Low-shrinkage and light-weight ultra-high performance concrete and preparation method thereof

Abstract

The application relates to the technical field of building materials, and particularly discloses low-shrinkage and low-creep lightweight super-high-performance concrete and a preparation method thereof. The low-shrinkage and low-creep lightweight super-high-performance concrete comprises the following raw materials in parts by weight: modified mixed lightweight aggregate 20-30 parts, polyacrylic acid water absorption resin 6-8 parts, cement 24-36 parts, high-efficiency water reducing agent 0.5-1 part, mineral admixture 4-6 parts, mixing water 16-24 parts, natural fiber 5-8 parts and modified steel fiber 8-12 parts; the modified mixed lightweight aggregate is a mixture of modified ceramic sand and glass beads; and the preparation method of the low-shrinkage and low-creep lightweight super-high-performance concrete comprises the following steps: mixing the natural fiber and the modified steel fiber in the mixing water in advance, and then adding the remaining raw materials in sequence and stirring uniformly to obtain the low-shrinkage and low-creep lightweight super-high-performance concrete. The product can be used in prefabricated cement concrete products, power construction projects and the like, and has the advantages of small shrinkage and low creep and high compressive strength.

Description

Technical Field

[0001] This application relates to the field of building materials technology, and more specifically, to a low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete and its preparation method. Background Technology

[0002] With the continuous development of concrete science and technology and the increasing demand for high-strength and lightweight structures, ordinary concrete can no longer meet the stringent requirements in many applications. Against this backdrop, ultra-high performance concrete (UHVPC) has emerged as a new type of material. This type of concrete is prepared by replacing cement with mineral admixtures, optimizing particle bulk density, reducing the water-cement ratio, and adding steel fibers and admixtures, resulting in excellent flowability and superior mechanical properties. However, compared with ordinary concrete, UHVPC still has some unresolved drawbacks: the performance of UHVPC is influenced by complex factors related to raw materials, and the preparation process involves many types of materials in large quantities, which has a complex impact on its preparation process and performance. In particular, the large amount of cementitious materials and the low water-cement ratio may lead to insufficient hydration of the cementitious materials, resulting in greater early shrinkage and creep. This situation can negatively affect the durability and strength of UHVPC.

[0003] Therefore, how to improve the mechanical properties of ultra-high performance concrete while reducing its shrinkage and creep is an urgent problem to be solved. Summary of the Invention

[0004] To reduce the shrinkage and creep of ultra-high performance concrete, this application provides a low-shrinkage and creep lightweight ultra-high performance concrete and its preparation method.

[0005] In the first aspect, this application provides a low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete, employing the following technical solution:

[0006] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete comprises the following raw materials in parts by weight: 20-30 parts of modified mixed lightweight aggregate, 6-8 parts of polyacrylic acid superabsorbent resin, 24-36 parts of cement, 0.5-1 parts of high-efficiency water-reducing agent, 4-6 parts of mineral admixtures, 16-24 parts of mixing water, 5-8 parts of natural fiber, and 8-12 parts of modified steel fiber; wherein the modified mixed lightweight aggregate is a mixture of modified ceramic sand and glass microspheres.

[0007] By adopting the above technical solution, the density of lightweight aggregate is lower than that of aggregate in traditional concrete. Its inclusion in concrete can effectively reduce the weight of the concrete. Simultaneously, using lightweight aggregate as concrete aggregate, with its rough and porous surface, provides strong water absorption. Pre-wetting allows it to absorb and store moisture internally. As the concrete paste gradually hardens, the relative humidity in the concrete capillaries is lower than that inside the modified lightweight aggregate, causing the moisture in the lightweight aggregate to gradually migrate and release into the concrete, compensating for paste shrinkage and reducing the concrete shrinkage value. Adding mineral admixtures prevents the lightweight aggregate from floating and separating in the paste, causing segregation and affecting the final performance of the concrete.

