A seepage-proof, low-shrinkage mortar and its preparation method

Abstract

This invention discloses a seepage-proof, low-shrinkage mortar and its preparation method. The seepage-proof, low-shrinkage mortar comprises, by weight, 45-60 parts of seepage-proof, low-shrinkage cementitious material; 130-180 parts of manufactured sand; 1-3 parts of water-repellent agent; and 40-60 parts of water. This invention uses green inorganic materials for preparation, exhibiting a micro-expansion effect, effectively avoiding the problem of large material shrinkage, while also improving the seepage resistance of the cementitious material, thus possessing the advantages of seepage prevention and low shrinkage.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic materials technology, specifically to a seepage-proof, low-shrinkage mortar and its preparation method. Background Technology

[0002] Building leaks have always been a thorny problem, commonly occurring in areas prone to water accumulation such as bathrooms, balconies, exterior walls, and basements. According to incomplete statistics, 35% of buildings experience leaks within two years of completion, and 55% of these leaks render the buildings unusable. Common waterproofing materials on the market are divided into inorganic and organic types. Inorganic waterproofing mortar has the advantages of low cost, the absence of toxic or harmful substances, and simple application. However, waterproofing mortar also has certain drawbacks, such as low strength, high shrinkage, and insufficient structural density. Traditional inorganic waterproof mortars use ordinary silicate cement as the main cementing material. However, ordinary silicate cement has a high drying shrinkage rate and is prone to cracking, which leads to its loss of waterproofing function. In contrast, the drying shrinkage rate of low-heat silicate cement at all ages is 50% to 70% of that of ordinary silicate cement, and the drying shrinkage rate after 28 days basically does not change. Low-heat silicate cement hydrates slowly, and its hydration products are more dense and have better durability. Therefore, this invention uses low-heat silicate cement as the main cementing material to prepare impermeable and low-shrinkage mortar. Summary of the Invention

[0003] To overcome the shortcomings and deficiencies of existing technologies, this invention provides an anti-seepage and low-shrinkage mortar and its preparation method. This anti-seepage and low-shrinkage mortar selects green inorganic materials and combines the characteristics of slow hydration of low-heat silicate cement, micro-expansion of high-magnesium low-heat silicate cement, and micro-expansion of ettringite-like products formed between gypsum and cement hydration products. The micro-expansion characteristic alleviates the material shrinkage problem and enables the material to form a dense structure. Furthermore, through the saponification reaction of hydrophobic material glyceryl stearate under alkaline conditions, a hydrophobic film is formed on the surface of the cementitious material, and sodium methylsilicate forms a hydrophobic layer on the surface of fine aggregates, giving the material excellent hydrophobic and anti-seepage properties.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] This invention discloses a seepage-proof, low-shrinkage mortar, comprising the following raw materials in parts by weight:

[0006]

[0007]

[0008] In some embodiments of the present invention, the seepage-proof low-shrinkage cementitious material comprises the following components by weight: 15-30 parts of low-heat silicate cement, 15-35 parts of high-magnesium low-heat silicate cement, 5-20 parts of rapid-hardening sulfoaluminate cement, 6-18 parts of silica fume, 8-12 parts of fly ash, 3-8 parts of blast furnace slag powder, 3-10 parts of gypsum, 2-8 parts of talc powder, 1-5 parts of glyceryl stearate, 0.3-0.8 parts of sodium silicate, 0.5-2.5 parts of defoamer, 1-5 parts of water-reducing agent, 0.3-0.8 parts of lithium carbonate, 0.8-2 parts of hydroxypropyl methylcellulose, and 1-5 parts of redispersible latex powder;

[0009] Preferably, the impermeable low-shrinkage cementitious material comprises the following components by weight: 20 parts low-heat silicate cement, 20 parts high-magnesium low-heat silicate cement, 10 parts rapid-hardening sulfoaluminate cement, 10 parts silica fume, 10 parts fly ash, 5 parts blast furnace slag powder, 5 parts gypsum, 5 parts talc powder, 2 parts glyceryl stearate, 0.5 parts sodium silicate, 1 part defoamer, 2 parts water-reducing agent, 0.5 parts lithium carbonate, 1 part hydroxypropyl methylcellulose, and 2 parts redispersible latex powder.

