A protective coating material for cement-based steel reinforcement containing C7MS4-C5MS3 phosphoaluminate, its preparation method, and its application.

Abstract

This invention relates to a protective coating material for reinforcing bars based on C7MS4-C5MS3 phosphoaluminate cement, its preparation method, and its application, belonging to the field of civil engineering technology. This invention utilizes organic binders, emulsifying stabilizers, dispersants, and early-strength agents combined with inorganic cementitious materials such as iron-rich phosphoaluminate cement containing the C7MS4-C5MS3 mineral phase to prepare a reinforcing bar coating material that is easy to apply, has strong adhesion, and high durability. This reinforcing bar coating material is mainly suitable for corrosion prevention of reinforcing bars in marine environments. The reinforcing bar coating material prepared by combining organic and inorganic materials exhibits strong adhesion, high resistance to erosion and carbonation, and a dense structure, solving the problems of poor adhesion and easy peeling of traditional inorganic coating materials. Furthermore, the reinforcing bar coating material prepared by combining organic and inorganic materials can significantly improve the corrosion resistance of reinforcing bars in reinforced concrete, extending the service life of the reinforcing bars.

Description

Technical Field

[0001] This invention relates to a protective coating material for cement-based steel reinforcement containing C7MS4-C5MS3 phosphoaluminate, its preparation method, and its application, belonging to the field of civil engineering technology. Background Technology

[0002] In reinforced concrete structures, steel bars bear the primary load-bearing load. However, in humid, acidic, or alkaline environments, these steel bars are susceptible to corrosion, leading to the destruction of the concrete structure. To extend the service life of concrete structures and protect steel bars from corrosion, anti-corrosion coating technology for steel bars has emerged.

[0003] The development of anti-corrosion coating technology for reinforcing bars has gone through several stages. Initially, natural materials such as asphalt or paraffin were used to protect reinforcing bars from corrosion. These materials had a certain degree of anti-corrosion effect, but problems such as poor adhesion and poor durability existed in long-term use. With the continuous advancement of science and technology, high-performance coatings such as synthetic resin coatings and epoxy resin coatings have gradually become mainstream, possessing good corrosion resistance and adhesion. However, the inherent characteristics of their main organic materials make the application process relatively more complex, and their poor weather resistance makes them susceptible to environmental factors such as ultraviolet radiation, high temperature, and humidity, leading to aging, cracking, or peeling of the coating, thus affecting its anti-corrosion effect.

[0004] In recent years, steel reinforcement anti-corrosion coating technology has also seen new developments. The application of nanotechnology has brought new possibilities to steel reinforcement anti-corrosion coatings. By adding nanomaterials, the corrosion resistance and mechanical properties of the coating can be improved, extending its service life. However, its immature technology can lead to material instability, which may change during long-term use, resulting in performance degradation. Furthermore, some nanomaterials may pose potential risks to the environment and human health. When using nanomaterials, thorough risk assessments and safety measures are necessary to ensure that they do not cause harm to the environment and human health during construction and use. Inorganic phosphoaluminate coating materials have higher compatibility with concrete, resulting in high stability and durability after being applied to steel reinforcement. However, they suffer from poor adhesion between the inorganic phosphoaluminate coating and the steel reinforcement, making them difficult to apply. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a protective coating material for cement-based steel bars containing C7MS4-C5MS3 phosphoaluminate. This material can effectively solve the problem of poor adhesion between phosphate coatings and steel bars. This invention not only provides a strong guarantee for the long-term stable operation of concrete structures, but also promotes the continuous innovation and development of the building coatings industry.

[0006] The present invention also provides a method for preparing the above-mentioned protective coating material for cement-based steel bars containing C7MS4-C5MS3 phosphoaluminate.

[0007] The present invention further provides an application of a protective coating material for cement-based steel reinforcement containing C7MS4-C5MS3 phosphoaluminate.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] This invention provides a protective coating material for cement-based steel reinforcement containing C7MS4-C5MS3 phosphoaluminate, comprising the following components in parts by weight:

[0010] Inorganic cementitious materials: 50-90 parts;

[0011] Adhesive: 8-20 parts;

[0012] Emulsion stabilizer: 1-10 parts;

[0013] Early strength agent: 2-10 parts;

[0014] Dispersant: 1-10 parts;

[0015] Water-reducing agent: 0.1-1 part;

[0016] Water-to-binder ratio: 0.23–0.38 parts.