[0008] Natural fibers and modified steel fibers are distributed in a three-dimensional random pattern within the concrete. During later shrinkage and creep, the fibers transfer the load through adhesion to the concrete interface, reducing the stress generated by creep and shrinkage. Polyacrylic acid superabsorbent polymer (PAP) reacts chemically with cement hydration products to form a gel with good elasticity. This gel fills the pores in the concrete, making it denser and increasing its compressive strength. Furthermore, it encapsulates the lightweight aggregate, improving its compatibility with other components in the concrete. Its good water absorption enhances the concrete's water retention capacity, reducing shrinkage and cracking. Simultaneously, the expansion and deformation caused by PAP absorbing water compensates for concrete shrinkage and reduces cracking.

[0009] Optionally, the modified ceramic sand is prepared by the following steps:

[0010] (1) Soak the clay in water for 0.5-1 hour, then remove it to allow the clay to be saturated and surface-dry for later use;

[0011] (2) The above saturated surface-dried ceramic sand is placed in a solution of silane coupling agent and organosiloxane to react. Sodium hydroxide is added dropwise to adjust the solution to alkaline. The reaction is stirred at 140-160℃ for 30-40 minutes. After filtering out the liquid, it is air-dried to obtain modified ceramic sand.

[0012] (3) Mix the modified ceramic sand and glass microspheres evenly to obtain the modified mixed lightweight aggregate.

[0013] By adopting the above technical solution, pre-wetting the ceramsite provides internal curing for the concrete. When the concrete is short of water in the later stages, the release of moisture from the ceramsite reduces the later shrinkage of the concrete. However, using lightweight aggregate instead of traditional aggregate has problems such as low strength, easy floating and separation, and uneven distribution of lightweight aggregate, which can easily lead to a decrease in concrete strength. Modification improves the strength of the ceramsite. Silane coupling agents enhance the activity of functional groups on the surface of the ceramsite, and organosiloxanes are grafted onto the surface of the lightweight aggregate, increasing the compatibility of the lightweight aggregate with other components in the concrete and improving the strength of the interfacial transition zone, thereby further improving the compressive strength of the concrete. Simultaneously, the introduction of organosilanes can form a soft protective layer on the concrete surface, further mitigating concrete creep and shrinkage.

[0014] Optionally, in step (2), the weight ratio of ceramic sand, silane coupling agent and organosiloxane added is 1:(0.6-0.8):(2-3).

[0015] By adopting the above technical solution, when the reaction ratio of ceramic sand, silane coupling agent and organosiloxane is 1:(0.6-0.8):(2-3), sufficient organosilane groups can be grafted onto the surface of ceramic sand to encapsulate the aggregate and form an elastic network structure. During concrete shrinkage and creep, stress is relieved and the generation of drying shrinkage cracks is alleviated.

[0016] Optionally, the modified ceramic sand has a continuous gradation of 1-3 mm, and the microspheres have a continuous gradation of 0.6-1 mm.

[0017] By adopting the above technical solutions, controlling the aggregate gradation and particle size in combination with cementitious materials, it is beneficial to reduce the porosity of concrete, increase the density of concrete, and improve the strength of concrete.

[0018] Optionally, the modified steel fiber is obtained by modification with water-based epoxy resin, and the modification steps are as follows:

[0019] a. Mix 3-5 parts of aminosilane coupling agent, 5-8 parts of alcohol and 20-30 parts of deionized water, adjust the pH to 4-5, add waterborne epoxy resin and continue stirring to obtain the modified solution;

[0020] b. Add the steel fibers to the above-mentioned modified liquid and continue stirring. Heat in a water bath at 50-60°C for 30 minutes and dry to obtain the modified steel fibers.

[0021] By adopting the above technical solution, a rough coating layer is formed on the surface of the steel fiber modified with waterborne epoxy resin. Under acidic conditions, the silane coupling agent strengthens the connection between the steel fiber and the epoxy resin by activating the active groups on the surface of the steel fiber. On the other hand, the -NH2 in the coupling agent molecule can open the epoxy group in the epoxy resin molecule and form a chemical bond with the opened epoxy group, further improving the bonding strength between the steel fiber and the epoxy resin.

[0022] Optionally, the high-efficiency water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 15%-20%.

[0023] By adopting the above technical solutions, polycarboxylate superplasticizers can significantly reduce the amount of water used in concrete mixing. Furthermore, polycarboxylate superplasticizers have good compatibility with concrete and can be fully mixed with concrete, helping to improve the interfacial bonding force of concrete, thereby increasing the strength of concrete and resisting concrete creep and shrinkage.

