CN115572111B - Preparation method of modified nanocellulose reinforced high-crack-resistance cement - Google Patents
Preparation method of modified nanocellulose reinforced high-crack-resistance cement Download PDFInfo
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- 239000004568 cement Substances 0.000 title claims abstract description 100
- 229920001046 Nanocellulose Polymers 0.000 title claims abstract description 75
- 238000002360 preparation method Methods 0.000 title claims abstract description 28
- 239000000243 solution Substances 0.000 claims abstract description 45
- 238000003756 stirring Methods 0.000 claims abstract description 41
- 229920002678 cellulose Polymers 0.000 claims abstract description 28
- 239000001913 cellulose Substances 0.000 claims abstract description 28
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 18
- 108010059892 Cellulase Proteins 0.000 claims abstract description 17
- 229940106157 cellulase Drugs 0.000 claims abstract description 17
- 238000006243 chemical reaction Methods 0.000 claims abstract description 17
- 239000003607 modifier Substances 0.000 claims abstract description 15
- 238000005406 washing Methods 0.000 claims abstract description 15
- 239000000835 fiber Substances 0.000 claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 9
- 230000001105 regulatory effect Effects 0.000 claims abstract description 8
- 238000000465 moulding Methods 0.000 claims abstract description 6
- 239000000843 powder Substances 0.000 claims abstract description 6
- 239000001509 sodium citrate Substances 0.000 claims abstract description 6
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims abstract description 6
- 239000007853 buffer solution Substances 0.000 claims abstract description 5
- 238000001816 cooling Methods 0.000 claims abstract description 5
- 230000000415 inactivating effect Effects 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims abstract description 5
- 238000000967 suction filtration Methods 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 23
- 238000002156 mixing Methods 0.000 claims description 14
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical group [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 13
- 238000000502 dialysis Methods 0.000 claims description 7
- 235000017166 Bambusa arundinacea Nutrition 0.000 claims description 5
- 235000017491 Bambusa tulda Nutrition 0.000 claims description 5
- 241001330002 Bambuseae Species 0.000 claims description 5
- 235000015334 Phyllostachys viridis Nutrition 0.000 claims description 5
- 239000011425 bamboo Substances 0.000 claims description 5
- 230000002779 inactivation Effects 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
- 238000010907 mechanical stirring Methods 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000012360 testing method Methods 0.000 description 58
- 239000002134 carbon nanofiber Substances 0.000 description 33
- 239000004567 concrete Substances 0.000 description 32
- 239000000203 mixture Substances 0.000 description 18
- 230000004048 modification Effects 0.000 description 10
- 238000012986 modification Methods 0.000 description 10
- 239000004576 sand Substances 0.000 description 10
- 239000003638 chemical reducing agent Substances 0.000 description 8
- 239000002131 composite material Substances 0.000 description 8
- 238000001035 drying Methods 0.000 description 8
- 238000011049 filling Methods 0.000 description 6
- 239000004033 plastic Substances 0.000 description 6
- 239000004575 stone Substances 0.000 description 6
- 238000005266 casting Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 4
- 238000005336 cracking Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 239000010881 fly ash Substances 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 230000007071 enzymatic hydrolysis Effects 0.000 description 3
- 238000006047 enzymatic hydrolysis reaction Methods 0.000 description 3
- 239000002086 nanomaterial Substances 0.000 description 3
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000007580 dry-mixing Methods 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000012779 reinforcing material Substances 0.000 description 2
- 238000007790 scraping Methods 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- -1 Alkyl quaternary ammonium salts Chemical class 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 239000002028 Biomass Substances 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- 102000004190 Enzymes Human genes 0.000 description 1
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 239000003899 bactericide agent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000003093 cationic surfactant Substances 0.000 description 1
- 239000011083 cement mortar Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 235000013399 edible fruits Nutrition 0.000 description 1
- 239000003995 emulsifying agent Substances 0.000 description 1
- 229940088598 enzyme Drugs 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000008396 flotation agent Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000005543 nano-size silicon particle Substances 0.000 description 1
- 239000002121 nanofiber Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 239000010893 paper waste Substances 0.000 description 1
- 230000029553 photosynthesis Effects 0.000 description 1
- 238000010672 photosynthesis Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000001132 ultrasonic dispersion Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention discloses a preparation method of modified nanocellulose reinforced high crack resistance cement, which comprises the steps of crushing a cellulose pulp board, adding sodium citrate buffer solution, adjusting the pH value to 5.0-7.0, heating to 60-80 ℃, adding cellulase, mechanically stirring for continuous reaction, and dispersing an enzymolysis product obtained by the reaction under an ultrasonic condition; heating up, inactivating cellulase, cooling, separating nano cellulose fibers from a reaction solution through suction filtration and washing, dialyzing after washing, and collecting a nano cellulose solution; adding sodium hydroxide solution into the solution, regulating the pH value of the solution to 7.0, adding modifier powder, and carrying out ultrasonic stirring reaction in a normal temperature environment to obtain modified nanocellulose solution; and adding the obtained modified nano cellulose solution in the preparation process of the cement cementing material, uniformly stirring, pouring and molding, curing at normal temperature, demolding, and curing in a standard curing room to obtain the modified nano cellulose reinforced high-crack-resistance cement.
