Baseplane-treatment-free cement-based coating for tunnel leakage water treatment and preparation method of base-treatment-free cement-based coating

Abstract

The invention discloses a base-surface-treatment-free cement-based coating for tunnel leakage water treatment and a preparation method of the base-surface-treatment-free cement-based coating. According to the waterproof coating for tunnel construction, the cement serves as a base material, the coal ash, the slag, the calcium hydroxide and the quartz sand are combined, under the action of the interface agent and the crystallizing agent, water leakage positions can be treated, complex pretreatment on a base plane is not needed while the bonding strength with the base plane is guaranteed, and the problem that the base plane pretreatment procedure of an existing waterproof coating for tunnel construction is tedious is solved; the tunnel leakage water treatment is realized, the construction period is shortened by more than 90%, and the treatment efficiency is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of waterproof coatings, and specifically to a surface treatment-free cement-based coating for tunnel leakage treatment and a preparation method thereof. Background Art

[0002] Water leakage is the most common disease in tunnel engineering, which seriously endangers the structural safety and operational safety of the project. On the one hand, long-term water leakage erodes the tunnel lining structure, dissolves alkaline substances in the concrete, and reduces its strength and durability; and in cold areas, repeated freezing and thawing of water leakage will cause cracking and peeling of the lining, threatening the overall stability of the tunnel structure. On the other hand, water leakage makes the road surface slippery and increases the risk of traffic accidents. In addition, if it leaks near electrical equipment, it may cause a short circuit, paralyzing the lighting, ventilation and other systems, and affecting the normal operation of the tunnel. Therefore, efficient management of tunnel water leakage is crucial to ensuring the safety of tunnel structure and operation and improving the quality of tunnel engineering services.

[0003] With the continuous growth of traffic volume, the operating pressure of tunnels is increasing day by day. In order to ensure the normal operation of traffic, the time (i.e., window period) for interrupting tunnel traffic to carry out comprehensive and thorough water leakage treatment is very limited. Usually, the window period is only a few hours in the early morning, and the interval between adjacent window periods may be several days. Therefore, the convenience of using water leakage treatment materials is particularly important at this time.

[0004] Existing waterproof coatings often have strict pretreatment requirements for the construction base surface. Before the coating is used, it is necessary to go through treatment methods such as patching, grinding, flushing, and wetting to ensure that the construction base surface is flat, dust-free, and has a certain degree of wetting or dryness. In the tunnel water leakage scenario, due to the long-term influence of physical and chemical effects such as water dissolution and operational dust on the base surface, the base surface pretreatment time of existing coatings is as long as several hours or even days. It is often impossible to complete the entire process of water leakage control within a skylight period, which seriously limits the efficiency of water leakage control. If the pretreatment does not meet the requirements, the low bonding strength between the coating and the base surface will cause the coating to peel off during tunnel operation, which will have a serious impact on the safety of tunnel operation. Summary of the invention

[0005] Based on the above reasons, the first purpose of the present invention is to provide a cement-based coating that does not require base surface treatment for tunnel water leakage treatment. When used for tunnel water leakage treatment, it can eliminate the pretreatment step of the seepage base surface during the treatment process and improve the efficiency of tunnel water leakage treatment.

[0006] The second object of the present invention is to provide a method for preparing a cement-based coating that does not require surface treatment and is used for tunnel water leakage treatment.

[0007] The first object of the present invention can be achieved by adopting the following technical solutions:

[0008] A surface treatment-free cement-based coating for tunnel water leakage treatment, comprising the following components in parts by weight:

[0009]

[0010] The interface agent is a mixture of oxalic acid, tartaric acid and citric acid; the crystallizing agent is a mixture of sodium sulfate, sodium silicate and potassium aluminum sulfate.

[0011] Furthermore, the invention also includes 0.1-0.2 parts of water retaining agent and 0.1-0.2 parts of water reducing agent by weight.

[0012] Furthermore, the silicate cement is PO42.5 grade silicate cement; and the sulphoaluminate cement is fast-hardening sulphoaluminate cement.

[0013] Furthermore, the fly ash is Class I fly ash; the slag is S95 grade granulated blast furnace slag powder with a specific surface area of ​​350-450m 2 / kg; the fineness of the quartz sand is 40-70 mesh.

[0014] Furthermore, the mass ratio of oxalic acid, tartaric acid and citric acid is (0.1-1):(3-5):(0.2-0.5).

