阅读说明：本技术 一种防硫酸盐侵蚀混凝土及配比优化方法与应用 (Sulfate erosion preventing concrete and proportioning optimization method and application ) 是由 许崇帮 李雪峰 王华牢 高晓静 于 2021-10-21 设计创作，主要内容包括：本发明为工程领域的一种防硫酸盐侵蚀混凝土及其应用,具体涉及一种防硫酸盐侵蚀混凝土及试验方法与应用,所述混凝土由基料、骨料、掺合料、外添加剂及水混合搅拌而成,所述混凝土的组分及质量份数如下：所述基料为强度等级42.5的普通硅酸盐水泥17.4-17.5份；所述骨料包括细骨料和粗骨料,所述粗骨料为粒径5-10mm的玄武岩38.9份,所述细骨料为玄武岩质中砂33.1-33.2份；所述掺合料为硅粉或活性指数大于80％的粉煤灰1.9-1.95份,与现有技术相比,本发明的有益效果是：模拟工程实际的配比试验,结合弱透水性石膏岩地层的特殊腐蚀环境,再现硫酸盐型侵蚀的全过程并分析侵蚀成因,为防腐蚀混凝土材料的选取及组成设计的提供理论依据,所述试验中试样的组分及配比均结合工程现状及侵蚀特点设置。(The invention relates to a sulfate erosion preventing concrete and application thereof in the field of engineering, in particular to a sulfate erosion preventing concrete and a test method and application thereof, wherein the concrete is prepared by mixing and stirring base materials, aggregate, admixture, external additive and water, and the concrete comprises the following components in parts by weight: the base material is 17.4 to 17.5 parts of ordinary Portland cement with the strength grade of 42.5; the aggregate comprises fine aggregate and coarse aggregate, wherein the coarse aggregate is 38.9 parts of basalt with the particle size of 5-10mm, and the fine aggregate is 33.1-33.2 parts of basalt medium sand; the admixture is 1.9-1.95 parts of silica powder or fly ash with the activity index of more than 80%, compared with the prior art, the invention has the beneficial effects that: the method is characterized by simulating an actual proportioning test of engineering, combining a special corrosion environment of a weak water permeability gypsum rock stratum, reproducing the whole process of sulfate type corrosion and analyzing corrosion causes, providing a theoretical basis for selection and composition design of an anti-corrosion concrete material, and setting components and proportioning of a sample in the test according to the current situation of the engineering and corrosion characteristics.)

1. The concrete for preventing sulfate erosion is characterized by being prepared by mixing and stirring a base material, an aggregate, an admixture, an external additive and water, wherein the concrete comprises the following components in parts by weight:

the base material is 17.4 to 17.5 parts of ordinary Portland cement with the strength grade of 42.5;

the aggregate comprises fine aggregate and coarse aggregate, wherein the coarse aggregate is 38.9 parts of basalt with the particle size of 5-10mm, and the fine aggregate is 33.1-33.2 parts of basalt medium sand;

the admixture is 1.9 to 1.95 parts of silica powder or fly ash with the activity index of more than 80 percent;

6.9-7 parts of water;

the external additive is a liquid preservative and a water reducing agent, the water reducing agent is 0.23-0.24 part of polycarboxylic acid water reducing agent, and the preservative is 1.34-1.35 parts of sulfate erosion resistant type.

2. The proportioning optimization method of the sulfate erosion preventing concrete is characterized by comprising the following steps:

(1) determining the components and the proportion of a basic sample and a comparison sample according to the erosion characteristic of the sulfate and the parameters of the corrosive environment;

(2) manufacturing test sample assemblies for testing according to different components and proportions, and performing basic maintenance for 28 days, wherein the basic maintenance comprises ordinary maintenance and special maintenance;

(3) considering the influence of external carbonate ions, two samples with the same component and the same proportion are arranged, and the two samples are respectively cured by adopting a standard curing mode and a low-temperature curing mode;

(4) respectively recording maintenance data of the sample in different maintenance durations;

