A compressive dry-mixed mortar and its preparation method

Abstract

This invention relates to the field of building materials technology, and proposes a compressive strength dry-mixed mortar and its preparation method. The compressive strength dry-mixed mortar comprises the following components in parts by weight: 40-50 parts cement, 25-35 parts sand, 10-15 parts glass powder, 1-5 parts stone powder, 1-2 parts redispersible latex powder, 1-3 parts modified polypropylene fiber, 0.5-1.5 parts thickener, 5-10 parts expanding agent, and 1-2 parts water-reducing agent; the modified polypropylene fiber is polypropylene fiber first modified with an aminosilane coupling agent and then modified with 2,5-disulfonylbenzaldehyde. Through the above technical solution, the problem of low compressive strength in existing dry-mixed mortars is solved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a compressive-resistant dry-mixed mortar and its preparation method. Background Technology

[0002] Mortar refers to the mortar that binds bricks, stones, blocks, etc., into a complete masonry structure. It is widely used for building exterior wall insulation, interior decoration and repair, etc. Mortar is divided into cement mortar, cement-mixed mortar, and premixed mortar. According to the production method of premixed mortar, it is further divided into two main categories: wet-mixed mortar and dry-mixed mortar.

[0003] Dry-mixed mortar is a new type of building material that has developed in my country in recent years. It has the advantages of centralized production, stable quality, convenient construction, and only requires the addition of water and mixing on-site. Dry-mixed mortar is a solid mixture made by mixing cement, sand, admixtures, and additives in a certain proportion.

[0004] In existing technologies, the durability and workability of dry-mixed mortar are generally improved by adding high-strength and tough polypropylene fibers, which can not only prevent cracking but also improve the deformation capacity of the matrix. However, polypropylene fibers have poor dispersibility and tend to agglomerate, leading to a decrease in the compressive strength of the matrix. Summary of the Invention

[0005] This invention proposes a compressive strength dry-mixed mortar and its preparation method, which solves the problem of low compressive strength of dry-mixed mortar in related technologies.

[0006] The technical solution of the present invention is as follows:

[0007] A compressive strength dry-mixed mortar comprises the following components in parts by weight: 40-50 parts cement, 25-35 parts sand, 10-15 parts glass powder, 1-5 parts stone powder, 1-2 parts redispersible latex powder, 1-3 parts modified polypropylene fiber, 0.5-1.5 parts thickener, 5-10 parts expansion agent, and 1-2 parts water-reducing agent;

[0008] The modified polypropylene fiber is a polypropylene fiber that has been modified by an aminosilane coupling agent and then by 2,5-disulfonylbenzaldehyde.

[0009] As a further technical solution, the raw materials for the modified polypropylene fiber include polypropylene fiber, aminosilane coupling agent, and 2,5-disulfonylbenzaldehyde in a mass ratio of 1:0.1:0.3~0.8.

[0010] As a further technical solution, the aminosilane coupling agent includes one or both of KH-550 and KH-602.

[0011] As a further technical solution, the preparation method of the modified polypropylene fiber includes the following steps:

[0012] S1. Disperse polypropylene fibers in water, add aminosilane coupling agent, and modify them to obtain aminosilane coupling agent modified polypropylene fibers.

[0013] S2. The aminosilane coupling agent modified polypropylene fiber is mixed with 2,5-disulfonylbenzaldehyde and solvent, and reacted to obtain modified polypropylene fiber.

[0014] As a further technical solution, the modification temperature in S1 is 55~65℃, and the modification time is 2~4h.

[0015] As a further technical solution, the reaction temperature in S2 is 120~130℃ and the time is 2~4h.

[0016] As a further technical solution, the mass ratio of glass powder to stone powder is 4:1.

[0017] This invention uses glass powder and stone powder to ensure that the mortar has a certain strength. When the two are used together, they can have a dual effect: while enhancing the strength and density of the mortar, they can also reduce the pollution to the surrounding environment caused by the accumulation of waste glass and waste stone.

[0018] As a further technical solution, the thickener includes one or both of methyl hydroxyethyl cellulose ether and methyl hydroxypropyl cellulose ether.

[0019] This invention uses one or both of methyl hydroxyethyl cellulose ether and methyl hydroxypropyl cellulose ether as a thickener, which functions to retain water, thicken, and improve workability. Good water retention ensures sufficient water in the mortar, allowing for complete cement hydration and reducing mortar sanding, powdering, and low strength. The significant thickening effect meets workers' requirements for mortar consistency, maintaining a longer workable time and facilitating construction. Furthermore, the thickening effect greatly enhances the structural strength of the mortar.

