Advantages of foam concrete compared with aerated concrete

Comparing aerated concrete with foam concrete, its obvious advantage is that it has higher strength than foam concrete and uses less cement. The amount of cement used in aerated concrete is only 5% to 10%, while foamed concrete is mostly 100% cement, at least 50% cement. However, the comprehensive advantages of foamed concrete are far greater than those of aerated concrete, making it an attractive choice in the future market. Competition will still occupy a larger market share. There are five biggest advantages of foam concrete:
1. The advantage of cast-in-situ construction

Aerated concrete cannot be constructed on-site because it requires autoclaving. One car can bring the entire set of foam concrete equipment to the site, and seven people can pour 100 to 200m3 on site in one day. Cast-in-place roof insulation layer, cast-in-place floor heating insulation layer, cast-in-place self-insulating wall, cast-in-place exterior wall insulation wall, cast-in-place floor cushion, and cast-in-place core column are all the strengths of foam concrete, and It will play an important role in building insulation in the future. It is no exaggeration to say that the largest application of building insulation in the future may be cast-in-situ foam concrete.

Although the material cost of foam concrete is high, because it can be cast on site, it saves a lot of production energy consumption and product processing costs, and its density is low, and the total amount of raw materials used for production is small. This reduces the total cost and resolves its disadvantages, and the cost is lower than that of aerated concrete. Taking self-insulating walls as an example, the price of a cubic meter of aerated concrete in Beijing is 200 yuan. Including the masonry fee and freight, the total cost should not be less than 300 yuan. The total cost of cast foam concrete in the wall is only 130 yuan/m3. If we consider that due to its low density (aerated concrete 600~700kg/m3, cast-in-place foam concrete 300~400kg/m3), the wall can be thinned, reducing the cost. If the amount of insulation material is used, the cost of the cast-in-place foam concrete wall will be even lower. It clearly shows the advantages of pour-in insulation. Figure 5 shows the formwork of the foam concrete cast-in-place wall being removed.

2. Advantages of low water absorption

The water absorption rate of air-entrained concrete is as high as more than 45%, which has always been its major disadvantage. This disadvantage makes it difficult to paint, requiring the use of interface agents. Even if interface agents are used, engineering accidents such as hollowing, peeling, and cracking of the stucco layer often occur.

Foam concrete can freely control the water absorption rate by adjusting its closed cell ratio. Its general water absorption rate is about 20% to 25%, and low water absorption products are about 8% to 12%. Ultra-low water absorption Rate products can reach 2% to 5%. This advantage of low water absorption not only avoids the above-mentioned disadvantages of aerated concrete, but also fills the gap that aerated concrete cannot be used in alpine areas. At present, we have produced and applied ceramsite foam concrete blocks in Heilongjiang. Insulation is most needed in these places, and air-entrained concrete cannot be used due to high water absorption. I think that in areas such as Northeast China, Inner Mongolia, Qinghai, Xinjiang, and Tibet where aerated concrete cannot be used so far, foam concrete will make a big difference.
3. Advantages of low density and ultra-light

The density of air-entrained concrete is mostly 500-800kg/m3. There are very few products with a density lower than 500 kg/m3 and cannot be produced stably. The density is lower than 300 kg/m3. There are almost no products from m3. Due to the constraints of process technology, it is difficult to produce ultra-light products below 400 kg/m3 from aerated concrete. The current building energy conservation requires ultra-light products below 400 kg/m3, because their thermal insulation performance is better and it is more conducive to lightweight buildings.

At present, the widely used foam concrete has a density of generally 200-450 kg/m3, which just makes up for the shortcomings in the performance of aerated concrete. The two form market complementarities and dislocations. Figure 7 shows the ultra-light display of foam 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 half that of air-entrained concrete. This means that by using foam concrete to meet building energy-saving standards, the wall can be nearly twice as thin as that of air-entrained concrete, which can save a lot of material and increase the usable area.
4. Advantages of flexible technology and wide variety

Due to the limitations of autoclaving technology and equipment, aerated concrete is basically mainly made of blocks and strips, and other types of products Not yet, which reduces its application scope and market share to a certain extent.

Foam concrete can be used for various cast-in-place constructions and can also be produced using different processes. Currently, there are more than 10 types of foam concrete insulation products, and there will be dozens in the future. Foam concrete responds quickly to market demand and has strong adaptability. When the market demands a certain product, it can be produced quickly, or even a new product can be produced by changing a mold. This cannot be done with air-entrained concrete. For example, foam concrete can produce large-sized sandwich roofs and wall insulation panels. The current maximum size has reached 3000×6000mm, which cannot be achieved with air-entrained concrete. For another example, foam concrete can easily produce lightweight core-filling products and sandwich products. Neither can air-entrained concrete; for another example, foam concrete can easily produce ceramsite-reinforced products, colored products, special-shaped products, etc.Products, etc., air-entrained concrete cannot. This determines that foam concrete will occupy more application areas with its production flexibility.
5. Advantages of small investment and easy popularization

China’s current national conditions determine the production of building insulation materials. Small and medium-sized enterprises will still account for a considerable proportion, with costs of tens of millions of yuan at every turn. Investment is something they still cannot afford. The investment in aerated concrete generally costs more than 10 million yuan, which is difficult for small and medium-sized enterprises to implement.

The investment in foam concrete is very small, and a set of cast-in-place equipment does not exceed 100,000 yuan, which can facilitate construction. Product production lines generally cost between hundreds of thousands to several million yuan, which are much smaller than aerated concrete. This is very conducive to the promotion and implementation of foam concrete, and creates favorable conditions for its popular application in building insulation.

In summary, the following conclusion can be drawn: As the same type of insulation materials, aerated concrete and foam concrete have their own advantages, but foam concrete has more advantages. In the density grade range of B06 to B07, air-entrained concrete will have an advantage due to its good strength. In the range of cast-in-place and density levels below B05, foam concrete will have an advantage. The two can achieve complementary advantages in the market. From the perspective of total application volume, foam concrete will definitely exceed aerated concrete in 3 to 5 years. </p