A mass concrete temperature control and compensation shrinkage method

Abstract

The application discloses a mass concrete temperature control and shrinkage compensation method, and belongs to the technical field of temperature control and crack control in concrete construction. The method is specifically as follows: a cold storage unit is prepared, and then the cold storage unit is uniformly added into a concrete base material according to the volume of the concrete base material; the cold storage unit contains organic microcapsules with thermal expansion and cold contraction characteristics. The application ingeniously utilizes the phase change characteristics of the rapid freezing concrete cold storage unit to control temperature, utilizes the deformation characteristics of the capsule material thermal expansion and cold contraction to compensate shrinkage, and the size and shape of the cold storage unit can be designed according to a steel reinforcement cage, so that a novel technical scheme is provided for mass concrete temperature control and crack control, and the problems of complex equipment arrangement structure, high operation cost, difficult wastewater treatment and complex operation of the existing method can be effectively solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of temperature control and crack control in concrete construction, and particularly relates to a mass concrete temperature control and shrinkage compensation method. BACKGROUND

[0002] With the rapid development of large concrete structure projects such as hydraulic structures, bridges, super high-rise buildings, mass concrete structures are widely used, and temperature and cracking control of mass concrete is a major engineering problem. In order to prevent temperature cracks caused by excessive internal and external temperature difference due to early hydration heat of concrete, many cooling technologies have been applied in practical engineering, such as concrete surface maintenance technology, aggregate cooling technology, cooling water pipe technology, etc.

[0003] The concrete surface maintenance technology refers to covering plastic film, maintenance paper, etc. on the surface of the concrete after pouring, and supplementing water to the concrete and preventing water loss by regular watering. The traditional concrete surface maintenance technology involves a covering method that requires a lot of manpower and resources. Due to human negligence, watering and covering maintenance are usually not timely according to the requirements and time limits of the relevant national standards, and cannot meet the natural maintenance standards. The effect is only on the surface of the concrete, and the internal temperature control of the concrete cannot be achieved.

[0004] The aggregate cooling technology refers to cooling the coarse aggregate in the concrete composition material by water cooling or air cooling to reduce the pouring temperature of the concrete. Although the aggregate cooling technology can well control the temperature of the concrete through pre-cooling technology, it has complex pre-cooling process, multiple equipment layout, high operation cost, large cooling capacity loss, and problems such as large cooling aggregate area, difficult waste water treatment, and secondary cooling freezing, etc., which cannot meet the demand of high strength production.

[0005] The cooling water pipe technology refers to pre-embedding water pipes in the concrete, and when the hydration heat of the concrete reaches the peak value, the water pipes are used to transport cooling water to remove heat, achieving the effect of reducing the temperature of the concrete. Although the cooling water pipe technology can well reduce the internal temperature of the concrete, it introduces a large number of water pipes, which not only has a complex construction process, but also affects the mechanical properties of the concrete. In addition, due to the large number of joints between the water pipes and the complex cross construction process, the connection between the water pipes often fails, causing the cooling water pipe technology to fail to achieve the expected effect and affecting the quality of the concrete pouring.

[0006] In addition, mass concrete will shrink and crack due to hydration reaction, and often uses CaO, MgO and other expansion agents to supplement the shrinkage of concrete through chemical reaction. However, the introduction of chemical reaction will also produce additional hydration heat. Therefore, the control of hydration heat and shrinkage of mass concrete has always been a contradiction and a difficulty in engineering construction.

[0007] Therefore, in order to effectively reduce the internal temperature of mass concrete and avoid temperature cracks caused by excessive temperature difference between the inside and outside of the structure, a fast and effective, stable and reliable technical solution is urgently needed to realize internal temperature control during the construction of mass concrete. SUMMARY

[0008] In view of the above problems in the prior art, the present application provides a mass concrete temperature control and shrinkage compensation method, which ingeniously utilizes the phase change characteristics of the rapid freezing concrete cold storage unit for temperature control, utilizes the deformation characteristics of the thermal expansion and cold contraction of the capsule material for shrinkage compensation, and the size and shape of the cold storage unit can be designed according to the reinforcement cage, thereby providing a new technical solution for mass concrete temperature control and crack control.