Description
Technical Field
The invention belongs to the technical field of composite materials, and particularly relates to a preparation method of modified nanocellulose reinforced high-crack-resistance cement.
Background
Nanomaterials such as nanosilicon dioxide, carbon nanotubes and the like have been the subject of extensive investigation as reinforcing materials. The nano material is added into the cement material, so that the tensile property, the elastic modulus, the volcanic ash property and the like of the composite material can be improved. The inorganic nano material has the advantages of harsh preparation conditions, general dispersibility and great health risks.
In contrast, nanocellulose (Cellulose nanofiber, hereinafter abbreviated as CNF) is more readily available, readily dispersible in solution, green and non-toxic. CNFs are generally whisker-shaped, having a width of between tens of nanometers and tens of nanometers, and a length of between tens of nanometers and hundreds of nanometers. Cellulose is a natural biomass polymer with the largest yield in the world, and is mainly synthesized by photosynthesis; waste paper pulp, fruit shells, crushed wood dust and the like can be used as raw materials for preparing CNF, and CNF is a novel environment-friendly nano reinforcing material and has great application potential in the field of cement composite materials.
However, CNF prepared by enzymatic hydrolysis at present has a negative Zeta potential, which is a major cause of hindering further improvement of its compatibility with cement.
Disclosure of Invention
The invention aims to provide a modified nano-cellulose reinforced cement-based composite material and a preparation method thereof, wherein the nano-cellulose is modified to prepare the cement-based composite material with more excellent mechanical property and crack resistance.
In order to achieve the above purpose, the following technical scheme is adopted:
the preparation method of the modified nanocellulose reinforced high-crack-resistance cement comprises the following steps:
(1) Crushing a cellulose pulp plate, adding a sodium citrate buffer solution, regulating the pH value to 5.0-7.0, heating to 60-80 ℃, adding cellulase, mechanically stirring for continuous reaction, and dispersing an enzymolysis product obtained by the reaction under an ultrasonic condition;
(2) Heating up, inactivating cellulase, cooling, separating nano cellulose fibers from a reaction solution through suction filtration and washing, dialyzing after washing, and collecting a nano cellulose solution;
(3) Adding sodium hydroxide solution into the solution, regulating the pH value of the solution to 7.0, adding modifier powder, and carrying out ultrasonic stirring reaction in a normal temperature environment to obtain modified nanocellulose solution;
(4) And adding the obtained modified nano cellulose solution in the preparation process of the cement cementing material, uniformly stirring, pouring and molding, curing at normal temperature, demolding, and curing in a standard curing room to obtain the modified nano cellulose reinforced high-crack-resistance cement.
According to the scheme, the cellulose pulp board in the step 1 is a bamboo pulp board; the concentration of the cellulase is 200unit/mL.
According to the scheme, the mechanical stirring speed in the step 1 is 300-1000 r/min, and stirring is continued for 5h.
According to the scheme, the inactivation temperature of the cellulase in the step 2 is 100 ℃ for 10min.
According to the scheme, the specific process of dialysis after washing in the step 2 comprises the following steps: repeatedly washing with water for 3 times, and dialyzing in dialysis bag for 48 hr.
According to the scheme, the modifier in the step 3 is a quaternary ammonium salt surfactant; the mass ratio of the modifier to the nanocellulose is 1:4.
According to the above scheme, the preferred modifier in step 3 is cetyltrimethylammonium bromide (CTAB).
According to the scheme, in the step 3, the ultrasonic power is 50-100W, the frequency is 50-100 kHz, and the reaction time is 3 hours.
According to the scheme, the mixing amount of the modified nanocellulose in the step 4 is 0.05-0.2% of the cement mass.
Compared with the prior art, the invention has the following beneficial effects:
the cellulase can selectively hydrolyze amorphous regions of lower crystallinity of the fibril while regions of higher crystallinity are retained, resulting in an elongated morphology CNF of greater aspect ratio.
