CN110372300B

CN110372300B - Preparation method of fiber concrete capable of uniformly dispersing basalt fibers

Info

Publication number: CN110372300B
Application number: CN201910680493.0A
Authority: CN
Inventors: 李悦; 李洪文; 金彩云
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2019-07-26
Filing date: 2019-07-26
Publication date: 2021-09-17
Anticipated expiration: 2039-07-26
Also published as: CN110372300A

Abstract

本发明涉及使玄武岩纤维分散均匀的纤维混凝土制备方法。纤维分散剂分为两类，纤维分散剂A由浓度为1‑3g/L的4‑氨基‑1,2‑邻苯二酚盐酸盐溶液和浓度为10‑12g/L三羟甲基氨基甲烷溶液组成；纤维分散剂B由浓度为12‑15g/L的氯乙酸钠溶液、浓度为3‑5g/L碳酸氢钠溶液和浓度为15‑20g/L二甲基甲酰胺溶液组成。将玄武岩纤维放入分散剂A中搅拌3‑5分钟，然后再将其放入分散剂B中搅拌1‑3分钟，得到处理的玄武岩纤维。先将称量好的胶凝材料与处理好的玄武岩纤维混合搅拌1‑3分钟，然后加砂石、清水和聚羧酸减水剂，放在水平振动台上振动搅拌2‑5分钟，得到玄武岩纤维分散均匀的纤维混凝土。此方法有效解决了纤维不易在混凝土中均匀分散的缺陷。The invention relates to a preparation method of fiber concrete for uniformly dispersing basalt fibers. Fiber dispersants are divided into two categories. Fiber dispersant A consists of 4-amino-1,2-catechol hydrochloride solution with a concentration of 1-3g/L and trimethylolamino with a concentration of 10-12g/L The methane solution is composed; the fiber dispersant B is composed of a sodium chloroacetate solution with a concentration of 12-15g/L, a sodium bicarbonate solution with a concentration of 3-5g/L and a dimethylformamide solution with a concentration of 15-20g/L. The basalt fiber is put into dispersant A and stirred for 3-5 minutes, and then put into dispersant B and stirred for 1-3 minutes to obtain the treated basalt fiber. First, mix and stir the weighed cementitious material and the treated basalt fiber for 1-3 minutes, then add sand, water and polycarboxylate water-reducing agent, and place it on a horizontal vibrating table to vibrate and stir for 2-5 minutes to obtain Basalt fiber is uniformly dispersed fiber reinforced concrete. This method effectively solves the defect that the fibers are not easy to disperse uniformly in the concrete.

Description

Preparation method of fiber concrete capable of uniformly dispersing basalt fibers

Technical Field

The invention relates to a preparation method of fiber concrete for uniformly dispersing basalt fibers, belongs to the technical field of building materials, and can effectively solve the problem of nonuniform fiber dispersion in the fiber concrete.

Background

The common concrete has the defects of low tensile/flexural strength, poor impact resistance and the like, and the application range of the concrete is limited by the defects. The addition of fibers to concrete is the primary method to solve the above problems. Compared with common concrete, the tensile strength and the flexural strength of the fiber concrete can be improved by more than 10 percent, the impact energy value can reach 5 times of that of the common concrete, and the mechanical property is obviously improved.

Although the mechanical properties of the fiber concrete are remarkably improved, the fiber concrete has the following main problems in the preparation process: the fibers are unevenly dispersed in the concrete, so that the fibers are agglomerated in the concrete, and the improvement of the mechanical property and the durability of the concrete is greatly limited.

Basalt fiber is a new fiber rapidly developed in recent years, which is a continuous fiber drawn from natural basalt. The pure natural basalt fiber is generally brown in color and has metallic luster, is a novel inorganic environment-friendly green high-performance fiber material, and consists of oxides such as silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, iron oxide, titanium dioxide and the like. The basalt continuous fiber has high strength, and also has various excellent performances of electrical insulation, corrosion resistance, high temperature resistance and the like. In addition, the production process of the basalt fiber determines that the produced waste is less, the environmental pollution is less, and the product can be directly degraded in the environment after being discarded without any harm, so the basalt fiber is an environment-friendly material. Basalt fibers are four major fibers which are mainly developed in China. However, basalt fiber still has the problem of difficult uniform dispersion when applied to concrete materials, and in order to improve the dispersibility of the fiber in concrete, researchers have proposed many methods, for example, adding a blade to a concrete stirring shaft to enhance the dispersion of the fiber during stirring, or using an ultrasonic dispersion method to disperse the fiber in water before stirring. However, the method is simple and has a limit to improve the dispersibility of the fiber in the concrete.

