Electrically conductive cementitious composite material and method of making and use thereof

Abstract

The application discloses a conductive cement-based composite material and a preparation method and application thereof. The conductive cement-based composite material comprises the following components in mass parts: cementing material: 100 parts; fine aggregate: 150-450 parts; conductive hydrogel dry powder: 0.1-2 parts; water reducing agent: 0.5-5 parts. The preparation method of the conductive cement-based composite material comprises the following steps: 1) uniformly mixing the conductive hydrogel dry powder and the cementing material to prepare a mixture, and dissolving the water reducing agent in water to prepare a water reducing agent solution; 2) uniformly mixing the water reducing agent solution into the mixture, then uniformly mixing the fine aggregate, then injecting a mold for forming, then demolding and curing, so that the conductive cement-based composite material is obtained. The conductive cement-based composite material has excellent conductive performance and excellent mechanical performance, and the preparation method is simple, the production cost is low, and the conductive cement-based composite material is suitable for large-scale popularization and application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a conductive cement-based composite material and a preparation method and application thereof. BACKGROUND

[0002] Cement-based materials have excellent mechanical properties, simple preparation process and other advantages, and are the most widely used basic building materials at present. With the changes in economy and social needs, the intelligentization of cement-based materials is increasingly valued. Research has found that the electrical conductivity of cement-based materials is the prerequisite for developing functions such as sensitivity and thermal sensitivity of cement-based materials.

[0003] At present, the electrical conductivity of cement-based materials is mainly realized by introducing conductive fillers (for example: metal-based conductive materials represented by steel fibers and steel shavings; carbon-based conductive materials such as carbon nanotubes, carbon fibers, graphite powder, and carbon black). On the one hand, direct contact between conductive fillers will form a conductive path to ensure the passage of an external current. On the other hand, when the conductive fillers are not in direct contact, electrons can pass through the hydration products between the conductive fillers through tunneling effect, thereby realizing the electrical conductivity of cement-based materials. Therefore, in order to ensure the formation of a conductive path between fillers or a small enough distance between conductive fillers, there is a lower limit to the amount of conductive fillers, below which the electrical conductivity of cement-based materials cannot be significantly improved. However, due to the significant differences in composition and density between conductive fillers and cement-based materials, cement-based composites are prone to uneven dispersion or even agglomeration of conductive fillers during the preparation process. In order to build a conductive path, the lower limit of the amount of conductive fillers needs to be further improved, and the compatibility between conductive fillers and the cement matrix is poor, so that an excessively high amount of conductive fillers will significantly reduce the mechanical properties of cement-based composites, making it difficult to fully meet the requirements of practical applications.

[0004] Therefore, it is of great significance to develop a cement-based composite material that has excellent electrical conductivity and excellent mechanical properties. SUMMARY

[0005] The purpose of the present application is to provide a conductive cement-based composite material and a preparation method and application thereof.

[0006] The technical solution adopted by the present application is as follows:

[0007] A conductive cement-based composite material, which comprises the following components by mass:

[0008] Cementitious material: 100 parts;

[0009] Fine aggregate: 150-450 parts;

[0010] Conductive hydrogel dry powder: 0.1-2 parts;

[0011] Water reducing agent: 0.5-5 parts.

[0012] Preferably, the cementitious material is Portland cement or a mixture of Portland cement and at least one of blast furnace slag, steel slag, fly ash, and limestone powder.

[0013] Preferably, the fine aggregate is at least one of natural sand and machine-made sand.

[0014] Preferably, the fine aggregate has a particle size of 0.075-4.75 mm.

[0015] Preferably, the composition of the conductive hydrogel dry powder comprises a base organic polymer, a conductive organic polymer, and inorganic conductive microparticles.

[0016] Preferably, the mass ratio of the base organic polymer, the conductive organic polymer, and the inorganic conductive microparticles is 1:0.05-0.2:0.2-0.4.

[0017] Preferably, the base organic polymer is at least one of polyacrylamide, polyacrylic acid, and polyvinyl alcohol.