[0017] Furthermore, the inorganic cementitious material comprises the following components in parts by weight:

[0018] Phosphoaluminate cement containing C7MS4-C5MS3 mineral phase: 65-85 parts;

[0019] Sulfoaluminate cement: 5-10 parts;

[0020] Silicate cement: 20-30 parts.

[0021] Furthermore, the phosphoaluminate cement containing the C7MS4-C5MS3 mineral phase comprises the following system and components:

[0022] Calcium aluminophosphate C8A6P: 20-30%;

[0023] Calcium aluminate phosphate (C(A,P):) 15-20%;

[0024] Ca5(PO4)2SiO4: 20-25%;

[0025] α-type Ca3(PO4)2: 1-10%;

[0026] C4AF: 1-10%;

[0027] C7MS4-C5MS3: 10-20%.

[0028] Furthermore, the C7MS4-C5MS3 mineral phase phosphoaluminate cement comprises the following components:

[0029] Fluoroapatite: 15-20 parts

[0030] Low-grade bauxite: 30-50 parts;

[0031] Low-grade limestone: 30-60 parts;

[0032] Iron powder: 1-10 parts.

[0033] Furthermore, the adhesive is composed of one or more of epoxy resin, styrene-butadiene latex, vinyl acetate and ethylene copolymer powder; preferably, the modulus of the adhesive is 1.0 to 10; most preferably, the mass ratio of epoxy resin, styrene-butadiene latex, vinyl acetate and ethylene copolymer powder in the adhesive is 10 to 20: 70 to 80: 1 to 10.

[0034] Furthermore, the emulsifying stabilizer is composed of one or two of phenolic resin and coumarone resin.

[0035] Furthermore, the dispersant is composed of one or more of sulfonates, fatty alcohol polyoxyethylene ethers, and polyether polyols.

[0036] Furthermore, the early strength agent is composed of one or more of sodium sulfate, triethanolamine, calcium formate, and urea.

[0037] The present invention also provides a method for preparing the above-mentioned protective coating material for cement-based steel bars containing C7MS4-C5MS3 phosphoaluminate, comprising the following steps:

[0038] 1) Weigh the fluorinated apatite, bauxite, low-grade limestone, and iron powder, and calcine them at 1300-1500℃, then rapidly cool, crush, and sieve them to obtain phosphoaluminate cement containing C7MS4-C5MS3 mineral phases.

[0039] 2) Mix the water-reducing agent, dispersant, binder, early-strength agent, emulsifying stabilizer, and water to obtain a mixed liquid;

[0040] 3) Then dry-mix the inorganic cementitious materials;

[0041] 4) Finally, thoroughly stir the well-mixed inorganic cementitious material with the mixed liquid.

[0042] Another objective of this invention is to provide the application of the above-mentioned C7MS4-C5MS3 phosphoaluminate cement-based steel reinforcement protective coating material in steel reinforcement corrosion prevention.

[0043] The strong adhesion and easy-to-apply steel reinforcement coating of the present invention uses C7MS4-C5MS3 phosphoaluminate cement, sulfoaluminate cement, and silicate cement as the matrix, and binders, early strength agents, water-reducing agents, emulsifying stabilizers, and dispersants as modifying additives to make a rust-inhibiting coating with good adhesion to steel reinforcement and easy application during construction.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The C7MS4-C5MS3 phosphoaluminate cement-based steel reinforcement protective coating material of the present invention uses C7MS4-C5MS3 phosphoaluminate cement, sulfoaluminate cement and silicate cement as the matrix. It has excellent corrosion resistance and easy-to-apply properties. Under the synergistic effect of each raw material, the coating material has good substrate adhesion, high mechanical strength and improved coating performance. The obtained anti-rust coating has high hardness, is easy to apply, has strong stability, good adhesion to steel reinforcement, and has good rust protection effect in high concentration of Cl-. The steel reinforcement coating material prepared by the combination of organic and inorganic materials can significantly improve the corrosion resistance of steel reinforcement in reinforced concrete and extend the service life of steel reinforcement.

