A foamed cement additive and a method of making the same

Abstract

The application relates to the field of cement additives, in particular to a foamed cement additive and a preparation method thereof, wherein the foamed cement additive comprises the following raw materials in parts by weight: an animal protein foaming agent 35-45 parts, modified gelatin 3-5 parts and a surfactant 1-3 parts. The foamed cement additive prepared by the application has the characteristics of high foaming ratio, fine and uniform foam and good stability.

Description

Technical Field

[0001] This invention relates to the field of cement additives, and more specifically to a foamed cement additive and its preparation method. Background Technology

[0002] Foamed cement is a lightweight, heat-insulating, and sound-insulating energy-saving material widely used in the construction industry. Commonly used cement foaming agents can be divided into rosin resin-based foaming agents, surfactant-based foaming agents, protein-based foaming agents, and hydrogen peroxide-based foaming agents. Among them, rosin resin-based foaming agents have poor foaming ability, poor foam stability, and low foaming ratio; surfactant-based foaming agents foam quickly and produce a large amount of foam, but the foam stability is poor and it is not easily degraded, posing environmental pollution problems; hydrogen peroxide-based foaming agents produce a large amount of foam, but the foaming rate is difficult to control, and problems such as large bubbles and uneven foaming are prone to occur; although protein-based foaming agents have the advantages of wide availability, easy degradation, and no environmental pollution, their foaming ratio is relatively low. Therefore, how to overcome the problems of protein-based foaming agents through technological improvement and innovation has gradually attracted attention.

[0003] Patent CN104725070B discloses a hair-based cement foaming agent. The process involves pretreating the agent with water, hair, and sodium bisulfite in a constant-temperature water bath at 80-95℃ for 1-2 hours, filtering, and then adding water and alkali to the resulting solid for hydrolysis at 80-95℃ for 5-7 hours to obtain an animal protein-based cement foaming agent base liquid. Foam-stabilizing components such as gum arabic powder, triethanolamine, gelatin, dodecyl alcohol, polyvinyl alcohol, carboxymethyl cellulose, and hydroxyethyl methyl cellulose, as well as reinforcing components such as sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, and sodium dodecyl ether sulfate are added to the base liquid and mixed uniformly to obtain the animal protein-based cement foaming agent. The resulting foaming agent produces fine, uniform foam with high stability. However, the foam-stabilizing components used still have certain defects; for example, the low degree of cross-linking of the gelatin results in low strength and thickening properties, leading to poor foam stabilization.

[0004] Patent CN105948650B discloses a protein-based cement foaming agent and a method for preparing concrete containing the foaming agent. The method involves hydrolyzing chromium-containing leather scraps to obtain a leather scrap hydrolysate. This hydrolysate is then compounded with a foaming component and a foam-stabilizing component such as carboxymethyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl starch, soluble starch, cationic starch, polyacrylamide, sodium acrylate, sodium alginate, polyvinyl alcohol, polyethylene oxide, and methyl cellulose ether to obtain the protein-based foaming agent. The resulting protein-based foaming agent exhibits high foam stability, fine foam, and uniform bubble distribution. However, the foam-stabilizing components used, such as carboxymethyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl cellulose, and carboxymethyl starch, are unstable in cement due to pH fluctuations, resulting in poor foam stabilization.

[0005] Therefore, there is an urgent need in the market for a foaming cement additive with good foam stability. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to obtain a foamed cement additive with high foaming ratio, fine and uniform foam, and good stability.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a foamed cement additive, which, by weight, comprises the following raw materials: 35-45 parts of animal protein foaming agent, 3-5 parts of modified gelatin, and 1-3 parts of surfactant.

[0009] The foamed cement additive prepared by this application using animal protein foaming agent as foaming agent, modified gelatin as stabilizing component, and adding surfactant has the advantages of high foaming ratio and good foam stability.

[0010] In some embodiments, the surfactant is one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, and sodium dodecyl alcohol polyoxyethylene ether sulfate.

[0011] Preferably, the surfactant is sodium dodecyl alcohol polyoxyethylene ether sulfate.

[0012] Sodium dodecyl polyoxyethylene sulfate has strong hydrogen bonding with the amine groups on modified gelatin and modified silica, which helps to improve the stability of the system and thus the stability of the foam.

[0013] In some embodiments, the method for preparing the modified gelatin includes the following steps: adding gelatin to deionized water, stirring at 30-40°C for 10-20 min, adding 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 89-95wt% concentrated sulfuric acid, heating to 50-60°C and reacting for 1-2 h, washing and drying to obtain the modified gelatin.

