阅读说明：本技术 一种高铁专用改性混凝土外加剂及其制备方法 (Modified concrete additive special for high-speed rail and preparation method thereof ) 是由 王亚军 卢祎 于 2020-05-29 设计创作，主要内容包括：一种高铁专用改性混凝土外加剂及其制备方法,包括高效减水剂60-84份、聚丙烯纤维0.2-0.6份和吸水树脂1-3.5份；高效减水剂是在引发剂、链转移剂和还原剂存在条件下,以丙烯酸、不饱和聚氧乙烯醚和3-烯丙氧基-2-磺酸氢丙酯-1-丙磺酸钠盐为共聚单体共聚反应而成；本发明提供的外加剂包括3-烯丙氧基-2-磺酸氢丙酯-1-丙磺酸钠盐,是通过将3-烯丙氧基-2-羟基-1-丙磺酸钠盐的醇羟基与氯磺酸反应,引入亲水性磺酸基,使得共聚单体具有较高密度带有负电荷的磺酸基,与水泥中的正电离子(Ca<Sup>2+</Sup>)之间产生静电斥力,水泥颗粒间和被包裹在空间网状结构中的水分子得以释放出来,从而使减水效果提升。(A modified concrete admixture special for high-speed rail and a preparation method thereof, comprising 60-84 parts of high-efficiency water reducing agent, 0.2-0.6 part of polypropylene fiber and 1-3.5 parts of water-absorbing resin; the high-efficiency water reducing agent is prepared by taking acrylic acid, unsaturated polyoxyethylene ether and 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt as raw materials under the condition of existence of an initiator, a chain transfer agent and a reducing agentCopolymerization of comonomers; the additive provided by the invention comprises 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt, and hydrophilic sulfonic acid groups are introduced by reacting alcoholic hydroxyl groups of the 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt with chlorosulfonic acid, so that a comonomer has a higher density of sulfonic groups with negative charges and positive ions (Ca) in cement 2+ ) Electrostatic repulsion is generated between the cement particles, and water molecules among the cement particles and wrapped in the space net structure are released, so that the water reducing effect is improved.)

1. The special modified concrete admixture for the high-speed rail is characterized by comprising 60-84 parts of a high-efficiency water reducing agent, 0.2-0.6 part of polypropylene fiber and 1-3.5 parts of water-absorbing resin;

the high-efficiency water reducing agent is prepared by copolymerization reaction of acrylic acid, unsaturated polyoxyethylene ether and 3-allyloxy-2-hydrogen propyl sulfonate-1-propane sulfonic acid sodium salt serving as comonomers in the presence of an initiator, a chain transfer agent and a reducing agent; wherein the mass component ratio of acrylic acid, unsaturated polyoxyethylene ether, 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt, initiator, chain transfer agent and reducing agent is 1: (0.2-0.35): (0.12-0.2): (0.003-0.03): (0.006-0.01): (0.001-0.01).

2. The special modified concrete admixture for high-speed rail according to claim 1, wherein the preparation method of the high-efficiency water reducing agent comprises the following steps:

(1) preparation of 3-allyloxy-2-hydrocapropyl sulfonate-1-propanesulfonic acid sodium salt: 1) under the condition of ice-water bath, dripping chlorosulfonic acid into anhydrous pyridine according to a certain proportion to obtain an esterification reagent; 2) adding 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt into an esterification reagent, reacting for 1-3h at 0-6 ℃, and removing pyridine by rotary evaporation and concentration to obtain the 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt;

(2) taking materials according to the mass ratio, and dissolving an initiator, a chain transfer agent and a reducing agent in water to serve as first drop of liquid; dissolving acrylic acid in water to prepare second dropping liquid with mass concentration of 55-65%;

(3) adding unsaturated polyoxyethylene ether, 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt and deionized water into a reaction kettle according to the mass ratio to prepare a mixed solution with the mass concentration of 3-6.8%, stirring and heating to 50-65 ℃, after the materials are dissolved, simultaneously adding a first dropping liquid and a second dropping liquid into the reaction kettle, and reacting for 3-5 hours at 80-100 ℃ after the dropping is finished;

(4) and after the reaction is finished, adjusting the pH value of the material to 7-9 to obtain the high-efficiency water reducing agent.

