A concrete admixture sensitive inhibitor, preparation method and application

Abstract

The present invention relates to a concrete admixture sensitive inhibitor, a preparation method and an application. The concrete admixture sensitive inhibitor comprises: polyethylene glycol, polyethylene glycol monomethyl ether, acrylic acid, a small molecule monoacid, an inhibitor, a catalyst, a molecular regulator, an initiator and a reducing agent. The preparation method is to use monomers with different molecular weights to prepare a polymer with a wide molecular weight distribution through a special synthesis process, and to use the combination of macromolecules and small molecules to reduce the sensitivity of polycarboxylic acid water reducers. The concrete admixture sensitive inhibitor prepared by the present invention can be directly compounded with a polycarboxylic acid water reducer, or directly added when the concrete is sensitive. The concrete admixture sensitive inhibitor prepared by the present invention can reduce the sensitivity of various factors such as water reducer dosage, type, water consumption, temperature and raw materials.

Description

Technical Field

[0001] The invention belongs to the field of concrete admixtures, and in particular relates to a concrete admixture sensitive inhibitor, a preparation method and an application thereof. Background Art

[0002] In recent years, under the background of the great wave of infrastructure construction in my country, polycarboxylic acid admixtures have become the most widely used water reducer in the field of engineering and construction due to their low dosage, excellent dispersibility, functional designability, green environmental protection and other advantages. However, as its application becomes wider and wider, the requirements for concrete in actual projects are getting higher and higher, as well as the complexity and variability of concrete raw materials, environmental differences, limitations of technical personnel's understanding, and usage habits, many problems have arisen in the process of using polycarboxylic acid water reducers, which directly affect the application effect of polycarboxylic acid water reducers.

[0003] The variety of concrete raw materials is complex across the country, and the production process is also affected by factors such as fluctuations in the moisture content of sand and gravel, temperature changes, and fluctuations in the dosage. The problem of polycarboxylic acid water reducers being sensitive to concrete is becoming more and more prominent. This is mainly manifested in the fact that when polycarboxylic acid water reducers are directly applied to concrete, they often have sensitivity problems such as poor adaptability to cement and mineral admixtures, unstable concrete working performance, easy segregation, or large slump loss, which makes it impossible to meet the requirements of the construction site; in order to pursue cost-effectiveness, most polycarboxylic acid admixtures currently have a high water reduction rate, good slump retention, and excellent concrete rheological properties, but the dosage is sensitive; in order to meet the requirements of slump retention in long-distance transportation of concrete, a large amount of slump retaining agent is often added during the admixture compounding process, which easily leads to the disadvantage of delayed concrete reaction. These have greatly restricted the promotion and use of polycarboxylic acid water reducers.

[0004] In order to reduce the sensitivity of concrete to ambient temperature, water consumption per cubic meter, water reducer dosage, cement type and machine-made sand dosage, researchers have developed a number of low-sensitive polycarboxylate water reducers.

[0005] CN109312032B discloses a method for preparing a low-sensitivity polycarboxylic acid at low temperature, wherein a precursor is prepared by free radical polymerization of unsaturated ester macromonomers and unsaturated monomer derivatives under irradiation by a photoinitiator, and then the precursor is polymerized with unsaturated ether macromonomers, unsaturated monomer derivatives, etc. by aqueous solution to obtain a product. CN106432628B discloses a low-sensitivity anti-mud ether-ester copolymer polycarboxylic acid water reducer and its preparation method, which is polymerized by 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 2000 to 5000, methoxy polyethylene glycol methacrylate, unsaturated monocarboxylic acid, unsaturated carboxylic acid ester monomers, dibutyl itaconate, and unsaturated amphoteric quaternary phosphonium salt. CN112707667B discloses a low-sensitivity water reducer and a preparation method thereof, comprising EPEG, unsaturated carboxylic acid small monomers, oxidants, reducing agents, molecular weight regulators and layered calcium aluminum double hydroxide components modified by silane coupling agents, cross-linking CaAl-LDH nanosheets with a large amount of positive charge with low-sensitivity polycarboxylic acids, reducing the sensitivity of polycarboxylic acids to changes in mud content. CN108559034 discloses an ether-based low-sensitivity polycarboxylic acid water reducer and a preparation method thereof, wherein the side chains are two-end double-stage polyether structures connected by ester groups, which significantly reduces the sensitivity of the product.

