Single-component waterproof mortar with low shrinkage and high compressive strength and preparation method thereof

Abstract

The application discloses a single-component waterproof mortar with low shrinkage and high compressive strength and a preparation method thereof. The single-component waterproof mortar comprises cement base material 380-420 parts by weight, auxiliary cementing material 30-50 parts by weight, graded limestone tailing sand 530-570 parts by weight, bonding enhancer 10-30 parts by weight, water-retaining thickening component 2.2-2.6 parts by weight, reinforcing and toughening component 2-5 parts by weight, nano reinforcing material 1-4 parts by weight, functional material 4-7 parts by weight and water 205-225 parts by weight. The single-component waterproof mortar has the characteristics of low shrinkage and high compressive strength while having excellent waterproof performance.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a single-component waterproof mortar with low shrinkage and high compressive strength, and its preparation method. Background Technology

[0002] Currently, using waterproofing materials is the primary way to solve leakage and water seepage in aging existing buildings. Based on their properties, waterproofing materials can be divided into rigid and flexible waterproofing materials. Rigid waterproofing materials are mainly polymer-modified cement-based materials, while flexible waterproofing materials, such as waterproof membranes and coatings, are the most widely used. Comparatively, rigid waterproofing materials have readily available and inexpensive raw materials. Furthermore, rigid waterproofing materials are non-toxic, odorless, and environmentally friendly products, and their application is simple—just add water and stir until dissolved. Based on these advantages, rigid waterproofing materials have gradually become a research hotspot in the field of building waterproofing.

[0003] In recent years, existing rigid waterproofing materials have revealed some problems during use: 1) The main cementing material in their preparation process is silicate cement, but this cement will produce large shrinkage deformation during the hydration and hardening process, which will make it easy for the interface between the new and old layers to separate from the base interface, thus producing secondary cracks and affecting the waterproofing effect; 2) In order to ensure the bonding performance of the waterproofing material, a large amount of redispersible latex powder and some ether substances are usually added to the cementing material as modifiers. This measure greatly reduces the mechanical properties of cement-based materials; 3) In order to reduce production costs, the use of a large number of alternative cementing materials will also reduce the early mechanical properties of the system.

[0004] Therefore, in order to solve some existing technical problems, it is necessary to develop waterproof mortar with better overall performance by optimizing the mix proportion. Summary of the Invention

[0005] In view of the defects and deficiencies in the existing technology, the present invention provides a single-component waterproof mortar with low shrinkage and high compressive strength and a preparation method thereof, which has excellent waterproof performance while also having the characteristics of low shrinkage and high compressive strength.

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

[0007] On the one hand, the present invention provides a single-component waterproof mortar with low shrinkage and high compressive strength, comprising the following components by weight: 380-420 parts of cement-based material, 30-50 parts of auxiliary cementitious material, 530-570 parts of graded limestone tailings sand, 10-30 parts of binder and reinforcing agent, 2.2-2.6 parts of water-retaining and thickening component, 2-5 parts of reinforcing and toughening component, 1-4 parts of nano-reinforcing material, 4-7 parts of functional material, and 205-225 parts of water.

[0008] Furthermore, the cement-based material is composed of ordinary Portland cement and micro-expansion low-heat cement in a mass ratio of (5.66 to 8.5):1;

[0009] The ordinary Portland cement is 425 ordinary Portland cement with a particle size range of 0.1–100 μm; the mineral composition of the micro-expansion low-heat cement includes C2S, C4AF, and C4A3S, with a C2S content of 38 wt%, a C4AF content of 6 wt%, and a C4A3S content of 28 wt%, and the specific surface area of ​​the micro-expansion low-heat cement is >400 m². 2 / kg.

[0010] Furthermore, the auxiliary cementing material is clayey coal gangue;

[0011] The clayey coal gangue is coal gangue calcined at 750℃ for 2 hours, with an Al2O3 content of 22wt% and a SiO2 content of 63%.

[0012] Furthermore, the graded limestone tailings sand is a mixture of coarse sand, medium sand and fine sand after limestone tailings have been crushed and screened, with the mass ratio of coarse sand, medium sand and fine sand being (19-20):(24-26):(10-11).

[0013] The coarse sand has a particle size range of 0.212–0.5 mm, the medium sand has a particle size range of 0.15–0.212 mm, and the fine sand has a particle size range of 0.09–0.15 mm.

