CN110342838B

CN110342838B - High-heat-conductivity cement clinker and preparation method and application of cement product thereof

Info

Publication number: CN110342838B
Application number: CN201910625018.3A
Authority: CN
Inventors: 叶正茂; 景国建; 冯浩然; 李全亮; 王树贤; 程新
Original assignee: University of Jinan
Current assignee: University of Jinan
Priority date: 2019-07-11
Filing date: 2019-07-11
Publication date: 2021-08-31
Anticipated expiration: 2039-07-11
Also published as: CN110342838A

Abstract

The invention belongs to the technical field of cement preparation processes, and particularly relates to a high-thermal-conductivity cement clinker, and a preparation method and application of a cement product thereof. The method comprises the following steps: 1) ultrasonically dispersing graphene oxide into an isopropanol solution to obtain a graphene oxide-isopropanol dispersion solution for later use; 2) adding the cement clinker powder into the graphene oxide-isopropanol dispersion liquid obtained in the step 1), and continuously stirring until all graphene oxide is adsorbed on the surface of the cement clinker; then, carrying out material-liquid separation on the obtained wet material to obtain cement clinker with the surface coated with graphene oxide; 3) annealing the cement clinker obtained in the step 2) at a set temperature, removing residual isopropanol and reducing functional groups in graphene oxide, and obtaining the cement clinker with the surface coated with graphene, namely the high-heat-conductivity cement clinker. The method disclosed by the invention can effectively improve the heat-conducting property of the cement product and can avoid the problems of adaptability and the like of the cement product caused by adding the graphene dispersing agent.

Description

High-heat-conductivity cement clinker and preparation method and application of cement product thereof

Technical Field

The invention belongs to the technical field of cement preparation processes, and particularly relates to a high-thermal-conductivity cement clinker, and a preparation method and application of a cement product thereof.

Background

The information disclosed in this background of the invention is only for enhancement of understanding of the general background of the invention and is not necessarily to be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Cement materials are one of the most widely used building materials in the world. For nearly three centuries, engineering structures using cement concrete as a building material have played a very critical role in human activities such as urban traffic construction. With the development of society, people do not only limit the performance requirements of cement materials in terms of strength, but also pay more and more attention to the functionality of the cement materials. One of the researches on cement with high thermal conductivity is. Generally, cement materials have a relatively low thermal conductivity, which limits their use in many applications. For example, in the field of industrial heat tracing and heat exchange, if the heat conductivity coefficient of cement can be greatly improved, the heat conduction area can be increased in a heat tracing and heat exchange device, and a high-efficiency low-heat-resistance heat transfer channel is established, so that the purposes of improving the heat transfer efficiency and reducing the energy consumption are achieved. In addition, the temperature cracks existing in mass concrete are also caused by low heat conductivity coefficient of cement, so that the improvement of the heat conductivity of the cement has a remarkable influence on the control of the temperature cracks of the concrete.

Generally, the heat-conducting property of cement is enhanced by adding heat-conducting fillers. Substances such as carbon black, graphite, iron powder, heat-conducting fibers and the like are widely applied to improving the heat conductivity of cement materials. However, these materials have a limited improvement effect when added to cement due to their low thermal conductivity. At the same time, the dispersibility of the thermally conductive filler in cement limits its further applications. Since andreGeim discovered graphene and gained Nobel prize, graphene has many excellent properties such as ultrahigh electrical and thermal conductivity and strength, and is rapidly a major hot spot for research in the whole material field. Graphene is the thinnest novel nano material with the greatest strength and the strongest electric and heat conduction capability found at present. In recent years, many studies have attempted to introduce graphene into cement-based materials, taking advantage of its excellent thermal conductivity properties to improve the thermal properties of cement-based materials. For example, patent document CN106587847A discloses a graphene-cement-based high thermal conductivity composite material and a preparation method thereof, which comprises modifying graphene with a silane coupling agent, improving the dispersibility of graphene in cement by ball milling and mixing, and finally preparing a cement material by a hot press molding process. However, the inventors believe that: although the method effectively improves the heat conductivity of cement, the preparation method is complicated, and substances such as added phenolic resin and dispersing agent have the problem of adaptability to cement matrix, so that further research on how to more effectively use graphene for improving the heat conductivity of cement is needed.