[0006] Researchers have almost focused on preparing low-sensitivity polycarboxylate water-reducing agents by modifying or modifying the polycarboxylate water-reducing agent molecular chain to solve the sensitivity problem of polycarboxylate water-reducing agents. However, functional modification is bound to have a certain negative impact or inhibitory effect on the water-reducing and slump-retaining properties of polycarboxylate water-reducing agents.

[0007] The applicant's previous applications CN110885389B, a concrete viscosity reducer synthesized by a simple method and its preparation method, and CN202011643536.7, a multifunctional concrete water-retaining agent and its preparation method, both pointed out that the combination of macromolecules and small molecules can improve the water retention of concrete and reduce the sensitivity of water reducers. In the previous applications, the applicant used static reaction and one-pot feeding methods to control the molecular weight and molecular weight distribution. Although this method can obtain polymers with a wide molecular weight distribution, it cannot achieve precise control. Summary of the invention

[0008] In view of the deficiencies in the above-mentioned prior art, the inventors conducted further design and research and provided a concrete admixture sensitive inhibitor, a preparation method and an application thereof.

[0009] A concrete admixture sensitive inhibitor comprises polyethylene glycol, polyethylene glycol monomethyl ether, acrylic acid, small molecule monoacid, polymerization inhibitor, catalyst, molecular regulator, initiator and reducing agent. The molar ratio of polyethylene glycol, polyethylene glycol monomethyl ether, acrylic acid, small molecule monoacid, polymerization inhibitor, catalyst, molecular regulator, initiator and reducing agent is 0.12-0.3: 0.8-1.6: 2-6: 0.19-0.48: 0.001-0.004: 0.5-1.4: 0.5-1.2: 0.1-0.5: 0.1-0.4.

[0010] Preferably, the polyethylene glycol includes PEG2000, PEG3000, PEG4000, PEG6000, PEG8000, and PEG10000, and the molar ratio of PEG2000:PEG3000:PEG4000:PEG6000:PEG8000:PEG10000=1:1:1:1:1:1.

[0011] Preferably, the polyethylene glycol monomethyl ether includes MPEG200, MPEG350, MPEG400, MPEG500, MPEG750, MPEG1000, MPEG1200, and MPEG1500, and the molar ratio of MPEG200:MPEG350:MPEG400:MPEG500:MPEG750:MPEG1000:MPEG1200:MPEG1500=1:1:1:1:1:1:1:1:1.

[0012] Preferably, the small molecule monoacid includes formic acid, acetic acid, propionic acid, benzoic acid, and n-octanoic acid; the molar ratio of formic acid, acetic acid, propionic acid, benzoic acid, and n-octanoic acid is 1:1:1:1:1.

[0013] Preferably, the inhibitor is ZJ-705, and the catalyst is one of aminosulfonic acid, p-toluenesulfonic acid, and strongly acidic cation exchange resin 732 type.

[0014] Preferably, the molecular regulator is one or more of mercaptoethanol, thioglycolic acid, dodecyl mercaptan, mercaptopropionic acid, mercaptopropanol, sodium formate, and sodium hypophosphite; the initiator includes one or more of ammonium persulfate, potassium persulfate, 30% hydrogen peroxide, and 30% tert-butyl hydroperoxide; the reducing agent includes one or more of bleaching agent, L-sodium ascorbate, sodium pyrosulfite, E51, and ferrous sulfate.

[0015] A method for preparing a concrete admixture sensitive inhibitor comprises the following steps:

[0016] S1. Add PEG2000, PEG3000, PEG4000, PEG6000, PEG8000 and PEG10000 into the reactor at a molar ratio of PEG2000:PEG3000:PEG4000:PEG6000:PEG8000:PEG10000=1:1:1:1:1:1, start stirring, add inhibitor and catalyst in sequence, and then add acrylic acid, wherein the molar ratio of PEG to acrylic acid is 1:1.1-1.6; raise the temperature to 80-90°C and react for 4-6 hours.

[0017] S2. Divide the above product into 5 equal parts by weight, react with small molecule monoacid at 80-90°C for 4-6 hours, and cool to room temperature, wherein the molar ratio of PEG to small molecule monoacid is 1:0.22-0.32.

