CN113929341A - Nano crystal seed ultra-early strength agent suitable for low-temperature environment and preparation method thereof - Google Patents
Nano crystal seed ultra-early strength agent suitable for low-temperature environment and preparation method thereof Download PDFInfo
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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
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/10—Accelerators; Activators
- C04B2103/14—Hardening accelerators
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- 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
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- Y02W30/91—Use of waste materials as fillers for mortars or concrete
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Abstract
The invention discloses a nano crystal seed ultra-early strength agent suitable for a low-temperature environment and a preparation method thereof, wherein the nano crystal seed ultra-early strength agent is prepared from the following components in percentage by mass; 10-20% of calcium source, 5-10% of silicon source, 0.5-1.5% of high-stability suspension dispersant, 5-10% of auxiliary early strength agent and 0.05-0.1% of pH value regulator, and the balance of water and inevitable impurities; wherein the auxiliary early strength agent is added after the C-S-H precursor is formed, and finally the nano seed crystal super early strength agent is formed. The nano crystal seed super early strength agent has the characteristics of strong operability and suitability for batch production, has small influence on the working performance of concrete in a low-temperature environment, obviously improves the early strength, has no reverse shrinkage of the later strength, has high application value in the aspect of improving the winter production efficiency of prefabricated parts, and overcomes the performance defect of the existing early strength agent and the problem of poor early strength effect at low temperature.
Description
Technical Field
The invention relates to the technical field of concrete admixtures, in particular to a nano-crystal seed ultra-early strength agent suitable for a low-temperature environment and a preparation method thereof.
Background
At present, the application of early strength concrete in the commercial concrete industry is more concentrated in prefabricated parts, and with the advance of national infrastructure, the requirement of building prefabrication rate is increased year by year, and the application of the early strength concrete in the prefabricated parts is wider and wider. In order to improve the production efficiency, a prefabricated part factory generally uses early strength concrete or carries out steam curing after pouring to improve the early strength of a part, so that the early strength of the part can meet the standard demolding strength requirement as soon as possible, and the production profit is increased by accelerating the turnover rate of a mold. The steam curing early-stage equipment has large capital investment, high energy consumption and certain pollution to the environment. Meanwhile, the concrete test block can make the hydrated crystal of the cement have large size under the high-temperature steam curing, the durability is reduced, the risk of strength reduction exists, the probability of surface cracks and through cracks of the member is high, the overall quality of the prefabricated member is influenced, extra repair and maintenance are carried out, and the production cost is increased. Therefore, in order to ensure the quality of the prefabricated parts and improve the production efficiency, the early strength agent is a new selection direction.
The common traditional early strength admixture is easy to cause negative influence on the physical performance of concrete due to the mixing amount problem, for example, the dosage of the triethanolamine early strength admixture is not easy to control, and overdoping is easy to cause ultra-retarding; the chlorine-containing early strength agent is easy to cause the corrosion of the steel bar; the sulfate type early strength agent is easy to cause the reduction of the impermeability and the corrosion resistance of the concrete, and the like, thereby causing the deterioration of the durability of the concrete, and the like. Although the compound early strength agent can avoid the problems to a certain extent, the compound debugging process is complicated and the adaptability is poor. In addition, the traditional early strength agent has low early strength efficiency under normal mixing amount due to the reason of an early strength mechanism and the like under a low-temperature environment. Therefore, the traditional early strength component can not meet the requirements of green and high-performance concrete gradually, and the mode of applying seed crystal nucleation is a new direction for improving the early strength of the concrete.
Chinese patent CN107337372A discloses an early strength agent based on composite nano material, which is prepared by preparing suspension from nano calcium carbonate and dispersant, and mixing with soluble calcium salt and soluble silicate. The high-molecular dispersing agent is introduced to ensure the good dispersion of the nano particles, and then two different nano materials with different activities, early strength effects and complementary aging are introduced to realize the advantage complementation between the early strength components, so that the nano material has a remarkable early strength effect under the condition of low doping amount.
