Environmentally friendly waste tire particle modified premixed mortar and preparation method thereof

Abstract

The invention relates to the field of mortar, and discloses an environmentally friendly premixed mortar modified by waste tire particles and a preparation method thereof. The environmentally friendly premixed mortar modified by waste tire particles comprises the following raw materials in parts by weight: 350-420 parts of cement, 100-150 parts of fly ash, 150-220 parts of modified waste tire particles, 10-25 parts of modified carbon nanotubes, 500-700 parts of fine aggregate, 4-7 parts of water reducing agent, 15-20 parts of early strength agent, 2-5 parts of photoinitiator, 1-3 parts of defoaming agent, 1-2 parts of water reducing agent, 1-2 parts of early strength agent, 2-3 parts of water reducing agent, 1-2 parts of early strength agent, 2-3 parts of early strength ... parts, 0.4-1 parts of thickener, and 190-275 parts of deionized water; the modified waste tire particles are prepared by introducing multiple cross-linking sites on the surface of the waste tire particles using semi-closed isophorone diisocyanate; the modified carbon nanotubes are prepared by in-situ self-polymerization of dopamine to form polydopamine, then in-situ growth of nano-silica, and further introduction of fluorine-containing long chains and mercapto groups. The present invention imparts excellent mechanical strength and anti-seepage performance to the mortar through the addition of modified waste tire particles and modified carbon nanotubes.

Description

Technical Field

[0001] The invention belongs to the technical field of mortar, and in particular relates to an environmentally friendly waste tire particle modified premixed mortar and a preparation method thereof. Background Art

[0002] As a kind of industrial waste, the amount of waste tires is increasing year by year. The piles of waste tires not only occupy land, but also pollute the environment. Therefore, the treatment and reuse of waste tires has become one of the problems that countries around the world need to solve urgently. Studies have shown that crushing waste tires into rubber particles and adding them to cement-based materials can not only improve the toughness of cement-based materials, but also make cement-based materials have excellent properties such as sound insulation, heat insulation, shock absorption, high energy absorption and good durability, which effectively utilizes waste resources.

[0003] With the increase of the amount of waste tire particles, the mechanical strength of cement-based materials has been reduced to varying degrees, especially the compressive strength has been greatly reduced, and this strength weakening effect cannot be improved by simply changing its crushing method, shape and size, and particle grading. The existing technology achieves the purpose of improving and strengthening cement-based materials by mixing fibers as reinforcing materials. However, there are both advantages and disadvantages to adding fibers as a reinforcing material to cement-based materials. Within a reasonable dosage range, the addition of fibers can enhance the mechanical strength of cement-based materials to a certain extent, but mainly enhances its tensile strength, while the improvement of compressive strength is almost negligible, and sometimes it will reduce it, and has a greater impact on its fluidity and workability.

[0004] In addition, cement hydration will produce a large number of hydrophilic hydroxyl groups, which will also cause a large number of tiny pores or defects on the surface and inside of cement-based materials, making cement-based materials more hydrophilic. - and SO4 -2 Corrosive ions can easily penetrate into cement-based materials through tiny pores with the help of water as a carrier, accelerating the occurrence of corrosion. In order to extend the service life of cement-based materials and improve the durability of cement-based materials, it is necessary to enhance the ability of cement-based materials to resist the invasion of water molecules. Summary of the invention

[0005] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide an environmentally friendly waste tire particle modified premixed mortar and a preparation method thereof, by adding modified waste tire particles and modified carbon nanotubes, the mortar is endowed with excellent mechanical strength and anti-permeability properties.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] An environmentally friendly waste tire particle modified premixed mortar comprises the following raw materials in parts by weight: 350-420 parts of cement, 100-150 parts of fly ash, 150-220 parts of modified waste tire particles, 10-25 parts of modified carbon nanotubes, 500-700 parts of fine aggregate, 4-7 parts of water reducing agent, 15-20 parts of early strength agent, 2-5 parts of photoinitiator, 1-3 parts of defoaming agent, 0.4-1 parts of thickener, and 190-275 parts of deionized water;

[0008] The modified waste tire particles are prepared by pretreating the waste tire particles with sodium hydroxide, and then introducing multiple cross-linking sites on the surface of the waste tire particles with semi-closed isophorone diisocyanate, wherein the semi-closed isophorone diisocyanate is prepared by grafting isophorone diisocyanate with pentaerythritol triacrylate through a chemical reaction; the modified carbon nanotubes are prepared by in-situ self-polymerization of dopamine on the surface of the carbon nanotubes to form polydopamine, and then in-situ growth of nano silicon dioxide through a sol-gel method, and further grafting 1H, 1H, 2H, 2H-perfluoroheptadecantrimethyloxysilane and γ-mercaptopropyltrimethoxysilane.

