Super slow-setting concrete and preparation method thereof

Abstract

The present application relates to the technical field of concrete, and specifically discloses a super-slow setting concrete and a preparation method thereof. The super-slow setting concrete disclosed in the present application comprises the following components in parts by weight: 390-450 parts of cementitious materials; 720-840 parts of sand; 920-1080 parts of crushed stone; 9-13 parts of water reducer; 8-12 parts of retarder; 150-200 parts of water; wherein the cementitious materials comprise cement, fly ash and slag powder in a weight ratio of (280-320): (70-90): (37-57). The present application also provides a preparation method for the above-mentioned super-slow setting concrete. The super-slow setting concrete obtained by using the formula and preparation method provided in the present application has a longer setting time and a lower water bleeding rate, a better slump retention effect, and a better compressive strength after final setting.

Description

Technical Field

[0001] The present application relates to the technical field of concrete, and in particular to a super slow-setting concrete and a preparation method thereof. Background Art

[0002] Due to the increasing shortage of land resources in my country, the rapid development of urban high-rise buildings and rail transit construction, the underground space development projects are growing, and the depth of basement foundation pits is constantly expanding. The cover-excavation reverse construction method is a commonly used construction method. Its process characteristics are small deformation of the retaining structure, small impact on the ground, and rapid restoration of the original ground traffic. The principle of this method is to first construct the retaining system (piles, ground-connected walls) and the load-bearing system of the top plate (steel pipe columns), then construct the top plate structure, and reserve an excavation opening on the top plate, complete the earth excavation and side wall, middle plate and bottom plate structure construction from top to bottom, and finally seal the reserved holes in the top plate, lay the waterproof layer and backfill the earth above the top plate, and finally form a complete permanent structure.

[0003] The load-bearing system of the roof generally adopts the hydraulic vertical insertion method (HPE), which uses a fully hydraulic casing machine and an automatic positioner to complete the lifting, vertical insertion and core concrete pouring of the steel pipe column, and timely protects the steel pipe column.

[0004] At present, the hydraulic vertical insertion method has high quality requirements for concrete. Concrete needs to have good workability and fluidity. This is because underwater concrete pouring construction does not have vibration conditions. It relies on the concrete's own weight to flow and flatten and compact at the bottom of the pile foundation. If the fluidity is poor, it will cause difficulty in pouring, pipe blockage, and failure to pour normally, and even broken piles will occur, causing major quality accidents; at the same time, the concrete poured underwater must have good cohesion and water retention to prevent the segregation and bleeding of concrete. During the pouring process, gravel will gather locally in the conduit, causing "stuck pipes" and causing quality accidents; the concrete has good workability during pouring, and the slump is 200±20mm; after the concrete pouring is completed, when the steel pipe column is inserted, the concrete has no large amount of bleeding, good homogeneity, and no stratification. Second, the concrete needs to have good compressive strength. With the addition of retarders, the concrete strength will be reduced, and the mix design must meet the 28-day compressive strength requirements. Third, the concrete needs to have a long setting time. Considering the need to insert the bored pile into the steel pipe column, the concrete of the bored pile must have an initial setting time of no less than 48 hours. At the same time, the concrete slump from the time of transportation to the time of insertion into the steel pipe column must be no less than 16cm. If this requirement is not met, the permanent steel pipe column cannot be pressed in smoothly, the pile foundation will be invalid, and the redesign and construction will be required, causing huge losses. At the same time, the setting time cannot be too long, otherwise the steel pipe column stabilization equipment will be occupied for too long, affecting the progress of the project. Summary of the invention

[0005] In order to prolong the setting time of concrete, improve the slump retention effect, and ensure the compressive strength of concrete, the present application provides a super slow-setting concrete and a preparation method thereof.

