Anti-freezing and anti-seepage concrete and preparation method thereof

Abstract

The invention provides anti-freezing and anti-seepage concrete which comprises the following raw materials in proportion: 980-1050 kg / m < 3 > of broken stone, 180-200 kg / m < 3 > of water, 560-580 kg / m < 3 > of cement, 610-630 kg / m < 3 > of river sand and mPCM, SAP with the cement content being 0.1-0.5% and 1-3 kg / m < 3 > of polypropylene fiber, and the mPCM accounts for 3-12% of the total amount of the river sand and the mPCM. The mPCM, the SAP and the polypropylene fiber in a certain ratio are doped, so that the concrete has good impermeability while the frost resistance of the concrete is greatly improved, and the service life of the concrete in severe environments such as high-latitude and high-altitude cold regions is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to frost-resistant and impermeable concrete and a preparation method thereof. Background Art

[0002] As a kind of transportation infrastructure connecting urban areas, tunnels play an important role in regional economic development, reducing road occupation, and traffic diversion. However, water leakage in the main concrete structure of tunnel projects and freeze-thaw damage to concrete caused by water leakage have always been common quality problems, which not only affect the safety of the structure, but also seriously shorten its service life and cause a lot of economic losses. At present, the existence of a large number of pores and permeation paths in concrete is the main cause of the permeation problem. Although traditional concrete materials have good structural strength and certain anti-seepage properties, they still have great limitations in frost resistance. Especially in high-latitude and high-altitude cold areas, the significant temperature difference between day and night and the extensive permafrost layer pose a continuous erosion challenge to traditional concrete, resulting in the peeling of the material surface, the rupture of the internal structure, and the intensification of carbonization and steel corrosion.

[0003] At present, there are still some deficiencies in the research on the antifreeze and anti-permeability properties of concrete. The Chinese invention patent document with publication number CN118184248A discloses an anti-permeability concrete and a preparation method thereof. By co-blending SAP and polypropylene fibers and controlling their ratio, the anti-permeability performance is improved without reducing the compressive strength. However, this patent only explores the anti-permeability and compressive properties of concrete with the same ratio of cementitious materials under normal conditions, and it is impossible to know whether it has anti-freeze properties. The Chinese invention patent document with publication number CN118184249A discloses an anti-freeze concrete and a preparation method thereof. By doping mPCM to replace part of the river sand, the anti-freeze performance of concrete is improved. However, this patent only explores the addition of a certain proportion of mPCM to improve the anti-freeze performance of concrete, and it is impossible to know whether it has anti-permeability.

[0004] At present, concrete is not dense enough, has too many pores and has infiltration paths, so water can easily pass through the concrete structure, leading to infiltration problems. In cold areas at high latitudes and altitudes, significant temperature differences between day and night and widespread permafrost pose a continuous erosion challenge to traditional concrete. How to control the proportion of concrete materials so that the concrete has both frost resistance and impermeability is a problem that needs to be solved at present. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to make concrete have both frost resistance and anti-seepage performance.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] The first aspect of the present invention provides an antifreeze and impermeable concrete, which comprises raw materials with the following mix proportions: 980 - 1050 kg / m 3 of crushed stones, 180 - 200 kg / m 3 of water, 560 - 580 kg / m 3 of cement, a total of 610 - 630 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1 - 0.5% and 1 - 3 kg / m 3 of polypropylene fiber, wherein mPCM accounts for 3 - 12% of the total amount of river sand and mPCM.

[0008] Beneficial effects: 1. By incorporating a certain proportion of mPCM, SAP and polypropylene fiber, the present invention can greatly improve the antifreeze performance of concrete while still ensuring good impermeability performance of concrete, and prolong the service life of concrete in harsh environments such as high-latitude and high-altitude cold regions.

[0009] 2. By appropriately incorporating mPCM, it can slow down and repair microcracks after multiple freeze-thaw cycles, improve the self-healing ability of the material, and thus improve the long-term mechanical properties of concrete. Adding appropriate amounts of SAP and polypropylene fiber further improves the mechanical properties of concrete. SAP and polypropylene fiber increase the interfacial bonding ability between mPCM and the cement matrix by enhancing the bite force of the aggregate, thereby improving the mechanical properties of concrete.

