High-anti-cracking hybrid fiber concrete for railway bridge deck waterproof protective layer and preparation method and application thereof

Abstract

The application discloses a kind of high anti-cracking hybrid fiber concrete for railway bridge deck waterproof protective layer and its preparation method and application, it is related to railway bridge concrete bridge deck waterproof technical field.Per cubic meter concrete includes: cement 260kg~290kg, fly ash 70kg~100kg, fine aggregate 679kg~689kg, coarse aggregate 1111kg~1121kg, water 135kg~140kg, hybrid fiber is respectively 2.8kg~3.2kg or 1.2kg~1.6kg according to different kinds, water reducing agent and air entraining agent are respectively 0.8%~1.2% and 0.5%~1.5% of the total mass of cement and fly ash.The concrete of the application has high crack resistance, high durability, easy construction and strong adaptability to complex environment, overcomes the shortcomings of insufficient crack resistance and durability of traditional fiber fine aggregate concrete for railway bridge deck waterproof protective layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of railway bridge concrete bridge deck waterproofing, more particularly to a high-anti-cracking hybrid fiber concrete for railway bridge deck waterproofing protective layer, and a preparation method and application thereof. BACKGROUND

[0002] To ensure the durability of the railway concrete bridge body structure, a high-ductility flexible waterproof base layer that can adapt to temperature difference and structural deformation is designed on the bridge deck during bridge design, and a high-strength rigid material is used as the protective layer of the flexible waterproof base layer. At present, the design regulation stipulates that the rigid material is fine stone concrete mixed with polyacrylonitrile fiber or polypropylene fiber mesh. Since the bridge deck waterproofing protective layer is directly exposed to the train running space and the external service environment, it needs to have good anti-cracking, anti-permeability and durability to prevent water seepage under the bridge deck, protect the underlying waterproof base material, and ensure the durability of the bridge body and the safety of train operation.

[0003] However, the application effect of the railway bridge deck waterproofing protective layer concrete in China is not very ideal at present, especially in cold winter areas, the phenomenon of concrete cracking, peeling and pulverization often occurs shortly after construction, which has seriously affected the safe operation of China's railways. The main reason for this phenomenon is that, on the one hand, the anti-cracking materials such as polyacrylonitrile fiber or polypropylene fiber mesh stipulated in the current design have weak effect on the plastic anti-cracking of concrete, but have obvious negative impact on the water consumption and workability of concrete; on the other hand, the mix proportion design of the current bridge deck waterproofing protective layer concrete mostly refers to the mix proportion design parameters of ordinary concrete, adopts the technical path of high cementitious material content (>430 kg / m 3 ), high water consumption (>150 kg / m 3 ) and low air content (2%~3%), which leads to high cracking risk and poor durability of the concrete; in addition, since the bridge deck waterproofing protective layer belongs to cast-in-place concrete structure with characteristics such as small thickness and large surface area, the adaptation degree between its construction process and workability requirements is insufficient, and the risk of concrete segregation and bleeding is high, which easily leads to surface cracking.

[0004] At present, there are few relevant patents for the railway bridge deck waterproof protective layer concrete. The content disclosed by Chinese patent CN201611140581.4 is directed to the rapid repair of the railway bridge deck waterproof protective layer, without considering the requirements for the concrete working performance and crack resistance during the initial construction; the concrete containing PVA / PAN fibers disclosed by Chinese patent CN202010150363.9 is not optimized in terms of shrinkage, crack resistance and durability; and the existing disclosed patents do not provide the preparation method of the bridge deck waterproof protective layer concrete. Therefore, how to provide a bridge deck waterproof protective layer concrete material with high crack resistance, improve the working performance, mechanical properties and durability of the bridge deck waterproof protective layer concrete, and enhance the protection of the railway bridge deck waterproof layer and beam structure, is a problem that the person skilled in the art needs to solve urgently. SUMMARY