[0009] To achieve the above object, the technical solution adopted by the present application to solve its technical problems is:

[0010] A mass concrete temperature control and shrinkage compensation method, a cold storage unit is prepared, and then the cold storage unit is uniformly added to the concrete base material according to the volume of the concrete base material.

[0011] The cold storage unit contains organic microcapsules having thermal expansion and cold contraction characteristics.

[0012] In the above scheme, the cold storage unit contains water and organic microcapsules having thermal expansion and cold contraction characteristics. The water has a relatively low temperature after being frozen and can be directly used to absorb the heat in the concrete base material, thereby achieving preliminary regulation of the temperature of the concrete. The organic microcapsules in the cold storage unit undergo phase change at a relatively high temperature and can further absorb heat from the concrete. The combination of the two achieves the purpose of temperature regulation of the concrete. Moreover, the organic microcapsules do not have a hydration reaction with cement and do not affect the performance of the concrete.

[0013] The organic microcapsules have the characteristics of thermal expansion and cold contraction. When they are inside the cold storage unit, they shrink. When they are added to the concrete, the high temperature environment causes them to expand, increasing the volume of the microcapsules. The cold storage unit in the concrete first shrinks after being frozen and then expands by absorbing heat, filling the internal pores and achieving shrinkage compensation of the mass concrete, thereby reducing the risk of cracking.

[0014] Further, the cold storage unit is a frozen concrete block prepared by freezing the concrete containing organic microcapsules at the initial stage of the hydration reaction.

[0015] In the above scheme, the organic microcapsules are first subjected to freezing treatment, and then added to the concrete, and subjected to rapid freezing treatment at the initial hydration stage of the concrete. The rapid cooling process can inhibit the hydration of cement. The unhydrated cement is made into a cold storage unit. When the cold storage unit is used, the temperature in the cold storage unit rises, and the cement in the cold storage unit continues to hydrate, without affecting the working performance of the cement.

[0016] Further, the temperature of the cold storage unit is -100℃ to -40℃.

[0017] In the above scheme, the temperature of the cold storage unit can be adjusted according to the engineering requirements to improve the cooling effect of the concrete. The specific temperature can be controlled by the consumption of liquid nitrogen.

[0018] Further, the mass of the organic microcapsules in the cold storage unit accounts for 1-5% of the mass of the cementitious materials in the cold storage unit.

[0019] In the above scheme, the proportion of the organic microcapsules is controlled to be 1-5%, which has an influence on the strength of the concrete of less than 10%, without affecting the working performance of the concrete.

[0020] Further, the shell material of the organic microcapsules is urea-formaldehyde resin, and the core material is epoxy resin.

[0021] In the above scheme, the organic microcapsules are prepared by in-situ polymerization, have the characteristics of thermal expansion and cold shrinkage, and do not have hydration reaction with cement. In the initial stage of concrete preparation, the organic microcapsules can fill the pores in the concrete, compensate for the shrinkage of the concrete to a certain extent, and increase the crack resistance of the concrete. When the crack is large, the shell is broken, and the core is released. The core acts as a repair agent to form a crystal at the crack, which can repair the cracked gap.

[0022] Further, the mass ratio of the shell and the core of the organic microcapsules is 1-1.2:1.

[0023] Further, the particle size of the organic microcapsules is 200-250μm.

[0024] Further, the shape of the cold storage unit includes one of a flat plate, a sphere, a column, and a block.

[0025] In the above scheme, the volume and shape of the cold storage unit can be designed according to the volume of the concrete. When used, the cold storage unit is uniformly dispersed in the concrete. Generally, the thickness of the layer in the construction and pouring process of the mass concrete should not be less than 20cm and not more than 50cm, and the design height of the cold storage unit should not be greater than the maximum layer pouring thickness specified in the construction scheme.

