A phosphate-based water reducer specially used for highly robust self-compacting concrete and a preparation method thereof

Abstract

The invention provides a phosphoric acid-based water reducer specially used for self-compacting concrete with high robustness and a preparation method thereof. The phosphoric acid-based water reducer specially used for self-compacting concrete with high robustness is obtained by free radical copolymerization of unsaturated phosphoric acid monomers, unsaturated carboxylic acid monomers, unsaturated branched polyethers and unsaturated crosslinking monomers. By introducing branched polyether side chains into molecular side chains, the spatial configuration and stretching degree of the concrete admixture in a concrete multiphase system can be regulated. By introducing carboxylic acid and phosphoric acid groups and hydrolyzable crosslinking monomers into the main chain of the molecule, the lubrication effect and hydrophilic state of the concrete can be improved, the collapse resistance of the concrete mixture can be improved, and the time-dependent loss of the concrete can be reduced. The concrete mixture can be made to have high fluidity, high separation resistance, high filling property and high gap passing capacity. The hardened concrete has excellent mechanical properties and durability, and the compressive strength reaches above 50Mpa. The water reducer is added in a small amount, the cost can be reduced, and the adaptability to engineering applications is strong.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a phosphoric acid-based water reducer specially used for highly robust self-compacting concrete and a preparation method thereof. Background Art

[0002] In recent years, my country's infrastructure construction has flourished, especially the demand for high-performance concrete in large-scale special buildings such as high-speed railways, bridges, and tunnels has increased day by day. High-performance concrete is undoubtedly an important direction for future development. Among the many branches of high-performance concrete, self-compacting concrete, as an important content, has also become a research hotspot in recent years. Although self-compacting concrete has the characteristics of high fluidity, no segregation, and no water seepage, and can flow in the formwork by relying solely on its own weight without vibration, it can achieve uniform, stable, and good construction performance. In engineering buildings with special structures, it can be used in locations that are difficult to cast or cannot be cast, which not only saves economic costs, but also avoids the defects of voids and rough surfaces caused by vibration. However, self-compacting concrete usually has relatively low mechanical properties and poor durability. On the other hand, the water reducer used in self-compacting concrete usually has reduced dispersion performance due to the presence of soil in the material, and the dosage is usually increased to solve the problem of low water reduction rate, which not only increases the cost, but also may cause water bleeding in the initial concrete. In addition, if the water reducer and self-compacting concrete cannot be effectively matched, the self-compacting concrete will have poor fluidity, increased viscosity, and larger and more bubbles. The final product may have internal defects, making the product uneven and discontinuous, and the appearance is relatively rough, which directly affects the mechanical properties of the concrete and limits its application in engineering.

[0003] Phosphate-based water reducer is a new type of functional water reducer newly discovered and studied on the basis of polycarboxylate water reducer. The phosphate-based water reducer molecule contains a phosphate group, which contains two negative charges and has stronger adsorption capacity and speed than the polycarboxylate group. It is preferentially adsorbed on the surface of stone powder and clay, avoiding the adsorption of carboxyl groups on cement particles, and ensuring the adsorption and dispersion performance of polycarboxylate water reducer; on the other hand, the phosphate group can improve the tolerance of the water reducer itself to calcium ions in the cement slurry system. In addition, it has also been reported that the phosphate group can delay cement hydration, delay the loss of concrete state, and reduce the adverse effects of clay and sulfate on water reducers. At present, there are many patents and documents that disclose the preparation method of phosphate-based water reducer and the effects achieved: it has obvious collapse retention, slow setting, water reduction performance and certain anti-clay ability, without losing other properties such as the strength of concrete. However, the phosphate-based water reducers reported for self-compacting concrete have improved water reduction and slump retention compared to polycarboxylic acid water reducers. However, in the long-term slump retention and in concrete containing a certain amount of soil, the phosphate-based water reducers sometimes cannot fully and effectively exert their performance, and may also have a certain degree of shrinkage problems, produce harmful cracks, reduce the waterproof and impermeability of the self-compacting concrete; and also reduce the mechanical properties of the concrete. Therefore, adjusting and designing the molecular structure based on the existing phosphate-based water reducers may reduce the adverse effects of aggregates mixed with soil, which is of great significance in improving and enhancing the mechanical properties and stability of self-compacting concrete.

[0004] Patent CN107987271 A reports a method for preparing a low molecular weight water reducer containing a phosphate ester group: firstly, a low molecular weight chlorinated polyether is reacted with an aminating agent to obtain an aminated polyether, which is then subjected to a hyperbranching modification and then subjected to a Mannich reaction with phosphorous acid to finally obtain a terminal hyperbranched phosphate ester-based low molecular weight water reducer. The preparation process of such a water reducer is slightly cumbersome, and the control of the reaction degree is difficult. At the same time, the water reducer contains chlorine in the preparation process, and even if it has been strictly treated, the removal of the chlorine element cannot be guaranteed, which may have an adverse effect on the building materials during use.

[0005] Patent CN103596993A discloses a copolymer with a geminal bisphosphate group, the copolymer having a main hydrocarbon chain and a side group, the side group including a carboxyl group and a polyoxyalkyl group, and also including a geminal bisphosphate group. This type of polymer has low sensitivity to clay and alkaline sulfide in cement relative to polycarboxylic acid water reducer. However, this method uses PCl3 as a reaction raw material, which is a strictly controlled compound that is very easy to react with water and is also easily oxidized. It is active in reaction and releases a lot of heat at the same time. It is not easy to preserve, and the process is difficult to realize industrialization. At the same time, in the synthesis reaction, the chlorine element may still not be effectively avoided in the end.

[0006] Patent CN111362612A discloses a self-compacting concrete water reducer, which introduces phosphoric acid groups into the main chain and side chain of polycarboxylic acid to prepare a phosphoric acid-containing water reducer. After use, the concrete has good stability and high fluidity. Although the early strength and late strength of the concrete are improved, we believe that there is still room for improvement; at the same time, six monomers are used in the patent, which not only has high raw material costs, but also has complex process operations, making it difficult to form large-scale production and not conducive to industrialization.

[0007] Therefore, it is necessary to design a special admixture for self-compacting concrete, which can make the self-compacting concrete have high fluidity, high strength and excellent stability under certain conditions. A large number of studies have shown that as a new type of functional water reducer, phosphate-based water reducer may have certain application prospects in improving the mechanical properties and stability of self-compacting concrete. Summary of the invention

[0008] In order to partially solve the above technical problems, the present invention provides a phosphate-based water reducer for highly robust self-compacting concrete and a preparation method thereof. By introducing branched polyether side chains in the molecular side chains, the spatial configuration and stretching degree of the concrete admixture in the concrete multiphase system can be regulated; by introducing carboxylic acid and phosphoric acid groups and hydrolyzable cross-linking monomers in the molecular main chain, the lubrication effect and hydrophilic state of the concrete can be improved, the collapse resistance of the concrete mixture can be improved, and the time-dependent loss of the concrete can be reduced. The phosphate-based water reducer for highly robust self-compacting concrete of the present invention can make the concrete mixture have high fluidity, high resistance to separation, high filling and high gap passing capacity after addition; the mechanical properties and durability of the hardened concrete are excellent, and the compressive strength reaches more than 50Mpa; the phosphate-based water reducer for highly robust self-compacting concrete has a small dosage, which can reduce costs and has strong adaptability to engineering applications.

