Low-sensitivity concrete slump retaining agent and preparation method thereof

Abstract

The present application relates to the technical field of building admixtures, and particularly relates to a low-sensitivity concrete slump retaining agent and a preparation method thereof. The low-sensitivity concrete slump retaining agent comprises, by weight, 300-440 parts of polyether monomer, 650-750 parts of water, 1-6 parts of chain transfer agent, 18-50 parts of olefinic acid monomer, 28-60 parts of olefinic ester monomer, 3-5.5 parts of 4A zeolite, 1.8-5.6 parts of initiator, 0.4-1.2 parts of reducing agent and 12-19 parts of flaky alkali. In the preparation method of the low-sensitivity concrete slump retaining agent, the 4A zeolite is ultrasonically dispersed into the olefinic monomer solution, the reaction conversion rate is improved by using the catalytic action of the 4A zeolite during the dropping process, the polymeric polycarboxylic acid generated in the reaction is stably adsorbed in the cavities of the 4A zeolite by using the multi-cavity characteristics of the 4A zeolite, the adsorption of other materials is reduced, the sensitivity is reduced, the dispersibility of the slump retaining agent to the slurry system is improved under the synergistic action of the 4A zeolite, and the water-reducing effect in the concrete is enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building admixtures, in particular to a low-sensitivity concrete slump retaining agent and a preparation method thereof. BACKGROUND

[0002] At present, the research on polycarboxylic acid admixtures at home and abroad mainly focuses on further improving the water-reducing and slump retaining performance, or adding new properties such as viscosity reduction, workability, enhancement, and mud resistance. As an admixture variety with the second largest amount of use in concrete admixtures, concrete slump retaining agent plays a very important role in concrete admixtures. However, in recent years, on the one hand, the requirements for concrete quality of major projects are becoming higher and higher, but on the other hand, high-quality sand resources are gradually scarce, which makes the requirements for slow-release concrete slump retaining agent higher and higher. The quality of machine-made fine sand used in Henan region is poor, and the performance of different batches of sand is unstable, with high mud content and high MB value, which leads to the problem of excessive concrete loss over time.

[0003] There are many types of cement in the southwest region, and the water requirement ratio and the adsorption of admixtures differ greatly. The sand is mainly machine-made sand, and the mud content and stone powder content in the machine-made sand are strictly controlled. Generally, wet sand preparation process is adopted. In order to meet the requirements of mud content and stone powder content, a large amount of flocculating agent is used in the sand washing water treatment process of machine-made sand, which leads to the residual flocculating agent in the machine-made sand, and the content fluctuates greatly. The fluctuation of cementitious materials and machine-made sand and other materials has a great influence on the application of admixtures, and the production loss and lag occur alternately.

[0004] The sensitivity of concrete slump retaining agent to external fluctuations will affect its spread. Therefore, it is of great significance to develop a low-sensitivity concrete slump retaining agent. SUMMARY

[0005] In order to solve the problem of the influence of mud adsorption on concrete slump retaining agent mentioned in the background, the present application provides a low-sensitivity concrete slump retaining agent. According to weight parts, polyether monomer 300-440 parts, water 650-750 parts, 1-6 parts of chain transfer agent, 18-50 parts of oleic acid monomer, 28-60 parts of oleic acid monomer, 4A zeolite 3-5.5 parts, initiator 1.8-5.6 parts, reducing agent 0.4-1.2 parts, and flake alkali 12-19 parts.

[0006] On the basis of the above technical solution, further, the polyether monomer is at least one of methyl allyl polyoxyethylene ether or iso-pentyl polyoxyethylene ether or vinyl polyoxyethylene ether.

[0007] On the basis of the above technical scheme, further, the average molecular weight of the methyl alkenyl polyoxyethylene ether is 1964-3592, and its structural formula is CH2=CH(CH3)CH2O(CH2CH2O)nH, wherein n=43-80.

[0008] On the basis of the above technical scheme, further, the average molecular weight of the isopentenyl polyoxyethylene ether is 1980-3608, and its structural formula is (CH3)2C=CHCH2O(CH2CH2O)nH, wherein n=43-80.

[0009] On the basis of the above technical scheme, further, the average molecular weight of the vinyl polyoxyethylene ether is 1893-3653, and its structural formula is C6H 12 O3(CH2CH2O)nH, wherein n=40-80.

