CN115180866B - Hydration heat regulation type magnesium high-efficiency anti-cracking agent and preparation method thereof - Google Patents
Hydration heat regulation type magnesium high-efficiency anti-cracking agent and preparation method thereof Download PDFInfo
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- CN115180866B CN115180866B CN202210788849.4A CN202210788849A CN115180866B CN 115180866 B CN115180866 B CN 115180866B CN 202210788849 A CN202210788849 A CN 202210788849A CN 115180866 B CN115180866 B CN 115180866B
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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
Abstract
The invention discloses a hydration heat regulation type magnesian high-efficiency anti-cracking agent and a preparation method thereof, belonging to the technical field of concrete additives. The paint comprises the following components in percentage by mass: 50-80% of expansion component, 1-5% of hydration heat adjusting component, 1-5% of shrinkage reducing component and 10-45% of reinforcing component; the hydration heat regulation type magnesium high-efficiency anti-cracking agent disclosed by the invention has the advantages that the expansion component compensates shrinkage, the hydration heat regulation component reduces temperature shrinkage, the shrinkage reducing component reduces concrete self-shrinkage, the reinforcing component strengthens a matrix, the temperature shrinkage and self-shrinkage of the concrete are effectively reduced, the full-period compensation shrinkage is realized, the mechanical property of the concrete is improved, and the anti-cracking property of the concrete is comprehensively improved from the two aspects of anti-cracking and reinforcing.
Description
Technical Field
The invention belongs to the technical field of concrete additives, and particularly relates to a hydration heat regulation type magnesium high-efficiency anti-cracking agent and a preparation method thereof.
Background
The concrete is used as a high-strength material which is cheap and easy to obtain, good in plasticity and strong in durability, and is widely applied to the fields of public buildings, civil buildings, traffic, water conservancy and hydropower, nuclear power and the like. However, the engineering application of high-performance concrete for decades shows that shrinkage cracking is the biggest defect of the current concrete structure, and for this reason, novel anti-cracking materials, construction methods, maintenance measures and the like are continuously developed and applied.
The expanding agent is used as a common anti-cracking material, and the expanding agent generates crystals in the hydration process to generate volume expansion, so that the effect of compensating concrete shrinkage is achieved, and the risk of structural cracking is reduced. The existing concrete expanding agent mainly comprises a calcium expanding agent and a magnesium expanding agent, wherein the calcium expanding agent comprises calcium oxide and calcium oxide-calcium sulphoaluminate, the problems of high hydration reaction, large water demand, unstable hydration products and the like exist in the using process, when the application environment temperature exceeds 40 ℃, the volume expansion of the material mainly occurs in the early stage, and particularly, the invalid expansion generated in the concrete plastic stage cannot compensate the later-stage shrinkage of the concrete. As for the magnesium expanding agent, the magnesium expanding agent is mainly magnesia obtained by burning magnesite at 900-1100 ℃, and is widely applied due to long hydration period, adjustable expansion process and stable properties of hydration products, but the defects are that the magnesium expanding agent has small early expansion energy, cannot well compensate early contraction and has long later expansion time in an environment of less than 40 ℃, and the volume stability problem of a concrete structure can be caused. Based on the above problems, there is a need to develop a novel anti-cracking product with controllable expansion process, long hydration period, and good compensation shrinkage effect in early and later stages.
The expansion agent is used for compensating the shrinkage of the concrete, which is one of effective ways for preventing the shrinkage cracking of the concrete, but because the concrete has large volume, the hydration reaction of the cement can generate a large amount of hydration heat, the hydration heat is released in a concentrated manner, the internal temperature of the concrete is continuously raised, the internal and external temperature differences are formed on the surface and inside of the concrete, and when the tensile stress generated by the internal and external temperature differences at the initial stage of the concrete setting exceeds the compressive strength of the concrete, the concrete cracks can be caused; in order to reduce the cracking risk, the internal and external temperature difference must be effectively reduced, so that the hydration process of cement needs to be regulated and controlled, the hydration speed of the cement in the acceleration period is reduced as much as possible, heat generated by cement hydration does not need to be released in a centralized manner, time is won for concrete heat dissipation, the internal and external temperature difference is reduced, and the cracking risk of the concrete is further remarkably reduced.