[0010] 3. The present invention studies the compressive strength and water permeability of concrete after multiple freeze-thaw cycles, and can determine that the antifreeze and impermeability performance of concrete is the best in the pure cement state, and the compressive strength and water permeability of concrete before and after freeze-thaw cycles are better than those of cement incorporated with fly ash and slag powder.

[0011] 4. By changing the mix proportions of SAP and polypropylene fiber, and studying the compressive strength and water permeability of concrete after multiple freeze-thaw cycles, it can be determined that as the number of freeze-thaw cycles increases, the influence laws of SAP and polypropylene fiber on the structural compressive strength and water permeability basically remain unchanged, and appropriate incorporation of SAP and polypropylene fiber can improve the compressive strength and water permeability of concrete under freeze-thaw cycles.

[0012] Preferably, it comprises raw materials with the following mix proportions: 980 - 1050 kg / m 3 of crushed stones, 180 - 200 kg / m 3 of water, 560 - 580 kg / m 3 of cement, a total of 610 - 630 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1% and 1 kg / m 3 of polypropylene fiber, wherein mPCM accounts for 6 - 12% of the total amount of river sand and mPCM.

[0013] Preferably, it comprises raw materials in the following proportions: 980 - 1050 kg / m 3 of crushed stone, 180 - 200 kg / m 3 of water, 560 - 580 kg / m 3 of cement, with a total of 610 - 630 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1%, and 1 kg / m 3 of polypropylene fiber, where mPCM accounts for 9% of the total amount of river sand and mPCM.

[0014] Preferably, it comprises raw materials in the following proportions: 1050 kg / m 3 of crushed stone, 200 kg / m 3 of water, 580 kg / m 3 of cement, with a total of 630 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1%, and 1 kg / m 3 of polypropylene fiber, where mPCM accounts for 9% of the total amount of river sand and mPCM.

[0015] Preferably, it comprises raw materials in the following proportions: 1012 kg / m 3 of crushed stone, 196 kg / m 3 of water, 570 kg / m 3 of cement, with a total of 622 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1%, and 1 kg / m 3 of polypropylene fiber, where mPCM accounts for 9% of the total amount of river sand and mPCM.

[0016] The second aspect of the present invention provides a method for preparing frost - resistant and impermeable concrete, comprising the following steps:

[0017] S1 Prepare raw materials and clean the mixer;

[0018] S2 Add crushed stone, river sand, and cement to the mixer in sequence, start the mixer, and fully stir to make dry - mixed concrete;

[0019] S3 Mix water and mPCM evenly and then add them to the mixer and fully stir to make wet - standby concrete;

[0020] S4 Dilute SAP into a liquid state, mix it with polypropylene fiber, and then add them to the mixer and fully stir to make wet concrete;

[0021] S5 Pour the wet concrete into the test mold for curing and maintenance to make concrete specimens.

[0022] Beneficial effects: The concrete prepared by the present invention can greatly improve the frost resistance of the concrete while still ensuring that the concrete has good impermeability performance.

[0023] Preferably, in the step S2, the stirring time is 90 s.

[0024] Preferably, in the step S3, the stirring time is 180 s.

[0025] Preferably, in the step S4, the stirring time is 180 s.

[0026] Preferably, in the step S5, the curing time is 24 h and the maintenance time is 28 days. Description of the drawings

[0027] Figure 1 is a flowchart of the preparation methods of frost-resistant and impermeable concrete for the examples and comparative examples;

[0028] Figure 2 is a graph of the compressive strength of the concrete for Example 2 and Examples 4 - 11;

[0029] Figure 3 is a graph of the water seepage height of the concrete for Example 2 and Examples 4 - 11;

[0030] Figure 4 is a graph of the compressive strength of the concrete after 100 freeze-thaw cycles for Example 2 and Examples 4 - 11;

[0031] Figure 5 is a graph of the water seepage height of the concrete after 100 freeze-thaw cycles for Example 2 and Examples 4 - 11;

[0032] Figure 6 is a graph of the compressive strength of two kinds of concrete for Examples 1 - 3 and Comparative Example 4; in the figure, P0 represents Comparative Example 4, P6 represents Example 1, P9 represents Example 2, and P12 represents Example 3; where a represents the graph of the compressive strength of the concrete without adding SAP and polypropylene fiber for Examples 1 - 3 and Comparative Example 4; b is the graph of the compressive strength of the concrete for Examples 1 - 3 and Comparative Example 4;

