阅读说明：本技术 一种晶种型早强剂及其制备方法 (Crystal-type early strength agent and preparation method thereof ) 是由 殷素红 林荣永 詹国良 林东 刘冠升 叶门康 于 2019-04-04 设计创作，主要内容包括：本发明公开了一种晶种型早强剂及其制备方法。所述制备方法包括如下步骤：将分散剂与水混合均匀得到悬浮液,然后将预水化水泥颗粒加入悬浮液中,得到浆体；将浆体研磨,得到悬浮液,即为所述晶种型早强剂。本发明提供的晶种型早强剂兼具早强、减水效果,且不含可能会加速钢筋锈蚀、碱骨料反应及损害混凝土后期强度的成分；本发明提供的制备方法具有工艺简单、所需原材料容易获取、对设备要求低、成本低及利于大规模推广等优点。(the invention discloses a crystal type early strength agent and a preparation method thereof. The preparation method comprises the following steps: uniformly mixing a dispersing agent and water to obtain a suspension, and then adding the pre-hydrated cement particles into the suspension to obtain slurry; and grinding the slurry to obtain a suspension, namely the crystal type early strength agent. The crystal seed type early strength agent provided by the invention has the effects of early strength and water reduction, and does not contain components which can accelerate corrosion of reinforcing steel bars, alkali aggregate reaction and damage later strength of concrete; the preparation method provided by the invention has the advantages of simple process, easy acquisition of required raw materials, low requirement on equipment, low cost, contribution to large-scale popularization and the like.)

1. The preparation method of the crystal type early strength agent is characterized by comprising the following steps:

(1) Uniformly mixing a dispersing agent and water to obtain a suspension L;

(2) Adding the pre-hydrated cement particles into the suspension L in the step (1), and uniformly mixing to obtain slurry S;

(3) and grinding the slurry S to obtain a suspension, namely the crystal type early strength agent.

2. The method of claim 1, wherein the weight parts of the following components are as follows:

5-9 parts of prehydrated cement particles;

5-11 parts of a dispersing agent;

80-90 parts of water.

3. The method of claim 1, wherein the step of preparing the pre-hydrated cement particles of step (2) comprises the steps of: and uniformly stirring water and cement to obtain cement paste, curing the cement paste, crushing, grinding and sieving to obtain the pre-hydrated cement particles.

4. the method of claim 3, wherein the water to cement water cement ratio is 0.4 to 1.0.

5. The method according to claim 3, wherein the temperature of the curing treatment is 20 to 40 degrees Celsius, and the time of the curing treatment is 1 to 28 days.

6. The production method according to claim 3, wherein the sieved mesh is a square mesh, and the sieved mesh size is 75 μm.

7. the preparation method according to claim 1, wherein the dispersant in step (1) comprises a powdery polycarboxylic acid water reducing agent.

8. The method according to claim 1, wherein the grinding time in step (3) is 3-5 hours; the grinding mode comprises wet superfine grinding.

9. The method as claimed in claim 1, wherein the median diameter of the suspended solid in the suspension in step (3) is 308-892 nm; the mass percentage concentration of suspended solids in the suspension is 10-20%.

10. a crystal-type early strength agent obtained by the production method according to any one of claims 1 to 9.

Technical Field

the invention belongs to the field of concrete admixtures, and particularly relates to a crystal type early strength agent and a preparation method thereof.

background

In order to respond to the national call of energy conservation and emission reduction, a large amount of auxiliary cementing materials are used in the construction engineering nowadays, so that the early strength of the concrete is slowly developed, and meanwhile, the engineering progress is also influenced. Particularly, as the prefabricated building is rapidly developed, problems of low turnover rate of the mold and the like, which are caused by slow development of early strength of the concrete prefabricated member in a low temperature environment, are gradually exposed, thereby seriously affecting the production efficiency and increasing the production cost. In addition, in some special projects, such as well cementing projects, the slow development of the early strength of the well cementing material directly affects the drilling progress and the quality of well cementing.

In order to solve these problems, the early strength of concrete is often improved by adding early strength agents in construction works. However, most of the conventional early strength agents increase early strength by sacrificing late strength of concrete, which limits their application and brings other adverse effects, such as: the chloride early strength agent can cause the corrosion of the steel bars and influence the durability of the reinforced concrete; alkali metal salt early strength agents increase the risk of alkali-aggregate reaction; the sulphate early strength agent can reduce the working performance of the fresh slurry; the organic early strength agent has higher use cost, the mixing amount is not easy to control, and the concrete is delayed when the mixing amount is too high; the nitrate used as the raw material in the synthesis process of the chemical synthesis hydrated calcium silicate early strength agent is a national regulated drug, and the source of the raw material is limited. In view of the above, the search for a new early strength agent suitable for the "green development" of concrete is urgent.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a crystal type early strength agent and a preparation method thereof.