[0010] On the basis of the above technical scheme, further, the chain transfer agent is one or more combinations of isopropyl alcohol, phosphorous acid and hypophosphorous acid and its salt (sodium hypophosphite, potassium hypophosphite, etc.), sulfurous acid, bisulfite, dithionite and metabisulfite and its salt (sodium sulfite, sodium bisulfite, preferably sodium dithionite, potassium sulfite, sodium metabisulfite, potassium bisulfite, potassium dithionite, potassium metabisulfite, etc.), mercaptoethanol, mercapto glycerol, mercapto acetic acid, mercapto propionic acid, 2-mercapto propionic acid, 3-mercapto propionic acid, thiomalic acid, 2-mercapto ethanesulfonic acid and its salt.

[0011] On the basis of the above technical scheme, further, the initiator is one or more combinations of hydrogen peroxide, potassium or sodium persulfate, ammonium persulfate, azobisisobutyronitrile.

[0012] On the basis of the above technical scheme, further, the reducing agent is one or more combinations of vitamin C, oxalic acid, ferrous sulfate, cuprous sulfate, oxalic acid, sodium bisulfite, sodium sulfite, glucose, fructose, ethylenediamine, diphenylamine, sodium or potassium monohydrogen phosphate.

[0013] On the basis of the above technical scheme, further, the olefinic acid monomer is at least one of acrylic acid, crotonic acid, citraconic acid, maleic acid, methacrylic acid, itaconic acid, fumaric acid, etc., and monovalent metal salt, divalent preferably its metal salt, ammonium salt and organic amine salt, etc., or at least one of its anhydride;

[0014] The olefinic ester monomer is at least one of hydroxymethyl acrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.

[0015] The application also provides a preparation method of the low-sensitivity concrete slump retaining agent, comprising the following steps:

[0016] Take 3-5.5 parts by weight of 4A zeolite and 18-50 parts by weight of alkenyl monomer, 28-60 parts by weight of alkenyl monomer, 140-170 parts by weight of water into the reaction kettle, open the high-power industrial continuous flow energy type ultrasonic disperser, continue to ultrasonic for 2-3h, then 4A zeolite-alkenyl monomer dispersion liquid is obtained;

[0017] 300-440 parts by weight of polyether monomer and 300-400 parts by weight of water are added into the reaction kettle, and the mixture is stirred, dissolved and mixed at 15-45℃, and 1.8-5.6 parts by weight of initiator is added; the above polyether monomer is methyl allyl polyoxyethylene ether or iso-pentenyl polyoxyethylene ether or vinyl polyoxyethylene ether to obtain mixture A;

[0018] Solution one: 1-6 parts by weight of chain transfer agent, 0.4-1.2 parts by weight of reducing agent, 160-180 parts by weight of water are added in sequence; solution two: the obtained 4A zeolite-alkenyl monomer dispersion liquid;

[0019] After dropping for 1-3.5h, aging reaction is carried out at below 55℃ for 1-2h, and then neutralized to pH=5.8-6.8 with alkali solution, so that the concrete slump retaining agent is prepared.

[0020] The low sensitivity concrete slump retaining agent provided by the application can improve the reaction conversion rate by using the catalytic effect of 4A zeolite, and the poly carboxylic acid polymer generated by the reaction is stably adsorbed in the cavity of 4A zeolite by using the multi-cavity characteristics of 4A zeolite, thereby reducing the adsorption of other materials and reducing the sensitivity. Under the synergistic effect of 4A zeolite, the dispersibility of the slump retaining agent to the paste system is improved, and the water-reducing effect in concrete is enhanced.

[0021] In the preparation method of the low sensitivity concrete slump retaining agent provided by the application, 4A zeolite is ultrasonically dispersed into an alkenyl monomer solution, and the reaction conversion rate is improved by using the catalytic effect of 4A zeolite during the dropping process. Meanwhile, the poly carboxylic acid polymer generated by the reaction is stably adsorbed in the cavity of 4A zeolite by using the multi-cavity characteristics of 4A zeolite, thereby reducing the adsorption of other materials and reducing the sensitivity. Under the synergistic effect of 4A zeolite, the stability of the slump retaining agent to the paste system is improved, and the slump retaining effect in concrete is enhanced, so that a low sensitivity concrete slump retaining agent is finally obtained.

