Self-repairing waterproof material and preparation method thereof

Abstract

The application relates to the technical field of building materials, and discloses a self-repairing waterproof material and a preparation method thereof. The self-repairing waterproof material comprises the following raw materials in parts by mass: 20-40 parts of Portland cement, 10-20 parts of diatomite, 10-20 parts of modified bentonite, 5-15 parts of active ingredients, 1-5 parts of lubricant and 1-5 parts of water reducing agent. The self-repairing waterproof material provided by the application has good waterproof performance, the 28-day impermeable pressure can reach 2.83 MPa, and the 56-day secondary impermeable pressure can reach 1.65 MPa; moreover, the self-repairing waterproof material prepared by the application has excellent self-repairing performance and can self-repair cracks below 2.5 mm, which is far superior to the existing self-repairing putty.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and more specifically, to a self-healing waterproof material and its preparation method. Background Technology

[0002] Putty, an essential building material before painting, primarily functions to smooth wall surfaces, eliminating unevenness and providing a smooth base for subsequent paint application. However, during the curing process, environmental factors such as excessively high or low temperatures, humidity levels, and high airflow can cause putty to crack. This cracking not only affects the aesthetics of the wall but can also compromise its stability. Therefore, developing a putty that can inhibit cracking and achieve self-healing of cracks has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0003] The purpose of this invention is to provide a self-healing waterproof material, which is a putty that can inhibit cracking and achieve self-repair of cracks, and has good self-healing and waterproof properties.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] One of the technical solutions of this invention:

[0006] A self-healing waterproof material comprises the following raw materials in parts by weight: 20-40 parts silicate cement, 10-20 parts diatomaceous earth, 10-20 parts modified bentonite, 5-15 parts active ingredient, 1-5 parts lubricant, and 1-5 parts water-reducing agent.

[0007] As a preferred embodiment, a self-healing waterproof material comprises the following raw materials in parts by weight: 30 parts silicate cement, 15 parts diatomaceous earth, 15 parts modified bentonite, 10 parts active ingredient, 3 parts lubricant, and 3 parts water-reducing agent.

[0008] This invention adds diatomaceous earth to putty, which can improve the self-healing properties of the putty. Analysis shows that diatomaceous earth can absorb and release moisture from the environment, regulating the moisture content of the putty. When cracks exist in the putty, diatomaceous earth can absorb some moisture from the atmosphere, creating an environment conducive to the formation of calcium ions and silicate ions, thereby promoting the formation of calcium silicate gel and achieving self-repair of the putty. Moreover, the water absorption properties of diatomaceous earth can also help improve the waterproof properties of the putty.

[0009] Furthermore, the modified bentonite is prepared by calcining the bentonite.

[0010] Furthermore, the calcination treatment is carried out at a temperature of 800–900°C for a time of 20–40 minutes;

[0011] Preferably, the calcination temperature is 850℃ and the time is 30min.

[0012] This invention uses calcined and modified bentonite as raw material, which can effectively enhance the waterproof and self-healing properties of putty. Analysis shows that bentonite is a natural porous clay mineral with hygroscopic and swelling properties, capable of absorbing 8-15 times its own volume of water, with an expansion rate of 250%-1000%. Directly applying it to building materials such as putty will lead to problems such as putty layer cracking and reduced waterproof performance due to its excessively high hygroscopic and swelling rate. Therefore, if it is to be used in building materials such as putty, it needs to be modified to reduce its hygroscopic and swelling rate. This invention uses high-temperature calcination to modify bentonite, achieving high... During the calcination process, the microporous structure of bentonite is damaged, reducing the number of micropores. Since micropores are important for moisture adsorption, the reduction in the number of micropores directly leads to a decrease in bentonite's ability to adsorb moisture, thereby reducing its hygroscopic swelling rate. Moreover, while reducing the microporous structure, high-temperature calcination also increases the density of bentonite, which can directly reduce its hygroscopic swelling rate. In addition, prolonged high-temperature calcination can also break some of the chemical bonds of hydrophilic groups on the surface of bentonite. By breaking these chemical bonds, the hydrophilicity of bentonite can be reduced, thereby reducing its ability to adsorb water and further reducing its hygroscopic swelling rate.

