CN116102324A - Multistage interpenetrating network modified cement-based composite material and preparation method thereof - Google Patents

Abstract

The invention discloses a multistage interpenetrating network modified cement-based composite material, which comprises the following components in parts by weight: 90-100 parts of cementing material, 1-5 parts of multipolymer monomer, 0.001-0.003 part of cross-linking agent, 0.005-0.015 part of initiator, 0.005-0.04 part of catalyst, 0.01-0.5 part of nano cellulose, 0.15-0.25 part of defoamer, 0.5-1.5 parts of water reducer, 0-1.4 parts of sodium hydroxide and 35-55 parts of mixing water. The invention adopts a multistage interpenetrating network modified cement-based composite material and a preparation method thereof, takes a multi-polymer monomer as a primary network, takes cellulose nanofiber as a secondary network, and forms the multistage interpenetrating network cement-based composite material which is uniformly entangled with a cementing material hydration product through a preparation method of in-situ polymerization and synchronous induction.

Description

Multistage interpenetrating network modified cement-based composite material and preparation method thereof

Technical Field

The invention relates to the technical field of concrete, in particular to a multistage interpenetrating network modified cement-based composite material and a preparation method thereof.

Background

The cement-based material is a brittle material with high compressive strength and low tensile strength, and the toughness and the improvement of the crack resistance of the matrix on a macro scale are known according to a multi-scale characteristic model of the brittle material, and the toughness and the improvement mainly depend on the higher deformability of the microstructure under the action of continuous or impact load. The microstructure of the cement-based material is improved, and the inhibition research of matrix microcracks is developed, so that the method is an effective way for fundamentally realizing the high toughness and high crack resistance of the cement-based material.

In recent years, many students accurately regulate and control the microstructure of a matrix through methods such as fiber modification, polymer modification, nanomaterial modification and the like, and perform collaborative suppression research on cracks under multiple scales by utilizing a multi-element toughening material re-doping method, and have obtained beneficial attempts. However, the traditional crack-resistant toughening method cannot effectively improve the global toughness of the cement matrix due to the agglomeration effect and the phase separation difficulty of the toughening material; in addition, the network uniformity of the multi-scale toughening material is still to be optimized, the mechanism is not clear, and the multi-scale regulation and control efficiency in the structural defect and crack propagation still faces a great challenge.

Therefore, how to perfect the integrated design of the multistage toughening network, realize the uniform toughening of the cement-based material with multiple dimensions and full matrix, and further improve the sensitivity of the toughening network to microcracks is still a bottleneck problem to be broken through.

Disclosure of Invention

The invention aims to provide a multistage interpenetrating network modified cement-based composite material and a preparation method thereof, which solve the problems of poor integrity and low toughening efficiency caused by poor phase separation and agglomeration effects of the traditional toughening material.

In order to achieve the purpose, the invention provides a multistage interpenetrating network modified cement-based composite material, which comprises the following components in parts by weight: 90-100 parts of cementing material, 1-5 parts of multipolymer monomer, 0.001-0.003 part of cross-linking agent, 0.005-0.015 part of initiator, 0.005-0.04 part of catalyst, 0.01-0.5 part of nano cellulose, 0.15-0.25 part of defoamer, 0.5-1.5 parts of water reducer, 0-1.4 parts of sodium hydroxide and 35-55 parts of mixing water.

Preferably, the multipolymer monomer is one or more of acrylic monomer, 2-acrylic amide-2-methylpropanesulfonic acid monomer, acrylamide monomer and acrylic ester monomer.

Preferably, the initiator is one or more of dibenzoyl peroxide, potassium persulfate and ammonium persulfate.

Preferably, the nanocellulose is one or more of nanocellulose whiskers and nanocellulose fibers.

Preferably, the water reducer is one or more of lignosulfonate water reducer, naphthalene sulfonate water reducer and polycarboxylic acid high-energy water reducer.