[0020] As a further technical solution, the water-reducing agent includes one or two of naphthalene-based water-reducing agents and polycarboxylate water-reducing agents.

[0021] The present invention also proposes a method for preparing compressive dry-mixed mortar, wherein the components in the specified mass fractions are mixed evenly to obtain dry-mixed mortar.

[0022] The working principle and beneficial effects of this invention are as follows:

[0023] 1. This invention utilizes polypropylene fibers that are first modified with an aminosilane coupling agent and then modified with 2,5-disulfonylbenzaldehyde, thereby improving the compressive strength of dry-mixed mortar. The reason is that after modification with the aminosilane coupling agent, the polypropylene fibers have amino groups on their surface. When modified with 2,5-disulfonylbenzaldehyde, the carbonyl groups in the 2,5-disulfonylbenzaldehyde react with the amino groups, resulting in sulfonic acid groups on the polypropylene fiber surface. This increases the surface's hydrophilicity and improves the dispersibility of the polypropylene fibers. Simultaneously, the introduction of sulfonic acid groups slows down the transformation of the hydrated gel into crystals, which is beneficial for forming more complete crystals and improving crystal compactness, thus achieving the effect of improving the compressive strength of dry-mixed mortar.

[0024] 2. The present invention limits the raw materials of modified polypropylene fiber to polypropylene fiber, aminosilane coupling agent and 2,5-disulfonylbenzaldehyde in a mass ratio of 1:0.1:0.3~0.8, which further improves the compressive strength of dry-mixed mortar. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] The parameters of the raw materials in the following examples and comparative examples are as follows:

[0027] The cement is PO 42.5 ordinary Portland cement;

[0028] The sand is river sand with a fineness modulus of 2.2;

[0029] The glass powder is 325 mesh glass powder;

[0030] The stone powder is 150-mesh potassium feldspar powder with a density of 9.5 g / cm³. 3 K2O content > 86.5 wt%;

[0031] The redispersible latex powder is Wacker Chemie 328 redispersible latex powder from Germany;

[0032] The length of the polypropylene fiber is 3mm;

[0033] The expansive agent is a calcium sulfoaluminate type concrete expansive agent, purchased from Foshan Xinqi Tuoda New Material Group Co., Ltd.

[0034] The naphthalene-based water-reducing agent is naphthalene-based water-reducing agent FDN-C;

[0035] The polycarboxylate superplasticizer is polycarboxylate superplasticizer 540P.

[0036] Example 1

[0037] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 60℃, add 0.3g of KH-550 and continue stirring for 3h. Separate the fiber and dry it at 80℃ for 12h. Then, mix it with 0.3g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide and react at 125℃ for 3h. Separate the fiber, wash it three times with anhydrous ethanol, and dry it at 80℃ for 10h to obtain modified polypropylene fiber.

[0038] S2. Mix 45 parts cement, 30 parts sand, 12 parts glass powder, 3 parts stone powder, 1.5 parts redispersible latex powder, 2 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0039] Example 2

[0040] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 55℃, add 0.3g of KH-602 and continue stirring for 4h. Separate the fiber and dry it at 80℃ for 12h. Then, mix it with 0.3g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide and react at 120℃ for 4h. Separate the fiber, wash it twice with anhydrous ethanol, and dry it at 70℃ for 12h to obtain modified polypropylene fiber.

[0041] S2. Mix 40 parts cement, 25 parts sand, 10 parts glass powder, 1 part stone powder, 1 part redispersible latex powder, 1 part modified polypropylene fiber, 0.5 parts methyl hydroxypropyl cellulose ether, 5 parts expansion agent, and 1 part polycarboxylate superplasticizer evenly to obtain dry-mixed mortar.

[0042] Example 3

[0043] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 65℃, add 0.1g of KH-550 and 0.2g of KH-602 and continue stirring for 2h. Separate the fiber and dry it at 80℃ for 12h. Then, mix it with 0.3g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide and react at 130℃ for 2h. Separate the fiber, wash it three times with anhydrous ethanol, and dry it at 80℃ for 10h to obtain modified polypropylene fiber.

[0044] S2. Mix 50 parts cement, 35 parts sand, 15 parts glass powder, 5 parts stone powder, 2 parts redispersible latex powder, 3 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 0.5 parts methyl hydroxypropyl cellulose ether, 10 parts expansion agent, 1.5 parts naphthalene-based water-reducing agent, and 0.5 parts polycarboxylate water-reducing agent evenly to obtain dry-mixed mortar.

