CN114477845A - Cement grinding aid and preparation method thereof - Google Patents
Cement grinding aid and preparation method thereof Download PDFInfo
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- CN114477845A CN114477845A CN202210274915.6A CN202210274915A CN114477845A CN 114477845 A CN114477845 A CN 114477845A CN 202210274915 A CN202210274915 A CN 202210274915A CN 114477845 A CN114477845 A CN 114477845A
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- 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
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
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- 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
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/38—Polysaccharides or derivatives thereof
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/0006—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid
- C08B37/0024—Homoglycans, i.e. polysaccharides having a main chain consisting of one single sugar, e.g. colominic acid beta-D-Glucans; (beta-1,3)-D-Glucans, e.g. paramylon, coriolan, sclerotan, pachyman, callose, scleroglucan, schizophyllan, laminaran, lentinan or curdlan; (beta-1,6)-D-Glucans, e.g. pustulan; (beta-1,4)-D-Glucans; (beta-1,3)(beta-1,4)-D-Glucans, e.g. lichenan; Derivatives thereof
- C08B37/0027—2-Acetamido-2-deoxy-beta-glucans; Derivatives thereof
- C08B37/003—Chitin, i.e. 2-acetamido-2-deoxy-(beta-1,4)-D-glucan or N-acetyl-beta-1,4-D-glucosamine; Chitosan, i.e. deacetylated product of chitin or (beta-1,4)-D-glucosamine; Derivatives thereof
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- 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
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/40—Surface-active agents, dispersants
- C04B2103/408—Dispersants
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- 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
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/52—Grinding aids; Additives added during grinding
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- 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
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/60—Agents for protection against chemical, physical or biological attack
- C04B2103/67—Biocides
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Abstract
The invention provides a cement grinding aid and a preparation method thereof, belonging to the technical field of cement additives. The health-care food is prepared from the following raw materials in parts by weight: 15-30 parts of polydopamine/catechol modified chitosan, 10-15 parts of sodium tripolyphosphate, 20-30 parts of industrial waste liquid and 3-10 parts of chlorinated hydrocarbon; the polydopamine/catechol modified chitosan is prepared by carrying out condensation reaction on chitosan and 3, 4-dihydroxyphenylacetic acid, and further generating polydopamine on the surface in situ. The cement grinding aid prepared by the invention can improve the early strength performance and the grinding aid effect of cement, simultaneously improve the antibacterial property, dispersity and fluidity of the cement, is more environment-friendly due to the use of industrial waste liquid, reduces the cost and has wide application prospect.
Description
Technical Field
The invention relates to the technical field of cement additives, in particular to a cement grinding aid and a preparation method thereof.
Background
In cement production, the grinding process is the link with the highest energy consumption, the energy utilization rate is extremely low, and only a small part of the process is used for increasing the specific surface area of materials. A small amount of chemical additive, namely grinding aid, is added in the grinding process, so that the grinding efficiency can be obviously improved, and the energy consumption is reduced.
The cement grinding aid is a chemical additive for improving the grinding effect and performance of cement, and is used in the grinding process of cement materials, a small amount of the grinding aid is added, so that the grinding efficiency can be obviously improved or the energy consumption can be reduced, the machine-hour yield and various technical indexes of the cement can be obviously improved, and the performance of the cement can not be damaged. As a chemical activator, the grinding aid can improve the distribution of cement particles and excite the hydration power, thereby improving the early strength and the later strength of the cement. The energy consumption of the cement industry production in China accounts for 80 percent of the energy consumption of the building material industry and 8.7 percent of the total energy consumption of the industrial production in China, and the application of the cement grinding aid brings benefits to the energy conservation and emission reduction of the cement industry and the sustainable development of the cement industry, which far exceed the value of the cement grinding aid and become an indispensable auxiliary material in the cement industry.
Chinese patent CN201210265048.6 discloses a cement grinding aid which has high material flowability in a mill, effectively reduces the over-grinding phenomenon of the mill, and improves the adhesion effect of the material on a grinding body, a lining plate and a compartment plate and the self-agglomeration phenomenon. However, the patent technology needs to use salts containing chloride ions such as sodium chloride and potassium chloride to increase the effect of the grinding aid, but the existence of the chloride ions easily causes the corrosion of steel bars in concrete and influences the service life and durability of the concrete.
