阅读说明：本技术 一种提升混凝土抗微生物腐蚀性能的方法 (Method for improving antimicrobial corrosion performance of concrete ) 是由 朱正宇 储洪强 宋子健 郭明志 蒋林华 李怡 张宇衡 于丽波 于 2020-03-18 设计创作，主要内容包括：本发明公开了一种提升混凝土抗微生物腐蚀性能的方法,将内置钢筋的混凝土浸没于直流电解装置的乳酸铜电解液中,以混凝土中的钢筋为阴极,进行直流电解；再清洗电解后的混凝土、吹干,依次浸泡于多巴胺溶液、正十二硫醇溶液中镀膜,取出后清洗、吹干。其通过在混凝土表面沉积铜及铜氧化物提升混凝土的抗微生物腐蚀性能；通过在沉积物表面添加的复合镀层,提高试件表面的疏水性,减少铜离子浸出,提高沉积物的使用寿命；通过采用硝酸铜替换了硫酸铜制备的电解液,避免电沉积过程中硫酸根离子对混凝土性能的影响。本发明提供的混凝土电沉积方法及装置结构简单、操作简捷、防腐效果好,具有很强的实用性和广泛的适用性。(The invention discloses a method for improving the antimicrobial corrosion performance of concrete, which comprises the steps of immersing concrete with built-in reinforcing steel bars in a copper lactate electrolyte of a direct current electrolysis device, and performing direct current electrolysis by taking the reinforcing steel bars in the concrete as cathodes; and cleaning the electrolyzed concrete, blow-drying, sequentially soaking the electrolyzed concrete in a dopamine solution and a n-dodecyl mercaptan solution for film plating, taking out the electrolyzed concrete, cleaning and blow-drying. The antimicrobial corrosion resistance of the concrete is improved by depositing copper and copper oxide on the surface of the concrete; the composite plating layer added on the surface of the deposit improves the hydrophobicity of the surface of the test piece, reduces the leaching of copper ions and prolongs the service life of the deposit; the electrolyte prepared from copper sulfate is replaced by copper nitrate, so that the influence of sulfate ions on the performance of the concrete in the electrodeposition process is avoided. The concrete electrodeposition method and the device provided by the invention have the advantages of simple structure, simple operation, good anticorrosion effect, strong practicability and wide applicability.)

1. A method of enhancing the antimicrobial corrosion performance of concrete comprising the steps of:

s1, immersing the concrete with built-in steel bars in the copper lactate electrolyte of the direct current electrolysis device, and performing direct current electrolysis by taking the steel bars in the concrete as cathodes;

s2, cleaning the electrolyzed concrete, drying by blowing, soaking the electrolyzed concrete in a dopamine solution for film plating, taking out the electrolyzed concrete, cleaning and drying by blowing;

and S3, soaking the film in n-dodecyl mercaptan solution for film plating, taking out the film, cleaning and drying the film.

2. The method for improving the antimicrobial corrosion performance of concrete according to claim 1, wherein the cathode of the direct current electrolysis device is a concrete built-in steel bar soaked in electrolyte, the anode is a titanium mesh, the electrolyte is a copper lactate solution, and a direct current power supply supplies power to the cathode and the anode;

the anode is connected with a voltmeter in series, and the cathode is connected with an adjustable resistor in series.

3. The method for improving the antimicrobial corrosion performance of concrete according to claim 1, wherein the cleaning is performed by using deionized water, and the blow-drying is performed by using inert gas.

4. The method for improving the antimicrobial corrosion performance of concrete according to claim 1, wherein the concentration of the dopamine solution is 0.02 mol/L, the soaking time is 8-10 hours, and the solution temperature is 25 ℃.

5. The method for improving the antimicrobial corrosion performance of concrete according to claim 1, wherein the n-dodecyl mercaptan concentration is 0.1 mol/L, the soaking time is 12-14 hours, and the solution temperature is 50 ℃.

6. The method for improving the antimicrobial corrosion performance of concrete according to claim 1, wherein the distance between the anode and the concrete is 20mm-40mm, and the distance between the cathode and the anode is 30mm-50 mm;

the output voltage of the DC power supply is 20V-50V, and the current density applied to the cathode is 0.5-5A/m²The electrifying time is 5-20 days, and the replacement period of the electrolyte is 5 days per time.

7. The method for improving the antimicrobial corrosion performance of concrete according to claim 6, wherein the current density is 1.5-2.5A/m²And the electrifying time is 15 days.

8. The method for improving the antimicrobial corrosion performance of concrete according to claim 1, wherein the copper ion concentration of the copper lactate solution in the electrolyte is 0.2-0.6 mol/L.

