Current problems with foamed concrete
Since the research results of foamed concrete and its application technology are mostly reflected in the form of patents at home and abroad, there is a lack of complete sets of equipment for the production of foamed concrete in China. There is no complete data and experience accumulation, and there is a lack of theoretical guidance for construction. Therefore, in actual construction, due to factors such as materials, construction methods, and management, the superior performance of foamed concrete is not fully reflected, and some problems often occur. , especially showing some shortcomings in performance:
(1) Low strength: The compressive strength of foamed concrete is low, which is not conducive to engineering applications and makes the transportation of products more difficult. ;
(2) Cracking: The surface of foamed concrete is easy to crack, leading to the absorption of a large amount of external moisture;
(3) Poor water resistance: Generally, the dry density is 300~1000kg/m3 The volume water absorption rate of foamed concrete reaches 10% to 30%, and the mass water absorption rate reaches 10% to 50%. The water absorption rate increases with the decrease in dry density or the increase in the amount of introduced bubbles, which is more likely to cause freeze-thaw phenomena and affect The use effects and application fields of foam concrete. There are many technical measures to reduce the water absorption of foamed concrete, such as adding hydrophobic agents, coating waterproof materials on the surface, and surface treatment of the mixed materials (such as surface "wrapping" of added porous materials to make Its pores are "isolated" from the slurry, thereby reducing water absorption).
In addition, the current preparation method of foamed concrete still mostly uses physical foaming method, but it has the problems of unstable foam, high foaming agent price, complex equipment, etc. The construction is difficult, and the foam pore sizes are uneven, the one-time investment is high, and it is not conducive to large-scale promotion.
Production and application prospects of foamed concrete
At present, domestic foamed concrete products are divided into two categories: cast-in-place and prefabricated. Its main application field is cast-in-place. In the domestic market, cast-in-place foam concrete is mainly used for roof insulation layers, floor heating insulation layers and some cushion layers. Most production and construction equipment are continuously feeding, mixing, conveying, and pouring, that is, the four steps of feeding, mixing, conveying, and pouring are At the same time. In order to prevent a large amount of foam from being broken by long-term stirring when the tanker truck is driving to the construction site, a small foaming machine should be placed on the construction site to transport the foam to the cement (sand) slurry containing evenly stirred cement (sand) slurry according to the mix ratio. Mixed in a tanker and finally poured. For foamed concrete factory-based prefabricated products, the production process and quality control are relatively simple. The above process can be used for reference, but a reasonable mix ratio and curing system need to be adopted. It is recommended that medium- and high-density foamed concrete be mixed with appropriate Light aggregate to solve shrinkage and cracking of products.
Compared with foreign countries, the overall scale of foam concrete products in my country today is smaller, the technical level is not high, and there is a lack of leading products for bulk applications [8]. We firmly believe that with the technological advancement of my country's foaming agents and foaming machines, the establishment of national or building materials industry standards, and the improvement and perfection of construction technology, coupled with the many functional advantages of the foamed concrete material itself and the international development of the low-carbon economy Trend, my country's foam concrete market prospects will be broader. In addition, using foamed concrete to replace the currently used foam plastics as fireproof insulation materials is a new market growth point.
</p
微信扫一扫打赏