[0015] Furthermore, the mass ratio of the sodium sulfate, sodium silicate and potassium aluminum sulfate is 1:(3-4):(2.5-3.5).

[0016] Furthermore, the water-retaining agent is a mixture of polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose; the mass ratio of the polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose is (0.5-2.5):(8-10).

[0017] Furthermore, the water reducing agent is a polycarboxylic acid water reducing agent; the water reducing rate of the water reducing agent is 25% to 30%.

[0018] The second object of the present invention can be achieved by adopting the following technical solutions:

[0019] The preparation method of the above-mentioned cement-based coating for tunnel leakage treatment without substrate treatment comprises the following steps:

[0020] Step S1, mixing silicate cement, sulphoaluminate cement, fly ash, slag and calcium hydroxide to obtain a mixed powder;

[0021] Step S2, adding quartz sand to the mixed powder and continuing to stir and mix to obtain material A.

[0022] Step S3, stirring and mixing the interface agent, water retaining agent, crystallizing agent and water reducing agent to obtain material B;

[0023] Step S4, material A and material B are stirred and mixed to obtain a cement-based coating that does not require base surface treatment and is used for tunnel water leakage treatment.

[0024] Furthermore, the stirring conditions in step S1 are: stirring at 15-30° C. and 50-100 r / min for 15-30 min;

[0025] The stirring conditions in step S2 are: stirring at 15-30° C. and 50-100 r / min for 30-45 min;

[0026] The stirring conditions in step S3 are: stirring at 15-30° C. and 100-200 r / min for 5-10 min;

[0027] The stirring conditions in step S4 are: stirring at 15-30° C. and 100-150 r / min for 15-30 min.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The surface treatment-free cement-based coating for tunnel water leakage treatment of the present invention uses cement as the base material, combined with fly ash, slag, calcium hydroxide and quartz sand. Under the action of an interface agent and a crystallizing agent, it can treat water leakage, while ensuring the bonding strength with the base surface, without the need for complex pretreatment of the base surface; it not only achieves tunnel water leakage treatment, but also shortens the construction period and significantly improves the treatment efficiency.

[0030] 2. The preparation method of the surface treatment-free cement-based coating for tunnel water leakage treatment of the present invention processes the raw materials separately according to different combinations, which is beneficial to the overall performance of the coating; and it can be prepared by physical mixing, and can be prepared and used immediately, which is convenient for the treatment of water leakage at any time. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Tunnels are becoming more and more common in road infrastructure construction, and the problem of tunnel water leakage is a problem that must be faced. Tunnel water leakage is highly harmful and has a great impact on construction during treatment, which seriously affects the safety of tunnel operations. Although some of the currently used waterproof materials can play a role in leak repair, finding a better coating is still one of the directions for tunnel water leakage treatment. Therefore, the present application provides a base surface treatment-free cement-based coating and a preparation method for tunnel water leakage treatment, which improves the efficiency of tunnel water leakage treatment while achieving good bonding strength with the base surface.

[0033] A surface treatment-free cement-based coating for tunnel water leakage treatment, comprising the following components in parts by weight:

[0034]

[0035]

[0036] The interface agent is a mixture of oxalic acid, tartaric acid and citric acid; the crystallizing agent is a mixture of sodium sulfate, sodium silicate and potassium aluminum sulfate.

[0037] With cement as the base material, combined with fly ash, slag, calcium hydroxide and quartz sand, under the action of interface agent and crystallizer, water leakage can be treated; oxalic acid, tartaric acid and citric acid are ionized after being mixed with water, and the generated anions can complex calcium ions and further slightly dissolve the base surface, which has the effect of chemically grinding the base surface. Sodium sulfate, sodium silicate and potassium aluminum sulfate provide silicate, sulfate and aluminum ions for the hydration reaction at the interface, promote the formation of reaction products and increase the interfacial bonding strength. In this way, while ensuring the bonding strength with the base surface, there is no need to perform complex pretreatment of the base surface; that is, the base surface bonding strength similar to that of the base surface after the full process pretreatment of the base surface is achieved, and the efficiency of tunnel leakage treatment is improved.

[0038] As one embodiment thereof, the invention further comprises 0.1-0.2 parts by weight of a water retaining agent and 0.1-0.2 parts by weight of a water reducing agent.

[0039] The water retaining agent can increase the consistency of the coating after mixing, improve the water stability in the coating, avoid excessive water loss of the coating due to the drying of the base surface, and ensure that the coating has sufficient reaction time with the base surface under water-rich conditions. The water reducing agent can reduce the amount of water used for mixing the coating, further reduce the amount of water, and accelerate the drying speed of the base surface.