[0026] Further, the amount of the cold storage unit can be adjusted according to the engineering structure, and through finite element software analysis, the temperature control index that the temperature difference between the inside and the surface of the concrete should not be greater than 25 DEG C in the Standard for Construction Technology of Mass Concrete can be met.

[0027] The beneficial effects generated by the present application are:

[0028] In the process of pouring the mass concrete, the present application puts the concrete cold storage unit which is frozen rapidly, forms the mass concrete containing the designed cold storage unit, and realizes the temperature control of the mass concrete; meanwhile, the capsule material which expands when heated and shrinks when cooled is arranged in the cold storage unit, and the shrinkage control of the mass concrete is realized. The beneficial effects are as follows:

[0029] 1. The cold storage unit is prepared in the initial stage of the hydration reaction of the concrete, realizes the increase of the environmental temperature, and does not lose the strength after the hydration is sufficient.

[0030] 2. The cold storage unit contains water, can absorb heat in the phase change between -100 DEG C and 0 DEG C, and realizes the preliminary temperature control.

[0031] 3. The cold storage unit contains the organic microcapsule, the core of the organic microcapsule generally adopts the epoxy resin, can absorb heat in the phase change between 5 DEG C and 15 DEG C, and realizes the further temperature control.

[0032] 4. The cold storage unit contains the organic microcapsule, the capsule shrinks when the cold storage unit is prepared, expands in volume after absorbing heat and increasing temperature when put into the concrete, and realizes the shrinkage deformation compensation of the mass concrete.

[0033] 5. If the concrete does not crack, the epoxy resin is sealed in the organic microcapsule and does not affect the performance of the concrete by the hydration reaction with the cement; if cracks occur, the epoxy resin flows out, has the hydration reaction with the cement, and repairs the cracks.

[0034] 6. The block of the cold storage unit can be customized in the temperature, size and shape based on the engineering structure, the core area and the surface temperature difference requirement, and according to the steel reinforcement cage.

[0035] 7. The large finite element analysis software is used to analyze the feasibility and rationality according to the engineering structure size and the construction pouring scheme, evaluate the temperature control effect of the mass concrete containing the cold storage unit, optimize the design scheme of the cold storage unit, and realize the high efficiency and low energy consumption of the pouring scheme. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The process operation flowchart of the present application is shown in the figure;

[0037] Figure 2 The distribution diagram of the cold storage unit and the distribution nephogram of the influence on the internal temperature of the concrete are shown in the figure;

[0038] Figure 3 Statistical chart of the influence of different cold storage units on the temperature of the concrete bottom and surface;

[0039] Figure 4 Statistical chart of the temperature change trend of the concrete;

[0040] Figure 5 Statistical chart of the temperature change trend of the concrete;

[0041] Figure 6 Statistical chart of the volume compensation effect of the concrete mixed with different proportions of organic phase change materials. DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application, i.e., the described embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0043] Therefore, the detailed description of the embodiments of the present application provided below is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0044] It should be noted that the relational terms such as "first" and "second" and the like are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a list of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or apparatus. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0045] The features and performances of the present application will be further described in detail below with reference to the embodiments and the accompanying drawings.

[0046] Example 1

[0047] A mass concrete temperature control and shrinkage compensation method, comprising the following steps:

[0048] (1) The engineering project is a large C50 concrete foundation, the structure is 15m long, 20m wide, and 2m high;

[0049] (2) The initial temperature of the cold storage unit is set to -30℃, and the design size is 15cm long, 15cm wide, and 60cm high;

[0050] (3) The concrete containing organic microcapsules is frozen at the initial stage of hydration reaction to obtain a frozen concrete block, which is the cold storage unit; the content of organic microcapsules in the cold storage unit is 3% of the mass of the concrete cementitious material; the shell of the organic microcapsules is urea-formaldehyde resin, the core is epoxy resin, the mass ratio of the shell to the core is 1.2:1, and the particle size of the organic microcapsules is 250μm;