Disclosure of Invention
The invention aims to provide a cement grinding aid and a preparation method thereof, which can improve the early strength performance and the grinding aid effect of cement, improve the antibacterial property, dispersity and fluidity of the cement, use industrial waste liquid to be more environment-friendly, reduce the cost and have wide application prospect.
The technical scheme of the invention is realized as follows:
the invention provides a cement grinding aid which is prepared from the following raw materials in parts by weight: 15-30 parts of polydopamine/catechol modified chitosan, 10-15 parts of sodium tripolyphosphate, 20-30 parts of industrial waste acid and 3-10 parts of chlorohydrocarbon;
the polydopamine/catechol modified chitosan is prepared by carrying out condensation reaction on chitosan and 3, 4-dihydroxyphenylacetic acid, and further generating polydopamine on the surface in situ.
As a further improvement of the invention, the preparation method of the polydopamine/catechol modified chitosan powder comprises the following steps:
s1, preparing catechol modified chitosan: dissolving chitosan in an acetic acid solution, adding an alkali solution, adjusting the pH value to be weakly acidic, adding an aqueous solution in which 3, 4-dihydroxyphenylacetic acid is dissolved into the solution, dropwise adding an activating agent solution, stirring for reaction, filtering, and washing with water to obtain catechol modified chitosan;
s2, preparing polydopamine/catechol modified chitosan: and (4) uniformly dispersing the catechol modified chitosan prepared in the step (S1) in water, adding a catalyst solution and dopamine hydrochloride, heating, stirring, reacting, filtering, and washing to obtain the polydopamine/catechol modified chitosan.
As a further improvement of the invention, the concentration of the acetic acid solution in the step S1 is 5-15 wt%; the alkali solution is NaOH, KOH or Na2CO3、K2CO3The pH is adjusted to be 5-6, and the concentration is 1-2 mol/L; the activator solution is prepared by dissolving EDC and NHS in a mass ratio of 1-2: 1-2 of ethanol aqueous solution, wherein the concentration of EDC and NHS is 2-5 wt%; the stirring reaction time is 7-12 h.
As a further improvement of the present invention, in step S1, the mass ratio of chitosan to 3, 4-dihydroxyphenylacetic acid is 100: (15-30).
As a further improvement of the invention, the catalyst solution in step S2 is Tris-HCl solution with pH value of 5-6, the heating temperature is 40-50 ℃, and the stirring reaction time is 3-5 h.
As a further improvement of the invention, in step S2, the mass ratio of the catechol-modified chitosan to the catalyst solution to the dopamine hydrochloride is 100: (2-5): (20-40).
As a further improvement of the invention, the preparation method of the polydopamine/catechol modified chitosan powder comprises the following specific steps:
s1, preparing catechol modified chitosan: dissolving 100 weight parts of chitosan in 5-15wt% acetic acid solution, and adding Na2CO3Adjusting pH value to 5-6, adding water solution containing 15-30 weight parts of 3, 4-dihydroxyphenylacetic acid into the solution, dropwise adding 30-60wt% ethanol water solution containing 0.5-1 weight part of EDC and 0.5-1 weight part of NHS, stirring for reaction for 7-12h,filtering and washing to obtain catechol modified chitosan;
s2, preparing polydopamine/catechol modified chitosan: and (2) uniformly dispersing 100 parts by weight of the catechol modified chitosan prepared in the step S1 in water, adding 2-5 parts by weight of Tris-HCl solution with the pH value of 5-6 and 20-40 parts by weight of dopamine hydrochloride, heating to 40-50 ℃, stirring for reaction for 3-5h, filtering, and washing with water to obtain the polydopamine/catechol modified chitosan.
As a further improvement of the invention, the chlorinated hydrocarbon is at least one selected from dichloromethane, 1-dichloroethane, 1, 2-dichloroethane and chloroform.
As a further improvement of the invention, the industrial waste acid is selected from at least one of industrial waste sulfuric acid, industrial waste nitric acid, industrial waste phosphoric acid and industrial waste glacial acetic acid, and the pH value of the industrial waste acid is 5-6.
The invention further provides a preparation method of the cement grinding aid, which comprises the following steps:
(1) mixing and stirring polydopamine/catechol modified chitosan and chlorohydrocarbon, heating for reflux reaction, and cooling;
(2) and (2) adding sodium tripolyphosphate and industrial waste liquid into the system in the step (1), stirring for 1-3h, and discharging to obtain the cement grinding aid.
