CN114873949B - Slow-release air entraining agent, preparation method thereof and concrete state retaining agent - Google Patents
Slow-release air entraining agent, preparation method thereof and concrete state retaining agent Download PDFInfo
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- CN114873949B CN114873949B CN202210796850.1A CN202210796850A CN114873949B CN 114873949 B CN114873949 B CN 114873949B CN 202210796850 A CN202210796850 A CN 202210796850A CN 114873949 B CN114873949 B CN 114873949B
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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
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
- C04B2103/304—Air-entrainers
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Abstract
The invention provides a slow-release air entraining agent, a preparation method thereof and a concrete state retaining agent, wherein the effective components of the slow-release air entraining agent comprise: the air entraining agent comprises an air entraining component and a slow release outer film for coating the air entraining component, wherein the slow release outer film is high polyester which can be hydrolyzed and broken under alkaline conditions. The slow-release air entraining agent is added into the cement concrete which presents alkalinity, and because the slow-release outer membrane is made of high polyester, the slow-release outer membrane is gradually hydrolyzed under the alkalinity condition, so that the air entraining components are slowly released, and the slow-release air entraining agent has the function of prolonging the air entraining time.
Description
Technical Field
The invention relates to the field of building materials, in particular to a slow-release air entraining agent and a preparation method thereof, and also relates to a concrete state retaining agent comprising the slow-release air entraining agent.
Background
The freeze-thaw damage and the salt freeze damage of concrete buildings, various structures, roads and marine engineering are always the focus of much attention. The introduction of fine, uniform and closed air bubbles into the concrete is beneficial to improving the durability of the concrete, and particularly the freeze-thaw resistance and the medium permeation resistance are improved most obviously. Meanwhile, the bubbles play roles of balls and floating supports in the mixing process, the mixing performance of the fresh concrete is improved, and the problems of segregation, bleeding and the like of the fresh concrete can be reduced.
However, as the mixing stations for producing concrete are far away from the construction site, the concrete mixing plant transports the concrete to the construction site for construction after mixing, the transport time consumption is different, some construction sites are very close to the mixing plant, one hour is not enough from the time when the concrete is taken out of the mixing plant to the time when construction is completed on the construction site, the transport process of some construction sites is two to three hours, and in addition, the on-site waiting time before pumping is added, so that the four to five hours are even needed when the concrete is discharged from the mixing plant to be pumped on the site. Therefore, the loss of the concrete air entraining agent is overlarge, and the air entraining agent is covered due to partial concrete hydration in the transportation process, so that the air entraining effect is poor.
Patent CN113121147A proposes a concrete air entraining agent with long-acting air entraining function, which adopts ester A of long-chain alkyl mercaptan to hydrolyze gradually under alkaline condition, the generated mercaptan (R-SH) can generate rapid addition with the double bond of maleimide in quaternary ammonium compound B with maleimide group, so as to generate reactant C with surfactant structure, and the gas content is increased gradually with the gradual increase of the content of reactant C with surfactant structure, thereby achieving the purpose of long-acting air entraining. However, it can be seen from the examples that although the reactant C having a surfactant structure has a certain air-entraining effect, the air-entraining time is still less than four to five hours.
Disclosure of Invention
In view of the above, the invention provides a slow-release air entraining agent which can continuously and slowly release air entraining components after concrete is conveyed away from a mixing station, so that the air entraining time is prolonged.
The slow-release air entraining agent comprises the following effective components: the air entraining agent comprises an air entraining component and a slow release outer membrane for coating the air entraining component, wherein the slow release outer membrane is high polyester which can be hydrolyzed and broken under alkaline conditions; the air entraining component is a rosin air entraining agent, and the slow release outer membrane is a copolymer of an acrylic monomer and polyhydric alcohol acrylate.
The slow-release air entraining agent is added into the cement concrete which presents alkalinity, the high polyester of the slow-release outer membrane of the slow-release air entraining agent is gradually hydrolyzed under the alkalinity condition, so that the air entraining component is slowly released, and the effect of prolonging the air entraining time is achieved.
Further, the preparation raw materials of the slow-release air entraining agent comprise, by weight: 20-30 parts of rosin air entraining agent, 10-20 parts of acrylic monomer, 0.3-0.8 part of polyol acrylate, 1-5 parts of emulsifier, 0.5-1 part of initiator and 40-60 parts of water.
Further, the rosin air entraining agent comprises sodium abietate and/or potassium abietate.
Further, the acrylic monomer comprises at least one of acrylic anhydride, methacrylic anhydride, methyl methacrylate and ethyl methacrylate.