[0009] The phosphoric acid-based water reducer for highly robust self-compacting concrete is obtained by free radical copolymerization of unsaturated phosphoric acid monomer, unsaturated carboxylic acid monomer, unsaturated branched polyether and unsaturated cross-linking monomer; the molar ratio of the unsaturated branched polyether, unsaturated phosphoric acid monomer, unsaturated carboxylic acid monomer and unsaturated cross-linking monomer is 1:(1-5):(2-4):(0.1-0.5); the weight average molecular weight of the phosphoric acid-based water reducer for highly robust self-compacting concrete is 60000-80000; the structure of the unsaturated branched polyether monomer is shown in general formula (1) and general formula (2):

[0010]

[0011] Wherein, R1 is H or CH3; R2 is C n H 2n, n is a positive integer ranging from 2 to 10; x1, x2, x3, and x4 are positive integers ranging from 10 to 100 and are independent of each other; y1, y2, y3, and y4 are positive integers ranging from 1 to 10 and are independent of each other.

[0012] The weight average molecular weight of the unsaturated branched polyether monomer is 500-5000.

[0013] The weight average molecular weight of the unsaturated branched polyether monomer is preferably 1000-3000.

[0014] The unsaturated branched polyether is prepared by the following steps: (a) preparation of an initiator: placing an unsaturated alcohol and a catalyst in a reaction container, dripping glycidol into the container, and after the dripping and reaction are completed, removing excess glycidol by a reduced pressure distillation method to obtain an initiator; (b) preparation of an unsaturated branched polyether: reacting the initiator with propylene oxide and ethylene oxide in the presence of a catalyst, cooling, degassing, and discharging to obtain an unsaturated branched polyether.

[0015] The glycidol is added dropwise for 1-2 hours in the step (a); the reaction is carried out at 40-60° C. for 2-5 hours after the addition is completed; the molar ratio of the unsaturated alcohol to the glycidol in the step (a) is 1:(1.0-1.1); the catalyst in the step (a) is any one of metallic sodium, metallic potassium, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium hydroxide, potassium hydroxide, sodium hydride and potassium hydride; the mass of the catalyst in the step (a) is 0.1%-0.5% of the mass of the unsaturated alcohol.

[0016] In the step (b), nitrogen replacement is first performed before the reaction, the reaction temperature is 80-120° C., the reaction pressure is 1:≤-0.07MPa, and the reaction time is 0.5-1h; the alkylene oxide in the step (b) includes any one of ethylene oxide, propylene oxide, tetrahydrofuran, isobutylene oxide, cyclopentene oxide, and cyclohexene oxide, preferably ethylene oxide and propylene oxide; the epoxy compound in the step (b) is a mixture of ethylene oxide and propylene oxide, and the molar ratio of the initiator, propylene oxide, and ethylene oxide is 1:(1.0-5.0):(15.0-70.0); the catalyst in the step (b) is any one of metallic sodium, metallic potassium, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium hydroxide, potassium hydroxide, sodium hydride, and potassium hydride; the amount of the catalyst in the step (b) is 0.1%-0.5% of the mass of the initiator.

[0017] The structure of the unsaturated carboxylic acid monomer is shown in the general formula (3):

[0018]

[0019] Wherein, R3 is H or COOM; R4 is H, CH3 or CH2COOM; and when R3 is COOM, R4 is H; M is any one of a hydrogen atom, an alkali metal ion, an alkaline earth metal ion, an ammonium ion or an organic amine group.

[0020] The above unsaturated phosphoric acid monomer has the general structural formula (4) shown below:

[0021]

[0022] Where R5 is H or CH3; when X is C n H 2n When n is a positive integer in the range of 1 to 18; when X is COO-C n H 2n Or when X is CO-NH-C n H 2n When n is a positive integer in the range of 1 to 10.

[0023] The unsaturated phosphoric acid monomer is selected from any one of 2-acryloxyethyl phosphate, 2-acryloxypropyl phosphate, 2-methacryloxyethyl phosphate, 2-methacryloxypropyl phosphate, 2-acrylamideethyl phosphate, 2-acrylamide-propyl phosphate, and 2-acrylamide-butyl phosphate; the unsaturated cross-linking monomer is a polyethylene glycol acrylate compound, and the weight average molecular weight of the unsaturated cross-linking monomer is 500-1000; the unsaturated cross-linking monomer is selected from any one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and polyethylene glycol maleic acid diester.

[0024] A highly robust phosphate-based water-reducing agent for self-compacting concrete comprises the following steps: (1) preparing a base material: adding an unsaturated branched polyether and water into a reactor, stirring at room temperature to completely dissolve the unsaturated branched polyether, and obtaining a base material; (2) preparing a droplet A: adding a reducing agent and a chain transfer agent into water, stirring evenly, and obtaining a droplet A; (3) preparing a droplet B: adding an unsaturated carboxylic acid monomer and an unsaturated phosphoric acid monomer into water, stirring evenly, and obtaining a droplet B; (4) preparing a droplet C: adding an unsaturated cross-linking monomer into water, stirring evenly, and obtaining a droplet B; , stirring evenly to obtain droplet C; (5) adding the oxidant to the base material, stirring for 5-10 minutes, and then adding droplet A, droplet B and droplet C to the reactor in sequence at a reaction temperature of 40-60°C, and continuing to keep warm for (1.0-2.0) hours after the addition; (6) after the reaction is completed, neutralize with an alkaline solution with a mass fraction of 20%-75% to a pH value of 5.0-7.0, cool to room temperature, and then add water to form a solution to obtain a phosphate-based water reducer specially used for highly robust self-compacting concrete.

[0025] In the above step (5), the dropping time of the dropwise addition liquid A is (4.0-4.5) h, the dropping time of the dropwise addition liquid B is (3.0-4.0) h, and the dropping time of the dropwise addition liquid C is (4.0-4.5) h.

[0026] In the above step (6), the alkaline solution is an aqueous solution of a hydroxide of a positive monovalent or positive divalent metal or a carbonate thereof; the solid content of the highly robust self-compacting concrete-specific phosphate-based water reducer obtained in the above step (6) is 25%-50%.

[0027] The reducing agent is one of ascorbic acid and sodium bisulfite; the oxidizing agent is any one of hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate; the total mass of the reducing agent and the oxidizing agent is 0.5%-5.0% of the total mass of all unsaturated monomers, and the mass ratio of the reducing agent to the oxidizing agent is 1:1; the chain transfer agent is any one of mercaptoethanol, thioglycolic acid, 2-mercaptopropionic acid and 3-mercaptopropionic acid; the amount of the chain transfer agent is 0.5%-5.0% of the total mass of all unsaturated monomers.