[0013] This invention strictly controls the temperature and time of calcination of modified bentonite, which can control the moisture absorption expansion rate of bentonite to about 25%. The reason for controlling the moisture absorption expansion rate to about 25% is that at this expansion rate, the prepared putty will not crack due to excessive expansion of bentonite, thus reducing its waterproof performance. Moreover, an appropriate expansion rate can block micropores through the expansion of bentonite itself, thereby improving waterproof performance and enhancing the self-repairing ability of the putty layer.

[0014] Studies have shown that altering the calcination temperature and time will reduce waterproofing and self-healing properties to varying degrees. Analysis reveals that increasing the calcination temperature and reducing the calcination time can achieve a moisture expansion rate of around 25%. This is because the excessively high calcination temperature rapidly and extensively damages the microporous structure, but it doesn't increase the density of the bentonite. This results in insufficient space for the penetrating crystallizer to grow, leading to a decrease in waterproofing performance. Furthermore, density affects the durability of the putty layer; after repeated water absorption and loss, the waterproofing performance will severely decline. Conversely, decreasing the calcination temperature and increasing the calcination time can also achieve a moisture expansion rate of around 25%. This is because the longer calcination time increases the density of the bentonite, directly reducing its moisture expansion rate. However, the damage to the microporous structure is less, allowing moisture to directly penetrate the putty layer along the micropores, significantly reducing waterproofing performance. Moreover, the higher density prevents effective expansion and self-healing at cracks.

[0015] Furthermore, the active ingredient comprises the following raw materials in parts by weight: 3-9 parts sodium silicate, 1-3 parts carboxymethyl cellulose, and 1-3 parts nano-silica;

[0016] Preferably, the active ingredient comprises the following raw materials in parts by weight: 6 parts sodium silicate, 2 parts carboxymethyl cellulose, and 2 parts nano-silica.

[0017] This invention uses sodium silicate as a penetrating crystallizing masterbatch, which can effectively improve the waterproof performance of putty and enhance its self-healing properties. Analysis shows that sodium silicate, as an inorganic silicate, has excellent penetrating properties, effectively penetrating into the micropores of putty and concrete. Furthermore, sodium silicate can react with the hydration products of alkaline substances in putty or concrete to form dendritic crystals, which can fill the pores of the putty or concrete. In addition, the silicate ions in sodium silicate react chemically with calcium ions in the putty to form calcium silicate gel. The adhesive, a gel with excellent water resistance, allows sodium silicate to be added to the putty. The sodium silicate quickly penetrates the pores of the putty or concrete, reacting with alkaline substances to form dendritic crystals that block the pores and form calcium silicate gel with calcium ions, thus improving the putty's waterproof performance. Furthermore, when tiny cracks appear in the putty layer, the entry of moisture causes the putty to produce calcium ions and sodium silicate to produce silicate ions. The reaction between calcium ions and silicate ions forms calcium silicate gel at the cracks, filling them and achieving self-repair of the putty layer.

[0018] This invention improves the waterproofing and self-healing properties of putty by adding carboxymethyl cellulose (CMC). Analysis shows that CMC is a cellulose derivative with carboxymethyl substituents on its molecular chain, giving it a negative charge and strong adsorption capacity for cations such as calcium ions. When CMC is added to putty, it adsorbs a certain amount of calcium ions. These adsorbed calcium ions can react with silicate ions in the sodium silicate masterbatch to form calcium silicate gel, effectively sealing the micropores in the putty and improving its waterproofing. Furthermore, when tiny cracks appear in the putty, the CMC at the fracture point can quickly and extensively adsorb calcium ions. These adsorbed calcium ions then react with silicate ions to form calcium silicate gel, filling the cracks and enabling the putty to self-repair.