[0018] Preferably, the conductive organic polymer is at least one of polythiophene, polyaniline, and polypyrrole. By using the conductive organic polymer and the base organic polymer to construct the conductive hydrogel, a conductive polymer network is formed, and the use of inorganic conductive particles as nodes can further reduce the resistivity of the conductive network, thereby achieving efficient construction of a conductive path.

[0019] Preferably, the inorganic conductive microparticles are one of graphite powder and carbon black powder. The graphite powder and the carbon black powder can serve as physical crosslinking centers of the hydrogel, which can increase the mechanical properties and density of the conductive hydrogel, reduce the difference in properties from the cement matrix, thereby improving compatibility, and also help the partial shedding of the conductive hydrogel polymer in the pore solution environment, which can be further dispersed under mechanical stirring.

[0020] Preferably, the inorganic conductive microparticles have an average particle size of 2-10 μm.

[0021] Preferably, the conductive hydrogel dry powder has a particle size of 10-30 μm.

[0022] Preferably, the conductive hydrogel dry powder is prepared by the following method: dissolving a conductive organic polymer monomer in water to obtain a conductive organic polymer monomer solution, adding a base organic polymer monomer to the conductive organic polymer monomer solution under stirring to obtain a hydrogel precursor solution, adding inorganic conductive microparticles and an initiator to perform a crosslinking reaction, and then drying and pulverizing to obtain the conductive hydrogel dry powder.

[0023] Preferably, the initiator is at least one of potassium persulfate, ammonium persulfate, ferrous sulfate, sodium bisulfite.

[0024] Preferably, the water reducing agent is a polycarboxylic acid water reducing agent.

[0025] Preferably, the electrically conductive cement-based composite material has a 28-day resistivity of 1.5Ω·m to 4.5Ω·m and a 28-day compressive strength of 40MPa to 60MPa.

[0026] A method for preparing an electrically conductive cement-based composite material as described above comprises the following steps:

[0027] 1) mixing the electrically conductive hydrogel dry powder and the cementitious material to obtain a mixture, and dissolving the water reducing agent in water to obtain a water reducing agent solution;

[0028] 2) adding the water reducing agent solution to the mixture and mixing, then adding the fine aggregate and mixing, then injecting the mold for molding, then demolding and curing, to obtain the electrically conductive cement-based composite material.

[0029] Preferably, a method for preparing an electrically conductive cement-based composite material as described above comprises the following steps:

[0030] 1) mixing the electrically conductive hydrogel dry powder and the cementitious material to obtain a mixture, and dissolving the water reducing agent in water to obtain a water reducing agent solution;

[0031] 2) adding the water reducing agent solution to the mixture and mixing, then adding the fine aggregate and mixing, then injecting the mold for molding, then demolding and curing, to obtain the electrically conductive cement-based composite material.

[0032] An electrically conductive cement-based composite material as described above is used in the preparation of an external anode of a cathodic protection system.

[0033] The principle of the present application: the present application introduces an inorganic conductive microparticle-conductive polymer composite conductive hydrogel, uses the high ion concentration in the pore solution environment to promote the shedding and secondary dispersion of part of the polymer, and constructs conductive paths of different scales through inorganic conductive microparticles and conductive polymers. At the same time, based on the active shedding and self-dispersion of the conductive polymer, the polymer is redistributed in the freshly mixed cement-based material, thereby improving the uniformity of the distribution of the conductive filler. In addition, since the functional groups on the surface of the conductive polymer can form chemical bonds with the hydration products through hydrogen bonding or chelation, the compatibility with the cement matrix is also improved, and finally a cement-based composite material with excellent electrical conductivity and excellent mechanical properties can be obtained.

[0034] The conductive cement-based composite material has excellent electrical conductivity and mechanical properties, and the preparation method is simple, the production cost is low, and the conductive cement-based composite material is suitable for large-scale popularization and application.