[0028] The invention discloses an application of a phosphoric acid-based water reducer specially used for highly robust self-compacting concrete in a special admixture for self-compacting concrete. The special admixture for self-compacting concrete comprises the following raw materials in parts by weight: 150-250 parts of the phosphoric acid-based water reducer specially used for highly robust self-compacting concrete; 120-150 parts of a slump retaining agent; 0.5-1.5 parts of a water retaining agent; 20-30 parts of a retarder; 2-5 parts of a thickener; 0.1-0.8 parts of a defoaming agent; and 80-135 parts of water.

[0029] The above-mentioned collapse preventing agent is a polycarboxylic acid-based collapse preventing agent, and the weight average molecular weight ranges from 40,000 to 60,000.

[0030] The water retaining agent is any one of cold water instant soluble powdered methyl cellulose ether or hydroxyethyl cellulose ether.

[0031] The retarder is a compound of any one or more of sodium gluconate, sucrose, dextrin and citric acid.

[0032] The defoaming agent includes any one of a polyether-modified silicon defoaming agent and an organic silicon defoaming agent.

[0033] The thickener includes any one of polyacrylamide and sodium polyacrylate, and the viscosity average molecular weight is 1 million to 3 million.

[0034] The defoaming agent includes any one of a polyether-modified silicon defoaming agent and an organic silicon defoaming agent.

[0035] The corresponding weight portions of a phosphate-based water reducer, a slump retaining agent, a water retaining agent, a retarder, a defoaming agent and water for high-robustness self-compacting concrete are fully mixed to obtain a mixture; then the corresponding weight portions of a thickener are added and fully mixed to obtain a special admixture for self-compacting concrete.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. The present invention can regulate the spatial configuration and stretching degree of the concrete admixture in the concrete multiphase system by introducing branched polyether side chains into the molecular side chains, so that the concrete has better dispersibility;

[0038] 2. The present invention can improve the lubrication effect and hydrophilic state of concrete, enhance the slump resistance of concrete mixture, and reduce the loss of concrete over time by introducing carboxylic acid and phosphoric acid groups and hydrolyzable cross-linking monomers into the main chain of the molecule: in the concrete bounce flow test, the loss in 2 hours can be less than 5%;

[0039] 3. The phosphate-based water reducer specially used for highly robust self-compacting concrete of the present invention can make the concrete mixture have high fluidity, high resistance to separation, high filling property and high gap passing capacity after being added; the hardened concrete has excellent mechanical properties and durability, and the compressive strength reaches more than 50Mpa; the phosphate-based water reducer specially used for highly robust self-compacting concrete has a small dosage, which can reduce costs and has strong adaptability to engineering applications.

[0040] The entire preparation process of the present invention is simple, controllable, efficient and convenient. The steps used in the reaction are all common operating processes, no special operations or expensive additives are required, the reaction conditions are mild, and the process is green and environmentally friendly. Therefore, it is easy to realize industrial production and has good promotion potential and application value. DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The weight average molecular weight of the polymer in the present invention is determined by gel permeation chromatography (gel column: Shodex SB806+803 chromatographic columns connected in series; eluent: 0.1M NaNO3 aqueous solution; mobile phase speed: 0.8mL / min; injection: 20μL of 0.5% aqueous solution; detector: Shodex RI-71 differential refractometer; standard: polyethylene glycol GPC standard (Sigma-Aldrich molecular weight 1010000, 478000, 263000, 118000, 44700, 18600, 6690, 1960, 628, 232).

[0043] Preparation of starting agent:

[0044] Add 86g (1mol) of isopentanol and 25.2g (1.05mol) of sodium hydride catalyst to the reaction vessel, stir at room temperature for 1h until the system is stable without gas release. Add 77.7g (1.05mol) of glycidol dropwise to the reaction vessel for 2h, react at 40°C for 3h, filter to remove the solid, collect the liquid component, and finally remove the excess glycidol in the liquid component by vacuum distillation to obtain initiator S1;

[0045] Add 72g (1mol) of methyl allyl alcohol and 25.2g (1.05mol) of sodium hydride catalyst to the reaction vessel, stir at room temperature for 1h until the system is stable without gas release. Add 77.7g (1.05mol) of glycidol dropwise to the reaction vessel for 2h, react at 40°C for 3.5h, filter to remove the solid, collect the liquid component, and finally remove the excess glycidol in the liquid component by vacuum distillation to obtain initiator S2.

[0046] Preparation of unsaturated branched polyethers:

[0047] 160g (1mol) of initiator S1 and 0.32g of NaOH were added to a 1L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 130g of propylene oxide was slowly introduced into the system, and then 800g of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain a branched polyether, which was recorded as E1. The weight average molecular weight was 1053 as determined by aqueous gel permeation chromatography.

[0048] 160g (1mol) of initiator S1 and 0.32g of KOH were added to a 1L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 130g of propylene oxide was slowly introduced into the system, and then 1800g of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain a branched polyether, which was recorded as E2. The weight average molecular weight was 1996 as determined by aqueous gel permeation chromatography.

[0049] 160g (1mol) of initiator S1 and 0.32g of NaOH were added to a 1L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 130g of propylene oxide was slowly introduced into the system, and then 2800g of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain a branched polyether, which was recorded as E3. The weight average molecular weight was 3135 as determined by aqueous gel permeation chromatography.

[0050] 146g (1 mol) of initiator S2 and 0.48g NaH were added to a 1L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 130g of propylene oxide was slowly introduced into the system, and then 800g of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain a branched polyether, which was recorded as E4. The weight average molecular weight was 1125 as determined by aqueous gel permeation chromatography.

[0051] 146g (1 mol) of initiator S2 and 0.48g of NaOH were added to a 1L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 130g of propylene oxide was slowly introduced into the system, and then 1800g of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain a branched polyether, which was recorded as E5. The weight average molecular weight was 2203 as determined by aqueous gel permeation chromatography.

[0052] 146g (1mol) of initiator S2 and 0.48g of KH were added to a 1L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 130g of propylene oxide was slowly introduced into the system, and then 2800g of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain a branched polyether, which was recorded as E6. The weight average molecular weight was 3329 as determined by aqueous gel permeation chromatography.

[0053] Embodiment 1:

[0054] (1) Add 100 g (0.1 mol) of self-made polyether E1 (weight average molecular weight 1053) to a reaction vessel, then add water and stir for 5-10 min;

[0055] (2) Sodium bisulfite (1.65 g), mercaptoethanol (1.25 g) and water were mixed evenly, and the mixture was recorded as dropwise solution A1;

[0056] (3) 14.4 g (0.2 mol) of acrylic acid, 42 g (0.2 mol) of 2-methacryloyloxyethyl phosphate and water were mixed uniformly, and the mixture was recorded as dropwise solution B1;

[0057] (4) 8 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 800) was added to water and stirred to obtain a dropwise solution C1;

[0058] (5) Add ammonium persulfate (1.56 g) into the reactor, stir for 5 min, and heat to 50° C., then start adding dropwise solution A1 for 4.0 h; dropwise solution B1 for 3.0 h; dropwise solution C1 for 4.0 h; keep warm for 2.0 h after the addition is complete;

[0059] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 6.5 using a 40% by mass sodium hydroxide solution and water to obtain a highly robust self-compacting concrete special phosphate-based water reducer, denoted as PS-1. The weight average molecular weight determined by aqueous gel permeation chromatography is 58952.