[0018] S3. Add MPEG200, MPEG350, MPEG400, MPEG500, MPEG750, MPEG1000, MPEG1200 and MPEG1500 in a molar ratio of MPEG200:MPEG350:MPEG400:MPEG500:MPEG750:MPEG1000:MPEG1200:MPEG1500=1:1:1:1:1:1:1 into a reactor, start stirring, add inhibitor and catalyst in sequence, and then add acrylic acid, wherein the molar ratio of PEG to acrylic acid is 1:1.1-1.6; heat to 80-90℃ for reaction for 6-8h, and cool to room temperature;

[0019] S4. Dissolving the remaining acrylic acid and the reducing agent in deionized water to prepare a solution A;

[0020] S5. The initiator is dissolved in deionized water to prepare solution B;

[0021] S6. At room temperature, 1 / 3 of the product of S1, 1 / 3 of the product of S2, and a chain transfer agent were dissolved in deionized water to prepare a C solution; 1 / 3 of the A solution and 1 / 3 of the B solution were added dropwise to the stirred C solution, the A solution was added for 45 minutes, and the B solution was added for 60 minutes; after the end, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 were added to the solution C, 1 / 3 of the A solution and 1 / 3 of the B solution were added dropwise to the stirred C solution, and the A solution was added for 45 minutes and the B solution was added for 60 minutes. The time for adding liquid A dropwise is 45 minutes, and the time for adding liquid B dropwise is 60 minutes; then, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 are continuously added into solution C, and the temperature is raised to 60-70°C. 1 / 3 of solution A and 1 / 3 of solution B are respectively added dropwise into the stirred solution C, and the time for adding liquid A dropwise is 60 minutes, and the time for adding liquid B dropwise is 90 minutes; after the addition is completed, the stirring is continued for 1 hour to obtain a concrete admixture sensitive inhibitor with a solid content of 35-38%.

[0022] The mass concentration of the configured A solution is 10~15%, and the mass concentration of the B solution is 8~10%.

[0023] The concrete admixture sensitivity inhibitor prepared by the present invention can be directly compounded with polycarboxylic acid water reducer, with a dosage of 10-20 kg / ton (1.6% dosage); it can also be directly added when concrete becomes sensitive, with 0.5-1 kg added to 1 cubic meter of concrete.

[0024] Mechanism of the present invention: In previous studies, the present inventors used static reaction and one-time feeding to obtain a polymer with a wide molecular weight distribution, which can be increased by 20% to 50% of the base dosage, although there is segregation, but no grip, good softness, and can still meet the pumping requirements. Based on such theories and facts, the present invention aims to design a polymer with a wide molecular weight distribution to reduce the sensitivity of concrete to ambient temperature, water consumption per cubic meter, water reducer dosage, cement type and machine-made sand dosage.

[0025] Although static reaction and one-time feeding can increase the molecular weight dispersion, the entire reaction is greatly affected by temperature, reaction environment size, static time, stirring node, and raw material quality fluctuations. The entire reaction conditions need to be repeatedly explored and verified, and there is a risk of performance stability.

[0026] The present application utilizes monomers with different molecular weights to prepare polymers with a wide molecular weight distribution through a special synthesis process, and utilizes the combination of macromolecules and small molecules to reduce the sensitivity of polycarboxylate water reducers.

[0027] The present invention utilizes polyethylene glycol monomethyl ether (MPEG) with a molecular weight of 200-1500 to esterify with acrylic acid to form active double bond molecules, which are evenly or in a certain amount distributed in different molecular weight ranges (100-500, 500-1000, 1000-2000, etc.); utilizes polyethylene glycol (PEG) with a molecular weight of 2000-10000 to esterify with acrylic acid to form active double bond molecules, which are evenly or in a certain amount distributed in different molecular weight ranges (2000-3000, 3000-4000, 4000-5000, 5000-6000, 6000-8000, 8000-10000, etc.); and simultaneously utilizes acids with different molecular weights to perform end-capping esterification on the other side (formic acid, acetic acid, propionic acid, benzoic acid, n-octanoic acid), thereby improving the hydrophilicity of the monomers and the differentiation of molecular weights.

[0028] In preparation method S5, the base material is added three times, the redox agent is added dropwise, and the chain transfer agent is added once, so that the polymers in the whole system also form molecular weight differences. The chain transfer agent is added to the base material once, and there is too much chain transfer agent in the early stage, and the molecular weight distribution formed by polymerization is relatively uniform, and the molecular weight is small (500-5000); in the middle stage, the chain transfer agent is gradually consumed, and the molecular weight of the polymer increases (5000-20000); in the later stage, the chain transfer agent is almost consumed, and the polymer molecular chain length increases more rapidly. At the same time, a small number of small molecular weight polymers will also be activated to participate in the polymerization, thus forming polymers with uneven side chain lengths and a certain amount of main chain molecular weight distribution in different molecular weight ranges.