Chinese patent CN108467215A discloses an early strength agent for nanometer C-S-H seed crystal, the technical scheme is approximately: adding an acrylic monomer, a silane coupling agent and modified polyoxyethylene ether into an oxidation-reduction system consisting of ammonium persulfate, vitamin C and dodecyl mercaptan, preparing a high molecular polymer with the molecular weight of 4000-20000 through a polymerization reaction, taking the high molecular polymer as a base solution, and adding sodium metasilicate and calcium nitrate to prepare the nano C-S-H seed crystal early strength agent. Calcium nitrate and sodium metasilicate are mixed to generate calcium metasilicate precipitate, a silane coupling agent part in a high molecular polymer forms bonding with an inorganic interface of the precipitate, the silane coupling agent is adsorbed on the surface of the precipitate particles, the precipitate particles are dispersed, the contact between the particles is prevented, and the aim of limiting the precipitate particles to grow continuously is fulfilled. The nucleating agent can be used as a nucleating point of a cement hydration product to greatly reduce a potential barrier, accelerate the cement hydration reaction process and obviously improve the early strength.
Chinese patent CN111847977A discloses a nanometer PCE-CSH crystal nucleus early strength agent and a preparation method thereof, and the technical scheme is approximately as follows: and (3) taking the aqueous solution of the polycarboxylic acid dispersant C as a base material, and simultaneously dropwise adding the soluble calcium source aqueous solution and the soluble silicon source aqueous solution into the base material to obtain the nano PCE/CSH crystal nucleus early strength agent. According to the patent technology, alkoxysilane capable of generating chemical bonding with C-S-H crystal nucleus is introduced into a dispersing agent structure, so that chemical bonding dispersion is realized to replace charge adsorption dispersion, a dispersion system is stable, the dispersion degree of the C-S-H crystal nucleus is improved, and the growth of the C-S-H crystal nucleus is inhibited.
However, the dispersant used in the above patent technology is usually a polycarboxylic acid type water reducing agent with high content, on one hand, the use cost is high, and the workability of concrete is greatly affected and is difficult to control after the polycarboxylic acid water reducing agent is high content, because the early strength agent product is mainly used for producing prefabricated parts, and the thinner structures such as laminated plates in the prefabricated parts need less slump to ensure the overall strength during production; in addition, the product of the invention has low early strength amplification at normal temperature, the compression strength amplification at 12h is only about 100-200%, the early strength amplification is smaller when the environment is at low temperature, and the strength requirement of normal demoulding of the prefabricated part can not be met within 16h without steam curing.
Disclosure of Invention
The invention aims to: aiming at the problems of performance defects of the existing early strength agent and poor early strength effect at low temperature, the invention provides the nano crystal seed ultra-early strength agent suitable for the low temperature environment and the preparation method thereof.
The technical scheme adopted by the invention is as follows: the nanometer crystal seed super early strength agent is suitable for a low-temperature environment and is prepared from the following components in percentage by mass; 10-20% of calcium source, 5-10% of silicon source, 0.5-1.5% of high-stability suspension dispersant, 5-10% of auxiliary early strength agent and 0.05-0.1% of pH value regulator, and the balance of water and inevitable impurities; wherein the auxiliary early strength agent is added after the C-S-H precursor is formed, and then the nano crystal seed super early strength agent is formed.
In the formula of the nano crystal seed ultra-early strength agent, the main innovation point is the use of a high-stability suspension dispersant and an auxiliary early strength agent, and the high-stability suspension dispersant can act on the C-S-H crystal seed through Van der Waals force and pi-pi conjugation so as to obtain excellent dispersion stability; the auxiliary early strength agent is mainly used for breaking C3S (tricalcium silicate, 3 CaO. SiO2) Metastable overlayer of surface, thereby introducing C3S is released from the aggregate, thereby playing a synergistic role in accelerating early hydration of the cement.