[0060] Embodiment 2:

[0061] (1) Add 200 g (0.1 mol) of self-made polyether E2 (weight average molecular weight 1996) into a reaction vessel, then add water and stir for 5-10 min;

[0062] (2) Mix ascorbic acid (1.65 g), thioglycolic acid (2.05 g) and water, and record it as dropwise solution A2;

[0063] (3) 14.4 g (0.2 mol) of acrylic acid, 44.8 g (0.2 mol) of 2-methacryloyloxypropyl phosphate and water were mixed uniformly, and the mixture was recorded as dropwise solution B2;

[0064] (4) adding 8 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 800) into water and stirring evenly to obtain a dropwise solution C2;

[0065] (5) Sodium persulfate (1.56 g) was added to the reactor and stirred for 5 min. After the temperature was raised to 50° C., the dropping liquid A2 was started for 4.5 h. The dropping liquid B2 was added for 3.5 h. The dropping liquid C2 was added for 4.0 h. After the dropping was completed, the temperature was kept at room temperature for 2.0 h.

[0066] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized with 40% by mass sodium hydroxide solution and water to a pH value of 6.2. Water is then added to obtain a highly robust phosphate-based water reducer for self-compacting concrete, which is denoted as PS-2. The weight average molecular weight is 63952 as determined by aqueous gel permeation chromatography.

[0067] Embodiment 3:

[0068] (1) Add 300 g (0.1 mol) of self-made polyether E3 (weight average molecular weight 3135) into a reaction vessel, then add water and stir for 5-10 min;

[0069] (2) Sodium bisulfite (3.60 g), mercaptopropionic acid (2.85 g) and water were mixed uniformly, and the mixture was recorded as dropwise solution A3;

[0070] (3) 17.4 g (0.2 mol) of methacrylic acid, 39.2 g (0.2 mol) of 2-acryloyloxyethyl phosphate and water were mixed uniformly, and the mixture was recorded as dropwise solution B3;

[0071] (4) 8 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 800) was added to water and stirred evenly to obtain a dropwise solution C3;

[0072] (5) Potassium persulfate (3.56 g) was added to the reactor and stirred for 5 min. After the temperature was raised to 50° C., the dropping liquid A3 was started, and the dropping time was 4.5 h; the dropping time of the dropping liquid B3 was 3.5 h; the dropping time of the dropping liquid C3 was 4.0 h; after the dropping was completed, the temperature was kept warm for 2.0 h;

[0073] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 5.8 using a 40% by mass sodium hydroxide solution and water to obtain a highly robust self-compacting concrete special phosphate-based water reducer, denoted as PS-3. The weight average molecular weight is 76385 as determined by aqueous gel permeation chromatography.

[0074] Embodiment 4:

[0075] (1) Add 100 g (0.1 mol) of self-made polyether E4 (weight average molecular weight 1125) to a reaction vessel, then add water and stir for 5-10 min;

[0076] (2) Mix ascorbic acid (1.58 g), mercaptoethanol (1.25 g) and water, and record it as dropwise solution A4;

[0077] (3) 14.4 g (0.2 mol) of acrylic acid, 42 g (0.2 mol) of 2-acryloxypropyl phosphate and water were mixed uniformly, and the mixture was recorded as dropwise solution B4;

[0078] (4) Add 6 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 600) into water and stir evenly to obtain a dropwise solution C4;

[0079] (5) Add hydrogen peroxide (1.56 g) to the reactor, stir for 5 min, and heat to 50°C. Then, start adding dropwise solution A4 for 4.0 h; dropwise solution B4 for 3.0 h; dropwise solution C4 for 4.0 h. After the addition is complete, continue to keep the temperature for 2.0 h.

[0080] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 6.3 using a 40% by mass sodium hydroxide solution and water to obtain a highly robust self-compacting concrete special phosphate-based water reducer, denoted as PS-4. The weight average molecular weight is 60038 as determined by aqueous gel permeation chromatography.

[0081] Embodiment 5:

[0082] (1) Add 200 g (0.1 mol) of self-made polyether E5 (weight average molecular weight 2203) into a reaction vessel, then add water and stir for 5-10 min;

[0083] (2) Sodium bisulfite (1.68 g), mercaptoethanol (2.05 g) and water were mixed evenly, and the mixture was recorded as dropwise solution A5;

[0084] (3) 14.4 g (0.2 mol) of acrylic acid, 39 g (0.2 mol) of 2-acrylamidoethylphosphoric acid and water were uniformly mixed, and the mixture was recorded as dropwise solution B5;

[0085] (4) adding 7 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 700) into water and stirring uniformly to obtain a dropwise solution C5;

[0086] (5) Add ammonium persulfate (1.56 g) into the reactor, stir for 5 min and heat to 50°C, then start adding dropwise solution A5 for 4.5 h; dropwise solution B5 for 3.5 h; dropwise solution C5 for 4.0 h; keep warm for 2.0 h after the addition is complete;

[0087] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 6.5 using a 40% by mass sodium hydroxide solution and water to obtain a highly robust self-compacting concrete special phosphate-based water reducer, denoted as PS-5. The weight average molecular weight determined by aqueous gel permeation chromatography is 66342.

[0088] Embodiment 6:

[0089] (1) Add 300 g (0.1 mol) of homemade polyether E6 (weight average molecular weight 3329) to a reaction vessel, then add water and stir for 5-10 min;

[0090] (2) Sodium bisulfite (3.68 g), mercaptoethanol (2.85 g) and water were mixed uniformly, and the mixture was recorded as dropwise solution A6;

[0091] (3) 14.4 g (0.2 mol) of acrylic acid, 41.8 g (0.2 mol) of 2-methacrylamide ethyl phosphoric acid and water were mixed uniformly, and the mixture was recorded as dropwise solution B6;

[0092] (4) adding 9 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 900) into water and stirring uniformly to obtain a dropwise solution C6;

[0093] (5) Potassium persulfate (3.56 g) was added to the reactor and stirred for 5 min. After the temperature was raised to 50°C, the dropping liquid A6 was started for 4.5 h; the dropping liquid B6 was added for 3.5 h; the dropping liquid C6 was added for 4.0 h. After the dropping was completed, the temperature was kept at room temperature for 2.0 h.

[0094] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 6.2 using a 40% by mass sodium hydroxide solution and water. Water is then added to obtain a highly robust phosphate-based water reducer for self-compacting concrete, which is denoted as PS-6. The weight average molecular weight is 76625 as determined by aqueous gel permeation chromatography.