Disclosure of Invention

In view of the above problems, the present invention aims to provide a highly heat conductive cement clinker and a preparation method and application of a cement product thereof. The method disclosed by the invention can effectively improve the heat-conducting property of the cement product, and can avoid the problems of adaptability and the like of the cement product caused by adding the graphene dispersing agent.

The first object of the present invention: provides a preparation method of high heat-conducting cement clinker.

The second object of the present invention: provides a preparation method of a high-thermal-conductivity cement product.

The third object of the present invention: provides the application of the preparation method of the high-heat-conductivity cement clinker and the cement product.

In order to realize the purpose, the invention discloses the following technical scheme:

firstly, the invention discloses a preparation method of high-heat-conductivity cement clinker, which comprises the following steps:

(1) ultrasonically dispersing graphene oxide into an isopropanol solution to obtain a graphene oxide-isopropanol dispersion solution for later use;

(2) adding the cement clinker powder into the graphene oxide-isopropanol dispersion liquid obtained in the step (1), and continuously stirring until all graphene oxide is adsorbed on the surface of the cement clinker; then, carrying out material-liquid separation on the obtained wet material to obtain cement clinker with the surface coated with graphene oxide;

(3) and (3) annealing the cement clinker obtained in the step (2) at a set temperature, removing residual isopropanol and reducing functional groups in graphene oxide to obtain the cement clinker with the surface coated with graphene, namely the high-heat-conductivity cement clinker.

As a further technical scheme, in the step (1), the sheet diameter of the graphene oxide is 0.1-10 μm, the oxygen content is 20-45%, and the number of layers is 1-10.

As a further technical scheme, in the step (1), the ultrasonic power is 300- & lt1800W ], the frequency is 40-200KHz, and the ultrasonic time is 10-200 min.

As a further technical scheme, in the step (1), the content of the graphene oxide in the dispersion liquid is 0.1-1.2 mg/ml.

As a further technical solution, in the step (2), the cement clinker includes any one of silicate, aluminate, sulphoaluminate, ferrite, phosphate, and the like.

As a further technical scheme, in the step (2), the cement clinker powder can be obtained by crushing the blocky cement clinker, such as mechanical grinding, manual grinding and the like.

As a further technical scheme, in the step (2), the particle size of the cement clinker powder is 300-800 μm.

As a further technical scheme, in the step (2), the addition amount of the graphene oxide-isopropanol dispersion liquid is as follows: the mass of the graphene oxide is 0.5-1.5% of that of the cement clinker.

As a further technical scheme, in the step (2), the sign that all the graphene oxide is adsorbed to the surface of the cement clinker is that the color of the dispersion (low concentration is light yellow, high concentration is reddish brown) disappears.

As a further technical scheme, in the step (2), the implementation manner of the feed liquid separation includes natural sedimentation, filtration and the like.

As a further technical scheme, in the step (3), the temperature is 150-350 ℃, and the time is 3-5 h; annealing at 250 ℃ for 4h is preferred. The annealing temperature has great influence on the reduction degree of the graphene oxide and the form of the graphite oxide on the surface of the cement; the research shows that: when the temperature is lower than 150 ℃, the graphene oxide cannot be completely reduced, and the graphene oxide has poor thermal conductivity and cannot achieve the purpose of improving the thermal conductivity of cement; when the temperature reaches above 350 ℃, the carbon skeleton of part of graphene oxide on the surface of cement particles is damaged, so that the heat-conducting property of the cement particles is reduced; the graphene oxide is reduced most thoroughly at 250 ℃, surface functional groups are removed completely, and the obtained cement has excellent heat-conducting property.

