阅读说明：本技术 一种增强型混凝土用抗泥外加剂及其制备方法 (Anti-mud additive for reinforced concrete and preparation method thereof ) 是由 高育欣 杨文� 曾超 王福涛 王军 刘明 毕耀 刘其彬 张磊 叶子 罗杰 于 2020-05-14 设计创作，主要内容包括：本发明公开了一种增强型混凝土用抗泥外加剂及其制备方法,该外加剂以水溶性烷基硅醇盐、环氧氯丙烷和含仲胺结构的水溶性有机胺为主要原料,在催化剂作用下,依次进行开环加聚反应制得的端烷基硅醇盐结构阳离子聚合物。其中有机胺与环氧氯丙烷的摩尔比为1:1.1～1:1.5,烷基硅醇盐摩尔数占有机胺与环氧氯丙烷总物质的量的2％～10％,催化剂用量为原料总质量的0.2％～1.5％。本发明所述增强型混凝土用抗泥外加剂对蒙脱土的水化膨胀具有明显抑制效果,不仅能改善含泥骨料新拌混凝土的工作性能,而且能有效提高硬化混凝土的力学强度。(The invention discloses a mud-resistant additive for reinforced concrete and a preparation method thereof. Wherein the molar ratio of the organic amine to the epoxy chloropropane is 1: 1.1-1: 1.5, the mole number of the alkyl silicon alkoxide accounts for 2-10% of the total mass of the organic amine and the epoxy chloropropane, and the dosage of the catalyst is 0.2-1.5% of the total mass of the raw materials. The mud-resistant additive for the reinforced concrete has an obvious effect of inhibiting hydration expansion of montmorillonite, can improve the working performance of fresh concrete containing mud aggregate, and can effectively improve the mechanical strength of hardened concrete.)

1. The mud-resistant additive for the reinforced concrete is characterized in that the additive is prepared by taking water-soluble alkyl silicon alkoxide, epoxy chloropropane and organic amine as raw materials and performing ring-opening addition polymerization under the action of a catalyst; the molecular structural formula of the mud-resistant additive is as follows:

in the formula, R₁Is C1-C6 alkyl, R₂is-OH,-CH₃、-OCH₃、-CH₂CH₃、-OCH₂CH₃One of (1), R₃is-CH₃、-CH₂CH₃、-CH₂CH₂CH₃、-CH₂CH₂OH、-CH₂CHCH₃And one of OH, n is an integer and takes a value of 5-40.

2. The mud-resistant admixture for reinforced concrete according to claim 1, wherein n is 5 to 25.

3. The mud-resistant admixture for reinforced concrete according to claim 1, wherein said alkylsiliconate is one of potassium methylsiliconate, potassium trimethylsilylate, sodium methylsiliconate, sodium dimethylphenylsiliconate, sodium ethylsiliconate and sodium methyldiethoxysilanolate.

4. The mud-resistant admixture for reinforced concrete according to claim 3, wherein the organic amine is a water-soluble organic amine having a secondary amine structure, and includes one of dimethylamine, diethylamine, dipropylamine, diethanolamine, and isopropanolamine.

5. The mud-resistant additive for reinforced concrete according to claim 4, wherein the molar ratio of the organic amine to the epichlorohydrin is 1: 1.1-1: 1.5, and the amount of the alkyl silanolate is 2-10% of the total amount of the organic amine and the epichlorohydrin.

6. The mud-resistant admixture for reinforced concrete according to claim 5, wherein said catalyst is one of potassium bicarbonate, sodium carbonate, potassium carbonate; the dosage of the catalyst is 0.2-1.5% of the total mass of the alkyl silicon alkoxide, the epoxy chloropropane and the organic amine.

7. The method for preparing a mud resistance admixture for reinforced concrete according to any one of claims 1 to 6, comprising the steps of:

(1) adding alkyl silicon alkoxide, a catalyst and deionized water into a reaction container, uniformly stirring, dropwise adding epoxy chloropropane in an amount equal to that of the alkyl silicon alkoxide within 1-2 hours, reacting at 60-70 ℃ for 4-8 hours, and cooling to room temperature after the reaction is finished to obtain a solution A;

(2) dropwise adding the rest epoxy chloropropane and the rest organic amine into the solution A, finishing dropwise adding within 1.5-2.5 hours, and controlling the reaction temperature to be 30-40 ℃;

(3) after the dropwise addition, heating to 70-80 ℃, continuing to react for 1-4 hours, cooling to room temperature after the reaction is finished, and adding water to dilute to 50% of mass concentration to obtain the anti-mud additive for the reinforced concrete.

8. The method for preparing a mud-resistant admixture for reinforced concrete according to claim 7, wherein in the step (1), the molar concentration of the alkylsiliconate is 5 to 12 mol-L^-1。

Technical Field

The invention relates to the technical field of concrete admixtures, in particular to an enhanced concrete anti-mud admixture and a preparation method thereof.

