Large-volume shrinkage-compensating concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete, and particularly discloses large-volume shrinkage-compensating concrete and a preparation method thereof. The large-volume shrinkage-compensating concrete is prepared from the following components in parts by weight: 150 to 200 parts of cement, 40 to 80 parts of fly ash, 90 to 120 parts of mineral powder, 20 to 35 parts of an expanding agent, 700 to 900 parts of machine-made sand, 1000 to 1200 parts of broken stone, 5 to 9 parts of a water reducing agent, 3 to 5 parts of a hydration heat inhibitor and 140 to 180 parts of water, the hydration heat inhibitor comprises potato starch, sodium silicate, lauryl sodium sulfate, beta-cyclodextrin and ascorbic acid. The large-volume shrinkage-compensating concrete can effectively compensate shrinkage and reduce concrete cracks.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, and in particular to a large-volume shrinkage compensating concrete and a preparation method thereof. Background Art

[0002] In modern construction projects, large-volume concrete structures are increasingly used, such as large-scale foundation projects, high-rise buildings, water conservancy projects, etc. However, large-volume concrete has the technical problem of difficult-to-control hydration heat. In concrete, hydration heat is generated due to the heat released when cement reacts with water. This concentrated release of heat causes the temperature inside the concrete to rise, while the surface temperature is relatively low, resulting in a large temperature gradient. The existence of a temperature gradient will cause uneven shrinkage inside and outside the concrete, ultimately leading to the formation of cracks. Once cracks appear in a large-volume concrete structure, it will not only affect its overall performance and service life, but may also pose a safety hazard. Therefore, the development of a large-volume shrinkage compensating concrete that can effectively compensate for shrinkage and reduce cracks is of great significance to ensuring the quality and safety of construction projects. Summary of the invention

[0003] In order to obtain a large-volume shrinkage compensating concrete that can effectively compensate for shrinkage and reduce cracks, the present application provides a large-volume shrinkage compensating concrete and a preparation method thereof.

[0004] In the first aspect, the present application provides a large volume shrinkage compensating concrete adopting the following technical solution: A large volume shrinkage compensating concrete comprises the following components in parts by weight: 150-200 parts of cement, 40-80 parts of fly ash, 90-120 parts of mineral powder, 20-35 parts of expansion agent, 700-900 parts of machine-made sand, 1000-1200 parts of crushed stone, 5-9 parts of water reducer, 3-5 parts of hydration heat inhibitor, and 140-180 parts of water; the hydration heat inhibitor comprises potato starch, sodium silicate, sodium dodecyl sulfate, beta-cyclodextrin and ascorbic acid.

[0005] In the above technical scheme, the present application effectively reduces the hydration heat of mass concrete during the hardening process by adding a specific proportion of hydration heat inhibitor to mass concrete, reduces the temperature difference between the inside and outside of mass concrete, reduces the shrinkage and deformation of mass concrete, and reduces the possibility of cracking of mass concrete. Through the expansion effect of the expansive agent on mass concrete, the volume change of mass concrete caused by shrinkage is compensated, the internal stress of mass concrete is reduced, the shrinkage and deformation of mass concrete are further reduced, the volume of mass concrete is stabilized, the water consumption of mass concrete is reduced by the water reducer, and the hydration heat of mass concrete is further reduced. The present application effectively reduces the temperature difference between the inside and outside of mass concrete, effectively compensates for the volume shrinkage of mass concrete, and effectively prevents the generation of cracks in mass concrete through the interaction of hydration heat inhibitor, expansive agent and water reducer. At the same time, the hydration heat inhibitor of the present application can also significantly reduce the impact on the fluidity of large-volume concrete, significantly improve the working performance of large-volume concrete, and maintain the stability of the hydration reaction process by regulating the growth of hydration products of large-volume concrete, thereby extending the initial and final setting time difference of concrete, thereby facilitating the uniform development of the internal structure of large-volume concrete, helping to improve the microstructure of large-volume concrete, helping to reduce porosity and increase density, thereby enhancing the mechanical strength and anti-permeability of concrete.

