Composition for mortar, mortar as well as preparation method and application of mortar

Abstract

The invention relates to the technical field of high-speed railway repair materials, and discloses a composition for mortar, the mortar and a preparation method and application of the mortar. The composition contains a main agent and an auxiliary agent, the main agent contains a basic component, a fine aggregate, a first component, a second component and a styrene-butadiene emulsion; the basic component is prepared from 70 wt% to 80 wt% of sulphoaluminate cement, 15 wt% to 25 wt% of Portland cement and 2.5 wt% to 7.5 wt% of dihydrate gypsum; the first component contains calcium oxide, sodium silicate and single-component waterborne polyurethane; the second component contains aluminum sulfate, a layered dihydroxide, sodium formate and nano silicon dioxide. The mortar obtained by adopting the composition for the mortar provided by the invention has a good application prospect in the repair of ballastless tracks of high-speed railways in a negative temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of high-speed railway repair materials, and particularly relates to a composition for mortar, mortar, a preparation method thereof, and an application thereof. Background Art

[0002] In China, more than 5,000 kilometers of high-speed railway lines use CA mortar (cement emulsified asphalt mortar) as the filling layer material of the CRTS II-type slab ballastless track structure, and most of these lines are main lines that have been in service for more than ten years.

[0003] After more than ten years of service, some diseases such as interlayer separation joints and vertical cracks appear in the filling layer of high-speed railway lines, and the above diseases need to be repaired in time to ensure the smooth operation of high-speed railways; at the same time, the settlement of some lines is much larger than the elevation adjustment range of railway fasteners, and it is urgent to uncover the track slab and chisel out the original filling layer material and then lay a new filling layer material to adjust the track elevation to ensure the smoothness of the track structure.

[0004] In addition, there are diseases such as defects at the corners of the base and block dropping at the exhaust ports at the four corners of the self-compacting concrete filling layer in some high-speed railway tracks, which affect the structural stress of the ballastless track and endanger the operation safety of trains, and urgent repairs are needed.

[0005] In Northeast China, North China, Northwest China and other places in China, the average temperature is lower than -5°C for 3 to 6 months every year, and high-speed railway Beijing-Harbin to Hong Kong channels, Beijing-Shanghai channels, Lanxi channels, etc. all pass through the above-mentioned "Three-North Regions". This poses a huge challenge to the repair of the ballastless track filling layer and slab replacement in winter, which requires the repair material to form a relatively high strength within 4 hours of the skylight repair period under negative temperature conditions to meet the high-speed railway operation conditions.

[0006] The "Maintenance Rules for Ballasted High-Speed Railway Lines" (Railway Transportation

[2012] No. 83) and "Repair Mortar for High-Speed Railway Concrete Structures" (Q / CR 659-2018) stipulate that polymer cement mortar should be used to repair the diseases of the ballastless track filling layer or concrete defects.

[0007] However, high molecular polymers usually delay the hydration of cement, resulting in slow early strength development; and cement also faces challenges such as slow strength development, serious early frost damage, and serious bleeding at low temperatures, resulting in the inability of cement-based materials to be used in repair operations under negative temperature conditions in winter.

[0008] Therefore, there is an urgent need for a polymer mortar composition that can be used in a negative temperature environment and can complete the repair of the ballastless track structure of high-speed railways within the skylight period for use in ballastless track repair operations under low temperature conditions in winter to ensure the operation safety of the line. Summary of the Invention

[0009] The object of the present invention is to provide a polymer mortar material for repairing the ballastless track structure of high-speed railways in a negative temperature environment and capable of completing the repair within the skylight period.

[0010] To achieve the above object, a first aspect of the present invention provides a composition for mortar, which composition contains a main agent and an auxiliary agent; the main agent contains a basic component, fine aggregate, a first component, a second component and styrene-butadiene emulsion;

[0011] The basic component contains 70wt%-80wt% of sulfoaluminate cement, 15wt%-25wt% of portland cement and 2.5wt%-7.5wt% of dihydrate gypsum;

[0012] Relative to 100 parts by weight of the basic component, the content of the fine aggregate is 80-120 parts by weight, the content of the first component is 4-13 parts by weight, the content of the second component is 1-4 parts by weight, and the content of the styrene-butadiene emulsion is 6-10 parts by weight;

[0013] The first component is calcium oxide, sodium silicate and one-component waterborne polyurethane with a mass ratio of 3-5:1-2:2-3;

[0014] The second component is aluminum sulfate, layered double hydroxide, sodium formate and nano-silica with a mass ratio of 0.5-1.5:0.5-1.5:0.1-0.2:0.1-0.3;

[0015] The viscosity of the styrene-butadiene emulsion at 23°C is 1000-1200 mPa·s.