[0035] Specifically,

[0036] 1) The conductive cement-based composite material of the present application adds conductive hydrogel, which can completely avoid the risk of corrosion compared with metal-based conductive fillers;

[0037] 2) The conductive hydrogel added in the conductive cement-based composite material of the present application comprises inorganic conductive microparticles and conductive organic polymers, which can construct a multi-scale conductive path, that is, the conductive organic polymer network can form a direct path, and the inorganic conductive microparticles as nodes can enhance the conductivity of the network;

[0038] 3) The hydrogel polymerization and crosslinking process of the conductive hydrogel added in the conductive cement-based composite material of the present application has been completed before being introduced into the cement-based material, which does not affect the hydration of cement, and the surface of the conductive hydrogel is rich in hydroxyl groups, carboxyl groups and other groups, which can be combined with the cement matrix through hydrogen bond chelation to realize stable combination;

[0039] 4) The uniform dispersion of the conductive organic polymer in the conductive cement-based composite material of the present application helps to directly form a conductive network, which can reduce the amount of conductive filler required for the conductivity of the cement-based material, and has little negative effect on the strength of the cement-based material. DETAILED DESCRIPTION

[0040] The present application will be further explained and described below in conjunction with specific examples.

[0041] Example 1:

[0042] A conductive cement-based composite material, the composition of which is shown in the following table:

[0043] Table 1 Composition of a conductive cement-based composite material

[0044]

[0045]

[0046] Note:

[0047] Cementitious material: Portland cement, strength grade 52.5R.

[0048] The conductive hydrogel dry powder is prepared by the following method: dissolving 0.2 g of pyrrole in 50 mL of deionized water at room temperature to prepare a pyrrole solution, adding 1 g of acrylamide to the stirring pyrrole solution to prepare a hydrogel precursor solution, then adding 0.2 g of graphite powder with an average particle size of 5 μm and 0.06 g of ammonium persulfate, and then reacting at a temperature of 55℃ for 2 h, followed by drying and pulverization to obtain the conductive hydrogel dry powder.

[0049] The preparation method of the conductive cement-based composite material is as follows:

[0050] 1) The conductive hydrogel dry powder and the cementitious material are stirred and mixed for 1 min to prepare a mixture, and the polycarboxylic acid water reducing agent is dissolved in water (the amount of water is 40% of the weight of the cementitious material) to prepare a water reducing agent solution;

[0051] 2) The water reducing agent solution is added to the mixture and stirred and mixed for 3 min, then natural sand is added and stirred and mixed for 2 min, then the mold is injected for molding, and then demolding is performed for curing (stirring, molding, demolding and curing are performed according to “GB / T 17671-2021 Cement Mortar Strength Test Method”).

[0052] Performance test:

[0053] It is tested that the 28-day resistivity of the conductive cement-based composite material of the embodiment is 4.2 Ω·m, and the 28-day compressive strength is 58 MPa.

[0054] Note:

[0055] Resistivity: tested according to “GB / T 1692-2008 Determination of Insulation Resistivity of Vulcanized Rubber”.

[0056] Compressive strength: tested according to “GB / T 17671-2021 Cement Mortar Strength Test Method”.

[0057] Example 2:

[0058] A conductive cement-based composite material, the composition of which is shown in the following table:

[0059] Table 2 Composition of a conductive cement-based composite material

[0060]

[0061]

[0062] Note:

[0063] Cementitious material: mixed by silicate cement (strength grade 42.5R), steel slag (particle size 5-30 μm) and fly ash (particle size 3-15 μm) according to the mass ratio of 60:20:20.

[0064] The conductive hydrogel dry powder is prepared by the following method: dissolving 0.15 g of pyrrole in 50 mL of deionized water at room temperature to prepare a pyrrole solution, adding 1 g of acrylic acid to the stirring pyrrole solution to prepare a hydrogel precursor solution, adding 0.3 g of carbon black powder with an average particle size of 8 μm and 0.06 g of ammonium persulfate, and then reacting at a temperature of 65 ℃ for 3 h, followed by drying and pulverizing to obtain the conductive hydrogel dry powder.

[0065] The preparation method of the above conductive cement-based composite material is as follows:

[0066] 1) The conductive hydrogel dry powder and the cementitious material are stirred and mixed for 1.5 min to prepare a mixture, and the polycarboxylic acid water reducing agent is dissolved in water (the amount of water is 50% of the weight of the cementitious material) to prepare a water reducing agent solution;

[0067] 2) The water reducing agent solution is added to the mixture and stirred and mixed for 4 min, then machine-made sand is added and stirred and mixed for 2 min, then the mold is injected for molding, and then demolding is performed for curing (stirring, molding, demolding and curing are performed according to “GB / T 17671-2021 Cement Mortar Strength Test Method”).