Chinese patent CN 109293266A discloses a hydration heat inhibited type expansion fiber composite anti-cracking agent, which comprises the following components in percentage by mass: 93.5 to 98 percent of expansion component; 1.5 to 6 percent of hydration heat inhibiting component; 0.5 to 1.5 percent of basalt fiber; wherein, the expansion component is formed by compounding a light-burned magnesia expansion agent and a calcium expansion agent according to the mass ratio of 1; the hydration heat inhibiting component is compounded by an ester compound and a retarder according to the mass ratio of 1-5. The anti-cracking agent can effectively reduce the temperature rise of the hydration reaction of the concrete, can compensate shrinkage from the early stage and the middle and later stages of the concrete, obviously reduces the temperature crack of the concrete, and enhances the anti-cracking performance of the concrete. However, the anti-cracking agent has limited effect of improving the expansion rate of mortar limitation and also has limited effect of reducing the hydration heat of cement; and the hydration heat inhibiting component contains a retarder, so that the normal hydration process of the concrete is influenced while the temperature peak of the concrete is reduced, the setting time of the concrete is long, and the early strength of the concrete is low.
Based on the technical scheme, on the basis of comprehensively solving the problem of concrete cracking through expansion compensation shrinkage and hydration heat regulation, a hydration heat regulation type magnesium efficient anti-cracking agent is developed, the expansion effect of an expansion component and the hydration heat inhibition effect of a hydration heat regulation component are improved, and the urgent need of improving the quality of construction engineering is to comprehensively and effectively reduce the cracking risk of a concrete structure from the action mechanisms of reducing the temperature shrinkage, self-shrinkage, drying shrinkage, matrix reinforcement and the like of the concrete.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a hydration heat adjustable magnesium-based efficient crack-resistant agent, which can improve the crack resistance of a concrete structure from the aspects of reducing temperature shrinkage, reducing self-shrinkage, compensating shrinkage, enhancing the strength of a matrix, and the like, and solve the cracking problem of a concrete structure.
In order to achieve the purpose, the specific technical scheme of the invention is as follows:
the hydration heat regulation type magnesium high-efficiency anti-cracking agent comprises the following components in percentage by mass: 50-80% of expansion component, 1-5% of hydration heat regulating component, 1-5% of shrinkage reducing component and 10-45% of reinforcing component;
the preparation method of the expansion component comprises the following steps:
s1, uniformly mixing magnesium oxide and ammonium chloride, and adding water for granulation to obtain granules;
s2, calcining the particles obtained in the step S1 at 350-550 ℃, cooling, and grinding to obtain powder;
s3, mixing the powder obtained in the step S2 with activated carbon powder, and then slowly adding an acid solution in a spray form under the conditions of water bath heating and stirring to obtain the expansion component;
the preparation method of the hydration heat regulating component comprises the following steps: heating starch to 130-200 ℃, preserving heat for 1-2 h, and cooling to room temperature; and then dispersing the heated starch in a gluconic acid solution, performing ultrasonic dispersion for 5-7 h, standing, separating, washing, drying and grinding to obtain the hydration heat regulation component.
The hydration heat regulation type magnesium high-efficiency anti-cracking agent disclosed by the invention has the advantages that the expansion component compensates shrinkage, the hydration heat regulation component reduces temperature shrinkage, the shrinkage reduction component reduces concrete self-shrinkage, and the reinforcement component strengthens the matrix strength, so that the anti-cracking property of a concrete structure is comprehensively improved from the four aspects. The expansion component is a modified magnesium oxide expansion agent, and after acidification treatment, the growth environment of hydrated crystals of magnesium oxide in concrete can be improved, the early compensation shrinkage capacity of the magnesium oxide expansion agent is improved, the later compensation shrinkage capacity of the magnesium oxide expansion agent is not weakened, and the continuous expansion effect of the magnesium oxide expansion agent is utilized to play a full-period compensation shrinkage role, so that the problem that the early expansion energy of the current magnesium oxide expansion agent is insufficient in the application process is solved. During calcination, the ammonium chloride is decomposed into ammonia gas and chlorine gas, so that the porosity of the magnesium oxide can be improved, more active sites are generated, and the subsequent acidification treatment is facilitated. The active carbon has the main function of accelerating the capture of sprayed acidic substances by utilizing the strong adsorption effect of the active carbon, so that the acidification and modification of the magnesium oxide are more smooth.