The preparation method of the multistage interpenetrating network modified cement-based composite material comprises the following steps of S1, weighing 90-100 parts of cementing material, 1-5 parts of multipolymer monomer, 0.001-0.003 part of cross-linking agent, 0.005-0.015 part of initiator, 0.005-0.04 part of catalyst, 0.01-0.5 part of nano cellulose, 0.15-0.25 part of defoaming agent, 0.5-1.5 part of water reducer, 0-1.4 part of sodium hydroxide and 35-55 parts of mixing water according to parts by weight;

s2, adding 0.01-0.5 part of nano cellulose into 35-55 parts of mixing water, magnetically stirring at room temperature, and then performing ultrasonic dispersion to obtain a nano cellulose solution;

s3, sequentially adding 1-5 parts of multipolymer monomer, 0-1.4 parts of sodium hydroxide and 0.001-0.003 part of cross-linking agent into the nanocellulose solution in S2, magnetically stirring at room temperature, then placing into a vacuum drying oven, taking out, sequentially adding 0.005-0.015 part of initiator and 0.005-0.04 part of catalyst, and stirring at room temperature to obtain precursor mixed solution;

s4, adding 0.15-0.25 part of defoamer and 0.5-1.5 parts of water reducer into the precursor mixed solution in the S3, and magnetically stirring at room temperature to obtain mixed solution;

s5, adding 90-100 parts of cementing materials into the mixed solution in the S4, and stirring at a slow speed and then stirring rapidly to obtain a multistage interpenetrating network modified cement-based composite material;

s6, injecting the multistage interpenetrating network modified cement-based composite material in the S5 into a mold, and curing the test piece after the test piece is coated for 24 hours at room temperature.

Preferably, the defoaming agent is one or more of an organic defoaming agent, a polyether defoaming agent and an organosilicon defoaming agent.

Preferably, the cementitious material is one or more of Portland cement having a strength grade of 42.5 and Portland cement having a strength grade of 52.5.

Therefore, the multistage interpenetrating network modified cement-based composite material adopting the components and the preparation method thereof have the beneficial effects that:

1. functionality with strong electronegativity in high molecular chain of multipolymer monomerThe hydrogen bond action is generated between the energy group and the nano cellulose fiber (CNF), the electronegativity of the atoms in the functional group contained in the multipolymer monomer is related to the bond energy strength of the hydrogen bond, and the functional group (such as-NH) which has high electronegativity and is easy to generate hydrogen bond with the nano cellulose fiber is needed to be selected ₂ -NHR, c=o, etc.) promote dispersion of nanocellulose fibers, and effectively induce uniform dispersion of CNF, driving formation of secondary fiber interpenetrating networks thanks to the regulation and control effect of the polymer three-dimensional network;

2. in-situ polymerization is carried out on the anionic monomer and the vinyl monomer in the multipolymer monomer in the cement matrix by a free radical polymerization method, so that a uniform interpenetrating three-dimensional block copolymer network formed in the cement matrix is synchronously polymerized, the anionic functional group in the high molecular chain of the anionic monomer and the metal ion in the cement matrix are mutually enhanced by complexation, and the microstructure of the cement-based material is entangled and restrained on the nanometer scale;

3. the phase composition of a hydration product of the cementing material and the bonding effect of two-phase materials are further optimized through the short circuit effect and physical crosslinking of a large number of hydroxyl groups and basic hydrolyzed carboxylate ions in the CNF network, so that the secondary CNF network can prevent the generation and the expansion of cracks on a micrometer scale;

4. the invention creatively takes a multipolymer monomer as a primary network, cellulose nanofiber as a secondary network, and forms a multistage interpenetrating network cement-based composite material which is uniformly entangled with a cementing material hydration product through a preparation method of in-situ polymerization and synchronous induction;

5. the invention effectively solves the problems of poor integrity and low toughening efficiency caused by the phase separation and agglomeration effects of the traditional toughening material, and improves the damping performance of the multistage interpenetrating network modified cement-based composite material on microcracks under the double dimensions of nanometer and micrometer.

The technical scheme of the invention is further described in detail through examples.

Detailed Description

The technical scheme of the invention is further described below by examples.

Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.

Example 1

100 parts of cementing material, 3 parts of multipolymer monomer, 0.0015 part of cross-linking agent, 0.01 part of initiator, 0.024 part of catalyst, 0.05 part of nano cellulose, 0.2 part of defoamer, 0.5 part of water reducer, 0.33 part of sodium hydroxide and 45 parts of mixed water are weighed according to the parts by mass.

Wherein the cementing material is ordinary Portland cement with the strength grade of 42.5;

AR of sodium hydroxide is more than or equal to 96.0%;

the multipolymer monomer is acrylamide monomer, N-methylol acrylamide monomer and acrylic acid monomer according to the mol ratio of 1:0.8:0.2;

nanocellulose is a nanocellulose fiber, which has a length of 300 μm and a diameter of 10 nm;

the cross-linking agent is N-N methylene bisacrylamide, the initiator is potassium persulfate, the catalyst is tetramethyl ethylenediamine, the defoamer is tributyl phosphate, and the water reducer is a polycarboxylic acid high-energy water reducer.