[0046] (2) This invention uses inorganic materials as the base material, and there is no release of toxic gases, which is environmentally friendly. Therefore, the strong adhesion and easy-to-apply steel reinforcement coating of this invention has the development potential of green and pollution-free steel reinforcement coating.

[0047] (3) This invention also provides the application of C7MS4-C5MS3 phosphoaluminate cement-based coating material in the corrosion prevention of reinforcing steel bars. A strong, easy-to-apply coating is applied to the surface of the reinforcing steel bars to form a rust-preventive coating. The protective coating material provided by this invention, under the synergistic effect of the various raw materials, helps to solidify Cl- and forms a passivation film on the surface of the reinforcing steel bars, further protecting them from corrosion. Furthermore, the coating provided by this invention can form a viscous solution in water, increasing the overall viscosity of the coating or latex, which helps to improve the adhesion of the coating and the adhesiveness of the latex; the coating has good brushing performance and fluidity, and good stability. Implementation data shows that even when a small amount of pitting corrosion occurs on the coated reinforcing steel bars, the remaining uncorroded parts are unaffected, indicating that the coating of this invention has a good bonding effect with the reinforcing steel bars and can effectively delay the corrosion process even when the coating is damaged.

[0048] (4) The steel reinforcement coating of the present invention is a protective coating with strong adhesion and easy to apply, which not only has protective function, but also improves the bonding force between steel reinforcement and concrete, and can also improve the fluidity of the coating during construction. Detailed Implementation

[0049] This invention provides a coating with strong adhesion and easy application, which is made from raw materials comprising the following components: inorganic cementitious materials and modifying additives;

[0050] The inorganic cementitious materials include: C7MS4-C5MS3 phosphoaluminate cement, sulfoaluminate cement, and silicate cement.

[0051] The modified additives include: binders, early strength agents, emulsifying stabilizers, dispersants, and water-reducing agents;

[0052] The adhesive includes: epoxy resin, styrene-butadiene latex, and vinyl acetate-ethylene copolymer powder;

[0053] The early strength agent includes: sodium sulfate, triethanolamine, calcium formate, and urea;

[0054] The emulsifying stabilizers include: phenolic resin and coumarone resin;

[0055] The dispersant includes: sulfonates, fatty alcohol polyoxyethylene ethers, and polyether polyols;

[0056] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0057] In this invention, the inorganic cementitious material contains C7MS4-C5MS3 phosphoaluminate cement, sulfoaluminate cement, and silicate cement in a mass ratio of 50-90:1-10:10-30. The coating made using the coating obtained by the mass ratio can meet the corrosion protection requirements while ensuring the construction performance.

[0058] In this invention, the inorganic cementitious material reacts with the binder. The addition of the emulsifying stabilizer can form a viscous solution in water, increasing the overall viscosity of the coating and helping to improve the adhesion of the coating and the adhesiveness of the latex. The addition of the emulsifying stabilizer also improves the rheological properties of the coating or latex, prevents liquid separation and mutual precipitation, maintains the stability of the emulsion, makes it easier to handle during the coating process, helps to achieve more uniform coating and improve the adhesion of the coating. In addition, it can form a soft film layer during the drying process, increasing the adhesion between the coating and the substrate. The strong adhesion and easy-to-apply coating is a steel reinforcement coating material with infinite development potential.

[0059] In this invention, the adhesive is made of epoxy resin, styrene-butadiene latex, vinyl acetate and ethylene copolymer powder.

[0060] In this invention, the modulus of the adhesive is 1.0 to 10.

[0061] In this invention, the mass ratio of epoxy resin, styrene-butadiene latex, vinyl acetate and ethylene copolymer powder is 10-20:70-80:1-10.