Furthermore, for the nano-scale early strength agent prepared by adopting a liquid phase method, for example, the nano-scale nano crystal seed ultra-early strength agent disclosed by the invention mainly comprises nano C-S-H, so that crystal seeds can be provided for the formation of a main hydration product C-S-H gel of cement, namely, a micro-center substance is provided for the hydration of the cement, the potential barrier generated by the C-S-H gel is reduced, and the C-S-H gel is greatly shortened3The time for converting S into C-S-H enables a large amount of C-S-H gel to be generated in the early stage of hydration, thereby greatly improving the early stage hydration process of cement. However, as the size of the nanoparticle decreases, the specific surface energy thereof rapidly increases, which is extremely unstable in thermodynamics, and the nanoparticle has an extremely large specific surface and a high specific surface energy, and is highly likely to cause particle agglomeration and aggregation to form secondary particles during preparation and post-treatment processes, thereby increasing the particle size due to aggregation and ostwal ripening mechanism, etcFor this reason, the function of the ultrafine particles is lost in the final use. Therefore, the problem of particle agglomeration of the nano C-S-H early strength agent is always the key point of experimental research. In patent CN111847977A, it is to use polycarboxylic acid dispersant C to increase the dispersion degree of nano C-S-H crystal nucleus, and further to solve the problem of particle agglomeration. However, when the cement hydration is carried out for a certain period of time, the hydration products that have been formed are caused to agglomerate at C due to the van der Waals forces3S indicates the formation of a metastable overlayer resulting in C3The hydration efficiency of S becomes very low, which has not been solved by increasing the dispersion degree of nano C-S-H crystal nuclei. In order to overcome the problem, in the invention, the auxiliary early strength agent is added into the nano C-S-H seed crystal early strength agent, and the addition of the auxiliary early strength agent can break the adsorption of the auxiliary early strength agent on C3Metastable coating of S surface to release C that has not yet been hydrated3And the S is matched with the C-S-H crystal seed prepared by using the high-dispersity suspension dispersant for use, so that the early hydration of cement is accelerated together, the early strength effect of the super early strength agent is improved, and the super early strength agent is particularly suitable for steam-curing-free production of prefabricated parts in a low-temperature environment.
In the present invention, the high stability suspension dispersant is polyvinylpyrrolidone (PVP) having a molecular weight of 10000-100000. PVP is taken as a surface active material with excellent performance, which can be adsorbed on the surface of nanoparticles through Van der Waals force to prevent agglomeration among nanoparticles on one hand, and the main action mechanism is as follows: when PVP is adsorbed on the surface of the particles, microcell states are formed on the PVP, due to the existence of the active agent, the generated repulsive force between the particles prevents the nano-scale C-S-H from being in direct contact, and therefore agglomeration is prevented. The PVP molecule contains two types of functional groups with different properties, one type is a polar group with hydrophilicity, the other type is a non-polar functional group with lipophilicity, the inorganic nano particles are dispersed in aqueous solution, the non-polar lipophilic group of the surfactant is adsorbed on the surface of the particles, and the polar hydrophilic group is dissolved with water, so that the aim of good dispersibility of the inorganic nano particles in water is fulfilled; on the contrary, the nanoparticles are dispersed in a nonpolar oily solution, the polar functional group of the surfactant is adsorbed to the surface of the nanoparticles, and the nonpolar functional group is dissolved in an oily medium. On the other hand, PVP is used as a linear polymer with a pyrrolidone five-membered ring structure, the five-membered ring structure and pi electrons on the C-S-H nano particles form pi-pi conjugation, after the PVP is adsorbed on the surface of the C-S-H seed crystal, the long chain of the PVP can be adsorbed on the surface of the C-S-H seed crystal to play a role in steric hindrance through the pi-pi conjugation, so that the dispersion stability of the PVP on the C-S-H seed crystal is shown, the dispersion degree of the C-S-H seed crystal is improved through the dispersion effect of the PVP in two aspects, and the technical effect of high-stability suspension dispersion is achieved. Furthermore, tests show that when the molecular weight of PVP is smaller, the adsorption capacity of pi-pi conjugation is weak due to the relatively shorter molecular chain size and the less cyclic structure of pyrrolidone, the dispersion effect is limited, and the technical effect cannot be expected; on the contrary, when the molecular weight of PVP is too large, a plurality of C-S-H particles can be adsorbed on the same molecular chain due to the overlong molecular chain size, so that the adsorption capacity of the PVP on C-S-H is weakened to influence the adsorption capacity, and finally, the displayed dispersity is not satisfactory. Therefore, when PVP with a proper molecular chain size acts on the C-S-H crystal seed through Van der Waals force and pi-pi conjugation, the PVP can show better adsorption capacity and higher adsorption capacity on the C-S-H crystal seed, so that a good steric hindrance modification effect is achieved, and excellent dispersion stability is achieved. It is concluded from experiments that the molecular weight of PVP is 10000-100000, and the claimed technical effect is difficult to achieve if the molecular weight is beyond this range.
