阅读说明：本技术 一种低引气缓凝型聚羧酸减水剂及其制备方法 (Low-air-entraining slow-setting type polycarboxylate superplasticizer and preparation method thereof ) 是由 孙洪彬 于 2020-03-26 设计创作，主要内容包括：本发明公开了一种低引气缓凝型聚羧酸减水剂,按质量份数组成分别是：大单体0.5～1.2份,丙烯酸0.1～0.3份,甲基丙烯磺酸钠0.05～0.2份,2-羟乙基甲基丙烯酸酯磷酸酯0.01～0.035份,硅烷改性石墨烯0.002～0.005份,过硫酸铵0.00015～0.0002份,中和剂为0.0001～0.0002份,水3～6份,本低引气缓凝型聚羧酸减水剂,可以在较小的掺量下具有较好的分散性,保塑性好,减水率高,有效的减少气体引入,同时兼具更好的缓凝效果。由于加入了硅烷改性石墨烯,反应过程中,各成分之间的结合效果更好,反应后各分子相互之间的间隙更小,从而使含气量更低。(The invention discloses a low-air-entraining retarding polycarboxylic acid water reducing agent which comprises the following components in parts by mass: 0.5-1.2 parts of macromonomer, 0.1-0.3 part of acrylic acid, 0.05-0.2 part of sodium methallyl sulfonate, 0.01-0.035 part of 2-hydroxyethyl methacrylate phosphate, 0.002-0.005 part of silane modified graphene, 0.00015-0.0002 part of ammonium persulfate, 0.0001-0.0002 part of neutralizer and 3-6 parts of water. Due to the addition of the silane modified graphene, the combination effect of the components is better in the reaction process, and the gaps among the molecules after the reaction are smaller, so that the gas content is lower.)

1. The low-air-entraining retarding polycarboxylate superplasticizer is characterized by comprising the following components in parts by mass: 0.5-1.2 parts of macromonomer, 0.1-0.3 part of acrylic acid, 0.05-0.2 part of sodium methallyl sulfonate, 0.01-0.035 part of 2-hydroxyethyl methacrylate phosphate, 0.002-0.005 part of silane modified graphene, 0.00015-0.0002 part of ammonium persulfate, 0.0001-0.0002 part of neutralizer and 3-6 parts of water.

2. The low-air-entraining retarding polycarboxylate superplasticizer according to claim 1, wherein the raw materials in the formula comprise the following components in parts by mass: 1 part of macromonomer, 0.235 part of acrylic acid, 0.1 part of sodium methallyl sulfonate, 0.027 part of 2-hydroxyethyl methacrylate phosphate, 0.0035 part of silane modified graphene, 0.0002 part of ammonium persulfate, 0.00015 part of neutralizer and 5 parts of water.

3. The low-bleed air retarding polycarboxylate water reducer according to claim 1 or 2, characterized in that said macromonomer consists of isopentenyl, polyoxyethylene and polyoxypropylene ether.

4. The preparation method of the low-air-entraining retarding polycarboxylate superplasticizer according to claim 1, characterized by comprising the following steps:

step 1: extracting the raw materials according to the proportion, dissolving a macromonomer in water to obtain an aqueous solution A, dissolving acrylic acid, sodium methallyl sulfonate, 2-hydroxyethyl methacrylate phosphate and silane modified graphene in water to obtain an aqueous solution B, and dissolving ammonium persulfate in water to obtain an aqueous solution C;

step 2: sequentially adding the aqueous solution A, the aqueous solution B and the aqueous solution C into a container, heating to 75-85 ℃, and then continuously stirring for 6-7 hours;

and step 3: and after stirring, cooling to 30-40 ℃, adding a neutralizer to adjust the pH of the solution to 5, and obtaining the low-air-entraining slow-setting polycarboxylic acid water reducer.

5. The preparation method of the low-air-entraining retarding polycarboxylate superplasticizer according to claim 4, wherein the temperature rise in the step 2 is 80 ℃ and the stirring time is 6 hours.

