Foaming agent refers to all surface-active substances whose solutions can produce a large amount of foam through physical methods (stirring, compressed air, etc.) or chemical reactions under specific conditions. Foaming agent has high surface activity, can effectively reduce the surface tension of the liquid, and arranges the two-electron layer on the surface of the liquid film to surround the air, forming bubbles, and then developing a foam by a single bubble. The essence of the foaming agent is its surface activity. Because of the intense surface activity of the protein itself, it is possible to develop a foaming agent for the protein. When the protein is hydrolyzed, the large protein molecules of the longer peptide chain become a mixture of short-chain soluble small and medium molecules. After dissolving in water, it can form a colloidal solution with specific viscosity. The carboxyl, hydroxyl and other hydrophobic groups such as extended carbon chain hydrocarbon groups, as well as the asymmetry of the molecule, reduce the surface tension and promote the formation of the interface.
The peptide chains of these small and medium molecules stretch at the interface, the strong hydrogen bonding between the intergroup forms a flat protective net, which strengthens the interface, which promotes the formation and stability of the foam. Incomplete hydrolysis of proteins is a crucial factor in foam formation and stability. Compared with traditional physical foaming agents, chemical foaming agents, and synthetic surfactant foaming agents, the protein-based foaming agent is a current high-end foaming agent with better performance and better development prospects. Judging from the general trend of development, it has occupied an increasing proportion of applications in recent years. Although its price is relatively high, it is still accepted by the market due to its excellent performance, easy access to raw materials, and environmental protection.
What is the foaming agent used in foam concrete?
(1) The plant-based cement foaming agent
The main varieties of plant cement foaming agents are the two significant classes of tea saponin and saponin. In the strict sense, the main active ingredient of these two types of foaming agents for concrete is not protein but is similar to traditional synthetic foaming agents. There are significant differences compared to this. Besides, the main ingredients of these foaming agents are from plants, so they are still classified as plant protein foaming agents. Due to sufficient raw materials, the production and application of these two types of cement foaming agents have reached a considerable scale.
Plant-based cement foaming agent uses high-quality natural plant polymer materials as raw materials and is made through a series of complex chemical reactions. The product is a pale yellow pure transparent oily liquid. Insensitive to hard water, non-toxic, odorless, no sediment. PH value is neutral, non-corrosive cement, metal, and does not pollute the environment. The foaming agent has storage resistance, is not easy to deteriorate, has excellent foaming performance, is rich in foam, and is relatively stable. The practical application of the foaming agent to produce foam cement has the advantages of low consumption, low cost, and durable quality. It is widely used in floor heating decoration projects and roof insulation decoration projects, which can significantly save construction costs.
(2) Protein-based foaming agent
The performance of an animal protein-based foaming agent is comparable to that of plant protein foaming agent, and the foaming ability and foam stability are generally equivalent.Animal protein-based foaming agents are mainly divided into three categories: hydrolyzed animal hooves, hydrolyzed waste animal hair, and hydrolyzed blood gel. The animal cement foaming agent is selected from animal keratin and is prepared through a series of hydrolysis reactions, dissolution, dilution, filtration, and high-temperature shrinkage. This product is a dark brown viscous liquid with low impurity content, intense odor irritation, uniform quality, stable quality, good formability, and foam stability. Due to the high strength and foam stability of the foam surface formed using the foaming agent, the foam cement produced by the foaming agent has an independent closed state, and the bubbles do not communicate with the bubbles. The foamed cement products have excellent permeability resistance. Its one-time casting foam cement can reach more than 1.5m without collapse, which is suitable for the manufacture of foam concrete blocks, lightweight concrete panels, and partition walls.
Disadvantages of animal cement foaming agents
Due to the complicated production process, the product cost is high. Foaming agents have lower foaming properties than plant foaming agents, and foamed cement is used for more consumption. There is a specific pungent odor when used, and it will gradually disappear after being made into foam cement.