[0029] The dispersing effect of polycarboxylic acid water-reducing agent is mainly to disperse cement particles by utilizing its steric hindrance effect and electrostatic repulsion effect. The neat molecular weight distribution and the existence of large molecular weight ensure the excellent performance of polycarboxylic acid water-reducing agent. However, the source of this advantage is the adsorption of cement by the polycarboxylic acid water-reducing agent molecular chain. Once the external environment changes (ambient temperature, water consumption, water-reducing agent dosage, cement and admixture types and sand ratio), the adsorption of polycarboxylic acid molecular chain will change accordingly. Once the polycarboxylic acid molecular chain cannot quickly adapt to this change, it will show sensitivity.

[0030] The concrete admixture sensitive inhibitor prepared by the present invention can make up for the molecular weight distribution defects of polycarboxylate water reducer. The small molecular weight polymer in the concrete admixture sensitive inhibitor can be quickly adsorbed on the surface of cement particles in the early stage of cement dispersion due to its small molecular weight and high degree of freedom; the large molecular weight polymer has a large steric hindrance due to its large molecular weight and stronger dispersion effect; the combination of large molecules and small molecules forms continuous adsorption. For sudden changes in materials and environment, polymers of different molecular weights can coordinate their adsorption effects with each other to form a stable and continuous release state, thereby reducing the sensitivity of the water reducer.

[0031] The beneficial effects of the present invention are:

[0032] The concrete admixture sensitivity inhibitor prepared by the present invention can reduce the sensitivity of various factors such as water reducing agent dosage, type, water consumption, temperature and raw materials.

[0033] Specific implementation examples

[0034] The technical solution of the present invention is further described and explained below through specific embodiments.

[0035] Example 1

[0036] 0.005mol PEG2000, 0.005mol PEG3000, 0.005mol PEG4000, 0.005mol PEG6000, 0.005mol PEG8000 and 0.005mol PEG10000 were put into the reactor, stirring was started, 0.0001mol ZJ-705 and 0.07mol aminosulfonic acid were added in sequence, and then 0.033mol acrylic acid was added. The temperature was raised to 80°C and reacted for 6h. Then, the mixture was divided into 5 parts by weight and reacted with 0.0066mol formic acid, 0.0066mol acetic acid, 0.0066mol propionic acid, 0.0066mol benzoic acid and 0.0066mol n-octanoic acid respectively at 80°C for 6 hours, and then cooled to room temperature.

[0037] 0.02mol MPEG200, 0.02mol MPEG350, 0.02mol MPEG400, 0.02mol MPEG500, 0.02mol MPEG750, 0.02mol MPEG1000, 0.02mol MPEG1200 and 0.02mol MPEG1500 were put into a reactor, stirring was started, 0.0002 ZJ-705 and 0.054mol aminosulfonic acid were added in sequence, followed by 0.176mol acrylic acid, the temperature was raised to 90°C for reaction for 6h, and then cooled to room temperature.

[0038] Dissolve 0.2 mol of acrylic acid and 0.01 mol of bleaching powder in 90 g of deionized water to prepare solution A;

[0039] Dissolve the 0.03 mol of ammonium persulfate in 62 g of deionized water to prepare solution B;

[0040] At room temperature, 1 / 3 of the mass of the product of S1, 1 / 3 of the mass of the product of S2, and 0.1 mol of mercaptoethanol were dissolved in 477g of deionized water to prepare solution C. 1 / 3 of solution A and 1 / 3 of solution B were added dropwise to the stirred solution C, and the time for adding solution A was 45min, and the time for adding solution B was 60min. After the end, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 were added to solution C, and 1 / 3 of solution A and 1 / 3 of solution B were added dropwise to the stirred solution C, and the time for adding solution A was 45min, and the time for adding solution B was 60min. After that, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 were continued to be added to solution C, and the temperature was raised to 60°C, and 1 / 3 of solution A and 1 / 3 of solution B were added dropwise to the stirred solution C, and the time for adding solution A was 60min, and the time for adding solution B was 90min. After the addition is completed, continue to keep warm and stir for 1 hour to obtain the concrete admixture sensitive inhibitor.

[0041] Example 2

[0042] 0.005mol PEG2000, 0.005mol PEG3000, 0.005mol PEG4000, 0.005mol PEG6000, 0.005mol PEG8000 and 0.005mol PEG10000 were put into the reactor, stirring was started, 0.0002mol ZJ-705 and 0.04mol p-toluenesulfonic acid were added in sequence, and then 0.048mol acrylic acid was added. The temperature was raised to 90°C and reacted for 6h. Then, the mixture was divided into 5 parts by weight and reacted with 0.007mol formic acid, 0.007mol acetic acid, 0.007mol propionic acid, 0.007mol benzoic acid and 0.007mol n-octanoic acid respectively at 90°C for 6 hours, and then cooled to room temperature.