The invention has the following beneficial effects: the chitosan has good antibacterial property, the viscosity of the chitosan can be obviously improved by introducing catechol groups into the chitosan structure, and further, polydopamine/catechol modified chitosan is obtained by generating polydopamine on the surface, the substance structure contains rich amino and hydroxyl (derived from polydopamine and chitosan), and the amino and hydroxyl can be attached to the surface of cement particles through hydrogen bond acting force, so that the surface energy of the particles is reduced or the dislocation movement of particles close to the surface layer is caused, and the defects of points or lines are generated, thereby playing a certain role in influencing the strength and hardness of the particles, and finally promoting the appearance and the expansion of cracks; the fluidity of the cement material can be improved, and adhesion is reduced;
the polydopamine/catechol modified chitosan can react with chlorohydrocarbon to obtain quaternary ammonium salt substances, so that chloride ions can be generated in the cement grinding aid without adding chloride salt, and the chloride ions can obviously enhance the early strength performance and the grinding aid effect of the cement. Meanwhile, the quaternary ammonium salt has unstable property, so that the quaternary ammonium salt formed in the constructed cement can be decomposed into polydopamine/catechol modified chitosan and chlorohydrocarbon, wherein the chlorohydrocarbon is extremely easy to volatilize, and after the construction of the cement is completed, the chloroalkane volatilizes, so that the problems of corrosion of reinforcing steel bars in the concrete, influence on the service life and durability of the concrete and the like caused by chloride ions in the concrete can be avoided;
the sodium tripolyphosphate is an amorphous water-soluble linear polyphosphate, is an inorganic surfactant, is easy to form a complex with metal cations, and when the sodium tripolyphosphate is put into a ground material, linear sodium tripolyphosphate molecules can selectively adsorb various mineral phases of cement particles and Ca exposed on the surfaces of the cement particles2+、Al3+And Fe3+The two negative O atoms extending to the outside obviously change the charged state of cement particles, so that the cement particles are negatively charged, the repulsion between the particles with the same electric property can prevent the particles from approaching and agglomerating, and simultaneously, Na+Will enter into the lattice holes or will be in contact with Ca in the lattice2+The replacement effect is generated, the distortion of mineral lattices is aggravated, and the fracture of chemical bonds in the mineral material is accelerated, so that the good grinding aiding effect is achieved.
In addition, the industrial waste liquid is added, so that the dissolution of sodium tripolyphosphate is promoted, the reaction of polydopamine/catechol modified chitosan and chlorohydrocarbon is accelerated, a good green and environment-friendly effect can be achieved, and good environment-friendly benefits are achieved.
The cement grinding aid prepared by the invention can improve the early strength performance and the grinding aid effect of cement, simultaneously improve the antibacterial property, dispersity and fluidity of the cement, is more environment-friendly due to the use of industrial waste liquid, reduces the cost and has wide application prospect.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The chitosan is purchased from Zhengzhou ultra-Van chemical Co., Ltd, the deacetylation degree content is 90%, the gray level is lower than 10%, the water content is lower than 10%, and the particle size is 100-300 meshes.
The printing and dyeing wastewater comes from Shaoxing Ming industry printing and dyeing Co., Ltd, the SS content is 800-1000mg/kg, and the chemical oxygen demand is 2000-3000 mg/L.
Example 1
The embodiment provides a preparation method of a cement grinding aid, which comprises the following steps:
(1) the preparation method of the polydopamine/catechol modified chitosan powder comprises the following steps:
s1, preparing catechol modified chitosan: dissolving 100 parts by weight of chitosan in 200 parts by weight of 10wt% acetic acid solution, then adding 1mol/L NaOH solution, adjusting the pH value to 5, adding 100 parts by weight of aqueous solution dissolved with 15 parts by weight of 3, 4-dihydroxy phenylacetic acid into the solution, dropwise adding 20 parts by weight of 30wt% ethanol aqueous solution containing 0.5 part by weight of EDC and 0.5 part by weight of NHS, stirring for reaction for 7 hours, filtering, and washing with water to obtain catechol modified chitosan;
s2, preparing polydopamine/catechol modified chitosan: adding 100 parts by weight of the catechol modified chitosan obtained in the step S1 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 30min, adding 2 parts by weight of Tris-HCl solution with the pH value of 5 and 20 parts by weight of dopamine hydrochloride, heating to 40 ℃, stirring for reaction for 3h, filtering, and washing to obtain the polydopamine/catechol modified chitosan.