The hydration heat regulating component is formed by modifying starch through a gluconic acid solution, the hydration heat regulating component has a large amount of hydroxyl groups through modification treatment, has good adaptability with cement, and has the effect of obviously inhibiting hydration heat release rate in a cement hydration acceleration period; the hydration heat regulating component can not only reduce the temperature shrinkage of a concrete structure, but also improve the compensation shrinkage capacity of the expansion component. The purpose of heating the starch is to decompose the starch to form a smaller molecular structure and generate more hydroxyl groups, and then the starch is modified by using a gluconic acid solution to further increase the number of the hydroxyl groups.
Preferably, the shrinkage reducing component comprises the following components in percentage by mass: 15-40% of ethylene glycol, 40-60% of polyoxypropylene glycol and 10-25% of 3-aminopropanol. The shrinkage reducing component can obviously reduce the surface tension of an alkaline solution, and tests the self-shrinkage performance of a concrete test piece, and data show that the effect of reducing the self-shrinkage of the concrete by compounding the ethylene glycol, the polyoxypropylene glycol and the 3-aminopropanol is far better than that of a single component, and the optimal effect of reducing the self-shrinkage of the concrete can be achieved only when the dosage ratio of the ethylene glycol, the polyoxypropylene glycol and the 3-aminopropanol is within the limited range of the invention.
Preferably, the reinforcing component comprises the following components in percentage by mass: 5 to 20 percent of sodium bicarbonate, 55 to 80 percent of superfine mineral powder, 5 to 30 percent of anhydrite and 0.002 to 0.02 percent of hydroxypropyl methyl cellulose ether. The reinforcing component mainly plays a role in activating, promoting temperature suppression effect and enhancing compactness; the reinforcing component generates more hydration products in the hydration process, can make up the influence of the hydration heat regulating component on the early strength of the concrete, and further promotes the development of the later strength of the concrete; the reinforcing component and the expansion component can also synergistically play a role in compensating shrinkage, so that the crack resistance and the durability of concrete are further improved, and meanwhile, the weak-base sodium bicarbonate can promote the temperature inhibition effect of the hydration heat regulation component, improve the temperature inhibition rate and shorten the setting time.
Preferably, in step S3, the acid solution is 20% by weight, and the acid includes at least one of acetic acid, malic acid, citric acid, tartaric acid, or tannic acid.
Preferably, the starch comprises at least one of sweet potato starch, water chestnut starch, corn starch, lotus root starch or pea starch.
Preferably, the washing is carried out by repeating washing and filtration of the precipitate obtained after the separation until the pH of the solution is 5.0 to 7.0.
Preferably, the specific surface area of the hydration heat regulating component obtained after grinding is 200 to 300m 2 /kg。
Preferably, the specific surface area of the superfine mineral powder is 800-1000 m 2 Kg, SO in anhydrite 3 The content of the hydroxypropyl methyl cellulose is more than or equal to 45 weight percent, and the viscosity of the hydroxypropyl methyl cellulose is 10 ten thousand.
The invention also aims to provide a preparation method of the hydration heat regulation type magnesium high-efficiency anti-cracking agent, which comprises the following steps: mixing the expansion component, the hydration heat regulating component and the reinforcing component according to a proportion, and adding the shrinkage reducing component in a spraying mode in the mixing and stirring process to obtain the hydration heat regulating type magnesium high-efficiency anti-cracking agent.