[0095] Embodiment 7:

[0096] (1) Add 100 g (0.1 mol) of self-made polyether E1 (weight average molecular weight 1000) to a reaction vessel, then add water and stir for 5-10 min;

[0097] (2) Sodium bisulfite (2.69 g), mercaptopropionic acid (1.25 g) and water were mixed uniformly, and the mixture was recorded as dropwise solution A7;

[0098] (3) 17.4 g (0.2 mol) of methacrylic acid, 42 g (0.2 mol) of 2-methacryloyloxyethyl phosphate and water were mixed uniformly, and the mixture was recorded as dropwise solution B7;

[0099] (4) 8 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 800) was added to water and stirred to obtain a dropwise solution C7;

[0100] (5) Add hydrogen peroxide (1.56 g) to the reactor, stir for 5 min, and heat to 50°C. Then, start dripping liquid A7 for 4.0 h; drip liquid B7 for 3.0 h; drip liquid C7 for 4.0 h. After the dripping is complete, continue to keep warm for 2.0 h.

[0101] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 6.5 using a 40% by mass sodium hydroxide solution and water to obtain a highly robust self-compacting concrete special phosphate-based water reducer, denoted as PS-7. The weight average molecular weight is 62335 as determined by aqueous gel permeation chromatography.

[0102] Embodiment 8:

[0103] (1) Add 200 g (0.1 mol) of self-made polyether E2 (weight average molecular weight 2000) to a reaction vessel, then add water and stir for 5-10 min;

[0104] (2) Mix potassium bisulfite (1.62 g), thioglycolic acid (2.05 g) and water, and record it as dropwise addition liquid A8;

[0105] (3) 14.4 g (0.2 mol) of acrylic acid, 39.2 g (0.2 mol) of 2-acryloyloxyethyl phosphate and water were uniformly mixed, and the mixture was recorded as dropwise solution B8;

[0106] (4) adding 9 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 900) into water and stirring uniformly to obtain a dropwise solution C8;

[0107] (5) Add ammonium persulfate (1.56 g) into the reactor, stir for 5 min and heat to 50° C., then start adding dropwise solution A5 for 4.5 h; dropwise solution B8 for 3.5 h; dropwise solution C8 for 4.0 h; keep warm for 2.0 h after the addition is complete;

[0108] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 6.5 using a 40% by mass sodium hydroxide solution and water to obtain a highly robust self-compacting concrete special phosphate-based water reducer, denoted as PS-8, with a weight average molecular weight of 63652 as measured by aqueous gel permeation chromatography.

[0109] Embodiment 9:

[0110] (1) Add 300 g (0.1 mol) of self-made polyether E3 (weight average molecular weight 3000) into a reaction vessel, then add water and stir for 5-10 min;

[0111] (2) ascorbic acid (3.63 g), 3-mercaptopropionic acid (2.85 g) and water were mixed uniformly, and the mixture was recorded as dropwise solution A3;

[0112] (3) 17.4 g (0.2 mol) of methacrylic acid, 44.8 g (0.2 mol) of 2-methacryloyloxypropyl phosphate and water were mixed uniformly, and the mixture was recorded as dropwise solution B9;

[0113] (4) adding 7 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 700) into water and stirring uniformly to obtain a dropwise solution C9;

[0114] (5) Potassium persulfate (3.56 g) was added to the reactor and stirred for 5 min. After the temperature was raised to 50° C., the dropping liquid A3 was started to be added dropwise for 4.5 h; the dropping liquid B9 was added dropwise for 3.5 h; the dropping liquid C9 was added dropwise for 4.0 h; after the addition was completed, the temperature was kept warm for 2.0 h;

[0115] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 5.8 using a 40% by mass alkali solution and water to obtain a highly robust self-compacting concrete special phosphate-based water reducer, denoted as PS-9. The weight average molecular weight is 78386 as determined by aqueous gel permeation chromatography.

[0116] Comparative Example 1:

[0117] (1) Add 200 g (0.1 mol) of methyl allyl polyoxyethylene ether (commercially available) (molecular weight 2000) into a reaction container, then add water and stir for 5-10 min;

[0118] (2) Mix sodium bisulfite (2.56 g), thioglycolic acid (2.05 g) and water, and record it as dropwise solution Ad1;

[0119] (3) 17.4 g (0.2 mol) of methacrylic acid, 42 g (0.2 mol) of hydroxyethyl methacrylate phosphate and water were mixed evenly, and the mixture was recorded as dropwise solution Bd1;

[0120] (4) 8 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 800) was added to water and stirred to obtain a drop solution Cd1;

[0121] (5) Add ammonium persulfate (1.56 g) into the reactor, stir for 5 min, and heat to 50°C, then start adding dropwise solution Ad1 for 4.5 h; dropwise solution Bd1 for 3.5 h; dropwise solution Cd1 for 4.0 h. After the addition is complete, continue to keep warm for 2.0 h;

[0122] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized with an alkaline solution having a mass fraction of 20%-75% to a pH value of 5.0-7.0, and then water is added to obtain a phosphate-based water reducer, which is denoted as S0-1. The weight average molecular weight is 64531 as determined by aqueous gel permeation chromatography.

[0123] Comparative Example 2:

[0124] (1) Add 200 g (0.1 mol) of homemade polyether E5 (molecular weight 2000) into a reaction vessel, then add water and stir for 5-10 min;

[0125] (2) Mix potassium bisulfite (2.56 g), mercaptopropionic acid (2.05 g) and water, and record it as dropwise solution Ad2;

[0126] (3) Mix 28.8 g (0.4 mol) of acrylic acid and water, and record it as dropwise solution Bd2;

[0127] (4) adding 7 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 700) into water and stirring evenly to obtain a dropwise solution Cd2;

[0128] (5) Add ammonium persulfate (1.56 g) into the reactor, stir for 5 min and heat to 50°C, then start adding dropwise solution Ad2 for 4.5 h; dropwise solution Bd2 for 3.5 h; dropwise solution Cd2 for 4.0 h; keep warm for 2.0 h after the addition is complete;

[0129] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized with an alkaline solution having a mass fraction of 20%-75% to a pH value of 5.0-7.0, and then water is added to obtain a phosphate-based water reducer, which is denoted as S0-2. The weight average molecular weight is 62361 as determined by aqueous gel permeation chromatography.

[0130] Comparative Example 3:

[0131] (1) Add 200 g (0.1 mol) of homemade polyether E5 (molecular weight 2000) into a reaction vessel, then add water and stir for 5-10 min;

[0132] (2) ascorbic acid (2.56 g), mercaptoethanol (2.05 g) and water were mixed evenly, and the mixture was recorded as dropwise solution Ad3;

[0133] (3) 14.4 g (0.2 mol) of acrylic acid, 44.8 g (0.2 mol) of hydroxypropyl methacrylate phosphate and water were mixed evenly, and the mixture was recorded as dropwise solution Bd3;

[0134] (4) Sodium persulfate (2.56 g) was added to the reactor and stirred for 5 min. After the temperature was raised to 50° C., the dropping liquid Ad3 was added dropwise for 4.5 h. The dropping liquid Bd3 was added dropwise for 3.5 h. After the addition was completed, the temperature was kept constant for 2.0 h.