(2) Mixing and stirring 15 parts by weight of polydopamine/catechol modified chitosan prepared in the step (1) and 3 parts by weight of 1, 2-dichloroethane, heating for reflux reaction, and cooling;
(3) and (3) adding 10 parts by weight of sodium tripolyphosphate and 20 parts by weight of industrial waste sulfuric acid with pH of 5 into the system in the step (2), stirring for 1h, and discharging to obtain the cement grinding aid.
Example 2
The embodiment provides a preparation method of a cement grinding aid, which comprises the following steps:
(1) the preparation method of the polydopamine/catechol modified chitosan powder comprises the following steps:
s1, preparing catechol modified chitosan: dissolving 100 parts by weight of chitosan in 200 parts by weight of 10wt% acetic acid solution, then adding 2mol/L KOH solution, adjusting the pH value to 6, adding 100 parts by weight of aqueous solution in which 30 parts by weight of 3, 4-dihydroxy phenylacetic acid is dissolved into the solution, dropwise adding 20 parts by weight of 60wt% ethanol aqueous solution containing 1 part by weight of EDC and 1 part by weight of NHS, stirring and reacting for 12 hours, filtering, and washing to obtain catechol modified chitosan;
s2, preparing polydopamine/catechol modified chitosan: adding 100 parts by weight of the catechol modified chitosan obtained in the step S1 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 30min, adding 5 parts by weight of Tris-HCl solution with the pH value of 6 and 40 parts by weight of dopamine hydrochloride, heating to 50 ℃, stirring for reaction for 5h, filtering, and washing with water to obtain the polydopamine/catechol modified chitosan.
(2) Mixing and stirring 30 parts by weight of polydopamine/catechol modified chitosan prepared in the step (1) and 10 parts by weight of dichloromethane, heating, refluxing for reaction, and cooling;
(3) and (3) adding 15 parts by weight of sodium tripolyphosphate and 30 parts by weight of industrial waste acetic acid with pH of 6 into the system in the step (2), stirring for 3 hours, and discharging to obtain the cement grinding aid.
Example 3
The embodiment provides a preparation method of a cement grinding aid, which comprises the following steps:
(1) the preparation method of the polydopamine/catechol modified chitosan powder comprises the following steps:
s1, preparing catechol modified chitosan: dissolving 100 parts by weight of chitosan in 200 parts by weight of 10wt% acetic acid solution, then adding 1.5mol/L NaOH solution, adjusting the pH value to 5.5, adding 100 parts by weight of aqueous solution dissolved with 22 parts by weight of 3, 4-dihydroxy phenylacetic acid into the solution, dropwise adding 20 parts by weight of 45wt% ethanol aqueous solution containing 0.7 part by weight of EDC and 0.7 part by weight of NHS, stirring and reacting for 10 hours, filtering, and washing with water to obtain catechol-modified chitosan;
s2, preparing polydopamine/catechol modified chitosan: adding 100 parts by weight of the catechol modified chitosan obtained in the step S1 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 30min, adding 3.5 parts by weight of Tris-HCl solution with the pH value of 5.5 and 30 parts by weight of dopamine hydrochloride, heating to 45 ℃, stirring for reaction for 4h, filtering, and washing with water to obtain the polydopamine/catechol modified chitosan.
(2) Mixing and stirring 22 parts by weight of polydopamine/catechol modified chitosan prepared in the step (1) and 7 parts by weight of 1, 1-dichloroethane, heating for reflux reaction, and cooling;
(3) and (3) adding 15 parts by weight of sodium tripolyphosphate and 25 parts by weight of industrial waste sulfuric acid with pH of 5 into the system in the step (2), stirring for 2 hours, and discharging to obtain the cement grinding aid.
Comparative example 1
Compared with the example 3, the chitosan is not modified by catechol, and other conditions are not changed.
The embodiment provides a preparation method of a cement grinding aid, which comprises the following steps:
(1) preparing polydopamine modified chitosan: adding 100 parts by weight of chitosan into 200 parts by weight of water, carrying out ultrasonic dispersion at 1000W for 30min, adding 3.5 parts by weight of Tris-HCl solution with the pH value of 5.5 and 30 parts by weight of dopamine hydrochloride, heating to 45 ℃, carrying out stirring reaction for 4h, filtering, and washing with water to obtain the polydopamine modified chitosan.