(5) observing the appearance of the sample, and testing the deep components of the sample by an XRD test;

(6) comparing the test results and obtaining the optimal components and proportion of the anti-corrosion concrete according to the test results;

in the step (2), standard maintenance is carried out at room temperature of 20 ℃, and magnesium sulfate solution and 10% limestone powder aqueous solution are adopted for flow infiltration to reach 95% relative humidity;

the low-temperature maintenance in the step (2) is to place the test piece in a solution with the temperature of 4-6 ℃ for immersion maintenance, wherein the solution is a mixed solution of 10% limestone powder aqueous solution and magnesium sulfate solution;

and (2) respectively setting a common sample, an optimized cement sample, an optimized proportioning and optimized cement sample, an internal sulfate ion preparation sample, a carbonate ion invasion sample considered by optimized proportioning and a carbonate ion invasion sample considered by optimized cement according to the corrosion of the C-S-Caulite type sulfate in the step (1).

3. A proportioning optimization method for sulfate attack-resistant concrete according to claim 2, wherein the components of the sample in the step (1) are set as follows:

the composition of the common sample was: P.O cement with the strength of 42.5, water, fly ash, limestone, medium sand, a liquid preservative and a water reducing agent;

on the basis of a common sample, replacing cement in the common sample with P.I cement with the strength of 42.5 by the optimized cement sample;

the components of the optimized proportioning sample are as follows: P.O cement with the strength of 42.5, water, fly ash, basalt, medium sand, a liquid preservative and a water reducing agent;

optimizing the mixture ratio and optimizing the components of the cement sample, and replacing the cement in the sample with P.I cement with the strength of 42.5 on the basis of optimizing the mixture ratio;

the components for preparing the sulfate ion sample inside are as follows: P.O cement with the strength of 42.5, water, limestone powder, limestone, medium sand and a water reducing agent.

4. The proportioning optimization test method for the sulfate attack-preventing concrete according to claim 2, wherein the proportioning of the samples is as follows:

the common samples comprise the following components in parts by weight: 393 parts of P.O cement with the strength of 42.5, 200 parts of water, 48 parts of fly ash, 934 parts of limestone, 796 parts of medium sand, 32.5 parts of a liquid preservative, 3.84 parts of a water reducing agent and the water-cement ratio of 0.45;

optimizing a cement sample, on the basis of a common sample, replacing 393 parts of P.I cement with the strength of 42.5 by cement in the common sample;

the mass parts of the optimized proportioning samples are as follows: P.O cement with the strength of 42.5, 168 parts of water, 47 parts of fly ash, 940 parts of basalt, 801 parts of medium sand, 32.5 parts of liquid preservative, 5.64 parts of water reducing agent and the water-cement ratio of 0.36;

optimizing the mixture ratio and optimizing the cement sample, and replacing 422 parts of P.I cement with the strength of 42.5 in the cement sample with the optimized mixture ratio;

the sulfate ion sample prepared inside comprises the following components in parts by weight: P.O parts of cement with the strength of 42.5, 190 parts of water, 47 parts of limestone powder, 864 parts of limestone, 974 parts of medium sand, 5.64 parts of a water reducing agent and the water-cement ratio of 0.35;

during 28 days of basic maintenance, the samples are subjected to common maintenance by spraying aqueous solution;

the optimized proportion considers that carbonate ions invade the sample as the optimized proportion sample, and limestone powder aqueous solution with the concentration of 10% is adopted for spray maintenance in 28-day basic maintenance, so that the sample is specially maintained;

the optimized cement takes the carbonate ion invasion sample as an optimized proportion, and the cement sample is optimized to be sprayed and maintained by limestone powder aqueous solution with the concentration of 10% in 28-day basic maintenance, which is special maintenance.

5. The proportioning optimization method for sulfate attack-preventing concrete according to claim 2, wherein: the curing time in the step (3) is 1 month, 3 months, 6 months, 9 months and 12 months respectively.

