Self-healing crystal impermeable high durability cement-based material, cement-based surface structure and method of paving

Abstract

The application discloses a self-repairing crystal anti-permeation high-durability cement-based material, a cement-based surface structure and a paving method thereof. The self-repairing crystal anti-permeation high-durability cement-based material comprises the following components in parts by weight: Portland cement 40-60 parts, wear-resistant aggregate 35-50 parts, water reducing agent 0.02-0.05 parts, retarder 0.2-0.5 parts, redispersible emulsion powder 1-2 parts, silica fume 1-2 parts, expanding agent 1-3 parts, chelating agent 1-6 parts and crystallization precipitant 1-6 parts; the total amount of the above components is 100 parts; the chelating agent is diethylenetriamine pentaacetic acid, and the weight ratio of the chelating agent to the crystallization precipitant is (0.5-2):1. The cement-based material has excellent self-repairing property, so that the strength, durability and anti-permeation property of the cement-based material are significantly improved.

Description

Technical Field

[0001] This application belongs to the field of building materials technology, specifically relating to self-healing crystalline waterproof high-durability cement-based materials, cement-based surface structures and their paving methods. Background Technology

[0002] Currently, cement-based materials remain the mainstream material in the construction industry. A large number of houses and municipal floors use cement-based materials. However, cement-based materials inevitably produce micro-cracks, which reduce the strength of the material. Furthermore, the existence of cracks also provides an opportunity for water molecules and chloride ions to penetrate, causing leakage. This further leads to a loss of material strength and affects durability.

[0003] Currently, there are penetrating crystalline waterproofing materials on the market that can be used to repair micro-cracks in cement-based materials. For example, Chinese patent CN110105025A discloses a cement-based penetrating crystalline waterproofing material. Its application method involves applying the waterproofing material to the surface of cement concrete. The active ingredients in the waterproofing material migrate into the cracks and pores of the cement concrete in an aqueous environment, undergoing a crystallization reaction to generate water-insoluble crystals that fill the cracks and pores, thus repairing the micro-cracks. However, when using this type of penetrating crystalline waterproofing material for repair, a coating process is required. Therefore, the inventors of this application conceived of developing a self-healing cement-based material that eliminates the need for the waterproofing material coating process, thereby simplifying the construction procedure. Summary of the Invention

[0004] The purpose of this application is to provide a self-healing crystalline impermeable high-durability cement-based material, a cement-based surface structure and its paving method. The cement-based material of this application can self-repair micro-cracks generated during use, simplifying the construction process while also possessing excellent impermeability and durability.

[0005] This application provides a self-healing crystalline waterproofing high-durability cement-based material, comprising the following components in parts by weight:

[0006] The composition comprises 40-60 parts silicate cement, 35-50 parts wear-resistant aggregate, 0.02-0.05 parts water-reducing agent, 0.2-0.5 parts retarder, 1-2 parts redispersible latex powder, 1-2 parts silica fume, 1-3 parts expansion agent, 1-6 parts chelating agent, and 1-6 parts crystallizing precipitant; totaling 100 parts of all the above components; wherein, the chelating agent is selected as diethylenetriaminepentaacetic acid, and the weight ratio of chelating agent to crystallizing precipitant is (0.5-2):1.

[0007] In some embodiments, 2 to 5 parts of chelating agent and 2 to 5 parts of crystallizing precipitant are used, wherein the weight ratio of chelating agent to crystallizing precipitant is (0.65 to 1.2):1.

[0008] In some embodiments, 3 to 5 parts of chelating agent and 2.5 to 5 parts of crystallizing precipitant are used, wherein the weight ratio of chelating agent to crystallizing precipitant is (0.75 to 1.2):1.

[0009] In some embodiments, the wear-resistant aggregate is selected from one or more of corundum, high-silica quartz sand, and ceramic particles.

[0010] In some embodiments, the water-reducing agent is selected from polycarboxylate water-reducing agents.

[0011] In some embodiments, sodium gluconate is selected as the retarder.

[0012] In some embodiments, the expanding agent is selected from calcium sulfoaluminate and / or calcium oxide.

[0013] In some embodiments, the crystallizing precipitant is selected from one or more of sodium silicate, sodium carbonate, and potassium fluoride.

[0014] Another aspect of this application provides a cement-based surface structure, the layered structure of which includes, in sequence, a concrete base layer, an interface layer, and a ground layer; wherein, the raw material of the ground layer is the aforementioned self-healing crystalline impermeable high-durability cement-based material.

[0015] This application further provides a method for paving the aforementioned cement-based pavement structure, including:

[0016] A bonding agent is applied to the concrete substrate to form an interface layer;

[0017] The above-mentioned cement-based material is mixed with water to form a slurry, which is then spread on the interface layer and cured to form a ground layer; wherein, 12 to 16 parts by weight of water are added to every 100 parts by weight of cement-based material.