(2) Mixing and stirring 22 parts by weight of the modified chitosan prepared in the step (1) and 7 parts by weight of 1, 1-dichloroethane, heating for reflux reaction, and cooling;
(3) and (3) adding 15 parts by weight of sodium tripolyphosphate and 40 parts by weight of industrial waste sulfuric acid with pH of 5 into the system in the step (2), stirring for 2 hours, and discharging to obtain the cement grinding aid.
Comparative example 2
Compared with example 3, chitosan was not modified with polydopamine, and other conditions were not changed.
The embodiment provides a preparation method of a cement grinding aid, which comprises the following steps:
(1) the preparation method of the catechol modified chitosan powder comprises the following steps:
preparing catechol modified chitosan: dissolving 100 parts by weight of chitosan in 200 parts by weight of 17wt% acetic acid solution, then adding 1.5mol/L NaOH solution, adjusting the pH value to 5.5, adding 100 parts by weight of aqueous solution dissolved with 22 parts by weight of 3, 4-dihydroxy phenylacetic acid into the solution, dropwise adding 20 parts by weight of 45wt% ethanol aqueous solution containing 0.7 part by weight of EDC and 0.7 part by weight of NHS, stirring and reacting for 10 hours, filtering, and washing with water to obtain the catechol modified chitosan.
(2) Mixing and stirring 22 parts by weight of the modified chitosan prepared in the step (1) and 7 parts by weight of 1, 1-dichloroethane, heating for reflux reaction, and cooling;
(3) and (3) adding 15 parts by weight of sodium tripolyphosphate and 40 parts by weight of industrial waste sulfuric acid with pH of 5 into the system in the step (2), stirring for 2 hours, and discharging to obtain the cement grinding aid.
Comparative example 3
Compared with example 3, 1-dichloroethane was not added in step (3), and other conditions were not changed.
Comparative example 4
Compared with example 3, the polydopamine/catechol modified chitosan was replaced by unmodified chitosan, and other conditions were not changed.
Comparative example 5
Compared with the example 3, the sodium tripolyphosphate is not added in the step (3), and other conditions are not changed.
Test example
Test objects: the cement grinding aids prepared in examples 1-3 and comparative examples 1-5 of the invention.
The test method comprises the following steps:
the formula of the cement raw materials comprises the following components in percentage by mass: 55% of cement clinker, 5% of gypsum, 21% of limestone, 10% of fly ash, 2% of manganese slag and 7% of furnace bottom slag.
The mixing amount of the cement grinding aid is 0.02 percent.
The cement preparation method comprises the following steps: respectively drying limestone, fly ash, manganese slag and furnace bottom slag, grinding, mixing, placing into a rotary kiln, sintering at 1300 ℃ for 45min, taking out of the kiln, cooling in air to obtain a mixture, mixing the mixture with cement clinker, crushing, adding gypsum, and jointly grinding for 1h to obtain the cement.
The fineness test is carried out according to GB/T1345-.
The results are shown in tables 1 and 2.
TABLE 1
TABLE 2
As can be seen from the table above, the cement grinding aid prepared by the embodiment of the invention can obviously improve the specific surface area of cement particles, reduce the fineness of the cement particles and obviously improve the early strength performance and the mechanical property of cement.
Compared with the example 3, the chitosan of the comparative examples 1 and 2 is not modified by catechol or polydopamine, so that the cement fineness is improved, the specific surface area is reduced, the setting time is reduced, and the mechanical property is reduced. The chitosan has good antibacterial property, the viscosity of the chitosan can be obviously improved by introducing catechol groups into the chitosan structure, and further, polydopamine/catechol modified chitosan is obtained by generating polydopamine on the surface, the substance structure contains rich amino and hydroxyl (derived from polydopamine and chitosan), and the amino and hydroxyl can be attached to the surface of cement particles through hydrogen bond acting force, so that the surface energy of the particles is reduced or the dislocation movement of particles close to the surface layer is caused, and the defects of points or lines are generated, thereby playing a certain role in influencing the strength and hardness of the particles, and finally promoting the appearance and the expansion of cracks; the fluidity of the cement material can be improved, and the adhesion is reduced.