[0062] In this invention, the dosage of the emulsifying stabilizer is preferably adjusted according to different coating methods, including dip coating, brush coating, or spray coating. When the coating method is dip coating or brush coating, the requirements for the fluidity and viscosity of the coating slurry are relatively low, and the mass ratio of the emulsifying stabilizer to the inorganic cementitious material is preferably 0.01 to 0.1:1. When the coating method is spray coating, the requirements for the fluidity and viscosity of the coating slurry are relatively high, and the amount of emulsifying stabilizer added can be appropriately increased to meet the construction requirements of spray coating.

[0063] In this invention, the water-reducing agent is preferably a commonly used concrete water-reducing agent, and more preferably a polycarboxylate water-reducing agent. The selected water-reducing agent can adjust the fluidity of the coating and improve the plastic viscosity of the paste, making it easier to apply.

[0064] This invention also provides a method for preparing the strong adhesion and easy-to-apply steel reinforcement coating described in the above technical solution, comprising the following steps:

[0065] Inorganic cementitious material is obtained by weighing and mixing C7MS4-C5MS3 phosphoaluminate cement, sulfoaluminate cement, and silicate cement in a certain proportion;

[0066] The present invention does not have special requirements for the mixing method and time, as long as a uniformly dispersed mixed powder is obtained.

[0067] The water-reducing agent and deionized water are mixed, and then mixed with binder, early strength agent, emulsifying stabilizer and dispersant to obtain the strong adhesion and easy-to-apply steel reinforcement coating.

[0068] In this invention, the preferred mixing method for the mixed powder and the modified additive is low-speed stirring with a revolution speed of 45-65 r / min, followed by high-speed stirring with a rotation speed of 120-140 r / min, so that the slurry is mixed evenly.

[0069] In this invention, the maintenance preferably includes standard environmental maintenance, the parameters of which include: a maintenance temperature preferably of 25±0.5℃, a relative humidity preferably of 95±5%, and a maintenance time preferably of 28±2 days.

[0070] Example 1

[0071] (1) Weigh 75 parts of C7MS4-C5MS3 phosphoaluminate cement, 5 parts of sulfoaluminate cement and 20 parts of silicate cement, and mix them evenly to obtain inorganic cementitious material;

[0072] The composition of C7MS4-C5MS3 phosphoaluminate cement is as follows:

[0073] Calcium aluminophosphophosphate C8A6P: 28%;

[0074] Calcium aluminate phosphate (C(A,P): 18%)

[0075] Ca5(PO4)2SiO4: 24%;

[0076] α-type Ca3(PO4)2: 6%;

[0077] C4AF: 4%;

[0078] C7MS4-C5MS3: 20%

[0079] (2) Weigh out 90 parts of inorganic cementitious material, 20 parts of binder (the mass ratio of epoxy resin, styrene-butadiene latex, vinyl acetate and ethylene copolymer powder is 10: 80: 5), 10 parts of triethanolamine early strength agent, 0.3 parts of polycarboxylate superplasticizer, 10 parts of fatty alcohol polyoxyethylene ether dispersant, 5 parts of phenolic resin emulsifying stabilizer, and a water-to-binder ratio of 0.3;

[0080] (3) The C7MS4-C5MS3 phosphoaluminate cement, sulfoaluminate cement and silicate cement are first wet-mixed in a polytetrafluoroethylene tank, and then dried in an oven at 80°C. After drying, they are crushed and sieved.

[0081] (4) Add the water-reducing agent to the deionized water weighed in step 1), mix, and let stand;

[0082] (5) Place the binder, emulsifying stabilizer, early strength agent, and dispersant into a mixer, add them to the liquid obtained in step 3), and stir at low speed for 3 minutes at a speed of 45±3 r / min. Then add the inorganic cementitious material mixture powder prepared in step 2), stir at low speed for 2 minutes, let it stand for 90 seconds, and then stir at high speed for 2 minutes at a speed of 120±10 r / min and a speed of 280±10 r / min to obtain an easy-to-apply adhesive steel reinforcement coating.

[0083] Example 2

[0084] The material composition is as follows: 90 parts of inorganic cementitious material (composition is the same as in Example 1), 15 parts of binder (mass ratio of epoxy resin, styrene-butadiene latex, vinyl acetate and ethylene copolymer powder is 10:70:10), 8 parts of triethanolamine early strength agent, 0.3 parts of polycarboxylate superplasticizer, 10 parts of fatty alcohol polyoxyethylene ether dispersant, 5 parts of phenolic resin emulsifying stabilizer, and water-binder ratio of 0.3.