[0014] Furthermore, the adhesive reinforcing agent is a redispersible latex powder; the water-retaining and thickening component is composed of cellulose ether and starch ether in a mass ratio of (3-5):1.

[0015] Furthermore, the redispersible latex powder is a copolymer of ethylene / vinyl acetate; the cellulose ether is hydroxypropyl methylcellulose with a viscosity of 100,000; and the starch ether is hydroxypropyl starch ether.

[0016] Furthermore, the reinforcing and toughening component is polypropylene fiber coated with nano-clay;

[0017] The preparation method of the polypropylene fiber coated with nano-clay is as follows: SA1, at room temperature, the polypropylene fiber is soaked in a 1-1.5 mol / L acetic acid solution for 3-4 hours, then washed with distilled water and dried at 50-60℃ to constant weight; SA2, a mixed solution of nano-kaolin and water is prepared and ultrasonically dispersed for 5-10 minutes to obtain a dispersion, wherein the mass fraction of nano-kaolin in the mixed solution is 1-1.5 wt%; SA3, the dispersion is coated on the surface of the dried polypropylene fiber and dried at 40-50℃ to obtain the polypropylene fiber coated with nano-clay.

[0018] Furthermore, the nano-reinforcing material is modified nano-calcium carbonate;

[0019] The modified nano-calcium carbonate is prepared as follows: SB1, 50g of nano-calcium carbonate is added to 450ml of deionized water to obtain a nano-calcium carbonate dispersion; SB2, 3g of a mixed solution of triethanolamine and triisopropanolamine is weighed and added to the nano-calcium carbonate dispersion, stirred at room temperature for 5-6 hours, and then centrifuged at high speed, washed and dried to obtain modified nano-calcium carbonate. The mass ratio of triethanolamine to triisopropanolamine in the mixed solution of triethanolamine and triisopropanolamine is 1:1.

[0020] Furthermore, the functional material is composed of an organosilicon defoamer, a silicate water-repellent agent, and a shrinkage-reducing polycarboxylate superplasticizer in a mass ratio of (3-5):(3-5):(2-4). The shrinkage-reducing polycarboxylate superplasticizer is a superplasticizer formed by grafting special units with shrinkage-reducing function onto a carboxylic acid graft copolymer matrix.

[0021] On the other hand, the present invention provides a method for preparing a single-component waterproof mortar with low shrinkage and high compressive strength, comprising the following steps:

[0022] S1. Mix cement-based materials, auxiliary cementitious materials, graded limestone tailings sand, binder, water-retaining and thickening components, nano-reinforcing materials and functional materials evenly to obtain the first dry powder;

[0023] S2. The reinforcing and toughening components are added to the first dry powder in multiple batches while stirring to obtain the second dry powder;

[0024] S3. Add water to the second dry powder and stir evenly to obtain the single-component waterproof mortar.

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

[0026] 1. The single-component waterproof mortar provided by this invention meets the requirements for bonding strength and anti-seepage pressure in JC / T984-2011 "Polymer Cement Waterproof Mortar", while achieving a lower shrinkage rate and higher compressive strength compared to Type II polymer cement waterproof mortar in the same standard.

[0027] 2. This invention determines the content of coarse, medium, and fine sand in graded limestone tailings sand based on preliminary experiments. Compressive strength and porosity were used as evaluation criteria during the preliminary experiments. When the mortar achieves high compressive strength and low porosity, the proportion of coarse, medium, and fine sand typically allows for close packing of the cementitious materials, thus improving the microstructure and waterproofing effect of the hardened mortar. Furthermore, the use of limestone tailings sand solves the problem of large-scale tailings accumulation, enriching the industrial layout and representing an effective way to comprehensively utilize resources.

[0028] 3. In this invention, the polypropylene fibers coated with nano-clay can improve surface roughness, enhance hydrophilicity, increase the adhesion between the fiber and the matrix, and improve the interfacial transition zone, thereby improving the compressive strength and waterproof performance of the mortar. Furthermore, the nano-clay adhering to the fiber surface can act as nucleation sites, promoting the formation of hydration products such as CSH gel, further enhancing the bridging ability of the fiber in the matrix. In addition, the modified nano-calcium carbonate exhibits superior dispersion properties, with enhanced nucleation and filling effects.

