阅读说明：本技术 纤维素纤维混凝土的纤维预分散方法 (Fiber pre-dispersing method of cellulose fiber concrete ) 是由 范进 许超 吴樾 于 2019-09-06 设计创作，主要内容包括：本发明公开了一种纤维素纤维混凝土的纤维预分散方法。所述方法先将片状纤维素纤维浸泡在水中使其吸水饱和,然后将纤维与硅烷偶联剂搅拌混合,使硅烷偶联剂与纤维充分接触,再加入人工机制砂和细砂,使纤维在水中呈现初步单丝形态,最后球磨,使纤维最终完全单丝分散。本发明利用纤维素纤维中空亲水的特性,使纤维吸收足够水分发生膨胀,加入的硅烷偶联剂和细砂更容易进入纤维之间的间隙,然后再进行搅拌与球磨,使片状纤维素纤维在水中具有良好的单丝分散性。(The invention discloses a fiber pre-dispersing method of cellulose fiber concrete. The method comprises the steps of soaking flaky cellulose fibers in water to enable the flaky cellulose fibers to absorb water to be saturated, then stirring and mixing the fibers and a silane coupling agent to enable the silane coupling agent to be in full contact with the fibers, then adding artificial machine-made sand and fine sand to enable the fibers to be in a primary monofilament shape in the water, and finally performing ball milling to enable the fibers to be completely dispersed in the monofilaments. The invention utilizes the hollow hydrophilic characteristic of the cellulose fiber to ensure that the fiber absorbs enough water to expand, the added silane coupling agent and fine sand can more easily enter the gaps between the fibers, and then the stirring and ball milling are carried out to ensure that the flaky cellulose fiber has good monofilament dispersibility in water.)

1. The fiber pre-dispersing method of the cellulose fiber concrete is characterized by comprising the following steps of:

step 1, fully absorbing water by cellulose fibers: completely soaking the flaky cellulose fibers into water to fully absorb water until the flaky cellulose fibers are saturated;

step 2, stirring the cellulose fibers and the silane coupling agent: mixing the cellulose fiber which fully absorbs the moisture with a silane coupling agent, and stirring at a high speed to ensure that the silane coupling agent is fully contacted with the fiber;

and 3, stirring the cellulose fibers and the sand: mixing the cellulose fiber fully contacted with the silane coupling agent with the artificial machine-made sand and the fine sand, and stirring at a high speed to convert the fiber from a sheet shape to a primary monofilament shape;

step 4, ball milling of cellulose fibers: the cellulose fibers in the preliminary monofilament form are ball milled to form the final monofilament form.

2. The fiber predispersion method according to claim 1, characterized in that in step 1, the time for absorbing water is 1 day or more.

3. The fiber pre-dispersion method according to claim 1, wherein in the step 2, the high-speed stirring speed is 80-100 rpm, and the stirring time is 40-60 minutes.

4. The fiber predispersion method according to claim 1, characterized in that in step 2, the silane coupling agent is a KH-550 type silane coupling agent, and the concentration of the silane coupling agent is 5 ‰.

5. The fiber pre-dispersion method according to claim 1, wherein in step 3, the high-speed stirring speed is 80-100 rpm, and the stirring time is 20-30 minutes.

6. The fiber pre-dispersion method of claim 1, wherein in the step 4, the ball milling time is 20 to 30 minutes.

Technical Field

The invention belongs to the technical field of preparation of cellulose fiber concrete, and relates to a fiber pre-dispersing method of cellulose fiber concrete.

Background

Portland cement is the most mainstream building engineering material rapidly due to the advantages of easily available raw materials, simple use method, superior performance and the like. However, the application scenarios of plain concrete are limited to a certain extent due to the defects that the tensile property, the bending resistance and the toughness of the plain concrete are poor, and the structural failure has the suddenness. The phenomenon can be better changed by doping the fibers into the concrete, the fibers distributed in the concrete in a disorderly way can effectively hinder the expansion of micro cracks and the formation of macro cracks in the concrete, the tensile strength, the deformation resistance and the dynamic load resistance of the plain concrete are greatly improved, and the ductility and the toughness of the concrete are effectively improved. The cellulose fiber is a third-generation concrete engineering fiber, has the characteristics of hollow interior and good hydrophilicity, can absorb water in the early stage of hydration, and release the water in the later stage of hydration, is favorable for the internal curing effect of concrete, can effectively improve the strength of the concrete, enhances the durability of the concrete, and is an important direction in the research field of fiber concrete.

From various theories of the fiber reinforcing mechanism, such as the fiber spacing theory, the composite material theory and the microscopic fracture theory, and analysis of a large number of experimental data, it can be determined that the reinforcing effect of the fibers is mainly determined by the influence of the strength of the matrix, the aspect ratio of the fibers, the volume fraction of the fibers, the bonding strength between the fibers and the matrix, and the dispersibility of the fibers in the matrix.

Research on the dispersion of the fibers in the matrix shows that the dispersion effect of the cellulose fibers in the matrix has great influence on the strength and toughness of concrete, and the cellulose fibers are organic fibers, so that the rigidity is low and the bonding is easy, so that pre-dispersion and surface treatment are needed for the fibers. However, in the experimental process, it is found that the cellulose fiber product is generally in a sheet form, complete dispersion is difficult to achieve by using a common water washing method, ball milling needs to be carried out for more than 3 hours by directly using a ball milling method, the power of the ball mill is usually high, energy consumption is high, and long-time ball milling easily causes abrasion on the fiber surface, so that the hollow hydrophilic performance of the cellulose fiber is damaged.