Alkyl quaternary ammonium salts are one of the important varieties of quaternary ammonium salt type cationic surfactants, and have been widely used as bactericides, fiber softeners, mineral flotation agents, emulsifiers, and the like. The structural feature is that the nitrogen atom is connected with four alkyl groups, namely ammonium ion NH 4 + All four hydrogen atoms of the modified CNF are replaced by alkyl groups, and the rich hydroxyl on the surface of the CNF is replaced, so that the zeta potential of the modified CNF in the solution is positive.
The modified cellulose reinforced high-crack-resistance cement composite material prepared by the invention belongs to a novel green environment-friendly cement composite material; the modified cellulose improves the hydration degree of cement and promotes the generation of cement hydration products; the prepared modified cellulose reinforced cement paste has good mechanical property, the compression strength of the modified cellulose reinforced cement paste with the doping amount of 0.15% is improved by 20.5% compared with that of the modified cellulose (control group) 28d, the flexural strength of the modified cellulose reinforced cement paste with the doping amount of 0.15% is improved by 26.7% compared with that of the control group 28d, and meanwhile, the plastic shrinkage crack of the concrete in the early age period is obviously reduced and the drying shrinkage is reduced.
Drawings
Fig. 1: the compressive strength of the modified nanocellulose reinforced cement paste.
Fig. 2: the modified nanocellulose enhances the flexural strength of the cement paste.
Fig. 3: TEM image of nanocellulose after enzymatic hydrolysis.
Fig. 4: XRD patterns before and after nanocellulose modification.
Fig. 5: infrared spectrogram of nanocellulose before and after modification.
Fig. 6: x-ray photoelectron spectrum wide scanning spectrogram before and after nanocellulose modification.
Fig. 7: and (5) comparing the concrete plastic shrinkage cracking experimental results.
Fig. 8: and (5) comparing the concrete drying shrinkage experimental results.
Detailed Description
The following examples further illustrate the technical aspects of the present invention, but are not intended to limit the scope of the present invention.
The specific embodiment provides a preparation method of modified nanocellulose reinforced high-crack-resistance cement, which comprises the following steps:
(1) Crushing a cellulose pulp plate, adding a sodium citrate buffer solution, regulating the pH value to 5.0-7.0, heating to 60-80 ℃, adding cellulase, mechanically stirring for continuous reaction, and dispersing an enzymolysis product obtained by the reaction under an ultrasonic condition;
(2) Heating up, inactivating cellulase, cooling, separating nano cellulose fibers from a reaction solution through suction filtration and washing, dialyzing after washing, and collecting a nano cellulose solution;
(3) Adding sodium hydroxide solution into the solution, regulating the pH value of the solution to 7.0, adding modifier powder, and performing ultrasonic stirring reaction for 3 hours in a normal temperature environment to obtain modified nanocellulose solution;
(4) And adding the obtained modified nano cellulose solution in the preparation process of the cement cementing material, uniformly stirring, pouring and molding, curing at normal temperature, demolding, and curing in a standard curing room to obtain the modified nano cellulose reinforced high-crack-resistance cement.
Specifically, the cellulose pulp board in the step 1 is a bamboo pulp board; the concentration of the cellulase is 200unit/mL.
Specifically, the cellulase inactivation temperature in step 2 is 100℃for 10min.
Specifically, the specific process of dialysis after washing in step 2 is as follows: repeatedly washing with water for 3 times, and dialyzing in dialysis bag for 48 hr.
Specifically, the modifier in the step 3 is a quaternary ammonium salt surfactant; the mass ratio of the modifier to the nanocellulose is 1:4.
Specifically, the preferred modifier in step 3 is cetyltrimethylammonium bromide (CTAB).
Specifically, the stirring speed is 300-1000 r/min, and stirring is continued for 5 hours; the ultrasonic power is 50-100W, and the frequency is 50-100 kHz.
Specifically, the mixing amount of the modified nanocellulose in the step 4 is 0.05-0.2% of the cement mass.
The raw materials used in the specific examples are as follows:
sulfate bamboo pulp board (cellulose content)>95 percent of cellulase (200 unit/mL), sodium citrate (analytically pure), sodium hydroxide (analytically pure), oil well cement (grade G), modifier cetyl trimethylammonium bromide (C) 19 H 42 BrN, abbreviated CTAB, analytically pure), laboratory deionized water.