The preparation method of the high heat-conducting cement clinker is characterized by comprising the following steps: the aim of uniformly mixing the graphene oxide and the cement clinker is fulfilled by utilizing the adsorbability between the graphene oxide and the cement clinker in the solution; then, through annealing, on one hand, graphene oxide can be reduced into graphene with high heat conductivity coefficient, and meanwhile, the graphene can be anchored on the surface of clinker, so that the firmness of combination between the graphene oxide and the clinker is enhanced, and the problem that the graphene is easy to fall off when being adsorbed on the surface of a material is solved; this is because: in the annealing process, along with the gradual disappearance of graphene functional groups, atoms on the surface of cement clinker tend to fill the defects on the surface of graphene, so that the graphene and the clinker are tightly combined together, namely the graphene is anchored on the surface of the clinker.

Secondly, the invention discloses a preparation method of a high-thermal-conductivity cement product, which comprises the following steps: the high-thermal-conductivity cement clinker, the gypsum and the mixed material are compounded to obtain the high-thermal-conductivity cement.

As a further technical scheme, the gypsum is dihydrate gypsum, and the doping amount of the dihydrate gypsum accounts for 3-8% of the mass of the high-thermal-conductivity cement product.

As a further technical scheme, the mixed material comprises fly ash, slag and the like, and the mixing amount of the mixed material accounts for 10-35% of the mass of the high-thermal-conductivity cement product.

As a further technical scheme, the particle size of the high thermal conductivity cement product is 0.1-80 μm.

Finally, the invention discloses the application of the high-heat-conductivity cement clinker and the preparation method of the cement product thereof in the field of buildings.

Compared with the prior art, the invention has the following beneficial effects:

(1) the cement product prepared by the invention meets the requirements of high strength and high thermal conductivity, and simultaneously, no substances such as a dispersing agent and the like are added, so that the problem of adaptability of an additional substance and a cement matrix is solved.

(2) According to the invention, graphene oxide is uniformly dispersed in an isopropanol solution by means of an ultrasonic technology, and the graphene oxide can be uniformly attached to the surface of cement clinker particles by taking the isopropanol solution as a medium and adopting a physical adsorption mode.

(3) The graphene oxide can be reduced through annealing treatment, and graphene with high thermal conductivity is obtained. In addition, the boiling point of the isopropanol is low, the isopropanol can be completely volatilized in the annealing process, and the problem of adaptability to cement products does not exist.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms also are intended to include the plural forms as well, unless the context clearly indicates otherwise, and it should be further understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, devices, components, and/or combinations thereof.

As described above, although there have been many studies to introduce graphene into cement-based materials to improve the thermal properties of the cement-based materials by using the excellent thermal conductivity of graphene, there still remain many problems to be solved. Therefore, the invention provides a preparation method and application of the high-heat-conductivity cement clinker and a cement product thereof; the invention will now be further described with reference to specific embodiments.

Example 1

1. A preparation method of high-heat-conductivity cement clinker comprises the following steps:

(1) grinding ordinary portland cement clinker (PO 42.5) by a disc mill to a particle size within the range of 300-;

(2) taking graphene oxide with the sheet diameter of 4-6 microns, the oxygen content of 30% and 1-5 layers, adding the graphene oxide into isopropanol, and performing ultrasonic dispersion for 30min under the conditions of ultrasonic power of 300W and frequency of 200KHz to obtain uniformly dispersed graphene oxide-isopropanol dispersion liquid, wherein the content of the graphene oxide is 0.1mg/ml for later use;

(3) slowly adding the Portland cement clinker ground in the step (1) into the graphene oxide-isopropanol dispersion liquid obtained in the step (2), wherein the adding time is controlled within 10min, and the mass of the added graphene oxide is 0.5% and 1% of that of the cement clinker respectively; then mixing by adopting a magnetic stirring mode, controlling the stirring speed at 200rpm/min, stirring for 12h, basically adsorbing the graphene oxide on the surface of the cement clinker after stirring is finished, and basically enabling the upper surface of the dispersion liquid to be transparent; separating the feed liquid in a filtering mode to obtain cement clinker with the surface coated with graphene oxide;

(4) and (4) putting the cement clinker which is obtained in the step (3) and coated with the graphene oxide on the surface into a drying oven, and annealing at 150 ℃ for 4 hours. And (3) grinding and mixing 75g of cement clinker obtained through annealing treatment, 5g of dihydrate gypsum and 20g of fly ash in a planetary mill for 60min, and then screening by using a 200-mesh standard screen, wherein the cement under the screen is taken to be the high-heat-conductivity cement product.