[0033] Figure 7 is a graph of the splitting tensile strength of two kinds of concrete for Examples 1 - 3 and Comparative Example 4; in the figure, P0 represents Comparative Example 4, P6 represents Example 1, P9 represents Example 2, and P12 represents Example 3; where a represents the graph of the compressive strength of the concrete without adding SAP and polypropylene fiber for Examples 1 - 3 and Comparative Example 4; b is the graph of the compressive strength of the concrete for Examples 1 - 3 and Comparative Example 4;

[0034] Figure 8It is the relative mass loss rate curve graph of two kinds of concrete in Examples 1 - 3 and Comparative Example 4; in the graph, P0 represents Comparative Example 4, P6 represents Example 1, P9 represents Example 2, and P12 represents Example 3; where a represents the concrete compressive strength curve graph of Examples 1 - 3 and Comparative Example 4 without adding SAP and polypropylene fiber; b is the concrete compressive strength curve graph of Examples 1 - 3 and Comparative Example 4.

[0035] Figure 9 It is the relative dynamic elastic modulus loss rate curve graph of two kinds of concrete in Examples 1 - 3 and Comparative Example 4; in the graph, P0 represents Comparative Example 4, P6 represents Example 1, P9 represents Example 2, and P12 represents Example 3; where a represents the concrete compressive strength curve graph of Examples 1 - 3 and Comparative Example 4 without adding SAP and polypropylene fiber; b is the concrete compressive strength curve graph of Examples 1 - 3 and Comparative Example 4.

[0036] Figure 10 It is the seepage height curve graph of two kinds of concrete in Examples 1 - 3 and Comparative Example 4; in the graph, P0 represents Comparative Example 4, P6 represents Example 1, P9 represents Example 2, and P12 represents Example 3; where a represents the concrete compressive strength curve graph of Examples 1 - 3 and Comparative Example 4 without adding SAP and polypropylene fiber; b is the concrete compressive strength curve graph of Examples 1 - 3 and Comparative Example 4.

[0037] Figure 11 It is the concrete compressive strength curve graph of Example 2 and Comparative Examples 1 - 3.

[0038] Figure 12 It is the seepage height curve graph of Example 2 and Comparative Examples 1 - 3. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] The test materials, reagents, etc. used in the following embodiments can be obtained from commercial channels without special instructions.

[0041] For those not specified in the embodiments in terms of specific techniques or conditions, they can all be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications.

[0042] Phase change materials (PCMs) are substances that can absorb and release heat at specific temperatures. After microencapsulation, these materials can be more evenly and safely incorporated into concrete. The application of microencapsulated phase change materials (mPCMs) in building materials can regulate the thermal environment of buildings and improve energy efficiency by absorbing and releasing heat. SAP refers to superabsorbent resin.

[0043] Example 1

[0044] This example provides a frost-resistant and impermeable concrete and its preparation method, including raw materials with the following proportions: crushed stone: 980 kg / m 3 , water: 180 kg / m 3 , cement: 560 kg / m 3 , river sand: 574 kg / m 3 , mPCM: 36 kg / m 3 , SAP: 0.56 kg / m 3 and polypropylene fiber 1 kg / m 3 .

[0045] As Figure 1 shown, the preparation method of the above frost-resistant and impermeable concrete specifically includes the following steps:

[0046] S1 Prepare raw materials and clean the mixer;

[0047] S2 Add crushed stone, river sand and cement to the mixer in sequence, start the mixer, and fully stir for 90 s to make dry concrete mixture;

[0048] S3 Mix water and mPCM evenly and then add them to the mixer and fully stir for 180 s to make wet standby concrete;

[0049] S4 Dilute SAP into a liquid state, mix it with polypropylene fiber and then add them to the mixer and fully stir for 180 s to make wet concrete;

[0050] S5 Pour the wet concrete into the test mold, cure for 24 h and maintain for 28 days to make concrete specimens.

[0051] The water-binder ratio of the concrete prepared with the above raw materials is 0.32, and the sand ratio is 0.37.

[0052] Example 2

[0053] This example provides a frost-resistant and impermeable concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3, mPCM: 56 kg / m 3 , SAP: 0.57 kg / m 3 and polypropylene fiber 1 kg / m 3 .