[0005] The purpose of the present application is to provide a railway bridge deck waterproof protective layer with high crack resistance, and a preparation method and application thereof, so as to solve the problem of easy cracking, peeling or pulverization of the railway bridge concrete deck waterproof protective layer. The railway bridge deck waterproof protective layer with high crack resistance provided by the embodiments of the present application has the characteristics of high crack resistance, high durability and adaptability to rapid construction.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] On the one hand, the present application discloses a railway bridge deck waterproof protective layer with high crack resistance, which comprises the following components per cubic meter of concrete in terms of mass: cement 260kg-290kg, fly ash 70kg-100kg, fine aggregate 679kg-689kg, coarse aggregate 1111kg-1121kg, water 135kg-140kg, hybrid fibers 2.8kg-3.2kg or 1.2kg-1.6kg according to different types, water reducing agent and air entraining agent 0.8%-1.2% and 0.5%-1.5% of the total mass of cement and fly ash, respectively.

[0008] The hybrid fibers include hybrid high-alkali-resistant glass fibers or hybrid polyformaldehyde fibers, 2.8kg-3.2kg of fibers per cubic meter of concrete are added when hybrid high-alkali-resistant glass fibers are used, and 1.2kg-1.6kg of fibers per cubic meter of concrete are added when hybrid polyformaldehyde fibers are used;

[0009] The hybrid high-alkali-resistant glass fibers are composed of 10% of 12mm length dispersion type high-alkali-resistant glass fibers and 90% of 36mm length bundled type high-alkali-resistant glass fibers by mass ratio; and the hybrid polyformaldehyde fibers are composed of 30% of 12mm length dispersion type polyformaldehyde fibers and 70% of 30mm length dispersion type polyformaldehyde fibers by mass ratio;

[0010] The fine aggregate adopts medium-fine sand mixed by medium sand and fine sand in a mass ratio of 1:1;

[0011] The coarse aggregate is prepared by shaping and two-stage combination of 5mm-10mm gravel, 5mm-8mm and 8mm-10mm particle size ranges are obtained by sieving the 5mm-10mm gravel by using a 8mm aperture sieve, and the 5mm-8mm particle size gravel is mixed with the 8mm-10mm particle size gravel in a mass ratio of 8:2, and the porosity of the coarse aggregate after mixing is ≤38%.

[0012] Further, the cement is P.O42.5 ordinary portland cement with an alkali content ≤0.6%, and the fly ash is grade II fly ash, and the total mass of the cement and the fly ash in each cubic meter of concrete is ≤360kg;

[0013] Further, the water reducing agent is a polycarboxylic acid water reducing agent with a water reducing rate ≥30%.

[0014] Further, the slump of the high anti-cracking hybrid fiber concrete is <140mm.

[0015] Further, the air content of the high anti-cracking hybrid fiber concrete is controlled to be 4%-6% by using the air entraining agent.

[0016] In a second aspect, the application further discloses a preparation method of the high anti-cracking hybrid fiber concrete for the waterproof protective layer of the railway bridge deck.

[0017] a. According to the volume of the high anti-cracking hybrid fiber concrete required, prepare each component according to the formula amount;

[0018] b. Put the cement, fly ash, fine aggregate, and coarse aggregate into a mixer, stir uniformly to obtain dry mixture, and continue to stir and gradually add water, water reducing agent, and air entraining agent;

[0019] c. When the hybrid high-alkali-resistant glass fiber is used, the hybrid fiber is added in the following order: the 12mm length of the high-alkali-resistant glass fiber is added into the mixer at the same time as the cement, fly ash, fine aggregate, and coarse aggregate, and the 36mm length of the high-alkali-resistant glass fiber is added into the mixer after the water, water reducing agent, and air entraining agent are stirred in the mixer for 2 minutes;

[0020] d. When the hybrid polyformaldehyde fiber is used, the hybrid fiber is added in the following order: the 12mm length of the polyformaldehyde fiber is added into the mixer at the same time as the cement, fly ash, fine aggregate, and coarse aggregate, and the 30mm length of the polyformaldehyde fiber is added into the mixer after the water, water reducing agent, and air entraining agent are stirred in the mixer for 2 minutes;

[0021] e. After the components are stirred evenly, the high-anti-cracking hybrid fiber concrete for the waterproof protective layer of the railway bridge deck is prepared.

