Railway track structure concrete super-early-strength repairing mortar as well as preparation method and application thereof

Abstract

The invention discloses super-early-strength repair mortar for railway track structure concrete as well as a preparation method and application of the super-early-strength repair mortar. The super-early-strength repair mortar is prepared by mixing Portland cement, sulphoaluminate cement, a mineral admixture, quartz sand, fibers, a resin emulsion, a curing agent, an early strength agent, a rheological additive, a water reducing agent and water. The building material is prepared from the following components in parts by mass: 20 to 40 parts of superfine Portland cement, 60 to 80 parts of sulphoaluminate cement, 5 to 10 parts of mineral admixture, 160 to 200 parts of quartz sand, 1 to 3 parts of fiber, 2 to 6 parts of resin emulsion, 1 to 3 parts of curing agent, 1 to 5 parts of early strength agent, 0.001 to 0.005 part of rheological additive, 0.01 to 0.03 part of defoaming agent, 3 to 5 parts of water reducing agent and 15 to 30 parts of water. The construction method comprises the following steps: chiseling and dedusting a crack area; drilling and planting steel bars; mounting and pouring a mold; and removing the mold. The mortar provided by the invention has the advantages of self-leveling, high early strength, high fracture resistance, low shrinkage, corrosion resistance and the like, has high interface bonding strength after repairing, can be used for quickly repairing concrete damaged parts of a railway track structure, and can also be used for pavement projects of roads, airports and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a super-early-strength repair mortar for railway track structure concrete, a preparation method thereof and an application thereof. Background Art

[0002] Under the long-term reciprocating and frequent braking loads of high-speed train loads, various diseases or damages (such as cracks, separation joints, peeling and chipping, etc.) will occur in the track structure concrete, seriously affecting the stability, smoothness and durability of the track structure. In order to effectively repair structural cracks and extend the service life of the structure, it is of great significance to develop high-performance repair materials.

[0003] The track structure concrete bears the repeated forced braking loads from high-speed trains, and requires the repair material to have a high bond strength with the interface of the old concrete. By adding polymers, the interface bond strength can be improved, but after operating for a period of time, it is found that cracks occur at the interface between the repair material and the old concrete, that is, the shear strength of the interface zone is insufficient.

[0004] In addition, during railway operation, the "skylight time" for maintenance is very short. Without affecting railway operation, the compressive strength of the repair material is required to reach more than 20 MPa in 2 hours, and higher requirements are required under special conditions to meet the requirements of opening to traffic. The early compressive strength of the portland cement repair material is low and does not meet the strength requirements, and the shrinkage is large. The early strength of the sulfoaluminate cement repair material is high, but the brittleness is large and it cannot resist the impact fatigue loads of high-speed trains. Chinese Patent CN111533517A reports a rapid repair mortar for high-speed railway concrete track slabs, which uses a compound of sulfoaluminate cement, portland cement or ultra-fine cement. The 2-hour compressive strength of the rapid repair mortar reaches more than 21 MPa, the 1-day compressive strength is more than 42 MPa, and the 28-day compressive strength can reach 70 MPa; the flexural strength of the mortar can reach more than 4.3 MPa, more than 6.3 MPa and more than 11.7 MPa at 2 hours, 1 day and 28 days respectively. However, the flexural strength of the repair mortar reported in this patent is relatively low and cannot meet the high-strength and high-frequency impact loads of future ultra-high-speed railways, subways and other trains.

[0005] In summary, the repair materials for railway track concrete structures need to have the characteristics of low viscosity, super-early strength, high interface bond strength, fatigue resistance, etc. However, the existing repair materials and methods are difficult to meet the above requirements. With the rapid development of China's railway transportation, the maintenance and transformation of existing lines have become one of the core issues of railway transportation. Therefore, this material has a huge market prospect. Summary of the Invention

[0006] Based on the above technical problems existing in the prior art, the present invention provides a railway track structure concrete ultra-early strength repair mortar and its preparation method and application. Through multi-component cementitious material composite technology, polymer emulsion modification technology, nano-material seed early strength technology, hybrid fiber toughening technology, and implanted shear reinforcement technology, the early strength, toughness and interface shear resistance of the repair material are improved.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A super-early-strength repair mortar for railway track structure concrete, whose raw material components include, by weight: 20-40 parts of superfine silicate cement, 60-80 parts of sulphoaluminate cement, 5-10 parts of mineral admixture, 160-200 parts of quartz sand, 1-3 parts of fiber, 2-6 parts of resin emulsion, 1-3 parts of curing agent, 1-5 parts of early strength agent, 0.001-0.005 parts of rheological additive, 0.01-0.03 parts of defoaming agent, 3-5 parts of water reducer and 15-30 parts of water.

[0009] In the present invention, the above-mentioned repair mortar can also be composed of the above-mentioned raw materials.

[0010] Furthermore, the cement is a mixture of ultrafine silicate cement and sulphoaluminate cement.