[0029] 4. During the setting and hardening process, the hydration of ordinary Portland cement and micro-expansion low-heat cement are the main sources of strength for waterproof mortar. Ordinary Portland cement has a high C3S content, which can quickly hydrate to form CSH gel, connecting the cementitious materials and aggregates, and densifying the microstructure of the hardened paste. Micro-expansion low-heat cement has a high C2S content, and its use can supplement subsequent hydration. The synergistic use of the two types of cement can simultaneously ensure the development of the early and later mechanical properties of the waterproof mortar. In addition, the hydration products generated by the aluminum phase reaction in micro-expansion low-heat cement can offset some of the shrinkage generated during the hydration process of ordinary Portland cement. The use of clayey coal gangue not only reduces cement usage and manufacturing costs, enhances the mortar's impermeability, and reduces shrinkage, but also has a chemical synergistic effect with nano-calcium carbonate in subsequent hydration, generating more hydration products and improving the overall performance of the waterproof mortar. The simultaneous use of redispersible latex powder, cellulose ether, and starch ether can significantly improve the tensile bonding properties of the waterproof mortar and prevent it from falling off during use. The use of shrinkage-reducing polycarboxylate superplasticizers not only improves the workability and microstructure of cement-based materials, but also further reduces the shrinkage rate. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] Example 1

[0032] As a preferred embodiment of the present invention, the composition of the single-component waterproof mortar with low shrinkage and high compressive strength in this embodiment is shown in Table 1 below.

[0033] Table 1. Composition of the single-component waterproof mortar in Example 1

[0034]

[0035]

[0036] Example 2

[0037] As a preferred embodiment of the present invention, the composition of the single-component waterproof mortar with low shrinkage and high compressive strength in this embodiment is shown in Table 2 below.

[0038] Table 2. Composition of the single-component waterproof mortar in Example 2

[0039]

[0040]

[0041] Example 3

[0042] As a preferred embodiment of the present invention, the composition of the single-component waterproof mortar with low shrinkage and high compressive strength in this embodiment is shown in Table 3 below.

[0043] Table 3. Composition of the single-component waterproof mortar in Example 3

[0044]

[0045] Example 4

[0046] As a preferred embodiment of the present invention, the composition of the single-component waterproof mortar with low shrinkage and high compressive strength in this embodiment is shown in Table 4 below.

[0047] Table 4. Composition of the single-component waterproof mortar in Example 4

[0048]

[0049]

[0050] Comparative Example 1

[0051] In this comparative example, the composition of the waterproof mortar is the same as that in Example 3, except that the cement-based material is only ordinary Portland cement (430 parts by weight).

[0052] Comparative Example 2

[0053] In this comparative example, the composition of the waterproof mortar is the same as that in Example 2, except that the graded limestone tailings sand is only coarse sand (550 parts by weight).

[0054] Comparative Example 3

[0055] The components of the waterproof mortar in this comparative example are the same as those in Example 2, except that it does not contain auxiliary cementitious materials (clay coal gangue) and the ordinary silicate cement is 400 parts.

[0056] Test case

[0057] The waterproof mortars of each embodiment and comparative example were tested for compressive and flexural strength, impermeability pressure, bond strength, shrinkage rate, water absorption rate, flexibility, alkali resistance, heat resistance and frost resistance. The test results are shown in Table 5.

[0058] Table 5 Test results of various waterproof mortars

[0059]

[0060]

[0061] As can be seen from the results in Table 5, the waterproof mortars provided in Examples 1-4 and Comparative Examples 1-3 all meet the requirements of the People's Republic of China Building Materials Industry Standard JCT984-2011 in terms of compressive and flexural strength, impermeability, bond strength, shrinkage rate, water absorption rate, flexibility, alkali resistance, heat resistance, and frost resistance. Furthermore, the preparation process is simple and easy to industrialize. In addition, compared with existing waterproof mortars, the single-component waterproof mortar provided by this invention has superior overall performance, especially with a significantly reduced shrinkage rate and significantly improved mechanical properties (compressive and flexural strength).

