A lightweight and highly ductile concrete and its preparation method

Abstract

The present invention relates to the technical field of concrete, and particularly relates to a lightweight and high-toughness concrete and a preparation method thereof, comprising the following raw materials in parts by weight: 43-45 parts of cement, 13-15 parts of fly ash, 11-12 parts of silica fume, 11-13 parts of water, 5-7 parts of shale ceramsite sand, 7-21 parts of shale ceramsite, 1-1.5 parts of water reducing agent, 0.05-0.07 parts of defoaming agent, 4.5-5.5 parts of steel fiber, and 0.12-0.16 parts of polypropylene fiber. By adding lightweight shale ceramsite, the present invention successfully reduces the bulk density of the concrete (reaching 1900 kg / m 3 ), and does not cause great changes in the performance of the concrete; at the same time, adding an appropriate amount of steel fiber solves the problem of large brittleness of traditional concrete and improves its toughness; and adding polypropylene fiber to the concrete successfully solves the problem of floating of lightweight aggregates and ensures the quality of the final product.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and particularly relates to a lightweight and high-toughness concrete and a preparation method thereof. Background Art

[0002] With the continuous reduction of available land area, the height of buildings has been continuously increased, and more and more defects of traditional concrete materials have been exposed. For example, traditional concrete has greater brittleness and is prone to cracking when subjected to tensile or impact loads. Once cracks appear, the crack propagation is rapid, affecting the safety and service life of the structure, and seriously affecting the development process of the construction industry.

[0003] Lightweight and high-toughness concrete is a new type of building material that combines the advantages of lightweight concrete and high-toughness materials. This kind of concrete not only has a lower density, thus reducing the self-weight of the structure, but also has higher toughness and durability, can effectively absorb energy while maintaining strength, and reduce the crack propagation.

[0004] At present, there have been some attempts to combine lightweight and high-toughness concrete products on the market, but there are still many problems in actual applications. For example, the mechanical properties of some lightweight and high-toughness concretes cannot meet the expectations, especially the balance between high strength and high toughness is difficult to achieve. Therefore, how to further improve its strength, toughness and durability while ensuring the lightweight of concrete is still a technical problem to be solved urgently.

[0005] During the production process of concrete, it is found that serious aggregate floating phenomenon occurs in lightweight aggregate concrete, and its own homogeneity is difficult to guarantee, which seriously affects the engineering quality. The main reason is that the lightweight aggregate used in lightweight concrete has a small bulk density and is easy to float in the concrete. How to effectively control the floating of lightweight aggregates in lightweight concrete is an important prerequisite for ensuring its engineering performance. Based on this, the present invention provides a lightweight and high-toughness concrete and a preparation method thereof. Summary of the Invention

[0006] Aiming at the defects of the prior art, the purpose of the present invention is to provide a lightweight and high-toughness concrete and a preparation method thereof to solve the problems put forward in the above background art.

[0007] The present invention adopts the following technical solutions to solve the technical problems:

[0008] The present invention provides a lightweight and high-toughness concrete, which comprises the following raw materials in parts by weight:

[0009] 43-45 parts of cement, 13-15 parts of fly ash, 11-12 parts of silica fume, 11-13 parts of water, 5-7 parts of shale sand, 7-21 parts of shale ceramsite, 1-1.5 parts of water reducer, 0.05-0.07 parts of defoamer, 4.5-5.5 parts of steel fiber, 0.12-0.16 parts of polypropylene fiber;

[0010] The polypropylene fiber is further modified, and the specific modification method is as follows:

[0011] Preheat the polypropylene fiber at 60-65℃ for 1 hour, stir the preheated polypropylene fiber in sufficient sulfuric acid solution, then wash with water, filter and dry;

[0012] Ultrasonic modification treatment is performed on the dried polypropylene fiber in a modification solution that is 3-5 times the total amount of the polypropylene fiber. After the ultrasonic modification is completed, the fiber is filtered and dried.