[0011] Furthermore, the resin emulsion is a water-based epoxy resin or polyacrylic resin emulsion.

[0012] Furthermore, the sand is graded quartz sand with a particle size of less than 2.36 mm.

[0013] Furthermore, the mineral admixture is one or two of silica fume, S95 grade mineral powder, and fly ash.

[0014] Furthermore, the fibers are steel fibers and basalt fibers.

[0015] Furthermore, the curing agent is one or two of a polyamine curing agent, a modified fatty amine curing agent, and a phenolic amine curing agent.

[0016] Furthermore, the defoaming agent is a silicone defoaming agent.

[0017] Furthermore, the water reducing agent is a polycarboxylic acid high efficiency water reducing agent, and the water reducing rate is greater than 25%.

[0018] Furthermore, the early strength agent is one or two of nano CSH seed crystals, nano silicon dioxide, and triethanolamine.

[0019] Furthermore, the water is city tap water.

[0020] Further, the rheology modifier is redispersible latex powder or hydroxymethyl cellulose ether.

[0021] A preparation method of a super-early-strength repair mortar for railway track structure concrete, comprising the following steps:

[0022] First, mix the resin emulsion, curing agent, defoamer, water reducer and water for 60 s and set aside; then add cement, mineral admixture, quartz sand, fiber, early-strength agent and rheology modifier into the mixture and stir evenly to obtain the repair mortar.

[0023] Application of the above-mentioned super-early-strength repair mortar for railway track structure concrete in the repair of railway track structure concrete.

[0024] Further, the application comprises the following steps: chiseling and dust removal of the repair area, drilling and rebar planting, formwork installation, pouring, and formwork removal.

[0025] Further, the rebar used for rebar planting is steel bar or basalt fiber bar.

[0026] The present invention utilizes the ettringite generated by the rapid hydration of sulfoaluminate cement and the high heat of hydration to improve the early strength of Portland cement and reduce the setting and hardening time. The secondary hydration of mineral admixtures ensures the stable growth of the later strength. The resin emulsion reduces the viscosity of the polymer through emulsification technology, improves its compatibility with the cement system, and is conducive to improving the fluidity of the composite cementitious system. After the polymer is cured, the polar functional groups on the macromolecular chain enhance the interfacial bonding strength. Utilizing the nucleation effect of nano C-S-H seeds and nano-silica, the hydration rate of the cementitious system is accelerated, and at the same time, the nano-materials play a role of particle filling, further improving the early strength of the cementitious system. Utilizing the hybrid synergistic toughening principle of steel fiber and chopped fiber to improve the toughness of the repair material. Due to the high elastic modulus and weak deformation ability of steel fiber, it can play a role of micro-reinforcement. The chopped fiber has strong deformation ability, relieves the concentrated stress of cracks, inhibits crack generation, and thus resists the high-strength impact load of high-speed trains. The use of rebar planting improves the shear bearing capacity of the interface between the repair material and the old concrete. In a corrosive environment, high-corrosion-resistant basalt fiber bars are selected to further improve the ability of the interface between the new and old concrete to resist impact loads.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The present invention realizes the advantages of self-leveling, high early strength, high flexural strength, low shrinkage, corrosion resistance, etc. of the repair material through multi-component cementitious material composite technology, polymer emulsion modification technology, nano-material seed early strength technology, hybrid fiber toughening technology, and rebar planting shear technology. The interface after repair can resist the strong shear action of the impact load of high-speed trains. The technical and economic effects of the present invention are remarkable, and it can provide material and technical support for the maintenance of infrastructure such as bridges, roads, airports, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 The following are the comparison photos before and after repairing the ballastless track sleeper using the ultra-early-strength repair mortar for railway track structure concrete of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In order to facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in combination with the accompanying drawings of the specification and the preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0032] Unless otherwise defined, all the professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0033] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in the present invention can be obtained through the market or prepared by existing methods.

[0034] The specific construction steps of the embodiments of the present invention are as follows: ① Use a hand-held impact drill to chisel off the concrete in the damaged area of the track structure, and clean the concrete debris in the repair area with a hair dryer; ② Drill holes in the repair area with an electric drill, with a drilling depth of about 2 cm, and implant the prepared steel bars or basalt fiber bars into the corresponding holes; ③ Assemble the steel plate mold according to specific dimensions, fix the four sides of the mold with foaming materials, and pour the repair material prepared according to the ratio of the embodiment into the mold (for areas where no steel bar implantation or formwork support is required, the repair material can be directly applied and the surface can be polished after hardening); ④ Remove the mold 0.5 hours after the repair material hardens. The comparison diagram of the track structure before and after repair is as Figure 1 shown.