[0054] The preparation method of the concrete in this example is the same as that in Example 1, and will not be repeated here.

[0055] The water-binder ratio of the concrete prepared with the above raw materials is 0.34 and the sand ratio is 0.36.

[0056] Example 3

[0057] This example provides a frost-resistant and impermeable concrete and its preparation method, including the following raw materials in proportion: crushed stone: 1050 kg / m 3 , water: 200 kg / m 3 , cement: 580 kg / m 3 , river sand: 554 kg / m 3 , mPCM: 76 kg / m 3 , SAP: 0.58 kg / m 3 and polypropylene fiber 1 kg / m 3 .

[0058] The preparation method of the concrete in this example is the same as that in Example 1, and will not be repeated here.

[0059] The water-binder ratio of the concrete prepared with the above raw materials is 0.34 and the sand ratio is 0.35.

[0060] Example 4

[0061] This example provides a frost-resistant and impermeable concrete and its preparation method, including the following raw materials in proportion: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 1.71 kg / m 3 and polypropylene fiber 1 kg / m 3 .

[0062] The preparation method of the concrete in this example is the same as that in Example 1, and will not be repeated here. The water-binder ratio and sand ratio of the concrete prepared in this example are the same as those in Example 2.

[0063] Example 5

[0064] This embodiment provides a frost-resistant and impermeable concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 2.85 kg / m 3 and polypropylene fiber 1 kg / m 3 .

[0065] The preparation method of the concrete in this embodiment is the same as that in Embodiment 1 and will not be repeated here.

[0066] Embodiment 6

[0067] This embodiment provides a frost-resistant and impermeable concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 0.57 kg / m 3 and polypropylene fiber 2 kg / m 3 .

[0068] The preparation method of the concrete in this embodiment is the same as that in Embodiment 1 and will not be repeated here. The water-binder ratio and sand ratio of the prepared concrete in this embodiment are the same as those in Embodiment 2.

[0069] Embodiment 7

[0070] This embodiment provides a frost-resistant and impermeable concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 1.71 kg / m 3 and polypropylene fiber 2 kg / m 3 .

[0071] The preparation method of the concrete in this embodiment is the same as that in Embodiment 1 and will not be repeated here. The water-binder ratio and sand ratio of the prepared concrete in this embodiment are the same as those in Embodiment 2.

[0072] Embodiment 8

[0073] This embodiment provides an anti-freezing and anti-seepage concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 2.85 kg / m 3 and polypropylene fiber 2 kg / m 3 .

[0074] The preparation method of the concrete in this embodiment is the same as that in Example 1 and will not be repeated here. The water-binder ratio and sand ratio of the concrete prepared in this embodiment are the same as those in Example 2.

[0075] Example 9

[0076] This embodiment provides an anti-freezing and anti-seepage concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 0.57 kg / m 3 and polypropylene fiber 3 kg / m 3 .

[0077] The preparation method of the concrete in this embodiment is the same as that in Example 1 and will not be repeated here. The water-binder ratio and sand ratio of the concrete prepared in this embodiment are the same as those in Example 2.

[0078] Example 10

[0079] This embodiment provides an anti-freezing and anti-seepage concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 1.71 kg / m 3 and polypropylene fiber 3 kg / m 3 .

[0080] The preparation method of the concrete in this embodiment is the same as that in Example 1 and will not be repeated here. The water-binder ratio and sand ratio of the concrete prepared in this embodiment are the same as those in Example 2.

[0081] Example 11

[0082] This example provides an anti-freezing and anti-seepage concrete and its preparation method, including raw materials with the following ratios: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 2.85 kg / m 3 and polypropylene fiber 3 kg / m 3 .

[0083] The preparation method of the concrete in this example is the same as that in Example 1 and will not be repeated here. The water-binder ratio and sand ratio of the concrete prepared in this example are the same as those in Example 2.

[0084] Comparative Example 1

[0085] This comparative example provides an anti-freezing and anti-seepage concrete and its preparation method, including raw materials with the following ratios: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 484 kg / m 3 , fly ash: 86 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 0.57 kg / m 3 and polypropylene fiber 1 kg / m 3 .

[0086] The preparation method of the concrete in this comparative example is the same as that in Example 1 and will not be repeated here.