Example 1
50g of crushed bamboo pulp board raw material is taken, added into a reaction vessel, added with a prepared sodium citrate buffer solution, adjusted to pH value of 5.0, the temperature of 60 ℃ and added with a proper amount of cellulase with concentration of 200unit/mL. And (3) mechanically stirring at the rotating speed of 300r/min, continuously reacting for 5 hours, and performing ultrasonic dispersion on the enzymolysis product under the conditions of 99W of power and 80kHz of frequency. Heating the product in a beaker at 100 ℃ in water bath for 10min, inactivating enzyme, cooling to room temperature, separating CNF from reaction liquid by suction filtration and washing, repeatedly adding water for 3 times, putting into a dialysis bag, dialyzing for 48h, and collecting nanocellulose solution. Adding 9% sodium hydroxide solution into CNF solution, regulating pH value to 7.0, adding modifier CTAB powder, wherein the mass ratio of the modifier powder to CNF is 1:4, placing the mixed solution under ultrasonic condition, and reacting at power of 99W, frequency of 80kHz and temperature of 30 ℃ for 3h to obtain modified nanocellulose solution.
Uniformly mixing the modified nanocellulose solution and cement, adding the mixture into a stirring pot at the rotating speed of 700r/min, continuously stirring for 85s, stopping stirring for 15s, and checking whether cement paste is uniformly stirred and whether the paste overflows or not; continuously stirring at the rotating speed of 700r/min for 85s to obtain cement paste; after the preparation of the cement paste is finished, the cement paste is put into a standard mould coated with a release agent twice, a spatula is used for continuously inserting and tamping each time of casting, and the cement paste is put into a vibrating table for vibrating for 2 minutes after being put into the mould, so that large bubbles in the paste are reduced, a test piece is more uniform and compact, and redundant paste around the test piece is scraped. And (3) after being placed at room temperature for 24 hours, removing the mould, placing the mould into a standard constant temperature and constant humidity curing box with the relative humidity of 90+/-5% and the temperature of 20 ℃ for curing until the specified age (3 d, 7d and 28 d) to obtain the modified nanocellulose reinforced cement paste test piece. In the preparation process, the modified CNF is 0.05 percent (by mass ratio) of the dosage of the cement.
Example 2
The procedure for the preparation of the modified nanocellulose solution was the same as in example 1.
Uniformly mixing the modified nanocellulose solution and cement, adding the mixture into a stirring pot, continuously stirring at the rotating speed of 700r/min for 85s, stopping stirring for 15s, and checking whether cement paste is uniformly stirred and whether the paste overflows or not; continuously stirring at the rotating speed of 700r/min for 85s to obtain cement paste; after the preparation of the cement paste is finished, the cement paste is put into a standard mould coated with a release agent twice, a spatula is used for continuously inserting and tamping each time of casting, and the cement paste is put into a vibrating table for vibrating for 2 minutes after being put into the mould, so that large bubbles in the paste are reduced, a test piece is more uniform and compact, and redundant paste around the test piece is scraped. And (3) after being placed at room temperature for 24 hours, removing the mould, placing the mould into a standard constant temperature and constant humidity curing box with the relative humidity of 90+/-5% and the temperature of 20 ℃ for curing until the specified age (3 d, 7d and 28 d) to obtain the modified nanocellulose reinforced cement paste test piece. In the preparation process, the modified CNF is 0.10 percent (by mass ratio) of the dosage of the cement.
Example 3
The procedure for the preparation of the modified nanocellulose solution was the same as in example 1.
Uniformly mixing the modified nanocellulose solution and cement, adding the mixture into a stirring pot, continuously stirring at the rotating speed of 700r/min for 85s, stopping stirring for 15s, and checking whether cement paste is uniformly stirred and whether the paste overflows or not; continuously stirring at the rotating speed of 700r/min for 85s to obtain cement paste; after the preparation of the cement paste is finished, the cement paste is put into a standard mould coated with a release agent twice, a spatula is used for continuously inserting and tamping each time of casting, and the cement paste is put into a vibrating table for vibrating for 2 minutes after being put into the mould, so that large bubbles in the paste are reduced, a test piece is more uniform and compact, and redundant paste around the test piece is scraped. And (3) after being placed at room temperature for 24 hours, removing the mould, placing the mould into a standard constant temperature and constant humidity curing box with the relative humidity of 90+/-5% and the temperature of 20 ℃ for curing until the specified age (3 d, 7d and 28 d) to obtain the modified nanocellulose reinforced cement paste test piece. In the preparation process, the modified CNF is 0.15 percent (by mass ratio) of the dosage of the cement. .
Example 4
The procedure for the preparation of the modified nanocellulose solution was the same as in example 1.