[0022] Further, the total stirring time starts from the time when the water and the water reducing agent are added, and the total stirring time is ≤3 min.

[0023] Further, the stirrer can adopt a vertical shaft planetary concrete mixer or a forced single-cantilever shaft concrete mixer.

[0024] In a third aspect, the application further discloses an application of the high-anti-cracking hybrid fiber concrete for the waterproof protective layer of the railway bridge deck in the construction of the waterproof protective layer of the railway bridge deck, which comprises the following steps:

[0025] (1) distribution, on-site preparation of the hybrid fiber concrete and transportation to the bridge deck distribution point, the number of distribution points in the length range of a single track slab >2;

[0026] (2) paving and vibrating, uniform paving of the concrete, vibrating of the concrete using a mobile vibrating device, and supplementary vibration of the concrete near the track slab using a small flat vibrator;

[0027] (3) rough finishing: smoothing and grouting of the vibrated concrete using a plastic trowel, finishing from the middle to both sides, ensuring that the transverse drainage slope gradient is ≥4% and the longitudinal water collection slope gradient is ≥3‰, and setting a transverse joint every 4 m along the longitudinal direction;

[0028] (4) fine finishing: twice fine finishing of the concrete after the rough finishing using a steel trowel, and the interval between the two times of fine finishing is 5 min;

[0029] (5) curing: after the construction of the protective layer concrete is completed for 30 min, spraying of the concrete curing liquid on the surface, the spraying frequency >2, and the dosage of the concrete curing liquid each time is 400 g / m 2 ;

[0030] (6) sealing: sealing of the transverse joint using a silicone caulking glue.

[0031] Further, the temperature of the concrete when being transported to the bridge deck distribution point is ≥5℃.

[0032] Further, the walking speed of the mobile vibrating device is <1.5 m / min.

[0033] Further, the thickness of the protective layer concrete after paving and vibrating is ≥40 mm, and the material is supplemented on the surface when the paving thickness is insufficient, and the mobile vibrating device is opened back for secondary vibration.

[0034] Further, the specific way of sealing the transverse joint by using the silicone sealant is that interface agent is applied on the concrete surface on both sides of the transverse joint, a polyethylene foam rod with a circular cross section and a diameter same as the width of the transverse joint is used as a supporting material to fill the lower part of the transverse joint, and the silicone sealant is filled on the upper part of the polyethylene foam rod, and the width-thickness ratio of the silicone sealant is greater than 1.

[0035] Compared with the prior art, the application has the following beneficial effects:

[0036] The high-anti-cracking hybrid fiber concrete for the waterproof protective layer of a railway bridge deck has high anti-cracking property, high durability, easy construction property and strong adaptability to different environments, and overcomes the defects of the traditional fiber fine stone concrete that cannot have enough anti-cracking property and durability.

[0037] The high-anti-cracking hybrid fiber concrete for the waterproof protective layer of a railway bridge deck and the application method can effectively improve the service life of the waterproof protective layer of the bridge deck on the basis of ensuring the cost, and form good social, environmental, technical and energy-saving benefits.

[0038] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the following description, or can be learned by practice of the application. The main objects and other advantages of the present application can be achieved and obtained by the solutions specifically pointed out in the description. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0040] Embodiment 1

[0041] A high-anti-cracking C40 hybrid high-alkali-resistant glass fiber concrete for a waterproof protective layer of a railway bridge deck uses the following raw materials:

[0042] One cubic meter of high-anti-cracking C40 hybrid high-alkali-resistant glass fiber concrete contains the following raw materials: P.O42.5 ordinary portland cement 270 kg, II-grade fly ash 90 kg, fine aggregate 684 kg, coarse aggregate 1116 kg, length 12 mm dispersion type high-alkali-resistant glass fiber 0.3 kg, length 36 mm bundled type high-alkali-resistant glass fiber 2.5 kg, water 140 kg, water reducing agent 3.04 kg, and air entraining agent 1.8 kg.

