CN115057664A

CN115057664A - Flame-retardant concrete for tunnel and preparation method thereof

Info

Publication number: CN115057664A
Application number: CN202210408819.6A
Authority: CN
Inventors: 李春
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-04-19
Filing date: 2022-04-19
Publication date: 2022-09-16

Abstract

The invention provides flame-retardant concrete which comprises, by mass, 5-15 parts of tricresyl phosphate and TiCl ₄ 1-5 parts of cement, 5-15 parts of fine sand, 15-20 parts of stones, 1-5 parts of mineral admixture, 1-5 parts of water reducing agent, 5-15 parts of accelerating agent, 1-5 parts of fiber material and the balance of water, wherein the total is 100 parts. The flame-retardant tricresyl phosphate is added into the concrete, so that the flame retardant property of the concrete is improved, the concrete has the characteristic of quick condensation, the using condition of the concrete for the tunnel is met, the concrete is convenient to use in tunnel engineering, and the preparation method is simple, practical and convenient to popularize and use.

Description

Flame-retardant concrete for tunnel and preparation method thereof

Technical Field

The application relates to the field of building materials, in particular to flame-retardant concrete for a tunnel and a preparation method thereof.

Background

The concrete has the characteristics of rich raw materials, low price and simple production process, so that the consumption of the concrete is increased more and more. Meanwhile, the concrete also has the characteristics of high compressive strength, good durability, wide strength grade range and the like. Due to the characteristics, the application range of the composite material is wide, and the composite material can be used in various civil engineering, especially tunnel engineering.

When the tunnel is constructed, the inner wall needs to be constructed by concrete, and the strength of the concrete is obviously reduced along with the increase of the temperature. Due to the special structure of the tunnel, once a fire disaster occurs inside the tunnel, the temperature is generally as high as over 1000 ℃, and the masonry structure inside the tunnel is usually hard to bear the high temperature, which may even cause the collapse of the tunnel to early prove a serious accident and casualty, so the fireproof design inside the tunnel is a part which needs to be considered in the tunnel construction process. At present, in the prior art, the mode of coating is mostly adopted for fire prevention and heat insulation, but the coating is often higher in cost, and has the problems of easy peeling and poor durability. Because the concrete for the tunnel has higher requirements on the conditions of the setting time, the strength and the like of the concrete, no flame-retardant concrete for the tunnel exists at present.

Disclosure of Invention

The invention aims to provide flame-retardant concrete more suitable for tunnels, which comprises 5-15 parts by mass of tricresyl phosphate and TiCl ₄ 1-5 parts of cement, 5-15 parts of fine sand, 15-20 parts of stones, 1-5 parts of mineral admixture, 1-5 parts of water reducing agent, 5-15 parts of accelerating agent, 1-5 parts of fiber material and the balance of water, wherein the total is 100 parts.

Further, the concrete comprises 10 parts of tricresyl phosphate and TiCl ₄ 1 part of cement, 12 parts of fine sand, 16 parts of stones, 4 parts of mineral admixture, 2 parts of water reducing agent, 8 parts of accelerating agent, 2 parts of fiber material and the balance of water, wherein the total is 100 parts.

It was found in this application that TiCl was added ₄ Can reduce the plasticizing effect of the tricresyl phosphate to a certain degree, improve the pumpability of the concrete and avoid the phenomenon of pipe blockage.

Further, the mineral admixture is selected from one or more of fly ash, slag powder and zeolite powder; preferably, fly ash.

Compared with other admixtures, the fly ash has better fluidity and can improve the pumpability of concrete to a certain degree.

Further, the accelerating agent is a red star 8604 type.

Different accelerators play the effect difference in different concrete formulas, screens according to the concrete standard for the tunnel in this application, under the prerequisite that does not influence fire-retardant and other properties, selects red star 8604 type accelerator.

Further, the water reducing agent is a sodium lignosulfonate water reducing agent.

Further, the fiber material is polyvinyl alcohol fiber.

Further, the cement is slag portland cement.

Furthermore, the stones are 5-16mm of continuous graded broken stones, and the particle size of the fine sand is 0.25-0.125 mm.