6. A method of designing a tunnel lining using the sulfate attack preventing concrete according to claim 1, characterized in that: the tunnel lining is designed in a full-ring closed mode, surrounding rocks at the periphery of the lining are blocked by grouting, the anti-corrosion concrete impermeability grade of the primary lining of the tunnel is greater than P6, the anti-corrosion concrete impermeability grade of the secondary lining is greater than P8, and the corrosion resistance coefficient of the anti-corrosion concrete in the lining is greater than 0.8.

Technical Field

The invention relates to a sulfate erosion preventing concrete and application thereof in the field of engineering, in particular to a sulfate erosion preventing concrete and a proportioning optimization method and application thereof.

Background

The existing research shows that under the condition of sulfate, water and a certain temperature, the carbon-sulfur-calcium-silica-type sulfate erodes cement-based concrete (TSA) containing limestone powder or limestone admixture to destroy the gel property, the patent number is 201110192758.6, the background technology of the inhibitor for the corrosion of the carbon-sulfur-calcium-silica-type sulfate and the preparation method thereof also indicates that aiming at the corrosion of the carbon-sulfur-calcium-silica-type sulfate, the common anti-corrosion concrete can not achieve the anti-corrosion effect, and the special anti-corrosion concrete can play the anti-corrosion role, but the ingredients and the process are complex, the manufacture is complicated, the transportation cost is high, and the inhibitor is not suitable for the actual engineering.

The principle of the inhibitor is that a wrapping layer is formed on the surface of concrete to inhibit corrosion reaction, but the inhibitor is poor in application in tunnel engineering under special working conditions, mainly the tunnel concrete surface layer, especially primary support, is not a flat surface, and is difficult to generate an effective wrapping layer.

In practical engineering, the concrete of the tunnel lining is corroded more complexly, namely, the external corrosion condition formed by surrounding rock mass and underground water and the water seepage and corrosion in the concrete, for example, in Taihang mountain areas in North China, the attack of the C-S-Si-Ca-stone type sulfate exists, but the area is a gypsum rock stratum with weak water permeability, the water seepage amount and the corrosion conditions are different from the common attack of the calcium carbo-sulfur-calcium-stone type sulfate, most of the existing tests for the attack of the sulfocarbonite-type sulfate are directed at tests of the formation mechanism and related parameters of the sulfocarbonite, are mostly used for indoor theoretical research and analysis, lack scientific and effective proportioning research for corrosion of actual engineering environment, and need related proportioning tests and researches on components and contents in the tests in basic research applied to engineering practice, therefore, the basic test needs to be combined with the proportioning optimization test to achieve the technical effect in practical application.

Therefore, the development of the sulfate erosion preventing concrete and the proportioning optimization method and application have urgent research values, and also have good economic benefits and industrial application potentials, which are the basis and the place of the power to be completed by the invention.

Disclosure of Invention

The present inventors have conducted intensive studies to overcome the above-identified drawbacks of the prior art, and as a result, have completed the present invention after having made a great deal of creative efforts.

Specifically, the invention provides a concrete for resisting attack of a C-S-Caulite type sulfate, a proportioning optimization method and application, and discloses theoretical and experimental basis of the anti-corrosion concrete in engineering practical application.

In order to achieve the purpose, the invention provides the following technical scheme:

the concrete for preventing sulfate erosion is prepared by mixing and stirring a base material, an aggregate, an admixture, an external additive and water, and comprises the following components in parts by weight:

the base material is 17.4 to 17.5 parts of ordinary Portland cement with the strength grade of 42.5;

the aggregate comprises fine aggregate and coarse aggregate, wherein the coarse aggregate is 38.9 parts of basalt with the particle size of 5-10mm, and the fine aggregate is 33.1-33.2 parts of basalt medium sand;

the admixture is 1.9 to 1.95 parts of silica powder or fly ash with the activity index of more than 80 percent;

6.9-7 parts of water;

the external additive is a liquid preservative and a water reducing agent, the water reducing agent is 0.23-0.24 part of polycarboxylic acid water reducing agent, and the preservative is 1.34-1.35 parts of sulfate erosion resistant type.