Further, the polyol acrylate comprises at least one of 1, 4-butanediol dimethacrylate, 1, 3-butanediol dimethacrylate, ethylene glycol dimethacrylate and 1, 3-propylene glycol dimethacrylate.
Further, the emulsifier comprises sorbitan fatty acid ester and polyoxyethylene sorbitan fatty acid ester.
Further, the initiator includes at least one of cerium ammonium nitrate and cerium ammonium sulfate.
The invention also provides a preparation method of the slow-release air entraining agent, which comprises the following steps: adding an air entraining component and an initiator into water, stirring and dissolving to prepare aqueous phase liquid A; mixing acrylic monomers and polyol acrylate to prepare an oil phase liquid B; mixing the oil phase liquid B, the water phase liquid A and an emulsifier, and emulsifying under ultrasonic dispersion to obtain a water-oil emulsion; and stirring the water-oil emulsion, heating to 60-90 ℃, and fully reacting to obtain the slow-release air entraining agent.
The invention also provides a concrete state retaining agent, which comprises the following raw materials in parts by weight: 200-300 parts of water reducing agent, 100-200 parts of slump retaining agent, 5-10 parts of water retaining agent, 0.5-1 part of air entraining agent, 5-10 parts of slow release air entraining agent, 1-3 parts of slow release water retaining agent, 20-30 parts of retarder and 446-668.5 parts of water; the slow release water-retaining agent comprises the following raw materials in parts by weight: 10 to 20 portions of acrylamide monomer, 30 to 40 portions of slow release monomer, 0.3 to 0.5 portion of initiator and 3500 to 4000 portions of water.
The concrete state maintaining agent can keep the concrete in a basically consistent state with the machine-out state for a long time by adding the slow-release air entraining agent and matching with other additives, and meets the construction requirements of different time periods.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The experimental procedures in the following examples are all conventional ones unless otherwise specified. The test materials used in the following examples were purchased from a conventional biochemical reagent store unless otherwise specified. In addition, except for the specific description of the present embodiment, the terms and processes referred to in the present embodiment should be understood according to the common knowledge and conventional methods in the prior art.
The invention provides a slow-release air entraining agent, which comprises the following effective components: the air entraining agent comprises an air entraining component and a slow release outer film for coating the air entraining component, wherein the slow release outer film is high polyester which can be hydrolyzed and broken under alkaline conditions. The slow-release air entraining agent can be added when cement concrete is mixed, and because the cement concrete is alkaline, the high polyester of the slow-release outer membrane is gradually hydrolyzed under the alkaline condition, so that air entraining components are slowly released. After the concrete is stirred in the mixing station, the concrete is usually continuously stirred in the tank car in the process of being transported to a construction site by the tank car, and at the moment, the slow-release air entraining agent can still play a role in entraining air.
The air-entraining component can adopt the traditional air-entraining agents such as saponin air-entraining agents, alkyl sulfonate air-entraining agents and the like, and can also preferably adopt rosin air-entraining agents. The rosin air entraining agent is prepared by improving various functional materials such as natural nonionic tea saponin, anionic surface active resin and the like. The method has the characteristics of reducing the surface tension of the solution, generating closed independent bubbles, having high foaming times, large number of bubbles, small space between bubbles and long foam stabilizing time, obviously improving the working performance of plastic concrete and improving the durability of hardened concrete.
The slow release outer membrane is preferably a copolymer of acrylic monomers and polyol acrylate, and because the molecular weight of the acrylic monomers and the polyol acrylate is usually smaller, the network structure of high polyester generated after copolymerization is more compact, and the wrapping property of the air entraining component is better. Although the air-entraining effect of the rosin air-entraining agent is good, the rosin air-entraining agent cannot be compounded with the polycarboxylic acid water reducing agent, and the high-polyester slow-release outer membrane has good adaptability with the polycarboxylic acid water reducing agent, so the slow-release air-entraining agent is suitable for being compounded with the polycarboxylic acid water reducing agent. If the molecular size of the slow release outer membrane is too large, precipitates are easy to form, and the slow release type air entraining effect is influenced. More preferably, therefore, the outer sustained release membrane has a molecular size of < 50 microns.
The preparation of the slow-release air entraining agent can specifically adopt the following raw materials in parts by weight: 20-30 parts of rosin air entraining agent, 10-20 parts of acrylic monomer, 0.3-0.8 part of polyol acrylate, 1-5 parts of emulsifier, 0.5-1 part of initiator and 40-60 parts of water.