Disclosure of Invention

The invention aims to provide a fiber pre-dispersing method for cellulose fiber concrete, which is simple, convenient and quick and reduces energy consumption. The method utilizes the hollow hydrophilic characteristic of the cellulose fiber to ensure that the silane coupling agent is fully contacted with the cellulose fiber, thereby improving the dispersibility of the fiber in concrete and effectively improving the durability of the concrete.

The technical solution for realizing the purpose of the invention is as follows:

the fiber pre-dispersing method of the cellulose fiber concrete comprises the following steps:

step 1, fully absorbing water by cellulose fibers: completely soaking the flaky cellulose fibers into water to fully absorb water until the flaky cellulose fibers are saturated;

step 2, stirring the cellulose fibers and the silane coupling agent: mixing the cellulose fiber which fully absorbs the moisture with a silane coupling agent, and stirring at a high speed to ensure that the silane coupling agent is fully contacted with the fiber;

and 3, stirring the cellulose fibers and the sand: mixing the cellulose fiber fully contacted with the silane coupling agent with the artificial machine-made sand and the fine sand, and stirring at a high speed to convert the fiber from a sheet shape to a primary monofilament shape;

step 4, ball milling of cellulose fibers: the cellulose fibers in the preliminary monofilament form are ball milled to form the final monofilament form.

In step 1, the time for absorbing water is 1 day or more.

In the step 2, the high-speed stirring speed is 80-100 revolutions per minute, and the stirring time is 40-60 minutes.

In the step 2, the silane coupling agent is a KH-550 type silane coupling agent, and the concentration of the silane coupling agent is 5 per mill.

In the step 3, the high-speed stirring speed is 80-100 revolutions per minute, and the stirring time is 20-30 minutes.

In the step 4, the ball milling time is 20-30 minutes.

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

(1) by adopting the pre-dispersion method, the flaky cellulose fibers are dispersed into a monofilament state, can be uniformly dispersed in concrete slurry, can utilize the hollow hydrophilic characteristic of the cellulose fibers to the maximum extent, fully exert the internal curing effect and improve the durability of the concrete.

(2) The ball mill has high power and high energy consumption in long-time work, and is easy to cause large abrasion to the surface of the fiber. By the aid of the pre-dispersion method, ball milling time of the cellulose fibers is greatly shortened, the problem of abrasion of the surfaces of the fibers is optimized, and the method is beneficial to later application.

Drawings

FIG. 1 is a pictorial representation of a sheet of cellulose fibers.

FIG. 2 is a schematic representation of cellulose fibers dispersed by a conventional water washing method.

Fig. 3 is a diagram showing a state before cellulose fibers are dispersed.

Fig. 4 is a diagram showing a state after cellulose fibers are dispersed.

Fig. 5 is a flow chart of a method of the present invention.

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.

The fiber pre-dispersing method of the cellulose fiber concrete mainly comprises the following steps:

step 1, fully absorbing water by cellulose fibers: completely soaking the flaky cellulose fiber into water to ensure that the flaky cellulose fiber is in an obvious expansion state after fully absorbing water for 1 day; in consideration of the hollow hydrophilic property of the cellulose fiber, the mass ratio of water to the fiber is 100:1 when soaking, so that the water is fully absorbed.

Cellulosic fibrous material: the model is an Ultra fiber 500 model, and the main properties are as follows:

1) average length: 12 mm;

2) monofilament diameter: 18 m;

3) density: 1.10g/cm³；

4) Ultimate tensile strength: 750 MPa;

5) modulus of elasticity: 35 GPa;

6) ultimate elongation: 3.5 percent.

Step 2, stirring the cellulose fibers and the silane coupling agent: and (2) adding the cellulose fibers fully absorbing the moisture in the step (1) into a stirrer, respectively adding a KH-550 type silane coupling agent with the mass ratio of 1:8 to the fibers and water with the mass ratio of 25:1 to the fibers, and stirring for 60 minutes at a rotating speed of 80 revolutions per minute to fully contact the silane coupling agent with the surfaces of the fibers, so that the interfacial adhesion between the fibers is reduced, and the subsequent dispersion is facilitated.

And 3, stirring the cellulose fibers and the sand: and (3) adding the cellulose fibers fully contacted with the silane coupling agent in the step (2) into a stirrer together with the artificial machine-made sand and the fine sand, stirring for 30 minutes at the rotating speed of 80 revolutions per minute, and converting the fibers from a sheet shape to a primary monofilament shape by using the friction action during stirring of the fine aggregate.

In order to ensure that the friction effect of the fine aggregate can be fully exerted, the specific grading of the fine aggregate is shown in Table 1.

TABLE 1 Sieve residue of Fine aggregates in each particle size range

Step 4, ball milling of cellulose fibers: the cellulose fibers having the preliminary monofilament morphology in step 3 were ball milled for 30 minutes to develop the final dispersed state.

Fig. 1 is a physical diagram of a cellulose fiber product purchased. As can be seen from the figure, the product is in the form of a sheet, and the fibers are tightly contacted and difficult to completely disperse.

FIG. 2 is a schematic diagram of cellulose fibers dispersed by a common water washing method. It can be seen from the figure that the conventional water washing method is difficult to completely disperse the cellulose fibers and still has an agglomeration effect.

FIG. 3 is an electron micrograph of cellulose fibers before dispersion. The figure can confirm that the contact between fibers of the product is tight at a microscopic level, and the fibers are partially crossed and difficult to disperse.

FIG. 4 is an electron microscope image of cellulose fibers dispersed by the method of the present invention. It can be seen from the figure that the process disperses the cellulose fibers into a distinct monofilament state with less abrasion to the fiber surface.