[0009] Preferably, the cement is any one of P·O42.5 ordinary Portland cement and P·O52.5 ordinary Portland cement; and the fine aggregate is river sand with a fineness modulus between 2.4 and 2.8.

[0010] Preferably, the water reducer is a polycarboxylate water reducer; the early strength agent is calcium chloride; the photoinitiator is benzoin dimethyl ether; the defoamer is tributyl phosphate; and the thickener is one or more combinations of hydroxymethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose.

[0011] Preferably, the method for preparing the modified waste tire particles comprises the following steps:

[0012] A. Soak waste tire particles in a sodium hydroxide solution for 2-3 hours, then rinse with deionized water until the pH value is 6.5-7.0, filter and dry to constant weight to prepare pretreated waste tire particles;

[0013] B. Put isophorone diisocyanate in a reactor, add pentaerythritol triacrylate, dibutyltin dilaurate and ethyl acetate, stir evenly, and react at 40-60° C. for 3-5 hours to prepare semi-blocked isophorone diisocyanate;

[0014] C. Pretreated waste tire particles are ultrasonically dispersed in ethyl acetate, heated to 60-75°C, and semi-closed isophorone diisocyanate, dibutyltin dilaurate and p-hydroxyanisole are added and stirred for reaction for 6-8 hours. After the reaction is completed, the particles are filtered, washed and dried to obtain modified waste tire particles.

[0015] Preferably, in step B, the mass ratio of isophorone diisocyanate to pentaerythritol triacrylate is 1:1.31-1.34.

[0016] Preferably, in step C, the mass ratio of the pretreated waste tire particles to the semi-blocked isophorone diisocyanate is 1:2-2.6.

[0017] Preferably, the particle size of the waste tire particles is 0.1-5 mm.

[0018] Preferably, the method for preparing the modified carbon nanotubes comprises the following steps:

[0019] (1) Add carbon nanotubes to a Tris-HCl buffer solution with a pH value of 8.0 to 8.5, disperse them evenly by ultrasonication, then add a mixed solution of dopamine and deionized water, stir and react for 3 to 5 hours, wash with ethanol and deionized water after the reaction is completed, and then disperse the product in anhydrous ethanol to obtain component 1;

[0020] (2) Add ammonia water to component 1, ultrasonically treat for 0.5 to 1 h, then stir at 25 to 40 °C, add ethyl orthosilicate, 1H, 1H, 2H, 2H-perfluoroheptadecantrimethyloxysilane and γ-mercaptopropyltrimethoxysilane and react for 7 to 9 h to prepare modified carbon nanotubes.

[0021] The preparation method of the environmentally friendly waste tire particle modified premixed mortar as described above comprises the following steps: cement, fly ash, modified waste tire particles, modified carbon nanotubes, fine aggregate, water reducer, early strength agent, photoinitiator, defoamer, thickener and deionized water are uniformly mixed according to weight to prepare the environmentally friendly waste tire particle modified premixed mortar.

[0022] Beneficial effects of the present invention:

[0023] The invention uses sodium hydroxide solution to pretreat waste tire particles so that the surfaces of the waste tire particles are rich in hydroxyl groups. At the same time, the invention uses isophorone diisocyanate and pentaerythritol triacrylate to undergo a grafting reaction so that an isocyanate group in the isophorone diisocyanate structure with high reaction activity and directly connected to a cyclohexane ring reacts with a hydroxyl group in the pentaerythritol triacrylate structure to prepare semi-closed isophorone diisocyanate. Then, another isocyanate group in the semi-closed isophorone diisocyanate structure reacts with a hydroxyl group on the surface of the waste tire particles, thereby introducing a plurality of double bond groups on the surface of the waste tire particles, providing a large number of cross-linking sites, and preparing modified waste tire particles.

