阅读说明：本技术 一种烯酮类混凝土减胶剂及其制备方法 (Ketene concrete glue reducing agent and preparation method thereof ) 是由 徐锋 于 2020-07-30 设计创作，主要内容包括：本发明公开了一种烯酮类混凝土减胶剂及其制备方法,所述混凝土减胶剂由以下重量百分比的物质组成：二甲基丙烯酸8～25份、烯酮类单体8～20份、乙二醇3～10份、缓凝剂2～8份、引发剂0.5～3份,余量为水。本发明能够使混凝土的工作性能得到改善,具体的,它能使水泥在混凝土中分散的更充分,水泥的利用率更高,从而显著提高混凝土的早期强度和后期强度；另外对混凝土的后期韧性和抗裂性方面也有所改善。正因为此减胶剂同时有提高混凝土强度和抗裂功效,在工程作业中保持混凝土强度不变的前提下,可以减少单位体积混凝土的水泥用量,延长混凝土建筑的使用寿命,从而降低工程造价。(The invention discloses an ketene concrete gel reducing agent and a preparation method thereof, wherein the concrete gel reducing agent consists of the following substances in percentage by weight: 8-25 parts of dimethyl acrylic acid, 8-20 parts of ketene monomers, 3-10 parts of ethylene glycol, 2-8 parts of retarder, 0.5-3 parts of initiator and the balance of water. The invention can improve the working performance of the concrete, in particular, the invention can lead the cement to be more fully dispersed in the concrete and lead the utilization rate of the cement to be higher, thereby obviously improving the early strength and the later strength of the concrete; in addition, the later-period toughness and crack resistance of the concrete are improved. Because the glue reducing agent has the effects of improving the strength and the crack resistance of the concrete, the cement consumption of the concrete in unit volume can be reduced on the premise of keeping the strength of the concrete unchanged in engineering operation, the service life of a concrete building is prolonged, and the construction cost is reduced.)

1. The vinyl ketone concrete gel reducing agent is characterized by comprising the following raw materials in percentage by weight:

2. the vinyl ketone concrete gel reducing agent as claimed in claim 1, wherein the molar ratio of the dimethyl acrylic acid, the vinyl ketone monomer, the ethylene glycol and the initiator is 2-6: 1-4: 0.5-3: 0.1-0.3.

3. The vinyl ketone concrete gel reducing agent as claimed in claim 2, wherein the molar ratio of the dimethyl acrylic acid, the vinyl ketone monomer, the ethylene glycol and the initiator is preferably 3-6: 1.5-3: 0.5-2: 0.1-0.2.

4. The adhesive reducing agent for the ketene concrete according to claim 1, wherein the ketene monomer is prepared by mixing one or more of diethylketene, methylketene, 3, 5-dienone, 4, 5-allene and the like according to any proportion.

5. The enones concrete gel reducer of claim 1, wherein the retarder is a disaccharide compound, and the disaccharide compound comprises lactose, maltose and the like.

6. The ketene concrete gel reducing agent according to claim 5, wherein the retarder is preferably maltose.

7. The vinyl ketone concrete gel reducing agent as claimed in claim 1, wherein the initiator is formed by mixing one or more of ammonium persulfate, potassium persulfate, sodium persulfate and the like according to any proportion.

8. The ketene concrete gel reducing agent according to claim 7, wherein the initiator is preferably ammonium persulfate.

9. The preparation method of the ketene concrete gel reducer of claim 1, which is characterized by comprising the following steps:

(1) and (3) taking materials, and preparing an initiator solution with the mass percentage concentration of 3-8%.

(2) Adding the ketene monomer, the dimethyl acrylic acid and the ethylene glycol into a reflux reaction tank, starting stirring and gradually heating, finally heating to 90-120 ℃, and controlling the heating time to be about 30-40 min.

