An organic fiber-reinforced anti-cracking mortar and a method for preparing the same

Abstract

The application relates to the technical field of building materials, and discloses an organic fiber reinforced anti-cracking mortar and a preparation method thereof. Cement, fine aggregate, polycarboxylate superplasticizer, calcium sulfoaluminate, hydroxypropyl methylcellulose and modified fatty acid are added into a stirrer, and stirred for 4-6 minutes; then, epoxy nano-silicon dioxide and silane modified polyester fiber are added into the stirrer, and stirred for 2-4 minutes; then, water is added into the stirrer, and stirred for 5-10 minutes; and finally, the organic fiber reinforced anti-cracking mortar is obtained. The mortar has good anti-cracking and mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to an organic fiber reinforced anti-cracking mortar and a preparation method thereof. BACKGROUND

[0002] In the field of building materials, mortar is an important building material widely used in construction engineering. However, traditional mortar has certain deficiencies in terms of crack resistance and durability, especially when facing environmental factors such as temperature changes and humidity fluctuations, which can easily cause cracks, affecting the service life and safety of buildings. In recent years, the application of fiber reinforced materials in building materials has gradually attracted attention. By adding fiber materials to mortar, the crack resistance and toughness of the mortar can be effectively improved. For example, patent CN108947376 cement mortar and a preparation method thereof, the mechanical properties of the mortar, the compressive and flexural strength are significantly improved, but its crack resistance needs to be improved. SUMMARY

[0003] (I) Technical problems to be solved

[0004] In view of the deficiencies of the prior art, the present application provides an organic fiber reinforced anti-cracking mortar and a preparation method thereof, which has good crack resistance and mechanical properties.

[0005] (II) Technical solutions

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: an organic fiber reinforced anti-cracking mortar, comprising the following components by weight: 85-110 parts by weight of cement, 45-70 parts by weight of fine aggregate, 0.2-0.3 parts by weight of polycarboxylic acid water reducer, 0.1-0.3 parts by weight of hydroxypropyl methylcellulose, 1-2 parts by weight of calcium sulfoaluminate, 0.1-0.2 parts by weight of epoxy nano-silicon dioxide, 0.2-0.4 parts by weight of modified fatty acid, 0.5-0.6 parts by weight of silane modified polyester fiber, and 50-60 parts by weight of water.

[0007] Further, the preparation method of the modified fatty acid is:

[0008] Step one: 2.1-2.5g of 3-dimethylamino-1-propylamine and 6-10mL of phosphoric acid are added to a reactor, then 4.01-4.12g of long-chain fatty acid (n=12) is added, and the reaction is carried out at 140-150℃, then 0.05mol / L NaOH solution is added, the pH of the reaction solution is adjusted to 7, and after reaction, it is distilled under reduced pressure to obtain intermediate 1;

[0009] Step two: add 1,3-dibromo-2,2-dihydroxymethylpropane and intermediate 1 into isopropyl alcohol solvent, reflux at 80-85℃ for 20-24h, after the reaction is completed, remove the solvent by distillation under reduced pressure, wash with acetone, and obtain intermediate 2;

[0010] Step three: add intermediate 2 and 4-aminobutyric acid into 40-55mL of N,N-dimethylformamide solvent, stir the mixture, continue to add p-toluenesulfonic acid catalyst, react at 75-85℃, after the reaction is completed, distill under reduced pressure, filter and wash, and obtain modified fatty acid.

[0011] Further, the reaction time in step one is 8-10h.

[0012] Further, the amount of isopropyl alcohol, 1,3-dibromo-2,2-dihydroxymethylpropane, and intermediate 1 in step two is 40-55mL:2.41-2.55g:4.33-5.14g.

[0013] Further, the mass ratio of intermediate 2, 4-aminobutyric acid, and p-toluenesulfonic acid catalyst in step three is 3.11-3.45g:2.21-2.35g:0.01-0.02g.

[0014] Further, the reaction time in step three is 6-8h.

[0015] Further, the preparation method of the silane-modified polyester fiber is:

[0016] S1. Dip 2-3 parts by weight of polyester fiber into a 3% NaOH solution, react at 60-75℃ for 10-15min, then wash with deionized water until neutral, and dry;

[0017] S2. Add 5-10 parts by weight of KH-550 silane coupling agent to 60mL of ethanol / water mixed solvent (volume ratio 8:2), adjust the pH to 4-5 with acetic acid, and stir for 20-30min.