[0019] This invention improves the waterproofing and self-healing properties of putty by adding nano-silica. Analysis shows that nano-silica has excellent dispersibility; when added to putty, it disperses well within the putty layer. With the curing process, it forms a relatively stable network structure, stabilizing the dendritic crystals of sodium silicate within the putty layer, thus enhancing its waterproofing. Furthermore, nano-silica can form a network structure with carboxymethyl cellulose, promoting its network dispersion within the putty. This facilitates the dispersion of calcium silicate gel, further improving the putty's waterproofing. Moreover, when micro-cracks appear, the network dispersion of carboxymethyl cellulose allows for more efficient adsorption of calcium ions, further enhancing the putty's self-healing properties.

[0020] This invention adds sodium silicate, carboxymethyl cellulose, and nano-silica together. The three work synergistically to form dendritic crystals that improve the waterproof performance of the putty, while also using calcium silicate gel to repair cracks and improve the self-healing properties of the putty.

[0021] The second technical solution of this invention:

[0022] The preparation method of the above-mentioned self-healing waterproof material includes the following steps:

[0023] Weigh each raw material according to the stated mass proportions, mix the silicate cement, diatomaceous earth and modified bentonite to obtain a premix, then mix sodium silicate, carboxymethyl cellulose and nano silica to obtain an active ingredient, and finally mix the premix, active ingredient, lubricant and water-reducing agent to obtain the self-healing waterproof material.

[0024] The third technical solution of this invention:

[0025] The above-mentioned self-healing waterproof materials are used in wall construction.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1) The self-healing waterproof material prepared by this invention has good waterproof performance, with a 28-day seepage resistance pressure of 2.83 MPa and a 56-day secondary seepage resistance pressure of 1.65 MPa; moreover, the self-healing waterproof material prepared by this invention has excellent self-healing performance and can self-heal cracks smaller than 2.5 mm, which is far superior to existing self-healing putty.

[0028] 2) This invention uses diatomaceous earth and modified bentonite as raw materials, which can improve the waterproof performance of putty and enable the putty to self-repair;

[0029] 3) This invention adds sodium silicate, carboxymethyl cellulose and nano silica together. The three work synergistically to form dendritic crystals to improve the waterproof performance of the putty, while also using calcium silicate gel to repair cracks and improve the self-healing performance of the putty. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Unless otherwise specified, the term "part" in this invention refers to parts by weight; in the following examples, the raw materials are weighed according to 1 part = 1g.

[0032] In the following embodiments, a self-healing waterproof material comprises the following raw materials in parts by weight: 20-40 parts silicate cement, 10-20 parts diatomaceous earth, 10-20 parts modified bentonite, 5-15 parts active ingredient, 1-5 parts lubricant, and 1-5 parts water-reducing agent.

[0033] The modified bentonite is prepared by calcining the bentonite at 850℃ for 30 minutes.

[0034] The active ingredients include the following raw materials in parts by weight: 3-9 parts sodium silicate, 1-3 parts carboxymethyl cellulose, and 1-3 parts nano-silica.

[0035] In the following embodiments, the silicate cement is white silicate cement purchased from Jinan Zhongxin Chemical Co., Ltd.; the diatomaceous earth is high-purity diatomaceous earth purchased from Lingshou Qiangdong Mineral Products Processing Plant; the bentonite is 200-mesh bentonite purchased from Lingshou Ruifeng Mineral Products Co., Ltd.; the carboxymethyl cellulose is industrial-grade CMC purchased from Dacheng Yibo Chemical Co., Ltd.; the nano silica is nano silica purchased from Hubei Huifu Nanomaterials Co., Ltd.; the lubricant is thixotropic lubricant for gypsum cement mortar purchased from Jinan Junhai Chemical Co., Ltd.; and the water-reducing agent is polycarboxylate water-reducing agent purchased from Jinan Junhai Chemical Co., Ltd.