[0018] Compared with the prior art, this application has the following advantages and beneficial effects:

[0019] 1. The cement-based material of this application possesses self-healing properties: When micro-cracks develop and water seeps into the cement-based material during curing and / or use, diethylenetriaminepentaacetic acid chelates with calcium ions in the cement-based material. The calcium ion chelate flows through the cracks with the water flow. During this process, the crystallizing precipitant reacts with the calcium ion chelate to form a large amount of crystalline precipitate, which fully fills the cracks, achieving self-healing. This excellent self-healing property significantly improves the strength, durability, and impermeability of the cement-based material.

[0020] 2. The strength of the cement-based material in this application is significantly improved: after the cracks are self-repaired, the physical strength is enhanced; at the same time, the calcium ions that chelate with the chelating agent mainly come from the cement hydration product calcium hydroxide and the expansion agent. The consumption of calcium ions can reduce the calcium hydroxide content in the cement-based material, thereby enhancing the physical strength.

[0021] 3. This application selects diethylenetriaminepentaacetic acid as a chelating agent. Compared with other common chelating agents and complexing agents, the combination of diethylenetriaminepentaacetic acid chelating agent and crystallizing precipitant can more significantly improve the physical strength, durability and impermeability of cement-based materials.

[0022] 4. In some embodiments of this application, sodium gluconate is selected as a retarder. While playing the role of a retarder, it can also promote the chelation of chelating agents and calcium ions, and promote the self-healing of cement-based materials.

[0023] 5. This application uses flexural strength and compressive strength to characterize the physical strength of the sample, uses the 28-day strength loss rate after 50 freeze-thaw cycles to characterize the durability of the sample, and uses the 28-day impermeability pressure to characterize the impermeability of the sample. Compared with other chelating agents (see Comparative Example 4), the flexural strength of this application can be increased by about 11%, the compressive strength can be increased by 17%, the strength loss rate can be reduced by about 21%, and the impermeability pressure can be increased by about 19% (see Example 5). Detailed Implementation

[0024] To make the purpose, technical solution and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments.

[0025] The self-healing crystalline waterproofing high-durability cement-based material provided in this application comprises the following components in parts by weight: 40-60 parts silicate cement, 35-50 parts wear-resistant aggregate, 0.02-0.05 parts water-reducing agent, 0.2-0.5 parts retarder, 1-2 parts redispersible latex powder, 1-2 parts silica fume, 1-3 parts expanding agent, 1-6 parts chelating agent, and 1-6 parts crystallizing precipitant; wherein, the chelating agent is selected as diethylenetriaminepentaacetic acid, and the weight ratio of the chelating agent to the crystallizing precipitant is (0.5-2):1. The total weight of all the above components is 100 parts.

[0026] When microcracks form in cement-based materials and water seeps in, diethylenetriaminepentaacetic acid chelates with calcium ions in the cement-based materials, forming a ring-shaped calcium ion chelate. This calcium ion chelate flows through the cracks with the water flow. During this process, a crystallizing precipitant reacts with the calcium ion chelate to form a large amount of crystalline precipitate, which fully fills the cracks, closing them and thus enhancing the strength, impermeability, and durability of the cement-based materials. In this application, the calcium ions mainly originate from calcium hydroxide, a cement hydration product, and the expanding agent. The consumption of calcium ions reduces the calcium hydroxide content in the cement-based materials, further enhancing the physical strength of the material.

[0027] In some embodiments, the silicate cement is selected as silicate cement with a strength grade of 52.5; the wear-resistant aggregate is selected as one or more of corundum, high silica quartz sand, and ceramic particles, with a particle size preferably of 10-20 mesh; the water-reducing agent is selected as polycarboxylate water-reducing agent; the retarder is selected as sodium gluconate; the expanding agent is selected as calcium sulfoaluminate and / or calcium oxide; and the crystallizing precipitant is selected as one or more of sodium silicate, sodium carbonate, and potassium fluoride.

[0028] In some embodiments, the silicate cement is 45-50 parts, 45-52 parts, or 50-52 parts. In some embodiments, the wear-resistant aggregate is 35.55-47.78 parts, 35.55-47.28 parts, 35.55-46.28 parts, or 35.55-37.77 parts. In some embodiments, the expanding agent is 1-2 parts.

[0029] Water-reducing agents are commonly used admixtures for cement-based materials, primarily used to improve the workability of these materials and reduce the unit water consumption. In this application, the water-reducing agent can be added at the conventional dosage. In some embodiments, the water-reducing agent is 0.02–0.03 parts or 0.03–0.05 parts.