[0013] The modified liquid comprises the following raw materials in parts by weight: 2-5 parts by weight of 5% sodium silicate solution, 3-5 parts by weight of 2% dopamine hydrochloride solution, 5-8 parts by weight of boron nitride and 2-3 parts by weight of calcium titanate.

[0014] Preferably, the cement is 52.5 ordinary Portland cement;

[0015] The fly ash is first-grade fly ash;

[0016] The specific surface area of the silica fume is ≥19000m 2 / kg, of which SiO2 content is ≥90%.

[0017] Preferably, the shale ceramic sand is grade 900, with a bulk density of 900 kg / m 3 ~1400kg / m 3 It is composed of 0-5mm size, of which 0-3mm and 3-5mm shale ceramic sand account for 80% and 20% respectively. The cylinder pressure strength is greater than 4MPA, and the chemical composition is silicon dioxide, aluminum oxide, iron oxide, and calcium oxide.

[0018] The bulk density of shale ceramsite is 1000kg / m 3 ~1400kg / m 3 It is composed of 5-10mm in size and irregular polyhedron in shape. Its cylinder pressure strength is greater than 3MPA, its 24h water absorption rate is 9%, and its stacking porosity is greater than 26%.

[0019] Preferably, the water reducer is a polycarboxylate water reducer;

[0020] The main component of the defoamer is modified silicone;

[0021] The modified silicone was prepared by the prior art method of Example 1 in a graphene oxide modified silicone defoamer and its preparation method with the patent number 201710482754.9.

[0022] The steel fiber is a copper-plated fine straight steel fiber with a length of 12 mm and a diameter of 0.12 mm.

[0023] The polypropylene fiber is preheated and then acid-treated to optimize its activity efficiency. At the same time, it is improved and optimized by a modification liquid. The sodium silicate solution, 2% mass fraction of hydrochloric acid dopamine solution, boron nitride and calcium titanate in the modification liquid are mixed and blended. Through the coordination of raw materials, the polypropylene fiber is improved, thereby optimizing the performance improvement effect of the fiber in the system.

[0024] Preferably, the mass fraction of the sulfuric acid solution is 5 - 8%.

[0025] Preferably, the ultrasonic power of the ultrasonic modification treatment is 450 - 500 W, and the ultrasonic treatment is carried out for 1 h.

[0026] Preferably, the polypropylene fiber has a length of 12 mm, a diameter of 27 μm, and a tensile strength of 625 MPA.

[0027] The present invention also provides a preparation method of lightweight and high-toughness concrete, comprising the following steps: [[ID=१९]] [[ID=२०]]

[0028] [[ID=२१]]S1. Perform pre-wetting treatment on the shale ceramsite to obtain pre-wetted shale ceramsite; [[ID=२२]] [[ID=२३]]

[0029] [[ID=२४]]S2. Add the cement, fly ash and silica fume into a compulsory mixer and dry mix internally for 1 min to fully mix the raw materials and obtain a first mixture; [[ID=२५]] [[ID=२६]]

[0030] [[ID=२७]]S3. Mix water with a water reducer and a defoamer and stir evenly to obtain a second mixture, and then add the second mixture into the first mixture and continue to mix evenly to obtain mortar; [[ID=२८]] [[ID=२९]]

[0031] [[ID=३०]]Then add shale sand and pre-wetted shale ceramsite to the mortar in S3 and stir for 1 - 2 min so that the shale sand and pre-wetted shale ceramsite can be wrapped by the mortar; [[ID=३१]] [[ID=३२]]

[0032] [[ID=३३]]S4. Finally, add steel fiber and polypropylene fiber to the mixing equipment and stir fully for 1 - 2 min to form the concrete; [[ID=३४]] [[ID=३५]]

[0033] [[ID=३६]]S5. Mold the concrete in a mold and carry out moisture conservation maintenance. [[ID=३७]] [[ID=३८]]

