CN-121994667-A - Method for researching ion permeation resistance of concrete anti-corrosion coating in extreme corrosion environment

CN121994667ACN 121994667 ACN121994667 ACN 121994667ACN-121994667-A

Abstract

The invention discloses a research method for resisting ion penetration of an extremely corrosive environment to a concrete anti-corrosive coating, which comprises the following steps of S1, coating anti-corrosive coating on the surface of a concrete test piece in a layered manner, S2, carrying out a coating ultraviolet aging test, S3, preparing a mixed solution of NaCl, na 2 SO 4 and nitric acid as corrosive liquid, S4, immersing the concrete test piece subjected to ultraviolet aging in a salt spray test box corrosive liquid, simulating a still water immersion corrosion test environment, S5, testing the concentration of chloride ions, S6, testing the concentration of sulfate ions, S7, carrying out appearance inspection, and evaluating the failure form of the anti-corrosive coating, and S8, wherein the surface anti-corrosive coating corrosion mechanism is disclosed.

Inventors

LI LIANQIANG
SU LE
XU BO
GUO TING
ZHANG LIWEN
WANG HAILIANG
LANG RUIQING
MENG QINGLING
CHENG XINGLEI

Assignees

天津市政工程设计研究总院有限公司
天津市滨海新区城投建设发展有限公司
天津城建大学

Dates

Publication Date: 20260508
Application Date: 20241024
Priority Date: 20240820

Claims (8)