[0018] S3. Add the treated polyester fiber in S1 to the silane coupling agent solution in S2, immerse, and react at 60℃ for 1h to obtain silane-modified polyester fiber.

[0019] Further, the preparation method of the organic fiber-reinforced anti-cracking mortar is: add cement, fine aggregate, polycarboxylate superplasticizer, calcium sulfoaluminate, hydroxypropyl methyl cellulose, and modified fatty acid into a blender, stir for 4-6min, then add epoxy nano-silica and silane-modified polyester fiber, continue to stir for 2-4min, then add water, and stir for 5-10min to obtain the organic fiber-reinforced anti-cracking mortar.

[0020] (III) Beneficial technical effects

[0021] By adding epoxy nano-silica and silane modified polyester fiber and modified fatty acid in the mortar, the crack resistance of the mortar is significantly improved. The epoxy nano-silica can fill the small pores in the mortar, reduce the formation and expansion of cracks, and thus enhance the overall crack resistance of the mortar. The silane modified polyester fiber can also improve the crack resistance and compressive strength of the mortar. The addition of long-chain alkane in the modified fatty acid can improve the flexibility of the mortar, so that it is not easy to crack when subjected to external force. The quaternary ammonium salt group in the modified fatty acid can reduce the water absorption of the mortar and improve its durability. During the mixing process, the epoxy group of the epoxy nano-silica will undergo ring-opening reaction with the amino group in the modified fatty acid, and then the silane modified polyester fiber will be wound, forming a three-dimensional network structure between each other. In the mortar, this network structure can tightly combine each component together, increasing the interaction force inside the material. When the mortar is subjected to external force, the molecular network can effectively disperse and transfer stress, preventing local damage caused by stress concentration, thereby improving the mechanical properties of the mortar. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the reaction formula of the modified fatty acid of Example 1.

[0023] Figure 2 is the nuclear magnetic resonance spectrum of the modified fatty acid of Example 1. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application is described clearly and completely. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] In order to better understand the above technical scheme, the above technical scheme will be described in detail below in combination with the drawings and specific embodiments in the specification.

[0026] Preparation of epoxy nano-silica: Refer to the literature "Nano-silica modified by silane coupling agent KH-560", a certain amount of nano-silica is taken and added into 20 mL of toluene, and ultrasonic dispersion is performed at room temperature for 30 min by using a KQ-300E ultrasonic cleaner (300 W) to obtain a uniform suspension, then silane coupling agent KH-560 is added and ultrasonic dispersion is continued for 3-4 min, and then the mixture is transferred into a 100 mL four-necked flask equipped with a reflux condenser and an electric stirring device, and stirring reaction is performed at a set oil bath temperature, and after reaction, the slurry is separated by centrifugation at room temperature at a speed of 12000 r / min by using a CT15RT table centrifuge to obtain epoxy nano-silica.

[0027] The length of the silane-modified polyester fiber in the present application is 8 mm.

[0028] Example 1

[0029] Step one: 2.1 g of 3-dimethylamino-1-propanamine and 6 mL of phosphoric acid are added to a reactor, then 4.01 g of long-chain fatty acid (n=12) is added, and reaction is performed at 140℃ for 8 h, then a 0.05 mol / L NaOH solution is added to adjust the pH of the reaction solution to 7, and after reaction, distillation is performed under reduced pressure to obtain intermediate 1;

[0030] Step two: 2.41 g of 1,3-dibromo-2,2-dimethylol propane and 4.33 g of intermediate 1 are added to 40 mL of isopropyl alcohol solvent, and reaction is performed at 80℃ under reflux for 20 h, and after completion, the solvent is removed by distillation under reduced pressure, and then acetone washing is performed to obtain intermediate 2;

[0031] Step three: 3.11 g of intermediate 2 and 2.21 g of 4-aminobutyric acid are added to 40 mL of N,N-dimethylformamide solvent, and stirring is performed, then 0.01 g of p-toluenesulfonic acid catalyst is added, and reaction is performed at 75℃ for 6 h, and after completion, distillation is performed under reduced pressure, and then filtration and washing are performed to obtain the modified fatty acid.

[0032] The preparation method of the silane-modified polyester fiber is as follows:

[0033] S1. 2 parts by weight of polyester fiber are immersed in a 3% NaOH solution, and reaction is performed at 60℃ for 10 min, and then the polyester fiber is washed to neutral with deionized water and dried;

[0034] S2. 5 parts by weight of KH-550 silane coupling agent is added to 60 mL of an ethanol / water mixed solvent (volume ratio 8:2), and the pH is adjusted to 4 with acetic acid, and stirring is performed for 20 min;

[0035] S3. The polyester fiber treated in S1 is added to the silane coupling agent solution in S2, and immersion is performed, and reaction is performed at 60℃ for 1 h to obtain the silane-modified polyester fiber.