[0043] The following preparation method is used:

[0044] 344 kg / m 3 Medium sand with fineness modulus of 2.4 and 344 kg / m 3 Fine sand with fineness modulus of 1.8 is mixed to prepare fine aggregate, 897 kg / m 3 of 5mm~8mm gravel and 224 kg / m 3 of 8mm~10mm gravel are mixed to prepare coarse aggregate, wherein the gravel with particle size less than 5mm accounts for 6%, and the porosity of coarse aggregate is 36%. Cement, fly ash, fine aggregate, coarse aggregate and length 12mm dispersed high-alkali-resistant glass fiber are put into a mixer to stir for 1min to obtain dry mixture, water, water reducing agent and air entraining agent are added and continue to stir for 2min, then length 36mm bundled high-alkali-resistant glass fiber is put in and continue to stir for 1min, and high-alkali-resistant glass fiber concrete with high crack resistance C40 is prepared after the material is uniformly mixed.

[0045] The high-alkali-resistant glass fiber concrete with high crack resistance C40 prepared by the above scheme has air content of 5.2% out of the machine, concrete slump of 130mm, concrete 28d compressive strength of 48MPa, concrete frost resistance grade of >F400, impermeability grade of ≥P12, electric flux of 861C, 250d shrinkage value of 482με, and crack number per unit area of 6 pieces / m 2 . It shows that the high-alkali-resistant glass fiber concrete with high crack resistance C40 has excellent crack resistance, frost resistance and other durability.

[0046] Example 2

[0047] A high-alkali-resistant polyformaldehyde fiber concrete with high crack resistance C45 for a waterproof protective layer of a railway bridge deck uses the following raw materials:

[0048] A cubic meter of high-alkali-resistant polyformaldehyde fiber concrete with high crack resistance C45 contains P.O42.5 ordinary portland cement 275kg, II-grade fly ash 85kg, fine aggregate 688kg, coarse aggregate 1121kg, length 12mm dispersed polyformaldehyde fiber 0.4kg, length 30mm dispersed polyformaldehyde fiber 1kg, water 136kg, water reducing agent 2.96kg, and air entraining agent 2.0kg.

[0049] The following preparation method is used:

[0050] 344 kg / m 3 Medium sand with fineness modulus of 2.4 and 344 kg / m 3 Fine sand with fineness modulus of 1.8 is mixed to prepare fine aggregate, 897 kg / m 3 of 5mm~8mm gravel and 224 kg / m 38mm~10mm gravel is mixed to prepare coarse aggregate, wherein the gravel with particle size less than 5mm accounts for 5%, and the porosity of the coarse aggregate is 36%. The cement, fly ash, fine aggregate, coarse aggregate and 12mm long dispersed polyformaldehyde fibers are put into a mixer to stir for 1min to obtain dry mixture, water, water reducing agent and air entraining agent are added to continue stirring for 2min, then 30mm long dispersed polyformaldehyde fibers are put in and continue to stir for 1min, and the high-anti-cracking C45 hybrid polyformaldehyde fiber concrete is prepared after the mixture is uniformly mixed.

[0051] The high-anti-cracking C45 hybrid polyformaldehyde fiber concrete prepared by the above scheme has an air content of 6% after being discharged from the machine, a concrete slump of 100mm, a concrete 28d compressive strength of 52MPa, a concrete frost resistance grade of >F400, an impermeability grade of ≥P12, an electric flux of 795C, a 250d shrinkage value of 517με, and a unit area crack number of 8 cracks / m in the anti-cracking plate test 2 , which shows that the high-anti-cracking C45 hybrid polyformaldehyde fiber concrete has excellent anti-cracking performance, frost resistance and other durability.

