Ultralow-density high-steady-state foam based on pressure regulation-gradient foaming process and preparation method thereof

Abstract

The invention discloses ultralow-density high-steady-state foam based on a pressure regulation-gradient foaming process and a preparation method of the ultralow-density high-steady-state foam. The ultralow-density high-steady-state foam is prepared from the following raw materials in parts by mass: 0.5-0.7 part of a surfactant, 0.3-0.6 part of a thickening agent, 3-5 parts of a nano foaming agent, 2.3-5.1 parts of a nano foam stabilizer, 0.03-0.05 part of dilute sulphuric acid and 90-93 parts of water, the sum of the proportions of all the components is 100, and the ultralow-density high-steady-state foam is prepared by adopting a pressure regulation-gradient foaming process. The density of the ultralow-density high-steady-state foam is 15-25g / L, and compared with common foam, the 5h bleeding rate is reduced by 10-20%, and the average pore size of the foam is reduced by 15-20%; according to the prepared ultra-low-density high-steady-state foam, the density of prefabricated foam is greatly reduced, the stability of the prefabricated foam is improved, and a new technology is provided for preparing high-performance ultra-light high-strength foam concrete.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal insulation materials, and specifically relates to an ultra-low density high-steady-state foam based on a pressure regulation-gradient foaming process and a preparation method thereof. Background Art

[0002] As a typical cement-based porous material, foamed concrete is usually prepared by adding prefabricated foam to the cementitious material paste in a stirring manner. By controlling the amount of prefabricated foam used, foamed concrete of different density levels can be prepared. Since lightweight and porous foamed concrete has the advantages of good thermal insulation, energy absorption and buffering, and self-leveling, it is widely used as a non-structural and semi-structural material in infrastructure construction. However, the disadvantages of foamed concrete are also obvious, including low compressive strength and poor stability. Moreover, the lighter the density of the foamed concrete, the lower its compressive strength and the worse its stability.

[0003] The low stability of prefabricated foam is the main reason for the instability of foam concrete paste. Before the cementitious material paste solidifies, the foam cannot support the skeleton of the foam concrete, causing the foam concrete to collapse. The pore size distribution of hardened foam concrete is closely related to the compressive strength, and uneven distribution of bubbles will also lead to low compressive strength. High-stability foam can inhibit liquid film rupture and foam coarsening, and can improve the pore size distribution of bubbles in hardened foam concrete.

[0004] Therefore, improving the stability of prefabricated foam to improve the compressive strength and stability of foam concrete is an important technical means to prepare lightweight foam concrete with high stability and high strength. Summary of the invention

[0005] The present invention aims to provide a method for preparing ultra-low-density high-stable foam based on a pressure regulation-gradient foaming process. The bulk density of the prepared ultra-low-density high-stable foam is greatly reduced compared with general foam, and the foam stability is better, so as to improve the compressive strength and stability of foam concrete.

[0006] To achieve the above object, the technical solution of the present invention is implemented as follows: a method for preparing ultra-low density high-stable foam based on pressure regulation-gradient foaming process, wherein the raw material composition and mass fraction of the ultra-low density high-stable foam are: 0.5-0.7 parts of surfactant, 0.3-0.6 parts of thickener, 3-5 parts of nano gasifier, 2.3-5.1 parts of nano foam stabilizer, 0.03-0.05 parts of dilute sulfuric acid, 90-93 parts of water, and the sum of the proportions of each component is 100;

[0007] The preparation method comprises:

[0008] Step 1), uniformly mixing the said portion of thickener with 40-45 portions of water, and pre-stirring; then uniformly mixing the said portion of nano-gassing agent and nano-foam stabilizer with the remaining water, and adding them to the thickener solution after ultrasonic dispersion and continuing to stir, finally obtaining solution A;

[0009] Step 2), placing the obtained solution A in a sealed pressurizable container, adding the surfactant and dilute sulfuric acid in the aforementioned number, applying a pressure of 105-150 kPa to the pressurizable container, and stirring the obtained mixed solution at high speed using a mesh stirring blade; finally, opening the valve of the pressurizable container, allowing the internal foam to expand uniformly under normal pressure, and allowing the foam to stand to obtain an ultra-low density high-steady-state foam based on a pressure regulation-gradient foaming process.