9. The method for improving the antimicrobial corrosion performance of concrete according to claim 1, wherein the electrolyte is prepared by the following steps:

s1, mixing the lactic acid solution and the copper nitrate solution according to the molar mass ratio, and stirring;

s2, adjusting the pH of the mixed solution to be alkaline by using a sodium hydroxide solution, and standing;

and S3, heating to a certain temperature, maintaining the temperature and standing to prepare the electrolyte.

10. The method for improving the antimicrobial corrosion performance of concrete according to claim 9, wherein the concentration of the lactic acid solution in the step S1 is 3 mol/L, the concentration of the copper nitrate solution is 0.6 mol/L, and the molar mass ratio of the lactic acid solution to the copper nitrate solution is 1: 5;

in the step S2, the concentration of the sodium hydroxide solution is 5 mol/L, and the adjusted pH is 8-9;

the temperature maintained in step S3 is 60-80 deg.C, and the standing time is 12 h.

Technical Field

The invention belongs to the field of durability of concrete structures, and particularly relates to a method for improving the antimicrobial corrosion performance of concrete.

Background

Microbial corrosion is one of the major causes of damaged concrete sewer pipes. Sewage and sludge layers accumulated at the bottom of the pipeline contain a large amount of bacteria, wherein sulfate reducing bacteria and sulfate oxidizing bacteria have serious harm to concrete. Sulfuric acid generated by the metabolism of the calcium sulfate and the calcium sulfate chemically reacts with cement hydration to generate expansive ettringite and gypsum on one hand, so that microcracks are generated in concrete; on the other hand, the reaction consumes a large amount of Ca (OH)₂The pH value of the concrete is reduced, and the steel bar passive film is damaged. The microbial attack of concrete not only causes great economic losses but also severely damages the structural safety of the sewer line. A great deal of research is carried out by a plurality of scholars on the corrosion process and mechanism of the microorganism to the concrete, and a series of measures are taken on the basis of the research to protect the microorganism corrosion of the concrete.

The coating technology can play an effective antibacterial and anticorrosive effect at the initial stage, but because the bonding property of the coating material and the concrete surface is poor, under the scouring action of sewage flow, the surface coating can be peeled off and fall off, and the later-stage anticorrosive effect is very poor. In addition, for the existing pipelines which are corroded, the coating method is difficult to implement and high in cost, and the corroded concrete surface has poorer bonding performance with the coating material and is difficult to play a role in long-term corrosion prevention.

In order to enhance the binding force between the protective layer and the concrete matrix, cuprous oxide is deposited on the inner side of the pipeline by using an electrochemical deposition method. The preparation of the cuprous oxide by the electrodeposition method is convenient and quick, the cost is low, and the cuprous oxide can form stronger binding force with the surface of the concrete under the action of an electric field. Because the electro-deposition of cuprous oxide on a concrete matrix is a novel technology, the method mainly has the following defects at present:

1. in the previous research, the selection of electrodeposition parameters mainly refers to the parameters of metal electrodeposition, the concrete matrix and the metal matrix have great difference, the concrete has great resistance and complex surface structure, and the electrodeposition parameters suitable for the concrete matrix need to be selected;

2. previous researches mainly focus on improving the purity of cuprous oxide, so that the copper content deposited on the surface of concrete is very low, but the cuprous oxide is easily oxidized into CuO in an actual sewage pipeline, and the Cu and the CuO also have good bactericidal performance, so that the improvement of the content of copper elements on the surface of the concrete is the key of the antimicrobial performance;

3. usually, the electrolyte used for electrodepositing the cuprous oxide is a mixed solution of copper sulfate and lactic acid, but a concrete sample is soaked in a solution containing sulfate radicals for a long time and can react to generate ettringite and gypsum to influence the performance of the concrete, so that the solution composition of the electrolyte needs to be changed;

4. under the washing of sewage, the cuprous oxide and the cupric oxide of deposit on concrete surface leach easily, lead to the life of cladding material lower, consequently need do the subsequent processing after the redeposition, promote its durability.

Disclosure of Invention

The invention aims to make up the defects of the prior art, and provides a method and a device for improving the antimicrobial corrosion performance of concrete, so as to improve the content of copper in a coating.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

a method of enhancing the antimicrobial corrosion performance of concrete comprising the steps of:

s1, immersing the concrete with built-in steel bars in the copper lactate electrolyte of the direct current electrolysis device, and performing direct current electrolysis by taking the steel bars in the concrete as cathodes;

s2, cleaning the electrolyzed concrete, drying by blowing, soaking the electrolyzed concrete in a dopamine solution for film plating, taking out the electrolyzed concrete, cleaning and drying by blowing;

and S3, soaking the film in n-dodecyl mercaptan solution for film plating, taking out the film, cleaning and drying the film.

