A heat-resistant concrete and a method for producing the same

Abstract

The application discloses a kind of heat-resistant concrete and preparation method thereof, heat-resistant concrete includes the following weight fraction components: cement 200~300 parts, mineral admixture 50~200 parts, fine aggregate 800~1200 parts, coarse aggregate 800~1200 parts, water 140~180 parts, polycarboxylate superplasticizer 5~15 parts, heat resistance reinforcing component 5-30 parts.The heat resistance reinforcing component is polyphosphazene micropipe and polyphosphazene micropipe dispersion reinforcing component are mixed according to weight component 1:100.The polyphosphazene micropipe tube diameter is 5~15 microns, length-diameter ratio is 20~40, wall thickness is 50~200 nanometers.The polyphosphazene micropipe dispersion reinforcing component is 1-ethyl-3-methylimidazole diethyl phosphate salt and methylhydroxyethyl cellulose mixed solution, and the weight component of the two is 20:1.Heat-resistant concrete heat-resistant temperature reaches 600 DEG C and each performance is excellent.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a heat-resistant concrete and its preparation method. Background Technology

[0002] With industrial development and technological advancements, special concrete has been increasingly applied in practical engineering projects. Among them, heat-resistant concrete is a type of special concrete that can be used for extended periods at temperatures ranging from 200℃ to 900℃ while maintaining its mechanical properties and volume stability. It is primarily used in the foundations of metallurgical engineering projects and as chimney linings. Ordinary concrete, after hardening, is a dense whole formed by hydration products and aggregates, containing some micro- and nano-pores and moisture. When concrete is heated to 200℃, the cement hydration products begin to dehydrate, causing the concrete to shrink and cracks to appear; the strength initially increases slightly but then decreases. At 500℃, strong calcium oxide begins to dehydrate, and the cementitious structure begins to break down. At 573℃, the quartz crystals in the aggregate undergo an α-to-β-quartz crystal transformation, resulting in volume expansion. After 600℃, the calcium carbonate in the aggregate begins to decompose, further damaging the concrete structure. At 800℃, hydrated calcium silicate loses its binding capacity. At 900℃, the calcium carbonate in the aggregate completely decomposes, leading to concrete structural failure and loss of strength.

[0003] In existing technologies, aluminate cement and refractory high-alumina aggregate are commonly used to prepare heat-resistant concrete. However, aluminate cement has a short setting time and loses its workability quickly; refractory high-alumina aggregate has high porosity and high water absorption, which further reduces the workability of the concrete and makes it unsuitable for large-scale applications and pumping operations. Therefore, there are still many problems in practical use. Summary of the Invention

[0004] The purpose of this invention is to provide a heat-resistant concrete with a heat resistance temperature of up to 600℃ and excellent performance in various aspects. It mainly improves the expansion resistance of the concrete when heated by incorporating heat-resistant reinforcing components, reduces cracks, improves quality stability and strength stability, and increases the heat resistance of the concrete.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A heat-resistant concrete comprises the following components in parts by weight: 200-300 parts silicate cement, 50-200 parts mineral admixtures, 800-1200 parts fine aggregate, 800-1200 parts coarse aggregate, 140-180 parts water, 5-15 parts polycarboxylate superplasticizer, and 5-30 parts heat-resistant reinforcing components.

[0007] Preferably, the mineral admixture is one or a combination of several of the following: fly ash, silica fume, phosphorus slag powder, and blast furnace slag powder.

[0008] Preferably, the fine aggregate is manufactured sand and the lithology is limestone.

[0009] Preferably, the coarse aggregate is crushed stone, and the lithology is limestone.

[0010] Preferably, the heat resistance enhancing component is a mixture of polyphosphazene microtubes and polyphosphazene microtube dispersion reinforcing components in a weight ratio of 1:100.

[0011] Preferably, the polyphosphazene microtube has a diameter of 5–15 micrometers, an aspect ratio of 20–40, and a wall thickness of 50–200 nanometers.