Compared with the prior art, the invention has the advantages that:
(1) The hydration heat regulation type magnesium high-efficiency anti-cracking agent disclosed by the invention has the advantages that the expansion component compensates shrinkage, the hydration heat regulation component reduces temperature shrinkage, the shrinkage reducing component reduces concrete self-shrinkage, the reinforcing component strengthens a matrix, the temperature shrinkage and self-shrinkage of the concrete are effectively reduced, the full-period compensation shrinkage is realized, the mechanical property of the concrete is improved, and the anti-cracking property of the concrete is comprehensively improved from the two aspects of anti-cracking and reinforcing.
(2) The magnesium oxide expanding agent is subjected to acidification treatment, so that the growth environment of hydrated crystals of magnesium oxide in concrete can be improved, the early compensation shrinkage capacity of the magnesium oxide can be improved, the later compensation shrinkage capacity of the magnesium oxide can not be weakened, the magnesium oxide expanding agent can be used for sustainably compensating the shrinkage of the concrete, and the full-period compensation shrinkage effect can be achieved, so that the problem that the early expansion capacity of the existing magnesium oxide expanding agent is insufficient in the application process can be solved.
(3) The hydration heat adjusting component obtained by modifying the starch by using the gluconic acid solution has a large amount of hydroxyl groups, has good adaptability with cement, and has the effect of obviously inhibiting hydration heat release rate in the cement hydration acceleration period; meanwhile, the hydration heat adjusting component has polyhydroxy which can effectively reduce the alkalinity of cement slurry around magnesium oxide, is beneficial to promoting the growth of magnesium hydroxide crystals and promoting the release of expansion energy; the hydration heat regulating component can not only reduce the temperature shrinkage of a concrete structure, but also improve the compensation shrinkage capacity of the expansion component.
(4) The shrinkage reducing component compounded by the ethylene glycol, the polyoxypropylene diol and the 3-aminopropanol can effectively reduce the self-shrinkage of the concrete.
(5) The sodium bicarbonate in the reinforcing component can promote the temperature inhibiting effect of the hydration heat regulating component, improve the temperature inhibiting rate and shorten the condensation time.
Drawings
FIG. 1 shows the free deformation of a concrete specimen.
Detailed Description
The technical solutions of the present invention will be described clearly and completely below, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.
In the following examples and comparative examples, the starch is selected from one or more of sweet potato starch, water chestnut starch, corn starch, lotus root starch or pea starch; the specific surface area of the superfine mineral powder is 800-1000 m 2 Per kg SO in anhydrite 3 The content of the hydroxypropyl methyl cellulose is more than or equal to 45 weight percent, and the viscosity of the hydroxypropyl methyl cellulose is 10 ten thousand.
Example 1
The embodiment provides a hydration heat regulation type magnesium high-efficiency anti-cracking agent which comprises the following components in percentage by mass: 60% of expansion component, 3% of hydration heat adjusting component, 3% of shrinkage reducing component and 34% of reinforcing component;
the preparation method of the expansion component comprises the following steps:
s1, adding magnesium oxide and ammonium chloride into a V-shaped mixer according to a mass ratio of 10; then adding water with the mass being 20% of the total mass of the magnesium oxide and the ammonium chloride, and granulating by using a disc granulator to obtain balls with the particle size of 3-5 mm;
s2, placing the ball obtained in the step S1 in a muffle furnace, heating to 500 ℃ at a heating rate of 2 ℃/min, preserving heat for 30min, naturally cooling to room temperature, and grinding until the specific surface area is 300-400 m 2 Per kg, obtaining modified magnesium oxide powder;
s3, pouring the modified magnesium oxide powder obtained in the step S2 and activated carbon powder with the fineness of 200 meshes into a container according to the mass ratio of 100;
the preparation method of the hydration heat regulating component comprises the following steps:
p1, placing starch in a muffle furnace, heating to 150 ℃ at the heating rate of 1 ℃/min, preserving heat for 1h, and naturally cooling to room temperature;
p2, dispersing the heated starch in a gluconic acid solution with the mass fraction of 10% according to the mass ratio of 1; discarding the supernatant, repeatedly cleaning and filtering the precipitate until the pH value of the solution is 7.0, and then placing the solution in a vacuum drying oven to dry the solution to constant weight at 40-60 ℃ to obtain solid particles;
p3, grinding the solid particles obtained in the step P2 to a specific surface area of 200-300 m in a vibration grinding mode 2 The heat-eliminating regulating component is obtained after the reaction is carried out for every kg.