1. The method for researching the ion permeation resistance of the concrete anti-corrosion coating in the extreme corrosion environment is characterized by comprising the following steps: The method comprises the steps of S1, stirring a concrete test piece according to a C45 concrete mixing ratio for 5min, forming a mortar test piece with the thickness of 100mm multiplied by 100mm, vibrating for 15S in a vibrating table, demolding, treating the test piece after demolding, removing floating paste on the mortar test piece by using a steel wire brush, transferring the test piece into a standard curing chamber, taking out the test piece after 28d, standing for 7d at room temperature, polishing a coating surface by using sand paper, slightly cleaning the coating surface by using acetone, cleaning the test piece surface by using clear water, drying at 70 ℃ in an oven for 24h, and layering and smearing anti-corrosion paint on the concrete test piece surface; s2, placing the coated concrete test piece in an ultraviolet-chloride corrosion-sulfate corrosion-high and low temperature comprehensive environment test box, and carrying out a coating ultraviolet aging test; S3, preparing a mixed solution of NaCl, na 2 SO 4 and nitric acid as an etching liquid, and preparing three etching solutions with total ion content higher than 22800 mg/kg; S4, placing the concrete test piece subjected to ultraviolet ageing in a salt spray test box corrosive liquid for immersing, simulating a still water immersing corrosion test environment, and simultaneously simulating a dry-wet alternate corrosion test environment through an immersing-drying alternate action test, wherein four corrosion environment types are adopted, the corrosion environment types comprise (1) immersing 25 ℃, (2) taking 0.68W/m < 2 > from the dry-wet 5 ℃ + ultraviolet radiation intensity, (3) taking 0.68W/m < 2 > from the dry-wet 25 ℃ + ultraviolet radiation intensity, and (4) taking 0.68W/m < 2 > from the dry-wet 45 ℃ + ultraviolet radiation intensity; s5, chloridion concentration test, namely taking out a concrete test piece at a corresponding test period node, respectively cutting a cuboid with the thickness of 4mm,8mm,12mm,16mm and 20mm from the depth of the concrete test piece, taking 5 layers in total, sealing the cut surface of the concrete test piece by using epoxy resin, naturally airing, putting into a corrosion test environment for continuous test, drilling holes on the cut cuboid by using an electric drill to obtain powder, sieving the drilled concrete powder of each layer by using a sand and stone sieve with the thickness of 0.075mm, drying in a drying oven, and finally putting into a dryer to obtain 20g of powder for free chloridion concentration titration; s6, sulfate ion concentration test: S7, performing appearance inspection on the coating by adopting an optical microscope, wherein the main contents are fading, chalking, foaming, cracking and peeling, and evaluating the failure mode of the anti-corrosion coating; and S8, revealing the corrosion prevention mechanism of the surface corrosion prevention coating according to the content of chloride ions and sulfate ions in the concrete test piece and the failure form of the corrosion prevention coating.
2. The method for researching ion permeation resistance of a concrete corrosion protection coating in an extreme corrosion environment according to claim 1, wherein in the step S1, concrete samples are prepared by preparing concrete with a C45 mark, manufacturing corresponding templates, setting the sizes of the concrete samples to be 100mm multiplied by 100mm, taking out the molded concrete samples after 28 days of standard curing, cleaning the surfaces of the coated coatings by using a steel wire brush, air-drying in a room for 1 day, coating 1 surface of the rest of the concrete samples by using epoxy resin, coating other 5 sides by using epoxy resin, taking 1 group of the concrete samples as a blank concrete sample control group, coating 1 surface of the rest of the concrete samples by using epoxy resin, firstly performing ultraviolet ageing test to determine the most advantageous corrosion protection coating, firstly selecting two most advantageous corrosion protection coatings from the concrete samples by using the required concrete blocks with the sizes of 100mm multiplied by 24 mm, secondly coating the two most advantageous corrosion protection coatings from the concrete by using 72 blocks, and subsequently performing the most advantageous corrosion protection coating from the concrete samples by using the three types of 3 (3 types of corrosion protection coatings by 3d and 3d (three types of corrosion protection coatings by 3d and three types of corrosion protection test environments) and 3 = 2 d).
3. The method for researching ion permeation resistance of the concrete anti-corrosion coating in the extreme corrosion environment according to claim 1, wherein in the step S1, four anti-corrosion coatings are selected, wherein the four anti-corrosion coatings comprise two surface coatings, one permeation type and one spraying type; (1) The surface coating is prepared by selecting acrylic acid and chlorinated rubber paint as top paint, and selecting two organic coating systems by considering three organic coating systems of primer, intermediate paint and top paint; (2) The permeability is that the silane material is selected to be coated on the surface of the concrete, so that the silane material can quickly permeate into the concrete to generate chemical reaction with hydrate in the concrete gap, and a silicone macromolecule hydroxyl group with a reticular cross-linked structure is generated; (3) Spray-coating, namely selecting polyurea as a novel solvent-free thick film coating, wherein the thickness of the polyurea coating reaches 1.5mm to 2mm.
4. The method for researching ion permeation resistance of the concrete anti-corrosion coating in the extreme corrosion environment according to claim 1, wherein in the step S2, the concrete test piece after coating is placed in an ultraviolet aging test box, the ultraviolet aging test of the coating is carried out, the test time is 3 d,9 d and 15 d, the coating surface of the concrete test piece faces towards an ultraviolet lamp, the test piece is irradiated by a 500W straight tube-shaped ultraviolet high-pressure mercury lamp, the distance from the ultraviolet lamp to the coated surface is 10 cm, the test temperature is 5 ℃ and 25 ℃ and 45 ℃, the irradiation time is 3 d, 6d, 9 d and 12 d respectively, the water absorption rate of the concrete test piece before and after aging is tested, and the relationship between the ultraviolet aging time and the coating can be obtained by testing the water absorption rate.
5. The method for researching ion permeation resistance of a concrete anti-corrosive coating in an extreme corrosion environment according to claim 1, wherein in the step S3, the first corrosion solution comprises 3000mg/L nitric acid, 10000mg/L sodium sulfate, 10000mg/L sodium chloride, the second corrosion solution comprises 3000mg/L nitric acid, 15000mg/L sodium sulfate, 5000mg/L sodium chloride, and the third corrosion solution comprises 3000mg/L nitric acid, 5000mg/L sodium sulfate, 15000mg/L sodium chloride.
6. The method for researching the ion permeation resistance of the concrete anti-corrosion coating in the extreme corrosion environment according to claim 1, wherein in the step S4, parameters simulating the dry-wet alternate corrosion test environment are 30 days, 60 days and 90 days, and the alternate time in the dry-wet alternate test is 3 days, wherein a concrete test piece is soaked, put in a solution, drain out the solution for 16 hours, the drying temperature of the concrete test piece is 85 ℃ for 6 hours, and the cooling time is 2 hours.
7. The method for researching ion permeation resistance of the concrete anti-corrosion coating in the extreme corrosion environment according to claim 1, wherein in the step S5, the method for titrating the concentration of free chloride ions is as follows: Weighing 20.00g of ground mortar powder to 0.1g, placing in a triangular flask, adding 100mL of distilled water, shaking uniformly, covering a surface dish, placing on a test electric furnace or other heating devices with asbestos meshes, boiling for 5min, stopping heating, covering a bottle stopper, standing for 24h, and filtering with rapid quantitative filter paper to obtain filtrate; SS2, respectively transferring 20mL of two filtrate, placing the filtrate into two triangular flasks, respectively adding two drops of phenolphthalein indicator, and neutralizing with nitric acid solution until the filtrate is just colorless; And SS3, respectively adding 10 drops of acid indicator into the two filtrates before titration, then dripping the silver nitrate standard solution until the yellow with a slight pink color does not disappear, keeping consistent color judgment of the end point, respectively recording the volumes V 1 and V 2 of the respectively consumed silver nitrate standard solution, and taking the average value V of the volumes as a measurement result.
8. The method for researching ion permeation resistance of the concrete anti-corrosion coating in the extreme corrosion environment according to claim 1, wherein in the step S6, the sulfate ion concentration test method is that sampling is carried out from different depths of a concrete test piece, 4mm is taken from the position of 4mm,8mm is taken from the position of 12mm is taken from the position of 16mm is taken from the position of 20mm, the thickness of each slice is taken to be 4mm, each slice is naturally dried and then put into a self-sealing bag, a label is attached for standby, finally, the dried slices of different layers are repeatedly ground by using an agate mortar, concrete powder samples with the same depth are uniformly mixed, the sulfate ion content is measured according to a modified barium sulfate weight method by taking 0.5g of powder each time, and the process is repeated for 6 times, and the average value of the sulfate ion content of the layer is taken as the sulfate ion content of the layer.