[0010] In some embodiments of the present invention, the mineral composition of the low-heat silicate cement is: 20-35 wt% C3S, 40-60 wt% C2S, 2-7 wt% C3A, and 10-20 wt% C4AF; the mineral composition of the high-magnesium low-heat silicate cement is: 20-35 wt% C3S, 35-60 wt% C2S, 1-8 wt% C3A, and 10-25 wt% C4AF, with an MgO content of 3-8 wt%; and the mineral composition of the rapid-hardening sulfoaluminate cement is: 50-70 wt% C4A3S, 10-35 wt% C2S, and 3-8 wt% C4AF.

[0011] In some embodiments of the present invention, the blast furnace slag powder is S95 grade blast furnace slag powder with a specific surface area of ​​500-700 m². 2 / kg.

[0012] In some embodiments of the present invention, the gypsum is industrial solid waste phosphogypsum with a specific surface area of ​​500–700 m². 2 / kg.

[0013] In some embodiments of the present invention, the silicon content of the silica fume is above 90%, and the specific surface area is 15-19 m². 2 / g.

[0014] In some embodiments of the present invention, the talc powder is industrial grade talc powder with a fineness of 3000 mesh.

[0015] In some embodiments of the present invention, the fly ash is Class I fly ash.

[0016] In some embodiments of the present invention, the gradation of the manufactured sand is as follows: 16% residue on a 2.36mm standard sieve, 14% residue on a 1.18mm standard sieve, 29% residue on a 0.6mm standard sieve, 23% residue on a 0.3mm standard sieve, 18% residue on a 0.075mm standard sieve, and a porosity of 36%.

[0017] In some embodiments of the present invention, the hydrophobic agent is sodium methylsilicate with a solid content of 40 wt%.

[0018] This invention also discloses a method for preparing an impermeable, low-shrinkage mortar, comprising the following steps:

[0019] S1. Low-heat silicate cement, high-magnesium low-heat silicate cement, rapid-hardening sulfoaluminate cement, silica fume, fly ash, blast furnace slag powder, gypsum, talc powder and glyceryl stearate are mixed evenly and then ball-milled to obtain powder; preferably, the ball milling speed is 200-400 r / s, the ball milling time is 10-40 min, and the powder particle size is 5-20 μm;

[0020] S2. Divide the water into two equal parts by mass. Add a water-repellent agent to one part of the water to obtain a diluted water-repellent agent solution. Set the other part of the water aside for later use.

[0021] S3. The sand is stirred at low speed, and a water-repellent agent dilution is sprayed during the stirring process to obtain fine aggregate; preferably, the low-speed stirring time is 120s.

[0022] S4. Pour the powder and additives obtained in S1 into the fine aggregate obtained in S3 and stir at low speed for 60 seconds. Then add another part of water from S2 and continue stirring at low speed for 30 seconds. Finally, stir at high speed for 60 seconds to obtain a mixed slurry.

[0023] S5. Pour the mixed slurry into the mold, vibrate to form, cure, and demold to obtain the impermeable low-shrinkage mortar.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention mainly uses low-heat silicate cement and high-magnesium low-heat silicate cement. Low-heat silicate cement has the characteristics of low shrinkage and low heat of hydration, which can alleviate material cracking; high-magnesium low-heat silicate cement has a micro-expansion effect, and the hydrated alum-like products generated by adding gypsum also have a micro-expansion effect, effectively avoiding the problem of large material shrinkage.

[0026] 2. This invention uses glyceryl stearate as a hydrophobic agent. By grinding the cementitious material and glyceryl stearate together, the surface of the cementitious material particles is uniformly coated with glyceryl stearate. Under alkaline conditions, glyceryl stearate hydrates into stearate and glycerol, forming a hydrophobic film, which improves the impermeability of the cementitious material. The fine aggregate is screened and reorganized, and the optimal gradation is obtained by using a close packing model. Sodium methylsilicate is uniformly sprayed on the surface of the fine aggregate to form a hydrophobic layer on the surface, giving the fine aggregate impermeability. Talc powder has a certain degree of hydrophobicity. The ultrafine silica fume and talc powder can fill the capillary pores inside the fine aggregate structure, reduce the porosity, and form a denser internal structure, further improving the impermeability.

[0027] 3. This invention ensures the waterproofing effect of both the powder and the fine aggregate, resulting in mortar with excellent waterproofing performance. Detailed Implementation

[0028] 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.