[0087] Comparative Example 2

[0088] This comparative example provides an anti-freezing and anti-seepage concrete and its preparation method, including raw materials with the following ratios: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 484 kg / m 3 , mineral powder: 86 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 0.57 kg / m 3 and polypropylene fiber 1 kg / m 3 .

[0089] The preparation method of the concrete in this comparative example is the same as that in Example 1 and will not be repeated here.

[0090] Comparative Example 3

[0091] This comparative example provides an antifreeze and impermeable concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 484 kg / m 3 , fly ash: 57 kg / m 3 , mineral powder: 29 kg / m 3 , river sand: 566 kg / m 3 , mPCM: 56 kg / m 3 , SAP: 0.57 kg / m 3 and polypropylene fiber 1 kg / m 3 .

[0092] The preparation method of the concrete in this comparative example is the same as that of Example 1 and will not be repeated here.

[0093] Comparative Example 4

[0094] This comparative example provides an antifreeze and impermeable concrete and its preparation method, including raw materials with the following proportions: crushed stone: 1012 kg / m 3 , water: 196 kg / m 3 , cement: 570 kg / m 3 , river sand: 622 kg / m 3 , mPCM: 0, SAP: 0.57 kg / m 3 , and polypropylene fiber 1 kg / m 3 .

[0095] The preparation method of the concrete in this comparative example is the same as that of Example 1 and will not be repeated here.

[0096] Experimental Example

[0097] Perform performance tests on the concrete specimens prepared in Examples 1 - 10 and Comparative Examples 1 - 4.

[0098] 1. Perform performance tests on the concrete specimens prepared in Example 2 and Examples 4 - 10. By changing the proportions of SAP and polypropylene fiber, determine the optimal proportion state of SAP and polypropylene fiber for the antifreeze and impermeable properties of the concrete. Table 1 shows the compressive strength and water penetration height parameters of the concrete in Example 2 and Examples 4 - 10. Specifically as Figures 2 - 5 shown.

[0099] Table 1

[0100]

[0101] As shown in Table 1 andFigure 2 As shown, the ranking of the compressive strength of concrete in the initial stage and after 100 freeze-thaw cycles changes little. When 0.1% of SAP based on cement and 1 kg / m 3 of polypropylene fiber are incorporated, the compressive strength is the maximum. As Figure 4 shown, when 0.1% of SAP based on cement is incorporated, after 100 freeze-thaw cycles, with the increase of the polypropylene fiber content, the compressive strength shows a gradually decreasing trend; when SAP is 0.3% of cement, after 100 freeze-thaw cycles, with the increase of the polypropylene fiber content, the compressive strength shows a trend of first increasing and then decreasing; when SAP is 0.5% of cement, after 100 freeze-thaw cycles, with the increase of the polypropylene fiber content, the compressive strength shows a gradually increasing trend, but the increasing trend weakens. Thus, with the increase of the number of freeze-thaw cycles, the influence law of SAP and polypropylene fiber on the compressive strength of concrete remains basically unchanged. When 0.1% of SAP based on cement and 1 kg / m 3 of polypropylene fiber are incorporated, the compressive strength of concrete is the maximum. Excessive incorporation of SAP and polypropylene fiber cannot improve the compressive strength of concrete under freeze-thaw cycles.

[0102] As shown in Table 1 and Figure 3 shown, the ranking of the water penetration height of concrete in the initial stage and after 100 freeze-thaw cycles remains unchanged. When 0.1% of SAP based on cement and 1 kg / m 3 of polypropylene fiber are incorporated, the water penetration height is the lowest. As Figure 5 shown, with the increase of the incorporated SAP and polypropylene fiber content, the water penetration height gradually increases and the anti-seepage ability gradually decreases. Thus, with the increase of the number of freeze-thaw cycles, the influence law of SAP and polypropylene fiber on the water seepage performance of concrete remains basically unchanged. When 0.1% of SAP based on cement and 1 kg / m 3 of polypropylene fiber are incorporated, the water penetration height is the lowest and the anti-seepage performance is the best. Excessive incorporation of SAP and polypropylene fiber cannot improve the water seepage performance of concrete under freeze-thaw cycles.