[0045] Example 4

[0046] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 60℃, add 0.3g of KH-550 and continue stirring for 3h. Separate the fiber and dry it at 80℃ for 12h. Then, mix it with 0.3g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide and react at 125℃ for 3h. Separate the fiber, wash it three times with anhydrous ethanol, and dry it at 80℃ for 10h to obtain modified polypropylene fiber.

[0047] S2. Mix 45 parts cement, 30 parts sand, 10 parts glass powder, 5 parts stone powder, 1.5 parts redispersible latex powder, 2 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0048] Example 5

[0049] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 60℃, add 0.3g of KH-550 and continue stirring for 3h. Separate the fiber and dry it at 80℃ for 12h. Then, mix it with 0.3g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide and react at 125℃ for 3h. Separate the fiber, wash it three times with anhydrous ethanol, and dry it at 80℃ for 10h to obtain modified polypropylene fiber.

[0050] S2. Mix 45 parts cement, 30 parts sand, 14 parts glass powder, 1 part stone powder, 1.5 parts redispersible latex powder, 2 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0051] Example 6

[0052] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 60℃, add 0.3g of KH-550 and continue stirring for 3h. Separate the fiber and dry it at 80℃ for 12h. Then, mix it with 0.9g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide and react at 125℃ for 3h. Separate the fiber, wash it three times with anhydrous ethanol, and dry it at 80℃ for 10h to obtain modified polypropylene fiber.

[0053] S2. Mix 45 parts cement, 30 parts sand, 12 parts glass powder, 3 parts stone powder, 1.5 parts redispersible latex powder, 2 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0054] Example 7

[0055] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 60℃, add 0.3g of KH-550 and continue stirring for 3h. Separate the fiber and dry it at 80℃ for 12h. Then, mix it with 1.5g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide and react at 125℃ for 3h. Separate the fiber, wash it three times with anhydrous ethanol, and dry it at 80℃ for 10h to obtain modified polypropylene fiber.

[0056] S2. Mix 45 parts cement, 30 parts sand, 12 parts glass powder, 3 parts stone powder, 1.5 parts redispersible latex powder, 2 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0057] Example 8

[0058] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 60℃, add 0.3g of KH-550 and continue stirring for 3h. Separate the fiber and dry it at 80℃ for 12h. Then, mix it with 2.4g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide and react at 125℃ for 3h. Separate the fiber, wash it three times with anhydrous ethanol, and dry it at 80℃ for 10h to obtain modified polypropylene fiber.

[0059] S2. Mix 45 parts cement, 30 parts sand, 12 parts glass powder, 3 parts stone powder, 1.5 parts redispersible latex powder, 2 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0060] Example 9

[0061] S1. Mix 3g of polypropylene fiber with 50mL of water and stir at 500rpm for 1h. Then, heat to 60℃, add 0.3g of KH-550 and continue stirring for 3h. Separate the fiber, dry at 80℃ for 12h, mix with 3g of 2,5-disulfonylbenzaldehyde and 40mL of dimethyl sulfoxide, react at 125℃ for 3h, separate the fiber, wash three times with anhydrous ethanol, and dry at 80℃ for 10h to obtain modified polypropylene fiber.

[0062] S2. Mix 45 parts cement, 30 parts sand, 12 parts glass powder, 3 parts stone powder, 1.5 parts redispersible latex powder, 2 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0063] Comparative Example 1

[0064] Mix 45 parts cement, 30 parts sand, 12 parts glass powder, 3 parts stone powder, 1.5 parts redispersible latex powder, 2 parts polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0065] Comparative Example 2

[0066] S1. Mix 3g of polypropylene fiber with 50mL of water, stir at 500rpm for 1h, heat to 60℃, add 0.3g of KH-550 and continue stirring for 3h, separate the fiber, and dry at 80℃ for 12h to obtain modified polypropylene fiber.

[0067] S2. Mix 45 parts cement, 30 parts sand, 12 parts glass powder, 3 parts stone powder, 1.5 parts redispersible latex powder, 2 parts modified polypropylene fiber, 1 part methyl hydroxyethyl cellulose ether, 7 parts expansion agent, and 1.5 parts naphthalene-based water-reducing agent evenly to obtain dry-mixed mortar.

[0068] The dry-mixed mortars obtained in Examples 1-9 and Comparative Examples 1-2 were mixed with water at a water-cement ratio (mass ratio of water to dry-mixed mortar) of 0.15, poured into molds, and cured at 20°C and 95% relative humidity until the required age. The compressive strength was then tested according to the method in JGJ / T 70-2009, and the test results are recorded in Table 1.