[0024] The invention uses dopamine to perform in-situ self-polymerization on the surface of carbon nanotubes to form polydopamine, then in-situ grows nano-silica by a sol-gel method, and condenses the silanol groups in the structures of 1H, 1H, 2H, 2H-perfluoroheptadecanetrimethyloxysilane and γ-mercaptopropyltrimethoxysilane with the hydroxyl groups on the surface of nano-silica to prepare modified carbon nanotubes, thereby introducing fluorine-containing long chains and mercapto groups on the surface of modified carbon nanotubes. The introduction of fluorine-containing long chains improves the hydrophobicity of the material and enhances the anti-permeability performance. The mercapto groups react with the photoinitiator to form a modified carbon nanotube. Under the action of the agent, a thiol-ene click reaction occurs with the modified waste tire particles to form a heavily cross-linked network, which connects the cement hydrates together, improves the density of the cement-based material, and enhances the ability of the cement-based material to resist the invasion of water molecules. At the same time, it can enhance the durability and mechanical stability of the cement-based material, so that the external force can be dispersed along the network structure, thereby improving the mechanical strength of the cement-based material. In addition, the addition of modified carbon nanotubes can effectively reduce the internal pores of the cement-based material and improve its microstructure, thereby significantly enhancing the density and mechanical strength. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1 A method for preparing modified waste tire particles comprises the following steps:

[0027] A. Soak waste tire particles in a 1 mol / L sodium hydroxide solution for 2 h, then rinse with deionized water until the pH value is 7.0, filter and dry to constant weight to prepare pretreated waste tire particles;

[0028] B. Take 25.00 g of isophorone diisocyanate in a reactor, add 33.16 g of pentaerythritol triacrylate, 0.20 g of dibutyltin dilaurate and 50 mL of ethyl acetate, stir evenly, and react at 55 ° C for 4 hours to prepare semi-blocked isophorone diisocyanate;

[0029] C. Take 9.00g of pretreated waste tire particles and ultrasonically disperse them in 100mL of ethyl acetate. Heat the temperature to 70°C, add 21.70g of semi-blocked isophorone diisocyanate, 0.03g of dibutyltin dilaurate and 0.02g of p-hydroxyanisole, stir and react for 8h. After the reaction is completed, filter, wash and dry to prepare modified waste tire particles.

[0030] Example 2 A method for preparing modified carbon nanotubes comprises the following steps:

[0031] (1) A Tris-HCl buffer solution with a pH value of 8.5 was prepared using 0.1 mol / L Tris solution and 0.1 mol / L hydrochloric acid solution, 1 g of carbon nanotubes was added to 250 mL of Tris-HCl buffer solution, and ultrasonic dispersion was performed uniformly. Then, a mixed solution of 0.5 g of dopamine and 2 mL of deionized water was added, and the mixture was stirred for reaction for 5 h. After the reaction was completed, the mixture was washed with ethanol and deionized water, and then the product was dispersed in 40 mL of anhydrous ethanol to obtain component 1.

[0032] (2) Add 2 mL of aqueous ammonia to component 1, ultrasonically treat for 0.5 h, and then stir at 30 °C. Add 2.1 wt% of ethyl orthosilicate, 0.01 mL of 1H, 1H, 2H, 2H-perfluoroheptadecantrimethylsilane and 0.02 mL of γ-mercaptopropyltrimethoxysilane and react for 8 h to prepare modified carbon nanotubes.

[0033] Example 3 An environmentally friendly waste tire particle modified premixed mortar comprises the following raw materials in parts by weight:

[0034] 355 parts of PO42.5 grade ordinary Portland cement, 100 parts of first-grade fly ash, 154 parts of modified waste tire particles prepared in Example 1, 10 parts of modified carbon nanotubes prepared in Example 2, 515 parts of river sand with a fineness modulus of 2.5, 4 parts of polycarboxylic acid water reducer, 15 parts of early strength agent calcium chloride, 2 parts of photoinitiator benzoin dimethyl ether, 1 part of defoaming agent tributyl phosphate, 0.4 parts of thickener hydroxymethyl cellulose, and 195 parts of deionized water.

[0035] The method for preparing the environmentally friendly waste tire particle modified premixed mortar comprises the following steps:

[0036] The environmentally friendly waste tire particle modified premixed mortar is prepared by uniformly mixing P·O42.5 grade ordinary Portland cement, first-grade fly ash, modified waste tire particles, modified carbon nanotubes, river sand with a fineness modulus of 2.5, polycarboxylic acid water reducer, early strength agent calcium chloride, photoinitiator benzoin dimethyl ether, defoamer tributyl phosphate, thickener hydroxymethyl cellulose and deionized water according to weight parts.