[0006] Specifically, the reason why the hydration heat inhibitor can effectively reduce the hydration heat of mass concrete during the hydration process is that: potato starch has water absorption, heat absorption and gelling properties, can absorb hydration heat in time and continuously and slowly release water and participate in the hydration reaction; an appropriate amount of sodium silicate absorbs part of the free water in the mass concrete and forms a gel-like substance, filling the micropores of the mass concrete while reducing the intensity of the hydration reaction; sodium dodecyl sulfate disperses cement particles and reduces the cohesion of the mass concrete, and works with potato starch and β-cyclodextrin to form a thin film at the water-cementitious material interface, slowing down the precipitation and nucleation of hydration products, thereby reducing the hydration reaction rate and the hydration heat; ascorbic acid, as an organic acid, cooperates with potato starch, sodium silicate, sodium dodecyl sulfate and β-cyclodextrin to effectively reduce the generation of hydration heat, effectively reduce the generation of cracks and effectively improve the density by extending the difference between the initial and final setting time of concrete. The present application affects the hydration reaction rate and heat release at different levels through the synergistic effect of potato starch, sodium silicate, sodium dodecyl sulfate, β-cyclodextrin and ascorbic acid, reduces the impact on the fluidity of large-volume concrete, achieves effective control of the hydration heat of large-volume concrete, and ensures the fluidity of large-volume concrete.

[0007] Preferably, the hydration heat inhibitor comprises, based on the mass fraction of the hydration heat inhibitor, 20 to 40 parts of potato starch, 10 to 20 parts of sodium silicate, 10 to 20 parts of sodium lauryl sulfate, 10 to 20 parts of β-cyclodextrin and 8 to 15 parts of ascorbic acid.

[0008] In the above technical scheme, the present application further optimizes the performance of the hydration heat inhibitor by limiting the specific content of each raw material in the hydration heat inhibitor, making it more effective in reducing hydration heat, improving the working performance of large-volume concrete and improving the quality of large-volume concrete structures. The synergistic effect of potato starch, sodium silicate, sodium dodecyl sulfate, β-cyclodextrin and ascorbic acid can not only effectively reduce the hydration heat, but also improve the fluidity of large-volume concrete, extend the initial and final setting time difference, thereby facilitating the uniform development of the internal structure of large-volume concrete, reducing porosity, improving density, and enhancing the mechanical strength and anti-permeability of large-volume concrete.

[0009] Preferably, the hydration heat inhibitor comprises 35 parts of potato starch, 15 parts of sodium silicate, 12 parts of sodium lauryl sulfate, 15 parts of β-cyclodextrin and 12 parts of ascorbic acid.

[0010] In the above technical scheme, the present application ensures that the hydration heat inhibitor can play the best role in the preparation process of large-volume concrete by further optimizing the ratio of each raw material of the hydration heat inhibitor, thereby significantly reducing the hydration heat peak of the large-volume concrete and reducing the internal temperature gradient of the large-volume concrete, thereby effectively avoiding cracks caused by temperature stress.

[0011] Preferably, the preparation method of the hydration heat inhibitor comprises the following steps: Step s1: potato starch, sodium silicate, sodium dodecyl sulfate and water are mixed, heated to 80-90° C., and stirred evenly; Step s2: cooling to below 40° C., adding ascorbic acid and stirring evenly, and spray drying to obtain a hydration heat inhibitor.

[0012] Preferably, in step s2, the product is sieved through a 100-mesh sieve after spray drying.

[0013] In the above technical solution, the present application ensures the uniformity and stability of the hydration heat inhibitor through a specific preparation method, thereby ensuring that the hydration heat inhibitor plays a better role in concrete.

[0014] Preferably, the water reducer is a polycarboxylate water reducer. As a high-efficiency water reducer, polycarboxylate water reducer can effectively reduce the water-cement ratio of large-volume concrete, improve the fluidity of concrete, reduce the amount of cement, and further reduce the hydration heat.

[0015] Preferably, the expansion agent is one of calcium sulfoaluminate expansion agent and composite expansion agent. The addition of expansion agent can produce micro expansion inside the large volume concrete, compensate for the volume reduction caused by temperature change and shrinkage, and thus effectively prevent the generation of cracks.

[0016] Preferably, the large volume shrinkage compensating concrete further comprises 10 to 15 parts of aluminum silicate fibers.

[0017] In the above technical solution, the addition of aluminum silicate fiber can improve the tensile strength of concrete, enhance the crack resistance of large-volume concrete, and further improve the stability and durability of the structure. At the same time, aluminum silicate fiber also has good thermal conductivity. When added to large-volume shrinkage compensating concrete, it can interact with the hydration heat inhibitor to form a three-dimensional mesh heat dissipation structure in the large-volume concrete, optimize the heat conduction of the large-volume concrete at the microscopic level, disperse the heat inside the large-volume concrete, further effectively control the temperature of the large-volume concrete, and further reduce the occurrence of cracks in the large-volume concrete.