[0012] Preferably, the polyphosphazene microtube dispersion reinforcing component is a mixed solution of 1-ethyl-3-methylimidazolium phosphate diethyl ester salt and methyl hydroxyethyl cellulose in a weight ratio of 20:1.

[0013] The method for preparing the concrete is characterized in that,

[0014] The heat-resistant reinforcing component is prepared by weighing 1-ethyl-3-methylimidazolium diethyl phosphate salt, adding methyl hydroxyethyl cellulose, heating to 100°C, and continuing for 1-3 hours until the cellulose is partially dissolved but not completely dissolved, thus obtaining the polyphosphazene microtube reinforced dispersion component, which is then mixed with polyphosphazene microtubes.

[0015] Weigh the raw materials by weight: cement, mineral admixtures, fine aggregate, coarse aggregate, water, and polycarboxylate superplasticizer. Mix the cement and mineral admixtures evenly. Add the polycarboxylate superplasticizer and 3 / 4 water and stir. Then add the heat-resistant reinforcing component and 1 / 4 water. Finally, add the fine aggregate and coarse aggregate and stir evenly to obtain heat-resistant concrete.

[0016] When concrete is subjected to high temperatures, three main problems occur: first, the internal chemical substances decompose, losing their binding ability; second, the aggregate deforms and breaks down due to heat; and third, the internal moisture generates enormous steam pressure, causing expansion and cracking. At 600℃, the main cause of damage to heat-resistant concrete using limestone aggregate comes from internal expansion stress. Using common silicate cement and limestone aggregate to produce heat-resistant concrete at 600℃ maintains good workability and pumpability, avoids the use of aggregates with high silica content, and ensures aggregate stability. Adding polyphosphazene microtubes enhances the heat resistance of the concrete, ultimately resulting in a concrete with excellent heat resistance.

[0017] Polyphosphazene is a novel organic / inorganic hybrid polymer with alternating phosphorus and nitrogen atoms as the main chain, and two organic side groups usually connected to phosphorus atoms by chemical bonds. It exhibits good thermal stability, is not easily decomposed at high temperatures, and has high strength. The polyphosphazene microtube dispersion reinforcing component is a composite product of polymer fibers and ionic liquids. Ionic liquids are ionic substances that are liquid near room temperature, exhibiting stable properties and being environmentally friendly. Cellulose dissolves into fragments in the ionic liquid and then forms a composite structure with side chains with the polyphosphazene microtubes. The side-chain structure of the polyphosphazene microtubes makes them less prone to aggregation and provides good stability. When dispersed in concrete, the polyphosphazene microtubes act as a filler component, increasing the density of the concrete. The hollow structure of the polyphosphazene microtubes connects micro- and nano-pores, providing channels for moisture expansion and release after high-temperature heating, thus increasing the concrete's resistance to expansion and cracking.

[0018] In summary, the beneficial effects of this invention compared to the prior art are:

[0019] Polyphosphononitrile microtubes tend to agglomerate in water and have poor dispersibility when added alone to concrete. By using polyphosphononitrile microtubes to disperse reinforcing components, the dispersibility of polyphosphononitrile microtubes is improved, allowing them to be uniformly dispersed in concrete and making their structure less susceptible to damage.

[0020] The polyphosphazene microtubes incorporated in this invention have a hollow structure and connect to the micropores inside the concrete through hollow pipes. After high-temperature heating, they form channels for the expansion and release of water vapor, balancing the water vapor pressure in different pores. Furthermore, the incorporated polyphosphazene microtubes at the micron size can enhance the bonding performance of the slurry and synergistically enhance the high-temperature anti-cracking performance of the concrete. Detailed Implementation

[0021] The technical solution of the present invention will be further described in detail below through embodiments. These embodiments are intended to explain the present invention and not to limit it.

[0022] Example 1

[0023] The raw materials are weighed in the following proportions: 200 parts P·O52.5 cement, 40 parts phosphorus slag powder, 60 parts fly ash, 1050 parts manufactured sand, 900 parts crushed stone, 155 parts water, 7 parts polycarboxylate superplasticizer, and 10 parts heat-resistant reinforcing component. The cement, phosphorus slag powder, and fly ash are mixed evenly. The polycarboxylate superplasticizer and 3 / 4 of the water are added and stirred. Then the heat-resistant reinforcing component and 1 / 4 of the water are added. Finally, the manufactured sand and crushed stone are added and stirred evenly to obtain a heat-resistant concrete.