In the invention, the auxiliary early strength agent is one or more of sodium metaaluminate, aluminum sulfate, triethanolamine, triisopropanolamine, urea and calcium formate, and is specifically selected and determined according to actual needs.
Further, the calcium source is one or more of calcium chloride, calcium bromide, calcium nitrate tetrahydrate, calcium nitrate nonahydrate, calcium formate and calcium lactate.
Further, the silicon source is one or a combination of more of sodium metasilicate, sodium silicate pentahydrate and magnesium silicate.
The invention also comprises a preparation method of the nano seed crystal super early strength agent suitable for the low-temperature environment, which comprises the following steps:
s1, weighing water and a high-stability suspension dispersant in a designed amount, and fully mixing to obtain a solution A;
s2, respectively weighing a soluble calcium source solution and a soluble silicon source solution in designed amounts according to the calcium-silicon molar ratio of 1.0-3.0, and then adding the soluble calcium source solution and the soluble silicon source solution into the solution A in a dropwise manner;
and S3, after the dropwise addition is finished, adjusting the pH value of the solution to 11-13 by using a pH value regulator (preferably nitric acid or sodium hydroxide), adding the designed amount of auxiliary early strength agent after the C-S-H precursor is generated, and uniformly stirring to obtain the C-S-H precursor.
Further, in S2, the solution A was magnetically stirred at a stirring speed of 400-1000r/min during the dropping.
Further, in S2, the soluble calcium source solution and the soluble silicon source solution were added dropwise at a rate of 0.5 to 1.5ml/min and a rate of 0.3 to 0.9ml/min, respectively.
Further, the nano-seed crystal ultra early strength agent suspension solution with the solid content of 10-20% is obtained in the step S3, and the micro particle size of the nano-seed crystal ultra early strength agent is 30-80 nm.