The rosin-based air entraining agent may be a conventional modified rosin thermopolymer, a rosin acid salt, or the like, and may preferably include sodium rosin acid and/or potassium rosin acid. The sodium abietate and the potassium abietate have similar structures and properties, are hydrophobic surfactants, have larger surface activity on a solution-air interface, and can obviously reduce the surface tension. When the liquid mixed with the sodium abietate or the potassium abietate is stirred, air is easily mixed into the liquid, and bubbles with higher concentration are generated; moreover, as the sodium abietate or the potassium abietate has better elastic effect, the surface rheological property of the solution is also better after the solution reaches a certain concentration; the film thickness is stable. These factors result in the production of bubbles having a higher stability. The sodium abietate or potassium abietate is used as an air entraining agent, and a large amount of discontinuous, tiny and closed bubbles are introduced under a proper mixing amount, so that the workability of the mortar can be improved to a certain extent, the pore distribution is improved when the mortar is frozen at an early stage, and frost heaving stress generated by freezing of unhydrated part of water is resisted.
The acrylic monomer of the present invention may be selected from conventional acrylic acid derivatives such as hydroxyethyl acrylate, t-butyl acrylate, n-butyl acrylate, etc., and may preferably be at least one of more polymerizable monomers including acrylic anhydride, methacrylic anhydride, methyl methacrylate, and ethyl methacrylate. The polyol acrylate may be commercially or homemade, and may be a conventional polyol acrylate, such as propylene glycol acrylate, ethylene glycol acrylate, pentaerythritol acrylate, etc., and it may be preferably a raw material having a methyl group on an acrylic group to facilitate polymerization, such as at least one selected from 1, 4-butylene glycol dimethacrylate, 1, 3-butylene glycol dimethacrylate, ethylene glycol dimethacrylate, and 1, 3-propylene glycol dimethacrylate. The initiator can be common peroxide, or at least one of ammonium cerium nitrate and ammonium cerium sulfate can be selected, so that the homopolymer generation is less when the acrylic monomer and the polyalcohol acrylate are polymerized, and the copolymer generation is more.
The emulsifier of the slow-release air entraining agent is a substance which can form stable emulsion by a mixed solution of two or more immiscible components. The principle of action is that during the emulsification process, the dispersed phase is dispersed in the form of droplets (micron-sized) in the continuous phase, and the emulsifier reduces the interfacial tension of the components in the mixed system and forms a firmer film on the surface of the droplets or forms an electric double layer on the surface of the droplets due to the electric charge given by the emulsifier, thus preventing the droplets from aggregating with each other and maintaining a uniform emulsion. Because the high polyester of the slow release outer membrane is in an oil phase and the air entraining agent is in a water phase, the high polyester and the air entraining agent are mixed and easily layered, and the high polyester and the air entraining agent can be well fused by adding the emulsifier. The emulsifier can be common raw materials with hydrophilic group and hydrophilic oil group, and preferably can be nonionic surfactant, such as sorbitan fatty acid ester (span) and polyoxyethylene sorbitan fatty acid ester (tween), wherein the mixture of span-20 and tween-80 is more preferably used.
The slow-release air entraining agent is mainly prepared by adopting an emulsion polymerization mode. I.e. a polymerization reaction initiated by an initiator, in which the monomers are dispersed in water as an emulsion by the action of an emulsifier and with the aid of mechanical stirring. The monomers are acrylic monomers and polyol acrylate monomers as described in this patent. Water is used as a dispersant, and the rosin air entraining agent can be dissolved in water, so the dispersion system is an aqueous solution containing the air entraining agent. In the polymerization reaction process, emulsifier molecules are adsorbed on the surfaces of oil and water, are directionally arranged into a film and are between the oil phase and the water phase, so that the interfacial tension is reduced, the oil and the water are uniformly dispersed, and the aggregation of liquid drops is effectively prevented. Forming a water-in-oil-in-water slow-release air entraining outer membrane. The outermost layer is a water phase, so that the slow-release air entraining agent and the water reducing agent can be mutually dissolved. The water reducing agent can be stably dispersed in the water reducing agent, the middle oil phase is a copolymer of acrylic acid and polyalcohol acrylate, the copolymer is an outer film of the slow-release air entraining agent formed by free radical polymerization under the high-temperature condition, and the innermost water phase is a core dissolved with the rosin air entraining agent.