[0085] The preparation method is the same as in Example 1.

[0086] Example 3

[0087] The material composition is as follows: 90 parts of inorganic cementitious material (composition is the same as in Example 1), 20 parts of styrene-butadiene latex adhesive, 10 parts of triethanolamine early strength agent, 0.3 parts of polycarboxylate superplasticizer, 10 parts of fatty alcohol polyoxyethylene ether dispersant, 5 parts of phenolic resin emulsifying stabilizer, and a water-to-binder ratio of 0.3.

[0088] The preparation method is the same as in Example 1.

[0089] Example 4

[0090] (1) Weigh 65 parts of C7MS4--C5MS3 phosphoaluminate cement (composition same as in Example 1), 5 parts of sulfoaluminate cement, and 30 parts of silicate cement, and mix them evenly to obtain inorganic cementitious material.

[0091] (2) Weigh out 90 parts of inorganic cementitious material, 20 parts of binder (composition same as in Example 1), 10 parts of triethanolamine early strength agent, 0.3 parts of polycarboxylate superplasticizer, 10 parts of fatty alcohol polyoxyethylene ether dispersant, 5 parts of phenolic resin emulsifying stabilizer, and water-binder ratio of 0.3;

[0092] Everything else is the same as in Example 1.

[0093] Example 5

[0094] (1) Weigh 70 parts of C7MS4-C5MS3 phosphoaluminate cement, 10 parts of sulfoaluminate cement and 20 parts of silicate cement, and mix them evenly to obtain inorganic cementitious material;

[0095] (2) Weigh out 90 parts of inorganic cementitious material, 20 parts of binder (composition same as in Example 1), 10 parts of triethanolamine early strength agent, 0.3 parts of polycarboxylate superplasticizer, 10 parts of fatty alcohol polyoxyethylene ether dispersant, 5 parts of phenolic resin emulsifying stabilizer, and water-binder ratio of 0.3;

[0096] Everything else is the same as in Example 1.

[0097] Comparative Example 1

[0098] (1) Weigh 75 parts of ordinary phosphoaluminate cement without C7MS4-C5MS3, 5 parts of sulfoaluminate cement and 20 parts of silicate cement, and mix them evenly to obtain inorganic cementitious material;

[0099] (2) Weigh out 90 parts of inorganic cementitious material, 20 parts of styrene-butadiene latex adhesive, 10 parts of triethanolamine early strength agent, 0.3 parts of polycarboxylate superplasticizer, 10 parts of fatty alcohol polyoxyethylene ether dispersant, 5 parts of phenolic resin emulsifying stabilizer, and water-to-binder ratio of 0.3.

[0100] The other steps are the same as in Example 1, to obtain a protective coating material for steel reinforcement without C7MS4-C5MS3 phosphoaluminate cement.

[0101] Application Example 1

[0102] Both coatings prepared in Example 1 and Comparative Example 1 were placed in a carbonization test chamber after molding, and carbonization depth tests were conducted after 90 days and 180 days. The comparative experimental results of the two coatings are as follows:

[0103] Table 1

[0104]

[0105] Application Example 2

[0106] The experiment used 12mm hot-rolled ribbed steel bars commonly used in construction, model HRB400. First, the steel bars were treated to remove rust and oxide layer, and then weighed.

[0107] The coatings prepared according to Examples 1-3 were applied to the surface of the reinforcing bars using a brushing method. After hardening, the coatings were wrapped in plastic wrap and cured in a standard curing room for 3 days, 7 days, and 28 days, respectively. The resulting reinforcing bar coatings from Examples 1-3 were obtained after the curing period. Electrochemical corrosion tests were performed on the reinforcing bar coatings, and the Cl- content was calculated. - Curing rate, the specific results are shown in Table 2.

[0108] Table 2. Curing Cl at different ages of the sample from the examples - performance

[0109]

[0110] Application Example 3

[0111] The experiment used 12mm hot-rolled ribbed steel bars commonly used in construction, model HRB400. First, the steel bars were treated to remove rust and oxide layer, and then weighed.