A proportioning optimization method for sulfate erosion preventing concrete comprises the following steps:

(1) determining the components and the proportion of a basic sample and a reference sample for optimization according to the erosion characteristic of sulfate and the parameters of a corrosive environment;

(2) manufacturing test sample assemblies for testing according to different components and proportions, and performing basic maintenance for 28 days, wherein the basic maintenance comprises ordinary maintenance and special maintenance;

(3) considering the influence of external carbonate ions, two samples with the same component and the same proportion are arranged, and the two samples are respectively cured by adopting a standard curing mode and a low-temperature curing mode;

(4) respectively recording maintenance data of the sample in different maintenance durations;

(5) observing the appearance of the sample, and testing the deep components of the sample by an XRD test;

(6) comparing the test results and obtaining the optimal components and proportion of the anti-corrosion concrete according to the test results;

in the step (2), standard maintenance is carried out at room temperature of 20 ℃, and magnesium sulfate solution and 10% limestone powder aqueous solution are adopted for flow infiltration to reach 95% relative humidity;

the low-temperature maintenance in the step (2) is to place the test piece in a solution with the temperature of 4-6 ℃ for immersion maintenance, wherein the solution is a mixed solution of 10% limestone powder aqueous solution and magnesium sulfate solution;

and (2) respectively setting a common sample, an optimized cement sample, an optimized proportioning and optimized cement sample, an internal sulfate ion preparation sample, a carbonate ion invasion sample considered by optimized proportioning and a carbonate ion invasion sample considered by optimized cement according to the corrosion of the C-S-Caulite type sulfate in the step (1).

In the present invention, as an improvement, the composition of the sample in the step (1) is set as follows:

the composition of the common sample was: P.O cement with the strength of 42.5, water, fly ash, limestone, medium sand, a liquid preservative and a water reducing agent;

on the basis of a common sample, replacing cement in the common sample with P.I cement with the strength of 42.5 by the optimized cement sample;

the components of the optimized proportioning sample are as follows: P.O cement with the strength of 42.5, water, fly ash, basalt, medium sand, a liquid preservative and a water reducing agent;

optimizing the mixture ratio and optimizing the components of the cement sample, and replacing the cement in the sample with P.I cement with the strength of 42.5 on the basis of optimizing the mixture ratio;

the components for preparing the sulfate ion sample inside are as follows: P.O cement with the strength of 42.5, water, limestone powder, limestone, medium sand and a water reducing agent.

In the invention, as an improvement, the proportion of the sample is as follows:

the common samples comprise the following components in parts by weight: 393 parts of P.O cement with the strength of 42.5, 200 parts of water, 48 parts of fly ash, 934 parts of limestone, 796 parts of medium sand, 32.5 parts of a liquid preservative, 3.84 parts of a water reducing agent and the water-cement ratio of 0.45;

optimizing a cement sample, on the basis of a common sample, replacing 393 parts of P.I cement with the strength of 42.5 by cement in the common sample;

the mass parts of the optimized proportioning samples are as follows: P.O cement with the strength of 42.5, 168 parts of water, 47 parts of fly ash, 940 parts of basalt, 801 parts of medium sand, 32.5 parts of liquid preservative, 5.64 parts of water reducing agent and the water-cement ratio of 0.36;

optimizing the mixture ratio and optimizing the cement sample, and replacing 422 parts of P.I cement with the strength of 42.5 in the cement sample with the optimized mixture ratio;

the sulfate ion sample prepared inside comprises the following components in parts by weight: P.O parts of cement with the strength of 42.5, 190 parts of water, 47 parts of limestone powder, 864 parts of limestone, 974 parts of medium sand, 5.64 parts of a water reducing agent and the water-cement ratio of 0.35;

during 28 days of basic maintenance, the samples are subjected to common maintenance by spraying aqueous solution;