[0022] Other features and benefits of the present application will be set forth in the detailed description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. The objectives and other advantages of the present application can be realized and attained by the structure particularly pointed out in the written description and claims. DETAILED DESCRIPTION

[0023] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. The technical features designed in the different embodiments of the present application can be combined with each other as long as they do not conflict with each other. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0024] In the description of the present application, it should be noted that all the terms (including technical terms and scientific terms) used in the present application have the same meanings as those generally understood by the ordinary skilled person in the field to which the present application belongs, and should not be understood as the limitation of the present application; it should be further understood that the terms used in the present application should be understood as having the same meanings as those of the terms in the context of the present application and the related field, and should not be understood in an idealized or overly formal sense, unless defined explicitly in the present application.

[0025] The present application provides the following examples and comparative examples.

[0026] In the following examples and comparative examples, the average molecular weight of the methyl allyl polyoxyethylene ether is 1964-3592, and the structural formula is CH2=CH(CH3)CH2O(CH2CH2O)nH, wherein n=43-80. The average molecular weight of the iso-pentenyl polyoxyethylene ether is 1980-3608, and the structural formula is (CH3)2C=CHCH2O(CH2CH2O)nH, wherein n=43-80. The average molecular weight of the vinyl polyoxyethylene ether is 1893-3653, and the structural formula is C6H 12 O3(CH2CH2O)nH, wherein n=40-80.

[0027] Example 1

[0028] A low-sensitivity concrete slump retaining agent and a preparation method thereof are prepared from the following raw material components by weight: methyl allyl polyoxyethylene ether 320 parts by weight, water 650 parts by weight, isopropyl alcohol 3.5 parts by weight, acrylic acid 23 parts by weight, hydroxyethyl acrylate 40 parts by weight, hydrogen peroxide 2.8 parts by weight, vitamin C 0.8 parts by weight, 4A zeolite 3.3 parts by weight, and sodium carbonate 8 parts by weight.

[0029] The specific preparation method includes the following steps:

[0030] (1) Take 3.3 parts by weight of 4A zeolite, 23 parts by weight of acrylic acid, 40 parts by weight of hydroxyethyl acrylate and 160 parts by weight of water into the reaction kettle, open the high-power industrial continuous flow polycentric ultrasonic disperser, and continuously ultrasonic for 2h, that is, 4A zeolite-olefin monomer dispersion liquid;

[0031] (2) Add 320 parts by weight of methyl allyl polyoxyethylene ether and 330 parts by weight of water into the reaction kettle, stir and mix at room temperature 25℃, and add 2.8 parts by weight of hydrogen peroxide;

[0032] (3) To the material obtained in step (2), solution one: 3.5 parts by weight of isopropyl alcohol, 0.8 parts by weight of vitamin C, 160 parts by weight of water; Solution two: 4A zeolite-olefin monomer dispersion liquid obtained in (1) is added dropwise; After 2h, aging reaction is carried out at 55℃ below for 1h, and then neutralized with alkali to pH=6.2, to obtain the low sensitive concrete slump retaining agent.

[0033] Example 2

[0034] A low sensitive concrete slump retaining agent and its preparation method, which is made of the following raw material components by weight: methyl allyl polyoxyethylene ether 350 parts by weight, water 670 parts by weight, mercaptoacetic acid 2.7 parts by weight, methacrylic acid 34 parts by weight, hydroxypropyl acrylate 42 parts by weight, hydrogen peroxide 3.0 parts by weight, vitamin C 0.8 parts by weight, 4A zeolite 3.4 parts by weight, and flake alkali 14 parts by weight.

[0035] The specific preparation method comprises the following steps:

[0036] (1) Take 3.4 parts by weight of 4A zeolite, 34 parts by weight of methacrylic acid, 42 parts by weight of hydroxypropyl acrylate and 160 parts by weight of water into the reaction kettle, open the high-power industrial continuous flow polycentric ultrasonic disperser, and continuously ultrasonic for 2h, that is, 4A zeolite-olefin monomer dispersion liquid;

[0037] (2) Add 350 parts by weight of methyl allyl polyoxyethylene ether and 350 parts by weight of water into the reaction kettle, stir and mix at room temperature 25℃, and add 2.8 parts by weight of hydrogen peroxide;

[0038] (3) To the material obtained in step (2), solution one: 2.7 parts by weight of mercaptoacetic acid, 0.8 parts by weight of vitamin C, 160 parts by weight of water; Solution two: 4A zeolite-olefin monomer dispersion liquid obtained in (1) is added dropwise; After 2.5h, aging reaction is carried out at 55℃ below for 1h, and then neutralized with alkali to pH=6.1, to obtain the low sensitive concrete slump retaining agent.