[0052] Comparative Example 1

[0053] A C40 polyacrylonitrile fiber concrete commonly used as a waterproof protective layer of a railway bridge at present is prepared from the following raw materials:

[0054] One cubic meter of C40 polyacrylonitrile fiber concrete contains the following raw materials: P.O42.5 ordinary portland cement 315kg, II-grade fly ash 135kg, fine aggregate 760kg, coarse aggregate 1050kg, 12mm long polyacrylonitrile fiber 2.5kg, water 160kg, and water reducing agent 5.09kg.

[0055] The following preparation method is used:

[0056] The fine aggregate is II-zone medium coarse sand with a fineness modulus of 2.7, and the coarse aggregate is 5mm~10mm single-grain graded gravel. The cement, fly ash, fine aggregate, coarse aggregate and 10mm long polyacrylonitrile fiber are put into a mixer to stir for 1min to obtain dry mixture, water and water reducing agent are added to continue stirring for 3min, and the C40 polyacrylonitrile fiber concrete is prepared after the mixture is uniformly mixed.

[0057] The C40 polyacrylonitrile fiber concrete prepared by the above scheme has an air content of 2.8% after being discharged from the machine, a concrete slump of 150mm, a concrete 28d compressive strength of 44MPa, a concrete frost resistance grade of >F300, an impermeability grade of ≥P12, an electric flux of 887C, a 250d shrinkage value of 677με, and a unit area crack number of 25 cracks / m in the anti-cracking plate test 2The crack resistance and the frost resistance of the C40 polyacrylonitrile fiber concrete are weaker than those of the high crack resistance C40 hybrid high alkali resistant glass fiber concrete, and it is further proved that the high crack resistance C40 hybrid high alkali resistant glass fiber concrete has good performance.

[0058] Example 3

[0059] Application of a high crack resistance C40 hybrid high alkali resistant glass fiber concrete in construction of a waterproof protective layer of a railway bridge deck.

[0060] From September to October, 2024, in a certain line section of a high-speed railway in the northeast region, on the basis of removing and cleaning the existing waterproof protective layer concrete of the bridge deck, the high crack resistance C40 hybrid high alkali resistant glass fiber concrete of Example 1 of the present application and the C40 polyacrylonitrile fiber concrete commonly used in the present stage in Comparative Example 1 are used to construct the waterproof protective layer between the bridge deck lines. The construction of the C40 polyacrylonitrile fiber concrete based bridge deck waterproof protective layer adopts the traditional construction process, and the specific construction steps of the high crack resistance C40 hybrid high alkali resistant glass fiber concrete based bridge deck waterproof protective layer are as follows:

[0061] (1) The high crack resistance C40 hybrid high alkali resistant glass fiber concrete is prepared on site using a vertical shaft planetary concrete mixer under the bridge, poured into the barrel after preparation, and transported to the bridge deck by a ladder truck, with a mass of 350 kg of high crack resistance hybrid high alkali resistant glass fiber concrete transported each time;

[0062] (2) Four distribution points are set within the length range of a single track slab, and the concrete is uniformly spread by hand and vibrated using a mobile vibrating device, with a walking speed of the mobile vibrating device of 1.2 m / min, and the thickness of the bridge deck waterproof protective layer concrete after vibration is 45 mm;

[0063] (3) A small flat vibrator is used to supplement the vibration of the concrete near the track slab, and a plastic spatula is used to smooth the vibrated concrete, with the surface collected from the middle to both sides, to ensure that the transverse drainage slope is 4% and the longitudinal drainage slope is 3‰, and a transverse joint is set every 4 m along the longitudinal direction;

[0064] (4) Fine finishing: two fine finishing are performed using a steel spatula, with an interval of 5 minutes between the two fine finishing;

[0065] (5) Curing: after the completion of the protective layer construction, the surface is sprayed with 3 times of concrete curing liquid, with a dosage of 400 g / m 2 ;

[0066] (6) On both sides of the transverse joint, the interface agent is coated on the surface of the concrete, the polyethylene foam rod with a circular cross-section and the same diameter as the width of the transverse joint is used to fill the lower part of the transverse joint, and the silicone sealant is filled in the upper part of the transverse joint, and the width-thickness ratio of the sealant is 1.1.