[0006] The present application discloses a super slow-setting concrete, comprising the following components in parts by weight: 390-450 parts of cementitious material; 720-840 parts of sand; 920-1080 parts of crushed stone; 9-13 parts of water reducing agent; 8-12 parts of retarder; 150-200 parts of water;

[0007] The cementitious material includes cement, fly ash and slag powder in a weight ratio of (280-320):(70-90):(37-57).

[0008] The present application utilizes cement, fly ash, and slag powder in a suitable weight ratio as cementitious materials, and sand, crushed stone, water reducer, and retarder as raw materials for super-slow-setting concrete. By controlling the amount of each raw material, the prepared super-slow-setting concrete has a longer setting time and a lower water bleeding rate, a better slump retention effect, and a higher compressive strength after final setting.

[0009] Preferably, the cement is P·O 42.5 cement.

[0010] Preferably, the fly ash is Class F II fly ash with a fineness of 15.0%, a water requirement ratio of 98%, and a loss on ignition of 3.8%.

[0011] Preferably, the specification parameters of the slag powder are: specific surface area 442m2 / kg, fluidity ratio 99%, 7d activity index 77%, and 28d activity index 96%.

[0012] In a specific embodiment, the weight ratio of cement, fly ash and slag powder can be 280:90:57, 280:70:51, 280:80:37, 295:81:51, 295:70:57, 295:90:37, 320:70:37, 320:80:57, 320:90:51.

[0013] In some specific embodiments, the weight ratio of cement, fly ash and slag powder can also be 280:(70-80):57, 280:(80-90):51, 280:(70-90):37, (280-295):81:51, 295:(70-81):57, 295:90:(37-51), 320:(70-80):37, 320:80:(37-51), 320:90:(51-57).

[0014] The present application selects the above-mentioned high-quality sand and fly ash and cement as cementitious materials, which can effectively reduce the yield stress and plastic viscosity of concrete and improve fluidity; on the premise of ensuring the workability of concrete, it can effectively reduce the water consumption of concrete mixture and improve the guarantee rate of concrete strength. At the same time, the present application further improves the comprehensive performance of super slow-setting concrete by controlling the weight ratio of cement, fly ash and slag powder.

[0015] Preferably, the sand comprises artificial sand and natural sand in a weight ratio of (400-460):(320-380).

[0016] Preferably, the artificial sand has a fineness modulus of 2.8, a stone powder content of 5.0%, a mud block content of 0%, and an MB value of 0.75.

[0017] Preferably, the fineness modulus of the natural sand is 2.4, the mud content is 2.7%, and the mud block content is 0%.

[0018] In a specific embodiment, the weight ratio of the artificial sand to the natural sand may be 400:320, 400:355, 400:380, 433:320, 433:355, 433:380, 460:320, 460:355, 460:380.

[0019] In some specific embodiments, the weight ratio of the artificial sand to the natural sand can also be 400:(320-355), 400:(355-380), 400:380, (400-433):320, 433:(355-380), 433:(320-355), (433-460):320, (433-460):355, 460:(355-380).

[0020] As a major skeleton material in concrete, the quality of fine aggregate will directly affect the performance of concrete. The inventors of the present application found that when natural sand is used as fine aggregate, the powder in natural sand has a large adsorption capacity for polycarboxylic acid water-reducing agent, and the powder in artificial sand has a lower adsorption capacity for polycarboxylic acid water-reducing agent than cement. Artificial sand has obvious advantages in reducing the dosage of admixtures, but artificial sand has a small adsorption capacity for admixtures and is more sensitive to fluctuations in the dosage of admixtures, which can easily cause segregation in the actual production process. After experimental analysis, the present application selects artificial sand and natural sand in the above-mentioned weight ratio as fine aggregate, which can reduce the water seepage rate and thereby improve the performance of super-slow setting concrete in HPE construction.

[0021] Preferably, the water reducer is a polycarboxylate water reducer.

[0022] In a specific embodiment, the weight parts of the water reducing agent can be 9 parts, 11 parts, or 13 parts.