[0039] Example 3

[0040] A low sensitivity type concrete slump retaining agent and a preparation method thereof are prepared from the following raw material components by weight: iso-pentenyl polyoxyethylene ether 380 parts by weight, water 690 parts by weight, mercaptoacetic acid 2.9 parts by weight, acrylic acid 24 parts by weight, hydroxyethyl acrylate 40 parts by weight, hydrogen peroxide 3.0 parts by weight, ethylenediamine 1.6 parts by weight, 4A zeolite 3.8 parts by weight, and flake alkali 17 parts by weight.

[0041] The specific preparation method includes the following steps:

[0042] (1) 4.2 parts by weight of 4A zeolite, 32 parts by weight of itaconic acid, 44 parts by weight of hydroxypropyl acrylate, and 160 parts by weight of water are added to a reaction kettle, a high-power industrial continuous flow poly-energy type ultrasonic disperser is opened, and continuous ultrasonic is performed for 2 hours, that is, a 4A zeolite-olefin monomer dispersion liquid;

[0043] (2) 360 parts by weight of iso-pentenyl polyoxyethylene ether and 350 parts by weight of water are added to the reaction kettle, stirred and mixed to dissolve at 35°C, and 2.6 parts by weight of hydrogen peroxide is added;

[0044] (3) Solution one: 2.9 parts by weight of mercaptoacetic acid, 1.6 parts by weight of ethylenediamine, and 160 parts by weight of water are sequentially and dropwise added to the material obtained in step (2); solution two: the 4A zeolite-olefin monomer dispersion liquid obtained in (1); after dropwise adding for 3 hours, aging reaction is performed at below 55°C for 1 hour, and then neutralized with alkali to pH = 6.2, thereby obtaining the low sensitivity type concrete slump retaining agent.

[0045] Example 4

[0046] A low sensitivity type concrete slump retaining agent and a preparation method thereof are prepared from the following raw material components by weight: iso-pentenyl polyoxyethylene ether 360 parts by weight, water 670 parts by weight, mercaptoethanol 2.2 parts by weight, itaconic acid 32 parts by weight, 44 parts by weight of hydroxypropyl acrylate, hydrogen peroxide 2.6 parts by weight, vitamin C 0.8 parts by weight, 4A zeolite 4.2 parts by weight, and flake alkali 18 parts by weight.

[0047] The specific preparation method includes the following steps:

[0048] (1) 4.2 parts by weight of 4A zeolite, 32 parts by weight of itaconic acid, 44 parts by weight of hydroxypropyl acrylate, and 160 parts by weight of water are added to a reaction kettle, a high-power industrial continuous flow poly-energy type ultrasonic disperser is opened, and continuous ultrasonic is performed for 2 hours, that is, a 4A zeolite-olefin monomer dispersion liquid;

[0049] (2) 360 parts by weight of iso-pentenyl polyoxyethylene ether and 350 parts by weight of water are added to the reaction kettle, stirred and mixed to dissolve at 35°C, and 2.6 parts by weight of hydrogen peroxide is added;

[0050] (3) to the material obtained in step (2), solution one: 2.2 parts by weight of mercaptoethanol, 0.8 parts by weight of vitamin C, 160 parts by mass of water; solution two: the 4A zeolite-olefin monomer dispersion liquid obtained in (1) is added dropwise; after 3 h of dropwise addition, an aging reaction is carried out at below 55°C for 1 h, and then neutralized with alkali to pH = 6.2, to obtain the low-sensitivity concrete slump retaining agent.

[0051] Example 5

[0052] A low-sensitivity concrete slump retaining agent and a preparation method thereof are prepared from the following raw material components by weight: isopentenyl polyoxyethylene ether 400 parts by weight, water 710 parts by weight, mercaptoethanol 2.4 parts by weight, acrylic acid 24 parts by weight, 42 parts by weight of hydroxyethyl acrylate, hydrogen peroxide 2.8 parts by weight, vitamin C 0.9 parts by weight, 4A zeolite 4.5 parts by weight, and flake alkali 19 parts by weight.