[0018] In the second aspect, the present application provides a method for preparing a large volume shrinkage compensating concrete using the following technical solution: A method for preparing large-volume shrinkage compensating concrete comprises the following steps: Step 1: Mix cement, fly ash, mineral powder and hydration heat inhibitor evenly to form a dry mix; mix machine-made sand and crushed stone evenly to form an aggregate mixture; mix water reducer and water evenly to form an aqueous solution; Step 2: Mix the aggregate mixture with the aqueous solution, stir evenly, then add the remaining raw materials and stir thoroughly until they are evenly mixed to obtain large-volume shrinkage-compensating concrete.

[0019] In the above technical solution, the present application first mixes cement, fly ash, mineral powder and hydration heat inhibitor to form a dry mix, which can ensure the uniform distribution of the hydration heat inhibitor in the concrete, so that it can play the best role in the hydration process. At the same time, the present application first mixes the aggregate mixture with the aqueous solution and then adds the remaining raw materials to ensure the uniformity and stability of the large-volume concrete, and further improve the shrinkage compensation and crack resistance of the large-volume shrinkage compensation concrete.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. This application effectively controls the hydration heat of mass concrete through the interaction of hydration heat inhibitor, expansion agent and water reducing agent, effectively compensates for the volume shrinkage of mass concrete, reduces the generation of cracks in mass concrete, and improves the density and mechanical properties of mass concrete; 2. The present application improves the working performance of large-volume concrete, prolongs the difference between initial and final setting time, and is beneficial to the uniform development of the internal structure of concrete, reduces porosity, and improves density through the synergistic effect of potato starch, sodium silicate, sodium dodecyl sulfate, β-cyclodextrin, and ascorbic acid as a hydration heat inhibitor.

[0021] 3. This application enhances the crack resistance of large-volume concrete by adding aluminum silicate fiber, improves the stability and durability of the structure, and at the same time optimizes heat conduction, disperses internal heat, and further reduces the occurrence of cracks. DETAILED DESCRIPTION

[0022] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0023] Preparation Example 1 A hydration heat inhibitor comprises 20 kg of potato starch, 20 kg of sodium silicate, 10 kg of sodium dodecyl sulfate, 20 kg of beta-cyclodextrin and 8 kg of ascorbic acid.

[0024] Among them, potato starch was purchased from Jinan Derun Food Ingredients Co., Ltd.

[0025] Among them, sodium silicate was purchased from Zhonghe New Materials (Dezhou) Co., Ltd., product name: instant sodium silicate.

[0026] Among them, sodium dodecyl sulfate was purchased from Jinan Daorong Chemical Co., Ltd., product model: dr-09.

[0027] Among them, β-cyclodextrin was purchased from Hubei Xinghengye Technology Co., Ltd., product model: industrial grade.

[0028] Among them, ascorbic acid was purchased from Shandong Yonglida New Material Technology Co., Ltd., product model: industrial grade.

[0029] The preparation method of the hydration heat inhibitor comprises the following steps: Step s1: Mix a mixture of potato starch, sodium silicate and sodium dodecyl sulfate with water in a volume ratio of 1:6, heat to 80° C., and stir evenly.

[0030] Step s2: cooling to below 40° C., adding ascorbic acid and stirring evenly, spray drying in a spray dryer, and passing through a 100-mesh sieve to obtain a hydration heat inhibitor.

[0031] Preparation Example 2 A hydration heat inhibitor, which is different from Preparation Example 1 in that it includes 40 kg of potato starch, 10 kg of sodium silicate, 20 kg of sodium lauryl sulfate, 10 kg of beta-cyclodextrin and 15 kg of ascorbic acid.

[0032] The preparation method of the hydration heat inhibitor comprises the following steps: Step s1: Mix a mixture of potato starch, sodium silicate and sodium dodecyl sulfate with water in a volume ratio of 1:8, heat to 90° C., and stir evenly.

[0033] Step s2: cooling to below 40° C., adding ascorbic acid and stirring evenly, spray drying in a spray dryer, and passing through a 100-mesh sieve to obtain a hydration heat inhibitor.

[0034] Preparation Example 3 A hydration heat inhibitor, which is different from Preparation Example 1 in that it comprises 35 kg of potato starch, 15 kg of sodium silicate, 12 kg of sodium dodecyl sulfate, 15 kg of beta-cyclodextrin and 12 kg of ascorbic acid.

[0035] The preparation method of the hydration heat inhibitor comprises the following steps: Step s1: Mix a mixture of potato starch, sodium silicate and sodium lauryl sulfate with water in a volume ratio of 1:7, heat to 85° C., and stir evenly.