The invention also provides a preparation method of the slow-release air entraining agent, which can specifically adopt the following method, weighing 20-30 parts of air entraining components, dissolving the air entraining components in 40-60 parts of deionized water, simultaneously adding 0.5-1 part of initiator, stirring and dissolving to prepare aqueous phase liquid A. Weighing 10-20 parts of acrylic monomer, 0.3-0.8 part of polyol acrylate and 1-5 parts of emulsifier to prepare oil phase liquid B. Adding the oil phase liquid B into the water phase liquid A, and emulsifying for 5-10min under ultrasonic dispersion (speed of 5000-8000 r/min) to obtain water-oil emulsion; adding the water-oil emulsion into N 2 Or stirring and heating the mixture under the inert gas atmosphere, and heating the mixture to 60-90 ℃ for reaction for 4-7 hours to obtain the slow-release air entraining agent.
According to the preparation method of the slow-release air entraining agent, the acrylic monomer and the polyol acrylate are polymerized into the high-polyester slow-release outer membrane through the initiator, the air entraining components are wrapped by the high-polyester slow-release outer membrane through stirring and heating, and the high-polyester slow-release outer membrane can be hydrolyzed and broken under the alkaline condition of concrete to release the air entraining components, so that the effect of entraining air in the concrete is achieved.
The invention further provides a concrete state retention agent, which comprises the following raw materials in parts by weight: 200-300 parts of water reducing agent, 100-200 parts of slump retaining agent, 5-10 parts of water retaining agent, 0.5-1 part of air entraining agent, 5-10 parts of slow release air entraining agent, 1-3 parts of slow release water retaining agent, 20-30 parts of retarder and 446-668.5 parts of water; the slow release water-retaining agent comprises the following raw materials in parts by weight: 10 to 20 portions of acrylamide monomer, 30 to 40 portions of slow release monomer, 0.3 to 0.5 portion of initiator and 3500 to 4000 portions of water.
The water reducing agent can disperse cement particles, improve the workability of the cement particles, reduce unit water consumption and improve the fluidity of concrete mixtures. The slump retaining agent can keep the slump of concrete not to be lost quickly, has the effect of retarding, delaying the hydration and the condensation of cement and keeping the slump. The water-retaining agent has strong water absorption capacity, can effectively improve the initial cohesiveness of concrete, and improves the phenomena of segregation and bleeding. The air entraining agent can introduce a large amount of uniformly distributed, stable and closed micro bubbles during mixing, and improves the initial homogeneity, frost resistance, impermeability and durability of concrete. The retarder can prolong the hydration hardening time of cement, so that the fresh concrete can keep plasticity for a longer time, and more time is prepared for pumping and construction of the fresh concrete. Each of the above additives is commercially available.
The slow-release water-retaining agent can be prepared by adopting the raw material proportion and the method disclosed by the patent CN111285965A, the use of the slow-release water-retaining agent can lock the free water released in the later period, the bleeding problem in the later period is avoided, and the phenomenon that the initial viscosity of concrete is greatly increased due to the large use of the water-retaining agent in the initial period can be avoided. The high-polyester slow-release outer membrane of the slow-release air entraining agent can be hydrolyzed in an alkaline environment to gradually release the wrapped air entraining agent molecules, so that the air entraining agent is supplemented adaptively at the later stage of the concrete, the air content loss is compensated, and the air content is basically consistent with that of the initial stage.
The later state (after 1 h) of the large-flow concrete (also called 'pumping concrete', commonly used concrete pump for conveying and pouring, the slump is generally 21-23 cm, and the large-flow concrete has the characteristics of preventing segregation and bleeding, and preventing durability (including frost resistance) and smaller drying shrinkage rate), mainly has the problems of air-containing loss, poor water retention and the like, so that the phenomena of bleeding, serious slurry lower layer and stone leakage and the like exist in the later state of the concrete compared with the initial state, and the problems of difficult pumping of a construction site and the like are caused. According to the invention, the problems of later air loss, poor water retention and the like are solved by adding the slow-release air entraining agent and the slow-release water-retaining agent, and the concrete can reach 5h slump and expansion degree basically without loss by matching the additives, so that the construction requirements at different time periods are completely met.
The following describes in detail specific embodiments of the present invention.
Implementing group one:
in the following examples, a slow-release air entraining agent is added into concrete, and in comparative examples 1 to 3, no air entraining agent is added into the concrete, a common air entraining agent and the air entraining agent in patent CN113121147A are respectively added, the air content of the concrete is tested, the concrete is stirred for 30s before the test at intervals of 1h, the mixing ratio of the concrete adopts the C30 mixing ratio in Table 1, the mixing amount of the air entraining agent is 0.5 ten thousandth of a cementing material, and the initial air content and air content loss of different air entraining agents in the concrete are tested.