[0051] (4) The concrete is prepared according to the designed mixing proportion and is stirred uniformly; the shape of the prefabricated mold is designed, a part of the concrete and the already frozen organic microcapsules are mixed uniformly, and then the cold storage unit is prepared by a rapid freezing equipment;

[0052] (5) According to the construction scheme, the cold storage units are placed in layers, and the placement is densified near the center point area of the first layer considering that the bottom concrete has no air convection and slow heat dissipation;

[0053] (6) After the first layer of the foundation pit is poured, the concrete and the cold storage units are placed in turn according to the layer pouring direction, and the amount of the cold storage units is added according to the requirement that the temperature difference between the inner and surface of the mass concrete is less than 25℃;

[0054] (7) The temperature of the concrete in the above experimental example is analyzed by using a finite element analysis software.

[0055] Example 2

[0056] A mass concrete temperature control and shrinkage compensation method, comprising the following steps:

[0057] (1) The engineering project is a large C50 concrete foundation, the structure is 15m long, 20m wide, and 2m high;

[0058] (2) The initial temperature of the cold storage unit is set to -30℃, and the design size is 15cm long, 15cm wide, and 60cm high;

[0059] (3) The concrete containing organic microcapsules is frozen at the initial stage of hydration reaction to obtain a frozen concrete block, which is the cold storage unit; the content of organic microcapsules in the cold storage unit is 3% of the mass of the concrete cementitious material; the shell of the organic microcapsules is urea-formaldehyde resin, the core is epoxy resin, the mass ratio of the shell to the core is 1.2:1, and the particle size of the organic microcapsules is 250μm;

[0060] (4) Design the concrete mix proportion to prepare the concrete and mix it uniformly; design the shape of the prefabricated mold, mix a part of the concrete and the already pre-frozen organic microcapsules, and then prepare the cold storage unit through the rapid freezing equipment;

[0061] (5) According to the construction scheme, the cold storage units are placed in layers, considering that the bottom concrete has no air convection and slow heat dissipation, and the first layer of the center point area is arranged densely;

[0062] (6) After the first layer of the foundation pit is poured, the concrete and the cold storage unit are sequentially placed according to the layer pouring direction, and the added amount of the cold storage unit is determined according to the temperature difference between the inside and the surface of the mass concrete being less than 25℃;

[0063] (7) The concrete temperature of the above experimental example is analyzed by using the finite element analysis software.

[0064] Example 3

[0065] A mass concrete temperature control and shrinkage compensation method, comprising the following steps:

[0066] (1) The engineering project is a large C50 concrete foundation with a structure length of 15m, a width of 20m, and a height of 2m;

[0067] (2) The initial temperature of the cold storage unit is set to -60℃, and the design size is 15cm long, 15cm wide, and 15cm high;

[0068] (3) The concrete containing organic microcapsules is frozen at the initial stage of hydration reaction to obtain a frozen concrete block, which is the cold storage unit; the content of organic microcapsules in the cold storage unit is 3% of the mass of the cementitious material of the concrete; the shell of the organic microcapsules is urea-formaldehyde resin, the core is epoxy resin, the mass ratio of the shell to the core is 1.2:1, and the particle size of the organic microcapsules is 250μm;

[0069] (4) Design the concrete mix proportion to prepare the concrete and mix it uniformly; design the shape of the prefabricated mold, mix a part of the concrete and the already pre-frozen organic microcapsules, and then prepare the cold storage unit through the rapid freezing equipment;

[0070] (5) According to the construction scheme, the cold storage units are placed in layers, considering that the bottom concrete has no air convection and slow heat dissipation, and the first layer of the center point area is arranged densely;

[0071] (6) After the first layer of the foundation pit is poured, the concrete and the cold storage unit are sequentially placed according to the layer pouring direction, and the added amount of the cold storage unit is determined according to the temperature difference between the inside and the surface of the mass concrete being less than 25℃;

[0072] (7) The concrete temperature of the above experimental example is analyzed by using the finite element analysis software.