[0036] The preparation method of the organic fiber reinforced anti-cracking mortar is: 85 parts by weight of cement, 45 parts by weight of fine aggregate, 0.2 parts by weight of polycarboxylic acid water reducer, 1 part by weight of calcium sulfoaluminate, 0.1 part by weight of hydroxypropyl methyl cellulose, 0.2 parts by weight of modified fatty acid are added into a blender, stirred for 4 min, then 0.1 parts by weight of epoxy nano silicon dioxide, 0.5 parts by weight of silane modified polyester fiber are added, continue to stir for 2 min, then add 50 parts by weight of water, stir for 5 min, to obtain the organic fiber reinforced anti-cracking mortar.

[0037] Example 2

[0038] Step one: 2.5g of 3-dimethylamino-1-propanamine and 10mL of phosphoric acid are added to the reactor, then 4.12g of long-chain fatty acid (n=12) is added, reacted at 150℃ for 10h, then 0.05mol / L NaOH solution is added to adjust the pH of the reaction solution to 7, after reaction, reduced pressure distillation, to obtain intermediate 1;

[0039] Step two: 2.55g of 1,3-dibromo-2,2-dimethylol propane and 5.14g of intermediate 1 are added to 55mL of isopropyl alcohol solvent, refluxed at 85℃ for 24h, after completion, the solvent is removed by reduced pressure distillation, washed with acetone to obtain intermediate 2;

[0040] Step three: 3.45g of intermediate 2 and 2.35g of 4-aminobutyric acid are added to 55mL of N,N-dimethylformamide solvent, stirred and mixed, then 0.02g of p-toluenesulfonic acid catalyst is added, reacted at 85℃ for 8h, after completion, distilled under reduced pressure, filtered and washed to obtain the modified fatty acid.

[0041] The preparation method of the silane modified polyester fiber is:

[0042] S1. 3 parts by weight of polyester fiber are immersed in a 3% NaOH solution, reacted at 75℃ for 15min, then washed with deionized water until neutral, and dried;

[0043] S2. 10 parts by weight of KH-550 silane coupling agent is added to 60mL of ethanol / water mixed solvent (volume ratio 8:2), the pH is adjusted to 5 with acetic acid, and stirred for 30min;

[0044] S3. The treated polyester fiber in S1 is added to the silane coupling agent solution in S2 for immersion, reacted at 60℃ for 1h to obtain the silane modified polyester fiber.

[0045] The preparation method of the organic fiber reinforced anti-cracking mortar is as follows: 110 parts by weight of cement, 70 parts by weight of fine aggregate, 0.3 parts by weight of polycarboxylate superplasticizer, 2 parts by weight of calcium sulfoaluminate, 0.3 parts by weight of hydroxypropyl methylcellulose, and 0.4 parts by weight of modified fatty acid are added into a stirrer and stirred for 6 min, then 0.2 parts by weight of epoxy nano-silicon dioxide and 0.6 parts by weight of silane modified polyester fiber are added and stirred for 4 min, and then 60 parts by weight of water is added and stirred for 10 min to obtain the organic fiber reinforced anti-cracking mortar.

[0046] Example 3

[0047] Step one: 2.3g of 3-dimethylamino-1-propylamine and 8mL of phosphoric acid are added to a reactor, then 4.06g of long-chain fatty acid (n=12) is added, and the reaction is carried out at 145℃ for 9h, then 0.05mol / L NaOH solution is added to adjust the pH of the reaction solution to 7, and after reaction, it is distilled under reduced pressure to obtain intermediate 1;

[0048] Step two: 2.48g of 1,3-dibromo-2,2-dihydroxymethyl propane and 4.74g of intermediate 1 are added to 50mL of isopropyl alcohol solvent, and the reaction is carried out at 82℃ for 22h, then the solvent is removed by distillation under reduced pressure, and acetone is used for washing to obtain intermediate 2;

[0049] Step three: 3.28g of intermediate 2 and 2.26g of 4-aminobutyric acid are added to 45mL of N,N-dimethylformamide solvent, stirred and mixed, and then 0.015g of p-toluenesulfonic acid catalyst is added, and the reaction is carried out at 80℃ for 7h, then distilled under reduced pressure, filtered and washed to obtain the modified fatty acid.