Aiming at the problems of high durability risk, poor low-temperature early strength effect, high cost, limited material source and the like of the existing early strength agent, the invention provides a crystal type early strength agent and a preparation method thereof; the crystal seed type early strength agent provided by the invention has the advantages of simple preparation process, low production cost, small durability risk, capability of normally playing a role under a low temperature condition and the like, and is particularly suitable for producing a concrete prefabricated part with low requirement on the working performance of freshly-mixed concrete.

The purpose of the invention is realized by at least one of the following technical solutions.

the invention provides a preparation method of a crystal type early strength agent, which comprises the following steps:

(1) Uniformly mixing a dispersing agent and deionized water to obtain a suspension L;

(2) adding the pre-hydrated cement particles into the suspension L in the step (1), and uniformly mixing to obtain a slurry S;

(3) and (3) grinding the slurry S in a sand mill (wet superfine grinding) to obtain a suspension, namely the crystal type early strength agent.

Further, the raw materials of the crystal-type early strength agent comprise the following substances in parts by weight:

5-9 parts of prehydrated cement particles;

5-11 parts of a dispersing agent;

80-90 parts of water.

Preferably, the weight part of the raw materials for preparing the crystal-type early strength agent, the prehydrated cement particles, the dispersant and the water is 100.

Preferably, the cement is composed of 7 parts of prehydrated cement particles, 8 parts of dispersing agent and 85 parts of deionized water.

Further, the preparation of the pre-hydrated cement particles in the step (2) comprises the following steps: and uniformly stirring water and cement to obtain cement paste, curing the cement paste, crushing, grinding (grinding by a vibration mill drying method), and sieving to obtain the pre-hydrated cement particles.

Preferably, the water to cement water cement ratio is 0.4-1.0.

preferably, the temperature of the curing treatment is 20-40 ℃, and the time of the curing treatment is 1-28 days.

Preferably, the screened mesh is a square screen, the screened mesh size being 75 μm (side length of the square screen).

Preferably, the dispersant in the step (1) comprises a powdery polycarboxylic acid water reducing agent.

Further, the grinding time in the step (3) is 3-5 h.

Preferably, the grinding mode is wet superfine grinding.

The wet superfine grinding can drive zirconia ceramic beads through high-speed operation, superfine grinding is carried out on pre-hydrated cement particles in the slurry S, so that the aim of refining the seed crystal is achieved, and an anionic surfactant (powdery polycarboxylic acid water reducing agent) is added as a dispersing agent to ensure the dispersion stability of the seed crystal during the wet grinding.

Further, the median diameter (D50) of suspended solids in the suspension is 308-892 nm; the mass percentage concentration of suspended solids in the suspension is 10-20%.

The preparation method provided by the invention is characterized in that the prehydration cement particles are refined and stably dispersed in the suspension by combining physical dispersion and chemical dispersion.

The invention provides a crystal-type early strength agent prepared by the preparation method.

The invention provides a crystal form early strength agent which can reduce a nucleation barrier of hydration reaction through the actions of adsorption and nucleation, provide nucleation sites for cement hydration, shorten the setting time, accelerate the hydration reaction of cement and promote the development of early strength of concrete.

A large amount of waste slurry is generated in the production process of commercial concrete and concrete prefabricated members, fine sand and cement particles in the slurry are usually settled by a settling method, and treated water is recycled. The preparation method provided by the invention utilizes the prehydrated cement particles in the waste slurry as the raw materials of the crystal-type early strength agent, thereby realizing waste utilization, reducing environmental pollution and generating economic benefit.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) The crystal seed type early strength agent provided by the invention has the effects of early strength and water reduction, and does not contain components which can accelerate corrosion of reinforcing steel bars, alkali aggregate reaction and damage later strength of concrete;

(2) The preparation method provided by the invention has the advantages of simple process, easy acquisition of required raw materials, low requirement on equipment, low cost, contribution to large-scale popularization and the like.

Detailed Description

The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the following processes, if not described in particular detail, are all realizable or understandable by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated to the manufacturer and are considered to be conventional products available by commercial purchase.

The cement used in the examples below was a portland cement of the PI 42.5 type; the used dispersing agent is a powdery polycarboxylate superplasticizer.

The parts by weight (mass) used in the following examples may be, for example, 20g, or any other amount commonly used in the art.