The cathode of the direct current electrolysis device is a concrete built-in steel bar soaked in electrolyte, the anode is a titanium mesh, the electrolyte is a copper lactate solution, and a direct current power supply supplies power to the cathode and the anode;

the anode is connected with a voltmeter in series, and the cathode is connected with an adjustable resistor in series.

The cleaning adopts deionized water, and the blow-drying adopts inert gas.

The concentration of the dopamine solution is 0.02 mol/L, the soaking time is 8-10 hours, and the solution temperature is 25 ℃.

The concentration of the n-dodecyl mercaptan is 0.1 mol/L, the soaking time is 12-14 hours, and the solution temperature is 50 ℃.

The distance between the anode and the concrete is 20mm-40mm, and the distance between the cathode and the anode is 30mm-50mm in the direct current electrolysis;

the output voltage of the DC power supply is 20-50V, and the current density applied to the cathode is 0.5-5A/m²The electrifying time is 5-20 days, and the replacement period of the electrolyte is 5 days per time.

Further, the current density is 1.5-2.5A/m²And the electrifying time is 15 days.

The copper ion concentration of the electrolyte solution copper lactate solution is 0.2-0.6 mol/L, preferably 0.4-0.6 mol/L.

The preparation of the electrolyte comprises the following steps:

s1, mixing the lactic acid solution and the copper nitrate solution according to the molar mass ratio, and stirring;

s2, adjusting the pH of the mixed solution to be alkaline by using a sodium hydroxide solution, and standing;

and S3, heating to a certain temperature, maintaining the temperature of the electrodeposition solution, and standing to prepare the electrolyte.

In the step S1, the concentration of the lactic acid solution is 3 mol/L, the concentration of the copper nitrate solution is 0.6 mol/L, and the molar mass ratio of the lactic acid solution to the copper nitrate solution is 1: 5;

in the step S2, the concentration of the sodium hydroxide solution is 5 mol/L, and the adjusted pH is 8-9;

the temperature of the electrodeposition solution maintained in step S3 is 60-80 ℃, and the standing time is 12 hours.

The heating manner in step S3 includes water bath heating.

The invention has the advantages that:

compared with the effect of a common coating, the binding power between the electrodeposit and the concrete matrix is obviously improved; besides copper and oxides deposited on the surface, copper ions also enter the concrete under the action of an electric field, so that the impermeability of the concrete is improved. Compared with the existing electrodeposition process, the method has the advantages that the content of copper elements on the surface of the concrete can be effectively improved by prolonging the electrifying time, and meanwhile, the preferable electrifying time of 15 days also avoids local convex nodules from being generated due to overlong electrifying time, so that the integrity of the coating is damaged; cuprous oxide, copper oxide and copper simple substances in the sediments all have good bactericidal performance, can effectively inhibit the growth and reproduction of sulfate reducing bacteria and sulfate oxidizing bacteria, prevent the generation of biological sulfuric acid, and can effectively improve the durability of a concrete structure in a sewage environment. After the electrodeposition process, the dopamine-n-dodecyl mercaptan composite coating is added on the surface of the deposit, so that the hydrophobicity of the surface of the test piece can be improved, the leaching of copper ions is reduced, and the service life of the deposit is prolonged.

In addition, the copper nitrate solution is adopted to replace the traditional copper sulfate solution. Both the copper nitrate solution and the copper oxide can deposit cuprous oxide sediments with better effect, and the influence of sulfate ions on the performance of the concrete in the electrodeposition process can be avoided by selecting the copper nitrate solution. The concrete electrodeposition method and the device provided by the invention have the advantages of simple structure, simple operation, good anticorrosion effect, strong practicability and wide applicability.

Drawings

FIG. 1 is a schematic view of the structure of a direct current electrolyzer of the present invention; wherein the reference numerals are: 1. electrolyte, 2, a direct current power supply, 3, an adjustable resistor, 4, a voltmeter, 5, an anode, 6, a cathode, 7 and a concrete sample.

FIG. 2 is the coverage of the deposit on the surface of the test piece after 15 days of electrodeposition.

FIG. 3 is an SEM-EDS image of the surface of the test piece after 15 days of electrodeposition.

FIG. 4 shows the adhesion of sulfate-oxidizing bacteria (SOB) on the surface of a test piece after 15 days of electrodeposition; wherein, the graph a is the untreated surface of the test piece, and the graph b is the surface of the test piece after electrodeposition.

FIG. 5 is a graph showing the change in pH of the bacterial solution over a 60 day period.

Fig. 6 shows the coverage of the deposit on the surface of the test piece for 5 days, 10 days and 20 days of electrodeposition, respectively.

FIGS. 7 to 9 are SEM-EDS images of the surface of each test piece after 5 days, 10 days and 20 days of electrodeposition.