[0024] Optionally, the mixing water is tap water with sodium bicarbonate dissolved in it, and the weight ratio of sodium bicarbonate to water is 1:(15-20).

[0025] By adopting the above technical solution, sodium bicarbonate is dissolved in water and diluted for use as mixing water for concrete. The addition of sodium bicarbonate can promote the growth of crystals in cement, generating substances such as calcium carbonate and calcium silicate, increasing the early strength of cement, improving the density of concrete, and further improving the shrinkage resistance of concrete.

[0026] Secondly, this application provides a method for preparing low-shrinkage and creep lightweight ultra-high performance concrete, employing the following technical solution:

[0027] A method for preparing low-shrinkage and creep lightweight ultra-high performance concrete includes the following steps:

[0028] (1) Dissolve sodium bicarbonate in tap water to obtain mixed water for later use;

[0029] (2) Mix natural fibers with modified steel fibers, add half of the mixing water and stir evenly to obtain a mixture;

[0030] (3) Add the modified lightweight aggregate, cement, high-efficiency water-reducing agent, mineral admixture and polyacrylic acid water-absorbing resin to the mixture, add the other half of the mixing water and stir until uniformly mixed to obtain the low-shrinkage creep lightweight ultra-high performance concrete.

[0031] By adopting the above technical solution, natural fibers and modified steel fibers are premixed. The functional groups on the surface of the modified steel fibers can react with the natural fibers to generate chemical bonds, which connect the natural fibers and the modified steel fibers together, increasing the fiber strength and strengthening the bonding ability between the steel fibers and concrete. When subjected to external loads, the synergistic effect of the fibers strengthens the binding force on the inside of the concrete, thereby improving the compressive strength of the concrete.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. Since this application uses modified mixed lightweight aggregate to replace traditional aggregate, the weight of concrete is effectively reduced. At the same time, the lightweight aggregate, due to its porous structure, can store more water, which can compensate for the shrinkage of the paste in the later stage of concrete hardening and reduce the shrinkage value of concrete.

[0034] 2. In this application, it is preferred to use ceramsite sand modified with organosilane mixed with glass microspheres. The good gradation improves the compatibility of ceramsite sand with other raw materials. At the same time, organosilane reacts with other components in concrete, such as cement, mineral admixtures and polyacrylic acid water-absorbing resin, to form an elastic network structure, which offsets shrinkage stress and alleviates the creep and shrinkage of concrete. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the embodiments.

[0036] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0037] Example of raw material preparation

[0038] Preparation of modified mixed lightweight aggregate

[0039] Preparation Example 1

[0040] A modified mixed lightweight aggregate is prepared by the following steps:

[0041] (1) Take 20kg of ceramic sand, soak it in water for 1 hour, then take it out and let the ceramic sand be saturated and dry for later use;

[0042] (2) The above saturated surface-dried ceramic sand was placed in a solution of 15 kg γ-methacryloxypropyltrichlorosilane (silane coupling agent) and 30 kg dimethylsiloxane (organosiloxane) to react. Sodium hydroxide was added dropwise to adjust the solution to alkaline. The reaction was stirred at 140°C for 40 min. After filtering out the liquid, the surface was dried to obtain modified ceramic sand.

[0043] (3) Mix the modified ceramic sand with 10 kg of glass microspheres until uniform, and the modified mixed lightweight aggregate is obtained.

[0044] Preparation Example 2

[0045] A modified mixed lightweight aggregate is prepared by the following steps:

[0046] (1) Take 10kg of ceramic sand, soak it in water for 0.5h, then take it out and let the ceramic sand be saturated and surface dry for later use;

[0047] (2) The above saturated surface-dried ceramic sand was placed in a solution of 8 kg γ-methacryloxypropyltrichlorosilane (silane coupling agent) and 30 kg dimethylsiloxane (organosiloxane) to react. Sodium hydroxide was added dropwise to adjust the solution to alkaline. The reaction was stirred at 140°C for 40 min. After filtering out the liquid, the surface was dried to obtain modified ceramic sand.