[0135] (5) After the reaction is completed, the temperature is lowered to room temperature and then neutralized to a pH value of 6.2 with a 40% by mass alkali solution and water, and then water is added to obtain a phosphate-based water reducer, which is denoted as S0-3. The weight average molecular weight is 58783 as determined by aqueous gel permeation chromatography.

[0136] Comparative Example 4:

[0137] (1) Add 200 g (0.1 mol) of homemade polyether E5 (molecular weight 2000) to a reaction vessel, then add water and stir for 5-10 min;

[0138] (2) ascorbic acid (2.56 g), mercaptoethanol (2.05 g) and water were mixed evenly, and the mixture was recorded as dropwise solution Ad4;

[0139] (3) 14.4 g (0.2 mol) of acrylic acid, 44.8 g (0.2 mol) of hydroxypropyl methacrylate phosphate and water were mixed evenly, and the mixture was recorded as dropwise solution Bd4;

[0140] (4) 7 g (0.01 mol) of divinyl polyether (weight average molecular weight 700) was added to water and stirred to obtain a dropwise solution Cd4;

[0141] (5) Sodium persulfate (2.56 g) was added to the reactor and stirred for 5 min. After the temperature was raised to 50° C., the dropping liquid Ad4 was added dropwise for 4.5 h; the dropping liquid Bd4 was added dropwise for 3.5 h; the dropping liquid Cd4 was added dropwise for 4.0 h; after the addition was completed, the temperature was kept warm for 2.0 h;

[0142] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized with 40% by mass alkali solution and water to a pH value of 6.2. Water is then added to obtain a phosphate-based water reducer, which is designated as S0-4. The weight average molecular weight is 58783 as determined by aqueous gel permeation chromatography.

[0143] Comparative Example 5:

[0144] (1) Add 300 g (0.1 mol) of self-made polyether E3 (weight average molecular weight 3135) into a reaction vessel, then add water and stir for 5-10 min;

[0145] (2) Sodium bisulfite (3.56 g), mercaptopropionic acid (2.85 g) and water were mixed and added to a reaction vessel;

[0146] (3) 17.4 g (0.2 mol) of methacrylic acid, 39.2 g (0.2 mol) of 2-acryloyloxyethyl phosphate and water were mixed evenly and added to a reaction vessel;

[0147] (4) 8 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 800) was added to water, stirred evenly, and added to the reaction vessel;

[0148] (5) Hydrogen peroxide (2.56 g) was added to the reactor and stirred for 5 min. The temperature was raised to 50 °C and then kept at this temperature for 2.0 h.

[0149] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized with 40% by mass sodium hydroxide solution and water to a pH value of 6.0 to obtain a phosphate-based water reducer, which is denoted as S0-5. The weight average molecular weight is 56385 as determined by aqueous gel permeation chromatography.

[0150] Comparative Example 6:

[0151] (1) Add 200 g (0.1 mol) of methyl allyl polyoxyethylene ether (molecular weight 2000) into a reaction vessel, then add water and stir for 5-10 min;

[0152] (2) ascorbic acid (2.56 g) and 3-mercaptopropionic acid (2.05 g) were mixed with water and recorded as dropwise solution Ad6;

[0153] (3) 14.4 g (0.2 mol) of acrylic acid, 42 g (0.2 mol) of hydroxyethyl methacrylate phosphate and water were mixed evenly, and the mixture was recorded as dropwise solution Bd6;

[0154] (4) 8 g (0.01 mol) of polyethylene glycol diacrylate (weight average molecular weight 800) was added to water and stirred evenly to obtain a dropwise solution Cd6;

[0155] (5) Sodium persulfate (1.56 g) was added to the reactor and stirred for 5 min. After the temperature was raised to 50°C, the dropping liquid Ad6 was started. The dropping time was 4.5 h. The dropping time of the dropping liquid Bd6 was 3.5 h. The dropping time of the dropping liquid Cd6 was 4.0 h. After the dropping was completed, the temperature was kept at 5.0 h.

[0156] (6) After the reaction is completed, the temperature is lowered to room temperature and then neutralized with 40% by mass sodium hydroxide solution and water to a pH value of 6.5, and then water is added to obtain a phosphate-based water reducer, which is denoted as S0-6. The weight average molecular weight is 105252 as determined by aqueous gel permeation chromatography.

[0157] Preparation of special admixtures for self-compacting concrete:

[0158] According to the sample composition of the self-compacting concrete admixture in Table 1, the corresponding weight portions of the high-robustness self-compacting concrete special phosphate-based water reducer, slump retainer, water retainer, retarder, defoamer and water are fully mixed to obtain a mixture; then the corresponding weight portions of thickener are added and fully mixed to obtain the self-compacting concrete special admixtures SCCA-1 to 9 and the comparative examples SCCA0-1 to 6.

[0159] Table 1:

[0160]

[0161]

[0162] Mechanical and working performance tests are carried out in accordance with the relevant provisions of the "Technical Code for Application of Self-compacting Concrete" (JGJ / T283-2012) and the "Standard for Test Methods for Mechanical Properties of Ordinary Concrete" (GB / T500081-2002), as well as anti-permeability tests.

[0163] Test 1: Slump flow test

[0164] Test method:

[0165] 1. Preparation of test samples: 0.35t of PO 42.5 cement and 0.10t of grade II fly ash were used to prepare 8.1kg of the corresponding admixtures in Examples 1-9, and 0.54m of medium sand was added. 3 , the particle size is 4.75mm-31.5mm, the stone is 0.594m 3 , add 0.170m3 of water 3 After uniform mixing, the initial slump flow and 2h slump expansion were tested to obtain test samples SCCA-1 to 9 respectively.

[0166] 2. Preparation of comparative samples: 8.1 kg of the corresponding admixtures in Comparative Examples 1-6 were prepared using 0.35 t of PO 42.5 cement and 0.10 t of Class II fly ash, and then 0.54 m of medium sand was added. 3 , the particle size is 4.75mm-31.5mm, the stone is 0.594m 3 , add 0.170m3 of water 3 After uniform mixing, the initial slump flow and 2h slump expansion were tested to obtain comparison samples SCCA0-1~6 respectively.

[0167] Table 2 Composition of slump flow test samples and comparative samples

[0168]

[0169]

[0170] Test results: The slump flow of test samples SCCA-1 to 9 and control samples SCCA0-1 to 6 are shown in Table 3.