[0053] The specific preparation method includes the following steps:

[0054] (1) 4.5 parts by weight of 4A zeolite, 24 parts by weight of acrylic acid, 42 parts by weight of hydroxyethyl acrylate, and 160 parts by weight of water are added to a reaction kettle, a high-power industrial continuous flow energy-type ultrasonic disperser is opened, and continuous ultrasonic dispersion is carried out for 2 h, to obtain a 4A zeolite-olefin monomer dispersion liquid;

[0055] (2) 400 parts by weight of isopentenyl polyoxyethylene ether and 390 parts by weight of water are added to a reaction kettle, and stirred and dissolved at 35°C, and 2.8 parts by weight of hydrogen peroxide is added;

[0056] (3) to the material obtained in step (2), solution one: 2.4 parts by weight of mercaptoethanol, 0.9 parts by weight of vitamin C, 160 parts by mass of water; solution two: the 4A zeolite-olefin monomer dispersion liquid obtained in (1) is added dropwise; after 3 h of dropwise addition, an aging reaction is carried out at below 55°C for 1 h, and then neutralized with alkali to pH = 6.2, to obtain the low-sensitivity concrete slump retaining agent.

[0057] Example 6

[0058] A low-sensitivity concrete slump retaining agent and a preparation method thereof are prepared from the following raw material components by weight: isopentenyl polyoxyethylene ether 400 parts by weight, water 710 parts by weight, mercaptoethanol 2.4 parts by weight, acrylic acid 24 parts by weight, 42 parts by weight of hydroxyethyl acrylate, hydrogen peroxide 2.8 parts by weight, vitamin C 0.9 parts by weight, 4A zeolite 4.5 parts by weight, and flake alkali 19 parts by weight.

[0059] The specific preparation method includes the following steps:

[0060] (1) Take 4.2 parts by weight of 4A zeolite, 22 parts by weight of acrylic acid, 44 parts by weight of hydroxyethyl acrylate, and 160 parts by weight of water into a reaction kettle, open the high-power industrial continuous flow energy-type ultrasonic disperser, and continuously ultrasonic for 2 h, that is, 4A zeolite-olefin monomer dispersion liquid;

[0061] (2) Add 320 parts by weight of vinyl polyoxyethylene ether and 310 parts by weight of water into the reaction kettle, mix and dissolve at 35°C, and add 2.2 parts by weight of hydrogen peroxide;

[0062] (3) To the material obtained in step (2), solution one: 2.8 parts by weight of mercaptoethanol, 0.7 parts by weight of vitamin C, 160 parts by weight of water; solution two: 4A zeolite-olefin monomer dispersion liquid obtained in (1) are added dropwise; after 3 h of dropping, aging reaction is carried out at below 55°C for 1 h, and then neutralized with alkali to pH = 6.2, to obtain the low sensitivity concrete slump retaining agent.

[0063] Example 7

[0064] A low sensitivity concrete slump retaining agent and a preparation method thereof are prepared from the following raw material components by weight: vinyl polyoxyethylene ether 380 parts by weight, water 690 parts by weight, sodium monohydrogen phosphate 4.8 parts by weight, acrylic acid 26 parts by weight, 52 parts by weight of hydroxymethyl acrylate, hydrogen peroxide 2.2 parts by weight, vitamin C 0.7 parts by weight, 4A zeolite 4.2 parts by weight, and flake alkali 17 parts by weight.

[0065] The specific preparation method comprises the following steps:

[0066] (1) Take 4.2 parts by weight of 4A zeolite, 26 parts by weight of acrylic acid, 52 parts by weight of hydroxymethyl acrylate, and 160 parts by weight of water into a reaction kettle, open the high-power industrial continuous flow energy-type ultrasonic disperser, and continuously ultrasonic for 2 h, that is, 4A zeolite-olefin monomer dispersion liquid;

[0067] (2) Add 380 parts by weight of vinyl polyoxyethylene ether and 370 parts by weight of water into the reaction kettle, mix and dissolve at 35°C, and add 2.2 parts by weight of hydrogen peroxide;

[0068] (3) To the material obtained in step (2), solution one: 4.8 parts by weight of sodium monohydrogen phosphate, 0.7 parts by weight of vitamin C, 160 parts by weight of water; solution two: 4A zeolite-olefin monomer dispersion liquid obtained in (1) are added dropwise; after 3 h of dropping, aging reaction is carried out at below 55°C for 1 h, and then neutralized with alkali to pH = 6.2, to obtain the low sensitivity concrete slump retaining agent.

