Inorganic thermal insulation materials that can replace organic thermal insulation materials are mainly foamed concrete aerated concrete, foamed glass, mineral wool rock wool, vitrified microbeads, ceramsite, etc. These inorganic materials will occupy a certain proportion in the future building insulation market, realizing the complementary advantages of various inorganic materials, but foamed concrete has more advantages. With its advantages, foamed concrete will be used in these inorganic insulation materials. Stand out and occupy the main position of building insulation.
Advantages of foamed concrete compared with aerated concrete
Compared with foamed concrete, aerated concrete has the obvious advantage of higher strength than foamed concrete and less cement consumption. The amount of cement in aerated concrete is only 5%-10%, while most of the foamed concrete is 100% cement, and at least 50% or more cement is required.
However, the comprehensive advantages of foamed concrete are far greater than that of aerated concrete, so that it will still occupy a larger market share in the future market competition. There are five biggest advantages of foamed concrete:
(1) Advantages of cast-in-place construction
Aerated concrete cannot be constructed on site due to autoclave. A full set of equipment can be brought to the site with a single car using foamed concrete, and seven people can cast 100-200m3 in a day. Cast-in-place roof insulation layer, cast-in-place floor heating insulation layer, cast-in-place various self-insulation walls, cast-in-place exterior wall insulation wall, cast-in-place floor cushion, cast-in-place core column, are all the strengths of foamed concrete. And it will play an important role in the future building insulation. It is no exaggeration to say that the largest application of building insulation in the future may be cast-in-place foamed concrete.
Although the material cost of foamed concrete is high, because it can be cast in place, it saves a lot of production energy consumption and product processing cost, and its density is low, and the total amount of production raw materials is small. It reduces the total cost and resolves its disadvantages, but the cost is lower than that of aerated concrete. With self-insulating walls, the wall can be thinned and the amount of insulation materials reduced, so the cost of cast-in-place foamed concrete walls is even lower, which obviously shows the advantages of pouring insulation.
(2) The advantage of low water absorption
The water absorption rate of aerated concrete is as high as 45%, which has always been a major disadvantage of it. This disadvantage makes painting difficult and requires the use of interface agents. Even when the upper interface agent is used, engineering accidents such as hollowing, peeling, and cracking of the paint layer often occur.
Foamed concrete can freely control the water absorption rate by adjusting its closed cell rate. The general water absorption rate is about 20% to 25%, the low water absorption rate product is about 8% to 12%, and the ultra-low water absorption rate product can reach 2 %～5%. This advantage of low water absorption not only avoids the above-mentioned drawbacks of aerated concrete, but also fills in the gap that aerated concrete cannot be used in alpine regions. At present, we have produced and applied ceramsite foamed concrete blocks in Heilongjiang. In these places, insulation is most needed, and aerated concrete cannot be used due to its high water absorption rate. I think foamed concrete will do a lot in areas where aerated concrete cannot be used, such as Northeast China, Inner Mongolia, Qinghai, Xinjiang, and Tibet. Figure 6 shows the condition of water droplets on the surface of foamed concrete ultra-low water absorption products.
(3) Advantages of low density and ultralight
The density of air-entrained concrete is mostly 500～800kg/m3. There are few products below 500 kg/m3, which cannot be produced stably, and there are almost no products below 300 kg/m3. Due to technological constraints, it is difficult to produce ultra-light products with aerated concrete below 400 kg/m3. At present, energy-saving buildings require ultra-light products below 400 kg/m3, because their thermal insulation performance is better, which is more conducive to building lightweight.
At present, the widely used foamed concrete generally has a density of 200-450 kg/m3, which just makes up for the lack of performance of aerated concrete, and the two have formed market complementarity and dislocation. Figure 7 shows the ultra-light display of foamed concrete.
The thermal conductivity of the leading aerated concrete products B05～B07 is 0.14～0.18w/m·k, while the thermal conductivity of the leading foam concrete products B02～B04 is only 0.065～0.10 w/m·k, which is only equivalent to Half of aerated concrete. This means that if foamed concrete is used to meet building energy efficiency standards, the wall can be nearly twice as thin as aerated concrete, which can save a lot of materials and increase the use area.
(4) Advantages of flexible process and many varieties
Due to the limitation of autoclaved technology and equipment, aerated concrete is basically based on two major products: blocks and slats, and other types of products are not available, which reduces its application scope and market share to a certain extent.
Foamed concrete can be used for various cast-in-place constructions, and products can also be produced by different processes. At present, there are more than 10 kinds of foamed concrete insulation products, and there will be dozens of them in the future. Foamed concrete responds quickly to market demand and has strong adaptability. When the market demands a certain product, it can be produced quickly, and even a new product can be produced by changing a mold. Aerated concrete cannot do this. For example, foamed concrete can produce large-size sandwich roofs and wall insulation boards. The current maximum size has reached 3000×6000mm, but aerated concrete can’t. For another example, foamed concrete can easily produce lightweight grouting products and sandwich panels. Core products and aerated concrete cannot be used either; for example, foamed concrete can easily produce ceramsite-reinforced products, colored products, special-shaped products, etc., neither can aerated concrete. This determines that foamed concrete will occupy more application areas with its production flexibility.
In summary, the following conclusions can be drawn: Aerated concrete and foamed concrete have their own advantages as the same type of insulation material, but foamed concrete has more advantages. In the density range of B06～B07, aerated concrete will have an advantage due to its good strength. In the cast-in-place and density range below B05, foamed concrete will have an advantage. The two can realize the complementary advantages of the market. From the perspective of total application, foamed concrete will definitely surpass aerated concrete after 3 to 5 years.
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