Background

The polycarboxylate superplasticizer serving as a third-generation high-performance water reducing agent has the characteristics of high water reducing rate and good slump retaining performance. Along with the rapid development of the building industry in China, the consumption of building gravels is huge, high-quality gravels resources are scarce, and particularly in some areas with poor ground quality, the problem that the gravels contain mud becomes a difficult problem to be solved urgently in the concrete industry. A large number of engineering examples and researches show that compared with naphthalene series, melamine series and sulfamic acid series water reducing agents, the polycarboxylic acid water reducing agent (PCE) which is commonly used in the production of concrete at present is more sensitive to the content of mud in aggregate. The main reason is that the Polyoxyethylene (PEO) side chain contained in the PCE molecule is easily embedded into the interlayer of clay mineral, and cannot play a role in steric hindrance, so that the dispersion effect on cement particles is lost, and the concrete slump loss prevention effect is poor due to the fact that the admixture doping amount is increased. In addition, the hydration of clay causes volume expansion, which causes the compaction degree of concrete to be reduced, and leads to the reduction of the mechanical strength of the concrete. At present, in the production of concrete containing mud aggregate, in order to ensure the mechanical strength of hardened concrete, the dosage of cementing materials such as cement is often required to be increased, but the load of the concrete material on the environment and resources is increased. At present, clay contained in construction sand is different according to different components of a production place, but the clay is mainly aluminosilicate minerals with a layered structure, wherein montmorillonite has the largest negative influence on the working performance and the mechanical performance of the concrete containing clay aggregate. The anti-mud functional additive can inhibit the structural design in the aspects of clay expansion, sacrificial agents and the like, reduces the consumption of PCE, and improves the working performance of the mud-containing aggregate concrete.

Disclosure of Invention

The invention aims to provide a preparation method of an enhanced concrete mud-resistant additive which has the functions of improving the fluidity, the retentivity and the mechanical strength of concrete containing mud aggregates.

The mud-resistant additive for reinforced concrete provided by the invention is prepared by taking water-soluble alkyl silicon alkoxide, epoxy chloropropane and organic amine as raw materials and performing ring-opening addition polymerization under the action of a catalyst.

The molar ratio of the organic amine to the epoxy chloropropane is 1: 1.1-1: 1.5, and the dosage of the alkyl silicon alkoxide is 2-10% of the total amount of the organic amine and the epoxy chloropropane. The dosage of the catalyst is 0.2-1.5% of the total mass of the alkyl silicon alkoxide, the epoxy chloropropane and the organic amine.

The preparation method comprises the following steps:

(1) adding alkyl silicon alkoxide, a catalyst and deionized water into a reaction container, uniformly stirring, dropwise adding epoxy chloropropane in an amount equal to that of the alkyl silicon alkoxide within 1-2 hours, reacting at 60-70 ℃ for 4-8 hours, and cooling to room temperature after the reaction is finished to obtain a solution A; the molar concentration of the alkyl silicon alkoxide in the deionized water is 5-12 mol.L^-1. The reaction is violent when the concentration of the alkyl silicon alkoxide is too high, the reaction is not easy to control, the concentration is too low, the reaction is insufficient, and the conversion rate is low. The catalyst is one of potassium bicarbonate, sodium carbonate and potassium carbonate.

(2) And (3) dropwise adding the residual epoxy chloropropane and organic amine into the solution A, finishing dropwise adding within 1.5-2.5 hours, and controlling the reaction temperature to be 30-40 ℃.

(3) After the dropwise addition, heating to 70-80 ℃, continuing to react for 1-4 hours, cooling to room temperature after the reaction is finished, and adding water to dilute to 50% of mass concentration to obtain the anti-mud additive for the reinforced concrete.

The chemical reaction processes involved in the preparation method are as follows in sequence:

the alkyl silicon alkoxide is selected from one of methyl silicon alkoxide potassium, trimethyl silicon alkoxide, methyl silicon alkoxide sodium, dimethyl phenyl silicon alkoxide sodium, ethyl silicon alkoxide sodium and methyl diethoxy silicon alkoxide sodium. The organic amine is selected from water-soluble organic amine containing secondary amine structure, preferably one of dimethylamine, diethylamine, dipropylamine, diethanolamine and iso-dipropanolamine.

Compared with the prior art, the invention has the advantages that:

(1) the invention utilizes alkyl silicon alkoxide to react with epoxy chloropropane to prepare methyl silicic acid glycidyl ether, and then the methyl silicic acid glycidyl ether reacts with water-soluble organic amine containing a secondary amine structure to prepare the cationic polymer with an alkyl-terminated silicon alkoxide structure. The soluble alkyl silicon alkoxide is combined with the cation chain segment, the alkyl silicon alkoxide structure can form a hydrophobic layer on a clay interface to prevent the clay from adsorbing moisture and a water reducing agent, and meanwhile, the hydrolyzed silanol can form a chemical bond with the surface of a hydration product of a cementing material, so that the interaction force between the interfaces is enhanced, and the effects of improving the working performance and the strength of concrete are achieved.

(2) The cationic polymer chain segment can effectively inhibit clay expansion, reduce the adsorption of clay layers to the water reducing agent, increase the compaction degree of hardened concrete and improve the strength of the concrete.

(3) The mud-resistant admixture has the functions of improving the fluidity, the slump resistance and the mechanical strength of the concrete containing mud aggregates, and can effectively improve the negative effects of the mud content of the aggregates on the working performance and the mechanical performance of the concrete.

(4) The raw materials related by the invention are cheap and easy to obtain, the synthesis process is simple and convenient, no additional reaction solvent is required to be added, and the method is environment-friendly and suitable for popularization and application.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is an XRD diagram of the interlayer spacing of montmorillonite in water, water reducing agent solution and water reducing agent + anti-mud additive solution.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.