In-situ polymerized modified precast foam for foamed concrete, its preparation method and application

Abstract

This invention discloses an in-situ polymerized modified precast foam for foamed concrete, its preparation method, and its application. The preparation method of the in-situ polymerized modified precast foam for foamed concrete includes the following steps: dissolving 1-3 parts by weight of a foaming agent in 100-150 parts by weight of water, then adding 0.2-0.5 parts by weight of methyl cellulose ether and 2-8 parts by weight of monomer, and after complete dissolution, adding 0.02-0.05 parts by weight of initiator and 0.01-0.03 parts by weight of crosslinking agent, and foaming under high-speed stirring to obtain the in-situ polymerized modified precast foam. The density of the precast foam obtained by this invention is 60-70 kg / m³. 3 The foam half-life is increased by 2-3 times. When the pre-formed foam of this invention is used to prepare foamed concrete, the 28-day flexural and compressive strength of the prepared foamed concrete is increased by 30-40%. This invention provides a new technology for the preparation of highly stable foams and high-performance foamed concrete.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to an in-situ polymerized modified precast foam for foamed concrete, its preparation method, and its application. Background Technology

[0002] Foamed concrete is a cement-based material containing numerous tiny closed pores. Due to its low density, sound absorption, noise reduction, and thermal insulation properties, foamed concrete has received widespread attention and application. However, because its porous structure significantly affects its strength and thermal insulation performance, foamed concrete also suffers from low compressive and flexural strength. Foam stability is one of the important factors influencing the performance of foamed concrete.

[0003] Foam is a thermodynamically unstable substance, easily broken by environmental influences. Research has found that using foam stabilizers can effectively improve the stability of foam, allowing it to remain stable for extended periods. Traditional foam stabilizers can be categorized by their mechanism of action as follows: 1. Those that enhance the interaction between surface-adsorbed molecules through synergistic effects; 2. Those that reduce the foam drainage rate by increasing the viscosity of the foaming agent, such as cellulose; 3. With the development of nanotechnology, nanoparticle foam stabilization technology is attracting increasing attention. Nanomaterials can be adsorbed onto the surface of bubbles over a large area, making the foam more stable.

[0004] In summary, while numerous studies have focused on improving the stability of foam to enhance the performance of foamed concrete, some shortcomings remain. Although these technologies can improve the compressive strength of foamed concrete, they do not significantly improve its toughness. Therefore, there is an urgent need to develop new technologies to address both the high stability of foam and the improvement of the toughness of foamed concrete. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method for preparing in-situ polymerized modified precast foam for foamed concrete. It utilizes in-situ polymerized foam stabilization technology to effectively improve the stability of foam, enabling the foam to exist stably for a long time, thereby improving the mechanical properties of foamed concrete and effectively solving the problems of poor foam stability and poor toughness of foamed concrete.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for preparing in-situ polymerized modified precast foam for foamed concrete includes the following steps:

[0008] Dissolve 1-3 parts by weight of foaming agent in 100-150 parts of water, then add 0.2-0.5 parts of methyl cellulose ether and 2-8 parts of monomer. After fully dissolving, add 0.02-0.05 parts of initiator and 0.01-0.03 parts of crosslinking agent, and foam under high-speed stirring to obtain in-situ polymerized modified pre-foam.

[0009] Optionally, the foaming agent is one of a protein foaming agent, a rosin resin foaming agent, and sodium dodecyl sulfate.

[0010] Optionally, the monomer is one of sodium acrylate and acrylamide.

[0011] Optionally, the initiator is composed of potassium persulfate and sodium bisulfite in a mass ratio of 2:1.

[0012] Optionally, the crosslinking agent is methylenebisacrylamide. To improve the adaptability and crosslinking effect of the crosslinking reaction in the material system of the present invention, and to ensure the stability and non-toxicity of the crosslinking process, the present invention preferably uses methylenebisacrylamide as the crosslinking agent, which can effectively improve the mechanical strength, flexibility, thermal stability, and chemical stability of the polymer.

[0013] Optionally, the stirring speed of the high-speed mixer is 800-1000 r / min.

[0014] Optionally, the density of the in-situ polymerized modified pre-fabricated foam is 60-70 kg / m³. 3 .

[0015] A second objective of the present invention is to provide an in-situ polymerized modified precast foam for foamed concrete, wherein the in-situ polymerized modified precast foam is prepared by the above-described method for preparing in-situ polymerized modified precast foam for foamed concrete.

[0016] A third objective of this invention is to provide an application of the above-mentioned in-situ polymerized modified precast foam in foamed concrete, the application comprising the following steps:

[0017] Calculate the amount of in-situ polymerized modified precast foam according to the design density of foamed concrete;

[0018] The weighed in-situ polymerized modified precast foam is added to the cement concrete slurry, stirred, molded, and cured to obtain foamed concrete.

[0019] The reaction mechanism of this invention:

[0020] This invention introduces monomeric external components during foam preparation, which adhere to the foam surface. Under the action of initiators and crosslinking agents, the monomers rapidly polymerize to form a viscous polymer macromolecular network that encapsulates the foam, increasing the viscosity of the foam liquid, reducing the foam drainage rate, and minimizing the merging of small bubbles into large bubbles, thus allowing the foam to remain stable for a long time. When foam is introduced into cement-based cementitious materials, the polymer on the foam surface can contact cement particles and crosslink with cement hydration products. The highly flexible polymer can improve the toughness of foamed concrete and enhance its performance.