[0171] Table 3:

[0172]

[0173] It can be seen from the test results in Table 3 that the initial slump expansion in the test samples SCCA-1 to 9 is higher than that in the comparative examples SCCA0-1 to SCCA0-6, and the 2h slump expansion loss in the test samples SCCA-1 to 9 is small, especially the slump flow of the test samples SCCA-3 and SCCA-4 is more prominent, indicating that the admixture prepared by the present invention has an outstanding contribution to improving the workability of concrete. The comparison samples SCCA0-1-SCCA0-3 have smaller slump and larger loss; the data results of SCCA0-1, SCCA-3 and SCCA-7 show that the introduction of branched polyether side chains in the molecular side chains can regulate the spatial configuration and stretching degree of concrete admixtures in the concrete multiphase system and improve the slump fluidity; SCCA0-2, SCCA0-3, SCCA0-4 and SCCA-2, SCCA-3, SCCA-7, SCCA-8 introduce carboxylic acid and phosphoric acid groups and hydrolyzable cross-linking monomers in the main chain of the molecule, which can improve the lubrication effect and hydrophilic state of the concrete, improve the slump retention of the concrete mixture and reduce the time loss of the concrete; the above experiments The experimental results show that not using unsaturated phosphoric acid monomers, introducing branched polyethers and introducing unsaturated hydrolyzable cross-linking monomers in admixtures have a greater impact on the workability of concrete; the experimental results of SCCA0-6 show that when the molecular weight of the prepared water reducer is too large, the molecule presents a curled conformation in cement, so that the phosphoric acid and carboxylic acid groups in the molecular structure cannot fully contact with the cement particles, or due to the embedding effect of the molecules, it takes a long time for the hydrolyzable cross-linking structure to hydrolyze, so the corresponding samples have poor dispersion effect when used, and the slump retention ability is also reduced; and the experimental data of SCCA0-5 show that the preparation method of the water reducer provided by the present invention has better slump fluidity than the water reducer prepared by the traditional one-pot method.

[0174] Test 2: Compressive strength test

[0175] Test method:

[0176] 1. Preparation of test samples: 0.35t of PO 42.5 cement and 0.10t of grade II fly ash were used to prepare 8.1kg of the corresponding admixtures in Examples 1-9, and 0.54m of medium sand was added. 3, the particle size is 4.75mm-31.5mm, the stone is 0.594m 3 , add 0.170m3 of water 3 , and formed 100mm×100mm×100mm concrete specimens, removed the molds after standing at room temperature for one day, and cured in a standard curing room to various ages to obtain test samples SCCA-1~9.

[0177] 2. Preparation of control sample: 8.1 kg of the corresponding admixtures in Comparative Examples 1-6 were prepared using 0.35 t of PO 42.5 cement and 0.10 t of Class II fly ash, and then 0.54 m of medium sand was added. 3 , the particle size is 4.75mm-31.5mm, the stone is 0.594m 3 , add 0.170m3 of water 3 The molding and curing methods are the same as those of the test samples, and comparative samples SCCA0-1 to 6 are obtained.

[0178] Test results: The compressive strength of test samples SCCA-1~9 and comparison samples SCCA0-1~6 are shown in Table 4.

[0179] Table 4:

[0180]

[0181]

[0182] As can be seen from Table 4, the compressive strength of Examples SCCA-1 to 9 is good, indicating that the prepared self-compacting concrete admixture can form a good connection with other components in the concrete, can be fully mixed under the action of the concrete's own gravity, form a stable and uniform body, increase the self-compactness of the concrete, and improve the compressive strength of the concrete after solidification. From a microscopic perspective, due to the introduction of branched polyether side chains in the molecular side chains, the spatial configuration and stretching degree of the concrete admixture in the concrete multiphase system can be regulated; the introduction of carboxylic acid and phosphoric acid groups can effectively adsorb on the cement surface, improve the dispersion effect of the concrete, improve the collapse resistance of the concrete mixture, and reduce the time loss of the concrete; the hydrolyzable cross-linking monomer can hydrolyze the ester bond in the molecule in the strongly alkaline concrete environment, which can improve the lubrication effect and hydrophilic state of the concrete. Through the combined action of the above factors, the concrete can be made uniform and stable, so that it has good mechanical properties after hardening. In the comparative example, the above-mentioned branched polyether or phosphoric acid group or hydrolyzable cross-linking monomer is lacking, and its mechanical properties are not as good as those of the prepared product; at the same time, the prepared sample has good performance in the molecular weight range of 60000-80000. When the molecular weight is too high, the molecule presents a curled conformation in cement or concrete, so that the phosphoric acid and carboxylic acid groups in the molecular structure cannot fully contact with the cement particles, or due to the embedding effect of the molecules, it takes a long time for the hydrolyzable cross-linking structure to hydrolyze, so the corresponding sample has a poor dispersion effect when used, thereby affecting the final mechanical properties.

[0183] After being added, the water reducing agent of the present invention can make the concrete mixture have high fluidity, high anti-separation property, high filling property and high gap passing ability.

[0184] Test 3: Water seepage resistance test

[0185] Test method: The test sample groups SCCA-1 to 9 and the comparative sample groups SCCA0-1 to 5 were obtained by the method in test 2, and cylindrical specimens with a top diameter of 175 mm, a bottom diameter of 185 mm, and a height of 150 mm were made. Six corresponding specimens were prepared for each test sample group SCCA-1 to 9 and the comparative sample group SCCA0-1 to 5, and after curing for 28 days, the surfaces of the test samples SCCA-1 to 9 and the comparative samples SCCA0-1 to 5 were cleaned, and a layer of melted sealing material was rolled on the sides of the test sample groups SCCA-1 to 9 and the comparative samples SCCA0-1 to 5, and then the test samples were placed in the impermeability tester according to the standard impermeability test. The water pressure of the test started from 0.2Mpa, and the water pressure was increased by 0.025Mpa every 2h, and the water seepage of the end face of the specimen was recorded at any time, until water seepage was found on the surface of 3 specimens in each group of all samples, and the water pressure at this time was recorded.

[0186] Test results: The maximum water pressure that the test samples SCCA-1 to 9 and the comparative samples SCCA0-1 to 5 can withstand is shown in Table 5.

[0187] Table 5:

[0188]

[0189] It can be seen from Table 5 that the maximum water pressure that the test samples SCCA-1 to 9 can withstand is relatively high, especially the maximum water pressure of the test samples SCCA-1, SCCA-4, SCCA-8 and SCCA-9 is more prominent, while the maximum water pressure that the comparison samples SCCA0-4, SCCA0-5 and SCCA0-6 can withstand is relatively low, indicating that when the amount of water reducer is insufficient, the poor workability of concrete will reduce its density and impermeability, and if the admixture is not fully mixed during the production process, the performance of the admixture in concrete will also be greatly reduced.

[0190] Since the embodiments introduce phosphate monomers, branched polyether structures and hydrolyzable cross-linked monomers, under the combined effect of these factors, the water reducer molecules and cement particles are fully in contact, and the generated gas can escape to a large extent, so that the concrete is evenly dispersed, the porosity of the concrete after hardening is reduced, and the impermeability of the concrete is improved; while in the comparative example, when the above structure is lacking, there are more voids in the concrete and the water impermeability is reduced.

[0191] Conclusion: The highly robust self-compacting concrete-specific phosphate-based water reducer of the present invention can make the concrete mixture have high fluidity, high resistance to separation, high filling and high gap passing capacity after being added; the hardened concrete has excellent mechanical properties and durability, and the compressive strength reaches more than 50Mpa.

