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

Abstract

The invention discloses single-component waterproof mortar with low shrinkage rate and high compressive strength and a preparation method thereof. The single-component waterproof mortar is prepared from the following components in parts by weight: 380 to 420 parts of a cement-based material, 30 to 50 parts of an auxiliary cementing material, 530 to 570 parts of graded limestone tailing sand, 10 to 30 parts of a bonding enhancer, 2.2 to 2.6 parts of a water-retention thickening component, 2 to 5 parts of a reinforcing and toughening component, 1 to 4 parts of a nano reinforcing material, 4 to 7 parts of a functional material and 205 to 225 parts of water. The single-component waterproof mortar disclosed by the invention has the characteristics of low shrinkage rate and high compressive strength while having excellent waterproof performance.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a one-component waterproof mortar with a low shrinkage rate and high compressive strength and a preparation method thereof. Background Art

[0002] At present, using waterproof materials is the main way to solve the leakage and water penetration of aging existing buildings. According to the characteristics of materials, waterproof materials can be divided into rigid waterproof materials and flexible waterproof materials. Rigid waterproof materials are mainly polymer-modified cement-based materials, and flexible waterproof materials are most widely used in waterproof rolls and coatings. In contrast, the raw materials for preparing rigid waterproof materials are easy to obtain and the price is low. In addition, rigid waterproof materials themselves are non-toxic, odorless green environmental protection products, and the operation is simple during the construction process. Just add water and stir evenly to use. Based on this, rigid waterproof materials have gradually become a research hotspot in the field of building waterproofing.

[0003] In recent years, some problems have emerged in the use of existing rigid waterproof materials: 1) The main cementitious material in its preparation process is Portland cement, but this cement will produce large shrinkage deformation during the hydration and hardening process, which will easily separate the new and old interface joints from the foundation interface, resulting in secondary cracks and affecting the waterproof effect; 2) In order to ensure the bonding performance of the waterproof material, a large amount of redispersible latex powder and some ether substances are usually added to the cementitious material as modifiers, and this measure greatly reduces the mechanical properties of the cement-based material; 3) In order to reduce production costs, the use of a large amount of alternative cementitious 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 a waterproof mortar with better comprehensive performance through optimizing the mix design. Summary of the Invention

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

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

[0007] On the one hand, the present invention provides a one-component waterproof mortar with a low shrinkage rate and high compressive strength, including the following components in parts by weight: 380-420 parts of cement-based material, 30-50 parts of auxiliary cementitious material, 530-570 parts of graded limestone tailing sand, 10-30 parts of bonding enhancer, 2.2-2.6 parts of water retention and thickening component, 2-5 parts of strengthening and toughening component, 1-4 parts of nano-enhancing 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 slightly expanded low-heat cement with a mass ratio of (5.66 - 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 slightly expanded low-heat cement includes C2S, C4AF, and C4A3S, the C2S content is 38 wt%, the C4AF content is 6 wt%, the C4A3S content is 28 wt%, and the specific surface area of the slightly expanded low-heat cement > 400 m 2 / kg.

[0010] Furthermore, the supplementary cementitious material is argillaceous coal gangue;

[0011] The argillaceous coal gangue is the coal gangue calcined at 750 °C for 2 h, with an Al2O3 content of 22 wt% and an SiO2 content of 63%.

[0012] Furthermore, the graded limestone tailings sand is composed of coarse sand, medium sand, and fine sand obtained by crushing and screening limestone tailings, and the mass ratio of coarse sand, medium sand, and fine sand is (19 - 20):(24 - 26):(10 - 11);

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

[0014] Furthermore, the bonding enhancer is redispersible latex powder; the water retention and thickening component is composed of cellulose ether and starch ether with 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; the starch ether is hydroxypropyl starch ether.

[0016] Furthermore, the strengthening 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, add polypropylene fiber to acetic acid solution with a concentration of 1 - 1.5 mol / l and soak for 3 - 4 h, then wash with distilled water and dry at 50 - 60 °C to constant weight; SA2. Prepare a mixed solution of nano-metakaolin and water, and perform ultrasonic dispersion treatment for 5 - 10 minutes to obtain a dispersion liquid, and the mass fraction of nano-metakaolin in the mixed solution is 1 - 1.5 wt%; SA3. Coat the dispersion liquid on the surface of the dried polypropylene fiber and dry at 40 - 50 °C to obtain the polypropylene fiber coated with nano-clay.

[0018] Further, the nano-enhanced material is modified nano-calcium carbonate;

[0019] The preparation method of the modified nano-calcium carbonate is as follows: SB1. Add 50 g of nano-calcium carbonate into 450 ml of deionized water to obtain a nano-calcium carbonate dispersion; SB2. Weigh 3 g of a mixed solution of triethanolamine and triisopropanolamine and add it to the nano-calcium carbonate dispersion. Stir at room temperature for 5 - 6 h, then perform high-speed centrifugation, washing and drying to obtain the modified nano-calcium carbonate. The mass ratio of triethanolamine to triisopropanolamine in the mixed solution of triethanolamine and triisopropanolamine is 1:1.