2. And (3) performance testing:

50g and 25g of water of the highly thermally conductive cement product prepared in this example were taken, stirred and molded by a slurry stirrer, and the thermal conductivity and thermal diffusivity were measured after curing for 28 days. Meanwhile, only cement clinker (no graphene is added in isopropanol) is prepared into a hot cement product as a control group according to the steps. The results of testing the performance of the three sets of cementitious products obtained in this example are shown in table 1.

TABLE 1

From the test results obtained in table 1, it can be seen that: after the graphene is added, the heat conductivity coefficient and the heat diffusion coefficient of the cement are obviously improved. As the doping amount of the graphene is increased, the thermal property of the graphene is improved. When the graphene doping amount is 1%, compared with a control group, the thermal conductivity coefficient of the cement is improved by 41.07%, and the thermal diffusion coefficient is improved by 45.9%. The graphene is uniformly dispersed on the surface of the cement particles, a good heat conducting network is formed in the cement matrix, and the heat transfer speed in the hardened cement stone matrix is increased. The above data demonstrate that the cement product prepared by the present invention has excellent thermal conductivity.

Example 2

(2) taking graphene oxide with the sheet diameter of 4-6 microns, the oxygen content of 30% and 1-5 layers, adding the graphene oxide into isopropanol, and performing ultrasonic dispersion for 30min under the conditions of ultrasonic power of 300W and frequency of 200KHz to obtain uniformly dispersed graphene oxide-isopropanol dispersion liquid, wherein the content of the graphene oxide is 0.1 mg/ml;

(3) slowly adding the Portland cement clinker ground in the step (1) into the graphene oxide-isopropanol dispersion liquid obtained in the step (2), wherein the adding time is controlled within 10min, and the mass of the added graphene oxide is 1% of that of the cement clinker; and then mixing by adopting a magnetic stirring mode, controlling the stirring speed at 200rpm/min, stirring for 12h, completely adsorbing all graphene oxide on the surface of the cement clinker after stirring is finished, and basically enabling the upper surface of the dispersion liquid to be transparent. Then, obtaining the cement clinker with the surface coated with the graphene oxide in a filtering mode;

(4) and (4) putting the cement clinker which is obtained in the step (3) and coated with the graphene oxide on the surface into a drying box, and annealing at 150 ℃, 250 ℃ and 350 ℃ for 4 hours respectively. And taking 75g of the cement clinker, 5g of dihydrate gypsum and 20g of fly ash obtained by the treatment, fully grinding and mixing in a planetary mill for 60min, and screening by using a 200-mesh standard screen after grinding, wherein the cement under the screen is the high-heat-conductivity cement product.

2. And (3) performance testing:

50g and 25g of water were taken from the highly thermally conductive cement product prepared in this example, and stirred and molded with a mortar mixer, and the thermal conductivity and thermal diffusivity were measured after curing for 28 days, and the results are shown in Table 2.

TABLE 2

From the test results obtained in table 2, it can be seen that: the annealing temperature has a significant influence on the thermal properties of the graphene-cement material. The effect is optimal with an annealing temperature of 250 c, followed by an annealing temperature of 150 c, and the worst thermal performance is an annealing temperature of 350 c. This is due to the different degree of reduction of graphene oxide by the annealing temperature. The graphene oxide is reduced most thoroughly at 250 ℃, surface functional groups are removed completely, and the graphene has high heat conductivity coefficient, so that the cement has the best heat conductivity. At 350 ℃, the carbon skeleton of part of graphene oxide is damaged, and the heat conductivity of the graphene oxide is reduced, so that the thermal performance of the cement is reduced.