[0010] The mechanism of the preparation method of the present invention is as follows: the density of the foam is greatly reduced by the pressure regulation-gradient foaming process to achieve ultra-low density. In the process of high pressure recovery to normal pressure, the pressurized bubbles are uniformly expanded, effectively reducing the average pore size of the foam and achieving high stability. The foam with a larger average pore size is prepared by pressure environment regulation, and the nano-gasifier plays a role of nano-foam stabilization. At the same time, the pH value of the foaming liquid is adjusted by chemical means to induce the nano-gasifier to release foam with a smaller pore size, complete gradient foaming, and further optimize the pore size distribution of the foam.

[0011] Furthermore, in step 1), the stirring time during pre-stirring is 2-3 h, the stirring rate is 300-400 rpm, the ultrasonic dispersion time is 4-6 min, and the stirring time during continued stirring is 1-2 h, the stirring rate is 150-200 rpm.

[0012] Furthermore, in step 2), when the mixed solution is stirred at high speed, the stirring time is 3-5 min, the stirring rate is 700-900 rpm, and the standing time is 5-10 min.

[0013] Furthermore, the surfactant is a mixture of cocamidopropyl betaine and ammonium lauryl sulfate, wherein the mass ratio of the two is cocamidopropyl betaine:ammonium lauryl sulfate=2:1.

[0014] Furthermore, the thickener is a mixture of one or more of xanthan gum, weinensis gum and polyacrylamide.

[0015] Furthermore, the nano gas generating agent is nano calcium carbonate, the median particle size of which is 100-300 nm.

[0016] Furthermore, the nano foam stabilizer is nano silicon dioxide, which has a hydrophilic chemical property and a median particle size of 100-300 nm.

[0017] Furthermore, the pore size of the screen-type stirring blade is 60-90 μm.

[0018] Furthermore, the pH of the solution is adjusted to 2-3 by using dilute sulfuric acid, and the concentration of the dilute sulfuric acid is 0.05-0.3 mol / L.

[0019] The present invention also provides an ultra-low density high-stable foam based on a pressure regulation-gradient foaming process, which is prepared by the above-mentioned preparation method. The foam density of the ultra-low density high-stable foam is 15-25 g / L.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides an ultra-low density high-stable foam based on a pressure regulation-gradient foaming process, the foam density reaches 15-25g / L, and compared with ordinary foam, the 5h water bleeding rate is reduced by 10-20%, and the average pore size of the foam is reduced by 15-20%. The ultra-low density high-stable foam prepared by the present invention greatly reduces the density of the prefabricated foam and improves its stability, can improve the compressive strength and stability of the foam concrete, and provides a new technology for preparing high-performance ultra-lightweight high-strength foam concrete. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions and technical effects of the present invention, several embodiments are provided below. Obviously, what is described below is only an embodiment and does not limit the protection scope of the present invention.

[0023] The ultra-low density and high stable state foam of Examples 1 to 10 is prepared by using the following components using a pressure regulation-gradient foaming process: 0.5-0.7 parts of a surfactant, 0.3-0.6 parts of a thickener, 3-5 parts of a nano-gassing agent, 2.3-5.1 parts of a nano-foam stabilizer, 0.1 mol / L dilute sulfuric acid 0.03-0.05 parts, and 90-93 parts of water, and the sum of the proportions of each component is 100.

[0024] The thickener is xanthan gum, the median particle size of the nano gas generating agent is 200 nm, the median particle size of the nano foam stabilizer is 200 nm, and the aperture of the mesh stirring blade is 70 μm.

[0025] The ultra-low density high stable foam is prepared by the following specific steps:

[0026] (1) The thickener of the above number is mixed with 40-43 parts of water, and stirred in advance for 2 hours at a stirring rate of 300 rpm. Then the nano-gas generating agent and nano-foam stabilizer of the above number are mixed with the remaining water, and ultrasonically dispersed for 5 minutes, and then added to the thickener solution and stirred for 2 hours at a stirring rate of 200 rpm to finally obtain solution A.

[0027] (2) The obtained solution A is placed in a closed pressurizable container, and then the surfactant and 0.1 mol / L dilute sulfuric acid are added, the pH of the solution is adjusted to 2-3, and an air pump is used to apply a pressure of 105-150 kPa to the pressurizable container. At the same time, the mixed solution is stirred at high speed using a mesh stirring blade, the stirring time is 5 minutes, and the stirring rate is 900 rpm. Finally, the valve of the pressurizable container is opened, and the internal foam is uniformly expanded under normal pressure and left to stand for 10 minutes, thereby obtaining an ultra-low density high-steady-state foam based on a pressure regulation-gradient foaming process, and the specific material ratio is shown in Table 1.