[0112] The coatings prepared according to Examples 1 and 4-5 were applied to the surface of the reinforcing bars using a brushing method. After hardening, the coatings were wrapped in plastic wrap and cured in a standard curing room for 3 days, 7 days, and 28 days, respectively. The resulting reinforcing bar coatings from Examples 1 and 4-5 were obtained after the curing period. The bond strength of the reinforcing bar coatings was tested, and the specific results are shown in Table 3.

[0113] Table 3. Adhesion strength of different coating base materials for the sample examples

[0114]

Claims

1. A protective coating material for cement-based reinforcing bars containing C7MS4-C5MS3 phosphoaluminate, characterized in that, The components include the following parts by weight: Inorganic cementitious materials: 50-90 parts; Adhesive: 8-20 parts; Emulsion stabilizer: 1-10 parts; Early strength agent: 2-10 parts; Dispersant: 1-10 parts; Water-reducing agent: 0.1-1 part; Water-to-binder ratio: 0.23–0.38; The inorganic cementitious material is composed of the following components in parts by weight: Phosphoaluminate cement containing C7MS4-C5MS3 mineral phase: 65-85 parts; Sulfoaluminate cement: 5-10 parts; Silicate cement: 20-30 parts; The C7MS4-C5MS3 mineral phase phosphoaluminate cement is composed of the following components: Fluoroapatite: 15-20 parts Low-grade bauxite: 30-50 parts; Low-grade limestone: 30-60 parts; Iron powder: 1-10 parts; The modulus of the adhesive is 1.0 to 10; the adhesive is composed of one or more of epoxy resin, styrene-butadiene latex, vinyl acetate and ethylene copolymer powder; the emulsifying stabilizer is composed of one or two of phenolic resin and coumarone resin.

2. The protective coating material for C7MS4-C5MS3 phosphoaluminate cement-based steel reinforcement according to claim 1, characterized in that, The phosphoaluminate cement containing the C7MS4-C5MS3 mineral phase comprises the following system and components: Calcium aluminophosphate C8A6P: 20-30%; Calcium aluminate phosphate (C(A,P):) 15-20%; Ca5(PO4)2SiO4: 20-25%; α-type Ca3(PO4)2: 1-10%; C4AF: 1-10%; C7MS4-C5MS3: 10-20%.

3. The protective coating material for cement-based reinforcing bars containing C7MS4-C5MS3 phosphoaluminate according to claim 1, characterized in that, The adhesive comprises epoxy resin, styrene-butadiene latex, vinyl acetate and ethylene copolymer powder in a mass ratio of 10-20:70-80:1-10.

4. The protective coating material for cement-based reinforcing bars containing C7MS4-C5MS3 phosphoaluminate according to claim 1, characterized in that, The dispersant is composed of one or more of sulfonates, fatty alcohol polyoxyethylene ethers, and polyether polyols.

5. The protective coating material for cement-based reinforcing bars containing C7MS4-C5MS3 phosphoaluminate according to claim 1, characterized in that, The early strength agent is composed of one or more of sodium sulfate, triethanolamine, calcium formate, and urea.

6. A method for preparing a protective coating material for cement-based reinforcing bars containing C7MS4-C5MS3 phosphoaluminate as described in any one of claims 1-5, characterized in that, Includes the following steps: 1) Weigh the fluorinated apatite, low-grade bauxite, low-grade limestone, and iron powder, and calcine them at 1300-1500℃, then rapidly cool, crush, and sieve them to obtain phosphoaluminate cement containing C7MS4-C5MS3 mineral phases. 2) Mix the water-reducing agent, dispersant, binder, early-strength agent, emulsifying stabilizer, and water to obtain a mixed liquid; 3) Then dry-mix the inorganic cementitious materials; 4) Finally, thoroughly stir the well-mixed inorganic cementitious material with the mixed liquid.

7. The application of a C7MS4-C5MS3 phosphoaluminate cement-based steel reinforcement protective coating material as described in any one of claims 1-5 in steel reinforcement rust prevention.

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