The properties of concrete are influenced by various factors, wherein the particle size of polyvinyl alcohol fibers, Portland slag cement, 5-16mm continuous graded broken stones and fine sand determines the sprayability and strength of the cement. Fibre, cement and rubble mutually support in this application, it is high to have obtained rupture strength through preferred, and the holding power is good, is suitable for the fire-retardant concrete that the tunnel used.

In another aspect, the present application further provides a method for preparing the above concrete, including the following steps:

putting cement, fine sand, stones and mineral admixture into a stirrer, and mixing uniformly for 1-5 min in a dry mode;

step two, adding tricresyl phosphate and TiCl ₄ Then stirring for 5-10 min;

dissolving the water reducing agent and the accelerating agent in water, adding the water reducing agent and the accelerating agent into a stirrer, and stirring for 1-5 min;

and step four, finally, adding the polyvinyl alcohol fibers into a stirrer, and continuously stirring for 1-5 min to obtain the concrete slurry.

On the other hand, the application also provides the application of the concrete or the concrete prepared by the method in tunnel engineering.

The invention has the following beneficial effects:

1. the flame-retardant tricresyl phosphate is added into the concrete, so that the flame-retardant property of the concrete is improved, and a novel preparation method of the flame-retardant concrete is provided;

2. the concrete has the characteristic of rapid setting, meets the use conditions of the concrete for the tunnel, and is convenient to use in tunnel engineering;

3. the preparation method of the flame-retardant concrete for the tunnel is simple, practical and convenient to popularize and use.

Detailed Description

In order to more clearly explain the overall concept of the present application, the following detailed description is given by way of example. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.

The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer.

Wherein the tricresyl phosphate is provided by a Haian petrochemical plant of Jiangsu province; portland slag cement and portland pozzolanic cement are provided by cement of tangshanji east, ltd; polyvinyl alcohol fibers and polypropylene fibers are provided by Shandong Yitai engineering materials Co., Ltd; fly ash, slag powder, steel slag powder, phosphorus slag powder, silica fume and zeolite powder are produced by a Guangmeng mineral product processing factory in Lingshou county; sodium lignosulfonate water reducing agent and naphthalene high-efficiency water reducing agent are provided by the chemical company Jinan Jiabin; the 8604-type quick-setting admixture and the I-type quick-setting admixture are provided by Henan Tourden building materials GmbH; the JS2000 concrete mixer is provided by Zhengzhou Changli machinery manufacturing limited company, and the rotating speed is 21 r/min.

In the following embodiments, reagents or instruments used are not indicated by manufacturers, and are all conventional products available by commercial purchase, unless otherwise specified.

Wherein the grain diameter of the fine sand is 0.25 mm-0.125 mm.

EXAMPLE 1 Effect of tricresyl phosphate content on concrete Heat resistance

Adding the admixture of cement, fine sand, gravel and mineral into a JS2000 concrete mixer according to the proportion, mixing uniformly for 3min, adding tricresyl phosphate, mixing uniformly for 5min, dissolving the water reducing agent and the accelerating agent into water, adding into the mixer, and stirring for 3 min. And finally, adding the polyvinyl alcohol fibers into the stirrer, and continuously stirring for 3min to obtain the concrete slurry.

Wherein the cement is slag portland cement, the mineral admixture is phosphorous slag powder, the water reducing agent is sodium lignosulfonate water reducing agent, the accelerator is monascus 8604 type, and the stones are 5-16mm continuous graded broken stones.

The ratio of the cement, the fine sand, the pebbles and the mineral is 6:8:8: 2. According to the mass percentage of the cement, 2 percent of polyvinyl alcohol fiber, 8 percent of accelerating agent, 2 percent of water reducing agent and tricresyl phosphate with different contents are added. The JGJ/T372-2016 specification stipulates that the water-cement ratio of the high-strength sprayed concrete is not more than 0.45, so that the water-cement ratio of the high-strength sprayed concrete is 0.4.

After the mixture was mixed uniformly, the mixture was subjected to a spray operation using a GYP-90C hydraulic pump-fed wet sprayer. And (3) after the sprayed concrete sample is coated with a film and maintained, the sprayed concrete sample is placed indoors for one day, then the mold is removed, and after 7 days, a fire resistance test is carried out.