[0029] In this embodiment of the invention, the seepage-proof low-shrinkage cementitious material comprises the following components by mass parts: 20 parts of low-heat silicate cement, 20 parts of high-magnesium low-heat silicate cement, 10 parts of rapid-hardening sulfoaluminate cement, 10 parts of silica fume, 10 parts of fly ash, 5 parts of blast furnace slag powder, 5 parts of gypsum, 5 parts of talc powder, 2 parts of glyceryl stearate, 0.5 parts of sodium silicate, 1 part of defoamer, 2 parts of water-reducing agent, 0.5 parts of lithium carbonate, 1 part of hydroxypropyl methylcellulose, and 2 parts of redispersible latex powder.

[0030] In this embodiment of the invention, the mineral composition of the thermal silicate cement is: 20-35 wt% C3S, 40-60 wt% C2S, 2-7 wt% C3A, and 10-20 wt% C4AF; the mineral composition of the high-magnesium, low-heat silicate cement is: 20-35 wt% C3S, 35-60 wt% C2S, 1-8 wt% C3A, and 10-25 wt% C4AF, with an MgO content of 3-8 wt%; and the mineral composition of the rapid-hardening sulfoaluminate cement is: 50-70 wt% C4A3S, 10-35 wt% C2S, and 3-8 wt% C4AF.

[0031] In this embodiment of the invention, the blast furnace slag powder is S95 grade blast furnace slag powder with a specific surface area of ​​500-700 m². 2 / kg.

[0032] In this embodiment of the invention, the gypsum is industrial solid waste phosphogypsum with a specific surface area of ​​500–700 m². 2 / kg.

[0033] In this embodiment of the invention, the silicon content of the silica fume is above 90%, and the specific surface area is 15-19 m². 2 / g.

[0034] In this embodiment of the invention, the talc powder is industrial grade talc powder with a fineness of 3000 mesh.

[0035] In this embodiment of the invention, the fly ash is Class I fly ash.

[0036] In this embodiment of the invention, the gradation of the manufactured sand is as follows: 16% residue on a 2.36mm standard sieve, 14% residue on a 1.18mm standard sieve, 29% residue on a 0.6mm standard sieve, 23% residue on a 0.3mm standard sieve, 18% residue on a 0.075mm standard sieve, and a porosity of 36%.

[0037] In this embodiment of the invention, the hydrophobic agent is sodium methylsilicate with a solid content of 40 wt%.

[0038] In this embodiment of the invention, the preparation method of the seepage-proof low-shrinkage mortar includes the following steps:

[0039] S1. Low-heat silicate cement, high-magnesium low-heat silicate cement, rapid-hardening sulfoaluminate cement, silica fume, fly ash, blast furnace slag powder, gypsum, talc powder and glyceryl stearate are mixed evenly and then ball-milled in a ball mill at a speed of 200-400 r / s for 10-40 min to obtain powder with a particle size of 5-20 μm.

[0040] S2. Divide the water into two equal parts by mass. Add a water-repellent agent to one part of the water to obtain a diluted water-repellent agent solution. Set the other part of the water aside for later use.

[0041] S3. The sand is stirred at low speed, and a water-repellent agent dilution is sprayed during the stirring process to obtain fine aggregate; preferably, the low-speed stirring time is 120s.

[0042] S4. Pour the powder and additives obtained in S1 into the fine aggregate obtained in S3 and stir at low speed for 60 seconds. Then add another part of water from S2 and continue stirring at low speed for 30 seconds. Finally, stir at high speed for 60 seconds to obtain a mixed slurry.

[0043] S5. Pour the mixed slurry into the mold, vibrate to form, cure, and demold to obtain the impermeable low-shrinkage mortar.

[0044] Example 1

[0045] As a preferred embodiment of the present invention, the raw material composition of the anti-seepage low-shrinkage mortar disclosed in this embodiment is shown in Table 1.

[0046] Table 1. Raw material composition of the seepage-proof low-shrinkage mortar in Example 1

[0047] Raw material name Number of parts by weight / part Impermeable and low-shrinkage cementitious materials 50 Manufactured sand 180 Water repellent 3 water 60

[0048] According to the mass fractions of each raw material in Table 1, the preparation method described above was used to obtain anti-seepage and low-shrinkage mortar #1.

[0049] Example 2

[0050] As a preferred embodiment of the present invention, the raw material composition of the anti-seepage low-shrinkage mortar disclosed in this embodiment is shown in Table 2.

[0051] Table 2. Raw material composition of the seepage-proof low-shrinkage mortar in Example 2.