[0034] [[ID=३९]]Compared with the prior art, the present invention has the following beneficial effects: [[ID=४०]] [[ID=४१]]

[0035] [[ID=४२]]By adding lightweight shale ceramsite, the present invention successfully reduces the bulk density of the concrete (reaching 1900 kg / m3 ), and it does not cause great changes in the performance of the concrete; at the same time, an appropriate amount of steel fiber is added to solve the problem of high brittleness of traditional concrete and improve its toughness; and polypropylene fiber is added to the concrete, successfully solving the problem of floating of lightweight aggregates and ensuring the quality of the final product.

[0036] For lightweight high-performance concrete, on the one hand, by adding lightweight components such as ceramsite and ceramic sand, the apparent density of the concrete is greatly reduced, achieving the purpose of lightweight high-performance concrete; at the same time, a reasonable ratio is used to make the lightweight aggregates evenly distributed in the concrete, so that the stress distribution is uniform; on the other hand, adding steel fibers to the matrix concrete can effectively inhibit the generation of macroscopic cracks in the concrete, and can improve the crack resistance, tensile strength, flexural strength, and impact resistance of the concrete, significantly enhancing the toughness of the lightweight concrete.

[0037] The main component of the defoamer described in the present invention is modified silicone, which can destroy the foam film and make the foam disappear quickly, so that the concrete surface is more compact and can effectively inhibit the generation of air bubbles in the concrete, greatly improving the crack resistance and abrasion resistance of the concrete.

[0038] The polypropylene fiber described in the present invention can successfully inhibit the floating of shale ceramsite. As a fine reinforcing material, the polypropylene fiber is added to the concrete or mortar containing lightweight aggregates. Through the three-dimensional network structure formed inside the mixture, the cohesion of the mixture is effectively increased. This enhanced cohesive property prevents the lightweight aggregate particles from migrating upward or floating to the surface, thus ensuring the uniform distribution of lightweight aggregates in the concrete or mortar and improving the quality and durability of the final product. Specific embodiments

[0039] The following combines specific embodiments to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0040] A kind of lightweight and high-toughness concrete in this embodiment includes the following raw materials in parts by weight:

[0041] 43 - 45 parts of cement, 13 - 15 parts of fly ash, 11 - 12 parts of silica fume, 11 - 13 parts of water, 5 - 7 parts of shale ceramic sand, 7 - 21 parts of shale ceramsite, 1 - 1.5 parts of water reducer, 0.05 - 0.07 parts of defoamer, 4.5 - 5.5 parts of steel fiber, 0.12 - 0.16 parts of polypropylene fiber.

[0042] The cement in this embodiment is ordinary Portland cement of 52.5;

[0043] The fly ash is first-grade fly ash;

[0044] The specific surface area of the silica fume is ≥19000m 2 / kg, of which SiO2 content is ≥90%.

[0045] The shale ceramic sand in this embodiment is grade 900, with a bulk density of 900 kg / m 3 ~1400kg / m 3 It is composed of 0-5mm size, of which 0-3mm and 3-5mm shale ceramic sand account for 80% and 20% respectively. The cylinder pressure strength is greater than 4MPA, and the chemical composition is silicon dioxide, aluminum oxide, iron oxide, and calcium oxide.

[0046] The bulk density of shale ceramsite is 1000kg / m 3 ~1400kg / m 3 It is composed of 5-10mm in size and irregular polyhedron in shape. Its cylinder pressure strength is greater than 3MPA, its 24h water absorption rate is 9%, and its stacking porosity is greater than 26%.

[0047] The water reducer in this embodiment is a polycarboxylate water reducer;

[0048] The main component of the defoamer is modified silicone;

[0049] The steel fiber is a copper-plated thin straight steel fiber with a length of 12 mm and a diameter of 0.12 mm.