[0048] (3) Mix the modified ceramic sand with 10 kg of glass microspheres until uniform, and the modified mixed lightweight aggregate is obtained.

[0049] Example 3

[0050] A modified mixed lightweight aggregate is prepared by the following steps:

[0051] (1) Take 20kg of ceramic sand, soak it in water for 1 hour, then take it out and let the ceramic sand be saturated and dry for later use;

[0052] (2) The above saturated surface-dried ceramic sand was placed in a solution of 14 kg γ-methacryloxypropyltrichlorosilane (silane coupling agent) and 50 kg dimethylsiloxane (organosiloxane) to react. Sodium hydroxide was added dropwise to adjust the solution to alkaline. The reaction was stirred at 160°C for 30 min. After filtering out the liquid, the surface was dried to obtain modified ceramic sand.

[0053] (3) Mix the modified ceramic sand with 10 kg of glass microspheres until uniform, and the modified mixed lightweight aggregate is obtained.

[0054] Preparation Example 4

[0055] A modified mixed lightweight aggregate differs from Preparation Example 1 in that the weight ratio of ceramic sand, silane coupling agent and organosiloxane added in this preparation example is 1:0.5:1.

[0056] Preparation Example 5

[0057] A modified mixed lightweight aggregate differs from Preparation Example 1 in that the weight ratio of ceramic sand, silane coupling agent and organosiloxane added in this preparation example is 1:1:4.

[0058] Preparation of modified steel fibers

[0059] Preparation Example 7

[0060] A modified steel fiber, prepared by the following steps:

[0061] a. Mix 3 kg of KH-550 (aminosilane coupling agent), 6.5 kg of alcohol and 20 kg of deionized water, adjust the pH to 4, add 12.5 kg of waterborne epoxy resin and continue stirring to obtain the modified solution.

[0062] b. Add 12 kg of steel fiber to the above modified liquid and continue stirring. Heat and stir in a water bath at 50°C for 30 min. After filtration and drying, the modified steel fiber is obtained.

[0063] Preparation Example 8

[0064] A modified steel fiber, prepared by the following steps:

[0065] a. Mix 4 kg of KH-550 (aminosilane coupling agent), 5 kg of alcohol and 25 kg of deionized water, adjust the pH to 5, add 15 kg of waterborne epoxy resin and continue stirring to obtain the modified solution.

[0066] b. Add 12 kg of steel fiber to the above modified liquid and continue stirring. Heat and stir in a water bath at 50°C for 30 min. After filtration and drying, the modified steel fiber is obtained.

[0067] Preparation Example 9

[0068] A modified steel fiber, prepared by the following steps:

[0069] a. Mix 5 kg of KH-550 (aminosilane coupling agent), 8 kg of alcohol and 30 kg of deionized water, adjust the pH to 4, add 10 kg of waterborne epoxy resin and continue stirring to obtain the modified solution.

[0070] b. Add 12 kg of steel fiber to the above modified liquid and continue stirring. Heat and stir in a water bath at 60°C for 30 min. After filtration and drying, the modified steel fiber is obtained.

[0071] Example

[0072] Example 1

[0073] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete is prepared by the following steps:

[0074] (1) Dissolve 0.8 kg of sodium bicarbonate in 16 kg of water to obtain mixed water, and set aside;

[0075] (2) Mix 5 kg of cotton and linen fiber (natural fiber) with 10 kg of modified steel fiber prepared in Preparation Example 7, add 8 kg of mixing water and stir evenly to obtain a mixture;

[0076] (3) Add 20 kg of the modified lightweight aggregate prepared in Example 1, 36 kg of cement, 0.5 kg of polycarboxylate superplasticizer, 5 kg of fly ash (mineral admixture), and 6 kg of polyacrylic acid water-absorbing resin to the mixture, add the remaining 8 kg of mixing water, and stir until uniform to obtain the low-shrinkage creep lightweight ultra-high performance concrete. The modified ceramsite sand has a continuous gradation of 1-3 mm, and the microspheres have a continuous gradation of 0.6-1 mm. The polycarboxylate superplasticizer is model DH-4005;

[0077] Example 2

[0078] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete is prepared by the following steps:

[0079] (1) Dissolve 1 kg of sodium bicarbonate in 20 kg of water to obtain mixed water for later use;

[0080] (2) Mix 6.5 kg of cotton and linen fiber (natural fiber) with 12 kg of modified steel fiber prepared in Preparation Example 8, add 10 kg of mixing water and stir evenly to obtain a mixture;

[0081] (3) Add 25 kg of the modified lightweight aggregate prepared in Preparation Example 2, 30 kg of cement, 1 kg of polycarboxylate superplasticizer, 6 kg of fly ash (mineral admixture), and 7 kg of polyacrylic acid superabsorbent resin to the mixture, add the remaining 10 kg of mixing water, and stir until uniform to obtain the low-shrinkage creep lightweight ultra-high performance concrete. The modified ceramsite sand has a continuous gradation of 1-3 mm, and the microspheres have a continuous gradation of 0.6-1 mm.

[0082] Example 3

[0083] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete is prepared by the following steps:

[0084] (1) Dissolve 1.2 kg of sodium bicarbonate in 24 kg of water to obtain mixed water, and set aside;

[0085] (2) Mix 8 kg of cotton and linen fiber (natural fiber) with 8 kg of modified steel fiber prepared in Preparation Example 9, add 12 kg of mixing water and stir evenly to obtain a mixture;

[0086] (3) Add 30 kg of the modified lightweight aggregate prepared in Preparation Example 3, 24 kg of cement, 0.75 kg of polycarboxylate superplasticizer, 4 kg of fly ash (mineral admixture), and 8 kg of polyacrylic acid superabsorbent resin to the mixture, add the remaining 12 kg of mixing water, and stir until uniform to obtain the low-shrinkage creep lightweight ultra-high performance concrete. The modified ceramsite sand has a continuous gradation of 1-3 mm, and the microspheres have a continuous gradation of 0.6-1 mm.

[0087] Example 4

[0088] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete differs from Example 1 in that the modified mixed lightweight aggregate used in this example was prepared in Example 4.

[0089] Example 5

[0090] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete differs from Example 1 in that the modified mixed lightweight aggregate used in this example is the one prepared in Example 5.

[0091] Example 6

[0092] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete differs from Example 1 in that the mixing water used in this example is tap water.

[0093] Comparative Example

[0094] Comparative Example 1

[0095] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete differs from Example 1 in that the ceramsite in the lightweight aggregate of this comparative example is unmodified.

[0096] Comparative Example 2

[0097] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete, which differs from Example 1 in that polyacrylic acid superabsorbent resin was not added in this comparative example.

[0098] Comparative Example 3

[0099] A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete differs from Example 1 in that the steel fibers added in this comparative example are unmodified.

[0100] Performance testing

[0101] Detection methods / test methods

[0102] According to the "Test Procedure for Hydraulic Concrete" SL352—2006 and the "Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete" GB / T50082—2009, concrete specimens cured in a standard curing room with wet curing [temperature (20±2)℃, humidity greater than 95%] were measured at various ages, and the drying shrinkage value and 90-day creep value were recorded and calculated.

[0103] Compressive strength: The 28-day compressive strength of concrete was tested according to the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" GB / T50081-2002.

[0104] Table 1 Test Results

[0105]

[0106] Combining Examples 1-3 and Comparative Example 1 with Table 1, it can be seen that the test data of Examples 1-3 are all superior to those of Comparative Example 1. This indicates that the modified ceramsite sand has good compatibility with other components in concrete, enhances the interfacial bonding force between aggregates and other raw materials, further improves the strength of the interfacial transition zone, and increases the compressive strength of concrete. Simultaneously, the introduction of organosilanes during the modification process can form a soft protective layer on the concrete surface, mitigating concrete shrinkage and creep.

[0107] Based on Examples 1-3 and Comparative Example 2, and referring to Table 1, it can be seen that the test data of Examples 1-3 are all superior to those of Comparative Example 2. This indicates that polyacrylic acid superabsorbent polymer (PAS) can form an elastic network structure with fibers and cement hydration products in concrete, helping to fill the internal pores of the concrete and improve its density and compressive strength. Simultaneously, its excellent water absorption capacity gives it a certain expansion and deformation capacity to compensate for the later shrinkage of the concrete, and it can also release the water stored inside, alleviating the drying shrinkage of the concrete.