[0069] Table 1 Compressive Strength

[0070]

[0071] As can be seen from Table 1, the dry-mixed mortar provided by the present invention has high compressive strength.

[0072] Compared to Comparative Examples 1 and 2, Example 1 used polypropylene fibers that were first modified with an aminosilane coupling agent and then modified with 2,5-disulfonylbenzaldehyde, while Comparative Example 1 used unmodified polypropylene fibers, and Comparative Example 2 used polypropylene fibers modified with an aminosilane coupling agent. The 28-day compressive strength of the dry-mixed mortar obtained in Example 1 was higher than that in Comparative Examples 1 and 2. This indicates that polypropylene fibers modified with an aminosilane coupling agent and then modified with 2,5-disulfonylbenzaldehyde can improve the compressive strength of dry-mixed mortar.

[0073] Compared with Examples 6-9, the mass ratio of polypropylene fiber, aminosilane coupling agent, and 2,5-disulfonylbenzaldehyde in Example 1 was 1:0.1:0.1; in Example 6 it was 1:0.1:0.3; in Example 7 it was 1:0.1:0.5; in Example 8 it was 1:0.1:0.8; and in Example 9 it was 1:0.1:1. The 28-day compressive strength of the dry-mixed mortar obtained in Examples 6-8 was higher than that in Examples 1 and 9. This indicates that when the mass ratio of polypropylene fiber, aminosilane coupling agent, and 2,5-disulfonylbenzaldehyde is 1:0.1:0.3~0.8, the compressive strength of dry-mixed mortar can be further improved.

[0074] The dry-mixed mortar obtained in Example 1 was mixed with water at a water-cement ratio (mass ratio of water to dry-mixed mortar) of 0.15, and the water retention rate, appearance, frost resistance, 28-day compressive strength, setting time, and 2-hour consistency loss rate were tested. The test results are recorded in Table 2.

[0075] Table 2 Properties of Dry-Mixed Mortar

[0076]

[0077] As can be seen from Table 2, the dry-mixed mortar provided by the present invention meets the requirements of GB / T 25181-2019 "Premixed Mortar" in terms of the tested items.

[0078] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A compression-resistant dry-mix mortar, characterized in that The components include the following parts by weight: 40-50 parts cement, 25-35 parts sand, 10-15 parts glass powder, 1-5 parts stone powder, 1-2 parts redispersible latex powder, 1-3 parts modified polypropylene fiber, 0.5-1.5 parts thickener, 5-10 parts expanding agent, and 1-2 parts water-reducing agent. The modified polypropylene fiber is a polypropylene fiber that has been modified with an aminosilane coupling agent and then modified with 2,5-disulfonylbenzaldehyde; the aminosilane coupling agent includes one or both of KH-550 and KH-602. The method for preparing the modified polypropylene fiber includes the following steps: S1. Disperse polypropylene fibers in water, add aminosilane coupling agent, and modify them to obtain aminosilane coupling agent modified polypropylene fibers. S2. The aminosilane coupling agent modified polypropylene fiber is mixed with 2,5-disulfonylbenzaldehyde and solvent, and reacted to obtain modified polypropylene fiber; the reaction temperature in S2 is 120~130℃, and the time is 2~4h.

2. A compression-resistant dry-mix mortar according to claim 1, characterized in that The raw materials for the modified polypropylene fiber include polypropylene fiber, aminosilane coupling agent, and 2,5-disulfonylbenzaldehyde in a mass ratio of 1:0.1:0.3~0.

8.

3. A compression-resistant dry-mix mortar according to claim 1, characterized in that The modification temperature in S1 is 55~65℃, and the modification time is 2~4h.

4. The compressive strength dry-mixed mortar according to claim 1, characterized in that, The mass ratio of glass powder to stone powder is 4:

1.

5. The compressive-resistant dry-mixed mortar according to claim 1, characterized in that, The thickener includes one or both of methyl hydroxyethyl cellulose ether and methyl hydroxypropyl cellulose ether.

6. The compressive strength dry-mixed mortar according to claim 1, characterized in that, The water-reducing agent includes one or two of naphthalene-based water-reducing agents and polycarboxylate water-reducing agents.

7. A method for preparing a compressive-resistant dry-mixed mortar according to any one of claims 1 to 6, characterized in that, The components in the specified mass fractions are mixed evenly to obtain dry-mixed mortar.

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