[0043] 0.02mol MPEG200, 0.02mol MPEG350, 0.02mol MPEG400, 0.02mol MPEG500, 0.02mol MPEG750, 0.02mol MPEG1000, 0.02mol MPEG1200 and 0.02mol MPEG1500 were put into a reactor, stirring was started, 0.0002 ZJ-705 and 0.056mol aminosulfonic acid were added in sequence, followed by 0.25mol acrylic acid, the temperature was raised to 80°C for reaction for 8h, and then cooled to room temperature.

[0044] 0.3 mol of acrylic acid, 0.015 mol of sodium L-ascorbate, and 0.005 mol of ferrous sulfate were dissolved in 144 g of deionized water to prepare solution A;

[0045] Dissolve the 0.02 mol potassium persulfate in 53 g of deionized water to prepare solution B;

[0046] At room temperature, 1 / 3 of the mass of the product of S1, 1 / 3 of the mass of the product of S2, 0.05 mol of thioglycolic acid, and 0.05 mol of mercaptopropanol were dissolved in 442 g of deionized water to prepare solution C. 1 / 3 of solution A and 1 / 3 of solution B were added dropwise to the stirred solution C, and the time for adding solution A was 45 minutes, and the time for adding solution B was 60 minutes. After the end, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 were added to solution C, and 1 / 3 of solution A and 1 / 3 of solution B were added dropwise to the stirred solution C, and the time for adding solution A was 45 minutes, and the time for adding solution B was 60 minutes. After that, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 were added to solution C, and the temperature was raised to 60°C. 1 / 3 of solution A and 1 / 3 of solution B were added dropwise to the stirred solution C, and the time for adding solution A was 60 minutes, and the time for adding solution B was 90 minutes. After the addition was completed, the mixture was kept warm and stirred for 1 hour to obtain the concrete admixture sensitive inhibitor.

[0047] Example 3

[0048] 0.005mol PEG2000, 0.005mol PEG3000, 0.005mol PEG4000, 0.005mol PEG6000, 0.005mol PEG8000 and 0.005mol PEG10000 were put into the reactor, stirring was started, 0.0003mol ZJ-705 and 0.04mol p-toluenesulfonic acid were added in sequence, and then 0.036mol acrylic acid was added. The temperature was raised to 90°C and reacted for 6h. Then, the mixture was divided into 5 parts by weight and reacted with 0.0096mol formic acid, 0.0096mol acetic acid, 0.0096mol propionic acid, 0.0096mol benzoic acid and 0.0096mol n-octanoic acid at 90°C for 6 hours, and then cooled to room temperature.

[0049] 0.01mol MPEG200, 0.01mol MPEG350, 0.01mol MPEG400, 0.01mol MPEG500, 0.01mol MPEG750, 0.01mol MPEG1000, 0.01mol MPEG1200 and 0.01mol MPEG1500 were put into a reactor, stirring was started, 0.0001 ZJ-705 and 0.1mol strong acid cation exchange resin 732 were put into the reactor in turn, and then 0.01mol acrylic acid was put into the reactor, the temperature was raised to 90°C for reaction for 8h, the mixture was cooled to room temperature and the catalyst was filtered out.

[0050] 0.4 mol of acrylic acid and 0.04 mol of sodium pyrosulfite were dissolved in 196 g of deionized water to prepare solution A;

[0051] Dissolve the 0.05 mol hydrogen peroxide (30%) in 65 g deionized water to prepare solution B;

[0052] At room temperature, 1 / 3 of the mass of the product of S1, 1 / 3 of the mass of the product of S2, and 0.05 mol of dodecyl mercaptan are dissolved in 275g of deionized water to prepare solution C. 1 / 3 of solution A and 1 / 3 of solution B are added dropwise to the stirred solution C, and the time for adding solution A is 45min, and the time for adding solution B is 60min. After the end, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 are added to solution C, and 1 / 3 of solution A and 1 / 3 of solution B are added dropwise to the stirred solution C, and the time for adding solution A is 45min, and the time for adding solution B is 60min. After that, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 are continued to be added to solution C, and the temperature is raised to 60°C, and 1 / 3 of solution A and 1 / 3 of solution B are added dropwise to the stirred solution C, and the time for adding solution A is 60min, and the time for adding solution B is 90min. After the addition is completed, continue to keep warm and stir for 1 hour to obtain the concrete admixture sensitive inhibitor.