[0050] The polypropylene fiber of this embodiment is further modified, and the specific modification method is as follows:

[0051] Preheat the polypropylene fiber at 60-65℃ for 1 hour, stir the preheated polypropylene fiber in sufficient sulfuric acid solution, then wash with water, filter and dry;

[0052] The dried polypropylene fiber is ultrasonically modified in a modification liquid with a volume 3-5 times the total volume of the polypropylene fiber. After the ultrasonic treatment is completed, the fiber is filtered and dried. The modification liquid comprises the following raw materials in parts by weight: 2-5 parts by mass of a 5% sodium silicate solution, 3-5 parts by mass of a 2% dopamine hydrochloride solution, 5-8 parts by mass of boron nitride and 2-3 parts by mass of calcium titanate.

[0053] The mass fraction of the sulfuric acid solution in this embodiment is 5-8%.

[0054] The ultrasonic modification treatment in this embodiment was performed at an ultrasonic power of 450-500 W and for 1 hour.

[0055] The polypropylene fiber of this embodiment has a length of 12 mm, a diameter of 27 μm, and a tensile strength of 625 MPa.

[0056] A preparation method of a lightweight and high-toughness concrete in this embodiment includes the following steps:

[0057] S1. Pre-wet the shale ceramsite to obtain pre-wetted shale ceramsite;

[0058] S2. Add the cement, fly ash and silica fume into a compulsory mixer and dry mix internally for 1 min to fully mix the raw materials and obtain a first mixture;

[0059] S3. Mix water with a water reducer and an antifoaming agent and stir evenly to obtain a second mixture, and then add the second mixture into the first mixture and continue to mix evenly to obtain mortar;

[0060] Then add shale ceramic sand and pre-wetted shale ceramsite into the mortar in S3 and stir for 1 - 2 min so that the shale ceramic sand and pre-wetted shale ceramsite can be wrapped by the mortar;

[0061] S4. Finally, add steel fiber and polypropylene fiber into the mixing equipment and stir fully for 1 - 2 min to form the concrete;

[0062] S5. Mold the concrete in a mold and conduct moisture conservation and curing.

[0063] Example 1, a lightweight and high-toughness concrete is prepared by mixing the following raw materials in parts by weight: 86 parts of cement, 26 parts of first-class fly ash, 22 parts of silica fume, 22 parts of water, 10 parts of shale ceramic sand, 14 parts of shale ceramsite, 3 parts of water reducer, 0.14 part of antifoaming agent, 11 parts of steel fiber, 0.32 part of polypropylene fiber.

[0064] Example 2, a lightweight and high-toughness concrete is prepared by mixing the following raw materials in parts by weight: 86 parts of cement, 26 parts of first-class fly ash, 22 parts of silica fume, 22 parts of water, 10 parts of shale ceramic sand, 28 parts of shale ceramsite, 3 parts of water reducer, 0.14 part of antifoaming agent, 11 parts of steel fiber, 0.32 part of polypropylene fiber.

[0065] Example 3, a lightweight and high-toughness concrete is prepared by mixing the following raw materials in parts by weight: 86 parts of cement, 26 parts of first-class fly ash, 22 parts of silica fume, 22 parts of water, 10 parts of shale ceramic sand, 42 parts of shale ceramsite, 3 parts of water reducer, 0.14 part of antifoaming agent, 11 parts of steel fiber, 0.32 part of polypropylene fiber.

[0066] In Example 1, Example 2, and Example 3, the cement is 52.5 ordinary Portland cement.

[0067] In Example 1, Example 2, and Example 3, the fly ash is first-class fly ash.

[0068] In Example 1, Example 2, and Example 3, the specific surface area of the silica fume ≥ 19000 m 2 / kg, where the SiO2 content ≥ 90%.