[0052]

[0053]

[0054] According to the mass fractions of each raw material in Table 2, the preparation method described above was used to obtain anti-seepage and low-shrinkage mortar #2.

[0055] Example 3

[0056] As a preferred embodiment of the present invention, the raw material composition of the anti-seepage low-shrinkage mortar disclosed in this embodiment is shown in Table 3.

[0057] Table 3. Raw material composition of the seepage-proof low-shrinkage mortar in Example 3.

[0058] Raw material name Number of parts by weight / part Impermeable and low-shrinkage cementitious materials 45 Manufactured sand 145 Water repellent 2 water 40

[0059] According to the mass fractions of each raw material in Table 3, the preparation method described above is used to obtain the anti-seepage and low-shrinkage mortar #3.

[0060] Example 4

[0061] As a preferred embodiment of the present invention, the raw material composition of the anti-seepage low-shrinkage mortar disclosed in this embodiment is shown in Table 4.

[0062] Table 4. Raw material composition of the seepage-proof low-shrinkage mortar in Example 4

[0063] Raw material name Number of parts by weight / part Impermeable and low-shrinkage cementitious materials 53 Manufactured sand 175 Water repellent 2.5 water 55

[0064] According to the mass fractions of each raw material in Table 4, the preparation method described above is used to obtain anti-seepage and low-shrinkage mortar #4.

[0065] Comparative Example 1

[0066] In this comparative example, except that ordinary silicate cement was used to replace low-heat silicate cement and high-magnesium low-heat silicate cement, everything else was the same as in Example 1, resulting in comparative mortar #1.

[0067] Comparative Example 2

[0068] In this comparative example, except that a common silicate hydrophobic agent was used to replace fatty acid glyceride as the hydrophobic agent, everything else was the same as in Example 1, resulting in comparative mortar #2.

[0069] Comparative Example 3

[0070] In this comparative example, except that polysiloxane was used to replace sodium methylsilicate as the water-repellent agent, everything else was the same as in Example 1, resulting in comparative mortar #3.

[0071] Test case

[0072] The mortars of Examples 1-4 and Comparative Examples 1-3 were subjected to impermeability tests and shrinkage tests, respectively.

[0073] Permeability Test: The permeability of the mortar was determined according to JGJ / T70-2009 "Standard for Test Methods of Basic Performance of Building Mortar". A digital display permeability tester (model SJS-1.5S) was used to test the permeability pressure of the mortar. The specimens had an upper diameter of 70 mm, a lower diameter of 80 mm, and a height of 30 mm. After molding, the specimens were allowed to stand at 20℃ for 24 hours before demolding, and then cured in a 20℃ curing water tank for 14 days. After curing, the specimens were removed, allowed to dry on the surface, sealed with wax, and then placed in the permeability tester for the permeability test. The test started with a pressure of 0.2 MPa, held constant for 2 hours, then increased to 0.3 MPa, and then increased by 0.1 MPa every hour thereafter. The test was stopped when water seepage appeared on the surface of one of the three specimens.

[0074] Shrinkage rate and tensile bond strength tests: refer to JGJ70-90 "Test methods for basic properties of building mortar".

[0075] Flexural strength and compressive strength tests: Refer to GB / T17671-2021 "Test Method for Strength of Cement Mortar". Formed using a 40*40*160mm triple mold, cured in a curing chamber at a temperature of 20℃±1℃ and humidity not less than 90%.

[0076] The relevant test results are shown in Table 5.

[0077] Table 5. Test results of mortars in Examples 1-4 and Comparative Examples 1-3

[0078]

[0079]

[0080] As shown in Table 5, the mortar obtained according to the formula provided by the present invention has excellent impermeability, low shrinkage rate, and the shrinkage of the mortar does not change much after 28 days; the compression-flexure ratio is less than 3.0, which further indicates that the material has good flexibility, which is conducive to improving crack resistance and effectively avoiding material cracking problems.