[0062] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit them, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A single-component waterproof mortar with low shrinkage and high compressive strength, characterized in that, The following components are included by weight: 380-420 parts cement-based materials, 30-50 parts auxiliary cementitious materials, 530-570 parts graded limestone tailings sand, 10-30 parts binder and reinforcing agent, 2.2-2.6 parts water-retaining and thickening components, 2-5 parts reinforcing and toughening components, 1-4 parts nano-reinforcing materials, 4-7 parts functional materials, and 205-225 parts water; The single-component cement-based material is composed of ordinary Portland cement and micro-expansion low-heat cement in a mass ratio of (5.66~8.5):1; The ordinary Portland cement is 425 ordinary Portland cement with a particle size range of 0.1~100μm; the mineral composition of the micro-expansion low-heat cement includes C2S, C4AF and C4A3S, with a C2S content of 38wt%, a C4AF content of 6wt%, and a C4A3S content of 28wt%, and the specific surface area of ​​the micro-expansion low-heat cement is >400 m². 2 / kg; The nano-reinforcing material is modified nano-calcium carbonate; The modified nano-calcium carbonate is prepared as follows: SB1, 50g of nano-calcium carbonate is added to 450ml of deionized water to obtain a nano-calcium carbonate dispersion; SB2, 3g of a mixed solution of triethanolamine and triisopropanolamine is weighed and added to the nano-calcium carbonate dispersion, stirred at room temperature for 5-6 hours, and then centrifuged at high speed, washed and dried to obtain modified nano-calcium carbonate. The mass ratio of triethanolamine to triisopropanolamine in the mixed solution of triethanolamine and triisopropanolamine is 1:

1.

2. The single-component waterproof mortar with low shrinkage and high compressive strength according to claim 1, characterized in that, The auxiliary cementing material is clayey coal gangue; The clayey coal gangue is coal gangue calcined at 750℃ for 2 hours, with an Al2O3 content of 22wt% and a SiO2 content of 63%.

3. The single-component waterproof mortar with low shrinkage and high compressive strength according to claim 1, characterized in that, The graded limestone tailings sand is a mixture of coarse sand, medium sand and fine sand after limestone tailings have been crushed and screened, with the mass ratio of coarse sand to medium sand to fine sand being (19~20):(24~26):(10~11). The coarse sand has a particle size range of 0.212~0.5mm, the medium sand has a particle size range of 0.15~0.212mm, and the fine sand has a particle size range of 0.09~0.15mm.

4. The single-component waterproof mortar with low shrinkage and high compressive strength according to claim 1, characterized in that, The binder is a redispersible latex powder; the water-retaining and thickening component is composed of cellulose ether and starch ether in a mass ratio of (3~5):

1.

5. The single-component waterproof mortar with low shrinkage and high compressive strength according to claim 4, characterized in that, The redispersible latex powder is a copolymer of ethylene / vinyl acetate; the cellulose ether is hydroxypropyl methylcellulose with a viscosity of 100,000; and the starch ether is hydroxypropyl starch ether.

6. The single-component waterproof mortar with low shrinkage and high compressive strength according to claim 1, characterized in that, The reinforcing and toughening component is polypropylene fiber coated with nano-clay; The preparation method of the polypropylene fiber coated with nano-clay is as follows: SA1, at room temperature, the polypropylene fiber is soaked in a 1~1.5mol / L acetic acid solution for 3~4h, then washed with distilled water and dried at 50~60℃ to constant weight; SA2, a mixed solution of nano-metakaolin and water is prepared, and ultrasonically dispersed for 5~10 minutes to obtain a dispersion, wherein the mass fraction of nano-metakaolin in the mixed solution is 1~1.5wt%; SA3. Coat the surface of the dried polypropylene fiber with the dispersion and dry it at 40~50℃ to obtain polypropylene fiber coated with nano clay.

7. The single-component waterproof mortar with low shrinkage and high compressive strength according to claim 1, characterized in that, The functional material is composed of an organosilicon defoamer, a silicate water-repellent agent, and a shrinkage-reducing polycarboxylate superplasticizer in a mass ratio of (3~5):(3~5):(2~4).

8. A method for preparing a single-component waterproof mortar with low shrinkage and high compressive strength according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Mix cement-based materials, auxiliary cementitious materials, graded limestone tailings sand, binder, water-retaining and thickening components, nano-reinforcing materials and functional materials evenly to obtain the first dry powder; S2. The reinforcing and toughening components are added to the first dry powder in multiple batches while stirring to obtain the second dry powder; S3. Add water to the second dry powder and stir evenly to obtain the single-component waterproof mortar.

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