[0023] Water reducer affects the adsorption of concrete materials and causes loss of fluidity. Polycarboxylate water reducer has super-long side chains, which can ensure that super-slow setting concrete does not bleed or lose water under long-term slow setting conditions. The present application adjusts the dosage of polycarboxylate water reducer itself and uses it in combination with other raw materials, thereby improving the water retention capacity of super-slow setting concrete.

[0024] Preferably, the retarder comprises sodium gluconate and sodium potassium tartrate in a weight ratio of (7-9):(1-3).

[0025] Furthermore, the retarder comprises sodium gluconate, sodium potassium tartrate and methyl cellulose in a weight ratio of (7-9):(1-3):(0.5-1.5).

[0026] In a specific embodiment, the weight ratio of sodium gluconate, potassium sodium tartrate and methylcellulose can be 7:1:0.5, 7:2:1, 7:3:1.5, 8:1:0.5, 8:2:1, 8:3:1.5, 9:1:0.5, 9:2:1, 9:3:1.5.

[0027] In some specific embodiments, the weight ratio of sodium gluconate, potassium sodium tartrate and methylcellulose can also be 7:(1-2):0.5, 7:(2-3):1, 7:3:(0.5-1.5), 8:(1-2):0.5, 8:2:(1-1.5), 8:(2-3):1.5, (7-8):1:0.5, (8-9):2:1, 9:(1-3):1.5.

[0028] Furthermore, the viscosity of the methyl cellulose is 350-550 mPa.s.

[0029] Hydroxycarboxylates and polysaccharides act as retarders and can inhibit the hydration of tricalcium aluminate, tricalcium silicate and tetracalcium aluminoferrate in cement clinker in an all-round way, which greatly inhibits the hydration of cement within 24 hours, greatly reduces the free water consumption, hinders the hydration of cement, slows down the hydration rate of cement, and thus plays a retarding role and improves the fluidity retention ability.

[0030] The inventors of the present application have found that adding methyl cellulose in combination with sodium gluconate and potassium sodium tartrate as a retarder can effectively delay the hydration time of the gel material, further promote the retarding effect, and reduce the setting time of concrete.

[0031] Preferably, the crushed stone is a continuously graded crushed stone of 5-25 mm, with a mud content of 0.7%, a mud block content of 0%, and a needle-like content of 5%.

[0032] Preferably, the super slow setting concrete further comprises 5-8 parts by weight of a water retaining agent; the water retaining agent comprises polysorbate 40 and polyethyleneimine.

[0033] Furthermore, the water retaining agent comprises polysorbate 40 and polyethyleneimine in a weight ratio of (2-4):(3-5).

[0034] After the use of sand, gravel and water reducing agent, super slow setting concrete will experience segregation and bleeding. The present application uses polysorbate 40 and polyethyleneimine as water retaining agents, which can solve the segregation and bleeding problems caused by the addition of a large amount of retarder to concrete, thereby improving the stability of the fresh concrete during use.

[0035] Furthermore, the specific surface area is 420-460 m2 / kg, the fluidity ratio is 99%, the 7d activity index is 77%, and the 28d activity index is 96%.

[0036] On the other hand, the present application also provides a method for preparing the above-mentioned super slow setting concrete, which specifically comprises the following steps:

[0037] The cement, the fly ash, the slag powder, the sand, the crushed stone and 70-80 wt % of the required water are mixed and stirred uniformly to obtain a primary mixed material;

[0038] Mixing and stirring other raw material components and the remaining water to obtain a premixed material;

[0039] The premixed material is added into the primary mixed material for stirring to obtain the super slow setting concrete.

[0040] In the preparation method of the super-slow setting concrete provided in the present application, cement, fly ash and slag powder are used as gel materials and mixed with sand and crushed stone to obtain a primary mixed material; then a premix composed of other raw materials is added; the water reducer can be completely dispersed on the outer surface of the gel material, which is beneficial for the retarder to penetrate into the raw material components, thereby enhancing the fluidity, water retention and stability of the freshly mixed concrete, effectively prolonging the initial setting time of the super-slow setting concrete, and at the same time ensuring the compressive strength of the super-slow setting concrete.

