How to use foaming agent to prepare foamed concrete

Overview of foam concrete

Foamed concrete is a foaming agent that is fully foamed mechanically by the foaming system of the foaming machine, and the foam and cement slurry are evenly mixed. Then use the foaming machine pumping system for cast-in-place construction or mold forming, and a new type of lightweight thermal insulation material formed by a large number of closed-cell thermal insulation materials. As a new type of energy-saving and environmentally-friendly building material, scholars at home and abroad have conducted a lot of research and development on it, making it widely used in wall materials. Advantages: low density, light weight, good heat insulation, sound insulation, and seismic performance.

1. Foam production is commonly known as "foaming", the specification is "foam", and the main equipment is a foaming machine.

1.1 Foaming process The foaming process is to dilute the high-solubility foaming agent 20 to 30 times with water to become the foaming agent diluent, and then pump it into the foaming machine to form foam through the action of high pressure air.

1.2 Foam quality control After the variety and quality of the foaming agent are determined by testing, the quality control of the foam does not need to be determined by the testing of the foam concrete, but the quality can be controlled only through the measurement of the on-site foam meter. Foam quality control items are mainly its stability and water content. Both of these can be measured by controlling the bleeding and settlement distance respectively.

(1) Settling distance: Mainly represents the stability of the foam. After the bubble bursts, it will cause the volume of the bubble to decrease and cause sedimentation. By measuring its settlement distance, its stability can be known. The foam settlement distance of the wall shall not exceed 90mm within 1h.

(2) Bleeding rate: Mainly represents the water content of the foam. The greater the water content of the foam, the greater the bleeding volume. The greater the water content, the worse the quality of the foam, which means that when the amount of foam decreases and the water content increases, the more foam water will cause the porosity of the foam concrete to decrease and increase the capillary, foam concrete water absorption and The increase in thermal conductivity affects its usability. The wall reflects pouring, and its 1h bleeding rate is less than 90%.

(3) Bubble diameter: The diameter of the bubbles in the foam of the wall embodiment is mostly 1~2mm, a few are 2~3mm and 0.5~1mm. If the bubble diameter is too large (greater than 3mm), it is unqualified. If 60% of the bubbles are less than 0.5mm in diameter, Treated as unqualified.

1.3 Foam quality control factors

The production of high-quality foam is not only determined by the foaming agent, but also by the foaming machine, dilution water, and ambient temperature. Therefore, to obtain high-quality foam, comprehensive and comprehensive quality control should be carried out from the following aspects.

(1) Control of blowing agent. Foaming agent has an effect on the settlement distance, bleeding rate and bubble diameter, but has the greatest influence on the settlement distance. The foaming agent made of high-quality foam has a small bleeding rate while ensuring a high foaming ratio. In addition, even if different foaming agents use the same foaming machine, their bubble diameters are also different. Generally speaking, the higher the viscosity of the blowing agent, the finer the production. Foaming agents have different foam diameters due to different types of surfactants. Some surfactants produce dense foams, while others are not fine.

Therefore, it is very important to choose a suitable blowing agent. At present, there are many kinds of foaming agents on the market, and various tests should be used to judge their pros and cons, rather than relying on the instructions and feelings.

(2) Control of the foaming machine. The foaming machine has the greatest influence on the bleeding rate, bubble diameter and foaming ratio, and has little influence on the settlement distance. The number of foaming does not belong to the foam quality, but the foaming quality agent, which is not discussed here. The air compressor pressure of the foaming machine has an optimal interval value, the pressure is too large, the bubble wall is too thin, and the settlement distance is large. And the pressure is too small to produce foam, or the output of the foaming machine decreases. Different foaming machines have different optimal pressure ranges.

(3) Water control. Different water hardness has different effects on foam stability. Of course, some foaming agents are resistant to hard water and have little or no effect. But the impact of water cannot be ignored.

The quality of the foam changes with the pretreatment of the water. Some pretreatments will improve the stability of the foam and reduce the bleeding rate. Some pretreatment will increase the foam volume and foam multiple, but it is not conducive to the stability of the foam.