Example 3

(1) grinding ordinary portland cement clinker (PO 42.5) by a disc mill until the particle size is within the range of 500-;

(2) taking graphene oxide with the sheet diameter of 0.1-4 mu m, the oxygen content of 20% and 4-10 layers, adding the graphene oxide into isopropanol, and performing ultrasonic dispersion for 200min under the conditions of ultrasonic power of 1000W and frequency of 100KHz to obtain uniformly dispersed graphene oxide-isopropanol dispersion liquid, wherein the content of the graphene oxide is 1.2 mg/ml;

(3) slowly adding the Portland cement clinker ground in the step (1) into the graphene oxide-isopropanol dispersion liquid obtained in the step (2), wherein the adding time is controlled within 10min, and the mass of the added graphene oxide is 1.5% of that of the cement clinker; and then mixing by adopting a magnetic stirring mode, controlling the stirring speed at 250rpm/min, stirring for 12h, completely adsorbing all graphene oxide on the surface of the cement clinker after stirring is finished, and basically enabling the upper surface of the dispersion liquid to be transparent. Then, obtaining the cement clinker with the surface coated with the graphene oxide in a filtering mode;

(4) and (4) putting the cement clinker which is obtained in the step (3) and coated with the graphene oxide on the surface into a drying box, and respectively carrying out annealing treatment at 250 ℃ for 3 hours. And (3) taking 82g of the cement clinker, 8g of dihydrate gypsum and 10g of fly ash obtained by the treatment, fully grinding and mixing in a planetary mill for 60min, and screening by using a 200-mesh standard screen after grinding, wherein the cement under the screen is the high-heat-conductivity cement product.

2. And (3) performance testing:

50g and 25g of water were taken from the highly thermally conductive cement product prepared in this example, and stirred and molded with a mortar mixer, and the thermal conductivity and thermal diffusivity were measured after curing for 28 days (test group). Meanwhile, 50g of the cement clinker prepared in step (3) of this example and 25g of water were mixed and molded with a paste mixer, and the thermal conductivity and thermal diffusivity were measured after curing for 28 days, as a control. The results of testing the performance of the three sets of cementitious products obtained in this example are shown in table 3.

TABLE 3

Example 4

(2) taking graphene oxide with the sheet diameter of 5-10 mu m, the oxygen content of 45% and 6-9 layers, adding the graphene oxide into isopropanol, and performing ultrasonic dispersion for 10min under the conditions that the ultrasonic power is 1800W and the frequency is 40KHz to obtain uniformly dispersed graphene oxide-isopropanol dispersion liquid, wherein the content of the graphene oxide is 0.8 mg/ml;

(3) slowly adding the Portland cement clinker ground in the step (1) into the graphene oxide-isopropanol dispersion liquid obtained in the step (2), wherein the adding time is controlled within 10min, and the mass of the added graphene oxide is 1.2% of that of the cement clinker; and then mixing by adopting a magnetic stirring mode, controlling the stirring speed at 250rpm/min, stirring for 12h, completely adsorbing all graphene oxide on the surface of the cement clinker after stirring is finished, and basically enabling the upper surface of the dispersion liquid to be transparent. Then, obtaining the cement clinker with the surface coated with the graphene oxide in a filtering mode;

(4) and (4) putting the cement clinker which is obtained in the step (3) and coated with the graphene oxide on the surface into a drying box, and respectively carrying out annealing treatment at 250 ℃ for 5 hours. And (3) taking 62g of the cement clinker, 3g of dihydrate gypsum and 35g of fly ash obtained by the treatment, fully grinding and mixing in a planetary mill for 60min, and screening by using a 200-mesh standard screen after grinding, wherein the screened cement is the high-heat-conductivity cement product.