[0016] A second aspect of the present invention provides a method for preparing mortar, which method is carried out using the components in the composition described in the first aspect above, and includes:

[0017] Mixing and contacting the components in the main agent and the components in the auxiliary agent to obtain mortar.

[0018] A third aspect of the present invention provides the mortar prepared by the method described in the second aspect above.

[0019] A fourth aspect of the present invention provides the application of the mortar described in the third aspect above in repairing the ballastless track of high-speed railways in a negative temperature environment.

[0020] The mortar obtained by using the composition for mortar provided by the present invention can complete the repair of the ballastless track structure of high-speed railways within the skylight period in a negative temperature and low temperature environment, overcoming the problems of slow strength development, irreversible frost damage, serious bleeding, etc. of polymer cement mortar under winter negative temperature and low temperature conditions.

[0021] The method for preparing mortar provided by the present invention is simple and easy to scale up production. Detailed implementation manners

[0022] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] It should be noted that in the present invention, the modulus refers to the ratio of the molar amount of silicon dioxide to the molar amount of sodium oxide in sodium silicate.

[0024] As described above, the first aspect of the present invention provides a composition for mortar, which composition contains a main agent and an auxiliary agent; the main agent contains a basic component, fine aggregate, a first component, a second component and a styrene-butadiene emulsion;

[0025] The basic component contains 70wt%-80wt% of sulfoaluminate cement, 15wt%-25wt% of portland cement and 2.5wt%-7.5wt% of gypsum dihydrate;

[0026] Relative to 100 parts by weight of the basic component, the content of the fine aggregate is 80-120 parts by weight, the content of the first component is 4-13 parts by weight, the content of the second component is 1-4 parts by weight, and the content of the styrene-butadiene emulsion is 6-10 parts by weight;

[0027] The first component is calcium oxide, sodium silicate and one-component aqueous polyurethane with a mass ratio of 3-5:1-2:2-3;

[0028] The second component is aluminum sulfate, layered double hydroxide, sodium formate and nano-silicon dioxide with a mass ratio of 0.5-1.5:0.5-1.5:0.1-0.2:0.1-0.3;

[0029] The viscosity of the styrene-butadiene emulsion at 23°C is 1000-1200 mPa·s.

[0030] Preferably, the pH value of the one-component aqueous polyurethane is 6-9, and the viscosity at 23°C is 50-800 mPa·s. The inventors of the present invention have found that in this preferred case, the obtained mortar has more excellent compressive strength.

[0031] Preferably, the modulus of the sodium silicate is 2.5-3.1.

[0032] Preferably, the layered double hydroxide is calcium-aluminum layered double hydroxide.

[0033] Preferably, the auxiliary agent contains a water reducing agent, an antifoaming agent and water;

[0034] Relative to 100 parts by weight of the base component, the content of the water reducing agent is 0.2 - 1 part by weight, the content of the antifoaming agent is 0.02 - 0.05 part by weight, and the content of water is 15 - 27 parts by weight.

[0035] The present invention has no special requirements for the type of water, and those skilled in the art can select according to needs. Exemplarily, the water is tap water.

[0036] Preferably, the fine aggregate is quartz sand.

[0037] More preferably, the fine aggregate is quartz sand with a particle diameter between 0.21 mm and 1.68 mm.

[0038] As described above, the second aspect of the present invention provides a method for preparing mortar, which is carried out using the components in the composition described in the first aspect above, including:

[0039] Mixing and contacting the components in the main agent and the components in the auxiliary agent to obtain mortar.

[0040] According to a preferred specific embodiment, the step of mixing and contacting the components in the main agent and the components in the auxiliary agent includes:

[0041] (1) First, stir and mix the base component, the powdered calcium oxide in the first component, and the powdered sodium silicate in the first component to obtain a powder material;

[0042] And second, stir and mix the second component and the auxiliary agent to obtain a liquid material;

[0043] (2) Contact and mix the powder material, the liquid material, the styrene-butadiene emulsion, and the fine aggregate to obtain mixture I;

[0044] (3) Contact and mix mixture I with the one-component aqueous polyurethane in the first component to obtain mortar.