The fire endurance test method comprises the specific steps of firstly arranging a test piece on a support of a combustion testing machine, simultaneously arranging two thermocouples in the middle of the back fire surface of the test piece, fixing a thermocouple probe, penetrating thermocouple wires out of a small hole in the right side of the combustion testing machine and connecting the thermocouple wires to a temperature collection box, and forming a temperature collection system by the temperature collection box and a computer for storing data. Firing the test piece by using a J2609 type seat type alcohol blast burner right below the test piece, wherein the distance between a nozzle and the surface is about 70mm, covering a 5-8 cm thick asbestos felt thermal insulation layer on a cement asbestos plate, recording the temperature of a thermocouple every 1min, recording the time required for the temperature to reach 220 ℃ and the combustion temperature for 100min, and the test process is shown in Table 1.

TABLE 1

As can be seen from Table 1, the concrete refractoriness index increases and then decreases with the increase of tricresyl phosphate content, and at 10%, the concrete heat resistance is the best. However, in the experimental process, the pumpability is poor along with the increase of the content of the tricresyl phosphate, and the phenomenon of pipe blockage is obvious.

EXAMPLE 2 Effect of different mineral admixtures on concrete pumpability

Under the preferred conditions mentioned above, different mineral blends are selectedThe materials are tested, and TiCl with the content of 1 percent is added into tricresyl phosphate according to the mass percentage of cement ₄ . The presence or absence of the pipe blockage phenomenon in the use process was observed, and the results are shown in table 2.

TABLE 2

Mineral admixture	Pipe blockage phenomenon
		Phosphorous slag powder	Seriously blocked pipe
Slag powder	Seriously blocked pipe
		Steel slag powder	Seriously blocked pipe
Fly ash	Slightly blocked pipe
		Silica fume	Seriously blocked pipe
Zeolite powder	Slightly blocked pipe
		Fly ash and 1% TiCl ₄	Is free of
Zeolite powder + 1% TiCl ₄	Slightly blocked pipe

As can be seen from the results in Table 2, different mineral admixtures have some effect on the pumpability of the concrete. Wherein, the fly ash and TiCl ₄ The common use can obviously improve the pipe blockage phenomenon caused by adding the tricresyl phosphate and improve the pumpability of the concrete containing the tricresyl phosphate. Compared with other admixtures, the fly ash and the zeolite powder have better fluidity, the pumpability of concrete can be improved to a certain degree, and TiCl is added on the basis of the fly ash ₄ Can reduce the plasticizing effect of the tricresyl phosphate to a certain extent, further improve the pumpability of the concrete and avoid the phenomenon of pipe blockage.

Test example 1

Adding the admixture of cement, fine sand, gravel and mineral into a JS2000 concrete mixer according to the proportion, dry-mixing and uniformly mixing for 3min, adding tricresyl phosphate and TiCl ₄ Mixing uniformly for 5min, dissolving the water reducing agent and the accelerating agent in water, adding into a stirrer, and stirring for 3 min. And finally, adding the polyvinyl alcohol fibers into a stirrer and continuously stirring for 3min to obtain the concrete slurry.

The cement is slag portland cement, the mineral admixture is selected from fly ash, the water reducing agent is sodium lignin sulfonate, the accelerating agent is monascus 8604 type, and the stones are 5-16mm continuous graded broken stones.

The mass ratio of the cement to the fine sand to the stone to the mineral admixture is 6:8:8: 2. Adding 2 percent of polyvinyl alcohol fiber, 8 percent of accelerating agent, 2 percent of water reducing agent and 1 percent of TiCl according to the mass percentage of the cement ₄ And 10% tricresyl phosphate.

Test example 2

The difference from the test example 1 is only that the water reducing agent is a naphthalene-based superplasticizer.

Test example 3

The difference from test example 1 is only that the water-reducing agent content is 4%.

Test example 4

The only difference from test example 1 is that the cement is a pozzolanic portland cement.

Test example 5

The only difference from test example 1 was that the fibers were polypropylene fibers.

Test example 6

The difference from the test example 1 is only that the ratio of the cement, fine sand, gravel and mineral blend is 6:9:8: 4.