[0108] Combining Examples 1-3 and Comparative Example 3 with Table 1, it can be seen that the test data of Examples 1-3 are all better than those of Comparative Example 3. This indicates that when the steel fibers are not modified, they have poor compatibility with concrete, which makes them easy to fall off the concrete under stress and thus cannot effectively transfer loads or prevent concrete shrinkage and creep.

[0109] Combining Examples 1 and 4-5 with Table 1, it can be seen that the test data of Example 1 are better than those of Examples 4-5. This indicates that when modifying ceramic sand, if the weight ratio of ceramic sand, silane coupling agent and organosiloxane is limited to 1:(0.6-0.8):(2-3), the ceramic sand can be grafted with sufficient organosilane groups. If the ratio is too small, the reaction will be insufficient, and if the ratio is too large, resources will be wasted. Therefore, when the ratio is limited to the above range, stress can be relieved and drying shrinkage can be alleviated during concrete shrinkage and creep.

[0110] Combining Examples 1 and 6 with Table 1, it can be seen that the test data of Example 1 are better than those of Example 6. The mixing water used in Example 1 is mixing water with added sodium bicarbonate. The sodium bicarbonate reacts with the hydration products of cement to further fill the pores, enhance the density of concrete, and improve compressive strength.

[0111] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete, characterized in that, The raw materials include the following parts by weight: 20-30 parts modified mixed lightweight aggregate, 6-8 parts polyacrylic acid water-absorbing resin, 24-36 parts cement, 0.5-1 part high-efficiency water-reducing agent, 4-6 parts mineral admixture, 16-24 parts mixing water, 5-8 parts natural fiber, and 8-12 parts modified steel fiber; wherein the modified mixed lightweight aggregate is a mixture of modified ceramic sand and glass microspheres; The modified mixed lightweight aggregate is prepared by the following steps: (1) Soak the clay in water for 0.5-1 hour, then remove it to ensure that the clay is saturated and surface-dry, and set it aside for later use; (2) The above saturated surface-dried ceramic sand is placed in a solution of silane coupling agent and organosiloxane to react. The solution is adjusted to alkaline. The reaction is stirred at 140-160℃ for 30-40 min. After filtering out the liquid, it is air-dried to obtain modified ceramic sand. (3) Mix the modified ceramic sand and glass microspheres evenly to obtain the modified mixed lightweight aggregate; The modified steel fiber is obtained by modification with water-based epoxy resin, and the modification steps are as follows: a. By weight, mix 3-5 parts of aminosilane coupling agent, 5-8 parts of alcohol and 20-30 parts of deionized water, adjust the pH to 4-5, add 10-15 parts of waterborne epoxy resin and continue stirring to obtain the modified solution. b. Add the steel fibers to the above-mentioned modified liquid and continue stirring. Heat in a water bath at 50-60°C for 30 minutes and dry to obtain the modified steel fibers.

2. The low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete according to claim 1, characterized in that: In step (2), the weight ratio of ceramic sand, silane coupling agent and organosiloxane added is 1:(0.6-0.8):(2-3).

3. The low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete according to claim 1, characterized in that: The modified ceramic sand has a continuous gradation of 1-3 mm, and the glass microspheres have a continuous gradation of 0.6-1 mm.

4. The low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete according to claim 1, characterized in that: The high-efficiency water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 15%-20%.

5. The low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete according to claim 1, characterized in that: The mixing water is tap water with sodium bicarbonate dissolved in it, and the weight ratio of sodium bicarbonate to water is 1:(15-20).

6. A method for preparing low-shrinkage, creep-resistant, lightweight, ultra-high-performance concrete as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Mix natural fibers with modified steel fibers, add half of the mixing water and stir evenly to obtain a mixture; (2) Add the modified lightweight aggregate, cement, high-efficiency water-reducing agent, mineral admixture and polyacrylic acid water-absorbing resin to the mixture, add the other half of the mixing water and stir until uniformly mixed to obtain the low-shrinkage creep lightweight ultra-high performance concrete.

Images