the optimized proportion considers that carbonate ions invade the sample as the optimized proportion sample, and limestone powder aqueous solution with the concentration of 10% is adopted for spray maintenance in 28-day basic maintenance, so that the sample is specially maintained;

optimizing cement, taking carbonate ions into consideration to invade a sample as an optimized proportion, and optimizing the spraying maintenance of the cement sample by adopting a limestone powder aqueous solution with the concentration of 10% in 28-day basic maintenance, wherein the special maintenance is carried out;

in the present invention, as an improvement, the curing time in the step (3) is 1 month, 3 months, 6 months, 9 months and 12 months, respectively.

The tunnel lining is designed in a full-ring closed mode, surrounding rocks at the periphery of the lining are blocked by grouting, the anti-corrosion concrete impermeability grade of the primary lining of the tunnel is greater than P6, the anti-corrosion concrete impermeability grade of the secondary lining is greater than P8, and the anti-corrosion coefficient of the anti-corrosion concrete in the lining is greater than 0.8.

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

(1) the method is characterized by simulating an actual proportioning test of engineering, combining a special corrosion environment of a weak water permeability gypsum rock stratum, reproducing the whole process of sulfate type corrosion and analyzing corrosion causes, providing a theoretical basis for selection and composition design of an anti-corrosion concrete material, and setting components and proportioning of a sample in the test according to the current situation of the engineering and corrosion characteristics.

(2) Reveal the anticorrosive concrete component and the proportion in special stratum region through the experiment, the contrast test of this application is when considering outside sulphate to corrode, according to outside corrosion environment increase carbonate ion's influence factor to make comprehensive corrosion assessment to actual engineering environment.

(3) Through experimental analysis verification, the prevention of the corrosion of the C-S-Caulite type sulfate is more concise and effective, materials are conveniently obtained, other expensive special materials are not required to be additionally added, the engineering application is more facilitated, the engineering cost is saved, the basalt aggregate is adopted, the long-term performance of the strength and the bearing capacity of the concrete structure is effectively maintained, and the durability of the engineering structure is improved.

Drawings

In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.

FIG. 1 is a schematic structural diagram of XRD test results of samples at 6 months of age in accordance with one embodiment of the present invention;

FIG. 2 is a structural diagram of XRD test results of samples at 9 months of age in accordance with one embodiment of the present invention;

FIG. 3 is a structural diagram of XRD test results of 11-month-old samples according to a first embodiment of the present invention;

FIG. 4 is a structural diagram of XRD test results of samples at 12 months of age in accordance with one embodiment of the present invention;

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.

A proportioning optimization test method for sulfate erosion preventing concrete is characterized in that the first step of the optimization method is to determine the components and the proportioning of an optimization test sample and a comparison sample according to the erosion characteristics of a C-S-Ca type sulfate and corrosion environment parameters, and the method comprises the following steps:

(1) according to the characteristics of the sulfoxonotlite type sulfate corrosion in the existing research, the test sample is considered from two aspects, namely the external sulfate corrosion and the generation of sulfate ions in the concrete, and the test sample is set according to the following modes:

1) setting a basic comparison sample;

2) setting a sample containing no lime substances in cement and aggregate components;

3) the external additive does not contain a sample capable of generating sulfate ions or sulfate ions;

4) consider a sample with external sulfate ions or the intrusion of sulfate ions.

(2) There are 7 groups of basic samples and comparative samples, which include: ordinary sample, optimization cement sample, optimization ratio and optimization cement sample, inside preparation sulfate ion sample, optimization ratio consider sulfate ion invasion sample and optimization cement consider sulfate ion invasion sample, the setting of sample can embody the influence of different components to the erosion reaction on one hand, on the other hand can embody the reaction process under different ratio conditions through optimizing the ratio to find the optimum anticorrosion effect.

(3) And determining the components and the proportion of the sample according to the test requirements of the sample and by combining the actual corrosion environment and geological parameters of the project.