[0073] Example 4

[0074] A mass concrete temperature control and shrinkage compensation method, comprising the following steps:

[0075] (1) The engineering project is a large C50 concrete foundation, with a structure length of 15 m, a width of 20 m, and a height of 2 m;

[0076] (2) The initial temperature of the cold storage unit is set to -60 DEG C, and the design size is 15 cm long, 15 cm wide, and 15 cm high;

[0077] (3) The concrete containing organic microcapsules is frozen at the initial stage of hydration reaction to obtain a frozen concrete block, which is the cold storage unit; the content of organic microcapsules in the cold storage unit is 5% of the mass of the cementitious material of the concrete; the shell of the organic microcapsules is urea-formaldehyde resin, the core is epoxy resin, the mass ratio of the shell to the core is 1.2:1, and the particle size of the organic microcapsules is 250 μm;

[0078] (4) The concrete is prepared by designing the mixing proportion and stirring uniformly; the shape of the prefabricated mold is designed, a part of the concrete and the already pre-frozen organic microcapsules are mixed uniformly, and then the cold storage unit is prepared by a rapid freezing equipment;

[0079] (5) According to the construction scheme, the concrete is placed in layers, and considering that the bottom concrete has no air convection and slow heat dissipation, the encryption arrangement is carried out near the center point area of the first layer;

[0080] (6) After the first layer of the foundation pit is poured, the concrete and the cold storage unit are sequentially placed according to the layer pouring direction, and the added amount of the cold storage unit is less than 25 DEG C according to the inner and surface temperature difference of the mass concrete;

[0081] (7) The concrete temperature of the above experimental example is analyzed by using a finite element analysis software.

[0082] Comparative Example 1

[0083] A mass concrete construction cooling technology method using cooling water pipes, comprising the following steps:

[0084] (1) The engineering project is a large C50 concrete foundation, with a structure length of 15 m, a width of 20 m, and a height of 2 m;

[0085] (2) Four layers of cooling water pipes are arranged in the concrete, the outer diameter of the cooling water pipe is 48 mm, the wall thickness is 4 mm, the upper cooling water pipe is 0.5 m away from the surface, the lower cooling water pipe is 0.5 m away from the bottom, and the vertical direction distance between adjacent cooling water pipes is 1.0 m;

[0086] (3) Select the appropriate water source for water, water time from the cooling pipe covered with concrete layer by layer after the start; water time should not be too long, generally 5-6d; water velocity control at 16-20L / min, the water temperature of the inlet is 18-20℃;

[0087] (4) With the internal temperature of the concrete, the water temperature of the outlet also gradually increases, and the water flow should be increased accordingly. According to the temperature change of the concrete, the input amount and flow rate of the water should be adjusted to achieve the appropriate cooling effect;

[0088] (5) Then, the water flow should be gradually reduced until the water temperature of the outlet is basically the same as that of the inlet; the water temperature control mode of the inlet is mainly to add ice blocks to the water tank to reduce the water temperature to 20-24℃;

[0089] (6) Use finite element analysis software to analyze the temperature of the concrete of the above comparative example.

[0090] Comparative Example 2

[0091] A construction scheme without taking cooling measures, comprising the following steps:

[0092] (1) The engineering project is a large C50 concrete foundation, with a structure length of 15m, a width of 20m, and a height of 2m;

[0093] (2) The concrete is poured in a layered and continuous manner, with a layer thickness not less than 20cm and not more than 50cm; the continuous pouring of concrete is controlled, and the intermittent time should be before the initial setting of the previous layer of concrete; for more than 2h, it should be treated as a construction joint;

[0094] (3) After the concrete is poured, the local slurry leakage, drop (leakage) slag is wiped off in time before setting with a wet cloth, and the concrete adhered to the steel bar is also wiped off in time with the same method. Before the final setting of the concrete, the initial cracks (due to the settlement and dry shrinkage of the concrete) must be trimmed and flattened with an iron trowel, and then covered and maintained;

[0095] (4) No other insulation and cooling measures are taken.

