Introduction of Concrete release agent
Keywords
Concrete release agent, release agent
Concrete release agent refers to a substance smeared on the construction formwork before concrete pouring, so that the formwork will not stick to the concrete surface after pouring, not easy to remove the formwork, or affect the finish of the concrete surface. Its main function is to form a film on the surface of the formwork and the concrete to separate them, so it is also called a release agent.
In short, it refers to the additives used to make concrete products quickly get out of the mold, so that they can be quickly applied to the next process.
Mechanism
The separation of concrete and formwork must overcome the adhesion between the formwork and the hardened concrete or the cohesion of the concrete surface. The release agent reduces this effect through chemical or physical reactions.
Physical lubrication: The release agent plays a lubricating role between the formwork and the concrete, weakening the affinity between the two to play a release role.
Film-forming isolation: The release agent is coated on the surface of the template to form a film, and the film is used for isolation to release the mold.
Chemical action: The release agent has a certain chemical reaction with some minerals or ions in the fresh concrete to generate a substance with an isolation effect, thereby playing a release role.
No matter what the form of the release agent is, whether it has any of the above single or composite functions, in essence, a thin layer of hydrophobic substances exists between the concrete and the formwork, forming an easy-to-separate interface. Demoulding.
TypeS
Pure oil release agent The main components of this type of release agent include mineral oil, animal oil, vegetable oil and a mixture of various oils. The main components of such release agents include mineral oil, animal oil, vegetable oil and mixtures of various oils. But at present, most of them use mineral oil, that is, lubricating oil with low viscosity and good fluidity in petroleum industry products, mechanical oil, waste oil and so on.
Emulsified oil release agent Emulsified oil release agent is also known as emulsion release agent. There are two types of water-in-oil emulsions (W/O) and oil-in-water emulsions (O/W). Water-in-oil emulsions are made by suspending water in the oil phase through emulsification technology. They are widely used in molds or wooden molds with wet surfaces. For steel molds, rust inhibitors must be added to reduce color defects and pockmarks.
Saponified oil release agent This type of release agent is often used in wood formwork, and its main component is an emulsion formed by oil (such as mineral oil, animal and vegetable oil) plus alkali through saponification reaction, and soap emulsion can also be used. Its demoulding effect is mainly to use the saponified emulsion to lubricate and isolate the concrete and the wooden form. The raw materials of the soap mold release agent are readily available, the production cost is low, the preparation process is simple, and the use and operation are convenient, and it is suitable for wooden molds, ground molds, and the like.
Paraffin-based mold release agents Paraffin-based mold release agents are mainly emulsion-type paraffin-type mold-release agents in China. Rain resistance. However, when the paraffin-based mold release agent is coated too thickly, paraffin traces will be left on the concrete surface, which will affect the appearance and secondary decoration of the product surface.
Chemically active release agent Chemically active release agent mainly has fatty acid as its activating ingredient. It can react slowly with free alkali (calcium hydroxide) in concrete when it is applied to the formwork to generate water-insoluble fatty acid salt. It can prevent the consolidation of the concrete in contact with the formwork, form an isolation layer between the formwork and the concrete, and play the role of demoulding.
Synthetic resin type release agent The main components of this type of release agent are 1~2 kinds of methyl silicone resin, epoxy resin and unsaturated polyester resin, and the release agent has a very good release effect.
Composite water-based mold release agent
At the same time, it has the functions of lubricating, polishing and repairing, improving the flatness and smoothness of the surface of concrete products.
Main material
Alumina, sodium hexametaphosphate, thiourea, ammonium persulfate, paraffin, paraffin emulsifier, rust inhibitor, etc.