[0192] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A phosphate-based water reducer for highly robust self-compacting concrete, characterized by: The phosphoric acid-based water reducer for highly robust self-compacting concrete is obtained by free radical copolymerization of unsaturated phosphoric acid monomer, unsaturated carboxylic acid monomer, unsaturated branched polyether and unsaturated cross-linking monomer; the molar ratio of the unsaturated branched polyether, unsaturated phosphoric acid monomer, unsaturated carboxylic acid monomer and unsaturated cross-linking monomer is 1:(1-5):(2-4):(0.1-0.5); the weight average molecular weight of the phosphoric acid-based water reducer for highly robust self-compacting concrete is 60000-80000; the structure of the unsaturated branched polyether monomer is shown in general formula (1) and general formula (2): Wherein, R1 is H or CH3; R2 is C n H 2n , n is a positive integer of 2 to 10; x1, x2, x3, x4 are positive integers in the range of 10 to 100 and are independent of each other; y1, y2, y3, y4 are positive integers in the range of 1 to 10 and are independent of each other; The weight average molecular weight of the unsaturated branched polyether monomer is 500-5000; The unsaturated carboxylic acid monomer structure is shown in the general formula (3): wherein R3 is H or COOM; R4 is H, CH3 or CH2COOM; and when R3 is COOM, R4 is H; M is any one of a hydrogen atom, an alkali metal ion, an alkaline earth metal ion, an ammonium ion or an organic amine group; The unsaturated phosphoric acid monomer has the general structural formula (4) shown below: X=C n H 2n COO-C n H 2n CO-NH-C n H 2n (4) Where R5 is H or CH3; when X is C n H 2n When n is a positive integer in the range of 1 to 18; when X is COO-C n H 2n Or when X is CO-NH-C n H 2n When n is a positive integer in the range of 1 to 10; The unsaturated cross-linking monomer is a polyethylene glycol acrylate compound, and the weight average molecular weight of the unsaturated cross-linking monomer is 500-1000.

2. The highly robust phosphate-based water reducer for self-compacting concrete according to claim 1, characterized in that: The unsaturated branched polyether is prepared by the following steps: (a) preparation of the initiator: placing an unsaturated alcohol and a catalyst in a reaction container, dripping glycidol into the container, and after the dripping and reaction are completed, removing excess glycidol by vacuum distillation to obtain the initiator; (b) preparation of the unsaturated branched polyether: reacting the initiator with an epoxy compound in the presence of a catalyst, cooling, degassing, and discharging to obtain the unsaturated branched polyether.

3. A phosphate-based water reducer for highly robust self-compacting concrete according to claim 2, characterized in that: In the step (a), the glycidol is added dropwise for 1-2 hours; after the addition is completed, the reaction is carried out at 40-60° C. for 2-5 hours; in the step (a), the molar ratio of the unsaturated alcohol to the glycidol is 1:(1.0-1.1); in the step (a), the catalyst is any one of metallic sodium, metallic potassium, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium hydroxide, potassium hydroxide, sodium hydride and potassium hydride; the mass of the catalyst in the step (a) is 0.1%-0.5% of the mass of the unsaturated alcohol.

4. The phosphate-based water reducer for high robustness self-compacting concrete according to claim 2, characterized in that: In the step (b), nitrogen replacement is first carried out before the reaction, the reaction temperature is 80-120° C., the reaction pressure is ≤-0.07 MPa, and the reaction time is 0.5-1h; in the step (b), the epoxide compound is a mixture of ethylene oxide and propylene oxide, and the molar ratio of the initiator, propylene oxide and ethylene oxide is 1: (1.0-5.0): (15.0-70.0); in the step (b), the catalyst is any one of metallic sodium, metallic potassium, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium hydroxide, potassium hydroxide, sodium hydride and potassium hydride; and the amount of the catalyst used in the step (b) is 0.1%-0.5% of the mass of the initiator.

5. The phosphate-based water reducer for highly robust self-compacting concrete according to claim 1, characterized in that: The unsaturated phosphoric acid monomer is selected from any one of 2-acryloxyethyl phosphate, 2-acryloxypropyl phosphate, 2-methacryloxyethyl phosphate, 2-methacryloxypropyl phosphate, 2-acrylamidoethyl phosphate, 2-acrylamidopropyl phosphate, 2-acrylamidobutyl phosphate, 2-methacrylamidoethyl phosphate, 2-methacrylamidopropyl phosphate, and 2-methacrylamidobutyl phosphate; and the unsaturated cross-linking monomer is selected from any one of polyethylene glycol diacrylate and polyethylene glycol dimethacrylate.

6. A method for preparing a highly robust phosphate-based water reducer for self-compacting concrete according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: (1) preparing a base material: adding an unsaturated branched polyether and water into a reactor, stirring at room temperature to completely dissolve the unsaturated branched polyether, and obtaining a base material; (2) preparing a drop liquid A: adding a reducing agent and a chain transfer agent into water, stirring evenly, and obtaining a drop liquid A; (3) preparing a drop liquid B: adding an unsaturated carboxylic acid monomer and an unsaturated phosphoric acid monomer into water, stirring evenly, and obtaining a drop liquid B; (4) preparing a drop liquid C: adding an unsaturated cross-linking monomer into water, stirring evenly, and obtaining a drop liquid C; (5) adding the oxidant to the base material and stirring for 5-10 minutes, then adding the dropping liquid A, the dropping liquid B and the dropping liquid C to the reactor in sequence at a reaction temperature of 40-60°C, and continuing to keep warm for (1.0-2.0) hours after the addition; (6) after the reaction is completed, neutralizing with an alkaline solution with a mass fraction of 20%-75% to a pH value of 5.0-7.0, cooling to room temperature, and then adding water to prepare a solution to obtain a phosphate-based water reducer specially used for highly robust self-compacting concrete.

7. The method for preparing a highly robust phosphate-based water reducer for self-compacting concrete according to claim 6, characterized in that: In the step (5), the dropping time of the droplet A is (4.0-4.5) h, the dropping time of the droplet B is (3.0-4.0) h, and the dropping time of the droplet C is (4.0-4.5) h.

8. The method for preparing a highly robust phosphate-based water reducer for self-compacting concrete according to claim 6, characterized in that: The alkaline solution in step (6) is an aqueous solution of a hydroxide of a positive monovalent or positive divalent metal or a carbonate thereof; the solid content of the highly robust self-compacting concrete-specific phosphate-based water reducer obtained in step (6) is 25%-50%.

9. The method for preparing a highly robust phosphate-based water reducer for self-compacting concrete according to claim 6, characterized in that: The reducing agent is one of ascorbic acid and sodium bisulfite; the oxidizing agent is any one of hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate; the total mass of the reducing agent and the oxidizing agent is 0.5%-5.0% of the total mass of all unsaturated monomers, and the mass ratio of the reducing agent to the oxidizing agent is (1.0-1.2):1; the chain transfer agent is any one of mercaptoethanol, thioglycolic acid, 2-mercaptopropionic acid and 3-mercaptopropionic acid; the amount of the chain transfer agent is 0.5%-5.0% of the total mass of all unsaturated monomers.

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