(3) And (3) after the temperature is raised to 90-120 ℃, beginning to dropwise add the initiator solution prepared in the step (1) into the solution system, controlling the dropwise adding speed to ensure that the dropwise adding time is 2-3 hours, keeping the temperature of the solution system constant all the time in the dropwise adding process, and continuing to perform constant-temperature reaction for about 3-5 hours after the dropwise adding is finished.

(4) Stopping heating, stirring and naturally cooling, adding a retarder and the balance of water when the temperature is reduced to below 60 ℃, adjusting the pH value of the solution to 9-10, stirring at a constant temperature of 35-50 ℃ for about 0.5-1 hour, and finally cooling the solution to room temperature to obtain the concrete gel reducer.

Technical Field

The invention relates to the technical field of concrete admixtures, in particular to an ketene concrete glue reducing agent and a preparation method thereof.

Background

In recent years, the construction industry in China is unprecedentedly developed, and the scale of the building is unprecedented along with the updating and the perfection of infrastructure. Concrete in building materials is widely used in civil engineering construction due to factors such as abundant raw materials, low price, simple production process, wide compression strength grade range and the like. Cement is the main component of concrete, and is a part of the material with the highest cost of concrete. According to a large amount of researches, 10% -15% of cement in the existing concrete is not completely dispersed and hydrated, so that the due effect cannot be fully exerted, and if the hydration rate of the cement can be improved, a large amount of engineering cost can be saved. In addition, the concrete is often broken in the later maintenance, which seriously shortens the service life of the engineering building.

The concrete gel reducing agent is a novel additive different from other concrete additives, and has the main functions of reducing the using amount of cement and simultaneously ensuring that other performances of concrete are not reduced under the same concrete strength requirement.

Patent application publication CN110845672A reports a polycarboxylic acid type concrete gel reducing agent, which is generated by polymerizing a polyether macromonomer, unsaturated carboxylic acid, modified alcohol amine and the like, and side reactions often occur in the actual preparation process, so that the effect of the gel reducing agent is unstable, and the gel reducing agent is only compatible with a polycarboxylic acid water reducing agent, so that the application range of the gel reducing agent is limited.

Patent application publication CN110903435A reports a gel reducer and a preparation method thereof, wherein a polymer with a high molecular structure is formed under the action of unsaturated carboxylic acid and a saccharide compound by taking a common water reducer in the market as a matrix, and the gel reducer certainly improves the early strength of concrete but does not obviously improve the later strength of the concrete.

Disclosure of Invention

The invention aims to provide an ketene concrete glue reducing agent and a preparation method thereof aiming at the defects of the prior art. It can make the cement more fully disperse in the concrete, thus has improved the early strength of the concrete, and later strength. In addition, the glue reducing agent can improve the toughness and the crack resistance of concrete. The vinyl ketone concrete gel reducing agent is selected, so that the durability of concrete is increased while the cement consumption is saved, and the engineering cost is reduced.

The purpose of the invention is realized by the following technical scheme: an ketene concrete glue reducing agent comprises the following raw materials in percentage by weight:

further, the molar ratio of the dimethyl acrylic acid to the ketene monomer to the ethylene glycol to the initiator is 2-6: 1-4: 0.5-3: 0.1-0.3.

Furthermore, the mol ratio of the dimethyl acrylic acid, the ketene monomer, the ethylene glycol and the initiator is preferably 3-6: 1.5-3: 0.5-2: 0.1-0.2.

Furthermore, the ketene monomer is prepared by mixing one or more of diethylketene, methyl ketene, 3,5 dienone, 4,5 allene and the like according to any proportion.

Further, the retarder is a disaccharide compound, and the disaccharide compound comprises lactose and maltose.

Further, the retarder is preferably maltose.

Furthermore, the initiator is formed by mixing one or more of ammonium persulfate, potassium persulfate, sodium persulfate and the like according to any proportion.

Further, the initiator is preferably ammonium persulfate.