The shrinkage reducing component comprises the following components in percentage by mass: 35% of ethylene glycol, 50% of polyoxypropylene glycol and 15% of 3-aminopropanol;
the reinforcing component comprises the following components in percentage by mass: 8% of sodium bicarbonate, 79.99% of superfine mineral powder, 12% of anhydrite and 0.01% of hydroxypropyl methyl cellulose ether.
The embodiment also provides a preparation method of the hydration heat regulation type magnesium high-efficiency anti-cracking agent, which comprises the following steps: mixing the expansion component, the hydration heat regulating component and the reinforcing component according to the proportion, and adding the shrinkage reducing component in a spraying mode in the mixing and stirring process to obtain the hydration heat regulating type magnesium high-efficiency anti-cracking agent.
Example 2
This embodiment is substantially the same as embodiment 1 except that: the hydration heat regulation type magnesium high-efficiency anti-cracking agent comprises the following components in percentage by mass: 80% of expansion component, 3% of hydration heat adjusting component, 3% of shrinkage reducing component and 14% of reinforcing component;
in step S3 of the method for preparing the swelling component, a citric acid solution having a mass fraction of 20% is slowly added in the form of spray.
Example 3
This embodiment is substantially the same as embodiment 1 except that: the hydration heat regulation type magnesium efficient anti-cracking agent comprises the following components in percentage by mass: 50% of expansion component, 3% of hydration heat adjusting component, 3% of shrinkage reducing component and 44% of reinforcing component;
in step S3 of the method for preparing the swelling component, a 20% by mass of a solution of melittic acid is slowly added in the form of a spray.
Example 4
This embodiment is substantially the same as embodiment 1 except that: the hydration heat regulation type magnesium high-efficiency anti-cracking agent comprises the following components in percentage by mass: 60% of expansion component, 1% of hydration heat adjusting component, 5% of shrinkage reducing component and 34% of reinforcing component;
in step S3 of the method for preparing the swelling component, a tannic acid solution having a mass fraction of 20% is slowly added in the form of spray.
Example 5
The embodiment is basically the same as the embodiment 1, and the hydration heat regulation type magnesium high-efficiency anti-cracking agent comprises the following components in percentage by mass: 60% of expansion component, 5% of hydration heat adjusting component, 1% of shrinkage reducing component and 34% of reinforcing component.
Example 6
The present embodiment is substantially the same as embodiment 1, and the shrinkage reducing component of the present embodiment comprises the following components in percentage by mass: 15% of ethylene glycol, 60% of polyoxypropylene glycol and 25% of 3-aminopropanol.
Comparative example 1
This comparative example is essentially the same as example 1, except that: the hydration heat regulating component of this comparative example was unmodified starch.
Comparative example 2
Comparative example 2 is substantially the same as example 1 except that: the intumescent component of this comparative example is an unmodified magnesia intumescent agent.
Comparative example 3
Comparative example 3 is substantially the same as example 1 except that: the hydration heat regulating type high-efficiency magnesium anti-cracking agent of the comparative example does not contain hydration heat regulating components and is replaced by inert limestone powder.
Comparative example 4
Comparative example 4 is substantially the same as example 1 except that: the hydration heat regulating type magnesian high-efficiency anticracking agent of the comparative example does not contain an expansion component and is replaced by inert limestone powder.
Comparative example 5
Comparative example 5 is substantially the same as example 1 except that: the hydration heat regulating type magnesium high-efficiency anti-cracking agent of the comparative example does not contain a reinforcing component and is replaced by inert limestone powder.