[0081] 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 the invention, 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 seepage-proof, low-shrinkage mortar, characterized in that, Including the following raw materials by weight: 45-60 parts of impermeable, low-shrinkage cementitious material; 130-180 parts of manufactured sand; 1-3 parts of water-repellent agent; 40-60 parts water; The impermeable, low-shrinkage cementitious material comprises the following components by weight: 15-30 parts of low-heat silicate cement, 15-35 parts of high-magnesium low-heat silicate cement, 5-20 parts of rapid-hardening sulfoaluminate cement, 6-18 parts of silica fume, 8-12 parts of fly ash, 3-8 parts of blast furnace slag powder, 3-10 parts of gypsum, 2-8 parts of talc powder, 1-5 parts of glyceryl stearate, 0.3-0.8 parts of sodium silicate, 0.5-2.5 parts of defoamer, 1-5 parts of water-reducing agent, 0.3-0.8 parts of lithium carbonate, 0.8-2 parts of hydroxypropyl methylcellulose, and 1-5 parts of redispersible latex powder; The mineral composition of the low-heat silicate cement is: 20~35wt%C3S, 40~60wt%C2S, 2~7wt%C3A, and 10~20wt%C4AF; the mineral composition of the high-magnesium low-heat silicate cement is: 20~35wt%C3S, 35~60wt%C2S, 1~8wt%C3A, and 10~25wt%C4AF, with an MgO content of 3~8wt%; the mineral composition of the rapid-hardening sulfoaluminate cement is: 50~70wt%C4A3S, 10~35wt%C2S, and 3~8wt%C4AF.

2. The anti-seepage low-shrinkage mortar according to claim 1, characterized in that, The impermeable, low-shrinkage cementitious material comprises the following components by weight: 20 parts low-heat silicate cement, 20 parts high-magnesium low-heat silicate cement, 10 parts rapid-hardening sulfoaluminate cement, 10 parts silica fume, 10 parts fly ash, 5 parts blast furnace slag powder, 5 parts gypsum, 5 parts talc powder, 2 parts glyceryl stearate, 0.5 parts sodium silicate, 1 part defoamer, 2 parts water-reducing agent, 0.5 parts lithium carbonate, 1 part hydroxypropyl methylcellulose, and 2 parts redispersible latex powder.

3. The anti-seepage low-shrinkage mortar according to claim 2, characterized in that, The blast furnace slag powder is S95 grade blast furnace slag powder with a specific surface area of ​​500~700 m². 2 / kg; the gypsum is industrial solid waste phosphogypsum with a specific surface area of ​​500~700m². 2 / kg.

4. The seepage-proof low-shrinkage mortar according to claim 1, characterized in that, The silica ash has a silicon content of over 90% and a specific surface area of ​​15-19 m². 2 / g.

5. The anti-seepage low-shrinkage mortar according to claim 1, characterized in that, The talc powder is industrial grade talc powder with a fineness of 3000 mesh; the fly ash is Grade I fly ash.

6. The anti-seepage low-shrinkage mortar according to claim 1, characterized in that: The manufactured sand gradation is as follows: 16% residue on a 2.36mm standard sieve, 14% residue on a 1.18mm standard sieve, 29% residue on a 0.6mm standard sieve, 23% residue on a 0.3mm standard sieve, 18% residue on a 0.075mm standard sieve, and a porosity of 36%.

7. The seepage-proof low-shrinkage mortar according to claim 1, characterized in that, The water-repellent agent is sodium methylsilicate with a solid content of 40 wt%.

8. A method for preparing an impermeable, low-shrinkage mortar according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Low-heat silicate cement, high-magnesium low-heat silicate cement, rapid-hardening sulfoaluminate cement, silica fume, fly ash, blast furnace slag powder, gypsum, talc powder and glyceryl stearate are mixed evenly and then ball-milled to obtain powder. S2. Divide the water into two equal parts by mass. Add a water-repellent agent to one part of the water to obtain a diluted water-repellent agent solution. Set the other part of the water aside for later use. S3. Mix the manufactured sand at low speed, and spray the water-repellent agent dilution during the mixing process to obtain fine aggregate; S4. Pour the powder obtained in S1, sodium silicate, defoamer, water-reducing agent, lithium carbonate, hydroxypropyl methylcellulose, and redispersible latex powder into the fine aggregate obtained in S3 and stir at low speed for 60 seconds. Then add another part of water from S2 and continue stirring at low speed for 30 seconds. Finally, stir at high speed for 60 seconds to obtain a mixed slurry. S5. Pour the mixed slurry into the mold, vibrate to form, cure, and demold to obtain the seepage-proof low-shrinkage mortar.

9. A method for preparing an impermeable, low-shrinkage mortar according to claim 8, characterized in that, In S1, the ball milling speed is 200~400 r / s, the ball milling time is 10~40 min, and the powder particle size is 5~20 μm.

10. The method for preparing a seepage-proof, low-shrinkage mortar according to claim 8, characterized in that, In step S3, the low-speed stirring time is 120 seconds.

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