[0069] In Example 1, Example 2, and Example 3, the shale ceramsite sand is of grade 900, with a bulk density of 900 kg / m 3 ~1400 kg / m 3 , composed of 0 - 5 mm sizes, where the mass ratios of shale ceramsite sand of 0 - 3 mm and 3 - 5 mm are 80% and 20% respectively, the cylinder compressive strength is greater than 4 MPA, and the chemical components are mainly silica, alumina, iron oxide, and calcium oxide.

[0070] In Example 1, Example 2, and Example 3, the bulk density of the shale ceramsite is 1000 kg / m 3 ~1400 kg / m 3 , composed of 5 - 10 mm sizes, with an irregular polyhedron shape, the cylinder compressive strength is greater than 3 MPA, the 24 - hour water absorption rate is 9%, and the bulk porosity is greater than 26%.

[0071] In Example 1, Example 2, and Example 3, the water - reducing agent is a polycarboxylate water - reducing agent.

[0072] In Example 1, Example 2, and Example 3, the main component of the defoaming agent is modified silicone.

[0073] In Example 1, Example 2, and Example 3, the steel fiber is a copper - plated fine straight steel fiber, with a length of 12 mm and a diameter of 0.12 mm.

[0074] In Example 1, Example 2, and Example 3, the polypropylene fiber has a length of 12 mm, a diameter of 27 μm, and a tensile strength of 625 MPA.

[0075] In Example 1, Example 2, and Example 3, the difference between the examples lies in the volume ratios of the shale ceramsite in the lightweight high - toughness concrete, which are 10%, 20%, and 30% respectively.

[0076] The preparation method of the lightweight high - toughness concrete in Example 1, Example 2, and Example 3 is as follows:

[0077] S1. Perform pre - wetting treatment on the shale ceramsite to obtain pre - wetted shale ceramsite;

[0078] S2. Add the cement, fly ash, and silica fume into a compulsory mixer and dry - mix internally for 1 min, so that the raw materials are fully mixed to obtain a first mixture;

[0079] S3. The water and the water reducing agent, the defoaming agent were mixed and stirred to obtain a second mixture, and then the second mixture was added to the first mixture and continued to mix to obtain a mortar;

[0080] Then add shale sand and pre-wetted shale ceramsite to the mortar of S3 and stir for 2 minutes so that the shale sand and pre-wetted shale ceramsite can be wrapped by the mortar;

[0081] S4. Finally, add steel fiber and polypropylene fiber to the mixing equipment and stir thoroughly for 2 minutes to form the concrete;

[0082] S5. The concrete is formed in a mold and then maintained in a moisturizing condition.

[0083] The performance results are as follows:

[0084] The ultra-high performance concrete prepared in Examples 1-5 above was tested for its expansion, mechanical properties, and flexural toughness. The test standards and methods are as follows:

[0085] (1) Expansion test standard: refer to GB / T50080-2016 "Standard for test methods of performance of ordinary concrete mixtures".

[0086] (2) Compressive strength test standard: Refer to GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete" to make standard test blocks of 100mm×100mm×100mm, and test their compressive strength after 7d and 28d of curing.

[0087] (3) Bending toughness test standard: Referring to CECS13-2009 “Fiber Concrete Test Method Standard”, a 100mm×100mm×400mm beam specimen was made and a four-point bending test was performed to detect its bending toughness.

[0088] Here are the results:

[0089]

[0090] From the above results, it can be seen that the lightweight and high-toughness concrete prepared according to the present invention has higher mechanical properties, with an expansion of 555-615mm, a 7d compressive strength of 56.5-61.2MPA, and a 28d compressive strength of 69.9-78.9MPA; the flexural toughness ratio reaches 1.60-1.69.

[0091] It can be seen that the concrete of the present invention has high strength and good toughness, good durability and bearing capacity, and the apparent density of the concrete is reduced to 1845-1942 kg / m 3 .

[0092] As can be seen from the above results, with the increase of the volume ratio of shale ceramsite, the compressive strength of the concrete shows a gradually decreasing trend. This is because the strength of shale ceramsite itself is relatively low, which seriously affects the compressive strength of the concrete. At the same time, due to the light weight of shale ceramsite, with the increase of the volume ratio of shale ceramsite, the apparent density of the concrete also shows a gradually decreasing trend.