[0040] As one embodiment, the silicate cement is PO42.5 grade silicate cement; the sulphoaluminate cement is fast-hardening sulphoaluminate cement.

[0041] As one embodiment, the fly ash is Class I fly ash; the slag is S95 grade granulated blast furnace slag powder with a specific surface area of ​​350-450m 2 / kg; the fineness of the quartz sand is 40-70 mesh.

[0042] As one embodiment thereof, the mass ratio of oxalic acid, tartaric acid and citric acid is (0.1-1):(3-5):(0.2-0.5).

[0043] As one embodiment, the mass ratio of sodium sulfate, sodium silicate and potassium aluminum sulfate is 1:(3-4):(2.5-3.5).

[0044] As one embodiment, the water retaining agent is a mixture of polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose; the mass ratio of the polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose is (0.5-2.5): (8-10). Hydroxypropyl methylcellulose is an excellent water retaining agent, and polyethylene-vinyl acetate copolymer emulsion has excellent water resistance, acid and alkali resistance and weather resistance, which can enhance the resistance of the coating. As a high molecular polymer, it can also be used with hydroxypropyl methylcellulose in a small amount to increase the consistency of the coating after mixing of the present invention; as a method of improving the moisture stability in the coating, avoiding excessive water loss of the coating due to drying of the base surface, and ensuring that the coating has sufficient reaction time with the base surface under water-rich conditions.

[0045] As one embodiment, the water reducer is a polycarboxylic acid water reducer; the water reduction rate of the water reducer is 25% to 30%.

[0046] The present application also provides a method for preparing the above-mentioned cement-based coating without base surface treatment for tunnel leakage treatment, comprising the following steps:

[0047] Step S1, mixing silicate cement, sulphoaluminate cement, fly ash, slag and calcium hydroxide to obtain a mixed powder;

[0048] Step S2, adding quartz sand to the mixed powder and continuing to stir and mix to obtain material A.

[0049] Step S3, stirring and mixing the interface agent, water retaining agent, crystallizing agent and water reducing agent to obtain material B;

[0050] Step S4, material A and material B are stirred and mixed to obtain a cement-based coating that does not require base surface treatment and is used for tunnel water leakage treatment.

[0051] As one embodiment, the stirring condition in step S1 is: stirring at 15-30° C. and 50-100 r / min for 15-30 min;

[0052] As one embodiment, the stirring condition in step S2 is: stirring at 15-30° C. and 50-100 r / min for 30-45 min;

[0053] As one embodiment, the stirring conditions in step S3 are: stirring at 100-200 r / min for 5-10 min at 15-30° C.;

[0054] As one embodiment, the stirring condition in step S4 is: stirring at 100-150 r / min for 15-30 min at 15-30° C.

[0055] The following is a further description with reference to specific embodiments.

[0056] Example 1

[0057] A surface treatment-free cement-based coating for tunnel water leakage treatment, comprising the following components in parts by weight:

[0058] 40 parts of Portland cement; 15 parts of sulphoaluminate cement; 4 parts of fly ash; 4 parts of slag; 2 parts of calcium hydroxide; 33 parts of quartz sand; 0.3 parts of interface agent; 0.1 parts of water retaining agent; 1.5 parts of crystallizing agent; 0.1 parts of water reducing agent;

[0059] The interface agent used is a mixture of oxalic acid, tartaric acid and citric acid in a mass ratio of 0.2:4:0.4; the water retaining agent used is a mixture of polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose in a mass ratio of 1:8; the crystallizing agent used is a mixture of sodium sulfate, sodium silicate and potassium sulfoaluminate in a mass ratio of 1:3:3; the silicate cement is PO42.5 grade silicate cement; the sulfoaluminate cement is fast-hardening sulfoaluminate cement; the fly ash is grade I fly ash; the slag is S95 grade granulated blast furnace slag powder with a specific surface area of ​​400m 2 / kg; quartz sand fineness is 40-70 mesh;

[0060] The preparation method is:

[0061] The silicate cement, sulphoaluminate cement, fly ash, slag and calcium hydroxide were stirred and mixed at 100 r / min for 30 min at room temperature to obtain a mixed powder;

[0062] Quartz sand was added to the mixed powder, and the mixture was stirred at 100 r / min for 30 min at room temperature to obtain material A.