[0036] Example 1

[0037] A self-healing waterproof material

[0038] 1) Weigh each raw material according to the mass fractions recorded in Table 1, 1#;

[0039] 2) Calcine the bentonite weighed in step 1) at 850℃ for 30 min to obtain modified bentonite;

[0040] 3) Mix the silicate cement and diatomaceous earth weighed in step 1) with the modified bentonite obtained in step 2), stir for 30 minutes to obtain a premix;

[0041] 4) Mix the sodium silicate, carboxymethyl cellulose and nano silica weighed in step 1), stir for 30 minutes to obtain the active ingredient;

[0042] 5) Mix the premix obtained in step 3), the active ingredient obtained in step 4), the lubricant and water-reducing agent weighed in step 1), and stir for 30 minutes to obtain the self-healing waterproof material.

[0043] The modified bentonite obtained in step 2) was subjected to an expansion rate test, and the expansion rate was 25%.

[0044] Example 2

[0045] A self-healing waterproof material

[0046] Same as Example 1, except that each raw material is weighed according to the mass fractions recorded in Table 1, 2#.

[0047] Example 3

[0048] A self-healing waterproof material

[0049] Same as Example 1, except that each raw material is weighed according to the mass fractions recorded in Table 1, 3#.

[0050] Table 1 Raw material usage (parts)

[0051]

[0052]

[0053] Comparative Example 1

[0054] A type of putty material

[0055] 1) Weigh each raw material according to the mass fractions recorded in Table 1, 1#;

[0056] 2) Mix the silicate cement, diatomaceous earth and bentonite weighed in step 1) and stir for 30 minutes to obtain a premix;

[0057] 3) Mix the sodium silicate, carboxymethyl cellulose and nano silica weighed in step 1), stir for 30 minutes to obtain the active ingredient;

[0058] 4) Mix the premix obtained in step 2), the active ingredient obtained in step 3), the lubricant and water-reducing agent weighed in step 1), and stir for 30 minutes to obtain the putty material.

[0059] Comparative Example 2

[0060] A type of putty material

[0061] Same as Example 1, except that: step 2) involves calcining the bentonite weighed in step 1) at 1000°C for 12 minutes to obtain modified bentonite.

[0062] The modified bentonite obtained in step 2) was subjected to an expansion rate test, and the expansion rate was 25%.

[0063] Comparative Example 3

[0064] A type of putty material

[0065] Same as Example 1, except that: step 2) involves calcining the bentonite weighed in step 1) at 700°C for 75 minutes to obtain modified bentonite.

[0066] The modified bentonite obtained in step 2) was subjected to an expansion rate test, and the expansion rate was 25%.

[0067] Comparative Example 4

[0068] A type of putty material

[0069] Same as Example 1, except that: step 1) is to weigh each raw material according to the mass fractions recorded in Table 2.

[0070] Comparative Example 5

[0071] A type of putty material

[0072] Same as Example 1, except that: step 1) is to weigh each raw material according to the mass fractions recorded in Table 2@.

[0073] Comparative Example 6

[0074] A type of putty material

[0075] Same as Example 1, except that: step 1) is to weigh each raw material according to the mass fractions recorded in Table 2, 3@.

[0076] Comparative Example 7

[0077] A type of putty material

[0078] Same as Example 1, except that calcium chloride is used instead of sodium silicate.

[0079] Comparative Example 8

[0080] A type of putty material

[0081] Same as Example 1, except that hydroxypropyl methylcellulose is used instead of carboxymethyl cellulose.

[0082] Comparative Example 9

[0083] A type of putty material

[0084] Same as Example 1, except that nano-calcium oxide is used instead of nano-silica.

