CN111499309A - Concrete mixed with basalt fibers and metakaolin and preparation method thereof - Google Patents

Abstract

The invention relates to a concrete mixed with basalt fiber and metakaolin and a preparation method thereof. The preparation method comprises the following steps: pouring basalt and metakaolin with the monofilament diameter of 15 mu m into water, and uniformly stirring to obtain a solution A; pouring cement into the solution A, and uniformly stirring the cement with a cement stirrer to obtain a solution B; and pouring the crushed stone and sand into the solution B, adding a water reducing agent, and fully stirring by using a cement stirrer to obtain a final product. The concrete obtained by the invention has the characteristics of tensile strength, compression resistance and seepage resistance, and can be widely applied to underground spaces such as tunnels, underground stations, underground markets and the like.

Description

Concrete mixed with basalt fibers and metakaolin and preparation method thereof

Technical Field

The invention relates to a concrete mixed with basalt fibers and metakaolin and a preparation method thereof, belonging to the field of concrete preparation.

Background

With the continuous development of the modern process of China, the utilization of underground space is promoted, compared with the above-ground space, the underground structure is more complex and is influenced by various factors such as soil body extrusion, upper load, groundwater seepage and the like, so that the performance of reinforced concrete in the aspects of tensile strength, compressive strength, seepage prevention and the like becomes a key measure for solving the problems. At present, the means for enhancing the anti-seepage performance of concrete in China is mainly to add polypropylene fiber into plain concrete, but the compatibility of the polypropylene fiber and cement is poor, and the effect of enhancing the tensile property of the concrete is not obvious. Researches show that the mechanical properties such as tensile strength, elastic modulus and the like of the basalt fiber are obviously higher than those of the polypropylene fiber, the basalt fiber is low in price, can be prepared by melting and drawing basalt ore at 1500 ℃, and is the only pollution-free green fiber in the production process in the current market. Because cement and basalt fiber can not be well bonded, the cement-basalt composite cement is added with metakaolin on the basis of doping basalt, the bonding effect of the basalt and the cement is enhanced by utilizing the micro-aggregate filling effect of the metakaolin, the tensile, compression and seepage resistance of the concrete are enhanced, and meanwhile, the metakaolin particles are compact and can fully fill gaps, so that underground water seepage is resisted to a certain degree.

Disclosure of Invention

The invention aims at the problems and provides a concrete mixed with basalt fibers and metakaolin and a preparation method thereof. The technical scheme of the invention is as follows:

the concrete mixed with basalt fibers and metakaolin comprises the following components:

basalt fiber, metakaolin, cement, water, sand, gravel and a water reducing agent; the preparation method of the basalt fiber comprises the steps of melting a basalt rock body at high temperature into the basalt fiber with the monofilament diameter of 15 mu m, wherein the elastic modulus is 8200 and 8600 MPa; the cement is P.O 42.5 grade cement; the crushed stone is crushed stone with the particle size of 6mm-10 mm; the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 20%.

Further, the concrete comprises the following components in parts by weight:

0.1-0.3 part of basalt fiber, 3-8 parts of metakaolin, 15-25 parts of cement, 5-10 parts of water, 20-25 parts of sand, 55-60 parts of gravel and 0.1-0.3 part of water reducing agent.

Preferably, the impermeable concrete comprises the following components in parts by weight:

0.2 part of basalt fiber, 5 parts of metakaolin, 20 parts of cement, 6 parts of water, 24 parts of sand, 56 parts of gravel and 0.2 part of water reducing agent.

The preparation method of the concrete comprises the following specific steps:

(1) melting basalt rock mass at high temperature into basalt fiber with the monofilament diameter of 15 mu m, wherein the elastic modulus is 8200-8600MPa, P.O 42.5 grade cement is adopted as cement, broken stone with the particle size of 6-10 mm is adopted as broken stone, a polycarboxylic acid water reducing agent is adopted as the water reducing agent, and the water reducing rate is 20%;

(2) pouring basalt and metakaolin with the monofilament diameter of 15 mu m into water, and uniformly stirring to obtain a solution A;

(3) pouring cement into the solution A, and uniformly stirring the cement with a cement stirrer to obtain a solution B;

(4) and pouring the crushed stone and sand into the solution B, adding a water reducing agent, and fully stirring by using a cement stirrer to obtain a final product.

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

1. the invention aims to solve the problems, and the invention enhances the performances of the plain concrete by adding basalt fibers and metakaolin into the plain concrete so as to meet the engineering requirements. The invention determines the optimal mixing proportion by changing the diameter and the mixing amount of the doped basalt fiber, so that the basalt fiber can exert the optimal performance.