(4) Temperature control. Different temperatures have different effects on foam quality. Generally speaking, high temperature will increase the production of foam, but the foam wall becomes thinner and the foam stability is not good. At low temperature, it is not easy to foam, the water content of the foam increases, but the stability is better. In summer, the foaming machine should not be operated under the scorching sun, so as not to affect the foaming quality due to high temperature. In winter, it should be foamed under heating, or the foaming agent should be diluted with hot water to improve the foaming effect.

2. Making foam concrete slurry

This process mixes the foam with the cement slurry to form a foamed concrete slurry, which can finally be poured into the cavity of the wall.

(1) Mixing process. The mixing process includes batch mixing and continuous mixing. At present, all companies generally use continuous mixed bubbles. Although intermittent mixed bubbles have applications, they are rarely used. In the development of foam concrete, intermittent mixing is a widely used process. The process is to first produce foam and cement slurry, and then add the two into the blade foam mixer to mix into foam concrete slurry. This method is more suitable for product production, and is not suitable for on-site operation due to low efficiency.

(2) Continuous mixing is to send the foam and cement slurry into the static mixer at the same time, and the foam cement slurry is quickly carried out without power through the static mixing. Static mixers are commonly known as foam mixing tanks. It is a high-pressure steel cylinder with a diameter of 1000mm～2000mm. There is a static stirring piece in the middle.

(3) Quality control of mixed foam. The quality of the foam is mainly reflected in two aspects: the uniformity of the foam cement slurry, that is, the uniformity, and the density control of the foam cement slurry. The slurry should have a high degree of uniformity, its appearance is bright and smooth, it is elastic when pressed by hand, no foam floats, and there is no uneven mixing phenomenon visually.

The density of the slurry should meet the design requirements, the wet density difference should not exceed 5%, and there should be no fluctuations and instability. At present, a prominent problem of cast-in-place is density fluctuation. The reason for the unstable quality is that when you mix it, the amount of foam will fluctuate up and down. How do you control the density is a key issue.

(4) The main factors controlling the optimization of foam cement slurry:

a. Uniformity control factors. The controlling factor for the uniformity of foam cement slurry is mainly whether the design parameters of the static mixer are reasonable, especially its length, the number of internal mixing parts, the angle and the arrangement. These parameters have the best match. If the mix is unreasonable, the slurry will be uneven. Different manufacturers have different designs, and the core is whether they can achieve rationality and whether they have been tested and optimized before design.

b. Density control factors. The controlling factor of foam cement slurry density is the ratio of foam to cement slurry entering the static mixer, that is, whether the ratio of foam to cement slurry is reasonable and accurate. The larger the ratio, the lighter the cement slurry. If the ratio of the two is not well controlled, the density will fluctuate. The key is whether the equipment involves the installation of a foam and mud control mechanism, and the degree of automation of the mechanism. At present, some equipment is not equipped with a control mechanism, and the density is difficult to control.

Application of foam concrete

Lightweight concrete is widely used in energy-saving wall materials due to its good characteristics, and has also been used in other areas. Currently, lightweight coagulation

The application of soil in China is mainly cast-in-place roof insulation, lightweight wall panels, and compensation foundations. However, making full use of the good characteristics can continuously expand its application in construction engineering, speed up the project progress, and improve the quality of the project.

The price of foam concrete

The price of lightweight concrete varies randomly with production costs, transportation costs, international conditions, exchange rates, and the market supply and demand of lightweight concrete. Tanki New Materials Co. Ltd aims to help all industries and chemical wholesalers find high-quality products by providing a full range of products. If you are looking for lightweight concrete, please contact us for the latest price of lightweight concrete .

Supplier of foam concrete

As a global supplier of lightweight concrete, Tanki New Materials Co., Ltd. Has extensive experience in the performance, application and cost-effective manufacturing of advanced and engineering materials. The company has successfully developed a series of foam concrete additives (including lightweight concrete, CLC blocks provide concrete foaming agents, superplasticizers, foam concrete strength enhancers, etc.), high-purity targets, and functional materials. Ceramics and structural equipment, and provide OEM services.