[0063] The interface agent, water retaining agent, crystallizing agent and water reducing agent were stirred and mixed at room temperature at 100 r / min for 10 min to obtain material B;

[0064] Material A and material B were mixed by stirring at 100 r / min for 30 min at room temperature to obtain a cement-based coating without substrate treatment for tunnel leakage treatment.

[0065] Example 2

[0066] The difference between Example 2 and Example 1 is that the interface agent is 0.4 parts by weight; the other components and preparation method are the same as those of Example 1.

[0067] Example 3

[0068] The difference between Example 3 and Example 1 is that the interface agent is 0.5 parts by weight; the other components and preparation method are the same as those of Example 1.

[0069] Example 4

[0070] The difference between Example 4 and Example 1 is that the water retaining agent is 0.15 parts by weight; the other components and preparation method are the same as those of Example 1.

[0071] Example 5

[0072] The difference between Example 5 and Example 1 is that the water retaining agent is 0.2 parts by weight; the other components and preparation method are the same as those of Example 1.

[0073] Example 6

[0074] The difference between Example 6 and Example 1 is that the crystallization agent is 2 parts by weight; the other components and preparation method are the same as those of Example 1.

[0075] Example 7

[0076] The difference between Example 7 and Example 1 is that the crystallizing agent is 2.5 parts by weight; the other components and preparation method are the same as those of Example 1.

[0077] Example 8

[0078] The difference between Example 8 and Example 1 is that the amount of silicate cement is 35 parts by weight; the amount of sulphoaluminate cement is 20 parts by weight; and the other components and preparation method are the same as those of Example 1.

[0079] Example 9

[0080] The difference between Example 9 and Example 1 is that the amount of silicate cement is 50 parts by weight; the amount of sulphoaluminate cement is 5 parts by weight; and the other components and preparation method are the same as those of Example 1.

[0081] Example 10

[0082] The difference between Example 10 and Example 1 is that fly ash is 3 parts by weight; slag is 5 parts by weight; calcium hydroxide is 3 parts by weight; water reducer is 0.2 parts by weight; other components and preparation method are the same as those in Example 1.

[0083] Embodiment 11

[0084] The difference between Example 11 and Example 1 is that fly ash is 5 parts by weight; slag is 3 parts by weight; calcium hydroxide is 4 parts by weight; other components and preparation method are the same as those in Example 1.

[0085] Example 12

[0086] The difference between Example 12 and Example 1 is that the interfacial agent used is a mixture of oxalic acid, tartaric acid, and citric acid in a mass ratio of 0.1:5:0.4; the water-retaining agent used is a mixture of polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose in a mass ratio of 0.5:10; the crystallizing agent used is a mixture of sodium sulfate, sodium silicate, and potassium sulfoaluminate in a mass ratio of 1:4:3; and the other components and preparation method are the same as those in Example 1.

[0087] Embodiment 13

[0088] The difference between Example 13 and Example 1 is that the interfacial agent used is a mixture of oxalic acid, tartaric acid, and citric acid in a mass ratio of 1:5:0.2; the water-retaining agent used is a mixture of polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose in a mass ratio of 1:9; the crystallizing agent used is a mixture of sodium sulfate, sodium silicate, and potassium sulfoaluminate in a mass ratio of 1:3:3.5; the other components and preparation method are the same as those in Example 1.

[0089] Embodiment 14

[0090] The difference between Example 14 and Example 1 is that the interfacial agent used is a mixture of oxalic acid, tartaric acid, and citric acid in a mass ratio of 0.5:4:0.5; the water-retaining agent used is a mixture of polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose in a mass ratio of 2.5:8; the crystallizing agent used is a mixture of sodium sulfate, sodium silicate, and potassium sulfoaluminate in a mass ratio of 1:3:2.5; and the other components and preparation method are the same as those in Example 1.

[0091] Comparative Example 1

[0092] The difference between Comparative Example 1 and Example 1 is that the interface agent is 0 parts by weight; the other components and preparation method are the same as those of Example 1.

[0093] Comparative Example 2

[0094] The difference between Comparative Example 2 and Example 1 is that the water retaining agent is 0 parts by weight; the other components and preparation method are the same as those of Example 1.

[0095] Comparative Example 3

[0096] The difference between Comparative Example 3 and Example 1 is that the crystallization agent is 0 parts by weight; the other components and preparation method are the same as those of Example 1.

[0097] Comparative Example 4

[0098] The difference between Comparative Example 4 and Example 1 is that the crystallizing agent, the water-retaining agent and the interface agent are all 0 parts by weight; the other components and the preparation method are the same as those of Example 1.

