Do you know the development history of physical concrete foaming agent
The physical foaming agent refers to a foaming agent in which the foaming agent solution introduces air into the solution through mechanical stirring such as high-speed stirring and compresses air to generate foam. Compared with chemical foaming agents, the process of preparing foam concrete by the physical foaming agent is to prepare foam in advance and then mix with concrete slurry, light aggregate, admixture, and other materials, and finally, cast mold curing to prepare foam concrete Sample.
The first generation: rosin blowing agent
Rosin foaming agent refers to rosin soap and rosin thermal polymer foaming agent, of which rosin soaps are widely used. Rosin soap is a metal salt of rosin acid, and its main component is sodium rosin (potassium). Its preparation method is to prepare rosin, lye, and additives by the heating reaction. Rosin thermal polymer foaming agent is the earliest foaming agent prepared, which is gradually banned due to the toxic phenol contained in the raw materials. Although the rosin-type foaming agent has a simple process and low price, due to its poor foaming capacity and foam quality, it is only used in foam concrete with a density of 600 kg / m3 or higher in practice.In the research process of rosin blowing agents, the earliest rosin blowing agent was the "Vinsol2" resin blowing agent developed in the United States in the 1930s.
Second generation: Synthetic foaming agent
Synthetic foaming agents were first used in the 1950s. Synthetic foaming agents can be divided into anionic, cationic, nonionic, and zwitterionic types according to the charging properties of surfactants. Foaming agents are mostly anionic surfactants. The characteristics of anionic surfactants are strong foaming capacity and larger foaming volume, but the disadvantage is that the foam stability is poor; the nonionic surfactants are not as foaming as the anionic ones, but the foam stability is better, Can be used as a stabilizer; the hydrophilic end of the cationic surfactant is a cation, and the charge is electrically equivalent to the Ca2 + in the cement, resulting in a charge repulsion in the cement slurry, so in the slurry The stability in the medium is poor; the foaming performance of the zwitterionic surfactant is better, and the quality of the prepared foam is better, but because of the slightly higher price, it is rarely used in the foaming agent.
The third generation: protein foaming agent
The effective components of protein foaming agents are natural proteinaceous substances, mainly extracted from animals and plants. The raw materials of animal protein mainly come from animal hoof angle, hair and blood gel, and the raw materials of plant protein include tea saponin and saponin. Compared with other types of foaming agents, protein foaming agents have the advantages of better foam stability, and the foam can exist for a long time, but the disadvantage is that the foaming ability is average. The foaming performance is easily affected by external factors, and the cost is higher than other types of blowing agents, so it is generally used in 200-500kg / m3 foam coagulation: soil.
The fourth-generation: composite foaming agent
The compound foaming agent is composed of materials with different functions. There are four main methods of compounding, which are a complementary method, a synergistic method, a synergistic method, and an increasing functional method. The principle of compounding is to use various types. The outstanding effect of the substance adjusts the function of the foaming agent to improve its foaming performance. Composite foaming agents are usually composed of foaming components and foam stabilizing components.
Americans have the longest history of research on blowing agents. At present, not only the technology is more advanced, but the exploration of blowing agent theory is also more in-depth. FWinik et al. Found that the alkyl carbon chain of the surfactant.
When the number of atoms is 12. and the carbon chain is linear, the foam stability prepared by Lonnie JameGray uses fluorine-containing surface-active substances to modify the anionic surfactant. The resulting foaming agent still has high stability at high temperatures.
Now, do you understand the history of the development of physical concrete foaming agents? In practical applications, we should choose the type that suits us according to the actual situation.
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