[0069] Comparative Example 1

[0070] A commercially available PSP-100 model polycarboxylic acid slump retaining agent is used.

[0071] Comparative Example 2

[0072] A commercially available polycarboxylic acid slump retaining agent of model KH-218 was used.

[0073] Comparative Example 3

[0074] A low-sensitivity concrete slump retaining agent and a preparation method thereof are prepared from the following raw material components by weight: iso-pentenyl polyoxyethylene ether 400 parts by weight, water 710 parts by weight, mercaptoethanol 2.4 parts by weight, acrylic acid 24 parts by weight, 42 parts by weight of hydroxyethyl acrylate, hydrogen peroxide 2.8 parts by weight, vitamin C 0.9 parts by weight, conventional zeolite 4.5 parts by weight, and tablet alkali 19 parts by weight.

[0075] The specific preparation method includes the following steps:

[0076] (1) 4.5 parts by weight of conventional zeolite, 24 parts by weight of acrylic acid, 42 parts by weight of hydroxyethyl acrylate, and 160 parts by weight of water are added to a reaction kettle, a high-power industrial continuous flow energy-type ultrasonic disperser is turned on, and continuous ultrasonic dispersion is performed for 2 hours, thereby obtaining a conventional zeolite-olefin monomer dispersion liquid;

[0077] (2) 400 parts by weight of iso-pentenyl polyoxyethylene ether and 390 parts by weight of water are added to the reaction kettle, and stirring, mixing, and dissolving are performed at 35°C, and 2.8 parts by weight of hydrogen peroxide is added;

[0078] (3) Solution one: 2.4 parts by weight of mercaptoethanol, 0.9 parts by weight of vitamin C, and 160 parts by weight of water are sequentially and dropwise added to the material obtained in step (2); solution two: the conventional zeolite-olefin monomer dispersion liquid obtained in (1); after dropwise addition for 3 hours, aging reaction is performed at 55°C or below for 1 hour, and then neutralization is performed with alkali until the pH is 6.2, thereby obtaining the low-sensitivity concrete slump retaining agent.

[0079] Comparative Example 4

[0080] A low-sensitivity concrete slump retaining agent and a preparation method thereof are prepared from the following raw material components by weight: iso-pentenyl polyoxyethylene ether 400 parts by weight, water 710 parts by weight, mercaptoethanol 2.4 parts by weight, acrylic acid 24 parts by weight, 42 parts by weight of hydroxyethyl acrylate, hydrogen peroxide 2.8 parts by weight, vitamin C 0.9 parts by weight, 4A zeolite 2 parts by weight, and tablet alkali 19 parts by weight.

[0081] The specific preparation method includes the following steps:

[0082] (1) Take 2 parts by weight of 4A zeolite, 24 parts by weight of acrylic acid, 42 parts by weight of hydroxyethyl acrylate and 160 parts by weight of water into the reaction kettle, open the high-power industrial continuous flow poly-energy type ultrasonic disperser, and continuously ultrasonic for 2h, that is, 4A zeolite-olefin monomer dispersion liquid;

[0083] (2) Add 400 parts by weight of isopentenyl polyoxyethylene ether and 390 parts by weight of water into the reaction kettle, stir and dissolve at 35℃, and add 2.8 parts by weight of hydrogen peroxide;

[0084] (3) To the material obtained in step (2), solution one: 2.4 parts by weight of mercaptoethanol, 0.9 parts by weight of vitamin C, 160 parts by weight of water; Solution two: 4A zeolite-olefin monomer dispersion liquid obtained in (1) is added dropwise; After 3h, aging reaction is carried out at below 55℃ for 1h, and then neutralized with alkali to pH=6.2, to obtain the low sensitivity concrete slump retaining agent.