Uniformly mixing the modified nanocellulose solution and cement, adding the mixture into a stirring pot, continuously stirring at the rotating speed of 700r/min for 85s, stopping stirring for 15s, and checking whether cement paste is uniformly stirred and whether the paste overflows or not; continuously stirring at the rotating speed of 700r/min for 85s to obtain cement paste; after the preparation of the cement paste is finished, the cement paste is put into a standard mould coated with a release agent twice, a spatula is used for continuously inserting and tamping each time of casting, and the cement paste is put into a vibrating table for vibrating for 2 minutes after being put into the mould, so that large bubbles in the paste are reduced, a test piece is more uniform and compact, and redundant paste around the test piece is scraped. And (3) after being placed at room temperature for 24 hours, removing the mould, placing the mould into a standard constant temperature and constant humidity curing box with the relative humidity of 90+/-5% and the temperature of 20 ℃ for curing until the specified age (3 d, 7d and 28 d) to obtain the modified nanocellulose reinforced cement paste test piece. In the preparation process, the modified CNF is 0.20 percent (by mass ratio) of the dosage of the cement.
Example 5
The procedure for the preparation of the modified nanocellulose solution was the same as in example 1.
Concrete mixing ratio (kg/m) 3 ) Cement 376: water 164: sand 704: crushed stone 1056: : fly ash 66: the water reducer 4.865 has a water cement ratio of 0.38, wherein the sand is formed by mixing machine-made sand (70%) and fine sand (30%), the fineness modulus is 2.7, the crushed stone particle size is 5-25mmm, and the water reducer is a high-efficiency poly (acid ester) water reducer. The target slump of the fresh concrete is 160-180mm, and the designed strength grade is C40. Adding crushed stone, sand, cement and fly ash in sequence in a stirrer, dry-mixing for 1min, uniformly mixing the modified nanocellulose solution with water within 30s, adding the mixture into the stirrer, continuously stirring for 2min (adding the water reducer during the stirring), stopping stirring for 30s, checking whether concrete is uniformly stirred and whether segregation exists or not, and continuously stirring for 30s to obtain the concrete. And (3) filling the concrete mixture into test molds once, inserting and tamping the concrete mixture along the walls of each test mold by using a spatula during filling, enabling the concrete mixture to be higher than a test mold opening, putting the concrete mixture into a vibrating table after filling, vibrating until the surface of the concrete mixture is out of slurry, stopping, and scraping redundant slurry around the concrete mixture. After 24 hours of standing at room temperature, the mold is removed and the relative humidity is put into>And curing in a standard curing room at 20+/-2 ℃ until the curing reaches a specified age (3 d, 7d and 28 d) to obtain the modified nano-cellulose reinforced high-crack-resistance concrete test piece. In the preparation process, the modified nano cellulose is 0.05 percent (by mass ratio) of the dosage of the cement.
Example 6
The procedure for the preparation of the modified nanocellulose solution was the same as in example 1.
Concrete mixing ratio (kg/m) 3 ) Cement 376: water 164: sand 704: crushed stone 1056: : fly ash 66: the water reducer 4.865 has a water cement ratio of 0.38, wherein the sand is formed by mixing machine-made sand (70%) and fine sand (30%), the fineness modulus is 2.7, the crushed stone particle size is 5-25mmm, and the water reducer is a high-efficiency poly (acid ester) water reducer (Jiangsu threbert). The target slump of the freshly mixed concrete is 160-180mm, the strength grade is C40, and the pressure resistance is realized for 28 daysThe strength was 48.2MPa. Adding crushed stone, sand, cement and fly ash in sequence in a stirrer, dry-mixing for 1min, uniformly mixing the modified nanocellulose solution with water within 30s, adding the mixture into the stirrer, continuously stirring for 2min (adding the water reducer during the stirring), stopping stirring for 30s, checking whether concrete is uniformly stirred and whether segregation exists or not, and continuously stirring for 30s to obtain the concrete. And (3) filling the concrete mixture into test molds once, inserting and tamping the concrete mixture along the walls of each test mold by using a spatula during filling, enabling the concrete mixture to be higher than a test mold opening, putting the concrete mixture into a vibrating table after filling, vibrating until the surface of the concrete mixture is out of slurry, stopping, and scraping redundant slurry around the concrete mixture. After 24 hours of standing at room temperature, the mold is removed and the relative humidity is put into>And curing in a standard curing room at 20+/-2 ℃ until the curing reaches a specified age (3 d, 7d and 28 d) to obtain the modified nano-cellulose reinforced high-crack-resistance concrete test piece. In the preparation process, the modified nano cellulose is 0.15 percent (by mass ratio) of the dosage of the cement.