The common sample is a component and a mixture ratio which are commonly used in tunnel lining engineering, the mixture ratio is not adjusted according to sulfate erosion, and the component and the mixture ratio of the common sample comprise 393 parts of P.O cement with the strength of 42.5, 200 parts of water, 48 parts of fly ash, 934 parts of limestone, 796 parts of medium sand, 32.5 parts of a liquid preservative, 3.84 parts of a water reducing agent, and the water-cement ratio is 0.45;

according to the step (1), optimizing a cement sample, replacing P.O cement in the ordinary sample by 393 parts of P.I cement with the strength of 42.5 on the basis of the ordinary sample;

the components and the mixture ratio of the optimized mixture sample comprise 422 parts of P.O cement with the strength of 42.5, 168 parts of water, 47 parts of fly ash, 940 parts of basalt, 801 parts of medium sand, 32.5 parts of liquid preservative, 5.64 parts of water reducing agent, and the water-cement ratio is 0.36, the content of the cement and the water is adjusted according to the water seepage characteristic of a rock stratum in a corrosive environment, the water-cement ratio is changed, and meanwhile, the sulfate erosion effect is influenced by the water-cement ratio, so that the purpose of the required anti-corrosion test is achieved;

optimizing the mixture ratio and optimizing the cement sample, and replacing 422 parts of P.I cement with the strength of 42.5 in the cement sample with the optimized mixture ratio;

the proportion of the sulfate ion sample prepared inside is as follows: P.O cement with the strength of 42.5, 190 parts of water, 47 parts of limestone powder, 864 parts of limestone, 974 parts of medium sand, 5.64 parts of a water reducing agent, the water-cement ratio of 0.35 and sulfate ions in the components of the sample are contained, so that the corrosion effect of the sample from inside to outside is tested;

the optimized proportioning takes the sulfate ion invasion sample into consideration, and the optimized cement takes the sulfate ion invasion sample into consideration, so that the sulfate ion invasion is reflected from the outside.

The second step is that: manufacturing test sample assemblies for testing according to different components and proportions, and performing basic maintenance for 28 days, wherein the basic maintenance comprises ordinary maintenance and special maintenance;

in 28 days of basic maintenance, the basic maintenance of the common sample, the optimized cement sample, the optimized proportion and the optimized cement sample and the internally prepared sulfate ion sample adopts a water solution spraying mode, and is a conventional maintenance mode;

the optimal proportion considers that sulfate ions invade the sample, and the sample is the optimal proportion and is sprayed and maintained by limestone powder aqueous solution with the concentration of 10% in 28-day basic maintenance, and is special maintenance, so that external sulfate ions are invaded;

optimizing cement, taking sulfate ion invasion into a sample into consideration as an optimized proportion, and optimizing the spraying maintenance of the cement sample by adopting a 10% limestone powder aqueous solution in 28-day basic maintenance, and also performing special maintenance;

the third step: considering the influence of external carbonate ions, two samples with the same component and the same proportion are arranged, and the two samples are respectively subjected to a maintenance test in a standard maintenance mode and a low-temperature maintenance mode;

the standard maintenance is that under the condition of room temperature of 20 ℃, magnesium sulfate solution and 10% limestone powder aqueous solution are adopted for flowing infiltration to reach 95% relative humidity;

the low-temperature maintenance is to place the test piece in a solution with the temperature of 4-6 ℃ for immersion maintenance, wherein the solution is a mixed solution of 10% limestone powder aqueous solution and magnesium sulfate solution;

the standard maintenance and the low-temperature maintenance are both corrosion conditions of the lining in actual engineering, the two maintenance modes simulate the corrosion environment in natural conditions, the corrosion process is reproduced, and the corrosion of the C-S-Ca-stone sulfate can be carried out under two conditions of room temperature and low temperature in the weak water permeability gypsum rock stratum.

The fourth step: and respectively recording maintenance data of the sample in different maintenance durations, wherein the maintenance durations of the recorded data are respectively 1 month, 3 months, 6 months, 9 months and 12 months.