6. The preparation method of the low-air-entraining retarding polycarboxylate superplasticizer according to claim 4, characterized in that the neutralizing agent is a sodium hydroxide solution with a mass concentration of 25%.

7. The preparation method of the low-air-entraining retarding polycarboxylate superplasticizer according to claim 4, wherein the preparation method of the silane-modified graphene comprises the following steps: pre-dispersing 40-70 parts of redox graphene powder and 5-8 parts of sodium dodecyl benzene sulfonate in 500 parts of ethanol; then adding 1-3 parts of silane coupling agent, 2-3 parts of active calcium phosphate and 0.1-0.3 part of polyethylene glycol 1000 to modify and disperse graphene, and shearing and stirring at a high speed of 6000-7500 r/min for 1.5-2.5 h; and filtering and drying after modification to obtain the silane modified graphene.

8. The preparation method of the low-air-entraining retarding polycarboxylic acid water reducer according to claim 7, characterized in that the mass ratio of the redox graphene powder to the silane coupling agent is (20-40): 1.

Technical Field

The invention relates to the technical field of concrete admixtures, in particular to a low-air-entraining retarding polycarboxylic acid water reducer and a preparation method thereof.

Background

In engineering application, a polycarboxylate water reducer can generate excessive air entraining amount, so that the phenomena of excessive air content in concrete and reduction of concrete hardening strength are caused, the conventional method is to compound the polycarboxylate water reducer with a defoaming agent to reduce the air content in the concrete and improve the influence of the polycarboxylate water reducer on the concrete hardening strength, but the effect is not ideal, meanwhile, the polycarboxylate water reducer has weak retarding effect, a retarder and the polycarboxylate water reducer are usually compounded in engineering, although the retarding effect can be achieved, the setting time is often too short or too long due to the influence of certain reasons, and the concrete is greatly influenced.

Chinese invention patent CN108192040A discloses a preparation method of a low-air-entraining type solid polycarboxylic acid water reducing agent, which adopts an amidation method to introduce a benzene ring and an amide group with a rigid structure and a polyether amine structure of ethylene oxide/propylene oxide with a defoaming structure, so that the finally synthesized water reducing agent has good water reducing, slump retaining and low-air-entraining effects, and the durability of concrete is effectively enhanced; the microwave heating method is adopted, the heating speed is high, the operation is simple, the automatic control precision is high, and the cleaning and pollution-free effects are realized. Chinese patent CN 105111387A discloses a preparation method of a low-air-entraining type solid polycarboxylic acid water reducing agent. The method can adjust the surface tension of the water reducing agent by adjusting the composition of polyether monomers in the polycarboxylic water reducing agent and introducing other hydrophobic groups, so that the water reducing agent molecules have a foam eliminating and controlling effect, and the problem of high gas content in concrete is solved. However, the preparation methods of the two water reducing agents have long preparation time and very complicated process.

Chinese patent CN106883355A discloses a low-air-entraining viscosity-reducing type polycarboxylate superplasticizer, which is prepared by polymerizing an alkyl phosphotriester mixture, prenol polyoxyethylene ether and unsaturated carboxylic acid through free radicals under the action of an initiator and a chain transfer agent. According to the method, alkyl phosphate triester monomers containing two double bonds are introduced to the main chain, so that the obtained polycarboxylate water reducer molecules are in a heterocyclic multi-branched structure, the thickness of an adsorption layer of the polycarboxylate water reducer is increased, the plastic viscosity of concrete can be remarkably reduced, and meanwhile, the defoaming performance of the obtained polycarboxylate water reducer can be effectively improved and the air entrainment performance of the polycarboxylate water reducer can be reduced by introducing the phosphate triester structure into the molecular structure of the polycarboxylate water reducer. However, the gas content of the polycarboxylic acid water reducing agent prepared by the method still reaches about 1% when the polycarboxylic acid water reducing agent is applied, so that the process is required to be improved, and the water reducing agent with lower gas content is prepared.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides the low-air-entraining slow-setting polycarboxylate superplasticizer which has the advantages of better dispersibility, good plasticity retention, high water reducing rate, effective reduction of gas introduction, better slow setting effect and capability of effectively solving the problems in the background art.