Testing the performance of the modified nano-cellulose reinforced high-crack-resistance cement composite material:
compressive flexural strength: the compressive and fracture-resistant test pieces of the modified nanocellulose cement paste adopt standard prisms with the dimensions of 40mm multiplied by 160mm, 3 test pieces are used for each group of the compressive strength, and 6 test pieces are used for each group of the compressive strength. According to the cement mortar strength test method (GB/T17671); testing was performed on a CDT1305-2 type microcomputer controlled electronic pressure tester manufactured by meites industries systems limited.
Plastic shrinkage of concrete: according to the plastic shrinkage test, ASTM C1579-2013 is consulted, a concrete test piece adopts a plate with the size of 560mm multiplied by 355mm multiplied by 100mm, a high-power fan is used immediately after casting molding to achieve the wind speed of 5m/s on the upper surface of the test piece, a tungsten filament lamp (1 kW) is used for irradiating the surface of the test piece to simulate a sunlight high-temperature environment, and water evaporation on the surface of the test piece is ensured. And (3) testing each group of test pieces, wherein the test environment temperature is room temperature, the relative humidity is not more than 60%, and the test is carried out for 24 hours. After the end of the experiment, an arithmetic average (accurate to 0.001 mm) of 30 readings was taken after measuring the crack width every 1 cm along the centerline of the test piece as the nominal crack width of the test piece.
And (3) drying and shrinking the concrete: drying shrinkage test with reference to the test method of ASTM C157-2017, test pieces were used with unconstrained prisms of dimensions 75mm by 285mm, 3 test pieces per group. Placing the test piece into a standard curing box with the temperature of 20+/-2 ℃ and the relative humidity of 90+/-5% for standard curing within 24 hours after pouring and molding, transferring the test piece into a constant temperature and constant humidity curing box with the temperature of 20+/-2 ℃ and the relative humidity of 60+/-5% after curing for 3 days, and measuring the length change of the test piece by using a dial indicator in different ages.
Compressive strength of cement paste test piece 3 d: as shown in fig. 1, the 3d compressive strength of the cement paste test piece control group is 31.05MPa, the 3d compressive strength of the 0.05% group is 33.92MPa, and the two groups have no obvious difference; the 3d compressive strength of the group consisting of 0.1%, 0.15% and 0.2% is 35.98MPa, 38.81MPa and 32.29MPa respectively, and the 3d compressive strength of the group consisting of 0.15% of the modified nanocellulose cement paste test piece is improved by 25.0% compared with that of the control group, so that the modified nanocellulose cement paste test piece is remarkably improved.
Fig. 1 and 2 show the compressive strength and flexural strength of the modified nanocellulose cement paste, respectively. Wherein, control represents the cement paste without modified nano cellulose, and 0.05 represents the mass of the modified nano cellulose accounting for 0.05% of the mass of the cement; 0.1 represents that the mass of the modified nano cellulose accounts for 0.1% of the mass of the cement; 0.15 represents that the mass of the modified nano cellulose accounts for 0.15% of the mass of the cement; 0.2 represents that the mass of the modified nanocellulose accounts for 0.2% of the mass of the cement. The data were analyzed by one-way variance with 95% confidence intervals, and when there was no common letter above the two groups, it indicated that there was a significant difference between the mean of any two groups of data.
As shown in FIG. 1, the compressive strength of the cement paste test piece control group 7d is 36.29MPa,0.05%, 0.1%, 0.15% and the compressive strength of the 0.2% group 7d are 48.81MPa, 51.75MPa, 47.26MPa and 41.36MPa respectively, wherein the compressive strength of the 0.05%, 0.1% and 0.15% groups are improved by 34.5%, 42.6% and 30.2% respectively compared with the control group, and the compressive strength of the 0.2% group 7d is obviously improved. The compressive strength of the cement paste test piece control group 28d is 49.73MPa,0.05%, 0.1%, 0.15% and 0.2% and the compressive strength of the cement paste test piece control group 28d is 56.90MPa, 56.75MPa, 59.93MPa, 48.88MPa,0.05% group, 0.1% group and 0.15% group are respectively improved by 14.4%, 14.1% and 20.5% compared with the compressive strength of the control group 28d, and the cement paste test piece control group is obviously improved.
Flexural strength of cement paste test piece 3 d: as shown in FIG. 2, the flexural strength of the cement paste test piece control group 3d is 7.47MPa, the flexural strength of the cement paste test piece control group 3d is 9.68MPa, and the flexural strength of the cement paste test piece control group is respectively improved by 29.5 percent compared with the control group; the 3d flexural strength of the 0.05%, 0.15% and 0.2% groups are respectively 8.78MPa, 9.52MPa and 9.24MPa, and compared with the control group, the 3d flexural strength is respectively improved by 17.5%, 27.4% and 23.7%, and the 3d flexural strength is obviously improved.