[0020] Further, the functional material is composed of an organosilicon defoamer, a silicate water repellent and a shrinkage-reducing polycarboxylate water reducer in a mass ratio of (3 - 5):(3 - 5):(2 - 4). Among them, the shrinkage-reducing polycarboxylate water reducer is a superplasticizer grafted with special units having a shrinkage-reducing function on a carboxylic acid graft copolymer matrix.

[0021] On the other hand, the present invention provides a preparation method of a one-component waterproof mortar with low shrinkage rate and high compressive strength, including the following steps:

[0022] S1. Mix cement-based materials, auxiliary cementitious materials, graded limestone tailing sand, bonding and strengthening agents, water retention and thickening components, nano-enhanced materials and functional materials evenly to obtain a first dry powder;

[0023] S2. Add the strengthening and toughening components into the first dry powder in several times while stirring to obtain a second dry powder;

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

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

[0026] 1. The one-component waterproof mortar provided by the present invention can meet the requirements of bond strength and impermeability pressure in JC / T984 - 2011 "Polymer Cement Waterproof Mortar", and at the same time, can achieve a lower shrinkage rate and higher compressive strength compared with the type II polymer cement waterproof mortar in this standard.

[0027] 2. Based on the preliminary pre-tests, the present invention determines the contents of coarse sand, medium sand, and fine sand in the graded limestone tailing sand. During the preliminary pre-tests, the compressive strength and porosity are used as the evaluation criteria. When the mortar achieves a relatively high compressive strength and a relatively low porosity, the proportions of coarse sand, medium sand, and fine sand can usually achieve the close packing of the cementitious materials at this time, and the microstructure and waterproof effect of the hardened mortar will also be improved accordingly. In addition, the use of limestone tailing sand solves the problem of the accumulation of a large amount of tailings, which not only enriches the industrial layout but also is an effective way of comprehensive resource utilization.

[0028] 3. In the present invention, the polypropylene fiber coated with nano-clay can increase the surface roughness, enhance the hydrophilicity, increase the adhesion between the fiber and the matrix, and improve the interfacial transition zone, thereby enhancing the compressive strength and waterproof performance of the mortar; in addition, the nano-clay attached to the fiber surface can serve as a nucleation site to promote the formation of hydration products such as C-S-H gel, further enhancing the bridging ability of the fiber in the matrix. In addition, the modified nano-calcium carbonate has more excellent dispersion performance, and its nucleation and filling effects are enhanced.

[0029] 4. During the setting and hardening process, the hydration of ordinary Portland cement and slightly expanded low-heat cement is the main source of the strength of the waterproof mortar. The content of C3S in ordinary Portland cement is high, which can quickly hydrate to form C-S-H gel, connect the cementitious materials and aggregates, and densify the microstructure of the hardened paste. The content of C2S in slightly expanded low-heat cement is high, and the use of this cement can supplement the subsequent hydration. The synergistic use of the two cements can ensure the development of the mechanical properties of the waterproof mortar in both the early and late stages. In addition, the hydration products generated by the reaction of the aluminum phase in slightly expanded low-heat cement can offset part of the shrinkage generated during the hydration process of ordinary Portland cement. The use of argillaceous coal gangue not only reduces the cement consumption and manufacturing cost, enhances the impermeability of the mortar, and reduces the shrinkage rate, but also can generate a chemical synergistic effect with nano-calcium carbonate during the subsequent hydration to generate more hydration products and improve the comprehensive performance of the waterproof mortar. The simultaneous use of redispersible latex powder, cellulose ether, and starch ether can greatly improve the tensile bond performance of the waterproof mortar and prevent it from falling off during use. The use of shrinkage-reducing polycarboxylate water reducer not only improves the working performance and microstructure of the cement-based material but also can further reduce the shrinkage rate. Specific embodiments

[0030] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0031] Example 1

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

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

[0034]

[0035]

[0036] Example 2

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

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

[0039]

[0040]

[0041] Example 3

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

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

[0044]

[0045] Example 4

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

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

[0048]

[0049]

[0050] Comparative Example 1

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

[0052] Comparative Example 2

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

[0054] Comparative Example 3

[0055] In this comparative example, the components of the waterproof mortar are the same as those in Example 2, except that the auxiliary cementitious material (clay gangue) is not included and the ordinary Portland cement is 400 parts.