[0096] (5) Use finite element analysis software to analyze the temperature of the concrete of the above comparative example.

[0097] Comparative Example 3

[0098] A mass concrete temperature control and shrinkage compensation method, comprising the following steps:

[0099] (1) The engineering project is a large C50 concrete foundation, with a structure length of 15m, a width of 20m, and a height of 2m;

[0100] (2) The initial temperature of the cold storage unit is set to -60℃, and the design dimensions are 15cm long, 15cm wide, and 15cm high.

[0101] (3) Design the concrete mix proportion, prepare the concrete, and mix it evenly; design the shape of the precast mold, and take a portion of the concrete to prepare a cold storage unit through a rapid freezing device;

[0102] (4) Layered placement is carried out according to the construction plan. Considering that the bottom concrete has no air convection and slow heat dissipation, the layer is densely arranged near the center point area of ​​the first layer.

[0103] (5) After the first layer of the foundation pit is poured, concrete and cold storage units are poured in sequence according to the pouring direction of each layer.

[0104] (6) The concrete temperature of the above experimental example was analyzed using finite element analysis software.

[0105] Experimental Example

[0106] The project, located on the foundation structure of a wastewater treatment plant in Chengdu, Sichuan Province, is a large-scale concrete pouring project. With its large structural dimensions and long pouring period, pouring in the high temperatures of summer can easily lead to excessive temperature differences between the inner and outer surfaces of the concrete structure, causing temperature cracks and reducing the structural durability. The technical solution described in this invention is applied to different areas of this project, and the concrete temperature is monitored in real time using pre-embedded temperature sensors to assess whether the temperature control requirements are met. The cooling effect of the technical solution described in this invention is analyzed. The specific process is as follows:

[0107] During implementation, the shrinkage value of concrete incorporating organic microcapsules was tested, and the internal and surface temperatures of the concrete were continuously monitored within the application area to evaluate the temperature control and cooling effects of different technical solutions. Cooling water pipe cooling technology and no cooling measures were used as a control group. The results are shown in [Table / Reference]. Figures 2 to 6 .

[0108] like Figures 2 to 5 As shown, the cold storage unit designed in Example 1 is a cube with dimensions of 15cm × 15cm × 15cm, and the cold storage unit designed in Example 2 is a cuboid with dimensions of 15cm × 15cm × 60cm. The temperature of both cold storage units is -30℃. Meanwhile, compared with Comparative Example 1, which uses cooling water pipes, and Comparative Example 2, which does not employ cooling measures, the bottom and surface temperatures of the concrete are both reduced to a certain extent, the temperature difference between the inside and the surface is controlled, and the internal temperature of the concrete is significantly controlled.

[0109] The surface temperature of the concrete in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 is similar, and the difference lies in the internal temperature. For Comparative Example 2 without temperature reduction measures, the temperature difference between the inside and surface of the concrete is 25℃, which has reached the temperature control requirement in the Standard for Construction Technology of Mass Concrete: the temperature difference between the inside and surface of the concrete should not be greater than 25℃. In the engineering implementation of Example 1, the internal temperature of the concrete can only be reduced by about 3℃, compared with the engineering implementation of Example 2, the bottom temperature of the concrete can be reduced by about 10℃, the surface temperature can be reduced by about 2℃, and the temperature difference between the inside and surface of the concrete is reduced from 25℃ to 16℃. It can be seen that the temperature control effect of Example 1 is slightly worse than that of Comparative Example 1 of the cooling water pipe cooling technology, but it has certain cooling effect and the advantage of simple and convenient operation without additional devices, and the temperature control effect of Example 2 is similar to that of the cooling water pipe technology. The technical scheme of Example 2 can effectively avoid the temperature cracks of the concrete caused by the excessive temperature difference between the inside and surface of the concrete, so that the temperature difference between the inside and surface of the concrete is controlled within the standard range.