[0103] 2. Performance tests were carried out on the concrete specimens prepared by Examples 1 - 3 and Comparative Example 4. By comparing the frost resistance and impermeability of Examples 1 - 3 and Comparative Example 4 with those of Examples 1 - 3 and Comparative Example 4 without adding SAP and polypropylene fiber, and by changing the ratio of mPCM in the total amount of river sand and mPCM, it was determined when the ratio of mPCM in the total amount of river sand and mPCM was added, the best frost resistance and impermeability of concrete were obtained.

[0104] As Figure 6 shown in a - b, when 0.1% of SAP based on cement and 1 kg / m of polypropylene fiber are added 3After that, the compressive strength of concrete at each number of freeze-thaw cycles has increased. After 100 freeze-thaw cycles, the compressive strengths of P0, P6, P9, and P12 have increased by 7.8%, 13.9%, 81.7%, and 60.6% respectively compared to when no SAP and polypropylene fiber were added. After adding SAP and polypropylene fiber, after 100 freeze-thaw cycles, the compressive strengths of P6, P9, and P12 have all increased compared to P0, by 71.8%, 91.9%, and 21.8% respectively. The compressive strength of P9 is the highest because adding SAP and polypropylene fiber increases the bite force of the aggregate, thereby enhancing the resistance to the hydrothermal effect.

[0105] However, if an excessive amount of mPCM such as P12 is added, the compressive strength decreases compared to P6 and P9. This is because appropriately incorporating mPCM can slow down and repair microcracks after multiple freeze-thaw cycles, improve the self-healing ability of the material, and thus enhance its long-term mechanical properties. But after excessive incorporation of mPCM, mPCM absorbs and stores the heat released during the cement hydration reaction, which leads to a decrease in the internal temperature, slows down the process of the hydration reaction, causing a large number of cement particles to fail to transform into hydration products such as C-S-H. In addition, the decrease in temperature also results in a reduction in the fluidity of the water in the pores, thereby affecting the diffusion and distribution of the hydration products inside, leading to uneven pore distribution and an increase in the number of pores, reducing the bite force of the aggregate, and decreasing the resistance to the hydrothermal effect. At this time, the compressive strength of the concrete can be increased by adding a certain amount of SAP and polypropylene fiber. It can be seen that the P9 mix ratio is the best, which can not only slow down the damage of the freeze-thaw cycle to the compressive strength of the matrix but also reduce the construction cost.

[0106] As Figure 7 As shown in a-b, after adding 0.1% of SAP by mass of cement and 1 kg / m of polypropylene fiber 3 After that, the splitting tensile strength of concrete at each number of freeze-thaw cycles has increased. Due to the weak interfacial bond between mPCM and the cement matrix, cracks are prone to form at these interfaces under tensile stress, thereby reducing the splitting tensile strength. After adding SAP and polypropylene fiber, the interfacial bonding ability between mPCM and the cement matrix is increased. In the initial stage, the splitting tensile strengths of P0, P6, P9, and P12 concrete have increased by 22.6%, 21.3%, 15.0%, and 14.8% respectively compared to before; after 100 freeze-thaw cycles, they have increased by 81.8%, 118.0%, 690.5%, and 415.4% respectively.

[0107] After 100 freeze-thaw cycles, the splitting tensile strength of P6, P9, and P12 increased by 565.0%, 730.0%, and 235.0%, respectively, relative to that of P0. At this time, the splitting tensile strength of P9 was the highest, indicating that the addition of P9 was optimal, which was beneficial to reducing the damage of temperature stress to the matrix, improving the splitting tensile strength of concrete while reducing the construction cost.

[0108] like Figure 8 It can be seen from ab that when SAP is 0.1% of cement and polypropylene fiber is 1kg / m 3 After the addition of SAP and polypropylene fibers, the relative mass loss rate of concrete slowed down in the initial freeze-thaw cycle. This is because the microcracks between concrete were reduced after adding SAP and polypropylene fibers, which reduced the proportion of water absorption and weight gain. After 100 freeze-thaw cycles, the relative mass loss rates of P6, P9, and P12 were reduced by 67.0%, 74.6%, and 39.4% respectively relative to P0. The relative mass loss rate of P9 was the lowest. This is because the high energy storage density of mPCM itself effectively increases the total heat capacity of the matrix, thereby storing heat at high temperatures and releasing heat at low temperatures, reducing the mass loss caused by temperature cracks and frozen water expansion force. Appropriate addition can effectively improve the antifreeze performance of concrete. The relative mass loss rate of concrete decreased under each number of freeze-thaw cycles. After 100 freeze-thaw cycles, the relative mass loss rates of P0, P6, P9 and P12 concrete decreased by 17.2%, 22.6%, 65.1% and 36.6% respectively compared with before. The decrease of P9 was the largest because the addition of SAP and polypropylene fiber could reduce the generation of microcracks between concrete, further reduce the mass loss of concrete, and improve the frost resistance and crack resistance. The relative mass loss rate of P9 concrete was the lowest.

