years. Both are not afraid of high temperatures and have excellent structural characteristics. But at the same time, the simplest domestic foam glass is 4 times more expensive than imported samples of aerated concrete.
Those wishing to understand the reasons should pay attention to the fact that the water absorption of foam glass confidently tends to zero, while porous aerated concrete saturates moisture like a sponge.
Specifications Foam Glass Blocks Aerated concrete Density, kg / m3 200 400 Thermal conductivity coefficient, W / (m? K) 0.07 0.125 Vapor permeability 0.001-0.005 0.2 Compressive strength, MPa 4 2.50 Water absorption in 24 hours, in% of volume 3 thirty Lifetime Over 100 years Over 100 years Price per m3, rub. 22000 4300
More often than not, it doesn’t matter at all. Most often, but not always. For example, on the dome of the Novosibirsk Opera House, the aerated concrete structure so saturated moisture that not only lost its thermal insulation capabilities, but also significantly gained weight. The condition of the building standing in millions of rubles became, to put it mildly, emergency. The only possible solution was to replace the gas blocks with its foam glass counterparts..
If you look closely, then, having half the density, foam glass surpasses aerated concrete in its thermal insulation characteristics by 80%, and structural by 60%. And this is very important, because in cases where the use of other construction materials is simply impossible or economically unreasonable, experts resort to construction technologies based on the use of foam glass products.
Today, foam glass blocks are used for the manufacture of swimming pools, baths, roof elements and domes. In a word, wherever the maximum possible combination of lightness and structural reliability is vital, with maximum thermal insulation characteristics. In other cases, the customer uses less reliable, but cheaper materials..
Foam glass is a truly environmentally friendly, reliable modern material. And let the developer not be intimidated by its price. Sometimes an accurate engineering calculation proves the deceitfulness of superficial reasoning and puts forward foam glass products as the most acceptable and economically viable option..