S2, adding 0.05 part of nano cellulose fiber into 45 parts of mixing water, magnetically stirring at 600 rpm at room temperature for 10 min, and then performing ultrasonic dispersion to obtain a nano cellulose fiber solution.

S3, mixing an acrylamide monomer, an N-methylol acrylamide monomer and an acrylic acid monomer according to a molar ratio of 1:0.8:0.2 to obtain a multipolymer monomer, and sequentially adding 3 parts of multipolymer monomer, 0.33 part of sodium hydroxide and 0.0015 part of N-N methylene bisacrylamide into the nano cellulose fiber solution in the S2. After stirring magnetically at 600 rpm for 10 min at room temperature, the mixture was placed in a vacuum oven and deoxygenated at 0.1 atm for 7 min at room temperature. Taking out, adding 0.01 part of potassium persulfate and 0.024 part of tetramethyl ethylenediamine in sequence, and stirring at 350 rpm at room temperature for 2 min to obtain a precursor mixed solution.

S4, adding 0.2 part of tributyl phosphate and 0.5 part of polycarboxylic acid high-energy water reducer into the precursor mixed solution in the S3, and magnetically stirring at 300 rpm at room temperature for 3 min to obtain the mixed solution.

And S5, adding 100 parts of ordinary Portland cement with the strength level of 42.5 into the mixed solution in the step S4, slowly stirring for 1 min at 145 rpm, and rapidly stirring for 2 min at 200 rpm to obtain the multistage interpenetrating network modified cement-based composite material.

S6, injecting the multistage interpenetrating network modified cement-based composite material in the S5 into a mould, coating a film at the room temperature of 24 and h, and curing the test piece to 28 d in a curing box with the relative humidity of 95 percent at 20+/-2 ℃.

Example 2

This example differs from example 1 in that the multipolymer monomer was acrylamide, N-methylolacrylamide and 2-acrylamido-2-methylpropanesulfonic acid, mixed in a molar ratio of 1:0.8:0.2, with 0.12 parts sodium hydroxide, the remainder remaining in accordance with example 1.

Example 3

This example differs from example 1 in that the multipolymer monomer was acrylamide, N-methylolacrylamide and methacrylic acid in a molar ratio of 1:0.8:0.2, sodium hydroxide 0.28 parts, and the remainder remained the same as in example 1.

Example 4

This example differs from example 1 in that the multipolymer monomer is 1 part, the multipolymer monomer is acrylamide, N-methylolacrylamide and acrylic acid monomer are mixed in a molar ratio of 1:0.8:0.2, and the remainder remains the same as in example 1.

Example 5

This example differs from example 1 in that the nanocellulose fibers are 0.1 part, the remainder remaining in agreement with example 1.

Example 6

This example differs from example 1 in that the multipolymer monomer was acrylamide, N-methylolacrylamide and acrylic acid monomer mixed in a molar ratio of 1:0.8:0.2, with 1.33 parts sodium hydroxide, the remainder remaining consistent with example 1.

Example 7

This example differs from example 1 in that the potassium persulfate was 0.015 part, and the remainder remained the same as in example 1.

Example 8

This example differs from example 1 in that N-N methylene bisacrylamide was 0.002 parts, and the remainder remained the same as in example 1.

Example 9

This example was different from example 1 in that 50 parts of water was mixed, and the rest was the same as example 1.

Example 10

The flexural strength test was performed on the cement-based composite materials of examples 1 to 9 and comparative examples 1 to 5 with reference to GB/T50081-2019 Standard for test methods for physical mechanical Properties of concrete, and the flexural strength results are shown in Table 1.

Table 1, flexural Properties of Cement-based composite for 7 days and 28 days

As is clear from Table 1, in examples 1 to 9, the flexural strengths for 7 days and 28 days were 9.1 to 12.4 MPa and 12.2 to 17.3 MPa, respectively. The flexural strength of examples 1-9 was increased by 51.6% -106.7% and 67.1% -137.0% compared to 7 days and 28 days of comparative examples 1-3, respectively. The multi-stage interpenetrating network modified cement-based composite material obtained by adopting the method of in-situ polymerization and synchronous induction in the examples 1-9 has higher flexural strength compared with the flexural strength of 7 days and 28 days in the comparative examples 4-5.