[0099] Comparative Example 5

[0100] The difference between Comparative Example 5 and Example 1 is that the interfacial agent used is a mixture of tartaric acid and citric acid with a mass ratio of 10:1; the other components and preparation method are the same as those in Example 1.

[0101] Comparative Example 6

[0102] The difference between Comparative Example 6 and Example 1 is that the interface agent used is oxalic acid; the other components and preparation method are the same as those of Example 1.

[0103] Comparative Example 7

[0104] The difference between Comparative Example 7 and Example 1 is that the water retaining agent used is polyethylene-vinyl acetate copolymer emulsion; other components and preparation methods are the same as those in Example 1.

[0105] Comparative Example 8

[0106] The difference between Comparative Example 8 and Example 1 is that the water-retaining agent used is hydroxypropyl methylcellulose; the other components and preparation method are the same as those of Example 1.

[0107] Comparative Example 9

[0108] The difference between Comparative Example 9 and Example 1 is that the crystallizing agent used is a mixture of sodium sulfate and sodium silicate with a mass ratio of 1:3; the other components and preparation method are the same as those in Example 1.

[0109] Comparative Example 10

[0110] The difference between Comparative Example 10 and Example 1 is that the crystallizing agent used is a mixture of sodium sulfate and potassium aluminum sulfate in a mass ratio of 1:3; the other components and preparation method are the same as those in Example 1.

[0111] Comparative Example 11

[0112] The difference between Comparative Example 10 and Example 1 is that the crystallizing agent used is a mixture of sodium silicate and potassium aluminum sulfate in a mass ratio of 1:1; the other components and preparation method are the same as those in Example 1.

[0113] The performance testing process of the cement-based coatings for tunnel water leakage treatment without substrate treatment prepared in Examples 1 to 14 and Comparative Examples 1 to 11 is as follows:

[0114] According to GB18445-2012, the flexural strength, compressive strength, wet substrate bonding strength, untreated substrate bonding strength and anti-seepage performance of the non-substrate treatment cement-based coating used for tunnel leakage treatment were tested; the results are shown in Table 1.

[0115] Table 1 Performance of cement-based coatings without surface treatment for tunnel water leakage control

[0116]

[0117]

[0118] Combining Example 1 and Comparative Examples 1-4, it can be seen that the composite application of three functional additives, namely, interface agent, water-retaining agent and crystallizing agent, at appropriate dosages improves the wet base surface bonding strength of cement-based coatings and greatly improves the untreated base surface bonding strength, making it close to or able to reach the wet base surface bonding strength.

[0119] Combining Examples 1-3 and Comparative Example 1, it can be seen that the addition of the interface agent can effectively improve the wet base surface bonding strength and the untreated base surface bonding strength of the cement-based coating, but as the addition amount further increases, the effect of the interface agent in delaying hydration gradually emerges, and the bonding strength decreases.

[0120] Combining Examples 1, 4-5 and Comparative Example 2, it can be seen that the addition of the water retaining agent can effectively improve the wet base surface bonding strength and the untreated base surface bonding strength of the cement-based coating. Within the dosage range of the water retaining agent in this application, the higher the dosage, the higher the bonding strength.

[0121] Combined with Examples 1, 6-7 and Comparative Example 3, it can be seen that the addition of the crystallizer can effectively improve the wet base surface bonding strength and the untreated base surface bonding strength of the cement-based coating. Within the range of the crystallizer dosage of the present application, the change in the crystallizer dosage has no significant effect on the bonding strength.

[0122] In combination with Examples 1, 8-14, it can be seen that within the dosage range of cement, fly ash, slag, calcium hydroxide, water reducer, interface agent, water retaining agent and crystallizing agent protected in the present application, the bonding strength of the untreated base surface of the cement-based coating within the cement content range is greater than or equal to 1.0 MPa, the impermeability pressure ratio with coating is greater than 250%, and the impermeability pressure ratio without coating is greater than 175%, which meets the impermeability performance requirements of GB18445-2012 for waterproof coatings.

[0123] Comparative Examples 7 and 8 illustrate that the use of a single water-retaining agent cannot achieve the effect of using both water-retaining agents in combination in Example 1.

[0124] Comparative Examples 9-11 show that the combination of any two of the crystallizing agents sodium sulfate, sodium silicate, and potassium sulfoaluminate significantly reduces the bonding strength of the coating and the impermeability of the mortar, indicating that the combination of the three synergistically improves the bonding strength and impermeability of the coating.