[0068] Performance test (test method same as example 1):

[0069] It is tested that the 28-day resistivity of the conductive cement-based composite material of the embodiment is 2.3 Ω·m, and the 28-day compressive strength is 45 MPa.

[0070] Example 3:

[0071] A conductive cement-based composite material, the composition of which is shown in the following table:

[0072] Table 3 Composition table of a conductive cement-based composite material

[0073]

[0074]

[0075] Note:

[0076] Cementitious material: silicate cement, strength grade 42.5R.

[0077] The conductive hydrogel dry powder is prepared by the following method: 0.4 g of aniline is dissolved in 50 mL of deionized water at room temperature to prepare an aniline solution, 2 g of acrylic acid is added to the stirring aniline solution to prepare a hydrogel precursor solution, 0.4 g of graphite powder with an average particle size of 4 μm and 0.06 g of ammonium persulfate are added, and then the mixture is reacted at a temperature of 60℃ for 2 h, followed by drying and pulverization to obtain the conductive hydrogel dry powder.

[0078] The preparation method of the conductive cement-based composite material is as follows:

[0079] 1) The conductive hydrogel dry powder and the cementitious material are stirred and mixed for 1 min to prepare a mixture, and the polycarboxylic acid water reducing agent is dissolved in water (the amount of water is 40% of the weight of the cementitious material) to prepare a water reducing agent solution;

[0080] 2) The water reducing agent solution is added to the mixture and stirred and mixed for 4 min, then natural sand is added and stirred and mixed for 2 min, then the mixture is poured into a mold for molding, and then demolding and curing are performed (stirring, molding, demolding and curing are performed according to “GB / T 17671-2021 Cement Mortar Strength Test Method”), to obtain the conductive cement-based composite material.

[0081] Performance test (test method same as example 1):

[0082] It is tested that the 28-day resistivity of the conductive cement-based composite material of the present embodiment is 4.4 Ω·m, and the 28-day compressive strength is 53 MPa.

[0083] Example 4:

[0084] A conductive cement-based composite material, the composition of which is shown in the following table:

[0085] Table 4 Composition table of a conductive cement-based composite material

[0086]

[0087] Note:

[0088] Cementitious material: mixed by silicate cement (strength grade 42.5R), steel slag (particle size 5 μm-30 μm) and fly ash (particle size 3 μm-15 μm) in a mass ratio of 60:20:20.

[0089] The conductive hydrogel dry powder is prepared by the following method: 0.4 g of pyrrole is dissolved in 50 mL of deionized water at room temperature to prepare a pyrrole solution, 2 g of polyvinyl alcohol powder is added to the stirring pyrrole solution to prepare a hydrogel precursor solution, 0.5 g of carbon black powder with an average particle size of 5 μm and 0.06 g of ammonium persulfate are added, and then the mixture is reacted at a temperature of 50℃ for 4 h, followed by drying and pulverization to obtain the conductive hydrogel dry powder.

[0090] The preparation method of the conductive cement-based composite material is as follows:

[0091] 1) The conductive hydrogel dry powder and the cementitious material are stirred and mixed for 2 min to prepare a mixture, and the polycarboxylic acid water reducing agent is dissolved in water (the amount of water is 50% of the weight of the cementitious material) to prepare a water reducing agent solution;

[0092] 2) The water reducing agent solution is added to the mixture and stirred and mixed for 3.5 min, then the machine-made sand is added and stirred and mixed for 3 min, then the mold is injected for molding, and then the mold is demolded and cured (the stirring, molding, demolding and curing are carried out according to "GB / T 17671-2021 Cement Mortar Strength Test Method"), to obtain the conductive cement-based composite material.

[0093] Performance test (test method same as example 1):

[0094] It is tested that the 28-day resistivity of the conductive cement-based composite material of the embodiment is 1.8 Ω·m, and the 28-day compressive strength is 42 MPa.