In order to achieve the purpose, the invention provides the following technical scheme:

the low-air-entraining retarding polycarboxylate superplasticizer comprises the following components in parts by weight: 0.5-1.2 parts of macromonomer, 0.1-0.3 part of acrylic acid, 0.05-0.2 part of sodium methallyl sulfonate, 0.01-0.035 part of 2-hydroxyethyl methacrylate phosphate, 0.002-0.005 part of silane modified graphene, 0.00015-0.0002 part of ammonium persulfate, 0.0001-0.0002 part of neutralizer and 3-6 parts of water.

Preferably, the raw materials in the formula comprise the following components in parts by mass: 1 part of macromonomer, 0.235 part of acrylic acid, 0.1 part of sodium methallyl sulfonate, 0.027 part of 2-hydroxyethyl methacrylate phosphate, 0.0035 part of silane modified graphene, 0.0002 part of ammonium persulfate, 0.00015 part of neutralizer and 5 parts of water.

Preferably, the macromonomer consists of isopentenyl, polyoxyethylene and polyoxypropylene ethers.

The preparation method of the low-air-entraining retarding polycarboxylate superplasticizer comprises the following steps:

step 1: extracting the raw materials according to the proportion, dissolving a macromonomer in water to obtain an aqueous solution A, dissolving acrylic acid, sodium methallyl sulfonate, 2-hydroxyethyl methacrylate phosphate and silane modified graphene in water to obtain an aqueous solution B, and dissolving ammonium persulfate in water to obtain an aqueous solution C;

step 2: sequentially adding the aqueous solution A, the aqueous solution B and the aqueous solution C into a container, heating to 75-85 ℃, and then continuously stirring for 6-7 hours;

and step 3: and after stirring, cooling to 30-40 ℃, adding a neutralizing agent to adjust the pH of the solution to 5, and thus obtaining the low-air-entraining slow-setting polycarboxylic acid water reducer.

Preferably, the temperature rise in the step 2 is 80 ℃, and the stirring time is 6 h.

Preferably, the neutralizing agent is a sodium hydroxide solution with a mass concentration of 25%.

Preferably, the preparation method of the silane-modified graphene comprises the following steps: pre-dispersing 40-70 parts of redox graphene powder and 5-8 parts of sodium dodecyl benzene sulfonate in 500 parts of ethanol; then adding 1-3 parts of silane coupling agent, 2-3 parts of active calcium phosphate and 0.1-0.3 part of polyethylene glycol 1000 to modify and disperse graphene, and shearing and stirring at a high speed of 6000-7500 r/min for 1.5-2.5 h; and filtering and drying after modification to obtain the silane modified graphene.

Preferably, the mass ratio of the redox graphene powder to the silane coupling agent is (20-40): 1.

compared with the prior art, the invention has the beneficial effects that: the low-air-entraining retarding polycarboxylate water reducer adopts a macromonomer consisting of isopentenyl, polyoxyethylene and polyoxypropylene ether, can effectively change the hydrophilicity of polycarboxylic acid, change the surface tension of the polycarboxylic acid and reduce the bubble formation rate, simultaneously selects acrylic acid and sodium methallyl sulfonate as unsaturated carboxylic acid, takes ammonium persulfate as an initiator, polymerizes the acrylic acid and the sodium methallyl sulfonate under the action of the ammonium persulfate, and adds 2-hydroxyethyl methacrylate phosphate to ensure that a polymer has a characteristic active group side chain, thereby having excellent retarding effect; in order to further reduce the gas content, the silane modified graphene is added, and compared with the traditional polycarboxylic acid water reducing agent, the silane modified graphene is added, so that the combination effect of all the components is better in the reaction process, and the gaps among all the molecules after the reaction are smaller, so that the gas content is lower.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.