[0041] In summary, the technical solution of this application has the following effects:

[0042] The present application utilizes cement, fly ash, and slag powder in a suitable weight ratio as cementitious materials, and sand, crushed stone, water reducer, and retarder as raw materials for super-slow-setting concrete. By controlling the amount of each raw material, the prepared super-slow-setting concrete has a longer setting time and a lower water bleeding rate, a better slump retention effect, and a higher compressive strength after final setting.

[0043] The present application further improves the performance of super-slow-setting concrete by selecting artificial sand and natural sand in a suitable weight ratio, screening the type and proportion of retarders, and adding water-retaining agents. DETAILED DESCRIPTION

[0044] In a first aspect, the present application provides a super slow setting concrete, comprising the following components in parts by weight: 390-450 parts of cementitious material; 720-840 parts of sand; 920-1080 parts of crushed stone; 9-13 parts of water reducer; 8-12 parts of retarder; 150-200 parts of water; wherein the cementitious material comprises cement, fly ash and slag powder in a weight ratio of (280-320): (70-90): (37-57).

[0045] Specifically, the sand includes artificial sand and natural sand in a weight ratio of (400-460):(320-380); and the water reducing agent is a polycarboxylate water reducing agent.

[0046] The retarder comprises sodium gluconate and potassium sodium tartrate in a weight ratio of (7-9):(1-3); further, the retarder comprises sodium gluconate, potassium sodium tartrate and methyl cellulose in a weight ratio of (7-9):(1-3):(0.5-1.5); further, the viscosity of the methyl cellulose is 350-550 mPa.s.

[0047] The crushed stone is a continuously graded crushed stone with a size of 5-25 mm.

[0048] Furthermore, the super slow setting concrete also includes 5-8 parts by weight of a water retaining agent; the water retaining agent includes polysorbate 40 and polyethyleneimine in a weight ratio of (2-4):(3-5).

[0049] At the same time, the specifications of slag powder are: specific surface area 420-460m2 / kg, fluidity ratio 99%, 7d activity index 77%, 28d activity index 96%.

[0050] On the other hand, the present application also provides a method for preparing the above-mentioned super slow setting concrete, which specifically comprises the following steps: mixing and stirring cement, fly ash, slag powder, sand, crushed stone and 70-80wt% of required water to obtain a primary mixed material;

[0051] Mixing and stirring other raw material components and the remaining water to obtain a premixed material;

[0052] The premixed material is added to the primary mixed material for mixing to obtain super slow setting concrete.

[0053] The present application is further described in detail below in conjunction with examples, comparative examples and performance testing experiments. These examples should not be construed as limiting the scope of protection claimed in the present application.

[0054] The cement used in this application is P·O 42.5 cement produced by Tangshan Hongtai Cement Co., Ltd., with a specific surface area of ​​343m2 / kg and a standard consistency of 28.0%; the fly ash is F-class II fly ash, with a fineness of 15.0%, a water requirement of 98%, and a loss on ignition of 3.8%; the sand is Chengde Juyuan artificial sand and Hebei Fengning natural sand, with an artificial sand fineness modulus of 2.8, a stone powder content of 5.0%, a mud content of 0%, an MB value of 0.75, and a methylene blue test quick test pass; the natural sand fineness modulus is 2.6, the mud content is 4.0%, and the mud content is 0%; the crushed stone is Chengde Juyuan 5-25mm continuous grading crushed stone, with a mud content of 0.4%, a mud content of 0%, and a needle-like content of 1%; the water reducer is HS-209 polycarboxylate water reducer; methyl cellulose and polyethyleneimine are purchased from Shanghai Yuanye Biotechnology Co., Ltd. The remaining raw materials can be obtained commercially.

[0055] Example

[0056] Examples 1-7

[0057] Examples 1-7 each provide a super slow-setting concrete.