Description

Method for researching ion permeation resistance of concrete anti-corrosion coating in extreme corrosion environment Technical Field The invention relates to the technical field of building materials, in particular to a method for researching ion permeation resistance of a concrete anti-corrosion coating in an extreme corrosion environment. Background At present, the technical means of coating the surface with an anti-corrosion coating is generally adopted as anti-corrosion measures of reinforced concrete structures at home and abroad, the method has the advantages of simple principle, convenient operation on construction sites, no influence on construction period, mature technology, wide application, high cost performance, longer anti-corrosion period and 30 years of common anti-corrosion coating. Under the condition of not changing the mixing ratio of concrete materials, the method is used for the anticorrosion measures of special areas such as the seawater splashing area, the dry-wet alternation and the like of the reinforced concrete bridge. The construction process and the material selection of the anti-corrosion coating can influence the durability index of the reinforced concrete structure, and the performance of the anti-corrosion coating can be obviously reduced under the repeated action of ultraviolet light and fatigue stress load along with the increase of the service time of the structure, so that each factor influencing the bonding performance of the coating needs to be deeply explored, and the anti-corrosion coating is optimized according to the factors, so that the anti-corrosion coating can be better adapted to the climatic environment of a structural engineering area. Chloride ions can invade concrete through a variety of mechanisms such as diffusion, osmosis, capillary action, etc., with diffusion being generally considered the dominant means of invasion. In 1970, european scholars Collepardi proposed a theoretical model of chloride ion diffusion in concrete based on Fick's second law, but many research results at present indicate that the chloride ion diffusion process is comprehensively influenced by factors such as external environment, load type and size, concrete material characteristics and internal moisture content. In order to obtain the chloride ion permeation law under the influence of various factors, various scholars perform relevant correction on chloride ion diffusion coefficients, guo Dongmei and the like aiming at in-service concrete bridges in coastal areas, on the basis of summarizing existing diffusion models, a chloride ion diffusion correction model considering service time, chloride ion combination effect and vehicle load effect is established, relevant data in engineering examples are accurately predicted based on the correction model, populus and the like aiming at natural conditions of the in-service concrete bridges in southeast China are provided, an off-shore air area improvement chloride ion diffusion model considering service time, temperature, relative humidity, load effect and chloride ion combination capacity is provided, the influence of coupling effect of service time and internal stress on the chloride ion diffusion coefficients is studied by Wang and the like by using test data in literature, a relevant correction model is established, finally a chloride concentration prediction method is verified by using two groups of test data, the influence of water gel ratio, cement component and hydration degree on the chloride ion effective diffusion coefficients is studied, and a multi-chloride ion diffusion model is established, and a test result with a confidence coefficient of 95% is obtained. In addition, sulfate attack is also an important environmental factor affecting the durability of concrete structures, sulfate ions in the external environment react with cement hydration products to form gypsum or ettringite, which is an acicular swelling product that, as its volume increases, can generate internal stress at the contact point with the pore walls. Microcracks appear inside the concrete when the expansion stress exceeds the tensile strength of the concrete, and the appearance and extension of microcracks also accelerate the penetration rate of sulfate ions in the concrete. Many scholars research the mechanism and transmission process of sulfate erosion, wherein a modified sulfate ion diffusion model proposed by Marchand et al is widely applied, the model considers the ion diffusion effect, the electron coupling effect and the chemical activity gradient effect, analyzes the influence of the chemical reaction process on the erosion result, and Xu Hui researches the influence of the water-gel ratio, the solution concentration and the curing time on the sulfate ion diffusion performance, and the result shows that the diffusion coefficient increases with the increase of the water-gel ratio and the solution concentration and decreases with the extension of the