[0067] A bridge deck waterproof layer of C40 polyacrylonitrile fiber concrete and a corresponding traditional construction process has a large number of micro cracks within 1 week after construction, and the number of surface cracks is significantly less when a high-anti-cracking C40 hybrid high-alkali-resistant glass fiber concrete and the construction process of the application are used in the field investigation in June 2025.

[0068] Comparative Example 2

[0069] A C45 polyacrylonitrile fiber concrete commonly used as a railway bridge deck waterproof protective layer at present stage uses the following raw materials:

[0070] One cubic meter of C45 polyacrylonitrile fiber concrete contains the following raw materials: P.O42.5 ordinary portland cement 337 kg, II-grade fly ash 113 kg, fine aggregate 734 kg, coarse aggregate 1056 kg, length 12 mm polyacrylonitrile fiber 2.5 kg, water 156 kg, and water reducing agent 5.17 kg.

[0071] The following preparation method is used:

[0072] The fine aggregate uses II-zone medium-coarse sand with a fineness modulus of 2.7, and the coarse aggregate uses 5 mm-10 mm single-grain graded gravel. The cement, fly ash, fine aggregate, coarse aggregate, and length 10 mm polyacrylonitrile fiber are put into a mixer to stir for 1 min to obtain dry mixture, and water and water reducing agent are continuously stirred for 3 min to obtain C45 polyacrylonitrile fiber concrete after the mixture is uniformly mixed.

[0073] The C45 polyacrylonitrile fiber concrete prepared by the above scheme has an air content of 3.1% out of the machine, a concrete slump of 140 mm, a concrete 28d compressive strength of 50 MPa, a concrete frost resistance grade of >F300, an impermeability grade of ≥P12, an electric flux of 762 C, a 250d shrinkage value of 713 με, and a unit area crack number of 28 cracks / m in the anti-cracking plate test. 2 The anti-cracking performance and the frost resistance of the C45 polyacrylonitrile fiber concrete are both weaker than those of the high-anti-cracking C45 hybrid polyoxymethylene fiber concrete, which further proves that the high-anti-cracking C45 hybrid polyoxymethylene fiber concrete has good performance.

[0074] Comparative Example 3

[0075] By adding different types of fibers with the same amount of mixing into the reference concrete, the influence of the fibers on the working performance of the concrete is compared, wherein the reference C40 concrete uses the following raw materials:

[0076] The raw materials contained in one cubic meter of C40 reference concrete include 420 kg of P.O42.5 low-alkali cement, 706 kg of fine aggregate, 1105 kg of coarse aggregate, 168 kg of water, and 21.2 kg of water reducing agent.

[0077] The fibers are polyacrylonitrile fiber, polypropylene fiber mesh, polypropylene fiber, polyvinyl alcohol fiber, glass fiber and polyformaldehyde fiber respectively, the fiber length is 12 mm, and the fiber content is 0.1% of the mass of the cementitious material. The test results of the influence of different types of fibers on the workability of concrete are as follows:

[0078]

[0079] The comparison results show that using glass fiber or polyformaldehyde fiber can effectively improve the workability of fiber concrete, further proving that the performance of hybrid fiber concrete is good.

[0080] Comparative Example 4

[0081] Economic benefit analysis, the following table is the mix proportion (kg / m 3 ) of polyacrylonitrile fiber concrete and high-anti-cracking hybrid fiber concrete for waterproof protective layer of railway bridge deck.

[0082]

[0083] As can be seen from the table, the example saves about 90 kg of cementitious material compared to the comparative example. According to the current market prices of P.O42.5 low-alkali cement 350 yuan / ton, II-grade fly ash 200 yuan / ton, polyacrylonitrile fiber 13000 yuan / ton, glass fiber 28000 yuan / ton, and polyformaldehyde fiber 30000 yuan / ton, the cost of the mix proportion of the example and the comparative example is equivalent, but the example can significantly reduce the cracking risk and prolong the service life.