TABLE 1 C30 concrete mixing ratio
| Concrete label | Cement/Kg | Coal ash/Kg | sand/Kg | Stone/Kg | Water/Kg |
| C30 | 300 | 60 | 902 | 978 | 160 |
Example 1:
weighing 20 parts of sodium abietate air entraining agent, dissolving the sodium abietate air entraining agent in 40 parts of deionized water, simultaneously adding 0.5 part of ammonium ceric nitrate, stirring and dissolving to prepare aqueous phase liquid A. Weighing 10 parts of acrylic anhydride, 0.3 part of 1, 4-butanediol dimethacrylate, 0.5 part of span-20 and 0.5 part of tween-80 to obtain an oil phase liquid B. Adding the oil phase liquid B into the water phase liquid A, and emulsifying for 5min at the rotation speed of 5000r/min by ultrasonic dispersion to obtain water-oil emulsion; adding the water-oil emulsion into N 2 Stirring and heating the mixture in the atmosphere, and heating the mixture to 60 ℃ for reaction for 4 hours to obtain the slow-release air entraining agent. The slow-release air entraining agent of the embodiment is added into concrete with the mixing ratio shown in the table 1 and uniformly mixed.
Example 2:
weighing 20 parts of sodium abietate air entraining agent, dissolving the sodium abietate air entraining agent in 60 parts of deionized water, simultaneously adding 0.7 part of ammonium ceric nitrate, stirring and dissolving to prepare aqueous phase liquid A. Weighing 15 parts of methacrylic anhydride, 0.4 part of 1, 4-butanediol dimethacrylate, 1 part of span-20 and 1 part of tween-80 to obtain an oil phase liquid B. Adding the oil phase liquid B into the water phase liquid A, and emulsifying at 6000r/min for 5min by ultrasonic dispersion to obtain water-oil emulsion; adding the water-oil emulsion into N 2 Stirring and heating the mixture under the atmosphere, and heating the mixture to 65 ℃ for reaction for 5 hours to obtain the slow-release air entraining agent. The slow-release air entraining agent of the embodiment is added into concrete with the mixing ratio shown in the table 1 and uniformly mixed.
Example 3:
weighing 25 parts of sodium abietate air entraining agent, dissolving the sodium abietate air entraining agent in 50 parts of deionized water, simultaneously adding 0.8 part of ammonium cerium sulfate, stirring and dissolving to prepare aqueous phase liquid A. 30 parts of methyl methacrylate, 0.5 part of 1, 3-butanediol dimethacrylate, 1 part of span-20 and 1.5 parts of tween-80 are weighed to obtain an oil phase liquid B. Adding the oil phase liquid B into the water phase liquid A, and emulsifying for 5min at 7000r/min by ultrasonic dispersion to obtain water-oil emulsion; mixing the water and the oilEmulsion in N 2 Stirring and heating the mixture in the atmosphere, and heating the mixture to 80 ℃ for reaction for 4.5 hours to obtain the slow-release air entraining agent. The slow-release air entraining agent in the embodiment is added into concrete with the mixing proportion shown in the table 1 and uniformly mixed.
Comparative example 1: concrete without air entraining agent.
Comparative example 2: concrete adopting common air entraining agent.
Comparative example 3: an air entraining agent prepared by adopting the method of patent CN 113121147A.
Table 2 below is test data for each example and comparative example.
Table 2 comparison of air contents of concrete to which different air entraining agents were added (unit:%)
Table 2 shows that: the air content of each embodiment is increased along with the increase of time, because the air-entraining ingredients are gradually released after the slow-release outer membrane is hydrolyzed, so that the air content of the concrete is increased; in comparative example 1 in which no air entraining agent was added, the air content was very small throughout; the initial high air content of the comparative example 2 added with the common air entraining agent is obviously reduced along with the increase of time, and the air content is obviously lost with the lapse of time; the gas content of comparative example 3 added in patent CN113121147A is kept well within 3h, and the gas content loss is obvious when the gas content exceeds 3 h.
And (2) implementing a group two:
the slow-release air entraining agent and the slow-release water retaining agent of the following embodiments are prepared by the method, and the retarder is at least one of sugar, sodium gluconate, sodium tripolyphosphate, sodium hexametaphosphate, sodium citrate and sodium metabisulfite. The rest additives are sold by Yanjiazhuang Mingchenyu building material company, the water reducing agent adopts the water reducing agent with the model P3, the slump retaining agent adopts the slump retaining agent with the models C8 and C9 to be mixed, the water retaining agent is the water retaining agent with the model B3, and the air entraining agent is the air entraining agent with the model YQ-1.