[0035] The ultra-early-strength repair mortar for railway track structure concrete provided by the present invention, calculated by mass parts, the raw material components thereof include: 20-40 parts of ultra-fine Portland cement, 60-80 parts of sulfoaluminate cement, 5-10 parts of mineral admixture, 160-200 parts of quartz sand, 1-3 parts of fiber, 2-6 parts of resin emulsion, 1-3 parts of curing agent, 1-5 parts of early-strength agent, 0.001-0.005 parts of rheology aid, 0.01-0.03 parts of defoaming agent, 3-5 parts of water-reducing agent, and 15-30 parts of water.

[0036] The present invention has designed a total of 4 groups of examples and 6 groups of comparative examples, as shown in Table 1 specifically. The preparation method is as follows:

[0037] First, mix the resin emulsion, curing agent, defoamer, water reducing agent and water for 60 s and set aside; then add cement, mineral admixture, quartz sand, fiber, early strength agent and rheology aid to the mixed solution and stir evenly to obtain the repair material.

[0038] The physical and mechanical properties of the repair material are tested according to the relevant regulations of the "Rules for Maintenance of High-Speed Railway Lines" (TG / GW 115-2023), and the test results are shown in Table 2.

[0039] Table 1 Mix ratio of ultra-early-strength repair mortar

[0040]

[0041]

[0042] Table 2 Test results of the properties of ultra-early-strength repair mortar

[0043]

[0044] Compared with Example 1, Comparative Example 1 only uses ultrafine portland cement, and it can be seen that its compressive strength and flexural strength are significantly reduced. Compared with Example 2, Comparative Example 2 only uses sulfoaluminate cement, and it can be seen that its 2h compressive strength and flexural strength are lower, and the spread is low, without self-leveling effect. Compared with Example 1, Comparative Example 3 does not use nano-seed early strength agent, and it can be seen that its 0.5h compressive strength is significantly reduced. Compared with Example 1, Comparative Example 4 does not use composite mineral admixture, and it can be seen that its compressive strength is lower. Compared with Example 3, Comparative Example 5 only uses 2 parts of steel fiber, and it can be seen that its flexural strength is lower. Compared with Example 4, Comparative Example 6 only uses 2 parts of basalt fiber, and it can be seen that its flexural strength is reduced.

[0045] From the performance data of the ultra-early-strength repair materials provided in each example in Table 2, it can be known that the ultra-early-strength repair material of the present invention has the advantages of self-leveling, high early strength, high flexural strength, low shrinkage, corrosion resistance, etc. After repair, the interfacial bonding strength is high, and it can be used for rapid repair of concrete cracks and damages in railway track structures, and can also be used for pavement projects such as highways and airports.

[0046] The above-mentioned examples only represent two cases of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A concrete ultra-early-strength repair mortar for railway track structures, characterized in that, By weight, its component contents include: 20-40 parts of ultrafine portland cement, 60-80 parts of sulfoaluminate cement, 5-10 parts of mineral admixture, 160-200 parts of quartz sand, 1-3 parts of fiber, 2-6 parts of resin emulsion, 1-3 parts of curing agent, 1-5 parts of early strength agent, 0.001-0.005 parts of rheology aid, 0.01-0.03 parts of defoamer, 3-5 parts of water reducer, and 15-30 parts of water.

2. The curing agent according to claim 1 is one or two of polyamine curing agent, modified aliphatic amine curing agent, and phenolic amine curing agent; the defoamer is an organosilicon defoamer; the water reducer is a polycarboxylate water reducer.

3. The ultra-early-strength repair mortar for railway track structure concrete according to claim 1, characterized in that, The resin emulsion is an aqueous epoxy resin emulsion.

4. The ultra-early-strength repair mortar for railway track structure concrete according to claim 1, characterized in that, The mineral admixture is one or two of silica fume, S95 grade blast furnace slag powder, and fly ash.

5. The ultra-early-strength repair mortar for railway track structure according to claim 1, characterized in that, The fiber is steel fiber and basalt fiber.

6. The ultra-early-strength repair mortar for railway track structure concrete according to claim 1, characterized in that, The early strength agent is one or two of nano C-S-H seeds, nano silica, and triethanolamine; the rheology aid is redispersible latex powder or hydroxyethyl methyl cellulose ether.

7. The preparation method of the ultra-early-strength repair mortar for railway track structure concrete according to any one of claims 1-6, characterized in that, It includes the following steps: First, mix the resin emulsion, curing agent, defoamer, water reducer, and water for 60 s and set aside; then mix the cement, mineral admixture, quartz sand, fiber, early strength agent, and rheology aid in a mixed solution and stir evenly to obtain the repair mortar.

8. Application of the super early strength repair mortar for railway track structure concrete according to any one of claims 1-6 in the repair of railway track structure concrete.

9. The application according to claim 8, wherein It includes the following steps: Chisel and dust the area to be repaired, drill and insert reinforcement, install the formwork, pour, and remove the formwork.

10. The application according to claim 8, wherein The inserted reinforcement is selected from steel bars or basalt fiber bars.

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