2. The basalt fiber is an inorganic fiber, takes volcano-sprayed rock mass as a raw material, has very strong chemical stability and thermal stability, has low manufacturing cost, can perfectly replace high molecular fibers such as polypropylene fiber and the like, is basically harmless to human bodies, and is a well-known nontoxic environment-friendly material.

3. The basalt fiber has extremely strong acid and alkali resistance, can well resist acid substances in soil, and weakens the corrosion of the environment to underground structures. Meanwhile, the basalt fiber also has extremely strong tensile strength, and researches show that the tensile strength of the basalt fiber exceeds that of fiber additives such as polypropylene fiber and carbon fiber. The use of the basalt fiber can greatly improve the adaptability, aging resistance and the like of the underground structure in severe environment.

4. The basalt fiber has good compatibility, and the basalt fiber is easy to disperse uniformly when being mixed with cement and sand, so that mutual gaps are greatly filled, and the structure is more compact.

5. The basalt fiber and the metakaolin are simultaneously doped, so that the workability and the durability of a concrete structure are enhanced, and the structure has good seepage-proofing and crack-resisting properties.

Detailed Description

The invention will be further described with reference to specific embodiments, and the advantages and features of the invention will become apparent as the description proceeds. The examples are illustrative only and do not limit the scope of the present invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.

Example 1: concrete mixed with basalt fibers and metakaolin and preparation method thereof

The concrete mixed with the basalt fibers and the metakaolin comprises the following components in parts by weight:

0.2 kg of basalt fiber, 5 kg of metakaolin, 20 kg of cement, 6 kg of water, 24 kg of sand, 56 kg of gravel and 0.2 kg of water reducing agent. (metakaolin, produced by Shijiazhuang mineral products Co., Ltd., has a specific surface area of 1300m²/kg)

The preparation method of the concrete comprises the following specific steps:

(1) melting basalt rock mass at high temperature into basalt fiber with the monofilament diameter of 15 mu m, wherein the elastic modulus is 8200-8600MPa, P.O 42.5 grade cement is adopted as cement, broken stone with the particle size of 6-10 mm is adopted as broken stone, a polycarboxylic acid water reducing agent is adopted as the water reducing agent, and the water reducing rate is 20%;

(2) pouring basalt and metakaolin with the monofilament diameter of 15 mu m into water, and uniformly stirring to obtain a solution A;

(3) pouring cement into the solution A, and uniformly stirring the cement with a cement stirrer to obtain a solution B;

(4) and pouring the crushed stone and sand into the solution B, adding a water reducing agent, and fully stirring by using a cement stirrer to obtain a final product.

Example 2: concrete mixed with basalt fibers and metakaolin and preparation method thereof

The concrete mixed with the basalt fibers and the metakaolin comprises the following components in parts by weight:

0.1 kg of basalt fiber, 3 kg of metakaolin, 16 kg of cement, 5 kg of water, 21 kg of sand, 55 kg of gravel and 0.1 kg of water reducing agent.

The concrete was prepared in the same manner as in example 1.

Example 3: concrete mixed with basalt fibers and metakaolin and preparation method thereof

The concrete mixed with the basalt fibers and the metakaolin comprises the following components in parts by weight:

0.3 kg of basalt fiber, 7 kg of metakaolin, 24 kg of cement, 8 kg of water, 25 kg of sand, 58 kg of gravel and 0.3 kg of water reducing agent.

The concrete was prepared in the same manner as in example 1.

Examples of the experiments

Experimental example 1: impermeability test

The experimental steps are as follows:

(1) the test piece was taken out of the curing room 1 day before the experiment and the surface was air-dried. And coating a layer of sealing material on the side surface, and pressing the test piece into the test piece sleeve preheated by the oven. After cooling slightly, the pressure is released and the extruded sealing material is eliminated. And (4) removing air bubbles in the pipeline of the impermeability instrument, and installing the test piece sleeve and the test piece on the impermeability instrument for experiment.

(2) The first time, 0.1MPa of water pressure is added, and then 0.1MPa is added every 8 hours. And observing the water seepage condition of the end face at any time.

(3) When 3 test piece terminal surfaces among 6 test pieces seeped water, water pressure was recorded, and the experiment was stopped. During the experiment, if water seeps out of the periphery, the experiment should be stopped and resealed.