[0028] Table 1 Material ratio table

[0029]

[0030]

[0031] The difference between Comparative Example 1 and Examples 1-10 is that the pressurizable container in step (2) is not pressurized. The difference between Comparative Example 2 and Examples 1-10 is that no nano foam stabilizer is added in step (1). The difference between Comparative Example 3 and Examples 1-10 is that no nano gas generating agent is added in step (1).

[0032] The foam density, foam water exudation rate and foam average pore diameter of the foams prepared in Examples 1 to 10 and Comparative Examples 1 to 3 were tested. The test results are shown in Table 2.

[0033] Table 2 Foam performance test table

[0034]

[0035] It can be seen from the foam performance data in Table 2 that the ultra-low density high-steady-state foam based on the pressure regulation-gradient foaming process has a foam density of 15-25 g / L. Compared with the control example, the water bleeding rate in 5 hours is reduced by 10-20%, and the average pore size of the foam is reduced by 15-20%.

[0036] The above are only 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 in the protection scope of the present invention.

Claims

1. A method for preparing ultra-low density high-steady-state foam based on pressure regulation-gradient foaming process, characterized in that: The raw material composition and mass fraction of the ultra-low density high-stable foam are: 0.5-0.7 parts of surfactant, 0.3-0.6 parts of thickener, 3-5 parts of nano gasifier, 2.3-5.1 parts of nano foam stabilizer, 0.03-0.05 parts of dilute sulfuric acid, 90-93 parts of water, and the sum of the proportions of each component is 100; The preparation method comprises: Step 1), uniformly mix the thickener in the above number with 40-45 parts of water, and stir in advance; Then, the nano-gassing agent and the nano-foam stabilizer are mixed evenly with the remaining water, and after ultrasonic dispersion, added into the thickener solution and stirred continuously to finally obtain solution A; Step 2), placing the obtained solution A in a sealed pressurizable container, adding the surfactant and dilute sulfuric acid in the aforementioned number, applying a pressure of 105-150 kPa to the pressurizable container, and stirring the obtained mixed solution at high speed using a mesh stirring blade; finally, opening the valve of the pressurizable container, allowing the internal foam to expand uniformly under normal pressure, and allowing the foam to stand to obtain an ultra-low density high-steady-state foam based on a pressure regulation-gradient foaming process.

2. The preparation method according to claim 1, characterized in that: In step 1), the stirring time during pre-stirring is 2-3 hours, the stirring rate is 300-400 rpm, the ultrasonic dispersion time is 4-6 minutes, and the stirring time during continued stirring is 1-2 hours, the stirring rate is 150-200 rpm.

3. The preparation method according to claim 1, characterized in that: In step 2), when the mixed solution is stirred at high speed, the stirring time is 3-5 minutes, the stirring rate is 700-900 rpm, and the standing time is 5-10 minutes.

4. The preparation method according to claim 1, characterized in that: The surfactant is a mixture of cocamidopropyl betaine and ammonium lauryl sulfate, wherein the mass ratio of the two is cocamidopropyl betaine:ammonium lauryl sulfate=2:

1.

5. The preparation method according to claim 1, characterized in that: The thickener is a mixture of one or more of xanthan gum, weinensis gum and polyacrylamide.

6. The preparation method according to claim 1, characterized in that: The nano gas generating agent is nano calcium carbonate, and the median particle size thereof is 100-300nm.

7. The preparation method according to claim 1, characterized in that: The nano foam stabilizer is nano silicon dioxide, which has hydrophilic chemical properties and a median particle size of 100-300nm.

8. The preparation method according to claim 1, characterized in that: The aperture of the mesh stirring blade is 60-90 μm.

9. The preparation method according to claim 1, characterized in that: The pH of the solution was adjusted to 2-3 by using dilute sulfuric acid, and the concentration of the dilute sulfuric acid was 0.05-0.3 mol / L.

10. An ultra-low density high-stable foam based on a pressure-controlled gradient foaming process, which is prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The foam density of the ultra-low density high-stable foam is 15-25 g / L.

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