[0058] The dosage of each component in the super slow setting concrete in the above embodiment is shown in Table 1. The preparation method of the super slow setting concrete is as follows:

[0059] According to the amount of each component in Table 1, cement, fly ash, slag powder, sand, crushed stone and 75wt% of the required water are mixed and stirred to obtain a primary mixed material;

[0060] Sodium gluconate, potassium sodium tartrate and methyl cellulose (viscosity 350-550 mPa.s) were mixed in a weight ratio of 8:2:1, and then 11 g was weighed as a retarder;

[0061] Mix and stir the HS-209 polycarboxylate water reducer, retarder and remaining water to obtain a premixed material;

[0062] The premixed material is added to the primary mixed material for mixing to obtain super slow setting concrete.

[0063] Table 1 The amount of each component in Examples 1-7

[0064]

[0065] Example 8

[0066] This embodiment provides a super slow-setting concrete.

[0067] The difference between this embodiment and embodiment 1 is that sodium gluconate, potassium sodium tartrate and methyl cellulose (viscosity of 350-550 mPa.s) are mixed in a weight ratio of 7:3:1.5, and then 11 g is weighed as a retarder; the other components of the super-slow setting concrete and its preparation method are the same as those in embodiment 1.

[0068] Example 9

[0069] This embodiment provides a super slow-setting concrete.

[0070] The difference between this embodiment and embodiment 1 is that sodium gluconate, potassium sodium tartrate and methyl cellulose (viscosity of 350-550 mPa.s) are mixed in a weight ratio of 9:1:0.5, and then 11 g is weighed as a retarder; the other components of the super-slow setting concrete and its preparation method are the same as those in embodiment 1.

[0071] Example 10

[0072] This embodiment provides a super slow-setting concrete.

[0073] The difference between this embodiment and embodiment 1 is that sodium gluconate and potassium sodium tartrate are mixed in a weight ratio of 8:2, and then 11 g is weighed as a retarder; the other components of the super-slow setting concrete and its preparation method are the same as those in embodiment 1.

[0074] Embodiment 11

[0075] This embodiment provides a super slow-setting concrete.

[0076] The difference between this embodiment and embodiment 1 is that sodium gluconate, potassium sodium tartrate and methyl cellulose (viscosity of 350-550 mPa.s) are mixed in a weight ratio of 6:1:0.5, and then 11 g is weighed as a retarder; the other components of the super-slow setting concrete and its preparation method are the same as those in embodiment 1.

[0077] Example 12

[0078] This embodiment provides a super slow-setting concrete.

[0079] The difference between this embodiment and embodiment 1 is that the viscosity of methyl cellulose is 25 mPa.s; the other components of the super slow setting concrete and the preparation method thereof are the same as those in the embodiment.

[0080] Embodiment 13

[0081] This embodiment provides a super slow-setting concrete.

[0082] The difference between this embodiment and embodiment 1 is that the viscosity of methyl cellulose is 4000 mPa.s; the other components of the super slow setting concrete and the preparation method thereof are the same as those in embodiment 1.

[0083] Embodiment 14

[0084] This embodiment provides a super slow-setting concrete.

[0085] The difference between this embodiment and embodiment 1 is that the super slow setting concrete further comprises polysorbate 40 and polyethyleneimine (99%, molecular weight 10000) in a weight ratio of 3:4 as water retaining agents; the preparation method of the super slow setting concrete in this embodiment is:

[0086] According to the amount of each component in Table 1, cement, fly ash, slag powder, sand, crushed stone and 75wt% of the required water are mixed and stirred to obtain a primary mixed material;

[0087] Sodium gluconate, potassium sodium tartrate and methyl cellulose (viscosity 350-550 mPa.s) were mixed in a weight ratio of 8:2:1, and then 11 g was weighed as a retarder;

[0088] The HS-209 polycarboxylate water-reducing agent, retarder, water-retaining agent and the remaining water are mixed and stirred uniformly to obtain a premixed material; the premixed material is added to the primary mixed material and stirred to obtain a super-retarded concrete.