Test example 7

The difference from test example 1 is only that the setting accelerator is a red star type I.

Test example 8

The difference from test example 1 is only that the accelerator content is 6%.

Test example 9

The difference from the test example 1 is only that the stones are 5-10mm continuous graded crushed stones.

EXAMPLE 3 Effect of different factors on concrete spray Strength

Concrete was obtained by mixing in the manner of test examples 1 to 9.

The test method of the strength of the sprayed concrete refers to the standard JGJ/T372-2016 and the test method standard of the physical and mechanical properties of the concrete (GB/T50081-2019).

The slump of the concrete mixture is tested according to the standard of the test method for the performance of common concrete mixtures (GB/T50080-2016).

The setting time test method refers to a standard accelerator for sprayed concrete (GB/T31359-2017), and an average value is taken for 3 times of tests in each group. The test results are shown in table 3.

Through advanced test, the slump is more suitable when the slump is about 210 mm.

TABLE 3

Note: the setting time is the final setting time.

As can be seen from Table 3, the slump of the obtained concrete is affected by the kind of water-reducing agent, the content of water-reducing agent, the kind of accelerator, the content of accelerator, the kind of cement, the kind of fiber, the continuous grain size of gravel and the mass ratio of cement, fine sand, gravel and mineral admixture. The concrete is made of slag portland cement, the water reducing agent is sodium lignosulfonate, the water reducing agent is 2%, the accelerator is 8604 type red star, the accelerator is 8%, the fiber is polyvinyl alcohol fiber, the pebbles are 5-16mm continuous graded broken stones, and when the mixing ratio of the cement, the fine sand, the pebbles and the mineral is 6:8:8:2, the slump is most appropriate, the spraying amount is just 212mm, the breaking strength and the fire resistance are good, the rapid solidification requirement of the concrete for the tunnel is met, and the fire resistance of the concrete is improved due to the fact that the concrete contains the flame retardant component. The properties of concrete are influenced by various factors, wherein the sprayability and the strength of the cement are determined by the polyvinyl alcohol fibers, the portland slag cement and 5-16mm continuous graded broken stones. And the mutual cooperation of the fiber, the cement and the broken stone ensures that the concrete has high breaking strength and good supporting force and is suitable for tunnels.

The concrete can realize low smoke, leakage prevention, high hardness and quick condensation in flame retardance, and is suitable for various tunnel projects.

The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. The flame-retardant concrete is characterized by comprising, by mass, 5-15 parts of tricresyl phosphate and TiCl ₄ 1-5 parts of cement, 5-15 parts of fine sand, 15-20 parts of stones, 1-5 parts of mineral admixture, 1-5 parts of water reducing agent, 5-15 parts of accelerating agent, 1-5 parts of fiber material and the balance of water, wherein the total is 100 parts.

2. The fire retardant concrete of claim 1, wherein the fire retardant concrete comprises 10 parts tricresyl phosphate, TiCl ₄ 1 part of cement, 12 parts of fine sand, 16 parts of stones, 4 parts of mineral admixture, 2 parts of water reducing agent, 8 parts of accelerating agent, 2 parts of fiber material and the balance of water, wherein the total is 100 parts.

3. The flame retardant concrete according to claim 1, wherein the mineral admixture is selected from one or more of fly ash, slag powder and zeolite powder; preferably, fly ash.

4. The fire retardant concrete of claim 1, wherein the accelerator is a red star 8604 type.

5. The fire retardant concrete of claim 1, wherein the water reducing agent is sodium lignosulfonate.

6. The fire retardant concrete of claim 1, wherein the fiber material is polyvinyl alcohol fiber.

7. The fire retardant concrete of claim 1, wherein the cement is a portland slag cement.

8. The fire retardant concrete according to claim 1, wherein the stones are 5-16mm continuous graded broken stones, and the fine sand has a particle size of 0.25-0.125 mm.

9. A method of producing fire retardant concrete according to any one of claims 1 to 8, characterised in that it comprises the steps of:

step two, adding tricresyl phosphate and TiCl ₄ Then stirring for 5-10 min;

10. Use of a concrete according to any one of claims 1 to 8 or a concrete prepared by the method according to claim 9 in tunnel engineering.