Example 4:
preparing a slow-release air entraining agent:
the slow release type air entraining agent of example 1 was used.
Preparing a slow-release water-retaining agent:
weighing 10 parts of acrylamide and 30 parts of hydroxyethyl acrylate, dissolving in 200 parts of deionized water, pouring the solution into a three-neck flask, stirring, heating to 55 ℃, adding 0.3 part of azobisisobutyronitrile into the three-neck flask, reacting at 55 ℃ for 10 hours, and diluting with deionized water to obtain a colorless transparent solution with the solid content of 1.5%, namely the slow-release water-retaining agent.
Preparation of concrete state retention agent:
weighing 200g of water reducing agent P3, 50g of slump retaining agent C8, 50g of slump retaining agent C9,5g of water retaining agent B3, 20g of sugar, 10g of sodium gluconate and 5g of slow-release water retaining agent, adding deionized water to ensure that the whole mass is 1000g, starting stirring, stirring for 10min, adding 0.5g of air entraining agent YQ-1 and 1g of slow-release air entraining agent after uniformly stirring, continuing stirring for 3min, and stopping stirring to obtain a finished product.
Example 5:
preparing a slow-release air entraining agent:
the slow release air entraining agent of example 2 was used.
Preparing a slow-release water-retaining agent:
weighing 15 parts of 2-acrylamide-2-methylpropanesulfonic acid and 35 parts of hydroxypropyl acrylate, dissolving in 250 parts of deionized water, pouring the solution into a three-neck flask, stirring, heating to 60 ℃, adding 0.5 part of azobisisobutyramidine hydrochloride into the three-neck flask, reacting at 60 ℃ for 12 hours, and diluting with deionized water to obtain a colorless transparent solution with the solid content of 1.5%, namely the slow-release water-retaining agent.
Preparation of concrete state retention agent:
weighing 250g of water reducing agent P3, 50g of slump retaining agent C8, 80g of slump retaining agent C9,8g of water retaining agent B3, 10g of sugar, 20g of sodium tripolyphosphate and 10g of slow-release water retaining agent, adding deionized water to ensure that the whole mass is 1000g, starting stirring, stirring for 10min, adding 0.6g of air entraining agent YQ-1 and 2g of slow-release air entraining agent after uniformly stirring, continuing stirring for 3min, and stopping stirring to obtain a finished product.
Example 6:
preparing a slow-release air entraining agent:
the slow release air entraining agent of example 3 was used.
Preparing a slow-release water-retaining agent:
weighing 20 parts of 2-acrylamide-2-methylpropanesulfonic acid and 40 parts of hydroxypropyl methacrylate, dissolving in 250 parts of deionized water, pouring the solution into a three-neck flask, stirring, heating to 60 ℃, adding 0.4 part of azobisisobutyrimidazoline hydrochloride into the three-neck flask, reacting at 65 ℃ for 10 hours, and diluting with deionized water to obtain a colorless transparent solution with the solid content of 1.5%, namely the slow-release water-retaining agent.
Preparation of concrete state retention agent:
230g of water reducer P3, 40g of slump retainer C8, 90g of slump retainer C9, 10g of water retainer B3, 10g of sodium gluconate, 15g of sodium citrate and 5g of slow-release water retainer are weighed and added into a 2L reaction kettle, deionized water is added to ensure that the total mass is 1000g, stirring is started for 10min, 1g of air entraining agent YQ-1 and 1g of slow-release air entraining agent are added after uniform stirring, stirring is continued for 3min, and the stirring is stopped to obtain a finished product.
Example 7:
preparing a slow-release air entraining agent:
weighing 30 parts of sodium abietate air-entraining agent, dissolving in 60 parts of deionized water, simultaneously adding 1 part of ammonium ceric sulfate, stirring and dissolving to prepare aqueous phase liquid A. 15 parts of methyl propylene ethyl ester, 0.7 part of 1, 3-propylene glycol dimethacrylate, 2 parts of span-20 and 2 parts of tween-80 are weighed to obtain an oil phase liquid B. Adding the oil phase liquid B into the water phase liquid A, and emulsifying at 8000r/min for 5min by ultrasonic dispersion to obtain water-oil emulsion; adding the water-oil emulsion into N 2 Stirring and heating the mixture in the atmosphere, and heating the mixture to 70 ℃ for reaction for 6 hours to obtain the slow-release air entraining agent.