3. The special modified concrete admixture for high-speed rail according to claim 1, wherein the polypropylene fiber has a fiber diameter of 15-30 μm and a length of 10-20 mm.

4. The special modified concrete admixture for high-speed rail according to claim 1, wherein the water-absorbent resin is polyacrylic resin or acrylamide-acrylic acid copolymer.

5. The special modified concrete admixture for high-speed rails according to claim 1, wherein the initiator is at least one of ammonium persulfate or potassium persulfate.

6. The special modified concrete admixture for high-speed rail according to claim 1, wherein the chain transfer agent is at least one of dodecyl mercaptan or thioglycolic acid.

7. The special modified concrete admixture for high-speed rail according to claim 1, wherein the reducing agent is at least one of vitamin C or vitamin E.

8. The preparation method of the special modified concrete admixture for high-speed rail according to claim 1, which is characterized by comprising the following steps: the method comprises the following steps:

(1) grinding the water-absorbing resin, and controlling the particle size of the water-absorbing resin to be 50-400 nm;

(2) and respectively weighing and mixing a high-efficiency water reducing agent, polypropylene fibers and water-absorbent resin according to the parts of the raw materials to obtain the special modified concrete admixture for the high-speed rail.

Technical Field

The invention belongs to the field of concrete admixtures, and particularly relates to a modified concrete admixture special for high-speed rails and a preparation method thereof.

Background

In the existing high-speed rail construction in China, concrete construction occupies a large proportion, and along with the rapid development of high-speed railway business and high-standard requirements on high-speed railways, the demand of high-performance concrete for the high-speed railways is more and more increased; concrete is a general term for engineering composite materials in which aggregate is cemented into a whole by a cementing material. The concrete is usually cement as cementing material and sand and stone as aggregate; mixing with water (containing additive or admixture) according to a certain proportion, and stirring to obtain the cement concrete, also called as common concrete;

because the concrete is subjected to capillary negative pressure in the hardening process of the cement, water absorbed by capillary pores and gel pores is lost, the relative humidity is reduced or CO in the air is mixed with the concrete₂A reaction accompanied by volume shrinkage and finally causing plastic shrinkage, drying shrinkage, self-shrinkage, carbonization shrinkage, and the like of concrete, thereby causing a decrease in durability of concrete; therefore, the quality of the concrete has great influence on the quality of the structure, and particularly in the construction of high-speed railways taking safety as a primary index, the high-performance concrete is more important and takes place at the right moment; the high-performance concrete is prepared by adopting a modern concrete technology on the basis of greatly improving the performance of common concrete, and takes durability, high strength and low shrinkage as design indexes; among them, the admixture added to concrete is an important component for imparting high performance to the concrete, and among various concrete admixtures, a high efficiency water reducing agent which is representative of a hydraulic mixture having a fluidizing effect, an early strength agent which accelerates development of early strength of concrete, and the like, although they have good effects, each of these individual admixtures has advantages and disadvantages, and cannot intensively solve the problems of high compressive strength required for high performance concrete and control of shrinkage of concrete.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provides a modified concrete admixture special for high-speed rail, which comprises 60-84 parts of a high-efficiency water reducing agent, 0.2-0.6 part of polypropylene fiber and 1-3.5 parts of water-absorbing resin;

the high-efficiency water reducing agent is prepared by copolymerization reaction of acrylic acid, unsaturated polyoxyethylene ether and 3-allyloxy-2-hydrogen propyl sulfonate-1-propane sulfonic acid sodium salt serving as comonomers in the presence of an initiator, a chain transfer agent and a reducing agent; wherein the mass component ratio of acrylic acid, unsaturated polyoxyethylene ether, 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt, initiator, chain transfer agent and reducing agent is 1: (0.2-0.35): (0.12-0.2): (0.003-0.03): (0.006-0.01): (0.001-0.01); the specific reaction process is as follows:

preferably, the preparation method of the high efficiency water reducing agent comprises the following steps:

(1) preparation of 3-allyloxy-2-hydrocapropyl sulfonate-1-propanesulfonic acid sodium salt: 1) under the condition of ice-water bath, dripping chlorosulfonic acid into anhydrous pyridine according to a certain proportion to obtain an esterification reagent; 2) adding 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt into an esterification reagent, reacting for 1-3h at 0-6 ℃, and removing pyridine by rotary evaporation and concentration to obtain the 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt; the specific reaction process is as follows:

(2) taking materials according to the mass ratio, and dissolving an initiator, a chain transfer agent and a reducing agent in water to serve as first drop of liquid; dissolving acrylic acid in water to prepare second dropping liquid with mass concentration of 55-65%;

(3) adding unsaturated polyoxyethylene ether, 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt and deionized water into a reaction kettle according to the mass ratio to prepare a mixed solution with the mass concentration of 3-6.8%, stirring and heating to 50-65 ℃, after the materials are dissolved, simultaneously adding a first dropping liquid and a second dropping liquid into the reaction kettle, and reacting for 3-5 hours at 80-100 ℃ after the dropping is finished;

(4) and after the reaction is finished, adjusting the pH value of the material to 7-9 to obtain the high-efficiency water reducing agent.

Preferably, the polypropylene fiber has a fiber diameter of 15 to 30 μm and a length of 10 to 20 mm.

Preferably, the water-absorbing resin is polyacrylic resin or acrylamide-acrylic acid copolymer.

Preferably, the initiator is at least one of ammonium persulfate or potassium persulfate.

Preferably, the chain transfer agent is at least one of dodecyl mercaptan or thioglycolic acid.

Preferably, the reducing agent is at least one of vitamin C or vitamin E.

A preparation method of a special modified concrete admixture for high-speed rail comprises the following steps:

(1) grinding the water-absorbing resin, and controlling the particle size of the water-absorbing resin to be 50-400 nm;

(2) and respectively weighing and mixing a high-efficiency water reducing agent, polypropylene fibers and water-absorbent resin according to the parts of the raw materials to obtain the special modified concrete admixture for the high-speed rail.

The invention has the following beneficial effects:

(1) the high-efficiency water reducing agent in the admixture comprises 3-allyloxy-2-hydrogen propyl sulfonate-1-propanesulfonic acid sodium salt, wherein the alcoholic hydroxyl of the 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt is reacted with chlorosulfonic acid to introduce hydrophilic sulfonic acid groups, so that a comonomer has sulfonic acid groups with higher density and negative charges, and the groups with the negative charges can be reacted with positive ions (Ca) in cement²⁺) The electrostatic interaction is generated between the two groups, and the electrostatic interaction can anchor the groups on the cement surface to form electric double layer distribution; thus, by the generated electrostatic repulsion, water molecules among cement particles and wrapped in the space net structure are released, so that the water reducing effect is improved, the water-cement ratio is reduced, the porosity is reduced, the pore diameter is refined, and the shrinkage of a hardened body is reduced;

(2) the high-efficiency water reducing agent is synthesized through free radical copolymerization, the process is simple and environment-friendly, the polypropylene fiber is introduced, the compressive strength of the concrete is improved, and the high-efficiency water reducing agent plays a vital role in controlling the shrinkage of the concrete; the water-absorbing resin is added, so that unreacted water in the concrete can be fully present in capillary pores within a long time, the generation of capillary pressure is avoided, and the shrinkage cracking of the concrete is reduced.

Detailed Description

For the purpose of enhancing understanding of the present invention, the present invention will be further described in detail with reference to the following examples, which are provided for illustration only and are not to be construed as limiting the scope of the present invention.