[0021] Compared with existing technologies, the method for preparing in-situ polymerized modified precast foam for foamed concrete described in this invention has the following advantages:

[0022] 1. In the preparation process of the pre-formed foam of the present invention, the foaming agent and monomer are mixed in an aqueous solution. Under high-speed stirring, the foaming agent forms a large-volume foam. The sodium acrylate monomer has water-absorbing and hydrophobic groups, which can be adsorbed on the foam surface. Under the action of the initiator and crosslinking agent, a viscous macromolecular network film structure is formed around the bubbles, wherein the hydrophobic end faces the bubbles and the hydrophilic end faces the water. Therefore, the interfacial tension between the bubbles and the liquid is reduced, the presence of the bubbles is stabilized, and the half-life of the pre-formed foam is greatly improved. The density of the obtained pre-formed foam is 60-70 kg / m³. 3 The half-life of foam can be increased by 2-3 times.

[0023] 2. When the pre-made foam obtained by this invention is mixed with cement slurry, the polymer on the surface of the foam can interact with cement particles and hydration products to enhance the pore walls, thereby improving the compressive and flexural strength of the foam concrete. The 28-day flexural and compressive strength of the prepared foam concrete can be increased by 30-40%.

[0024] 3. The in-situ polymerization foam stabilization technology of this invention has a simple operation process and excellent foam stabilization effect, providing a new technology for the preparation of high-stability foam and high-performance foamed concrete. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions and effects of the present invention, several embodiments will be provided below. Obviously, the following description is only an embodiment and does not limit the scope of protection of the present invention.

[0026] The specific raw material formulations in the preparation methods of in-situ polymerized modified precast foam for foamed concrete in Examples 1 to 6 of this invention are shown in Table 1.

[0027] The specific preparation steps of the in-situ polymerized modified precast foam for foamed concrete in Examples 1-6 of this invention are as follows: First, dissolve sodium dodecyl sulfate foaming agent in water, then add methyl cellulose ether and sodium acrylate monomer and dissolve them completely. Then, add an initiator composed of potassium persulfate and sodium bisulfite in a mass ratio of 2:1 and a methylene bisacrylamide crosslinking agent, and stir at high speed at 800 r / min to foam the foam and obtain the in-situ polymerized modified precast foam.

[0028] The in-situ polymerized modified precast foam obtained in Examples 1-6 of this invention is used in the preparation of foamed concrete, specifically including the following steps:

[0029] 1) Preparation of cement concrete paste: Weigh an appropriate amount of silicate cement and water according to a water-cement ratio of 0.4, mix the silicate cement and water evenly to obtain cement concrete paste, wherein the silicate cement used is P·O42.5 ordinary silicate cement;

[0030] 2) Based on the design density of foamed concrete of 800 kg / m³ 3 Calculate the amount of in-situ polymerized modified pre-fabricated foam used;

[0031] 3) Weigh the in-situ polymerized modified precast foam according to the amount calculated in step 2), add it to the cement concrete slurry in step 1), stir, mold, and cure to obtain foamed concrete.

[0032] The performance of the in-situ polymerized modified precast foam prepared according to Examples 1-6 of this invention was tested in accordance with JGT 266-2011 "Foamed Concrete", and compared with the precast foam without modification by this invention (Comparative Example 1). The test results are shown in Table 1.

[0033] The performance of foamed concrete prepared by in-situ polymerized modified precast foam obtained by Examples 1-6 of this invention was tested in accordance with JGT 266-2011 "Foamed Concrete", and compared with foamed concrete prepared by precast foam without the modification of this invention (Comparative Example 1). The test results are shown in Table 2.

[0034] As can be seen from the results in Tables 1 and 2, the in-situ polymerization foam stabilization technology of this invention can significantly improve the stability of foam, and the half-life of the obtained precast foam can be increased by 2-3 times; the flexural and compressive strength of foamed concrete prepared using the obtained precast foam can be increased by 30-40%.

[0035] Table 1

[0036]

[0037] Table 2

[0038]

[0039] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing in-situ polymerized modified precast foam for foamed concrete, characterized in that, Includes the following steps: Dissolve 1-3 parts of foaming agent in 100-150 parts of water by weight, then add 0.2-0.5 parts of methyl cellulose ether and 2-8 parts of monomer. After fully dissolving, add 0.02-0.05 parts of initiator and 0.01-0.03 parts of crosslinking agent, and foam under high-speed stirring to obtain in-situ polymerized modified pre-foam. The foaming agent is one of protein foaming agent, rosin resin foaming agent, and sodium dodecyl sulfate; The monomer is one of sodium acrylate and acrylamide; The initiator is composed of potassium persulfate and sodium bisulfite in a mass ratio of 2:1; The crosslinking agent is methylenebisacrylamide; The stirring speed of the high-speed mixer is 800-1000 r / min.

2. The method for preparing in-situ polymerized modified precast foam for foamed concrete according to claim 1, characterized in that, The density of the in-situ polymerized modified pre-fabricated foam is 60-70 kg / m³. 3 .

3. An in-situ polymerized modified precast foam for foamed concrete, characterized in that, It is prepared by the method for preparing in-situ polymerized modified precast foam for foamed concrete as described in any one of claims 1-2.

4. The application of the in-situ polymerized modified precast foam according to claim 3 in foamed concrete, characterized in that, Includes the following steps: Calculate the amount of in-situ polymerized modified precast foam according to the design density of foamed concrete; The weighed in-situ polymerized modified precast foam is added to the cement concrete slurry, stirred, molded, and cured to obtain foamed concrete.

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