[0014] In existing technologies, biodegradable gelatin is often used as a foam stabilizer in combination with animal protein foaming agents. However, during cement foaming, the low viscosity and strength of gelatin reduce its foam stabilizing performance. This application found that modifying gelatin with 1,2,4,5-cyclohexanetetracarboxylic dianhydride can improve foam stability. This may be because, on the one hand, 1,2,4,5-cyclohexanetetracarboxylic dianhydride contains two anhydride groups, which can react with the amino groups in gelatin to achieve cross-linking, thereby improving the mechanical properties and viscosity of gelatin and forming a protective film on the foam surface, which is beneficial to improving the stability and strength of the foam. On the other hand, the modified gelatin contains multiple cyclic structures, which can further improve the strength and viscosity of gelatin. Furthermore, the introduction of cyclohexyl groups increases the steric hindrance between gelatin segments, which can prevent collisions and dissolution between foams, further improving the stability of the foam.

[0015] In some embodiments, the mass ratio of the gelatin to deionized water is 1:(2-4).

[0016] In some embodiments, the mass ratio of the gelatin to 1,2,4,5-cyclohexanetetracarboxylic dianhydride is 1:(0.4-0.7).

[0017] This application can further improve the foam stability of foamed cement additives by limiting the mass ratio of gelatin and deionized water, as well as the mass ratio of gelatin and 1,2,4,5-cyclohexanetetracarboxylic dianhydride. This may be because at this mass ratio, 1,2,4,5-cyclohexanetetracarboxylic dianhydride is more likely to undergo hydrolysis to form carboxylic acid groups that react with the amino groups on the gelatin. Furthermore, the residual anhydride groups on the modified gelatin can adjust the pH of the system, which is beneficial to improving the foaming rate and foam stability of the protein foaming agent.

[0018] In some embodiments, the foamed cement additive further comprises 1-3 parts by weight of modified silica.

[0019] In some embodiments, the method for preparing the modified silica includes the following steps: adding silica and A-1120 silane coupling agent to 89-95 wt% ethanol and stirring at room temperature for 20-30 min, and then drying to obtain modified silica.

[0020] This application demonstrates that adding modified silica to foamed cement additives can further enhance foam stability. This is likely because the hydroxyl groups on the surface of the modified silica particles are replaced, giving the particle surface a certain degree of hydrophobicity. This allows for better adsorption between the foam gas-liquid interface film, reducing disproportionation between foam particles, extending the foam's drainage half-life, and thus improving the foaming ratio and foam stability. Furthermore, this application preferentially uses A-1120 silane coupling agent as a silica modifier, which can increase the amine group content on the modified silica, enabling it to react with residual anhydride groups on the modified gelatin. This further enhances the dispersibility of silica and its adsorption between the foam gas-liquid interface film, thereby improving foam stability.

[0021] In some embodiments, the silicon dioxide has a particle size of 10-50 nm.

[0022] In some embodiments, the mass ratio of the silica to the A-1120 silane coupling agent is 1:(0.15-0.25).

[0023] This application can further improve the ratio of silica to A-1120 silane coupling agent by limiting the mass ratio. This may be because the reaction of the anhydride group with the amine group may increase the pH of the system and reduce the foaming rate of the protein foaming agent.

[0024] Another aspect of the present invention provides a method for preparing a foamed cement additive, comprising the following steps: adding a surfactant, modified silica, and modified gelatin to an animal protein foaming agent and stirring at 20-30°C for 5-15 minutes, and letting it stand at room temperature for 5-10 days to obtain the foamed cement additive.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The foamed cement additive prepared by the present invention by selecting animal protein foaming agent as foaming agent, modified gelatin as stabilizing component, and adding surfactant has the advantages of high foaming ratio and good foam stability.

[0027] (2) The present invention uses 1,2,4,5-cyclohexanetetracarboxylic dianhydride to modify gelatin to achieve cross-linking, thereby improving the viscosity and mechanical properties of gelatin, which is beneficial to improving the foam expansion ratio, stability and strength. On the other hand, the modified gelatin contains multiple cyclic structures, which can further improve the viscosity and strength of gelatin. Furthermore, the introduction of cyclohexyl groups increases the steric hindrance between gelatin chain segments, which can prevent collision and dissolution between foams, and further improve the stability of foam.