[0085] Table 2 Raw material usage (parts)

[0086]

[0087]

[0088] Effect verification

[0089] The putty materials (self-healing waterproof materials) prepared in Examples 1-3 and Comparative Examples 1-9 were tested according to the methods described in the national standard GB18445-2012. The test results are shown in Table 3.

[0090] Table 3 Performance Tests

[0091] Example 1 2.83 1.65 Example 2 2.83 1.63 Example 3 2.82 1.63 Comparative Example 1 1.32 0.94 Comparative Example 2 1.67 1.12 Comparative Example 3 1.63 1.08 Comparative Example 4 2.73 1.56 Comparative Example 5 2.18 1.41 Comparative Example 6 2.20 1.39 Comparative Example 7 2.37 1.43 Comparative Example 8 2.35 1.44 Comparative Example 9 2.40 1.41

[0092] The self-healing ability of the putty materials (self-healing waterproof materials) prepared in Examples 1-3 and Comparative Examples 1-9 was tested according to the self-sealing test method described in the national standard GB23445-2009. The specific test method was as follows: based on the self-sealing test method described in the national standard GB23445-2009, cracks of different widths (2.5mm, 2.0mm, 1.5mm, 1.0mm and 0.5mm) were cut with a paper knife to test the self-sealing ability. The test results are shown in Table 4.

[0093] Table 4 Performance Tests

[0094]

[0095]

[0096] Note: Failure means that when cutting with a 0.5mm paper knife, the crack cannot be sealed.

[0097] As can be seen from Tables 3 and 4, the self-healing waterproof material prepared by this invention has good waterproof performance, with a 28-day seepage resistance pressure of 2.83 MPa and a 56-day secondary seepage resistance pressure of 1.65 MPa. Moreover, the self-healing waterproof material prepared by this invention has excellent self-healing performance, capable of self-healing cracks smaller than 2.5 mm, which is far superior to existing self-healing putty (existing self-healing putty generally achieves the 0.5 mm self-healing capability recorded in the national standard).

[0098] As can be seen from Comparative Example 1, omitting the modification of bentonite significantly reduces the waterproof performance of the final putty material and makes it unable to self-repair cracks.

[0099] As can be seen from Comparative Examples 2 and 3, although changing the modification temperature and modification time of bentonite can also achieve an expansion rate of 25%, it will reduce the waterproof performance and self-healing performance of the putty material.

[0100] As can be seen from Comparative Example 4, diatomaceous earth is one of the key raw materials for achieving self-repair in this invention. Omitting the addition of diatomaceous earth will not seriously affect the waterproof performance of the putty material, but it will not be able to achieve self-repair of cracks.

[0101] As can be seen from Comparative Examples 5 to 9, the sodium silicate, carboxymethyl cellulose and nano-silica added together in this invention have a synergistic effect. None of them can be omitted. Omitting one of them or replacing one of the raw materials with other raw materials with similar effects will not achieve the technical effect of this invention.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A self-repairing waterproof material, characterized by, The raw materials include the following parts by weight: 20-40 parts silicate cement, 10-20 parts diatomaceous earth, 10-20 parts modified bentonite, 5-15 parts active ingredients, 1-5 parts lubricant, and 1-5 parts water-reducing agent. The modified bentonite is prepared by calcining the bentonite. The calcination treatment is carried out at a temperature of 800–900°C for 20–40 minutes. The active ingredients include the following raw materials in parts by weight: 3-9 parts sodium silicate, 1-3 parts carboxymethyl cellulose, and 1-3 parts nano-silica.

2. A method for preparing a self-repairing waterproof material according to claim 1, characterized in that, Includes the following steps: The silicate cement, diatomaceous earth, and modified bentonite are mixed to obtain a premix. Then, sodium silicate, carboxymethyl cellulose, and nano-silica are mixed to obtain an active ingredient. Finally, the premix, active ingredient, lubricant, and water-reducing agent are mixed to obtain the self-healing waterproof material.

3. The application of the self-healing waterproof material as described in claim 1 in wall construction.

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