[0037] Example 4 An environmentally friendly waste tire particle modified premixed mortar comprises the following raw materials in parts by weight:

[0038] 388 parts of PO42.5 grade ordinary Portland cement, 125 parts of first-grade fly ash, 174 parts of modified waste tire particles prepared in Example 1, 17 parts of modified carbon nanotubes prepared in Example 2, 600 parts of river sand with a fineness modulus of 2.5, 5 parts of polycarboxylic acid water reducer, 17 parts of early strength agent calcium chloride, 3 parts of photoinitiator benzoin dimethyl ether, 2 parts of defoaming agent tributyl phosphate, 0.7 parts of thickener hydroxymethyl cellulose, and 225 parts of deionized water.

[0039] The preparation method of the above-mentioned environmentally friendly waste tire particle modified premixed mortar is the same as that in Example 3.

[0040] Example 5 An environmentally friendly waste tire particle modified premixed mortar comprises the following raw materials in parts by weight:

[0041] 417 parts of PO42.5 grade ordinary Portland cement, 150 parts of first-grade fly ash, 220 parts of modified waste tire particles prepared in Example 1, 24 parts of modified carbon nanotubes prepared in Example 2, 698 parts of river sand with a fineness modulus of 2.5, 7 parts of polycarboxylic acid water reducer, 20 parts of early strength agent calcium chloride, 5 parts of photoinitiator benzoin dimethyl ether, 3 parts of defoaming agent tributyl phosphate, 1 part of thickener hydroxymethyl cellulose, and 270 parts of deionized water.

[0042] The preparation method of the above-mentioned environmentally friendly waste tire particle modified premixed mortar is the same as that in Example 3.

[0043] Comparative Example 1 An environmentally friendly waste tire particle modified premixed mortar comprises the following raw materials in parts by weight:

[0044] 417 parts of PO42.5 grade ordinary Portland cement, 150 parts of first-grade fly ash, 220 parts of waste tire particles, 24 parts of modified carbon nanotubes prepared in Example 2, 698 parts of river sand with a fineness modulus of 2.5, 7 parts of polycarboxylic acid water reducer, 20 parts of early strength agent calcium chloride, 5 parts of photoinitiator benzoin dimethyl ether, 3 parts of defoaming agent tributyl phosphate, 1 part of thickener hydroxymethyl cellulose, and 270 parts of deionized water.

[0045] The preparation method of the above-mentioned environmentally friendly waste tire particle modified premixed mortar is the same as that in Example 3.

[0046] Comparative Example 2 An environmentally friendly waste tire particle modified premixed mortar comprises the following raw materials in parts by weight:

[0047] 417 parts of PO42.5 grade ordinary Portland cement, 150 parts of first-grade fly ash, 220 parts of modified waste tire particles prepared in Example 1, 24 parts of carbon nanotubes, 698 parts of river sand with a fineness modulus of 2.5, 7 parts of polycarboxylic acid water reducer, 20 parts of early strength agent calcium chloride, 5 parts of photoinitiator benzoin dimethyl ether, 3 parts of defoaming agent tributyl phosphate, 1 part of thickener hydroxymethyl cellulose, and 270 parts of deionized water.

[0048] The preparation method of the above-mentioned environmentally friendly waste tire particle modified premixed mortar is the same as that in Example 3.

[0049] Performance Testing

[0050] The environmentally friendly waste tire particle modified premixed mortar prepared in Examples 3-5 and Comparative Examples 1-2 was subjected to performance testing: the compressive and flexural strengths were tested with reference to the national standard GB / T 17671-2021 "Test Method for Cement Mortar Strength"; the anti-penetration performance was tested by making cement mortar specimens according to JGJ / T 70-2009 "Standard for Test Method for Basic Performance of Building Mortar". When the specimens were cured to 28 days old, they were taken out of the curing box. After their surfaces were dry, their sides were sealed with a sealing material made of a mixture of paraffin and rosin melted and stirred. After the specimens were sealed, a penetration test was carried out in a mortar permeameter. The mortar penetration pressure calculation formula was: P=H-0.1, where P-mortar penetration pressure (MPa); H-pressure (MPa) at which 3 of the 6 penetration specimens began to seep water. The data results are shown in Table 1.

[0051]

[0052] It can be seen from the data in Table 1 that the mortars prepared in Examples 3-5 of the present invention have high compressive strength and flexural strength, and good impermeability. In Comparative Example 1, the waste tire particles were not modified, and the measured compressive strength, flexural strength, penetration pressure and penetration time were lower than those of Examples 3-5, indicating that the mechanical strength and impermeability of the material can be improved by modifying the waste tire particles. In Comparative Example 2, the carbon nanotubes were not modified, and the measured mechanical strength and impermeability were lower than those of Examples 3-5, because the components did not contain nano-silicon dioxide, and no fluorine-containing long chains and mercapto groups were introduced, resulting in reduced performance.