The invention also comprises the application of the nano crystal seed super early strength agent suitable for the low-temperature environment, wherein the nano crystal seed super early strength agent is prepared by the preparation method, the early strength agent is used as an additive of concrete, and the dosage of the early strength agent is 1-6% of the dosage of a concrete cementing material.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
1. the high-stability suspension dispersant and the auxiliary early strength agent are introduced into the nano crystal seed super early strength agent, the high-stability suspension dispersant can act on the C-S-H crystal seed through Van der Waals force and pi-pi conjugation, so that excellent dispersion stability is obtained, and the auxiliary early strength agent is used for breaking the C-S-H crystal seed3Metastable overlayer of S surface, thereby adding C3S is released from the agglomeration, thereby playing a synergistic effect of accelerating early hydration of cement and improving the early strength effect of the early strength agent;
2. the invention provides a nano crystal seed super early strength agent different from the existing nano crystal seed super early strength agent aiming at the problems of performance defect of the existing early strength agent and poor early strength effect at low temperature, the nano crystal seed super early strength agent has the characteristics of strong operability and suitability for batch production, the product has small influence on the working performance of concrete in a low-temperature environment, the early strength is obviously improved, the later strength is not shrunk, the application value in the aspects of reducing the steam curing cost of prefabricated parts and improving the production efficiency is very high, and the problems of performance defect of the existing early strength agent and poor early strength effect at low temperature are overcome.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear and thorough, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
A nanometer crystal seed ultra-early strength agent suitable for low-temperature environment is prepared by the following steps:
s1, weighing 50g of PVP with the molecular weight of 30000 and 600g of distilled water in a flat-bottomed flask, and then placing the flat-bottomed flask in a magnetic stirrer at 20 ℃ and 500r/min for fully mixing to be used as a base solution for later use;
s2, respectively weighing 75g of 1mol/L sodium metasilicate solution and 100g of 1mol/L calcium nitrate tetrahydrate solution for later use, and then simultaneously adding the solutions into the base solution of S1 at the dropping rates of 0.3ml/min and 0.5ml/min by using a peristaltic pump; after the dropwise addition is finished, adding a proper amount of 3mol/L sodium hydroxide into the flask to adjust the pH to 12.0;
s3, adding 50g of aluminum sulfate and urea into the flask after stirring for 1h, wherein the mass ratio of the aluminum sulfate to the urea is 1: 1, then supplementing the whole mass of the solution to 1000g, and continuing stirring for 1h to obtain the nano seed crystal super early strength agent solution with the solid content of 11.9%.
The optimum dosage of the nano-crystal seed ultra early strength agent is recommended to be 3%.
Example 2
A nanometer crystal seed ultra-early strength agent suitable for low-temperature environment is prepared by the following steps:
s1, weighing 100g of PVP with the molecular weight of 50000 and 500g of distilled water in a flat-bottomed flask, and then placing the flat-bottomed flask in a magnetic stirrer at 40 ℃ and 600r/min for fully mixing to be used as a base solution for later use;
s2, weighing 100g of 1mol/L sodium metasilicate solution and 100g of 1mol/L calcium nitrate tetrahydrate solution for later use, then simultaneously adding the base solution at the dropping rates of 0.4ml/min and 0.6ml/min by using a peristaltic pump, and after the dropping is finished, adding a proper amount of 3mol/L sodium hydroxide into the flask to adjust the pH to 11.7;
s3, adding 60g of calcium formate and triisopropanolamine into the flask after stirring for 1.5h, wherein the mass ratio of the calcium formate to the triisopropanolamine is 75: 2; then the whole mass of the solution is supplemented to 1000g, and then the solution is continuously stirred for 2h, so as to obtain the nano seed crystal super early strength agent solution with the solid content of 13.1%.
The optimum mixing amount of the nano-crystal seed ultra early strength agent is recommended to be 2%.
Example 3
A nanometer crystal seed ultra-early strength agent suitable for low-temperature environment is prepared by the following steps:
s1, weighing 120g of PVP with the molecular weight of 90000 and 500g of distilled water in a flat-bottomed flask, and then placing the flat-bottomed flask in a magnetic stirrer at the temperature of 60 ℃ and at the speed of 600r/min for fully mixing to be used as a base solution for later use;
s2, respectively weighing 50g of 1mol/L sodium metasilicate solution and 150g of 1mol/L calcium nitrate tetrahydrate solution for later use, then simultaneously adding the base solution at the dropping rates of 0.9ml/min and 1.5ml/min by using a peristaltic pump, and after the dropping is finished, adding a proper amount of 3mol/L sodium hydroxide into the flask to adjust the pH to 13.0;
s3, adding 100g of sodium metaaluminate and calcium formate into the flask after stirring for 2 hours, wherein the mass ratio of sodium metaaluminate to calcium formate is 1: 1.5, then supplementing the whole mass of the solution to 1000g, and continuing stirring for 3h to obtain the nano-crystal seed ultra-early strength agent solution with the solid content of 14.8 percent.