The fifth step: and observing the appearance of the sample, and carrying out XRD test to test the deep-layer components of the sample.

The fourth step and the fifth step are both conventional test data testing and detecting steps, and the required instruments and equipment are also the existing equipment.

And a sixth step: and comparing the test results, obtaining the optimal components and proportion of the anti-corrosion concrete according to the test results, finding out the optimal components and proportion of the anti-corrosion concrete after comparing a plurality of groups of test data, and determining the components and proportion of the anti-corrosion concrete used in the engineering according to the current situation of the engineering.

Through the tests, the components and the proportion of the sulfate corrosion prevention concrete for engineering under special conditions can be obtained, and the concrete is prepared by mixing and stirring a base material, an aggregate, an admixture, an external additive and water;

the base material is 17.4 to 17.5 parts of ordinary Portland cement with the strength grade of 42.5;

the aggregate comprises fine aggregate and coarse aggregate, the coarse aggregate is basalt with the particle size of 5-10mm, the fine aggregate is basalt medium sand, and 38.9 parts of basalt and 33.1-33.2 parts of basalt medium sand are included;

the admixture is silica powder or fly ash with an activity index of more than 80 percent, and 1.9 to 1.95 parts;

the external additive is a liquid preservative and a water reducing agent which do not generate sulfate ions or sulfate ions, the water reducing agent is 0.23-0.24 part of polycarboxylic acid water reducing agent, and the preservative is 1.34-1.35 parts of sulfate erosion resistant type; 6.9-7 parts of water.

The design method for applying the sulfate erosion resistant concrete to the tunnel lining is characterized in that the tunnel lining is designed in a full-ring closed mode, surrounding rocks at the periphery of the lining are subjected to grouting water blocking, the anti-corrosion concrete impermeability grade of the primary lining of the tunnel is greater than P6, the anti-corrosion concrete impermeability grade of the secondary lining is greater than P8, and the corrosion resistance coefficient of the anti-corrosion concrete in the lining is greater than 0.8.

The first embodiment is as follows: in this embodiment, the experiment is performed according to the corrosive environment of sulfate-type corrosion of the primary concrete of the dugong tunnel, taking the TSA destruction process of the dugong tunnel as an example.

The geological conditions of Dugong ridge tunnel engineering are limestone and gypsum rock strata with weak water permeability, TSA damages the influence of underground water and damages the cement adhesiveness in concrete, and the water-cement ratio is adjusted on the basis of the existing concrete proportion by considering the geological conditions and the water permeability, so that the comparative anti-corrosion test with the existing concrete proportion is realized.

1. According to the TSA destruction characteristics, two kinds of cement and two kinds of stones are selected in the test for designing the mixing ratio, and the cement is as follows: P.O42.5 and P.I42.5, the pebble is limestone and basalt, the influence of the infiltration of external sulfate ions on the generation of the calcium carbothiosilicate is fully considered, the maintenance condition of 10 percent limestone powder solution is designed, and 7 concrete mixing proportion test samples are tested, wherein the test comprises the following steps: ordinary sample, optimization cement sample, optimize proportion sample, optimize the proportion and optimize the cement sample, inside preparation sulfate ion sample, optimize the proportion and consider sulfate ion invasion sample and optimize the cement and consider sulfate ion invasion sample, and specific sample component and mix proportion are shown in the following table:

concrete TSA test scheme

2. Concrete samples were made according to the test requirements as follows:

(1) concrete test blocks (40 x 160mm) were formed into 18 bars of moulds (10 bars for testing and 8 bars for future use) according to the concrete mix ratio.

(2) After the concrete mixture ratio was stirred, 18 blocks of stone molded (40 × 40mm) were removed by screening.

(3) The slurry was stirred to form 18 blocks (40 × 40mm) of test blocks according to the gelled composition and ratio of the concrete mix.