[0050] The preparation method of the silane modified polyester fiber is as follows:

[0051] S1. 2 parts by weight of polyester fiber is immersed in a 3% NaOH solution, and the reaction is carried out at 70℃ for 12 min, then washed with deionized water until neutral, and dried;

[0052] S2. 8 parts by weight of KH-550 silane coupling agent is added to 60mL of ethanol / water mixed solvent (volume ratio 8:2), and the pH is adjusted to 4 with acetic acid, and stirred for 25 min;

[0053] S3. The treated polyester fiber in S1 is added to the silane coupling agent solution in S2 for immersion, and the reaction is carried out at 60℃ for 1h to obtain the silane modified polyester fiber.

[0054] The preparation method of the organic fiber reinforced anti-cracking mortar is: 95 parts by weight of cement, 60 parts by weight of fine aggregate, 0.25 parts by weight of polycarboxylate superplasticizer, 1.5 parts by weight of calcium sulfoaluminate, 0.15 parts by weight of hydroxypropyl methylcellulose, 0.3 parts by weight of modified fatty acid are added into a stirrer, stirred for 5 min, then 0.15 parts by weight of epoxy nano-silicon dioxide, 0.55 parts by weight of silane modified polyester fiber are added, continue to stir for 3 min, then add 55 parts by weight of water, stir for 8 min, get the organic fiber reinforced anti-cracking mortar.

[0055] Example 4

[0056] Step one: 2.1g of 3-dimethylamino-1-propylamine and 6mL of phosphoric acid are added to the reactor, then 4.01g of long-chain fatty acid (n=12) is added, reacted at 140℃ for 8h, then 0.05mol / L NaOH solution is added, adjust the pH of the reaction solution to 7, after reaction, reduce pressure distillation, get intermediate 1;

[0057] Step two: 2.41g of 1,3-dibromo-2,2-dimethylol propane and 4.33g of intermediate 1 are added to 40mL of isopropyl alcohol solvent, refluxed at 80℃ for 20h, after the end of the reaction, the solvent is removed by reduced pressure distillation, washed with acetone, get intermediate 2;

[0058] Step three: 3.45g of intermediate 2 and 2.35g of 4-aminobutyric acid are added to 55mL of N,N-dimethylformamide solvent, stir mixed, continue to add 0.02g of p-toluenesulfonic acid catalyst, react at 85℃ for 8h, after the end of the reaction, reduce pressure distillation, filter and wash, get modified fatty acid.

[0059] The preparation method of the silane modified polyester fiber is:

[0060] S1. 2 parts by weight of polyester fiber are immersed in a 3% NaOH solution, reacted at 70℃ for 12min, then washed with deionized water until neutral, dried;

[0061] S2. 8 parts by weight of KH-550 silane coupling agent is added to 60mL of ethanol / water mixed solvent (volume ratio 8:2), adjust the pH to 4 with acetic acid, stir for 25min;

[0062] S3. The treated polyester fiber in S1 is added to the silane coupling agent solution in S2, immersed, reacted at 60℃ for 1h, get the silane modified polyester fiber.

[0063] The preparation method of the organic fiber reinforced anti-cracking mortar is as follows: 95 parts by weight of cement, 60 parts by weight of fine aggregate, 0.25 parts by weight of polycarboxylic acid water reducing agent, 1.5 parts by weight of calcium sulfoaluminate, 0.15 parts by weight of hydroxypropyl methylcellulose, 0.3 parts by weight of modified fatty acid are added into a stirrer, stirred for 5 min, then 0.15 parts by weight of epoxy nano-silica, 0.55 parts by weight of silane modified polyester fiber are added, continue to stir for 3 min, then 55 parts by weight of water is added, and stirred for 8 min to obtain the organic fiber reinforced anti-cracking mortar.

[0064] Comparative Example 1

[0065] The difference between the present comparative example and Example 4 is that no modified fatty acid is added.

[0066] Comparative Example 2

[0067] The difference between the present comparative example and Example 4 is that no silane modified polyester fiber is added.

[0068] Comparative Example 3

[0069] The difference between the present comparative example and Example 4 is that no epoxy nano-silica is added.

[0070] The compressive and flexural strength tests are carried out according to GB / T 17671-1999 "Cement mortar strength test method", and the anti-cracking strength test is carried out according to JC / T 1004-2006 "Ceramic wall and floor tile joint sealant".

[0071] Table 1: Mechanical property test.

[0072]

[0073] As shown in Table 1, the Examples 1-4 of the present application have better compressive and flexural effects compared with Comparative Examples 1-3.