[0084] In the concrete construction and transportation link, the example uses a bucket to send a crane with a cost of 30,000 yuan / month, and the comparative example uses a pump truck with a cost of 100,000 yuan / month. The concrete transportation equipment saves 70,000 yuan / month.

[0085] In terms of labor cost, the comparative example construction method requires 5-6 people per working face, and the example construction method requires 8-9 people per working face. According to the labor cost of 200 yuan / person·day, the labor cost is 24,000 yuan more per month.

[0086] In the present specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts are described in the method part.

[0087] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-crack-resistant hybrid fiber-reinforced concrete for waterproof protective layers on railway bridge decks, characterized in that, By weight, each cubic meter of concrete comprises the following components: 260kg~290kg cement, 70kg~100kg fly ash, 679kg~689kg fine aggregate, 1111kg~1121kg coarse aggregate, 135kg~140kg water, and mixed fibers of 2.8kg~3.2kg or 1.2kg~1.6kg depending on the type. Water-reducing agent and air-entraining agent are 0.8%~1.2% and 0.5%~1.5% of the total mass of cement and fly ash, respectively. The hybrid fibers include hybrid high alkali resistant glass fibers or hybrid polyoxymethylene fibers. When hybrid high alkali resistant glass fibers are used, 2.8 kg to 3.2 kg are added per cubic meter of concrete. When hybrid polyoxymethylene fibers are used, 1.2 kg to 1.6 kg are added per cubic meter of concrete. The hybrid high alkali-resistant glass fiber is composed of 10% by weight of 12mm long dispersed high alkali-resistant glass fiber and 90% by weight of 36mm long bundled high alkali-resistant glass fiber; the hybrid polyoxymethylene fiber is composed of 30% by weight of 12mm long dispersed polyoxymethylene fiber and 70% by weight of 30mm long dispersed polyoxymethylene fiber. The fine aggregate is a mixture of medium sand and fine sand in a mass ratio of 1:

1. The coarse aggregate is prepared from 5mm-10mm crushed stone by a combination of shaping and two-stage gradation. The 5mm-10mm crushed stone is sieved into 5mm-8mm and 8mm-10mm particles using an 8mm aperture sieve. The 5mm-8mm and 8mm-10mm crushed stone particles are then blended at a mass ratio of 8:

2. After blending, the porosity of the coarse aggregate is ≤38%. The cement is P.O42.5 ordinary Portland cement with an alkali content ≤0.6%, the fly ash is Class II fly ash, and the total mass of the cement and fly ash in each cubic meter of concrete is ≤360kg; the water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate ≥30%. The air-entraining agent is used to control the air content of the high crack-resistant hybrid fiber concrete to be 4%~6%.

2. The high crack-resistant hybrid fiber concrete for waterproof protective layer of railway bridge deck according to claim 1, characterized in that, The slump of the high crack-resistant hybrid fiber concrete is <140mm; the air content of the high crack-resistant hybrid fiber concrete is controlled to be 4%~6% using the air-entraining agent.

3. A method for preparing high-crack-resistant hybrid fiber concrete for the waterproof protective layer of railway bridge decks as described in claim 2, characterized in that, Includes the following steps: a. Prepare each component according to the required volume of the high crack-resistant hybrid fiber concrete, based on the formula amount; b. Add the cement, fly ash, fine aggregate, and coarse aggregate into a mixer, mix them evenly to obtain a dry mixture, continue mixing and add the water, water-reducing agent, and air-entraining agent; c. When the hybrid high alkali-resistant glass fiber is used, the order of adding the hybrid fiber is as follows: the 12mm long dispersed high alkali-resistant glass fiber is added to the mixer simultaneously with the cement, fly ash, fine aggregate, and coarse aggregate; the 36mm long bundled high alkali-resistant glass fiber is added to the mixer after the water, water-reducing agent, and air-entraining agent are added and mixed for 2 minutes. d. When the hybrid polyoxymethylene fiber is used, the order of adding the hybrid fiber is as follows: the 12mm long dispersed polyoxymethylene fiber is added to the mixer simultaneously with the cement, fly ash, fine aggregate, and coarse aggregate; the 30mm long dispersed polyoxymethylene fiber is added to the mixer after the water, water-reducing agent, and air-entraining agent are added and mixed for 2 minutes. e. After the components are mixed evenly, the high crack-resistant hybrid fiber concrete for the waterproof protective layer of the railway bridge deck is prepared.