Comparative example 6
Comparative example 6 is substantially the same as example 1 except that: the shrinkage reducing component of this comparative example contained no 3-aminopropanol and was replaced by distilled water.
Comparative example 7
Comparative example 7 is substantially the same as example 1 except that: the reinforcing component of this comparative example contained no sodium bicarbonate and was replaced with the inert material limestone powder.
Test examples
The hydration heat-regulated magnesium high-efficiency crack resistance agents of examples 1 to 6 and comparative examples 1 to 7 were subjected to performance tests.
(1) Semi-adiabatic temperature rise test of cement paste
The hydration heat regulating type magnesium high-efficiency crack resistance agents of the examples 1 to 6 and the comparative examples 1 to 7 are mixed into the cement paste according to the following mixing ratio: 1900 parts of reference cement, 760 parts of water and 114 parts of hydration heat regulation type high-efficiency magnesia anti-cracking agent, and the semi-adiabatic temperature rise of the cement paste is tested according to the group standard concrete temperature-inhibiting anti-cracking waterproofing agent, and the test results are shown in Table 1.
TABLE 1 Cement paste semi-adiabatic temperature rise test results
The test results in table 1 show that when the hydration heat adjustment type magnesium high-efficiency anti-cracking agent is added, the semi-adiabatic temperature rise temperature-restraining rate of the cement paste can exceed 40%, the delay time of the temperature rise at 5 ℃ is within 8h, and the delay time is not more than 4h compared with that of a blank group, so that the anti-cracking agent disclosed by the invention can not only well reduce the temperature shrinkage of concrete, but also can not cause the obvious retardation phenomenon of the concrete, and can not cause the safety problem. By comparing example 1 with comparative example 1, it can be seen that the temperature inhibition rate of starch after acid modification is increased from 1.5% to 56.6%, and the enhancement effect is significant. By comparing example 1 with comparative example 7, it can be found that the reinforcing component of comparative example 7 does not contain sodium bicarbonate, the temperature suppression rate is reduced, the delay time of temperature rise at 5 ℃ is lengthened, and it is demonstrated that sodium bicarbonate can promote the temperature suppression effect of the hydration heat regulating component, improve the temperature suppression rate, and shorten the setting time.
(2) Mortar restrained expansion property test
According to the relevant regulations of CBMF19-2017 magnesium oxide expanding agent for concrete, the mixing ratio is as follows: 450 parts of reference cement, 270 parts of water, 1350 parts of standard sand and 45 parts of hydration heat adjustment type high-efficiency magnesia crack resistance agent, the molded mortar test piece is cured in water at 40 ℃, the limited expansion rate of each age is tested, and the test results are shown in table 2.
TABLE 2 mortar Limited expansion Rate%
The test results in Table 2 show that when the hydration heat regulation type magnesia high-efficiency anti-cracking agent is doped into the hydration heat regulation type magnesia, the 3d expansion rate of a mortar test piece exceeds 0.02 percent and the 28d expansion rate exceeds 0.06 percent under the water culture at 40 ℃, and the mortar test piece still continuously increases within 120d, which shows that the anti-cracking agent can play a role in long-term compensation shrinkage. By comparing example 1 and comparative example 2, it can be seen that the early swelling energy is significantly improved by acidifying the modified magnesium oxide. By comparing the example 1 with the comparative example 3, the fact that the hydration heat regulating component and the expansion component are compounded can obviously improve the early expansion rate of the expansion component, and the later expansion amount is improved to a certain extent, shows that the hydration heat regulating component can not only reduce the temperature shrinkage of a concrete structure, but also improve the compensation shrinkage capacity of the expansion component, and has good synergistic effect between the two. By comparing example 1 with comparative example 5, it can be seen that the reinforcing component can improve the early swelling energy. In conclusion, the anti-cracking agent can compensate concrete shrinkage in a full period, and the early compensation shrinkage performance is improved while the later compensation shrinkage effect is not reduced.