[0109] like Figure 9 It can be seen from ab that when SAP is 0.1% of cement and polypropylene fiber is 1kg / m 3After 100 freeze-thaw cycles, the relative dynamic elastic modulus loss rates of P6, P9, and P12 compared to P0 decreased by 46.7%, 49.1%, and 18.3% respectively. The relative dynamic elastic modulus loss rate of P9 was the lowest because an appropriate amount of mPCM can be regarded as micro-pores harmless to the matrix, and its heat energy storage and release mechanism optimized the temperature stress distribution of the matrix material during the freeze-thaw cycle, effectively avoiding the formation of cracks in stress concentration areas such as the interfacial transition zone (ITZ) and bubble aggregation sites. The relative mass loss rates of the concrete at each freeze-thaw cycle decreased. After 100 freeze-thaw cycles, the relative dynamic elastic modulus loss rates of P0, P6, P9, and P12 concrete decreased by 8.8%, 11.2%, 43.5%, and 29.1% respectively compared to before. The decrease of P9 was the largest because after adding SAP and polypropylene fibers, it can effectively slow down the reduction of interfacial adhesion between materials and the generation of cracks between particles caused by excessive addition of mPCM, thereby enhancing the internal connectivity of the matrix and reducing the loss of dynamic elastic modulus during freeze-thaw cycles.

[0110] As Figure 10 a - b shows that after adding 0.1% of SAP to the cement and 1 kg / m of polypropylene fiber 3 After 100 freeze-thaw cycles, the water penetration heights of P0, P6, P9, and P12 decreased by 8.6%, 10.5%, 15.6%, and 14.7% respectively compared to when SAP and polypropylene fibers were not added. After 100 freeze-thaw cycles, the water penetration heights of P6, P9, and P12 compared to P0 decreased by 7.9%, 10.6%, and 1.9% respectively. The water penetration height of P9 was the lowest because when an appropriate amount of SAP and polypropylene fibers were incorporated, the special spatial network structure of SAP has extremely high water absorption and water retention capabilities. As an efficient curing agent, it can effectively avoid problems such as water loss cracking caused by hydration during long-term freeze-thaw cycles inside the concrete. Incorporating an appropriate amount of polypropylene fibers into the concrete can improve its internal structure, fill the pores, effectively prevent concrete segregation and bleeding, and inhibit the generation of cracks. It can be seen that the mix proportion of P9 reaches the optimal state, improving the frost resistance and impermeability while ensuring the concrete strength, and extending the service life of the concrete structure.

[0111] 3. Performance tests were carried out on the concrete specimens prepared through Example 2 and Comparative Examples 1 - 3. By changing the mix ratios of cement, fly ash, and slag powder, which mix ratio state has the best frost resistance and impermeability of the concrete.

[0112] As Figure 11As shown, the compressive strength of the concrete in Example 2 in the initial state is close to that of the concrete in Comparative Examples 1 and 3 in the initial state and is almost equal when the freeze-thaw cycles reach 25 times. This is because a certain amount of fly ash and ground granulated blast-furnace slag are incorporated in Comparative Examples 1 and 3. The early strength of fly ash and ground granulated blast-furnace slag cement is low, and the later strength increases relatively fast. However, as the number of freeze-thaw cycles increases, the compressive strength of the concrete in Example 2 is significantly higher than that of other solutions, and the difference in the compressive strength of the concrete in Comparative Examples 1-3 becomes smaller. This is because the cement incorporated with fly ash and ground granulated blast-furnace slag has poor frost resistance. As the number of freeze-thaw cycles increases, some structures are damaged, affecting the compressive strength of the structure.