Comparative example 1

45 parts of mixing water was poured into 100 parts of cement and stirred for 3 min, 145 rpm was first stirred slowly for 1 min, 200 rpm was then stirred rapidly for 2 min, and the resulting freshly mixed slurry was poured into a mold. After the room temperature is covered with 24-h, the test piece is placed in a curing box with the ambient temperature of 20+/-2 ℃ and the relative humidity of 95% to be cured to 28-d.

Comparative example 2

S1, adding 0.05 part of 10-nm-diameter and 300-mu-m-length nano cellulose fibers into 45 parts of mixing water, magnetically stirring for 5 min at room temperature at 500 rpm, and then placing the mixture in a 480-W-power ultrasonic dispersing machine for ultrasonic dispersion for 10 min to uniformly disperse the nano cellulose fibers in the water to obtain a nano cellulose fiber solution.

S2, pouring the mixed solution in the step S1 into 100 parts of 42.5-grade ordinary Portland cement, stirring for 3 min, firstly stirring for 1 min at 145 rpm, then stirring for 2 min at 200 rpm, and injecting the obtained fresh slurry into a die. After the room temperature is covered with 24-h, the test piece is placed in a curing box with the ambient temperature of 20+/-2 ℃ and the relative humidity of 95% to be cured to 28-d.

Comparative example 3

S1, 3 parts of acrylamide, N-methylol acrylamide and acrylic acid monomer which are mixed according to a molar ratio of 1:0.8:0.2 are added into 45 parts of mixing water, 0.33 part of sodium hydroxide is added, then 0.0015 part of N, N-methylene acrylamide is added, and the mixture is magnetically stirred at 600 rpm for 10 minutes until the mixture is completely dissolved to obtain a mixed solution. The mixed solution was placed in a vacuum oven and deoxygenated at 0.1 atm for 7 min at room temperature. Then, 0.01 part of potassium persulfate and 0.024 part of tetramethyl ethylenediamine were added thereto and stirred at 350 rpm for 2 minutes at room temperature.

S2, pouring the mixed solution in the step S1 into 100 parts of 42.5-grade ordinary Portland cement, stirring for 3 min, firstly stirring for 1 min at 145 rpm, then stirring for 2 min at 200 rpm, and injecting the newly-mixed slurry into a die. After the room temperature is covered with 24-h, the test piece is placed in a curing box with the ambient temperature of 20+/-2 ℃ and the relative humidity of 95% to be cured to 28-d.

Comparative example 4

S1, adding 0.05 part of 10-nm-diameter and 300-mu-m-length nanocellulose fibers into 45 parts of mixing water, and magnetically stirring at room temperature for 5 min at 500 rpm. And then the mixture is placed in an ultrasonic dispersing machine with 480W power for ultrasonic dispersion for 10 minutes to obtain a nano cellulose fiber solution.

S2, adding 3 parts of polymerized poly (acrylamide-N-methylol acrylamide-sodium acrylate) into the nano cellulose fiber solution in S1, and stirring for 2 min at the room temperature at 350 rpm. And then adding 0.2 part of tributyl phosphate and 0.5 part of polycarboxylic acid high-performance water reducer, and magnetically stirring at 300 rpm for 3 min at room temperature to obtain a mixed solution for later use.

S3, pouring the mixed solution obtained in the step S2 into 100 parts of 42.5-grade ordinary Portland cement, stirring for 3 min, firstly, stirring for 1 min at 145 rpm and then stirring for 2 min at 200 rpm, and obtaining the freshly mixed slurry. And (3) injecting the freshly mixed slurry into a mould, coating the freshly mixed slurry with the mould at room temperature of 24-h, and placing the test piece in a curing box with the ambient temperature of 20+/-2 ℃ and the relative humidity of 95% for curing to 28-d.

Comparative example 5

S1, adding 0.05 part of 10-nm-diameter and 300-mu-m-length nano cellulose fibers into 25 parts of mixing water, magnetically stirring at room temperature for 5 min at 500 rpm, and then placing in a 480-W-power ultrasonic dispersing machine for ultrasonic dispersion for 10 min to obtain a nano cellulose fiber solution.

S2, mixing an acrylamide monomer, an N-methylol acrylamide monomer and an acrylic acid monomer according to a molar ratio of 1:0.8:0.2 to obtain a multipolymer monomer, adding 3 parts of multipolymer monomer into 20 parts of mixing water, and adding 0.33 part of sodium hydroxide. Then, 0.0015 parts of N, N-methylene acrylamide was added thereto, and the mixture was magnetically stirred at 600 rpm at room temperature for 10 minutes to obtain a mixed solution.