(3) Testing of concrete Properties
The anti-cracking agents of examples 1 to 6 and comparative examples 1 to 7 of the invention are mixed into concrete according to the following mixing ratio: 285 parts of P.O 42.5 ordinary portland cement, 60 parts of S95-grade mineral powder, 85 parts of II-grade fly ash, 771 parts of river sand, 1015 parts of broken stone, 7.2 parts of polycarboxylic acid water reducing agent, 165 parts of water and 25.8 parts of hydration heat adjustment type magnesium high-efficiency anti-cracking agent;
the slump of the concrete mixture is detected according to GB/T50080-2016 standard of test method for the performance of common concrete mixtures; the compressive strength of the concrete is determined according to GB/T50081-2019 standard of mechanical property test method of common concrete; the shrinkage and crack reduction coefficients of the concrete are determined by referring to GB/T50082-2009 test method standards for long-term performance and durability of common concrete and T/CECS 10001-2019 anti-cracking and anti-permeability composite materials for concrete, and the test results are shown in Table 3.
TABLE 3 concrete Performance test results
As can be seen from the test results in Table 3, by comparing slump data, the anti-cracking agent disclosed by the invention has little influence on the slump of concrete, but can improve the retaining effect of the fluidity of the concrete, and the 1h slump loss is weakened compared with that of a blank group. The compressive strength data are compared to show that the anti-cracking agent can improve the compressive strength of concrete, and compared with the blank groups, the compressive strength ratio of 7d is more than or equal to 100%, the compressive strength ratio of 28d is more than or equal to 105%, and the compressive strength ratio of 60d is more than or equal to 105%, the anti-cracking agent has a promotion effect on the long-term mechanical property of the concrete. By comparing the shrinkage rate and the crack reduction coefficient, the crack resistance agent can reduce the drying shrinkage of concrete, and compared with a blank group, the shrinkage rate can be reduced by more than 50%; and the early plastic shrinkage performance of the concrete can be effectively weakened, so that the crack reduction coefficient of the concrete can exceed 50 percent.
It can be seen by comparing example 1 with comparative example 5 that comparative example 5 lacks the reinforcing component, the compressive strength of the concrete at each age is remarkably reduced, and the crack reduction coefficient is also remarkably reduced. By comparing example 1 with comparative example 6, it can be found that when 3-aminopropanol is absent in the shrinkage reducing component, the shrinkage rate of the concrete is remarkably increased, and the crack reduction coefficient is reduced, which shows that the self-shrinkage of the concrete can be effectively reduced by compounding the ethylene glycol, the polyoxypropylene glycol and the 3-aminopropanol.
FIG. 1 is a graph showing the free deformation of the blank concrete test pieces incorporating the crack inhibitors of example 1 and comparative examples 1 to 2, the negative value indicating volume shrinkage and the positive value indicating volume expansion. As can be seen from FIG. 1, the hydration heat adjustable magnesium high-efficiency anticracking agent of the present invention has an excellent shrinkage compensation effect on concrete.
According to the test results, the hydration heat regulating type magnesium efficient anti-cracking agent has the effect of improving the workability and long-term mechanical property of concrete, can obviously reduce the hydration heat of cement, reduce the cracking risk of the concrete caused by temperature shrinkage, can play a role in full-period compensation shrinkage, has an obvious early compensation shrinkage effect and no weakening later effect, can reduce the drying shrinkage and self-shrinkage effects of the concrete, and can improve the anti-cracking property and long-term durability of the concrete from the aspects.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. The hydration heat regulation type magnesium high-efficiency anti-cracking agent is characterized by comprising the following components in percentage by mass: 50 to 80 percent of expansion component, 1 to 5 percent of hydration heat regulating component, 1 to 5 percent of shrinkage reducing component and 10 to 45 percent of reinforcing component;
the preparation method of the expansion component comprises the following steps:
s1, uniformly mixing magnesium oxide and ammonium chloride according to a mass ratio of 10;
s2, calcining the particles obtained in the step S1 at 350-550 ℃, cooling, and grinding to obtain powder;
s3, mixing the powder obtained in the step S2 with the activated carbon powder according to the mass ratio of 100; the mass fraction of the acid solution is 20%, and the acid solution comprises at least one of acetic acid, malic acid, citric acid, tartaric acid or tannic acid;
the preparation method of the hydration heat regulating component comprises the following steps: heating starch to 130 to 200 ℃, preserving heat for 1 to 2h, and cooling to room temperature; then dispersing the heated starch in a gluconic acid solution according to the mass ratio of 1;
the shrinkage reducing component comprises the following components in percentage by mass: 15 to 40 percent of ethylene glycol, 40 to 60 percent of polypropylene oxide glycol and 10 to 25 percent of 3-aminopropanol;
the reinforcing component comprises the following components in percentage by mass: 5 to 20 percent of sodium bicarbonate, 55 to 80 percent of superfine mineral powder, 5 to 30 percent of anhydrite and 0.002 to 0.02 percent of hydroxypropyl methyl cellulose ether.