Therefore, in order to solve the above problems, the present invention provides a method for preparing fiber concrete in which basalt fibers are uniformly dispersed. The method simultaneously adopts a chemical method and a physical method to improve the dispersibility of the fiber in the concrete, and effectively overcomes the defect that the improvement of the fiber dispersibility by a single method is limited.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the problem that basalt fibers are not easy to disperse in concrete, the invention provides the preparation method of the fiber concrete for uniformly dispersing the basalt fibers.

The invention adopts the following technical scheme that the special fiber dispersing agent, the fiber treatment method and the fiber concrete stirring and forming method are included.

(1) Special fiber dispersants fall into two categories:

the fiber dispersing agent A is a mixed solution of 4-amino-1, 2-catechol hydrochloride and tris (hydroxymethyl) aminomethane, the concentration of the 4-amino-1, 2-catechol hydrochloride in the mixed solution is 1-3g/L, and the concentration of the tris (hydroxymethyl) aminomethane is 10-12 g/L;

the fiber dispersing agent B is a mixed solution of sodium chloroacetate, sodium bicarbonate and dimethylformamide, the concentration of the sodium chloroacetate in the mixed solution is 12-15g/L, the concentration of the sodium bicarbonate in the mixed solution is 3-5g/L, and the concentration of the dimethylformamide is 15-20 g/L.

(2) The fiber treatment method comprises two steps:

the method comprises the following steps: mixing and stirring the dispersing agent A and the metered basalt fibers together for 3-5 minutes according to the mass ratio of 3:1-5: 1; after draining the solution, adding clear water to clean the fibers, and draining the clear water;

step two: mixing and stirring the dispersant B and the basalt fiber obtained in the step (1) according to the mass ratio of 2:1-4:1 for 1-3 minutes, draining the solution, adding clear water to clean the fiber, draining the clear water, and taking the fiber out for later use.

(3) The fiber concrete stirring and forming method comprises two steps:

the method comprises the following steps: mixing and stirring the measured cement, fly ash, mineral powder and silica fume (collectively referred to as cementing materials) and the treated basalt fiber for 1-3 minutes, and then adding the sandstone, clear water and polycarboxylic acid water reducing agent;

step two: the stirring machine is placed on a horizontal vibration table, the stirring machine and the vibration table are started simultaneously, the frequency of the horizontal vibration table is 10-20Hz, the amplitude is 2-5mm, and the fiber concrete with the basalt fibers uniformly dispersed is obtained after the horizontal vibration table is vibrated and stirred for 2-3 minutes.

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

(1) the basalt fiber is subjected to surface modification through a fiber dispersing agent, so that the basalt fiber is not easy to bond into lumps and can be uniformly dispersed in concrete;

(2) horizontally vibrating in the stirring process, and separating the fibers which are still bonded together through the vibration effect to further disperse the fibers;

(3) compared with the traditional method, the method is simple to operate and is suitable for preparing the fiber concrete on site.

Detailed Description

In order to further embody the efficacy of the present invention, the present invention is further described in detail with reference to specific application cases.

The reference blending ratio of concrete is shown in Table 1 (unit: kg):

TABLE 1 concrete base mix ratio

In table 1, cement, silica fume, fly ash and mineral powder are collectively referred to as cementitious materials.

The material parameters are as follows:

(1) the specification of the cement is P.O.42.5;

(2) the specification of the fly ash is F class I grade;

(3) the specification of the mineral powder is S95 superfine;

(4) the specific surface area of the silica fume is 18m²(iv)/g, silica content greater than 92%;

(5) the sand grain diameter is 0.25mm-0.5 mm;

(6) the particle size of the stones is 5mm-15 mm;

(7) the type of the water reducing agent is a polycarboxylic acid water reducing agent, the solid content is 25%, and the water reducing efficiency is 45%.