[0089] Embodiment 15

[0090] This embodiment provides a super slow-setting concrete.

[0091] The difference between this embodiment and embodiment 14 is that polysorbate 40 and polyethyleneimine (99%, molecular weight 10000) in a weight ratio of 1:4 are used as water retaining agents; the other components and preparation method of the super slow setting concrete in this embodiment are the same as those in embodiment 14.

[0092] Example 16

[0093] This embodiment provides a super slow-setting concrete.

[0094] The difference between this embodiment and embodiment 14 is that polysorbate 40 and polyethyleneimine (99%, molecular weight 10000) in a weight ratio of 3:2 are used as water retaining agents; the other components and preparation method of the super slow setting concrete in this embodiment are the same as those in embodiment 14.

[0095] Embodiment 17

[0096] This embodiment provides a super slow-setting concrete.

[0097] The difference between this embodiment and embodiment 14 is that polysorbate 40 and polyethyleneimine (99%, molecular weight 1800) in a weight ratio of 3:4 are used as water retaining agents; the other components and preparation method of the super slow setting concrete in this embodiment are the same as those in embodiment 14.

[0098] Embodiment 18

[0099] This embodiment provides a super slow-setting concrete.

[0100] The difference between this embodiment and embodiment 14 is that polysorbate 40 and polyethyleneimine (99%, molecular weight 20,000-30,000) are used as water retaining agents in a weight ratio of 3:4; the other components and preparation method of the super slow setting concrete in this embodiment are the same as those in embodiment 14.

[0101] Comparative Example

[0102] Comparative Examples 1-6

[0103] Comparative Examples 1-6 The comparative examples provide a super slow setting concrete.

[0104] The difference between the comparative example and Example 1 is that the amounts of the components in the super-slow setting concrete are different, as shown in Table 2; and the preparation method of the super-slow setting concrete is the same as that of Example 1.

[0105] Table 2 The dosage of each component in Comparative Examples 1-6

[0106]

[0107] Performance test The performance of the super slow setting concrete provided by Examples 1-18 and Comparative Examples 1-6 was tested, and the test method standard is as follows:

[0108] The initial setting time, final setting time, bleeding rate and slump at different times of super slow setting concrete are tested according to the methods specified in GB / T 50080 "Test methods for properties of ordinary concrete mixtures"; the compressive strength of super slow setting concrete is tested according to GB / T 50081 "Test methods for mechanical properties of ordinary concrete".

[0109] Test results: as shown in Table 3.

[0110] Table 3 Performance test results of super slow setting concrete provided by Examples 1-18 and Comparative Examples 1-6

[0111]

[0112]

[0113] Combined with Table 3, according to the test results of Examples 1-18 and Comparative Examples 1-6, it can be seen that the present application uses cement, fly ash, and slag powder in a suitable weight ratio as cementitious materials, and sand, crushed stone, water reducer, and retarder as raw materials for super-slow setting concrete. By controlling the amount of each raw material, the super-slow setting concrete prepared has a setting time of ≥62h, a water bleeding rate of ≤4.8%, a 20h slump of ≥165mm, and a 28d compressive strength of ≥49.5Mpa; while the performance of the super-slow setting concrete prepared in Comparative Examples 1-6 is poor. The test results show that the super-slow setting concrete provided by the present application has a longer setting time and a lower water bleeding rate, a better slump retention effect, and can quickly restore its strength growth after final setting, and has a higher 28d compressive strength.

[0114] By comparing the test results of Examples 1-3 with those of Comparative Examples 1-2, when cement, fly ash and slag powder in a weight ratio of (280-320): (70-90): (37-57) are selected as cementitious materials for preparing super-slow setting concrete, super-slow setting concrete with long setting time, low water bleeding rate and high slump in 20h can be obtained, and the super-slow setting concrete can quickly restore its strength growth after final setting, thereby having excellent compressive strength.