[0074] The anti-cracking performance of the mortar is tested according to the provisions of CECS-13:2009.

[0075] Table 2: Anti-cracking performance test.

[0076] Item Anti-Cracking Grade Example 1 Grade I Example 2 Grade I Example 3 Grade I Example 4 Grade I Comparative Example 1 Grade II Comparative Example 2 Grade II Comparative Example 3 Grade II

[0077] As shown in Table 2, the Examples 1-4 of the present application have better anti-cracking performance compared with Comparative Examples 1-3.

[0078] It should be noted that, in the present document, the terms "comprising", "comprises" or any other variant thereof are intended to cover non-exclusive inclusions, such that processes, methods, articles, or apparatuses that comprise a list of elements are not limited to those elements, but can include other elements not expressly listed or inherent to such processes, methods, articles, or apparatuses. Without further limitation, an element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0079] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

[0080] Those skilled in the art should understand that the above only describes some specific embodiments of the present application, rather than all embodiments.

Claims

1. An organic fiber-reinforced crack-resistant mortar, characterized in that, It comprises the following components by weight: 85-110 parts by weight of cement, 45-70 parts by weight of fine aggregate, 0.2-0.3 parts by weight of polycarboxylate superplasticizer, 0.1-0.3 parts by weight of hydroxypropyl methylcellulose, 1-2 parts by weight of calcium sulfoaluminate, 0.1-0.2 parts by weight of epoxy nano-silica, 0.2-0.4 parts by weight of modified fatty acid, 0.5-0.6 parts by weight of silane-modified polyester fiber, and 50-60 parts by weight of water; The method for preparing the modified fatty acid is as follows: Step 1: Add 2.1-2.5 g of 3-dimethylamino-1-propylamine and 6-10 mL of phosphoric acid to the reactor, then add 4.01-4.12 g of long-chain fatty acid with a total of 12 carbon atoms in the fatty acid molecule. React at 140-150℃, then add 0.05 mol / L NaOH solution to adjust the pH of the reaction solution to 7. After the reaction, distill under reduced pressure to obtain intermediate 1. Step 2: Add 1,3-dibromo-2,2-dihydroxymethylpropane and intermediate 1 to isopropanol solvent, reflux at 80-85℃ for 20-24 h, remove the solvent by vacuum distillation after the reaction, wash with acetone to obtain intermediate 2. Step 3: Add intermediate 2 and 4-aminobutyric acid to 40-55 mL of N,N-dimethylformamide solvent, stir and mix, continue to add p-toluenesulfonic acid catalyst, react at 75-85℃, distill under reduced pressure after the reaction is completed, filter and wash to obtain modified fatty acids; The reaction time in step one is 8-10 hours; In step two, the ratio of isopropanol, 1,3-dibromo-2,2-dimethylolpropane, and intermediate 1 is 40-55 mL: 2.41-2.55 g: 4.33-5.14 g. In step three, the mass ratio of intermediate 2,4-aminobutyric acid and p-toluenesulfonic acid catalyst is 3.11-3.45g: 2.21-2.35g: 0.01-0.02g; The reaction time in step three is 6-8 hours.

2. The organic fiber-reinforced crack-resistant mortar according to claim 1, characterized in that, The method for preparing the silane-modified polyester fiber is as follows: S1. Immerse 2-3 parts by weight of polyester fiber in a 3% NaOH solution and react at 60-75℃ for 10-15 minutes. Then wash with deionized water until neutral and dry. S2. Add 5-10 parts by weight of KH-550 silane coupling agent to 60 mL of ethanol / water mixed solvent. The volume ratio of ethanol to water in the mixed solvent is 8:

2. Adjust the pH to 4-5 with acetic acid and stir for 20-30 min. S3. Add the polyester fiber treated in S1 to the silane coupling agent solution in S2 for impregnation, and react at 60°C for 1 hour to obtain silane-modified polyester fiber.

3. A method for preparing organic fiber-reinforced crack-resistant mortar as described in any one of claims 1-2, characterized in that, The method for preparing the organic fiber reinforced crack-resistant mortar is as follows: cement, fine aggregate, polycarboxylate superplasticizer, calcium sulfoaluminate, hydroxypropyl methylcellulose, and modified fatty acid are added to a mixer and stirred for 4-6 minutes. Then, epoxy nano-silica and silane-modified polyester fibers are added and stirred for another 2-4 minutes. Finally, water is added and stirred for 5-10 minutes to obtain the organic fiber reinforced crack-resistant mortar.

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