[0045] According to another preferred specific embodiment, the method further includes: before step (2), storing the fine aggregate, the powder material obtained in step (1), and the liquid material at -8°C to -3°C for 18 - 30 h and then applying them to simulate a negative temperature application environment.

[0046] Preferably, in step (2), the contact mixing I includes: first stirring the powder material and the liquid material for 1 - 1.5 min, then adding the styrene-butadiene emulsion and continuing to stir for 1 - 1.5 min, and finally adding the fine aggregate and stirring for 1 - 1.5 min to obtain mixture I.

[0047] Preferably, in step (3), the conditions of contact mixing II include: temperature of 0-20° C., rotation speed of 140-285 rpm, and time of 1-3 min.

[0048] As mentioned above, the third aspect of the present invention provides mortar prepared by the method described in the second aspect.

[0049] As mentioned above, the fourth aspect of the present invention provides the use of the mortar described in the third aspect in the repair of high-speed railway ballastless track in a negative temperature environment.

[0050] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the instruments, reagents, materials, etc. involved are all conventional instruments, reagents, materials, etc., which can be obtained through regular commercial channels. Among them, unless otherwise specified, the reagents used are all commercially available analytically pure products.

[0051] Sulphoaluminate cement: 425 low alkalinity sulphoaluminate cement, purchased from Yudengdian Group Cement Co., Ltd., brand 425.

[0052] Portland cement: 425 Portland standard cement, purchased from China Building Materials Research Institute.

[0053] Fine aggregate: quartz sand, with an average particle diameter of 0.97 mm, purchased from Hunan Juke Technology Co., Ltd.

[0054] Styrene butadiene emulsion:

[0055] Styrene butadiene emulsion I: Styrene butadiene emulsion, with a viscosity of 1125 mPa·s at 23° C., was purchased from Shenzhen Jitian Chemical Co., Ltd. with a brand number of 106#.

[0056] Styrene butadiene emulsion DI: Styrene butadiene emulsion, with a viscosity of 243 mPa·s at 23° C., was purchased from BASF (China) Co., Ltd. with a brand name of ECO 7623.

[0057] One-component waterborne polyurethane:

[0058] One-component waterborne polyurethane I: waterborne polyurethane dispersion, pH value of 8, viscosity of 320 mPa·s at 23° C., purchased from Guangzhou Haoyi New Materials Co., Ltd., brand U58.

[0059] One-component waterborne polyurethane II: waterborne polyurethane grouting liquid, pH value of 7, viscosity of 845 mPa·s at 23° C., purchased from Guangzhou Kedun Waterproof Materials Co., Ltd., brand KD-669.

[0060] Sodium silicate: powder, modulus 3.1, purchased from Shanghai McLean Biochemical Technology Co., Ltd.

[0061] Layered double hydroxide: Calcium-aluminum layered double hydroxide, purchased from Angxing New Carbon Materials Changzhou Co., Ltd., with the product number ECS006144.

[0062] Water reducing agent: Polycarboxylate water reducing agent, purchased from Xinyi Synthesis Co., Ltd., with the model number CP1903.

[0063] Defoaming agent: Defoaming agent, purchased from Zhaojia Technology Co., Ltd., with the model number ZJ-D130.

[0064] In the following examples, unless otherwise specified, all amounts are represented by weight parts, and each weight part = 100 g.

[0065] Example 1

[0066] This example is used to illustrate the mortar composition shown in Table 1 and prepare mortar according to the following steps:

[0067] (1) First, stir and mix the base components, calcium oxide in the first component, and sodium silicate in the first component to obtain a powder;

[0068] And second, stir and mix the second component and the additives (water reducing agent, defoaming agent, and tap water. Each component in the additives is used after being placed in an environment of 0 °C for 24 hours) to obtain a liquid material;

[0069] (2) Stir the powder and the liquid material for 1 min, then add styrene-butadiene latex and continue to stir for 1 min, and finally add fine aggregate and stir for 1 min to obtain Mixture I;

[0070] The powder, liquid material, and fine aggregate in step (2) are all stored at -5 °C for 24 h in advance before use;

[0071] (3) Contact and mix Mixture I with the one-component waterborne polyurethane in the first component to obtain mortar;

[0072] Contact mixing II: The temperature is 20 °C, the rotation speed is 285 rpm, and the time is 1 min.