The concrete mix ratios used in examples 1-3 were the reference mix ratios in Table 1.

Example 1:

(1) concentration of fiber dispersant:

concentration of fiber dispersant A: the concentration of 4-amino-1, 2-catechol hydrochloride is 1g/L, and the concentration of trihydroxymethyl aminomethane is 12g/L

Concentration of the fiber dispersant B: the concentration of sodium chloroacetate is 12g/L, the concentration of sodium bicarbonate is 4g/L, and the concentration of dimethylformamide is 20g/L

(2) The length of basalt fiber is 12mm, and the mixing amount is as follows: 5.6kg

(3) The preparation process of the fiber concrete for uniformly dispersing the basalt fibers comprises the following steps

Firstly, mixing and stirring a dispersing agent A and metered basalt fibers together for 3 minutes according to a mass ratio of 3: 1; after draining the solution, adding clear water to clean the fibers, and draining the clear water;

secondly, mixing and stirring the dispersant B and the basalt fiber obtained in the step (1) for 2 minutes according to a mass ratio of 4:1, draining the solution, adding clear water to clean the fiber, draining the clear water, and taking the fiber out for later use;

thirdly, the measured cementing material and the processed basalt fiber are mixed and stirred for 1 minute, and then other materials are added

Fourthly, the mixer is placed on a horizontal vibration table, the mixer and the vibration table are started simultaneously, the frequency of the horizontal vibration table is 10Hz, the amplitude is 5mm, the vibration and the stirring are carried out for 2 minutes, and the fiber concrete with the basalt fibers uniformly dispersed is obtained

(4) Method for testing fiber dispersion performance

Firstly, the fresh concrete is randomly placed into 10 moulds with the size of 100 multiplied by 100mm, then various raw materials of the concrete are immediately cleaned by clear water, the fiber in each test mould is obtained, and the weight of the fiber is weighed.

And testing slump of the fiber concrete, 28d compressive strength and flexural strength.

Example 2:

(1) concentration of fiber dispersant:

concentration of fiber dispersant 1: the concentration of 4-amino-1, 2-catechol hydrochloride is 3g/L, and the concentration of trihydroxymethyl aminomethane is 10g/L

Concentration of fiber dispersant 2: the concentration of sodium chloroacetate is 13g/L, the concentration of sodium bicarbonate is 3g/L, and the concentration of dimethylformamide is 15g/L

(2) The length of basalt fiber is 12mm, and the mixing amount is as follows: 8.4kg

(3) The preparation process of the fiber concrete with the basalt fibers uniformly dispersed is as follows

Firstly, mixing and stirring a dispersing agent 1 and metered basalt fibers together for 3 minutes according to a mass ratio of 5: 1; after the solution is drained, clear water with the mass 4 times that of the fiber is added to clean the fiber, and then the clear water is drained;

secondly, mixing and stirring the dispersing agent 2 and the basalt fibers obtained in the step (1) for 2 minutes according to the mass ratio of 2:1, adding clear water to clean the fibers after drying the solution, then drying the clear water, and taking the fibers out for later use;

thirdly, the measured cementing material and the processed basalt fiber are mixed and stirred for 2 minutes, and then other materials are added

Fourthly, the mixer is placed on a horizontal vibration table, the mixer and the vibration table are started simultaneously, the frequency of the horizontal vibration table is 15Hz, the amplitude is 3mm, the vibration and the stirring are carried out for 2 minutes, and the fiber concrete with the basalt fibers uniformly dispersed is obtained

(4) Method for testing fiber dispersion performance

Example 3:

(1) concentration of fiber dispersant:

concentration of fiber dispersant 1: the concentration of 4-amino-1, 2-catechol hydrochloride is 2g/L, and the concentration of tris (hydroxymethyl) aminomethane is 11g/L

Concentration of fiber dispersant 2: the concentration of sodium chloroacetate is 15g/L, the concentration of sodium bicarbonate is 5g/L, and the concentration of dimethylformamide is 17g/L

(2) The length of basalt fiber is 12mm, and the mixing amount is as follows: 11.2kg