2. The hydration heat-regulated magnesium based highly potent anti-cracking agent according to claim 1, wherein the starch comprises at least one of sweet potato starch, water chestnut starch, corn starch, lotus root starch or pea starch.
3. The hydration heat regulation type magnesium high-efficiency anti-cracking agent according to claim 1, wherein the specific washing method comprises repeatedly washing and filtering the precipitate obtained after separation until the pH of the solution is between 5.0 and 7.0.
4. The hydration heat regulation type magnesium high-efficiency anti-cracking agent as claimed in claim 1, wherein the specific surface area of the hydration heat regulation component obtained after grinding is 200 to 300m 2 /kg。
5. The hydration heat adjustable magnesium high-efficiency anti-cracking agent according to claim 1, wherein the specific surface area of the superfine mineral powder is 800 to 1000m 2 Per kg SO in anhydrite 3 The content of the hydroxypropyl methyl cellulose is more than or equal to 45 weight percent, and the viscosity of the hydroxypropyl methyl cellulose is 10 ten thousand.
6. The preparation method of the hydration heat regulating type magnesium high-efficiency crack resistance agent as claimed in any one of claims 1 to 5, which is characterized by comprising the following steps: mixing the expansion component, the hydration heat regulating component and the reinforcing component according to a proportion, and adding the shrinkage reducing component in a spraying mode in the mixing and stirring process to obtain the hydration heat regulating type magnesium high-efficiency anti-cracking agent.
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| JPS5048028A (en) * | 1973-08-27 | 1975-04-28 | ||
| US20140060391A1 (en) * | 2012-08-28 | 2014-03-06 | Pkl Corporation | Shrinkage-compensating concrete |
| CN109293266B (en) * | 2018-10-24 | 2021-11-12 | 贵州鼎盛建材实业有限公司 | Hydration heat inhibition type expansion fiber composite anti-cracking agent and preparation method thereof |
| CN110734245A (en) * | 2019-10-29 | 2020-01-31 | 武汉三源特种建材有限责任公司 | Hydration heat inhibition type concrete anti-cracking waterproof agent, preparation method and application thereof |
| CN113173725B (en) * | 2021-05-26 | 2023-02-07 | 广东粤盛特种建材有限公司 | Efficient concrete expansion anti-cracking waterproof agent and preparation method thereof |
| CN113213807B (en) * | 2021-05-29 | 2022-08-30 | 石家庄市长安育才建材有限公司 | Composite anti-cracking agent for ultra-long large-volume concrete and preparation method thereof |
| CN113603385B (en) * | 2021-08-09 | 2022-08-12 | 武汉三源特种建材有限责任公司 | Hydration heat inhibition type concrete anti-cracking waterproof agent and preparation method thereof |
| CN113603388B (en) * | 2021-08-23 | 2022-09-16 | 广西御龙新型材料有限公司 | Concrete reinforced compact and temperature-adjustable anti-cracking agent and preparation method thereof |
| CN114477829B (en) * | 2022-01-17 | 2022-09-09 | 西安建祥建材科技有限公司 | Multi-component composite reinforced anti-cracking agent for concrete and preparation method thereof |
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