[0053] Example 4

[0054] 0.002mol PEG2000, 0.002mol PEG3000, 0.002mol PEG4000, 0.002mol PEG6000, 0.002mol PEG8000 and 0.002mol PEG10000 were put into the reactor, stirring was started, 0.0001mol ZJ-705 and 0.015mol p-toluenesulfonic acid were added in sequence, followed by 0.015mol acrylic acid, the temperature was raised to 90°C and reacted for 8h, then the mixture was divided into 5 parts by weight and reacted with 0.0038mol formic acid, 0.0038mol acetic acid, 0.0038mol propionic acid, 0.0038mol benzoic acid and 0.0038mol n-octanoic acid at 90°C for 8 hours, and then cooled to room temperature.

[0055] 0.01mol MPEG200, 0.01mol MPEG350, 0.01mol MPEG400, 0.01mol MPEG500, 0.01mol MPEG750, 0.01mol MPEG1000, 0.01mol MPEG1200 and 0.01mol MPEG1500 were put into a reactor, stirring was started, 0.0001mol ZJ-705 and 0.035mol aminosulfonic acid were added in sequence, and then 0.088mol acrylic acid was added. The temperature was raised to 90°C for reaction for 8h, and then cooled to room temperature and the catalyst was filtered out.

[0056] Dissolve 0.1 mol of acrylic acid and 0.02 mol of E51 in 96 g of deionized water to prepare solution A;

[0057] Dissolve the 0.01 mol of tert-butyl hydroperoxide (30%) in 27 g of deionized water to prepare solution B;

[0058] At room temperature, 1 / 3 of the mass of the product of S1, 1 / 3 of the mass of the product of S2, and 0.12 mol of sodium hypophosphite are dissolved in 182 g of deionized water to prepare solution C. 1 / 3 of solution A and 1 / 3 of solution B are added dropwise to the stirred solution C, and the time for adding solution A is 45 minutes, and the time for adding solution B is 60 minutes. After the end, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 are added to solution C, and 1 / 3 of solution A and 1 / 3 of solution B are added dropwise to the stirred solution C, and the time for adding solution A is 45 minutes, and the time for adding solution B is 60 minutes. After that, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 are continued to be added to solution C, and the temperature is raised to 60°C, and 1 / 3 of solution A and 1 / 3 of solution B are added dropwise to the stirred solution C, and the time for adding solution A is 60 minutes, and the time for adding solution B is 90 minutes. After the addition is completed, continue to keep warm and stir for 1 hour to obtain the concrete admixture sensitive inhibitor.

[0059] Test the sensitivity of concrete admixture sensitive inhibitor to various factors such as water reducing agent dosage, water consumption, temperature and raw materials. The specific test method is as follows:

[0060] Table 1 Concrete mix ratio

[0061]

[0062] (1) Evaluation of dosage sensitivity

[0063] The sensitivity was evaluated by adjusting the admixture dosage while keeping the concrete mix ratio unchanged. In order to compare the performance, three different types of polycarboxylate water reducers were used for verification, namely JS-1, JS-2, and JS-3.

[0064] Table 2 Expansion of concrete at different dosages

[0065]

[0066] From the data in Table 2, it can be seen that the expansion of the purchased JS-1, JS-2, and JS-3 water reducers is more than 620mm when the dosage is 1.8%; when the dosage is 2.0%, the expansion is more than 670, and serious water bleeding and segregation occur. When 15 kg of Example 1 to Example 4 are compounded in the JS-1 water reducer, it can be clearly seen that at low dosages, when the water reducer is unsaturated (expansion is less than 580mm), the addition of Example 1 to Example 4 has the function of assisting water reduction and promoting the dispersion of cement; at high dosages, the use of Example 1 to Example 4 can increase the dosage width of the water reducer. When the dosage is increased by 4 (1.8%-2.2%), the expansion of the concrete does not change much, reducing the sensitivity of the water reducer dosage change.

[0067] (2) Water consumption sensitivity assessment

[0068] Keeping the admixture dosage at 1.6% and the concrete mix ratio unchanged, adjust the water consumption of the concrete mix ratio and increase the unit water consumption by 15 kg. Calculate the difference in concrete expansion under the two water consumptions. The smaller the difference, the less sensitive it is to the water consumption.