Compared with the example 3, the cement of the comparative examples 3 and 4 has improved fineness, reduced specific surface area and reduced early strength performance without adding chloroalkane. The polydopamine/catechol modified chitosan can react with chlorohydrocarbon to obtain quaternary ammonium salt substances, so that chloride ions can be generated in the cement grinding aid without adding chloride salt, and the chloride ions can obviously enhance the early strength performance and the grinding aid effect of the cement. Meanwhile, the quaternary ammonium salt has unstable property, so that the quaternary ammonium salt formed in the constructed cement can be decomposed into polydopamine/catechol modified chitosan and chlorohydrocarbon, wherein the chlorohydrocarbon is extremely easy to volatilize, and after the construction of the cement is completed, the chloroalkane volatilizes, so that the problems that reinforcing steel bars in the concrete are corroded due to chloride ions in the concrete, the service life and the durability of the concrete are influenced and the like are solved.
Compared with the embodiment 3, the polydopamine/catechol modified chitosan is replaced by the unmodified chitosan, so that the cement fineness is improved, the specific surface area is reduced, and the early strength performance is reduced. According to the invention, a catechol group is introduced into a chitosan structure, so that the viscosity of chitosan can be obviously improved, and further, polydopamine/catechol modified chitosan is obtained by generating polydopamine on the surface, and the substance structure contains abundant amino and hydroxyl (derived from polydopamine and chitosan), and can be attached to the surface of cement particles through hydrogen bond acting force, so that the surface energy of the particles is reduced or the dislocation movement of particles close to the surface layer is caused, and the defects of points or lines are generated, thereby playing a certain role in influencing the strength and hardness of the particles, and finally promoting the appearance and the expansion of cracks; the fluidity of the cement material can be improved, and the adhesion is reduced.
Comparative example 5 compared with example 3, the fineness of the cement is improved and the specific surface area is reduced without adding sodium tripolyphosphate, which is an amorphous water-soluble linear polyphosphate, is an inorganic surfactant and is easy to form a complex with metal cations, when the sodium tripolyphosphate is put into the ground material, linear sodium tripolyphosphate molecules can selectively adsorb mineral phases of cement particles and Ca exposed on the surfaces of the cement particles2+、Al3+And Fe3+The two negative O atoms extending to the outside obviously change the charged state of cement particles, so that the cement particles are negatively charged, the repulsion between the particles with the same electric property can prevent the particles from approaching and agglomerating, and simultaneously, Na+Will enter into the lattice holes or will be in contact with Ca in the lattice2+The replacement effect is generated, the distortion of mineral lattices is aggravated, and the fracture of chemical bonds in the mineral material is accelerated, so that the good grinding aiding effect is achieved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. The cement grinding aid is characterized by being prepared from the following raw materials in parts by weight: 15-30 parts of polydopamine/catechol modified chitosan, 10-15 parts of sodium tripolyphosphate, 20-30 parts of industrial waste acid and 3-10 parts of chlorohydrocarbon;
the polydopamine/catechol modified chitosan is prepared by carrying out condensation reaction on chitosan and 3, 4-dihydroxyphenylacetic acid, and further generating polydopamine on the surface in situ.
2. The cement grinding aid as claimed in claim 1, wherein the polydopamine/catechol modified chitosan powder is prepared by the following method:
s1, preparing catechol modified chitosan: dissolving chitosan in an acetic acid solution, adding an alkali solution, adjusting the pH value to be weakly acidic, adding an aqueous solution in which 3, 4-dihydroxyphenylacetic acid is dissolved into the solution, dropwise adding an activating agent solution, stirring for reaction, filtering, and washing with water to obtain catechol modified chitosan;
s2, preparing polydopamine/catechol modified chitosan: and (4) uniformly dispersing the catechol modified chitosan prepared in the step (S1) in water, adding a catalyst solution and dopamine hydrochloride, heating, stirring, reacting, filtering, and washing to obtain the polydopamine/catechol modified chitosan.
3. The cement grinding aid as claimed in claim 2, wherein the concentration of the acetic acid solution in step S1 is 5-15 wt%; the alkali solution is NaOH, KOH or Na2CO3、K2CO3The pH is adjusted to be 5-6, and the concentration is 1-2 mol/L; the activator solution is prepared by dissolving EDC and NHS in a mass ratio of 1-2: 1-2 of ethanol aqueous solution, wherein the concentration of EDC and NHS is 2-5 wt%; the stirring reaction time is 7-12 h.