[0073] Without special instructions, Examples 2 - 4 and Comparative Example 1 are carried out in a similar manner to Example 1, and the difference lies in the raw material formula, as specifically shown in Table 1.

[0074] Example 5

[0075] This example is carried out in a similar method to Example 1, and the difference is that: this example uses an equal weight part of one-component waterborne polyurethane II to replace one-component waterborne polyurethane I in Example 1 to prepare mortar, and the rest is the same as Example 1 to prepare mortar.

[0076] Comparative Example 2

[0077] This comparative example was carried out in a similar manner to Example 1, except that: in this comparative example, styrene-butadiene emulsion DI in equal weight parts was used to replace styrene-butadiene emulsion I in Example 1 to prepare mortar, and the rest was the same as in Example 1 to prepare mortar.

[0078] Comparative Example 3

[0079] 100 parts by weight of the base components (the mass ratio of sulfoaluminate cement, portland cement and gypsum dihydrate is 75:20:5), 100 parts by weight of fine aggregate, 5 parts by weight of styrene-butadiene emulsion I, 0.6 parts by weight of water reducing agent, 0.04 parts by weight of defoaming agent and 26.5 parts by weight of tap water (the water reducing agent, defoaming agent and tap water were all used after being placed in an environment of 0 °C for 24 hours) were stirred and mixed to obtain mortar.

[0080] Comparative Example 4

[0081] (1) The base components, calcium oxide in the first component and sodium silicate in the first component were subjected to a first stirring and mixing to obtain a powder.

[0082] (2) The powder was stirred with the additives (water reducing agent, defoaming agent and tap water, and each component in the additives was used after being placed in an environment of 0 °C for 24 hours) for 1 min, then styrene-butadiene emulsion was added and stirred for another 1 min, and finally fine aggregate was added and stirred for 1 min to obtain mixture I.

[0083] The powder and fine aggregate in step (2) were both stored at -5 °C for 24 h in advance and then used.

[0084] (3) The mixture I was subjected to a contact mixing II with the one-component waterborne polyurethane in the first component to obtain mortar.

[0085] The parts not listed were the same as in Example 1.

[0086] Comparative Example 5

[0087] (1) The second component and the additives (water reducing agent, defoaming agent and tap water, where the tap water is 26.5 parts by weight, and each component in the additives was used after being placed in an environment of 0 °C for 24 hours) were subjected to a second stirring and mixing to obtain a liquid material.

[0088] (2) The base components and the liquid material were stirred for 1 min, then styrene-butadiene emulsion was added and stirred for another 1 min, and finally fine aggregate was added and stirred for 1 min to obtain mortar.

[0089] The base components, liquid material and fine aggregate in step (2) were all stored at -5 °C for 24 h in advance and then used.

[0090] For the unenumerated parts, they are the same as those in Example 1.

[0091] Comparative Example 6

[0092] This comparative example was carried out by a method similar to that of Example 1. The difference is that, on the basis of keeping the dosage of the first component unchanged, the mass ratio of calcium oxide, sodium silicate and single-component aqueous polyurethane in the first component was adjusted to 2:4:4 to obtain the mortar. For the unenumerated parts, they are the same as those in Example 1.

[0093] Comparative Example 7

[0094] This comparative example was carried out by a method similar to that of Example 1. The difference is that, on the basis of keeping the dosage of the second component unchanged, the mass ratio of aluminum sulfate, layered double hydroxide, sodium formate and nano-silica in the second component was adjusted to 0.1:0.1:0.3:0.5 to obtain the mortar. For the unenumerated parts, they are the same as those in Example 1.

[0095] Table 1

[0096]

[0097] Test Example

[0098] The properties of the mortar obtained in the above examples were tested by using the cement mortar strength test method in GB / 17671, the cement mortar dry shrinkage test method in JC / T 603, and the basic performance test method of building mortar in JGJ / T 70. The results are shown in Table 2 and Table 3:

[0099] Among them, the 7-day expansion rate = (the length of the sample to be tested on the 7th day - the initial length of the sample to be tested) / the initial length of the sample to be tested × 100%.