The invention also provides a preparation method of the ketene concrete gel reducing agent, which comprises the following steps:

(1) and (3) taking materials, and preparing an initiator solution with the mass percentage concentration of 3-8%.

(2) Adding an ketene monomer, dimethyl acrylic acid and ethylene glycol into a reflux reaction tank, starting stirring and gradually heating, finally heating to 90-120 ℃, and controlling the heating time to be 30-40 min;

(3) after the temperature is raised to 90-120 ℃, the initiator solution prepared in the step 1 is dripped into the solution system, the dripping speed is controlled, the dripping time is 2-3 hours, the temperature of the solution system is always constant in the dripping process, and the constant temperature reaction is continued for 3-5 hours after the dripping is finished;

(4) stopping heating, stirring and naturally cooling, adding a retarder and the balance of water when the temperature is reduced to below 60 ℃, adjusting the pH value of the solution to 9-10, stirring at a constant temperature of 35-50 ℃ for 0.5-1 hour, and finally cooling the solution to room temperature to obtain the concrete gel reducer.

The final product of the invention is an ketene polymer which is doped into concrete, on one hand, the ketene polymer can generate complex ions which are easy to dissolve in water with calcium ions and iron ions in cement slurry, soluble region points are formed on the surfaces of hydrated cement particles, so that the formation of an impermeable layer is interfered at the initial stage of hydration of the surfaces of the cement particles, the dissolution speed of tricalcium aluminate and tetracalcium aluminoferrite in the cement slurry is accelerated, further tricalcium aluminate and the like and sulfate form needle-column-shaped ettringite crystals, the crystals grow continuously, are mutually crossed and overlapped to form a framework, and are filled and reinforced by C-S-H gel and other hydrates, and the strength of the concrete is improved. On the other hand, due to the strong adsorption capacity, the free energy of the whole system can be greatly reduced, ultrafine particle aggregates in the cementing material can be effectively dispersed, and the secondary agglomeration of cement is reduced, so that cement particles are fully contacted with water, and the hydration of most of cement originally only serving as a filler in concrete is stimulated; in addition, the ketene group-containing polymer can refine and stabilize micro bubbles in slurry due to the special functional group property of the ketene group-containing polymer, the micro bubbles are similar to ball bearings, the cement dispersibility is good, a large number of micro bubbles can improve the pore structure of concrete, the flexural compression ratio of the concrete is higher than that of common concrete, the toughness and the crack resistance of the concrete are improved, and the generation of cracks is reduced. The carbohydrate selected by the retarder has a large amount of alcoholic hydroxyl groups in the structure, can be adsorbed on the surfaces of cement particles to form hydrophilic films with the same charges, enables the cement particles to repel each other, can prevent early-stage premature hydration of cement while improving the cement dispersibility, and has a certain retarding effect.

Compared with the prior art, the invention has the beneficial effects that:

(1) the ketene concrete gel reducing agent prepared by the invention contains a large amount of ketone groups, and the strong electron-withdrawing property of oxygen enables double bonds to be easily subjected to polymerization reaction so as to generate a stable polymer; moreover, the ketene functional group is easy to form an enol hydrophilic group, has good compatibility with most conventional water reducing agents such as lignosulfonate water reducing agents, polyol series water reducing agents, polycarboxylic acid series water reducing agents and the like, can further disperse cement particles under the action of the water reducing agents, promotes the hydration of the cement particles, and fully exerts the effects of reducing glue and water;

(2) the adhesive reducing agent for the ketene polymer concrete, which is obtained by the invention, can stabilize the service performance of the concrete under the condition of reducing the consumption of cement by about 15 percent;

(3) the ketene polymer concrete gel reducing agent prepared by the invention can improve the early strength and the later strength of concrete, and in addition, the gel reducing agent can increase the toughness of the concrete, improve the breaking ratio and reduce the generation of later cracks of concrete buildings.

Detailed Description

The present invention will be described in detail with reference to specific examples, but the present invention is not limited thereto.