[0053] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. An environmentally friendly waste tire particle modified premixed mortar, characterized in that: The invention comprises the following raw materials in parts by weight: 350-420 parts of cement, 100-150 parts of fly ash, 150-220 parts of modified waste tire particles, 10-25 parts of modified carbon nanotubes, 500-700 parts of fine aggregate, 4-7 parts of water reducing agent, 15-20 parts of early strength agent, 2-5 parts of photoinitiator, 1-3 parts of defoaming agent, 0.4-1 parts of thickener, and 190-275 parts of deionized water; The modified waste tire particles are prepared by pretreating the waste tire particles with sodium hydroxide, and then introducing multiple cross-linking sites on the surface of the waste tire particles with semi-closed isophorone diisocyanate, wherein the semi-closed isophorone diisocyanate is prepared by grafting isophorone diisocyanate with pentaerythritol triacrylate by chemical reaction; the modified carbon nanotubes are prepared by in-situ self-polymerization of dopamine on the surface of carbon nanotubes to form polydopamine, and then in-situ growth of nano-silica by a sol-gel method, and further grafting 1H, 1H, 2H, 2H-perfluoroheptadecantrimethyloxysilane and γ-mercaptopropyltrimethoxysilane; The preparation method of the modified waste tire particles comprises the following steps: A. Soak waste tire particles in a sodium hydroxide solution for 2-3 hours, then rinse with deionized water until the pH value is 6.5-7.0, filter and dry to constant weight to prepare pretreated waste tire particles; B. Put isophorone diisocyanate in a reactor, add pentaerythritol triacrylate, dibutyltin dilaurate and ethyl acetate, stir evenly, and react at 40-60° C. for 3-5 hours to prepare semi-blocked isophorone diisocyanate; C. Pretreated waste tire particles are ultrasonically dispersed in ethyl acetate, the temperature is raised to 60-75°C, semi-closed isophorone diisocyanate, dibutyltin dilaurate and p-hydroxyanisole are added, stirred and reacted for 6-8 hours, and after the reaction is completed, the modified waste tire particles are prepared by filtration, washing and drying; The preparation method of the modified carbon nanotubes comprises the following steps: (1) Add carbon nanotubes to a Tris-HCl buffer solution with a pH value of 8.0 to 8.5, disperse them evenly by ultrasonication, then add a mixed solution of dopamine and deionized water, stir and react for 3 to 5 hours, wash with ethanol and deionized water after the reaction is completed, and then disperse the product in anhydrous ethanol to obtain component 1; (2) Add ammonia water to component 1, ultrasonically treat for 0.5 to 1 h, then stir at 25 to 40 °C, add ethyl orthosilicate, 1H, 1H, 2H, 2H-perfluoroheptadecantrimethyloxysilane and γ-mercaptopropyltrimethoxysilane and react for 7 to 9 h to prepare modified carbon nanotubes.

2. The environmentally friendly waste tire particle modified premixed mortar according to claim 1, characterized in that: The cement is any one of P·O42.5 ordinary Portland cement and P·O52.5 ordinary Portland cement; the fine aggregate is river sand with a fineness modulus between 2.4 and 2.

8.

3. The environmentally friendly waste tire particle modified premixed mortar according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer; the early strength agent is calcium chloride; the photoinitiator is benzoin dimethyl ether; the defoamer is tributyl phosphate; and the thickener is one or more combinations of hydroxymethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose.

4. The environmentally friendly waste tire particle modified premixed mortar according to claim 1, characterized in that: The mass ratio of isophorone diisocyanate to pentaerythritol triacrylate in step B is 1:1.31-1.

34.

5. The environmentally friendly waste tire particle modified premixed mortar according to claim 1, characterized in that: In the step C, the mass ratio of the pretreated waste tire particles to the semi-blocked isophorone diisocyanate is 1:2-2.

6.

6. The environmentally friendly waste tire particle modified premixed mortar according to claim 1, characterized in that: The particle size of the waste tire particles is 0.1-5 mm.

7. The method for preparing the environmentally friendly waste tire particle modified premixed mortar according to any one of claims 1 to 6, characterized in that: The following steps are involved: Cement, fly ash, modified waste tire particles, modified carbon nanotubes, fine aggregate, water reducer, early strength agent, photoinitiator, defoamer, thickener and deionized water are uniformly mixed according to weight to prepare environmentally friendly waste tire particle modified premixed mortar.

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