2. And (3) performance testing:

50g and 25g of water were taken from the highly thermally conductive cement product prepared in this example, and stirred and molded with a mortar mixer, and the thermal conductivity and thermal diffusivity were measured after curing for 28 days (test group). Meanwhile, 50g of the cement clinker prepared in step (3) of this example and 25g of water were mixed and molded with a paste mixer, and the thermal conductivity and thermal diffusivity were measured after curing for 28 days, as a control. The results of testing the properties of the three sets of cementitious products obtained in this example are shown in table 4.

TABLE 4

As can be seen from the test results of tables 3 and 4: the annealing treatment has obvious influence on the prepared heat-conducting cement clinker, and the heat-conducting property of the cement is obviously improved after the annealing treatment at different time, because the graphene oxide can be reduced into the graphene with high heat-conducting coefficient by the over-annealing treatment, so that the heat-conducting property of the cement product is improved.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The preparation method of the high-heat-conductivity cement clinker is characterized by comprising the following steps of:

(1) ultrasonically dispersing graphene oxide into isopropanol to obtain a graphene oxide-isopropanol dispersion liquid for later use;

(3) annealing the cement clinker obtained in the step (2) at a set temperature, and removing functional groups in residual isopropanol and graphene oxide to obtain the cement clinker with the surface coated with graphene, namely the high-heat-conductivity cement clinker; wherein the annealing temperature is 150-350 ℃, and the annealing time is 3-5 h.

2. The method for preparing the cement clinker with high thermal conductivity according to claim 1, wherein in the step (1), the graphene oxide has a sheet diameter of 0.1-10 μm, an oxygen content of 20-45%, and a number of layers of 1-10.

3. The method for preparing cement clinker as claimed in claim 1, wherein in step (1), the ultrasonic power is 300- & lt1800W, the frequency is 40-200KHz, and the ultrasonic time is 10-200 min.

4. The method for preparing the highly heat-conductive cement clinker according to claim 1, wherein in the step (1), the content of the graphene oxide in the dispersion is 0.1-1.2 mg/ml.

5. The method for preparing high thermal conductivity cement clinker according to claim 1, wherein in step (2), the cement clinker comprises any one of silicate, aluminate, sulphoaluminate, ferrite and phosphate.

6. The method for preparing cement clinker with high thermal conductivity as claimed in claim 1, wherein in the step (2), the cement clinker powder is obtained by crushing massive cement clinker.

7. The method for preparing high thermal conductivity cement clinker as claimed in claim 1, wherein in step (2), the particle size of the cement clinker powder is 300-800 μm.

8. The method for preparing cement clinker with high thermal conductivity according to claim 1, wherein in the step (2), the sign that all of the graphene oxide is adsorbed on the surface of the cement clinker is that the color of the dispersion liquid disappears.

9. The method for preparing highly heat-conductive cement clinker according to claim 1, wherein in the step (2), the separation of the feed liquid is performed by natural sedimentation or filtration.

10. The method for preparing cement clinker with high thermal conductivity as claimed in claim 1, wherein in step (3), annealing is carried out at 250 ℃ for 4 hours.

11. A preparation method of a high-thermal-conductivity cement product is characterized by comprising the following steps: compounding the high thermal conductivity cement clinker prepared by the method of any one of claims 1 to 10, gypsum and a mixed material to obtain the cement.

12. The method of claim 11, wherein the gypsum is dihydrate gypsum and is added in an amount of 3-8% by mass of the highly thermally conductive cement product.

13. The method according to claim 11, wherein the admixture comprises one or both of fly ash and slag in an amount of 10 to 35% by mass based on the mass of the highly thermally conductive cement product.

14. The method according to claim 11, wherein the highly thermally conductive cement product has a particle size of 0.1 to 80 μm.

15. Use of a highly thermally conductive cement clinker prepared by the process for the preparation of a highly thermally conductive cement clinker according to any one of claims 1 to 10 or a highly thermally conductive cement product prepared by the process for the preparation of a highly thermally conductive cement product according to any one of claims 11 to 14 in the field of construction.