[0100] Table 2

[0101]

[0102] Note: In the 7-day expansion rate, “﹢” indicates volume expansion, and “-” indicates volume contraction.

[0103] Table 3

[0104] Flexural strength after 2 h / (MPa) Flexural strength after 1 day / (MPa) Flexural strength after 7 days / (MPa) Example 1 6.6 9 10.8 Example 2 5.4 7.8 9.7 Example 3 4.7 7.5 9.3 Example 4 7.2 8.9 10.4 Example 5 5.1 7.1 9.0 Comparative Example 1 1.0 2.4 6.2 Comparative Example 2 1.9 3.9 6 Comparative Example 3 0.1 1.3 4.5 Comparative Example 4 1.7 4 6.1 Comparative Example 5 2.6 5.1 7.4 Comparative Example 6 3.5 6.3 8.1 Comparative Example 7 2.4 4.9 7.0

[0105] From the above results, it can be seen that the mortar prepared by using the mortar composition provided by the present invention still has excellent compressive strength and flexural strength under the environment of simulating negative temperature, overcoming the problems such as slow strength development, irreversible freeze damage, and serious bleeding of polymer cement mortar under winter negative temperature and low temperature conditions.

[0106] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A mortar composition, characterized in that: The composition comprises a main agent and an auxiliary agent; the main agent comprises a base component, fine aggregate, a first component, a second component and styrene-butadiene emulsion; The basic component contains 70wt%-80wt% of sulphoaluminate cement, 15wt%-25wt% of silicate cement and 2.5wt%-7.5wt% of dihydrate gypsum; Relative to 100 parts by weight of the base component, the content of the fine aggregate is 80-120 parts by weight, the content of the first component is 4-13 parts by weight, the content of the second component is 1-4 parts by weight, and the content of the styrene-butadiene emulsion is 6-10 parts by weight; The first component is calcium oxide, sodium silicate and single-component waterborne polyurethane in a mass ratio of 3-5:1-2:2-3; The second component is aluminum sulfate, layered double hydroxide, sodium formate and nano silicon dioxide in a mass ratio of 0.5-1.5:0.5-1.5:0.1-0.2:0.1-0.3; The viscosity of the styrene-butadiene emulsion at 23° C. is 1000-1200 mPa·s.

2. The composition according to claim 1, characterized in that The pH value of the one-component waterborne polyurethane is 6-9, and the viscosity at 23° C. is 50-800 mPa·s.

3. The composition according to claim 1 or 2, characterized in that The modulus of the sodium silicate is 2.5-3.1; And / or, the layered double hydroxide is a calcium aluminum layered double hydroxide.

4. The composition according to any one of claims 1 to 3, characterized in that The auxiliary agent contains a water reducing agent, a defoaming agent and water; Relative to 100 parts by weight of the base component, the content of the water reducing agent is 0.2-1 parts by weight, the content of the defoaming agent is 0.02-0.05 parts by weight, and the content of water is 15-27 parts by weight.

5. The composition according to any one of claims 1 to 4, characterized in that The fine aggregate is quartz sand.

6. A method for preparing mortar, characterized in that: The method is carried out using the components in the composition according to any one of claims 1 to 5, comprising: The components in the main agent and the components in the auxiliary agent are mixed and contacted to obtain mortar.

7. The method according to claim 6, characterized in that The step of mixing and contacting the components in the main agent and the components in the auxiliary agent comprises: (1) subjecting the base component, the powdered calcium oxide in the first component, and the powdered sodium silicate in the first component to a first stirring and mixing process to obtain a powder; and performing a second stirring mixing on the second component and the auxiliary agent to obtain a liquid material; (2) contacting and mixing the powder, the liquid, the styrene-butadiene emulsion and the fine aggregate to obtain a mixture I; (3) contacting and mixing the mixture I with the single-component waterborne polyurethane in the first component II to obtain mortar.

8. The method according to claim 7, characterized in that In step (3), the conditions of contact mixing II include: temperature of 0-20°C, rotation speed of 140-285 rpm, and time of 1-3 min.

9. Mortar prepared by the method according to any one of claims 6 to 8.

10. Use of the mortar according to claim 9 in repairing high-speed railway ballastless tracks in a negative temperature environment.

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