The results of the experiment are shown in table 1:

TABLE 1

Test piece group number	Impervious maximum water pressure (MPa)
		Plain concrete	0.7
Concrete obtained in example 1	1.05
		Concrete obtained in example 2	1.03
Concrete obtained in example 3	1.02

And (4) experimental conclusion:

the experimental results show that when the water pressure is increased to 0.7MPa, the plain concrete leaks, and the maximum impervious water pressure of the concrete obtained by the method is obviously increased by 50 percent and reaches 1.05 MPa. According to the national waterproof technical code for underground engineering GB50108-2001 concrete impermeability index, when the concrete can resist 0.6MPa hydrostatic pressure without water seepage, the concrete reaches the impermeability concrete standard. According to experimental data, the concrete added with the metakaolin and the basalt fibers, which is prepared by the invention, has the advantage that the impermeability of the concrete is obviously improved.

Experimental example 2: splitting tensile test

The experimental steps are as follows:

the splitting tensile strength test adopts a 150mm × 150mm × 150mm cubic test piece, after standard maintenance reaches a specified age, the test piece is placed on a press machine with a spherical seat, a steel arc backing strip and a wood backing plate are padded, the axis of the test piece is aligned with the top surface of a lower press plate central backing strip of a test machine when the test piece is molded, when the upper press plate is close to the backing strip, a spherical hinge seat is adjusted to ensure contact balance, continuous and uniform loading is carried out to damage according to a specified speed, and the maximum load is recorded, wherein the test result is shown in table 2:

TABLE 2

Test piece group number	Splitting tensile strength (MPa)
		Plain concrete	2.32
Concrete obtained in example 1	2.97
		Concrete obtained in example 2	2.90
Concrete obtained in example 3	2.86

And (4) experimental conclusion:

the splitting tensile strength test is carried out on plain concrete and concrete doped with two additives, and the test result shows that the splitting tensile property of the concrete obtained by the invention is obviously improved.

Experimental example 3: axial compression test

The experimental steps are as follows:

the axial compressive strength test adopts a 150mm × 150mm × 300mm prism test piece, the standard maintenance is carried out until the specified period, the test piece is vertically placed, the axial center of the test piece is aligned with the center of a lower pressing plate of the tester, the loading is carried out at a specified speed until the test piece is damaged, and the axial compressive strength is measured, wherein the test results are shown in table 3:

TABLE 3

Test piece group number	Compressive strength (MPa)
		Plain concrete	33.10
Concrete obtained in example 1	38.92
		Concrete obtained in example 2	38.89
Concrete obtained in example 3	38.82

The experimental results are as follows:

the axial compressive strength test is carried out on plain concrete and the concrete obtained by the method, and the test result shows that the compressive strength of the concrete obtained by the method is obviously improved.

Claims (8)

1. The concrete mixed with basalt fibers and metakaolin is characterized by comprising the following components:

basalt fiber, metakaolin, cement, water, sand, gravel and a water reducing agent.

2. The basalt fiber and metakaolin blended concrete according to claim 1, wherein the basalt fiber is prepared by melting a basalt rock mass at a high temperature into basalt fiber with a monofilament diameter of 15 μm and an elastic modulus of 8200-8600 MPa.

3. The concrete blended with basalt fibers and metakaolin according to claim 1, wherein the cement is a P-O42.5 grade cement.

4. The concrete mixed with basalt fibers and metakaolin according to claim 1, wherein the crushed stone has a particle size of 6mm to 10 mm.

5. The concrete mixed with basalt fibers and metakaolin according to claim 1, wherein the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 20%.

6. The concrete mixed with basalt fibers and metakaolin according to claim 1, wherein the concrete comprises the following components in parts by weight:

0.1-0.3 part of basalt fiber, 3-8 parts of metakaolin, 15-25 parts of cement, 5-10 parts of water, 20-25 parts of sand, 55-60 parts of gravel and 0.1-0.3 part of water reducing agent.

7. The concrete mixed with basalt fibers and metakaolin according to claim 6, wherein the impermeable concrete comprises the following components in parts by weight:

0.2 part of basalt fiber, 5 parts of metakaolin, 20 parts of cement, 6 parts of water, 24 parts of sand, 56 parts of gravel and 0.2 part of water reducing agent.

8. A method for preparing a concrete according to any one of claims 1 to 7, comprising the following specific steps:

(1) melting basalt rock mass at high temperature into basalt fiber with the monofilament diameter of 15 mu m, wherein the elastic modulus is 8200-8600MPa, P.O 42.5 grade cement is adopted as cement, broken stone with the particle size of 6-10 mm is adopted as broken stone, a polycarboxylic acid water reducing agent is adopted as the water reducing agent, and the water reducing rate is 20%;

(2) pouring basalt and metakaolin with the monofilament diameter of 15 mu m into water, and uniformly stirring to obtain a solution A;

(3) pouring cement into the solution A, and uniformly stirring the cement with a cement stirrer to obtain a solution B;

(4) and pouring the crushed stone and sand into the solution B, adding a water reducing agent, and fully stirring by using a cement stirrer to obtain a final product.