[0125] Therefore, within the dosage range of the three functional additives protected in this application, the bonding strength of the untreated base surface of the cement-based coating is greater than or equal to 1.0MPa, the impermeability pressure ratio with coating is greater than 250%, and the impermeability pressure ratio without coating is greater than 175%, which meets the impermeability performance requirements of GB18445-2012 for waterproof coatings. Combined with the data of comparative examples 1-4, it can be seen that in the absence of any of the components, the prepared material cannot meet the standard requirements. Combined with comparative examples 5-11, it can be seen that the lack of any specific component in the three types of additives, namely, the interface agent, the water-retaining agent, and the crystallizing agent, will affect the bonding strength of the untreated base surface of the material, making it fail to meet the conditions for free base surface treatment.

[0126] To summarize, the present application is a cement-based coating for tunnel water leakage treatment that does not require base surface treatment. It uses cement as the base material, combined with fly ash, slag, calcium hydroxide and quartz sand. Under the action of an interface agent and a crystallizing agent, it can treat water leakage without complicated pretreatment of the base surface while ensuring the bonding strength with the base surface. It not only achieves tunnel water leakage treatment, but also shortens the construction period by more than 90%, significantly improving the treatment efficiency.

[0127] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A cement-based coating for tunnel leakage treatment without substrate treatment, characterized in that: It comprises the following components in parts by weight: The interface agent is a mixture of oxalic acid, tartaric acid and citric acid; the crystallizing agent is a mixture of sodium sulfate, sodium silicate and potassium aluminum sulfate.

2. The surface treatment-free cement-based coating for tunnel water leakage treatment according to claim 1, characterized in that: The invention also includes 0.1-0.2 parts of water retaining agent and 0.1-0.2 parts of water reducing agent by weight.

3. The surface treatment-free cement-based coating for tunnel water leakage treatment according to claim 1, characterized in that: The silicate cement is PO42.5 grade silicate cement; the sulphoaluminate cement is fast-hardening sulphoaluminate cement.

4. The surface treatment-free cement-based coating for tunnel water leakage treatment according to claim 1, characterized in that: The fly ash is Class I fly ash; the slag is S95 grade granulated blast furnace slag powder with a specific surface area of ​​350-450m 2 / kg; the fineness of the quartz sand is 40-70 mesh.

5. The surface treatment-free cement-based coating for tunnel leakage treatment according to claim 1, characterized in that: The mass ratio of the oxalic acid, tartaric acid and citric acid is (0.1-1):(3-5):(0.2-0.5).

6. The surface treatment-free cement-based coating for tunnel leakage treatment according to claim 1, characterized in that: The mass ratio of the sodium sulfate, sodium silicate and potassium aluminum sulfate is 1:(3-4):(2.5-3.5).

7. The surface treatment-free cement-based coating for tunnel water leakage treatment according to claim 2, characterized in that: The water retaining agent is a mixture of polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose; the mass ratio of the polyethylene-vinyl acetate copolymer emulsion and hydroxypropyl methylcellulose is (0.5-2.5):(8-10).

8. The surface treatment-free cement-based coating for tunnel water leakage treatment according to claim 2, characterized in that: The water reducing agent is a polycarboxylic acid water reducing agent; the water reducing rate of the water reducing agent is 25% to 30%.

9. The method for preparing the surface treatment-free cement-based coating for tunnel leakage treatment according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step S1, mixing silicate cement, sulphoaluminate cement, fly ash, slag and calcium hydroxide to obtain a mixed powder; Step S2, adding quartz sand to the mixed powder and continuing to stir and mix to obtain material A. Step S3, stirring and mixing the interface agent, water-retaining agent, crystallizing agent and water-reducing agent to obtain material B; Step S4, material A and material B are stirred and mixed to obtain a cement-based coating that does not require base surface treatment and is used for tunnel water leakage treatment.

10. The method for preparing the surface treatment-free cement-based coating for tunnel leakage treatment according to claim 9, characterized in that: The stirring conditions in step S1 are: stirring at 15-30° C. and 50-100 r / min for 15-30 min; The stirring conditions in step S2 are: stirring at 15-30° C. and 50-100 r / min for 30-45 min; The stirring conditions in step S3 are: stirring at 15-30° C. and 100-200 r / min for 5-10 min; The stirring conditions in step S4 are: stirring at 15-30° C. and 100-150 r / min for 15-30 min.

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