Firstly, mixing and stirring a dispersing agent 1 and metered basalt fibers together for 3 minutes according to a mass ratio of 4: 1; after draining the solution, adding clear water to clean the fibers, and draining the clear water;

secondly, mixing and stirring the dispersing agent 2 and the basalt fibers obtained in the step (1) for 2 minutes according to the mass ratio of 3:1, adding clear water with the mass 5 times of that of the fibers after draining the solution to clean the fibers, draining the clear water, and taking the fibers out for later use;

thirdly, the measured cementing material and the processed basalt fiber are mixed and stirred for 3 minutes, and then other materials are added

Fourthly, the mixer is placed on a horizontal vibration table, the mixer and the vibration table are started simultaneously, the frequency of the horizontal vibration table is 20Hz, the amplitude is 2mm, the vibration and the stirring are carried out for 2 minutes, and the fiber concrete with the basalt fibers uniformly dispersed is obtained

(4) Method for testing fiber dispersion performance

Test results

3 groups of comparison groups (serial numbers 1-3) are set, the mixing ratio of the comparison groups 1-3 is the same as the reference mixing ratio, the mixing amount of basalt is respectively 5.6kg, 8.4kg and 11.2kg, but the surface modification treatment is not carried out on the basalt fiber, a horizontal vibration table is not started in the stirring process, and other preparation and test methods are consistent with those of the invention group.

TABLE 2 test results for each group of samples

Description of the drawings: the control and invention numbers 1,2,3 represent the test results of examples 1,2, 3.

Table 2 shows the test results of the invention group and the control group. Compared with the control group, the difference between the average weight of the fibers in 10 test molds of the invention groups 1,2 and 3 and the mass of the doped basalt fibers is less than 5 percent, which shows that the dispersibility of the basalt fibers of the invention group is obviously higher than that of the control group. Slump of the invention groups 1,2 and 3 is higher than that of the comparison group, which shows that the invention group has high fiber dispersibility and better fluidity, and the comparison group has fibers agglomerated into lumps and poor fluidity; the 28d compressive strength of the invention groups 1,2 and 3 is increased by 8-10 percent compared with that of the control group, and the 28d flexural strength is increased by about 10 percent, which shows that the fiber dispersion of the invention groups is more uniform, and the mechanical strength of the concrete needs to be obviously improved.

The results in table 2 show that the basalt fibers of the invention group are uniformly dispersed compared to the control group.

Claims

1. the fiber concrete preparation method that makes basalt fiber disperse uniformly, it is characterized in that, comprise special fiber dispersant, fiber processing method and fiber concrete mixing molding method:

(1) The types of special fiber dispersants are as follows:

Fiber dispersant 1 is a mixed solution of 4-amino-1,2-catechol hydrochloride and tris(hydroxymethyl)aminomethane, and the concentration of 4-amino-1,2-catechol hydrochloride in the mixed solution is 1-3g/L, and the concentration of Tris is 10-12g/L;

Fiber dispersant 2 is a mixed solution of sodium chloroacetate, sodium bicarbonate and dimethylformamide, the concentration of sodium chloroacetate in the mixed solution is 12-15g/L, the concentration of sodium bicarbonate is 3-5g/L mixed solution, The concentration of dimethylformamide solution is 15-20g/L;

(2) The fiber treatment method is as follows:

Mix and stir dispersant 1 and the measured basalt fiber for 3-5 minutes according to the mass ratio of 3:1-5:1; after controlling the dry solution, add water with 4-5 times the fiber mass to clean the fibers, and then control the water to dry;

The dispersant 2 and the basalt fiber obtained in step (1) are mixed and stirred together for 1-3 minutes according to the mass ratio of 2:1-4:1. After controlling the solution, add clean water to wash the fibers, then control the water to dry, and take out the fibers to wait. use;

(3) The method of mixing and forming of fiber concrete is as follows:

Mix and stir the cementitious material and the treated basalt fiber for 1-3 minutes, and then put in the sand, water and polycarboxylate superplasticizer;

The mixer is placed on a horizontal vibrating table, and the mixer and the vibrating table are turned on at the same time, and then vibrated and stirred for 2-5 minutes to obtain fiber-reinforced concrete with uniformly dispersed basalt fibers.

2. According to the method of fiber concrete mixing and forming in claim 1, the vibration frequency of the horizontal vibration table is 10-20 Hz, and the amplitude is 2-5 mm.