[0095] Example 5:

[0096] A conductive cement-based composite material, the composition of which is shown in the following table:

[0097] Table 5 Composition table of a conductive cement-based composite material

[0098]

[0099] Note:

[0100] Cementitious material: mixed by silicate cement (strength grade 42.5R), steel slag (particle size 5 μm-30 μm) and fly ash (particle size 3 μm-15 μm) according to the mass ratio of 60:20:20.

[0101] The conductive hydrogel dry powder is prepared by the following method: 0.3 g of thiophene is dissolved in 50 mL of deionized water to prepare a thiophene solution at room temperature, 2 g of acrylamide is added to the stirring thiophene solution to prepare a hydrogel precursor solution, 0.6 g of graphite powder with an average particle size of 6 μm and 0.06 g of ammonium persulfate are added, and then the mixture is reacted at a temperature of 70℃ for 1.5 h, followed by drying and pulverization to obtain the conductive hydrogel dry powder.

[0102] The preparation method of the conductive cement-based composite material is as follows:

[0103] 1) The conductive hydrogel dry powder and the cementitious material are stirred and mixed for 1 min to prepare a mixture, and the polycarboxylic acid water reducing agent is dissolved in water (the amount of water is 35% of the weight of the cementitious material) to prepare a water reducing agent solution;

[0104] 2) The water reducing agent solution is added to the mixture and stirred and mixed for 3 min, then the machine-made sand is added and stirred and mixed for 2 min, then the mold is injected for molding, and then the mold is demolded and cured (the stirring, molding, demolding and curing are carried out according to “GB / T 17671-2021 Cement Mortar Strength Test Method”), to obtain the conductive cement-based composite material.

[0105] Performance test (test method same as example 1):

[0106] It is tested that the 28-day resistivity of the conductive cement-based composite material of the present embodiment is 2.7 Ω·m, and the 28-day compressive strength is 59 MPa.

[0107] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. An electrically conductive cementitious composite material, characterized by, The composition comprises the following components by mass: Gelled material: 100 parts; Fine aggregate: 150-450 parts; Conductive hydrogel dry powder: 0.1-2 parts; Water reducing agent: 0.5-5 parts; The conductive hydrogel dry powder comprises a base organic polymer, a conductive organic polymer and inorganic conductive microparticles; The mass ratio of the base organic polymer, the conductive organic polymer and the inorganic conductive microparticles is 1:0.05-0.2:0.2-0.4; The particle size of the conductive hydrogel dry powder is 10-30 μm; The conductive hydrogel dry powder is prepared by dissolving conductive organic polymer monomers in water to form a conductive organic polymer monomer solution, adding base organic polymer monomers to the conductive organic polymer monomer solution under stirring to form a hydrogel precursor solution, adding inorganic conductive microparticles and an initiator to perform cross-linking reaction, and then drying and pulverizing to obtain the conductive hydrogel dry powder.

2. The electrically conductive cementitious composite of claim 1, wherein: The gelled material is Portland cement or a mixture of Portland cement and at least one of blast furnace slag, steel slag, fly ash and limestone powder.

3. The electrically conductive cementitious composite of claim 1, wherein: The fine aggregate is at least one of natural sand and machine-made sand.

4. The electrically conductive cementitious composite of claims 1 or 3, wherein: The particle size of the fine aggregate is 0.075-4.75 mm.

5. The electrically conductive cementitious composite of claim 1, wherein: The base organic polymer is at least one of polyacrylamide, polyacrylic acid and polyvinyl alcohol; the conductive organic polymer is at least one of polythiophene, polyaniline and polypyrrole; the inorganic conductive microparticles are one of graphite powder and carbon black powder; and the average particle size of the inorganic conductive microparticles is 2-10 μm.

6. A method of producing the electrically conductive cement-based composite material according to any one of claims 1 to 5, characterized by, The method comprises the following steps: 1) mixing the conductive hydrogel dry powder and the gelled material to form a mixture, dissolving the water reducing agent in water to form a water reducing agent solution; 2) adding the water reducing agent solution to the mixture, mixing, adding the fine aggregate, mixing, pouring into a mold, demolding, curing, and obtaining the conductive cement-based composite material.

7. Use of the conductive cement-based composite material of any one of claims 1-5 in preparing an external anode of a cathodic protection system.

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