[0036] Step s2: cooling to below 40° C., adding ascorbic acid and stirring evenly, spray drying in a spray dryer, and passing through a 100-mesh sieve to obtain a hydration heat inhibitor.

[0037] Comparative Preparation Example 1 A hydration heat inhibitor, which is different from Preparation Example 1 in that potato starch is replaced by wheat starch in equal amounts.

[0038] Comparative Preparation Example 2 A hydration heat inhibitor, which is different from Preparation Example 1 in that β-cyclodextrin is replaced by α-cyclodextrin in equal amounts.

[0039] Comparative Preparation Example 3 A hydration heat inhibitor, which is different from Preparation Example 1 in that an equal amount of sodium silicate is replaced by calcium silicate.

[0040] Comparative Preparation Example 4 A hydration heat inhibitor, which is different from Preparation Example 1 in that sodium dodecyl sulfate is replaced by polyoxyethylene octylphenol ether-10 in equal amounts.

[0041] Comparative Preparation Example 5 A hydration heat inhibitor, which is different from Preparation Example 1 in that ascorbic acid is replaced by citric acid in equal amounts.

[0042] Example 1 A large volume shrinkage compensating concrete comprises 150kg of cement, 40kg of fly ash, 90kg of mineral powder, 20kg of expansion agent, 700kg of machine-made sand, 1000kg of crushed stone, 5kg of water reducing agent, 3kg of hydration heat inhibitor and 140kg of water.

[0043] Among them, the cement is ordinary silicate PO42.5 cement, brand: Southern Cement.

[0044] Among them, the fly ash is secondary fly ash.

[0045] Among them, the mineral powder is S95 grade.

[0046] Among them, the fineness modulus of artificial sand is 2.8.

[0047] Among them, the crushed stone is a continuous grade crushed stone with a particle size of 5 to 25 mm.

[0048] Among them, the expansion agent is UEA expansion agent, which was purchased from Guangxi Nanning Gaohong Herun Building Materials Technology Co., Ltd.

[0049] Among them, the water reducer is a polycarboxylic acid type water reducer, which was purchased from Guangzhou Runhong Chemical Co., Ltd.

[0050] The hydration heat inhibitor comes from Preparation Example 1.

[0051] The method for preparing large-volume shrinkage compensating concrete comprises the following steps: Step 1: Mix cement, fly ash, mineral powder and hydration heat inhibitor evenly to form a dry mix; mix machine-made sand and crushed stone evenly to form an aggregate mixture; mix water reducer and water evenly to form an aqueous solution; Step 2: Mix the aggregate mixture with the aqueous solution, stir evenly, then add the remaining raw materials and stir thoroughly until they are evenly mixed to obtain large-volume shrinkage-compensating concrete.

[0052] Example 2 A large volume shrinkage compensating concrete, which is different from Example 1 in that it includes 200kg cement, 80kg fly ash, 120kg mineral powder, 35kg expansion agent, 900kg machine-made sand, 1200kg crushed stone, 9kg water reducer, 5kg hydration heat inhibitor, and 180kg water.

[0053] Among them, the hydration heat inhibitor comes from Preparation Example 2.

[0054] Example 3 A large volume shrinkage compensating concrete, which is different from Example 1 in that it includes 160kg cement, 50kg fly ash, 95kg mineral powder, 27kg expansion agent, 780kg machine-made sand, 1080kg crushed stone, 6.76kg water reducer, 3.4kg hydration heat inhibitor, and 150kg water.

[0055] Among them, the hydration heat inhibitor comes from Preparation Example 3.

[0056] Example 4 A large volume shrinkage compensating concrete, which is different from Example 3 in that it also includes 10 kg of aluminum silicate fiber.

[0057] Example 5 A large volume shrinkage compensating concrete, which is different from Example 3 in that it also includes 15 kg of aluminum silicate fiber.

[0058] Comparative Example 1 A large volume shrinkage compensating concrete, which is different from Example 1 in that the hydration heat inhibitor comes from Comparative Preparation Example 1.

[0059] Comparative Example 2 A large volume shrinkage compensating concrete, which is different from Example 1 in that the hydration heat inhibitor comes from Comparative Preparation Example 2.

[0060] Comparative Example 3 A large volume shrinkage compensating concrete, which is different from Example 1 in that the hydration heat inhibitor comes from Comparative Preparation Example 3.

[0061] Comparative Example 4 A large volume shrinkage compensating concrete, which is different from Example 1 in that the hydration heat inhibitor comes from Comparative Preparation Example 4.