[0056] Test Example

[0057] The waterproof mortars of each example and comparative example were tested for compressive and flexural strengths, 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 Each Waterproof Mortar

[0059]

[0060]

[0061] As can be seen from the results in Table 5, the compressive and flexural strengths, impermeability pressure, bond strength, shrinkage rate, water absorption rate, flexibility, alkali resistance, heat resistance and frost resistance of the waterproof mortars provided in Examples 1 to 4 and Comparative Examples 1 to 3 can all meet the China National Building Materials Industry Standard JCT984-2011, and the preparation process is simple and easy to realize industrial production. In addition, compared with the existing waterproof mortars, the single-component waterproof mortar provided by the present invention has more excellent comprehensive performance, especially the shrinkage rate is significantly reduced and the mechanical properties (compressive and flexural strengths) are significantly improved.

[0062] Finally, it should be noted that the above examples are only the preferred examples of the present invention to illustrate the technical solutions of the present invention, rather than to limit it, and certainly not to limit the patent scope of the present invention; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of each example of the present invention; that is to say, any meaningless changes or polishing made on the main design idea and spirit of the present invention, as long as the technical problems solved are still the same as those of the present invention, should be included in the protection scope of the present invention; in addition, directly or indirectly applying the technical solutions of the present invention to other related technical fields shall also be included in the patent protection scope of the present invention by the same token.

Claims

1. A one-component waterproof mortar with low shrinkage rate and high compressive strength, characterized in that, Comprising the following components by weight parts: 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 bonding enhancer, 2.2 - 2.6 parts of water retention and thickening component, 2 - 5 parts of strengthening and toughening component, 1 - 4 parts of nano-enhancing material, 4 - 7 parts of functional material, and 205 - 225 parts of water.

2. The one-component waterproof mortar with low shrinkage rate and high compressive strength according to claim 1, characterized in that The cement-based material is composed of ordinary Portland cement and micro-expansion low-heat cement with 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 - 100 μm; the mineral composition of the slightly expanding low-heat cement includes C2S, C4AF and C4A3S, the C2S content is 38 wt%, the C4AF content is 6 wt%, and the C4A3S content is 28 wt%. The specific surface area of the slightly expanding low-heat cement > 400 m 2 / kg.

3. A one-component waterproof mortar with low shrinkage rate and high compressive strength according to claim 1, characterized in that, The auxiliary cementitious material is argillaceous coal gangue; The argillaceous coal gangue is the coal gangue calcined at 750 °C for 2 h, with an Al2O3 content of 22 wt% and an SiO2 content of 63%.

4. A one-component waterproof mortar with low shrinkage rate 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 obtained by crushing and screening limestone tailings, and the mass ratio of coarse sand, medium sand, and fine sand is (19 - 20):(24 - 26):(10 - 11); The particle size range of the coarse sand is 0.212 - 0.5 mm, the particle size range of the medium sand is 0.15 - 0.212 mm, and the particle size range of the fine sand is 0.09 - 0.15 mm.

5. A one-component waterproof mortar with low shrinkage rate and high compressive strength according to claim 1, characterized in that, The bonding enhancer is redispersible latex powder; the water retention and thickening component is composed of cellulose ether and starch ether with a mass ratio of (3 - 5):

1.

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

7. A one-component waterproof mortar with low shrinkage rate and high compressive strength according to claim 1, characterized in that, The strengthening 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, add polypropylene fiber into acetic acid solution with a concentration of 1 - 1.5 mol / l and soak for 3 - 4 h, then wash with distilled water and dry at 50 - 60 °C to constant weight; SA2. Prepare a mixed solution of nano-metakaolin and water, and perform ultrasonic dispersion treatment for 5 - 10 minutes to obtain a dispersion liquid, and the mass fraction of nano-metakaolin in the mixed solution is 1 - 1.5 wt%; SA3. Coat the dispersion liquid on the surface of the dried polypropylene fiber and dry at 40 - 50 °C to obtain the polypropylene fiber coated with nano-clay.

8. A one-component waterproof mortar with low shrinkage rate and high compressive strength according to claim 1, characterized in that, The nano-enhancing material is modified nano-calcium carbonate; The preparation method of the modified nano-calcium carbonate is as follows: SB1. Add 50 g of nano-calcium carbonate into 450 ml of deionized water to obtain a nano-calcium carbonate dispersion liquid; SB2. Weigh 3 g of a mixed solution of triethanolamine and triisopropanolamine and add it into the nano-calcium carbonate dispersion liquid, stir at room temperature for 5 - 6 h, then perform high-speed centrifugation, washing, and drying to obtain modified nano-calcium carbonate, and the mass ratio of triethanolamine and triisopropanolamine in the mixed solution of triethanolamine and triisopropanolamine is 1:

1.

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

10. The preparation method of a one-component waterproof mortar with low shrinkage rate and high compressive strength according to any one of claims 1 to 9, characterized in that, Including the following steps: S1. Mix the cement-based material, supplementary cementitious material, graded limestone tailings sand, bonding and reinforcing agent, water retention and thickening component, nano-reinforcing material and functional material evenly to obtain the first dry powder; S2. Add the strengthening and toughening component into the first dry powder in several times 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.

Images