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Review of research on concrete foaming agent

wallpapers Industry 2020-04-16

With the introduction of energy-saving and green building concepts in Goaniu, the building insulation material industry has a broad market. Light foam concrete with good heat insulation effect and light quality is vigorously promoted and used in the field of insulation materials. Become an urgent task. However, most of the concrete foaming agents currently on the market have the problem of poor foam quality when they are applied to lightweight foam concrete. Therefore, it is very important to explore the pros and cons of the foaming performance of various foaming agents and to understand the effect of various foam stabilizing substances on the modification of the foaming agent.

The thermal insulation performance of foam concrete mainly depends on the small closed air bubbles inside, so it is very important for foam concrete to prepare good quality foam. The performance of the foam depends on the foaming agent. A foaming agent with excellent performance can produce foams with small foam diameter, concentrated size distribution, and long life. Therefore, the foaming agent has become the key technology in the production of this insulation material. The earliest concrete foaming agent, "vino," was invented in the United States. Since then, countries have begun to introduce and continue to study. Nowadays, with the development of science and technology, various new materials continue to emerge, and concrete foaming agents have also developed and expanded. Up to now, there have been many types of concrete foaming agents. According to the foaming principle, these foaming agents can be divided into chemical and physical foaming agents.

The chemical concrete foaming agent

The chemical concrete foaming agent refers to a substance that the foaming agent mixed into the cement slurry will generate a chemical reaction and generate bubbles in a short time. General chemical blowing agents refer to aluminum powder, hydrogen peroxide, etc., the latter of which is more widely used. The process of preparing foamed concrete by the chemical foaming agent is to mix the chemical foaming agent with the cement slurry uniformly, the foaming agent will react in a short time to release gas, and the gas will gradually expand and form in the concrete slurry Bubbles, because of the slurry, the bubbles will only expand to a certain size, and then the concrete slurry gradually hardens and eventually solidifies the bubbles inside the concrete.

The advantages of chemical foaming agents are low requirements for foam stabilizers, easy preparation, and ultra-low density foam coagulants. However, the shortcomings of chemical foaming agents are also obvious. Because the foaming process of the foaming agent cannot be accurately controlled, the uniformity of the size of the bubbles generated by the chemical reaction inside the concrete is poor, and the bubbles are easily connected in the concrete, resulting in Foam concrete samples have low strength and poor thermal insulation.

The 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 characteristics of the physical foaming agent are that the prepared foam has a long service life, the foam diameter is generally less than 1 mm, and the foam size is relatively consistent. In addition, the foam is not easily broken in the concrete slurry to form atmospheric pores or communication pores.

Physical foaming agents are mainly composed of surfactants. With the development of new types of surface-active substances, new types of surfactants continue to emerge. Some new surfactants have more excellent foaming capabilities, making concrete foaming agents continuous Innovative, has so far developed to the fourth generation.

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