[0085] Comparative Example 5

[0086] A low sensitivity concrete slump retaining agent and its preparation method, which are made of the following raw material components by weight: isopentenyl polyoxyethylene ether 400 parts by weight, water 710 parts by weight, mercaptoethanol 2.4 parts by weight, acrylic acid 24 parts by weight, hydroxyethyl acrylate 42 parts by weight, hydrogen peroxide 2.8 parts by weight, vitamin C 0.9 parts by weight, 4A zeolite 7 parts by weight, and flake alkali 19 parts by weight.

[0087] The specific preparation method comprises the following steps:

[0088] (1) Take 2 parts by weight of 4A zeolite, 24 parts by weight of acrylic acid, 42 parts by weight of hydroxyethyl acrylate and 160 parts by weight of water into the reaction kettle, open the high-power industrial continuous flow poly-energy type ultrasonic disperser, and continuously ultrasonic for 2h, that is, 4A zeolite-olefin monomer dispersion liquid;

[0089] (2) Add 400 parts by weight of isopentenyl polyoxyethylene ether and 390 parts by weight of water into the reaction kettle, stir and dissolve at 35℃, and add 2.8 parts by weight of hydrogen peroxide;

[0090] (3) To the material obtained in step (2), solution one: 2.4 parts by weight of mercaptoethanol, 0.9 parts by weight of vitamin C, 160 parts by weight of water; Solution two: 4A zeolite-olefin monomer dispersion liquid obtained in (1) is added dropwise; After 3h, aging reaction is carried out at below 55℃ for 1h, and then neutralized with alkali to pH=6.2, to obtain the low sensitivity concrete slump retaining agent.

[0091] It should be noted that the specific parameters or some commonly used reagents in the above embodiments are specific embodiments or preferred embodiments under the concept of the present application, but not a limitation thereof; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present application.

[0092] The concrete slump keeping agents synthesized in Examples 1-7 and Comparative Examples 3-5, and commercially available polycarboxylic acid slump keeping agents of PSP-100 and KH-218 were subjected to comparative experiments, and after being compounded with S04-F water reducing agent at 1:1, Qingpeng P·O42.5R cement, machine-made sand with a clay content of 2.3% and a fineness modulus of 3.2, and continuous gradation gravel with a clay content of 0.6% and a nominal particle size of 5-10 mm and 10-20 mm were used as materials, and the dosage was 0.45% (converted solid dosage) based on the mass of cement, and the 2h time loss of concrete was tested according to the test method provided in GB8076-2008 "Concrete Admixture".

[0093] The concrete mix proportions for the test are shown in Table 1:

[0094] Table 1 Concrete component table

[0095] Raw materials Cement Machine-made sand Small stone Large stone Tap water Dosage / kg 320 780 300 815 165

[0096] The 3h time loss of each slump keeping agent was measured by test and shown in Table 2:

[0097] Table 2 Test results of examples and comparative examples

[0098]

[0099] From the test data in the above table, it can be seen that:

[0100] Under the same dosage conditions, compared with Comparative Example 1 and Comparative Example 2, after adding the slump keeping agent prepared in the present application, the influence of clay adsorption is small, the initial water reducing and slump keeping performance of the concrete is similar to that of the reference group, and the sensitivity is low, while the samples of the comparative examples are greatly affected by clay adsorption, and there is a significant reduction in the initial water reducing and slump keeping performance, which is not conducive to construction.

[0101] Compared with Comparative Example 3 and Example 5, using conventional zeolite instead of 4A zeolite will cause the time loss difference to occur, the conventional zeolite lacks the molecular sieve effect of 4A zeolite, the slump keeping agent macromolecule cannot synergize with the conventional zeolite, and the hydration reaction cannot be delayed and the dispersion performance cannot be improved, so the time loss is large.

[0102] Compared with Comparative Example 4 and Example 5, reducing the weight of 4A zeolite to less than 3.0-5.5 parts by weight will cause the time loss difference to occur, the amount of 4A zeolite is small, and the synergistic effect is weak, so the loss is large.

[0103] Compared with Example 5, if the weight of 4A zeolite is increased to more than 3.0-5.5 weight parts, the difference in the loss over time occurs, the amount of 4A zeolite is too much, the adsorption of the slump retaining agent polymer is too large, and the slump retaining agent cannot be effectively dispersed, so the loss is large.