The optimum dosage of the nano-crystal seed ultra early strength agent is recommended to be 3%.
Comparison of test data results
In order to further verify the physical properties of the self-made nano crystal seed ultra-early strength agent in a low-temperature environment and guide the actual production for use, the concrete test is carried out on the crystal seed ultra-early strength agent samples prepared under different conditions and certain commercially available nano crystal seed ultra-early strength agent samples. The concrete physical property related test method refers to GB/T50080-2016 and GB/T50081-2002, wherein the test environment temperature is 7 ℃, test blocks are maintained at the test temperature for 16H and 1d, a control group 1 uses a certain commercially available nano-crystal seed super-early strength agent, the doping amount is 5%, the solid content is 10%, an additive used by a control group 2 is a part only containing the C-S-H crystal seed early strength agent in the example 1, the two control groups are used for verifying the excellent dispersion effect of the high-stability suspension dispersant and the synergistic effect of the auxiliary early strength agent, and the examples are the prepared additive products. The test mixing ratio is shown in table 1, and the concrete related performance test is shown in table 2.
TABLE 1 concrete mix proportion (unit kg/m)3)
| Item | Water (W) | Cement | Fly ash | Machine-made sand | Fine stone | Large crushed stone | Water reducing agent | Early strength agent |
| Reference group | 176 | 390 | 20 | 766 | 106 | 951 | 6.15 | 0 |
| Control group 1 | 158 | 390 | 20 | 766 | 106 | 951 | 6.15 | 20.5 |
| Example 1 | 165 | 390 | 20 | 766 | 106 | 951 | 6.15 | 12.3 |
| Control group 2 | 170 | 390 | 20 | 766 | 106 | 951 | 6.15 | 12.3 |
| Example 2 | 168 | 390 | 20 | 766 | 106 | 951 | 6.15 | 8.2 |
| Example 3 | 169 | 390 | 20 | 766 | 106 | 951 | 6.15 | 8.2 |
TABLE 2 Effect of seed early Strength Agents on concrete Performance
From tables 1 and 2, the following conclusions can be drawn:
(1) in a low-temperature environment, the slump loss and the expansion loss of the reference group and the control group 1 are large after 1h, while the workability of the concrete is not changed greatly and the slump loss and the expansion change are small after 1h in the example group. Therefore, the initial workability of the commercial seed crystal early strength agent on concrete in a low-temperature environment is less influenced, but the loss is larger with time; the seed crystal early strength agent has small time loss on the workability of the concrete, namely, the seed crystal early strength agent has an effect of improving the workability of the concrete;
(2) under a low-temperature environment, the concrete can be obtained by comparing the compressive strength performance, the early strength agent of the crystal seeds is introduced to obviously improve the early mechanical properties (compressive strength of 16h and 1 d) of the concrete, and the later strength of the concrete is not inverted; the contrast group 1 is compared with the embodiment group, after the seed crystal early strength agent is used, the 16h compressive strength is increased by more than 300% (the 16h compressive strength of the reference group is taken as a base number), the 16h compressive strength of the contrast group is increased by 76%, the technical effect is far inferior to that of the seed crystal early strength agent, the seed crystal early strength agent is obviously higher than that of a commercially available product in the aspects of workability and early strength increase, and the nano seed crystal early strength agent is an early strength agent product which is good in suspension stability and excellent in early strength performance in a low-temperature environment, so that the problems of performance defects of the existing early strength agent and poor early strength effect at low temperature are overcome;
(3) in order to verify the excellent dispersing effect of the high-stability suspension dispersant used in the present invention and the synergistic effect of the auxiliary early strength agent, a control group 1 and a control group 2 were provided on the basis of example 1; the test results of the comparison of the control group 1 and the control group 2 show that although the self-made seed crystal early strength agent of the control group 2 does not contain the auxiliary early strength component, the workability and the early strength increase of the self-made seed crystal early strength agent are higher than those of the commercial products, and the use effect of the high-stability suspension dispersant is better than that of the existing dispersant; compared with the comparison result of 2 and 1, the C-S-H seed crystal early strength agent is obviously inferior to the example 1 in the aspects of the workability and the early strength increase after the auxiliary early strength agent is lacked, so that the introduction of the auxiliary early strength agent further improves the early strength effect of the seed crystal early strength agent, and a synergistic effect is generated between the two.