As shown in FIG. 2, the flexural strength of the cement paste test piece control group 7d is 8.36MPa, the flexural strength of the 0.1% group 7d is 10.5MPa, and the flexural strength is improved by 25.6% compared with the control group; the flexural strength of 7d in the 0.05%, 0.15% and 0.2% groups are respectively 10.18MPa, 10.42MPa and 9.68MPa, which are respectively 21.7%, 24.6% and 15.7% higher than those in the control group, wherein the 0.05% and 0.15% groups are significantly improved, and the 0.2% groups are not significantly different. The flexural strength of the cement paste test piece control group 28d is 9.31MPa, the flexural strength of the 0.15% group 28d is 11.80MPa, and compared with the control group, the flexural strength is improved by 26.7%; the 28d flexural strength of the 0.05%, 0.1% and 0.2% groups were 10.57MPa, 10.89MPa and 10.16MPa respectively, which were improved by 13.5%, 16.9% and 9.1% respectively compared with the control group, wherein the 0.05% and 0.1% groups were significantly improved, while the 0.2% groups were not significantly different.
FIG. 3 is a Transmission Electron Microscope (TEM) image of cellulose enzymatic hydrolysis observed at an acceleration voltage of 200kV and a magnification of 100000, wherein cellulose selectively hydrolyzes amorphous regions of lower crystallinity and regions of higher crystallinity remain, thereby obtaining an elongated morphology of CNF; the CNF morphology is complete and interlaced with each other in a network shape.
Fig. 4 is an XRD diffractogram before and after modification of nanocellulose, where the positions of diffraction peaks of CNF samples before and after modification are substantially identical, and the positions of diffraction peaks correspond to crystal planes of cellulose (101), (002), and (004) at 2θ of 16.6 °, 23.2 °, and 35.4 °, respectively, and belong to typical cellulose type i cellulose. CTAB modification does not alter or disrupt the crystal structure of CNF; the crystallinity of the CNF before and after modification is calculated to be 62.31 percent and 69.40 percent respectively, and the modification treatment improves the crystallinity of the CNF. CTAB can remove impurity components among CNFs, and the CNFs are dispersed after cationization, so that the area of an amorphous region is reduced, and the relative crystallinity of the CNFs is further improved.
FIG. 5 is an infrared spectrum of nanocellulose before and after modificationCNF retains the basic chemical structure of natural cellulose, and has hydroxyl group (-OH) of 3428cm -1 A stretching vibration peak is generated nearby at 2905cm -1 The cellulose C-H bond stretching vibration characteristic peak is 1652cm -1 The vicinity is the O-H characteristic peak of water. In the CTAB-modified CNF sample pattern, C-N bond at 1435cm was present -1 A nearby stretching vibration peak; at 1056-1168 cm -1 The characteristic peaks in the vicinity are all stronger in the modified group than in the unmodified group. These all indicate that CTAB was grafted onto CNF.
FIG. 6 shows the X-ray photoelectron spectrum of the nanocellulose before and after modification, wherein strong peaks appear near 286eV and 543eV, respectively, which are caused by C, O elements contained in CNF. The modified CNF spectra show an N element peak around 400eV, which is caused by CTAB grafted to the CNF surface.
FIG. 7 shows the result of concrete plastic shrinkage cracking experiment control, and the cracking effect of the added unmodified nanocellulose is obvious. At a fiber loading of 0.05%, the plastic shrinkage crack width at the end of the experiment was significantly reduced, presumably the bridging effect (crack bridging effect) of the fiber was on, limiting further expansion of shrinkage cracks due to rapid moisture loss. When the fiber dosage reaches 0.15%, the cracks of the test piece almost disappear, and no cracks are observed by the modified nanocellulose added test piece, and it is speculated that besides the bridging effect of the fibers, the special internal curing effect of the cellulose fibers exists, and shrinkage cracking caused by rapid water loss in the early age is delayed or prevented.
Fig. 8 is a graph showing the results of concrete drying shrinkage experiments, wherein the drying shrinkage of concrete after unmodified CNF is smaller than that of a control group without CNF, the drying shrinkage of concrete is obviously reduced by adding CNF, the shrinkage can be further reduced by increasing the fiber blending amount, and the influence of CTAB modification on long-term drying shrinkage is smaller.