4. The method for preparing high crack-resistant hybrid fiber concrete for waterproof protective layer of railway bridge deck according to claim 3, characterized in that, The total stirring time is started from the time the water, water-reducing agent and air-entraining agent are added, and the total stirring time is ≤3min.

5. The method for preparing high crack-resistant hybrid fiber concrete for waterproof protective layer of railway bridge deck according to claim 3, characterized in that, The mixer is a vertical shaft planetary concrete mixer or a forced single-shaft concrete mixer.

6. The application of the high crack-resistant hybrid fiber concrete for railway bridge deck waterproofing protective layer as described in claim 2, or the high crack-resistant hybrid fiber concrete for railway bridge deck waterproofing protective layer prepared by the preparation method described in any one of claims 3-5, in the construction of railway bridge deck waterproofing protective layer.

7. The application of the high crack-resistant hybrid fiber concrete for railway bridge deck waterproofing protective layer according to claim 6 in the construction of railway bridge deck waterproofing protective layer, characterized in that, Includes the following steps: (1) Fabrication: Prepare high crack-resistant hybrid fiber concrete for the waterproof protective layer of railway bridge deck on site and transport it to the fabrication point on the bridge deck. The number of fabrication points within the length of a single track slab is >2. (2) Spreading and compacting: Spread the concrete evenly, use a mobile vibrating device to compact the concrete, and then use a small flat vibrator to compact the concrete near the track slab. (3) Rough finishing: Use a plastic trowel to smooth and polish the vibrated concrete, finishing from the middle to both sides, ensuring that the transverse drainage slope is ≥4% and the longitudinal water collection slope is ≥3‰, and a transverse break joint is set every 4m along the longitudinal direction. (4) Fine finishing: Use a steel trowel to perform two fine finishing processes on the concrete after rough finishing, with a 5-minute interval between the two fine finishing processes; (5) Curing: 30 minutes after the completion of the protective concrete construction, spray concrete curing liquid onto its surface, spraying more than 2 times, with each application using 400g / m² of concrete curing liquid. 2 ; (6) Sealing: Silicone sealant is used to seal the transverse joint.

8. The application of the high crack-resistant hybrid fiber concrete for railway bridge deck waterproofing protective layer according to claim 7 in the construction of railway bridge deck waterproofing protective layer, characterized in that, In step (1), the temperature of the high crack-resistant hybrid fiber concrete used for the waterproof protective layer of the railway bridge deck is ≥5℃ when it is transferred to the bridge deck placement point. Step (2) The walking speed of the mobile vibrating equipment is <1.5m / min; the thickness of the protective concrete layer after paving and vibration is ≥40mm. If the paving thickness is insufficient, add material to the surface and drive the mobile vibrating equipment back for secondary vibration.

9. The application of the high crack-resistant hybrid fiber concrete for railway bridge deck waterproofing protective layer according to claim 7 in the construction of railway bridge deck waterproofing protective layer, characterized in that, The specific method for sealing the transverse fracture with silicone sealant in step (6) is as follows: apply an interface agent to the concrete surface on both sides of the transverse fracture, use a polyethylene foam rod with a circular cross section and the same diameter as the width of the transverse fracture as a support material to fill the lower part of the transverse fracture, fill the upper part of the polyethylene foam rod with silicone sealant, and ensure that the width-to-thickness ratio of the silicone sealant is >1.

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