[0030] Retarders are used to slow down the hardening time, reducing the heat of hydration generated during cement hydration and thus reducing crack formation. Retarders are also commonly used admixtures in cement-based materials; sodium gluconate is a suitable choice. In this application, the retarder is added at the conventional dosage; in some embodiments, the retarder is 0.2–0.4 parts. When sodium gluconate is chosen as the retarder, its dosage is preferably 0.3–0.5 parts. Excess sodium gluconate can promote the chelation of chelating agents with calcium ions, thereby promoting crack closure.

[0031] In this application, the weight percentage of chelating agent and crystallizing precipitant should not be too low. If it is too low, the improvement on the performance of cement-based materials will not be significant. The weight percentage of chelating agent and crystallizing precipitant should also not be too high. If it is too high, although the strength loss rate after freeze-thaw cycles can be significantly reduced and excellent impermeability pressure resistance can still be maintained, the strength will be somewhat reduced.

[0032] In some embodiments, the chelating agent comprises 2-5 parts, the crystallizing precipitant comprises 2-5 parts, and the weight ratio of the chelating agent to the crystallizing precipitant is (0.5-1.5):1, (0.55-1.5):1, or (0.65-1.2):1. In some embodiments, the chelating agent comprises 3-5 parts, the crystallizing precipitant comprises 2.5-5 parts, and the weight ratio of the chelating agent to the crystallizing precipitant is (0.65-1.2):1 or (0.75-1.2):1.

[0033] In some preferred embodiments, the self-healing crystalline waterproof high-durability cement-based material provided in this application comprises the following components in parts by weight: 45-52 parts silicate cement, 35-47 parts wear-resistant aggregate, 0.02-0.05 parts water-reducing agent, 0.2-0.4 parts retarder, 1-2 parts redispersible latex powder, 1-2 parts silica fume, 1-2 parts expanding agent, 2-5 parts chelating agent, and 2-5 parts crystallizing precipitant; wherein the chelating agent is selected as diethylenetriaminepentaacetic acid, and the weight ratio of the chelating agent to the crystallizing precipitant is (0.65-1.2):1. The total weight of all the above components is 100 parts.

[0034] In some preferred embodiments, the self-healing crystalline waterproof high-durability cement-based material provided in this application comprises the following components in parts by weight: 50-52 parts of silicate cement, 35-38 parts of wear-resistant aggregate, 0.03-0.05 parts of water-reducing agent, 0.2-0.4 parts of retarder, 1.5-2 parts of redispersible latex powder, 1-2 parts of silica fume, 1-2 parts of expanding agent, 3-5 parts of chelating agent, and 2.5-5 parts of crystallizing precipitant; wherein, the chelating agent is selected as diethylenetriaminepentaacetic acid, and the weight ratio of chelating agent to crystallizing precipitant is (0.75-1.2):1; the total weight of all the above components is 100 parts by weight.

[0035] The cement-based material provided in this application has a layered structure comprising, in sequence, a concrete base layer, an interface layer, and a ground layer; the raw material for the ground layer is the aforementioned cement-based material. The interface layer is used to enhance the adhesion of the concrete base layer, enabling a tighter bond between the concrete base layer and the ground layer; the interface layer may be selected from acrylic emulsion interface agents.

[0036] The method for paving cement-based pavement structures provided in this application includes:

[0037] (1) Apply an interface agent to the concrete substrate to form an interface layer; the interface agent can be an acrylic emulsion interface agent;

[0038] (2) Add water to the above cement-based materials to make a slurry, spread the slurry on the interface layer, and cure it to form a ground layer;

[0039] In some embodiments, 12 to 16 parts by weight of water are added to every 100 parts by weight of cement-based material; the slurry is spread to a thickness of 5 to 10 mm; and natural curing is carried out for a period of not less than 24 hours.

[0040] Several embodiments and comparative examples are provided below. The raw materials used in the embodiments and comparative examples are as follows:

[0041] Cement: Huaxin PI52.5 silicate cement; Abrasion-resistant aggregate: Commercially available 10-20 mesh high-silica quartz sand, with silica content ≥95%; Water-reducing agent: Longhu P20 powdered polycarboxylate water-reducing agent; Retarder: Commercially available industrial-grade sodium gluconate powder; Redispersible latex powder: Wacker 328 adhesive powder; Silica fume: Commercially available, particle size 825 mesh; Expanding agent: Commercially available calcium sulfoaluminate and commercially available calcium oxide in a 1:1 weight ratio; Chelating agent: Hengjingrui Chemical's diethylenetriaminepentaacetic acid, CAS: 67-43-6; Crystallizing precipitant: Pengcai Chemical sodium silicate powder; Ethylenediaminetetraacetic acid: white crystalline powder, commercially available industrial grade; Sodium methylsilicate: white powder, Jinan Yueruida Chemical.

[0042] The components and amounts of each component in the embodiments and comparative examples of this application are listed in Table 1 and Table 2, respectively.