Preparing a slow-release water-retaining agent:
weighing 15 parts of acrylamide and 35 parts of hydroxyethyl methacrylate, dissolving in 250 parts of deionized water, pouring the solution into a three-neck flask, stirring, heating to 55 ℃, adding 0.5 part of azobisisobutyronitrile into the three-neck flask, reacting at 55 ℃ for 12 hours, and diluting with deionized water to obtain a colorless transparent solution with the solid content of 1.5%, namely the slow-release water-retaining agent.
Preparation of concrete state retention agent:
weighing 280g of water reducer P3, 40g of slump retainer C8, 100g of slump retainer C9, 10g of water retaining agent B3, 10g of sugar, 10g of sodium citrate, 10g of sodium metabisulfite and 10g of slow-release water retaining agent, adding into a 2L reaction kettle, adding deionized water to ensure that the whole mass is 1000g, starting stirring, stirring for 10min, adding 0.5g of air entraining agent YQ-1 and 2g of slow-release air entraining agent after uniformly stirring, continuing stirring for 3min, and stopping stirring to obtain a finished product.
Comparative example 4:
in example 4, the slow-release air entraining agent component is not added, and other components are the same as those in example 4.
Comparative example 5:
in example 4, the other components are the same as in example 4 except that the component of the sustained release water retaining agent is not added.
The following are the performance tests of the invention:
the cement is NZ P.O.42.5 cement; the fly ash is second-grade fly ash; the sand is crushed stone with 5-31.5mm continuous gradation of artificial and mechanical stones, and concrete performance test is carried out according to the standard of the test method of ordinary concrete mechanical properties (GB/T50080-2002). The concrete evaluation was carried out by using the products of the above four groups of examples, comparative example 4 and comparative example 5, and the mixing ratio test was carried out by using C30, and the initial concrete expansion degree was made to be in the range of 580 to 600mm by controlling the mixing amount of the concrete state retaining agent, as shown in Table 3, the performance test was as shown in Table 4, and the concrete state was as shown in Table 5.
TABLE 3 C30 concrete mixing ratio
| Concrete signNumber (C) | Cement/Kg | Coal ash/Kg | sand/Kg | Stone/Kg | Water/Kg |
| C30 | 300 | 60 | 902 | 978 | 160 |
TABLE 4 concrete Performance test results
TABLE 5 concrete State description
| Number of | Comparative example 4 | Comparative example 5 | Example 4 | Example 5 | Example 6 | Example 7 |
| State tracing The above-mentioned | 0H concrete Rich in pulp, bag Wrapped without secretion Water phenomenon, no Leaked stone sinking slurry Phenomenon after 1H The loss of the gas content is reduced, has the functions of bleeding and dew Rock and heap core Elephant, 4H post-expansion Loss of spread Is obvious. | 0H concrete Rich in pulp, bag Wrapping well without secretion Water phenomenon, no Leaked stone sinking slurry Phenomenon after 1H Has severe secretion Water, core piling Elephant, containing qi Loss, 4H Degree of post-expansion The loss was significant. | 0-5H internal mixing Concrete slurry Fuji, bag Good quality without bleeding Phenomenon and no leakage Stone subsides and slurry Like, each time Segment status and initial agreement | 0-5H internal mixing Concrete slurry Rich and package Good quality without bleeding Phenomenon and no leakage Settling of stone Like, each time Segment status and initial agreement | 0-5H internal mixing Concrete slurry Rich and package Good quality without bleeding Phenomenon and no leakage Stone subsides and slurry Like, each time Segment status and initial agreement | 0-5H internal concrete Rich in pulp and wrapping Good and no bleeding Elephant and non-leaking stone mud Phenomenon, time periods Status and initial one To make |
And (4) conclusion: examples 4, 5, 6 and 7 have basically consistent concrete expansion, slump, air content and bleeding rate in 5H, and have no obvious change in the whole state.
The difference between the comparative example 4 and the example 4 is that the slow-release air entraining agent is not added, so that the air content loss of the concrete is obvious after 1H, and the concrete is easy to bleed due to the air content loss, so that the state of the whole concrete is obviously changed, and the phenomena of bleeding, core piling and stone leakage exist. The slow-release air entraining agent is beneficial to reducing the bleeding and air loss in the later period of the concrete and keeping the state of the concrete for a longer time.