[0062] Comparative Example 5 A large volume shrinkage compensating concrete, which is different from Example 1 in that the hydration heat inhibitor comes from Comparative Preparation Example 5.

[0063] Comparative Example 6 A large volume shrinkage compensating concrete, which is different from Example 1 in that it does not contain a hydration heat inhibitor.

[0064] Comparative Example 7 A large volume shrinkage compensating concrete, which is different from Example 1 in that it does not contain an expansion agent.

[0065] Performance Testing Refer to GB / T50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures" to test the slump, initial setting time, final setting time and adiabatic temperature rise of concrete; refer to GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete" to test the compressive strength of concrete at the 28th day; refer to GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" to measure the chloride ion penetration resistance of concrete at the 28th day using the electric flux method.

[0066] The above test results are shown in Table 1.

[0067] Table 1: Combined with the analysis of Table 1, it can be seen that the mass concrete of Examples 1 to 5 has good performance. Specifically, the mass concrete of Examples 1 to 5 has moderate slump, a large difference between the initial setting and final setting time, a high 28-day compressive strength, and good resistance to chloride ion penetration, which indicates that the mass concrete of Examples 1 to 5 has high density, good mechanical properties and workability.

[0068] Combined with the analysis of Example 1 and Comparative Examples 1 to 5, the hydration heat inhibitors of Comparative Examples 1 to 5 are inconsistent with Example 1, and the mass concrete of Example 1 and Comparative Examples 1 to 5 have differences in performance. It can be seen that the present application can improve the working performance of mass concrete, extend the difference between initial and final setting time, and improve the density of mass concrete through the synergistic effect of potato starch, sodium silicate, sodium dodecyl sulfate, β-cyclodextrin and ascorbic acid.

[0069] Combined with the analysis of Example 1, Example 4 and Example 5, aluminum silicate fiber is added in Example 4 and Example 5. It can be seen that further adding aluminum silicate fiber to the large-volume concrete of the present application can further improve the compressive strength of the large-volume concrete and reduce the occurrence of cracks, thereby improving the overall performance of the concrete.

[0070] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A large volume shrinkage compensating concrete, characterized in that: The invention comprises the following components in parts by weight: 150-200 parts of cement, 40-80 parts of fly ash, 90-120 parts of mineral powder, 20-35 parts of expansion agent, 700-900 parts of machine-made sand, 1000-1200 parts of crushed stone, 5-9 parts of water reducer, 3-5 parts of hydration heat inhibitor, and 140-180 parts of water; the hydration heat inhibitor comprises potato starch, sodium silicate, sodium dodecyl sulfate, β-cyclodextrin and ascorbic acid.

2. The large volume shrinkage compensating concrete according to claim 1, characterized in that: Calculated by weight of the hydration heat inhibitor, the hydration heat inhibitor comprises: 20 to 40 parts of potato starch, 10 to 20 parts of sodium silicate, 10 to 20 parts of sodium dodecyl sulfate, 10 to 20 parts of beta-cyclodextrin and 8 to 15 parts of ascorbic acid.

3. The large volume shrinkage compensating concrete according to claim 2, characterized in that: The hydration heat inhibitor comprises 35 parts of potato starch, 15 parts of sodium silicate, 12 parts of sodium lauryl sulfate, 15 parts of beta-cyclodextrin and 12 parts of ascorbic acid.

4. The large volume shrinkage compensating concrete according to claim 1, characterized in that: The preparation method of the hydration heat inhibitor comprises the following steps: Step s1: Mix potato starch, sodium silicate, sodium lauryl sulfate and water, heat to 80-90° C., and stir evenly; Step s2: cooling to below 40° C., adding ascorbic acid and stirring evenly, and spray drying to obtain a hydration heat inhibitor.

5. The large volume shrinkage compensating concrete according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer.

6. The large volume shrinkage compensating concrete according to claim 1, characterized in that: The expansion agent is one of a calcium sulfoaluminate expansion agent and a composite expansion agent.

7. The large volume shrinkage compensating concrete according to claim 1, characterized in that: The large volume shrinkage compensating concrete also includes 10 to 15 parts of aluminum silicate fibers.

8. A method for preparing a large volume shrinkage compensating concrete according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Mix cement, fly ash, mineral powder and hydration heat inhibitor evenly to form a dry mix; mix machine-made sand and crushed stone evenly to form an aggregate mixture; mix water reducer and water evenly to form an aqueous solution; Step 2: Mix the aggregate mixture with the aqueous solution, stir evenly, then add the remaining raw materials and stir thoroughly until they are evenly mixed to obtain large-volume shrinkage-compensating concrete.

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