4. The cement grinding aid as claimed in claim 2, wherein the mass ratio of the chitosan to the 3, 4-dihydroxyphenylacetic acid in step S1 is 100: (15-30).
5. The cement grinding aid as claimed in claim 2, wherein the catalyst solution in step S2 is Tris-HCl solution with pH value of 5-6, the heating temperature is 40-50 ℃, and the stirring reaction time is 3-5 h.
6. The cement grinding aid as claimed in claim 2, wherein the mass ratio of the catechol-modified chitosan to the catalyst solution to the dopamine hydrochloride in step S2 is 100: (2-5): (20-40).
7. The cement grinding aid as claimed in claim 2, wherein the preparation method of the polydopamine/catechol modified chitosan powder comprises the following steps:
s1, preparing catechol modified chitosan: dissolving 100 weight parts of chitosan in 5-15wt% acetic acid solution, and adding Na2CO3Adjusting the pH value of the aqueous solution to 5-6, adding the aqueous solution dissolved with 15-30 parts by weight of 3, 4-dihydroxyphenylacetic acid into the aqueous solution, dropwise adding 30-60wt% ethanol aqueous solution containing 0.5-1 part by weight of EDC and 0.5-1 part by weight of NHS, stirring for reaction for 7-12h, filtering, and washing to obtain catechol modified chitosan;
s2, preparing polydopamine/catechol modified chitosan: and (2) uniformly dispersing 100 parts by weight of the catechol modified chitosan prepared in the step S1 in water, adding 2-5 parts by weight of Tris-HCl solution with the pH value of 5-6 and 20-40 parts by weight of dopamine hydrochloride, heating to 40-50 ℃, stirring for reaction for 3-5h, filtering, and washing with water to obtain the polydopamine/catechol modified chitosan.
8. The cement grinding aid according to claim 1, wherein the chlorinated hydrocarbon is selected from at least one of dichloromethane, 1-dichloroethane, 1, 2-dichloroethane, and chloroform.
9. The cement grinding aid as claimed in claim 1, wherein the industrial waste acid is selected from at least one of industrial waste sulfuric acid, industrial waste nitric acid, industrial waste phosphoric acid and industrial waste glacial acetic acid, and the pH of the industrial waste acid is 5-6.
10. A method of preparing a cement grinding aid as claimed in any one of claims 1 to 9 comprising the steps of:
mixing and stirring polydopamine/catechol modified chitosan and chlorohydrocarbon, heating for reflux reaction, and cooling;
(2) and (2) adding sodium tripolyphosphate and industrial waste liquid into the system in the step (1), stirring for 1-3h, and discharging to obtain the cement grinding aid.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113292267A (en) * | 2021-01-15 | 2021-08-24 | 云南森博混凝土外加剂有限公司 | Malt syrup retarder and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105271880A (en) * | 2015-11-19 | 2016-01-27 | 杭州立平工贸有限公司 | Cement grinding aid |
| CN108516725A (en) * | 2018-03-22 | 2018-09-11 | 徐州巨龙新材料科技有限公司 | A kind of retardation setting type cement grinding aid |
| CN111821516A (en) * | 2020-05-07 | 2020-10-27 | 广州贝奥吉因生物科技股份有限公司 | Adhesive conductive hydrogel and preparation method and application thereof |
| CN113816630A (en) * | 2021-10-13 | 2021-12-21 | 广州基业长青新材料有限公司 | Cement grinding aid and preparation method and application thereof |
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2022
- 2022-03-21 CN CN202210274915.6A patent/CN114477845A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105271880A (en) * | 2015-11-19 | 2016-01-27 | 杭州立平工贸有限公司 | Cement grinding aid |
| CN108516725A (en) * | 2018-03-22 | 2018-09-11 | 徐州巨龙新材料科技有限公司 | A kind of retardation setting type cement grinding aid |
| CN111821516A (en) * | 2020-05-07 | 2020-10-27 | 广州贝奥吉因生物科技股份有限公司 | Adhesive conductive hydrogel and preparation method and application thereof |
| CN113816630A (en) * | 2021-10-13 | 2021-12-21 | 广州基业长青新材料有限公司 | Cement grinding aid and preparation method and application thereof |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113292267A (en) * | 2021-01-15 | 2021-08-24 | 云南森博混凝土外加剂有限公司 | Malt syrup retarder and preparation method and application thereof |
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