[0110] As can be seen from the comparison of Example 3 and Example 4 with Example 2 and Comparative Example 2, the temperature of the cold storage unit and the content of the organic microcapsule have obvious influence on the cooling effect of the cold storage unit. It can be seen that after the temperature of the cold storage unit and the content of the organic phase change material are changed, the cooling effect on the overall temperature of the concrete continues to be enhanced. The organic phase change material will reach the reaction temperature (5-15℃) in about 20-24h, undergo phase change to absorb heat, and perform secondary temperature control. In the engineering implementation of Example 3 and Example 4, the bottom temperature of the concrete can be reduced by about 15℃, and the temperature difference between the inside and surface of the concrete is 12℃. Especially after the content of the organic microcapsule continues to increase, the temperature difference between the inside and surface of the concrete can be further reduced to 9℃, which is far lower than the temperature control index of 25℃ specified in the construction standard.

[0111] As shown in Table 1, the shrinkage of the concrete mixed with the organic microcapsule and the shrinkage of the concrete without the organic microcapsule are tested by taking the method in Example 3, Example 4 and Comparative Example 3 as an example. Figure 6 The shrinkage deformation of the concrete during pouring can be reduced by mixing the organic microcapsule, and the shrinkage rate of the concrete with 3% and 5% content is significantly lower than that of the control group with 0% content. The 90d shrinkage rate of the concrete with 3% and 5% content is 7.81% and 7.17% respectively, which is decreased by 23.6% and 29.8% respectively compared with the 90d shrinkage rate of the control group with 0% content. The hydration process of the concrete mixed with the cold storage unit containing the organic phase change material is expanded by heat, thereby producing volume expansion and compensating the shrinkage of the concrete, which can effectively reduce the shrinkage deformation of the concrete in the hardening stage. Therefore, the content of the organic phase change material is scientifically controlled to effectively play the role of shrinkage compensation and avoid the cracking and damage of the concrete caused by excessive shrinkage.

[0112] In summary, through comparison, it can be seen that the technical scheme of the application can effectively alleviate the temperature rise inside the concrete, and realize mass concrete temperature control. Without introducing any harmful substances that change the water content and compactness of the mass concrete, the rapid freezing equipment forms a cold storage unit that can be designed according to the size and shape of the engineering structure, and cooling is realized by pouring during the pouring process, thereby providing a new technical scheme for mass concrete temperature control and crack control.

[0113] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical scheme of the application and are not limiting. Although the application has been described in detail with reference to examples, it should be understood by those skilled in the art that the technical scheme of the application can be modified or replaced by equivalents without departing from the spirit and scope of the technical scheme of the application, and all should be covered in the scope of the claims of the application.

Claims

1. A method for temperature control and shrinkage compensation in large-volume concrete, characterized in that, Prepare a cold storage unit, and then uniformly add the cold storage unit into the concrete substrate; The cold storage unit contains organic microcapsules with thermal expansion and contraction properties. The cold storage unit is prepared by freezing concrete containing organic microcapsules in the early stage of hydration reaction to obtain frozen concrete blocks. The preparation method is as follows: the organic microcapsules are first frozen, then added to the concrete, and then rapidly frozen together in the early stage of hydration. The temperature of the cold storage unit is -100℃ to -40℃. The mass of the organic microcapsules in the cold storage unit accounts for 1-5% of the mass of the cementitious materials in the cold storage unit. The shell material of the organic microcapsules is urea-formaldehyde resin, and the core material is epoxy resin.

2. The method for temperature control and shrinkage compensation of large-volume concrete as described in claim 1, characterized in that, The mass ratio of the capsule shell to the core in the organic microcapsule is 1-1.2:

1.

3. The method for temperature control and shrinkage compensation of large-volume concrete as described in claim 1, characterized in that, The organic microcapsules have a particle size of 200-250 μm.

4. The method for temperature control and shrinkage compensation of mass concrete as described in claim 1, characterized in that, The shape of the cold storage unit includes one of the following: flat plate, spherical, columnar, and block.

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