[0024] Example 2

[0025] The raw materials are weighed in the following proportions: 240 parts P·O52.5 cement, 40 parts mineral powder, 60 parts fly ash, 1000 parts manufactured sand, 900 parts crushed stone, 160 parts water, 10 parts polycarboxylate superplasticizer, and 15 parts heat-resistant reinforcing component. The cement, mineral powder, and fly ash are mixed evenly. The polycarboxylate superplasticizer and 3 / 4 of the water are added and stirred. Then the heat-resistant reinforcing component and 1 / 4 of the water are added. Finally, the manufactured sand and crushed stone are added and stirred evenly to obtain a heat-resistant concrete.

[0026] Example 3

[0027] The raw materials are weighed in the following proportions by weight: 300 parts P·O52.5 cement, 40 parts silica fume, 60 parts fly ash, 900 parts manufactured sand, 1000 parts crushed stone, 165 parts water, 12 parts polycarboxylate superplasticizer, and 20 parts heat-resistant reinforcing component. The cement, silica fume, and fly ash are mixed evenly. The polycarboxylate superplasticizer and 3 / 4 of the water are added and stirred. Then the heat-resistant reinforcing component and 1 / 4 of the water are added. Finally, the manufactured sand and crushed stone are added and stirred evenly to obtain a heat-resistant concrete.

[0028] Compare with Example 1

[0029] The raw materials are weighed in the following proportions: 200 parts P·O52.5 cement, 40 parts phosphorus slag powder, 60 parts fly ash, 1050 parts manufactured sand, 900 parts crushed stone, 155 parts water, and 7 parts polycarboxylate superplasticizer. The cement, phosphorus slag powder, and fly ash are mixed evenly. The polycarboxylate superplasticizer and 3 / 4 of the water are added and stirred. Then, 1 / 4 of the water is added, and finally, the manufactured sand and crushed stone are added and stirred evenly to obtain the final product.

[0030] Compare with Example 2

[0031] The raw materials are weighed in the following proportions: 200 parts P·O52.5 cement, 40 parts phosphorus slag powder, 60 parts fly ash, 1050 parts manufactured sand, 900 parts crushed stone, 155 parts water, 7 parts polycarboxylate superplasticizer, and 10 parts polyphosphonic acrylonitrile microtubes. The cement, phosphorus slag powder, and fly ash are mixed evenly. The polycarboxylate superplasticizer and 3 / 4 of the water are added and stirred. Then, the polyphosphonic acrylonitrile microtubes and 1 / 4 of the water are added. Finally, the manufactured sand and crushed stone are added and stirred evenly to obtain the final product.

[0032] Compare with Example 3

[0033] The raw materials are weighed in the following proportions: 200 parts P·O52.5 cement, 40 parts phosphorus slag powder, 60 parts fly ash, 1050 parts manufactured sand, 900 parts crushed stone, 155 parts water, 7 parts polycarboxylate superplasticizer, and 10 parts polyphosphonic acrylonitrile microtube dispersion reinforcing component. The cement, phosphorus slag powder, and fly ash are mixed evenly. The polycarboxylate superplasticizer and 3 / 4 of the water are added and stirred. Then the polyphosphonic acrylonitrile microtube dispersion reinforcing component and 1 / 4 of the water are added. Finally, the manufactured sand and crushed stone are added and stirred evenly to obtain the final product.

[0034] Examples 1-3 present trial mix designs for heat-resistant concrete of grades C30, C40, and C50, respectively. Control Examples 1-3 use Example 1 as the control group for comparative testing. The performance characteristics of the examples and control examples were tested, and the results are shown in Table 1 below:

[0035] The 600℃ heat resistance test is as follows: take 3 specimens from each group, cure them under standard conditions for 28 days, dry them at 110℃ for 24 hours, place them in a high-temperature furnace, and burn them at a constant temperature of 600℃ for 24 hours. Then, let them cool naturally to room temperature.