[0028] (3) The preferred silane coupling agent of the present invention, A-1120, can be used as a modifier for silica to increase the amine content on the modified silica, so that it can react with the residual anhydride groups on the modified gelatin, thereby further improving the dispersibility of silica and its adsorption between the foam gas-liquid interface film. Detailed Implementation

[0029] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0030] In the following examples and comparative examples, except for modified gelatin and modified silica, all other compounds and related reagents used were commercially available. The animal protein foaming agent, model FP30, was purchased from Chiping Zetai Building Materials Co., Ltd.; the gelatin was purchased from Sichuan Huanxu Biotechnology Co., Ltd.; the silica, with an average particle size of 30 nm, was purchased from Beijing Deco Island Gold Technology Co., Ltd.; and sodium dodecyl alcohol polyoxyethylene ether sulfate was purchased from Jinan Huijinchuan Trading Co., Ltd.

[0031] Preparation Example 1

[0032] The preparation method of modified gelatin-1 includes the following steps: 10g of gelatin is added to 30g of deionized water, stirred at 35℃ for 15min, 5.5g of 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 1g of 92wt% concentrated sulfuric acid are added, the temperature is raised to 55℃ and reacted for 1.5h, and the mixture is washed and dried to obtain modified gelatin-1.

[0033] Preparation Example 2

[0034] The preparation method of modified gelatin-2 is the same as that in preparation example 1, except that the amount of deionized water added is 50g.

[0035] Preparation Example 3

[0036] The preparation method of modified gelatin-3 is the same as that in preparation example 1, except that the amount of 1,2,4,5-cyclohexanetetracarboxylic dianhydride added is 2g.

[0037] Preparation Example 4

[0038] The preparation method of modified silica-1 includes the following steps: 10g of silica and 2g of A-1120 silane coupling agent are added to 30g of 92wt% ethanol and stirred at room temperature for 25min. After drying, modified silica-1 is obtained.

[0039] Preparation Example 5

[0040] The specific implementation method for preparing modified silica-2 is the same as in preparation example 4, except that the amount of A-1120 silane coupling agent added is 4g.

[0041] Example 1

[0042] A foamed cement additive, by weight, comprises the following raw materials: 40 parts animal protein foaming agent, 4 parts modified gelatin-1, and 2 parts sodium dodecyl alcohol polyoxyethylene ether sulfate.

[0043] The preparation method of the foamed cement additive in this embodiment includes the following steps: sodium dodecyl polyoxyethylene ether sulfate and modified gelatin-1 are added to an animal protein foaming agent and stirred at 25°C for 10 minutes, and then left to stand at room temperature for 7 days to obtain the foamed cement additive.

[0044] Example 2

[0045] A foamed cement additive, by weight, comprises the following raw materials: 35 parts animal protein foaming agent, 3 parts modified gelatin-1, and 1 part sodium dodecyl alcohol polyoxyethylene ether sulfate.

[0046] The preparation method of foamed cement additive in this embodiment includes the following steps: sodium dodecyl polyoxyethylene ether sulfate and modified gelatin-1 are added to an animal protein foaming agent and stirred at 20°C for 15 minutes, and then left to stand at room temperature for 5 days to obtain the foamed cement additive.

[0047] Example 3

[0048] A foamed cement additive, by weight, comprises the following raw materials: 45 parts animal protein foaming agent, 5 parts modified gelatin-1, and 3 parts sodium dodecyl alcohol polyoxyethylene ether sulfate.

[0049] The preparation method of foamed cement additive in this embodiment includes the following steps: sodium dodecyl polyoxyethylene ether sulfate and modified gelatin-1 are added to animal protein foaming agent and stirred at 30°C for 5 minutes, and then left to stand at room temperature for 10 days to obtain foamed cement additive.

[0050] Example 4

[0051] A foamed cement additive and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified gelatin-1 is replaced with modified gelatin-2 in an equal amount.

[0052] Example 5

[0053] A foamed cement additive and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified gelatin-1 is replaced with modified gelatin-3 in an equal amount.

[0054] Example 6

[0055] A foamed cement additive, by weight, comprises the following raw materials: 40 parts animal protein foaming agent, 4 parts modified gelatin-1, 2 parts modified silica-1, and 2 parts sodium dodecyl alcohol polyoxyethylene ether sulfate.

[0056] The preparation method of the foamed cement additive in this embodiment includes the following steps: sodium dodecyl polyoxyethylene ether sulfate, modified gelatin-1, and modified silica-1 are added to an animal protein foaming agent and stirred at 25°C for 10 minutes, and then left to stand at room temperature for 7 days to obtain the foamed cement additive.

[0057] Example 7

[0058] A foamed cement additive and its preparation method are described. The specific implementation method is the same as that in Example 6, except that modified silica-1 is replaced with modified silica-2 in an equal amount.

[0059] Example 8

[0060] A foamed cement additive and its preparation method are described. The specific implementation method is the same as in Example 6, except that modified silica-1 is replaced with an equal amount of silica.