[0043] Table 1. Components and dosage of each component in the embodiments.

[0044]

[0045] Table 2. Components and dosage of each component in the comparative examples.

[0046]

[0047]

[0048] The above-described embodiments and comparative products were prepared using the following method: raw materials were mixed according to their weight proportions, and then water was added and stirred to obtain a slurry, wherein the weight ratio of water to the raw material mixture was 15:100. The slurry was prepared into samples, and various performance indicators of the samples were tested. The 28-day flexural strength and 28-day compressive strength of the samples were tested according to standard GB / T 50081-2019; the samples were subjected to 50 freeze-thaw cycles using a slow freezing method according to standard GB / T 50082-2009, and then the 28-day compressive strength loss rate was tested; the 28-day impermeability pressure of the samples was tested according to standard GB / T 50082-2009. The performance indicator test data are listed in Tables 3 and 4, respectively. In this application, the 28-day compressive strength loss rate is used to characterize the durability of the samples, and the 28-day impermeability pressure is used to characterize the impermeability of the samples.

[0049] Table 3 Performance test data of the products in the examples

[0050]

[0051] Table 4 Performance test data of the comparative products

[0052]

[0053] As shown in Tables 1-4 above, adding chelating or complexing agents in combination with crystallizing precipitants can improve the strength, durability, and impermeability of the samples. While chelating or complexing agents alone can aggregate calcium ions through chelation or complexation, they are insufficient to form water-insoluble crystalline precipitates to fill cracks, resulting in no improvement in sample performance. Crystallizing precipitants alone can react with unaggregated calcium ions to form water-insoluble crystalline precipitates; however, due to the limited amount of precipitates that can be formed, their ability to fill cracks is limited, and the sample performance is similarly difficult to improve significantly.

[0054] In Comparative Example 4, ethylenediaminetetraacetic acid (EDTA) was selected as the chelating agent; in Comparative Example 5, sodium methylsilicate (MSC) was selected as the complexing agent; and in this application, diethylenetriaminepentaacetic acid (DTA) was selected as the chelating agent. Comparison shows that, compared to Comparative Examples 4 and 5, the strength, durability, and impermeability of the samples in this application's examples are further improved. That is, the combination of the DTA chelating agent and the crystallizing precipitant can significantly improve the strength, durability, and impermeability of cement-based materials.

[0055] The applicant believes that the mechanism by which the diethylenetriaminepentaacetic acid chelating agent can produce the above-mentioned technical effects is as follows:

[0056] Compared to ethylenediaminetetraacetic acid (EDTA) chelating agents, diethylenetriaminepentaacetic acid (DTA) has an additional amino and a carboxyl group in its structure, allowing it to combine with more calcium ions to form chelates. This increases the concentration and transport efficiency of calcium ions. The crystallizing precipitant, combined with the calcium-ion-dense chelate, can form a large amount of crystalline precipitate, effectively filling cracks. Compared to sodium methylsilicate complexes, DTA forms a more stable cyclic chelate structure with calcium ions, improving calcium ion transport efficiency and further contributing to the thorough filling of cracks.

[0057] Note that the above are merely preferred embodiments and the technical principles employed in this application. Those skilled in the art will understand that this application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of this application, all of which fall within the scope of protection of this application.

Claims

1. Self-repairing crystal impermeable high durability cementitious material, characterized by comprising The following components by weight: 50-52 parts of Portland cement, 35-38 parts of wear-resistant aggregate, 0.02-0.05 parts of water reducing agent, 0.2-0.5 parts of retarder, 1-2 parts of re-dispersible emulsion powder, 1-2 parts of silica fume, 1-3 parts of expanding agent, 3-5 parts of chelating agent, 2.5-5 parts of crystallization precipitant; the total of all the components is 100 parts; wherein the crystallization precipitant is sodium silicate, the chelating agent is diethylene triamine pentaacetic acid, and the weight ratio of the chelating agent and the crystallization precipitant is (0.75-1.2) : 1; The wear-resistant aggregate is selected from 10-20 mesh high-silicon quartz sand, wherein the content of silicon dioxide is ≥ 95%; The water reducing agent is selected from polycarboxylic acid water reducing agent; The retarder is selected from sodium gluconate; The expanding agent is a compound of calcium sulphoaluminate and calcium oxide in a weight ratio of 1:

1.

2. Cement base surface structure, characterized in that: The layered structure comprises a concrete base layer, an interface layer and a ground layer in sequence; the raw material of the ground layer is the cement-based material of claim 1.

3. A method of laying a cementitious flooring structure, characterised in that, It comprises: Brushing the interface agent on the concrete base layer to form the interface layer; The cement-based material of claim 1 is mixed with water to form a slurry, and the slurry is spread on the interface layer to form the ground layer after curing; wherein 12-16 parts of water is added to 100 parts of the cement-based material by weight.

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