[0115] By comparing the test results of Example 1 with those of Comparative Examples 3-4, when the amount of the water reducer is less than 9 parts, the prepared super-slow setting concrete has a shorter setting time, a higher water bleeding rate (10.2%), and a lower compressive strength; when the amount of the water reducer is more than 13 parts, the prepared super-slow setting concrete has a shorter setting time and a lower compressive strength; and the present application controls the amount of the water reducer within the range of 9-13 parts, and when used to prepare the super-slow setting concrete, the super-slow setting concrete with a long setting time, a low water bleeding rate, and excellent compressive strength can be obtained.

[0116] By comparing the test results of Examples 1, 4-7, when only artificial sand or only natural sand is used, the performance of the super slow setting concrete is poor. Therefore, the present application selects artificial sand and natural sand for use in combination, and controls the weight ratio of the two to (400-460): (320-380), thereby obtaining super slow setting concrete with excellent performance.

[0117] By comparing the test results of Examples 1, 8-11 with Comparative Examples 5-6, when sodium gluconate, potassium sodium tartrate and methyl cellulose are used as retarders in a weight ratio of (7-9): (1-3): (0.5-1.5), and the amount of the retarder added is controlled within the range of 8-12 parts, a super-slow setting concrete with a long setting time, a low water bleeding rate, a high 20h slump and excellent compressive strength can be obtained.

[0118] Furthermore, by comparing the test results of Examples 1 and 12-13, when the viscosity of the methyl cellulose in the retarder is 25 mPa.s or 4000 mPa.s, the performance of the super-slow setting concrete is poor; while the present application selects methyl cellulose with a viscosity of 350-550 mPa.s in combination with sodium gluconate and sodium potassium tartrate as a retarder, and can obtain super-slow setting concrete with a long setting time, low water bleeding rate, high slump in 20h, and excellent compressive strength.

[0119] By comparing the test results of Examples 1 and 14-18, when polysorbate 40 and polyethyleneimine are added as water retaining agents in a weight ratio of (2-4):(3-5) to super slow setting concrete, the water bleeding rate of the super slow setting concrete can be further significantly reduced.

[0120] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A super slow setting concrete, characterized in that: The invention comprises the following components in parts by weight: 390-450 parts of cementitious material; 720-840 parts of sand; 920-1080 parts of crushed stone; 9-13 parts of water reducing agent; 8-12 parts of retarder; 150-200 parts of water; The cementitious material includes cement, fly ash and slag powder in a weight ratio of (280-320): (70-90): (37-57); The sand includes artificial sand and natural sand in a weight ratio of (400-460):(320-380); The retarder comprises sodium gluconate, sodium potassium tartrate and methyl cellulose in a weight ratio of (7-9): (1-3): (0.5-1.5); the viscosity of the methyl cellulose is 350-550 mPa.s.

2. The super slow setting concrete according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer.

3. The super slow setting concrete according to claim 1, characterized in that: The crushed stone is a continuously graded crushed stone of 5-25 mm.

4. The super slow setting concrete according to claim 1, characterized in that: The super slow setting concrete also includes 5-8 parts by weight of a water retaining agent; the water retaining agent includes polysorbate 40 and polyethyleneimine.

5. The super slow setting concrete according to claim 4, characterized in that: The water retaining agent comprises polysorbate 40 and polyethyleneimine in a weight ratio of (2-4):(3-5).

6. The method for preparing the super slow setting concrete according to any one of claims 1 to 5, characterized in that: The specific steps include: The cement, the fly ash, the slag powder, the sand, the crushed stone and 70-80 wt % of the required water are mixed and stirred uniformly to obtain a primary mixed material; Mixing and stirring other raw material components and the remaining water to obtain a premixed material; The premixed material is added into the primary mixed material for stirring to obtain the super slow setting concrete.

Images