[0104] It can be seen from the comparison of the above examples and the comparative examples that the sensitivity of the concrete slump retaining agent is reduced by using the 4A zeolite with a specific ratio in a specific system, which is suitable for the use in the southwest region of China and has important significance.

[0105] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A low-sensitivity concrete slump retainer, characterized in that: Based on weight parts, the composition includes 300-440 parts polyether monomer, 650-750 parts water, 1-6 parts chain transfer agent, 18-50 parts acrylic acid monomer, 28-60 parts olefinic ester monomer, 3-5.5 parts 4A zeolite, 1.8-5.6 parts initiator, 0.4-1.2 parts reducing agent, and 12-19 parts caustic soda flakes. The 4A zeolite, olefin monomers, olefin ester monomers, and water are ultrasonically dispersed in an ultrasonic disperser for 2-3 hours. This then forms a 4A zeolite-olefin monomer dispersion; The polyether monomer is at least one of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, or vinyl polyoxyethylene ether. The average molecular weight of the methyl allyl polyoxyethylene ether is 1964~3592, and its structural formula is: CH2=CH(CH3)CH2O(CH2CH2O)nH, where n=43~80; The isopentenyl polyoxyethylene ether has an average molecular weight of 1980~3608 and its structural formula is: (CH3)2C=CHCH2O(CH2CH2O)nH, where n=43~80; The vinyl polyoxyethylene ether has an average molecular weight of 1893~3653 and its structural formula is: C6H 12 O3(CH2CH2O)nH, where n=40~80; The pH of low-sensitivity concrete slump retainer is 5.8~6.

8.

2. The low-sensitivity concrete slump retainer according to claim 1, characterized in that: The chain transfer agent is one or more of the following: isopropanol, phosphorous acid and hypophosphite and their salts, sulfurous acid, bisulfite, dithionite and metabisulfite and their salts, mercaptoethanol, mercaptoglycerol, mercaptoacetic acid, mercaptopropionic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, 2-mercaptoethanesulfonic acid and their salts.

3. The low-sensitivity concrete slump retainer according to claim 1, characterized in that: The initiator is one or a combination of hydrogen peroxide, potassium persulfate or sodium persulfate, ammonium persulfate, and azobisisobutyronitrile.

4. The low-sensitivity concrete slump retainer according to claim 1, characterized in that: The reducing agent is one or more of the following: vitamin C, oxalic acid, ferrous sulfate, cuprous sulfate, oxalic acid, sodium bisulfite, sodium sulfite, glucose, fructose, ethylenediamine, diphenylamine, sodium monohydrogen phosphate, or potassium monohydrogen phosphate.

5. The preparation method of the low-sensitivity concrete slump retainer according to claim 4, characterized in that: The olefinic monomers are acrylic acid, crotonic acid, citraconic acid, maleic acid, methacrylic acid, itaconic acid, fumaric acid, and at least one of monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts, or their anhydrides; The ester monomer is at least one of methyl acrylate, ethyl acrylate, and hydroxypropyl acrylate.

6. A method for preparing a low-sensitivity concrete slump retainer according to any one of claims 1-5, characterized in that, Includes the following steps: Take 3-5.5 parts by weight of 4A zeolite, 18-50 parts by weight of olefinic monomers, 28-60 parts by weight of olefinic ester monomers, and 140-170 parts by weight of water and add them to the reaction vessel. Turn on the high-power industrial-grade continuous flow energy-concentrating ultrasonic disperser and continue to sonicate for 2-3 hours to obtain 4A zeolite-olefinic monomer dispersion. Add 300-440 parts by weight of polyether monomer and 300-400 parts by weight of water to a reactor, stir and mix at 15-45°C to dissolve, and add 1.8-5.6 parts by weight of initiator; the above polyether monomer is methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether or vinyl polyoxyethylene ether to obtain mixture A. Solution 1: 1-6 parts by weight of chain transfer agent, 0.4-1.2 parts by weight of reducing agent, and 160-180 parts by weight of water were added dropwise in sequence; Solution 2: the obtained 4A zeolite-olefin monomer dispersion; After adding the agent dropwise for 1 to 3.5 hours, the mixture is kept at a temperature below 55°C for 1 to 2 hours to carry out an aging reaction. Then, it is neutralized with an alkaline solution to a pH of 5.8 to 6.8 to obtain the concrete slump retainer.

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