[0061] Comparative Example 1

[0062] A foaming cement additive and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified gelatin-1 is replaced with gelatin in an equal amount.

[0063] Performance testing

[0064] The foamed cement additives obtained in the above embodiments and comparative examples were tested for the following properties:

[0065] (1) Foaming height, half-life, and foam stabilization time: 100g of each foaming cement additive and 50g of water were placed in a 1000ml tall beaker marked with volume. The beaker was stirred at 3000r / min for 1min to induce foaming, and the foaming height and foam volume were measured. The time when the foaming liquid height decreased to half of the initial foam volume was recorded as the half-life. When the foam volume was 100ml remaining, the foam was considered to have disappeared, and the foam stabilization time was recorded.

[0066] (2) Method for determining foam sinking distance: Take a container (250ml beaker) with an inner diameter of 6cm and a height of 9cm, fill it with the newly generated foam, smooth the surface, cover the foam with a piece of paper, place it in a calm and windless place, and measure the foam sinking distance after 40 minutes.

[0067] The test results are shown in Table 1:

[0068] Table 1

[0069] Group Bubble height / mm Steeping time / h Half-life / h Settlement distance / mm Example 1 55 72.2 32.7 1 Example 2 53 71.5 32.3 1 Example 3 52 69.3 31.8 1 Example 4 54 63.6 22.9 2 Example 5 52 62.4 23.1 2 Example 6 57 74.9 35.6 1 Example 7 55 71.1 34.5 1 Example 8 51 54.8 19.2 2 Comparative Example 1 55 42.7 15.1 2

[0070] As shown in Table 1, the foaming cement additives in Examples 1-3 of this invention have high foaming ratios and good foam stability. A comparison of Examples 4, 5, and 1 shows that changing the ratio of gelatin to deionized water or gelatin to 1,2,4,5-cyclohexanetetracarboxylic dianhydride affects the grafting rate of 1,2,4,5-cyclohexanetetracarboxylic dianhydride onto gelatin and the pH of the system, leading to a decrease in the foam stability of the protein foaming agent. A comparison of Examples 6 and 1 shows that adding modified silica further improves the foam stabilizing performance of the foaming cement additive. A comparison of Examples 7 and 1 shows that changing the ratio of silica to A-1120 silane coupling agent affects the pH of the system, leading to a decrease in the foam stability of the protein foaming agent. A comparison of Examples 8 and 1 shows that without modified silica, the foam stabilizing performance of the foaming cement additive decreases. A comparison of Comparative Example 1 and Example 1 shows that using unmodified gelatin as a foam stabilizing component results in poor foam stabilizing performance of the foaming cement additive.

[0071] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A foamed cement additive, characterized in that, The foamed cement additive comprises the following raw materials in parts by weight: 35-45 parts of animal protein foaming agent, 3-5 parts of modified gelatin, and 1-3 parts of surfactant. The preparation method of the modified gelatin comprises the following steps: adding gelatin into deionized water, stirring at 30-40 DEG C for 10-20 min, adding 1,2,4,5-cyclohexane tetracarboxylic dianhydride and 89-95 wt% concentrated sulfuric acid, heating to 50-60 DEG C for 1-2 h, washing and drying to obtain the modified gelatin.

2. The foamed cement additive of claim 1, wherein, The surfactant is one or more of sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate and sodium dodecanol polyoxyethylene ether sulfate.

3. The foamed cement additive of claim 1, wherein, The mass ratio of the gelatin to the deionized water is 1:(2-4).

4. The foamed cement additive of claim 1, wherein, The mass ratio of the gelatin to 1,2,4,5-cyclohexane tetracarboxylic dianhydride is 1:(0.4-0.7).

5. The foamed cement additive of claim 1, wherein, The foamed cement additive further comprises 1-3 parts by weight of modified silicon dioxide.

6. The foamed cement additive of claim 5, wherein, The preparation method of the modified silicon dioxide comprises the following steps: adding silicon dioxide and A-1120 silane coupling agent into 89-95 wt% ethanol, stirring at room temperature for 20-30 min, and drying to obtain the modified silicon dioxide.

7. The foamed cement additive of claim 6, wherein, The particle size of the silicon dioxide is 10-50 nm.

8. The foamed cement additive of claim 6, wherein, The mass ratio of the silicon dioxide to the A-1120 silane coupling agent is 1:(0.15-0.25).

9. A method of producing a foamed cement additive according to any one of claims 5 to 8, characterised in that, The preparation method of the foamed cement additive comprises the following steps: adding the surfactant, the modified silicon dioxide and the modified gelatin into the animal protein foaming agent, stirring at 20-30 DEG C for 5-15 min, and standing at room temperature for 5-10 days.