The difference between the comparative example 5 and the example 4 is that the slow release type water retaining agent is not added, so that the bleeding phenomenon of the concrete after 1H is serious, free water released in the later period does not have more water retaining agents to control the free water in the concrete, so that the concrete slurry is insufficient in the lower layer of the slurry body, and the stone leakage and core stacking phenomenon are serious. The slow release type water retention agent is beneficial to reducing bleeding in the later period of concrete.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that, in the above embodiments, the various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present invention does not separately describe various possible combinations.
Claims (8)
1. A slow-release air entraining agent is characterized in that: the active ingredients of the slow-release air entraining agent comprise: the air entraining agent comprises an air entraining component and a slow release outer membrane for coating the air entraining component, wherein the slow release outer membrane is high polyester which can be hydrolyzed and broken under alkaline conditions; the air entraining component is a rosin air entraining agent, and the slow release outer membrane is a copolymer of an acrylic monomer and polyalcohol acrylate;
the preparation raw materials of the slow-release air entraining agent comprise, by weight: 20-30 parts of rosin air entraining agent, 10-20 parts of acrylic monomer, 0.3-0.8 part of polyol acrylate, 1-5 parts of emulsifier, 0.5-1 part of initiator and 40-60 parts of water.
2. The slow release air entraining agent according to claim 1 wherein: the rosin air entraining agent comprises sodium abietate and/or potassium abietate.
3. The slow release air entraining agent according to claim 1 wherein: the acrylic monomer comprises at least one of acrylic anhydride, methacrylic anhydride, methyl methacrylate and ethyl methacrylate.
4. The slow-release air entraining agent according to claim 1, characterized in that: the polyalcohol acrylate comprises at least one of 1, 4-butanediol dimethacrylate, 1, 3-butanediol dimethacrylate, ethylene glycol dimethacrylate and 1, 3-propylene glycol dimethacrylate.
5. The slow release air entraining agent according to claim 1 wherein: the emulsifier comprises sorbitan fatty acid ester and polyoxyethylene sorbitan fatty acid ester.
6. The slow release air entraining agent according to any one of claims 1 to 5 wherein: the initiator includes at least one of cerium ammonium nitrate and cerium ammonium sulfate.
7. A method for preparing the slow-release air entraining agent according to any one of claims 1 to 6, characterized in that:
adding an air entraining component and an initiator into water, stirring and dissolving to prepare aqueous phase liquid A;
mixing acrylic monomers and polyol acrylate to prepare an oil phase liquid B;
mixing the oil phase liquid B, the water phase liquid A and an emulsifier, and emulsifying under ultrasonic dispersion to obtain a water-oil emulsion;
adding the water-oil emulsion into N 2 Or stirring and heating to 60-90 ℃ under the inert gas atmosphere, and fully reacting to obtain the slow-release air entraining agent.
8. A concrete state retaining agent characterized by: the concrete state retention agent comprises the following raw materials in parts by weight: 200-300 parts of water reducing agent, 100-200 parts of slump retaining agent, 5-10 parts of water retaining agent, 0.5-1 part of air entraining agent, 5-10 parts of slow release air entraining agent according to any one of claims 1-6, 1-3 parts of slow release water retaining agent, 20-30 parts of retarder and 446-668.5 parts of water;
the slow release water-retaining agent comprises the following raw materials in parts by weight: 10 to 20 portions of acrylamide monomer, 30 to 40 portions of slow release monomer, 0.3 to 0.5 portion of initiator and 3500 to 4000 portions of water.
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| CN202210796850.1A CN114873949B (en) | 2022-07-08 | 2022-07-08 | Slow-release air entraining agent, preparation method thereof and concrete state retaining agent |
| PCT/CN2023/089520 WO2024007681A1 (en) | 2022-07-08 | 2023-04-20 | Slow-release air-entraining agent, preparation method therefor and concrete state retaining agent |
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| CN114873949B (en) * | 2022-07-08 | 2022-10-14 | 石家庄市长安育才建材有限公司 | Slow-release air entraining agent, preparation method thereof and concrete state retaining agent |
| CN115259731A (en) * | 2022-08-17 | 2022-11-01 | 博特新材料泰州有限公司 | Slow-release long-acting air entraining material and preparation method and application thereof |
| CN115947566B (en) * | 2023-03-11 | 2023-08-08 | 石家庄市长安育才建材有限公司 | Additive for steam curing-free precast concrete and preparation method thereof |
| CN116496022A (en) * | 2023-06-27 | 2023-07-28 | 石家庄市长安育才建材有限公司 | Thickening agent for coarse sand concrete and preparation method thereof |
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