FIG. 10 is the surface topography of the test pieces after electrodeposition for 15 days in a copper sulfate and lactic acid solution.

FIG. 11 is an XRD pattern of a mortar coupon at a depth of 10mm from the surface of the coupon.

Detailed Description

The invention is described in detail below with reference to the figures and the embodiments.

The instrument and the standard detection method used by the invention comprise the following steps:

XRD X-ray diffraction method, which obtains the crystal image and component composition of the sample by normalizing the position and intensity of the diffraction peak of the sample and comparing with standard PDF card, wherein XRD adopts DMAX/rB X-ray diffractometer from Japan science company, the test conditions are that Cu K α (lambda =1.5406 Å) target, tube current is 30mA, and the scanning range is 2 theta =30^o-60^oAt a scanning speed of 2^o/min。

SEM-EDS: the scanning electron microscope is a microscopic testing means between the transmission electron microscope and the optical microscope, and can directly utilize the physical properties of a sample to carry out microscopic imaging. In the patent, the SEM adopts a JSM-5900 type scanning electron microscope of Japan Electron company, and the test acceleration voltage is 20 kV.

ICP-OES in the patent, the inductively coupled plasma spectrometry adopts a PerkinElmer 8300 type inductively coupled plasma emission spectrometer of PERKINE L MER company, the radio frequency power of plasma is 1.0kW, the flow rate of plasma gas is 15.0L/min, the flow rate of auxiliary gas is 1.5L/min, the pressure of an atomizer is 240kPa, the time for one-time reading is 5s, the instrument stability is delayed for 15s, the sample introduction is delayed for 5s, the pump speed is 15r/min, the reading times are 5 times, and the wavelength of copper element is 327.395 nm.

Sulfate-oxidizing bacteria (SOB) resistance test: the sulfate oxidizing bacteria used in the patent are thermophilic sulfur bacilli and are preserved by China center for industrial microorganism culture, with the culture number CICC 24169; immersing the concrete test piece in the SOB bacteria culture solution, and observing the change of the bacterial number for 15 days, 30 days, 45 days and 60 days; the change of the bacterial quantity is tested by adopting a blood counting plate method and an ultraviolet spectrophotometer.

Preparing a concrete sample: a mortar test piece is adopted, the size is 40mm x 160mm, cement is PII42.5, the water cement ratio is 0.5, the glue sand ratio is 2.5, the cement and sand are firstly stirred for 60s, water is added, then stirring is continuously carried out for 120s, the stirred slurry is filled into 1/2 with the height of a mold (160 x 40 mm), a vibration table is placed for vibration for 30s, then a reinforcing steel bar piece with the thickness of 120 x 30 x 20mm is placed, one end of the reinforcing steel bar piece is connected with a copper wire, the residual mold is filled with the mortar, and vibration is continuously carried out for 30 s. After 24h, the mould was removed and cured in a standard curing chamber (20. + -. 2 ℃ C. and 95% relative humidity) for 28 days.

As shown in FIG. 1, the device for improving the anti-microbial corrosion performance of concrete of the invention comprises an electrolyte 1, a direct current power supply 2, an adjustable resistor 3, a voltmeter 4, an anode 5, a cathode 6, a concrete sample 7 and a lead. And completely soaking a concrete test piece 7 in the electrolyte 1, taking a steel bar in the concrete test piece as a cathode 6, taking a high-purity titanium mesh as an anode 5, placing the anode 5 at a position 20-50mm away from the lower part of the cathode 6, and respectively connecting the anode 5 and the cathode 6 with the positive electrode and the negative electrode of the direct-current power supply 2 through leads. The current density applied by the direct current power supply 2 is 0.5-5A/m²The power-on period (electrodeposition time) is 5 to 20 days.

The electrolyte 1 is a copper lactate solution generated by mixing copper nitrate and lactic acid, wherein the concentration of the copper nitrate is 0.2-0.6 mol/L, the concentration of the lactic acid is 1-3 mol/L, the pH of the mixed solution is adjusted to 8-9 by using a sodium hydroxide solution of 5 mol/L, the solution is fully mixed, then the solution is kept still for 12 hours, the temperature of the electrolyte is maintained at 60-80 ℃ by a water bath heating device, and the electrolyte is replaced once every 5 days to ensure that sufficient copper ions are in the solution.

After the electrodeposition is finished, cleaning the surface of a test piece by deionized water, drying by blowing by argon, immersing the test piece in a dopamine solution with the concentration of 0.02 mol/L, adjusting the temperature to 25 ℃ in a water bath, taking out after immersing for 8 hours, cleaning by deionized water, drying by blowing by argon, immersing in an n-dodecyl mercaptan solution with the concentration of 0.1 mol/L, adjusting the temperature to 50 ℃ in a water bath, immersing for 12 hours, and taking out.