The mixed solution was placed in a vacuum drying oven, deoxygenated for 7 min at room temperature of 0.1 atm, followed by adding 0.01 part of potassium persulfate and 0.024 part of tetramethyl ethylenediamine, and stirring at 350 rpm for 2 min at room temperature, to obtain a precursor mixed solution. And adding 0.2 part of tributyl phosphate and 0.5 part of polycarboxylic acid high-performance water reducer into the precursor mixed solution, and magnetically stirring at 300 rpm for 3 min at room temperature for later use.

And S3, sequentially pouring the solutions obtained in the steps S1 and S2 into 100 parts of 42.5-grade ordinary Portland cement, stirring for 3 min, firstly, slowly stirring for 1 min at 145 rpm, and then, rapidly stirring for 2 min at 200 rpm, thereby obtaining the multistage interpenetrating network modified cement-based composite material.

Injecting the multistage interpenetrating network modified cement-based composite material into a mould, coating the mould at room temperature of 24-h, placing the test piece in a curing box with the ambient temperature of 20+/-2 ℃ and the relative humidity of 95%, and curing to 28-d.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting it, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that: the technical scheme of the invention can be modified or replaced by the same, and the modified technical scheme cannot deviate from the spirit and scope of the technical scheme of the invention.

Claims (6)

1. A multi-stage interpenetrating network modified cement-based composite material, characterized in that: the components in parts by weight are: 90-100 parts of cementing material, 1-5 parts of multipolymer monomer, 0.001-0.003 part of cross-linking agent, 0.005-0.015 part of initiator, 0.005-0.04 part of catalyst, 0.01-0.5 part of nano cellulose, 0.15-0.25 part of defoamer, 0.5-1.5 parts of water reducer, 0-1.4 parts of sodium hydroxide and 35-55 parts of mixing water.

2. A multi-stage interpenetrating network modified cement-based composite material according to claim 1, characterized in that: the multipolymer monomer is one or more of acrylic monomer, 2-acrylic amide-2-methylpropanesulfonic acid monomer, acrylamide monomer and acrylic ester monomer.

3. A multi-stage interpenetrating network modified cement-based composite material according to claim 1, characterized in that: the initiator is one or more of dibenzoyl peroxide, potassium persulfate and ammonium persulfate.

4. A multi-stage interpenetrating network modified cement-based composite material according to claim 1, characterized in that: the nanocellulose is one or more of nanocellulose whisker and nanocellulose fiber.

5. A multi-stage interpenetrating network modified cement-based composite material according to claim 1, characterized in that: the water reducer is one or more of lignosulfonate water reducer, naphthalene sulfonate water reducer and polycarboxylic acid high-energy water reducer.

6. A method for preparing a multistage interpenetrating network modified cement-based composite material according to any one of claims 1 to 5, characterized in that: s1, weighing 90-100 parts of cementing material, 1-5 parts of multipolymer monomer, 0.001-0.003 part of cross-linking agent, 0.005-0.015 part of initiator, 0.005-0.04 part of catalyst, 0.01-0.5 part of nano cellulose, 0.15-0.25 part of defoamer, 0.5-1.5 part of water reducer, 0-1.4 part of sodium hydroxide and 35-55 parts of mixing water according to parts by weight;

s2, adding 0.01-0.5 part of nano cellulose into 35-55 parts of mixing water, magnetically stirring at room temperature, and then performing ultrasonic dispersion to obtain a nano cellulose solution;

s3, sequentially adding 1-5 parts of multipolymer monomer, 0-0.4 part of sodium hydroxide and 0.001-0.003 part of cross-linking agent into the nanocellulose solution in S2, magnetically stirring at room temperature, then placing into a vacuum drying oven, taking out, sequentially adding 0.005-0.015 part of initiator and 0.005-0.04 part of catalyst, and stirring at room temperature to obtain precursor mixed solution;

s4, adding 0.15-0.25 part of defoamer and 0.5-1.5 parts of water reducer into the precursor mixed solution in the S3, and magnetically stirring at room temperature to obtain mixed solution;

s5, adding 90-100 parts of cementing materials into the mixed solution in the S4, and stirring at a slow speed and then stirring rapidly to obtain a multistage interpenetrating network modified cement-based composite material;

s6, injecting the multistage interpenetrating network modified cement-based composite material in the S5 into a mold, and curing the test piece after the test piece is coated for 24 hours at room temperature.