[0069] Table 3 Expansion and difference in concrete with different water content

[0070]

[0071] It can be seen from Table 3 that the difference in concrete expansion of the purchased JS-1, JS-2, and JS-3 water reducers is not much different under the condition of increasing unit water consumption, and the sensitivity difference is not much; when 15 kg of Example 1 to Example 4 are compounded in the JS-1 water reducer, it can be clearly seen that the difference in expansion of Example 1 to Example 4 is lower than that of JS-1, JS-2, and JS-3 water reducers.

[0072] (3) Raw material sensitivity evaluation

[0073] Keeping the admixture dosage at 1.6% and the concrete mix ratio unchanged, replace factors such as cement and sand, and conduct tests according to the test method for dosage sensitivity evaluation. Test the expansion corresponding to the raw materials that are not replaced and the raw materials that are replaced. According to raw material sensitivity = expansion value when the raw materials are replaced - expansion value when the raw materials are not replaced, calculate the absolute value of the difference between the expansion value when the raw materials are replaced and the expansion value when the raw materials are not replaced. The smaller the value, the less sensitive it is to the raw materials.

[0074] Table 4 Expansion and difference in different types of sand

[0075]

[0076] It can be seen from Table 4 that the initial expansion of the purchased JS-1 water reducer for concrete using different types of sand is different. The expansion of the concrete using river sand is smaller than that using machine-made sand. This is because the proportion and difference of river sand are poor. The poor adaptability of JS-1 water reducer to river sand leads to poor water retention and slurry extraction performance of river sand, resulting in small expansion and water seepage. By compounding 15 kg of Example 1 to Example 4 in the JS-1 water reducer, it can be clearly seen that the expansion difference is smaller than that of the single JS-1 water reducer, and the expansion of the concrete using river sand is larger than that using machine-made sand. This may also be because the concrete admixture sensitive inhibitor prepared by the present invention improves the water retention performance of concrete through its molecular weight adjustment, grading adjustment, and system homogeneity.

[0077] (4) Evaluation of compound dosage

[0078] Table 5 Compounding methods of admixtures

[0079]

[0080] It can be seen from the data in Table 5 that the concrete admixture sensitive inhibitor prepared by the present invention can be directly compounded with the polycarboxylic acid water reducer, and the dosage is 10-20 kg / ton (1.6% dosage). When the dosage of Example 1 is 5 kg, the dosage is increased from 1.6% to 1.8%, and the expansion is increased by 50 mm; when the dosage of Example 1 is 10-20 kg, the dosage is increased from 1.6% to 1.8%, and the expansion is increased by about 10 mm, and the loss of concrete over time is not affected; when the dosage of Example 1 is 25 kg, the dosage is increased from 1.6% to 1.8%, and the expansion is reduced by 40 mm, which shows that the concrete admixture sensitive inhibitor prepared by the present invention will produce side effects after the dosage is too high, which has an adverse effect on the performance of the polycarboxylic acid water reducer.

[0081] (5) Direct addition

[0082] Table 6 Direct addition amount

[0083]

[0084] From the data in Table 6, it can be seen that when the concrete is sensitive, it should be added directly, 0.5-1kg per cubic meter of concrete. If the dosage is too low, the inhibitory effect on sensitivity is not obvious, and if the dosage is too high, side effects will occur and the performance of the polycarboxylate water reducer will be adversely affected.

Claims

1. A concrete admixture sensitive inhibitor, characterized in that include: Polyethylene glycol, polyethylene glycol monomethyl ether, acrylic acid, small molecule monoacid, inhibitor, catalyst, molecular weight regulator, initiator, reducing agent; the molar ratio of polyethylene glycol, polyethylene glycol monomethyl ether, acrylic acid, small molecule monoacid, inhibitor, catalyst, molecular weight regulator, initiator, reducing agent is 0.12-0.3: 0.8-1.6: 2-6: 0.19-0.48: 0.001-0.004: 0.5-1.4: 0.5-1.2: 0.1-0 .5:0.1~0.4; the polyethylene glycol includes: polyethylene glycol with an average molecular weight of 2000, polyethylene glycol with an average molecular weight of 3000, polyethylene glycol with an average molecular weight of 4000, polyethylene glycol with an average molecular weight of 6000, polyethylene glycol with an average molecular weight of 8000, and polyethylene glycol with an average molecular weight of 10000; the molar ratio of PEG2000:PEG3000:PEG4000:PEG6000:PEG8000:PE G10000 is 1:1:1:1:1:1:1; the polyethylene glycol monomethyl ether includes: polyethylene glycol monomethyl ether with an average molecular weight of 200, polyethylene glycol monomethyl ether with an average molecular weight of 350, polyethylene glycol monomethyl ether with an average molecular weight of 400, polyethylene glycol monomethyl ether with an average molecular weight of 500, polyethylene glycol monomethyl ether with an average molecular weight of 750, polyethylene glycol monomethyl ether with an average molecular weight of 1000, polyethylene glycol monomethyl ether with an average molecular weight of 1200, and polyethylene glycol monomethyl ether with an average molecular weight of 1500. The amount of polyethylene glycol monomethyl ether is 1500; the molar ratio of MPEG200:MPEG350:MPEG400:MPEG500:MPEG750:MPEG1000:MPEG1200:MPEG1500 is 1:1:1:1:1:1:1:1:1; the small molecule monobasic acid includes: formic acid, acetic acid, propionic acid, benzoic acid, and n-octanoic acid, and the molar ratio of formic acid: acetic acid: propionic acid: benzoic acid: n-octanoic acid is 1:1:1:1:

1.

2. The concrete admixture sensitive inhibitor according to claim 1, characterized in that: The inhibitor is tetramethyl piperidine nitroxide free radical phosphite triester ZJ-705; the catalyst is one of aminosulfonic acid, p-toluenesulfonic acid, and strongly acidic cation exchange resin 732; the molecular weight regulator is one or more of mercaptoethanol, thioglycolic acid, dodecyl mercaptan, mercaptopropionic acid, mercaptopropanol, sodium formate, and sodium hypophosphite; the initiator includes one or more of ammonium persulfate, potassium persulfate, 30% hydrogen peroxide, and 30% tert-butyl hydroperoxide; the reducing agent includes one or more of bleaching agent, L-sodium ascorbate, sodium pyrosulfite, E51, and ferrous sulfate.

3. A method for preparing a concrete admixture sensitive inhibitor as claimed in claim 1, characterized in that The following steps are involved: S1. PEG2000, PEG3000, PEG4000, PEG6000, PEG8000 and PEG10000 are added into a reactor at a molar ratio of PEG2000:PEG3000:PEG4000:PEG6000:PEG8000:PEG10000=1:1:1:1:1:1, stirring is started, inhibitor and catalyst are added in sequence, and then acrylic acid is added, wherein the molar ratio of PEG to acrylic acid is 1:1.1-1.6; the temperature is raised to 80-90°C and the reaction is carried out for 4-6 hours; the above product is divided into 5 parts by weight, and the parts are reacted with small molecule monoacids at 80-90°C for 4-6 hours, and then cooled to room temperature, wherein the molar ratio of PEG to small molecule monoacids is 1:0.22-0.32; S2. The molar ratio of MPEG200, MPEG350, MPEG400, MPEG500, MPEG750, MPEG1000, MPEG1200, and MPEG1500 is as follows: 1:1:1:1:1:1:1 put into the reaction kettle, start stirring, add inhibitor and catalyst in sequence, and then add acrylic acid, wherein the molar ratio of MPEG to acrylic acid is 1:1.1-1.6; heat to 80-90℃, react for 6-8h, and cool to room temperature; S3. The remaining acrylic acid and the reducing agent are dissolved in deionized water to prepare a solution A; S4. The initiator is dissolved in deionized water to prepare solution B; S5. At room temperature, 1 / 3 of the product of S1, 1 / 3 of the product of S2, and a molecular weight regulator are dissolved in deionized water to prepare a C solution; 1 / 3 of the A solution and 1 / 3 of the B solution are respectively added dropwise to the stirred C solution, and the A solution is added for 45 minutes and the B solution is added for 60 minutes; after the end, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 are added to the C solution, 1 / 3 of the A solution and 1 / 3 of the B solution are respectively added dropwise to the stirred C solution, and the A solution is added for 45 minutes and the B solution is added for 60 minutes. The solution was added dropwise for 45 minutes, and the solution B was added dropwise for 60 minutes. After that, 1 / 3 of the product of S1 and 1 / 3 of the product of S2 were added to the solution C. The temperature was raised to 60-70°C, and 1 / 3 of the solution A and 1 / 3 of the solution B were added dropwise to the stirred solution C. The solution A was added dropwise for 60 minutes, and the solution B was added dropwise for 90 minutes. After the addition was completed, the mixture was kept warm and stirred for 1 hour to obtain a concrete admixture sensitive inhibitor with a solid content of 35-38%.

4. An application of the concrete admixture sensitive inhibitor as claimed in claim 1, characterized in that: When concrete becomes sensitive, add concrete admixture sensitive inhibitor directly, adding 0.5-1kg to 1 cubic meter of concrete.

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