After the sample is manufactured, in basic maintenance for 28 days, the samples 1-5 are maintained normally, and the samples 6 and 7 are maintained by spraying limestone powder aqueous solution with the concentration of 10%.

In order to fully consider the influence of external carbonate ion permeation on the performance of the concrete, two curing modes, namely standard curing and low-temperature curing, are adopted after 28 days of basic curing.

The standard maintenance is that under the condition of room temperature of 20 ℃, magnesium sulfate solution and 10% limestone powder aqueous solution are adopted for flowing infiltration to reach 95% relative humidity;

the low-temperature curing is to place the test piece in a solution with the temperature of 4-6 ℃ for immersion curing, and the solution is a mixed solution of 10% limestone powder aqueous solution and magnesium sulfate solution.

3. Analysis of test results

After the concrete sample is cured, mechanical experiments, appearance and microscopic analysis are respectively carried out for 1 month, 3 months, 6 months, 9 months and 12 months, wherein the flexural strength of the concrete sample is tested by mechanical experiment equipment, and the external surface and internal states of the concrete sample are tested by infrared and thermal analysis test equipment.

Observing appearance change, taking a picture for sampling, and analyzing the phenomena of crack generation, structural integrity and the like of the sample so as to analyze the influence trend of the generation of internal damage on the appearance of the sample;

the concrete sample strength testing method has the advantages that mechanical testing is carried out through experimental equipment, curing conditions have certain influence on development of concrete sample strength, compressive strength and rupture strength show a descending trend in low-temperature curing, and corresponding corrosion resistance coefficients are reflected, and the concrete is shown in the following table:

mechanical property change of the sample at 6 months under low-temperature curing condition

Change of mechanical properties of the sample at 12 months under low-temperature curing conditions

Compared with the standard maintenance condition, the low-temperature condition slows down the development of the mechanical property of the sample. With the same sample, the compressive strength, the flexural strength and the corresponding corrosion resistance coefficient all show a descending trend along with the extension of the age.

In order to further verify the deep reasons of appearance change and mechanical property development of each sample, XRD tests are carried out on samples with different compositions, and the results are shown in figures 1-4;

under the test conditions, the sample No. 5 begins to appear the typical characteristics of TSA destruction at 9 months, such as appearance cracks, structural peeling, serious reduction of the corrosion resistance coefficient, and the typical characteristic peak of TSA found in the XRD fine modification result, which indicates that the sample has high possibility of TSA destruction and weak resistance.

When the soaking time was 9 months, significant sulfate attack had occurred on sample No. 1, but no calc sulfide had occurred in the corrosives. When the soaking time was 11 months, about 4.11% of the carbo-sulfowollastonite had appeared in the corrosive substance, and this result indicates that the concrete used in sample No. 1, if it encountered a high-concentration sulfate service environment and had poor impermeability by itself, would accelerate the sulfate-type corrosion of the concrete due to the high-concentration sulfate that invaded into the interior of the concrete.

The comparison of test sample No. 2 and test sample No. 5 shows that the addition of stone powder in the concrete material has more obvious influence on the generation of the calcium carbothiosilicate; comparison of test sample No. 5 with test sample No. 6 shows that the influence of carbonate ions in the external environment has a weaker influence on TSA.

And comparing the comprehensive experimental data to obtain the optimal proportion of the No. 4 sample for preventing the sulfate corrosion.

A concrete test piece is prepared by adopting the No. 4 component and the proportion, is soaked in a box body containing the gypsum rock and is placed in a tunnel until the construction of the on-site tunnel is finished, the gypsum rock used in the test piece soaking solution comes from the surrounding rock of the tunnel, and the gypsum content is more than 90%. In the test process, the appearance change of the concrete is observed and the corrosive components are tested at different periods respectively, the soaking time is 20 months, the XRD pattern of the mortar layer on the surface layer of the concrete is obtained, and the test result shows that no obvious ettringite and merwinite are detected in the mortar layer on the surface layer, which shows that the concrete adopted by the disease control has higher sulfate erosion resistance.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.