[0036] Table 1 Performance test results of Examples 1-3 and Comparative Examples 1-3

[0037]

[0038] As shown in the table above, the slump of Examples 1-3 was in the range of 200-220 mm, and the spread was above 600 mm, indicating good overall workability. Their 28-day standard curing strength also met the requirements. After the heat resistance test, the compressive strength of Examples 1-3 decreased only slightly, with a strength loss rate between 11.0% and 14.8%, and a mass loss rate between 1.1% and 1.6%. Control Example 1, without the addition of heat-resistant reinforcing components, had a strength loss rate of 44.8% and a mass loss rate of 5.3%, the highest among all examples. Control Example 2 included polyphosphonic acrylonitrile microtubes but no polyphosphonic acrylonitrile microtube dispersion. The poor dispersibility of polyphosphonic acrylonitrile microtubes in concrete meant that many agglomerated microtubes could not fully exert their bonding effect and might even become weak phases, resulting in a slightly lower 28-day strength. The strength loss rate of Control Example 2 after high temperature was also 28.7%, and the mass loss rate was 2.7%, slightly lower than that of Control Example 1. In Comparative Example 3, polyphosphonic acrylonitrile microtubes were added to disperse the reinforcing component, while those without polyphosphonic acrylonitrile microtubes showed higher strength and mass loss rates, and no high-temperature reinforcing effect was observed. Therefore, the addition of a mixture of polyphosphonic acrylonitrile microtubes and polyphosphonic acrylonitrile microtube dispersion reinforcing components to concrete significantly improved its high-temperature resistance and demonstrated excellent high-temperature properties in high-temperature resistance tests exceeding the standard.

[0039] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A heat-resistant concrete, characterized in that, The composition comprises the following components in parts by weight: 200-300 parts cement, 50-200 parts mineral admixtures, 800-1200 parts fine aggregate, 800-1200 parts coarse aggregate, 140-180 parts water, 5-15 parts polycarboxylate superplasticizer, and 5-30 parts heat-resistant reinforcing component. The heat-resistant reinforcing component is a mixture of polyphosphazene microtubes and polyphosphazene microtube dispersion reinforcing component in a weight ratio of 1:

100. The polyphosphazene microtubes have a diameter of 5-15 micrometers, an aspect ratio of 20-40, and a wall thickness of 50-200 nanometers. The polyphosphazene microtube dispersion reinforcing component is a mixed solution of 1-ethyl-3-methylimidazolium phosphate diethyl ester salt and methyl hydroxyethyl cellulose in a weight ratio of 20:

1.

2. The heat-resistant concrete as described in claim 1, characterized in that, The mineral admixture is one or a combination of several of the following: fly ash, silica fume, phosphorus slag powder, and blast furnace slag powder.

3. The heat-resistant concrete as described in claim 1, characterized in that, The fine aggregate is manufactured sand, and the lithology is limestone.

4. The heat-resistant concrete as described in claim 1, characterized in that, The coarse aggregate is crushed stone, and the lithology is limestone.

5. The method for preparing heat-resistant concrete according to any one of claims 1-4, characterized in that, Weigh the raw materials by weight: cement, mineral admixtures, fine aggregate, coarse aggregate, water, polycarboxylate superplasticizer, and heat-resistant reinforcing component. Mix the cement and mineral admixtures evenly. Add the polycarboxylate superplasticizer and 3 / 4 water and stir. Then add the heat-resistant reinforcing component and 1 / 4 water. Finally, add the fine aggregate and coarse aggregate and stir evenly to obtain heat-resistant concrete. The preparation method of the heat-resistant reinforcing component is as follows: Weigh 1-ethyl-3-methylimidazolium diethyl phosphate salt, add methyl hydroxyethyl cellulose and heat to 100°C for 1-3 hours to obtain polyphosphazene microtube dispersed reinforcing component. Then add polyphosphazene microtubes and mix to obtain the heat-resistant reinforcing component.

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