Claims (6)
1. The preparation method of the modified nanocellulose reinforced high-crack-resistance cement is characterized by comprising the following steps of:
(1) Crushing a cellulose pulp plate, adding a sodium citrate buffer solution, regulating the pH value to 5.0-7.0, heating to 60-80 ℃, adding cellulase, mechanically stirring for continuous reaction, and dispersing an enzymolysis product obtained by the reaction under an ultrasonic condition;
(2) Heating up, inactivating cellulase, cooling, separating nano cellulose fibers from a reaction solution through suction filtration and washing, dialyzing after washing, and collecting a nano cellulose solution;
(3) Adding sodium hydroxide solution into the solution, regulating the pH value of the solution to 7.0, adding modifier powder, and carrying out ultrasonic stirring reaction in a normal temperature environment to obtain modified nanocellulose solution; the modifier is cetyl trimethyl ammonium bromide; the mass ratio of the modifier to the nanocellulose is 1:4;
(4) Adding the obtained modified nano cellulose solution in the preparation process of the cement cementing material, uniformly stirring, pouring and molding, curing at normal temperature, demolding, and curing in a standard curing room to obtain the modified nano cellulose reinforced high-crack-resistance cement; the mixing amount of the modified nano cellulose is 0.05 to 0.2 percent of the mass of the cement.
2. The method for preparing modified nanocellulose-reinforced high-crack-resistance cement according to claim 1, wherein the cellulose pulp sheet in the step (1) is a bamboo pulp sheet; the concentration of the cellulase is 200unit/mL.
3. The method for preparing modified nanocellulose reinforced high crack resistant cement according to claim 1, wherein the mechanical stirring speed in the step (1) is 300-1000 r/min, and stirring is continued for 5 hours.
4. The method for preparing modified nanocellulose-reinforced high-crack-resistance cement according to claim 1, wherein the inactivation temperature of cellulase in the step (2) is 100 ℃ for 10min.
5. The method for preparing the modified nanocellulose-reinforced high-crack-resistance cement according to claim 1, which is characterized in that the specific process of dialysis after washing in the step (2) is as follows: repeatedly washing with water for 3 times, and dialyzing in dialysis bag for 48 hr.
6. The method for preparing the modified nanocellulose reinforced high-crack-resistance cement according to claim 1, wherein the ultrasonic power in the step (3) is 50-100W, the frequency is 50-100 kHz, and the reaction time is 3h.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102080346A (en) * | 2010-11-25 | 2011-06-01 | 山东轻工业学院 | Application of cation nano microcrystalline cellulose as paper reinforcing agent |
| JP2017025123A (en) * | 2015-07-15 | 2017-02-02 | 日本製紙株式会社 | Manufacturing method of cellulose nanofiber dispersion and dispersion method of dried chemical modified cellulose fiber |
| CN108546029A (en) * | 2018-04-19 | 2018-09-18 | 杨帮燕 | A kind of preparation method of compound fibre cement board |
| CN108752485A (en) * | 2018-06-25 | 2018-11-06 | 中国科学院青岛生物能源与过程研究所 | A kind of preparation method of the cationization nano-cellulose containing lignin |
| CN112390565A (en) * | 2020-12-02 | 2021-02-23 | 句容市星辰新型材料有限公司 | Concrete expanding agent and preparation method thereof |
| CN114149226A (en) * | 2021-12-09 | 2022-03-08 | 中国矿业大学 | Wood nano-cellulose modified cemented filling material for deep structure filling and preparation method thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US10023497B2 (en) * | 2016-06-07 | 2018-07-17 | Council Of Scientific & Industrial Research | Multifunctional material for workability of geopolymeric system and its process thereof |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102080346A (en) * | 2010-11-25 | 2011-06-01 | 山东轻工业学院 | Application of cation nano microcrystalline cellulose as paper reinforcing agent |
| JP2017025123A (en) * | 2015-07-15 | 2017-02-02 | 日本製紙株式会社 | Manufacturing method of cellulose nanofiber dispersion and dispersion method of dried chemical modified cellulose fiber |
| CN108546029A (en) * | 2018-04-19 | 2018-09-18 | 杨帮燕 | A kind of preparation method of compound fibre cement board |
| CN108752485A (en) * | 2018-06-25 | 2018-11-06 | 中国科学院青岛生物能源与过程研究所 | A kind of preparation method of the cationization nano-cellulose containing lignin |
| CN112390565A (en) * | 2020-12-02 | 2021-02-23 | 句容市星辰新型材料有限公司 | Concrete expanding agent and preparation method thereof |
| CN114149226A (en) * | 2021-12-09 | 2022-03-08 | 中国矿业大学 | Wood nano-cellulose modified cemented filling material for deep structure filling and preparation method thereof |
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