[0113] As Figure 12 shown, in the early stage of freeze-thaw cycles, the water seepage height of the concrete in Comparative Example 1 is the lowest. This is because a certain amount of fly ash is incorporated, and fly ash cement has good crack resistance, which reduces the water seepage height of the concrete to a certain extent. However, as the number of freeze-thaw cycles increases, the water seepage height of the concrete in Example 2 is significantly lower than that of other solutions, and the difference in the water seepage height of the concrete in Comparative Examples 1-3 becomes smaller. This further shows that the cement incorporated with fly ash and ground granulated blast-furnace slag has poor frost resistance. As the number of freeze-thaw cycles increases, some structures are damaged, affecting the water seepage performance of the structure.

[0114] In summary, when the mPCM incorporated accounts for 9% of the total amount of river sand and mPCM, the SAP is 0.1% of the cement, and the polypropylene fiber is 1 kg / m 3 the concrete has the best performance in all aspects and has good frost resistance and water impermeability.

[0115] The above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the present invention in each example.

Claims

1. An anti-freezing and anti-seepage concrete, characterized in that, Comprising raw materials in the following proportions: 980 - 1050 kg / m 3 of crushed stone, 180 - 200 kg / m 3 of water, 560 - 580 kg / m 3 of cement, with a total amount of 610 - 630 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1 - 0.5%, and 1 - 3 kg / m 3 of polypropylene fiber, where mPCM accounts for 3 - 12% of the total amount of river sand and mPCM.

2. The anti-freezing and anti-seepage concrete according to claim 1, wherein Comprising raw materials in the following proportions: 980 - 1050 kg / m 3 of crushed stone, 180 - 200 kg / m 3 of water, 560 - 580 kg / m 3 of cement, with a total of 610 - 630 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1%, and 1 kg / m 3 of polypropylene fiber, where mPCM accounts for 6 - 12% of the total amount of river sand and mPCM.

3. The frost-resistant and impermeable concrete according to claim 2, characterized in that, Comprising raw materials in the following proportions: 980 - 1050 kg / m 3 of crushed stone, 180 - 200 kg / m 3 of water, 560 - 580 kg / m 3 of cement, with a total of 610 - 630 kg / m 3 of river sand and mPCM, 0.1% SAP by cement content, and 1 kg / m 3 of polypropylene fiber, where mPCM accounts for 9% of the total amount of river sand and mPCM.

4. The anti-freezing and anti-seepage concrete according to claim 3, wherein, Raw materials including the following proportions: 1050 kg / m 3 of crushed stone, 200 kg / m 3 of water, 580 kg / m 3 of cement, with a total of 630 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1%, and 1 kg / m 3 of polypropylene fiber, where mPCM accounts for 9% of the total amount of river sand and mPCM.

5. The anti-freezing and anti-seepage concrete according to claim 3, characterized in that, Raw materials including the following proportions: 1012 kg / m 3 of crushed stone, 196 kg / m 3 of water, 570 kg / m 3 of cement, with a total of 622 kg / m 3 of river sand and mPCM, SAP with a cement content of 0.1%, and 1 kg / m 3 of polypropylene fiber, where mPCM accounts for 9% of the total amount of river sand and mPCM.

6. The method for preparing frost-resistant and impermeable concrete according to any one of claims 1-5, characterized in that, It includes the following steps: S1 Prepare raw materials and clean the mixer; S2 Add crushed stones, river sand and cement into the mixer in sequence, start the mixer, and fully stir to make dry-mixed concrete; S3 Mix water and mPCM evenly and then add them into the mixer and fully stir to make wet standby concrete; S4 Dilute SAP into a liquid state, mix it with polypropylene fibers and then add them into the mixer and fully stir to make wet concrete; S5 Pour the wet concrete into the test mold for curing and maintenance to make concrete specimens.

7. The method for preparing frost-resistant and impermeable concrete according to claim 6, characterized in that, In S2, the stirring time is 90s.

8. The method for preparing frost-resistant and impermeable concrete according to claim 6, characterized in that, In S3, the stirring time is 180s.

9. The preparation method of the antifreeze and impermeable concrete according to claim 6, wherein, In S4, the stirring time is 180s.

10. The method for preparing frost-resistant and impermeable concrete according to claim 6, wherein, In S5, the curing time is 24h and the maintenance time is 28 days.

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