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 and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The nano crystal seed ultra early strength agent suitable for the low-temperature environment is characterized by being prepared from the following components in percentage by mass; 10-20% of calcium source, 5-10% of silicon source, 0.5-1.5% of high-stability suspension dispersant, 5-10% of auxiliary early strength agent and 0.05-0.1% of pH value regulator, and the balance of water and inevitable impurities; wherein the auxiliary early strength agent is added after the C-S-H precursor is formed, and then the nano crystal seed super early strength agent is formed.
2. The nano-seed crystal super early strength agent suitable for low temperature environment as claimed in claim 1, wherein the high stability suspension dispersant is polyvinylpyrrolidone with molecular weight of 10000-100000.
3. The nano-seed crystal super early strength agent suitable for use in low temperature environment of claim 1, wherein the auxiliary early strength agent is one or more of sodium metaaluminate, aluminum sulfate, triethanolamine, triisopropanolamine, urea, and calcium formate.
4. The nano-seed crystal ultra early strength agent suitable for use in low temperature environment of claim 1, wherein the calcium source is one or more of calcium chloride, calcium bromide, calcium nitrate tetrahydrate, calcium nitrate nonahydrate, calcium formate and calcium lactate.
5. The nano-seed ultra early strength agent suitable for use in low temperature environments of claim 1, wherein the silicon source is one or more of sodium metasilicate, sodium pentahydrate, and magnesium silicate.
6. The method for preparing a nano-seed ultra early strength agent suitable for use in a low temperature environment according to any one of claims 1 to 5, comprising the steps of:
s1, weighing water and a high-stability suspension dispersant in a designed amount, and fully mixing to obtain a solution A;
s2, respectively weighing a soluble calcium source solution and a soluble silicon source solution in designed amounts according to the calcium-silicon molar ratio of 1.0-3.0, and then adding the soluble calcium source solution and the soluble silicon source solution into the solution A in a dropwise manner;
and S3, after the dropwise addition is finished, adjusting the pH value of the solution to 11-13 by using a pH value regulator, adding the designed amount of auxiliary early strength agent after the C-S-H precursor is generated, and uniformly stirring to obtain the product.
7. The method for preparing the nano-seed crystal ultra-early strength agent suitable for the low temperature environment as claimed in claim 6, wherein in S2, the solution A is magnetically stirred during the dropping process, and the stirring speed is controlled at 400-1000 r/min.
8. The method of claim 6, wherein the soluble calcium source solution and the soluble silicon source solution are added dropwise at a rate of 0.5-1.5ml/min and a rate of 0.3-0.9ml/min, respectively, in S2.
9. The method of claim 6, wherein the nano-seed ultra early strength agent suspension solution with a solid content of 10-20% is obtained in step S3, and the micro particle size of the nano-seed ultra early strength agent is 30-80 nm.
10. The application of the nano-crystal seed ultra-early strength agent suitable for the low-temperature environment is characterized in that the nano-crystal seed ultra-early strength agent is prepared by the preparation method of claim 6, and the nano-crystal seed ultra-early strength agent is used as an additive of concrete, and the dosage of the nano-crystal seed ultra-early strength agent is 1-6% of the dosage of a concrete cementing material.
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| CN114920490A (en) * | 2022-05-28 | 2022-08-19 | 天津如米基业新材料有限公司 | Preparation method and application of super-strong particle crystal glue for concrete |
| CN115368052A (en) * | 2022-09-30 | 2022-11-22 | 安徽海螺材料科技股份有限公司 | Nano crystal nucleus type early strength cement grinding aid and preparation method thereof |
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