[0093] As can be seen from the above results, the wet ceramsite in the concrete can supplement water for the hydration of cement, making the hydration of cement paste more complete, and indirectly improving the mechanical properties of the concrete. When a defoaming agent is added to the concrete, the defoaming agent can control and reduce the bubbles generated during the mixing process of the concrete, thereby improving the performance of the concrete. Moreover, the surfactant in the defoaming agent can form a lubricating film in the concrete, enabling the concrete particles to slide relative to each other, thus improving the compactness of the concrete.

[0094] Comparative Example 1, a kind of ordinary steel fiber concrete is prepared by mixing the following raw materials in parts by weight: 18 parts of cement, 5 parts of fly ash, 7 parts of water, 25 parts of sand, 40 parts of crushed stone, 3 parts of steel fiber, and 0.3 parts of water reducing agent.

[0095] In Comparative Example 1, the cement is 42.5 ordinary Portland cement.

[0096] In Comparative Example 1, the fly ash is grade I fly ash.

[0097] In Comparative Example 1, the sand is high-quality natural river sand, with a fineness modulus of 2.60, belonging to the medium sand category, and having a continuous gradation.

[0098] In Comparative Example 1, the crushed stone is basalt crushed stone, composed of 5 - 25 mm in size, and having a continuous gradation.

[0099] In Comparative Example 1, the water reducing agent is polycarboxylate high-performance water reducing agent.

[0100] In Comparative Example 1, the steel fiber is end-hooked fiber, with a length of 35 mm, a diameter of 0.75 mm, and a tensile strength of 600 MPA.

[0101] The results are as follows:

[0102]

[0103] As can be seen from the above results, when comparing Example 1 with Comparative Example 1, the concrete of the present invention rationally selects raw materials, scientifically proportioned, and synergistically plays its role. The lightweight high-toughness concrete shows good toughness compared with ordinary steel fiber concrete and has better mechanical properties. This is because the addition of fine straight steel fibers forms a dense grid structure inside the lightweight concrete, inhibiting the generation and expansion of cracks, and greatly enhancing the toughness of the concrete.

[0104] And the addition of polypropylene fibers can, on the one hand, enhance the cohesion of concrete, prevent lightweight aggregate particles from migrating upward or floating to the surface, thus ensuring the uniform distribution of lightweight aggregates in concrete or mortar and improving the quality and durability of the final product; on the other hand, polypropylene fibers also play an important role in enhancing the toughness of concrete, which can effectively reduce the formation of microcracks in the early stage of concrete due to plastic shrinkage and temperature changes. At the same time, polypropylene fibers enhance the ability of concrete to resist sudden impacts or loads, can bridge the cracks that may form, thus delaying crack propagation and increasing the ability of the material to absorb impact energy. In summary, polypropylene fibers can provide additional support when stressed, increasing the flexural strength and toughness of the material.

[0105] Optimization Example 1: On the basis of Example 1, the polypropylene fibers were also subjected to a modification treatment. The specific modification method is as follows:

[0106] The polypropylene fibers were preheated at 62.5 °C for 1 h, the preheated polypropylene fibers were stirred thoroughly in a sufficient amount of sulfuric acid solution, and then washed with water, filtered by suction, and dried;

[0107] The dried polypropylene fibers were ultrasonically modified in a modification solution 4 times the total amount of polypropylene fibers. After the ultrasonic treatment was completed, they were filtered by suction and dried. The modification solution includes the following raw materials in parts by weight: 3.5 parts of a sodium silicate solution with a mass fraction of 5%, 4 parts of a hydrochloric acid dopamine solution with a mass fraction of 2%, 6.5 parts of boron nitride, and 2.5 parts of calcium titanate.

[0108] Optimization Example 2: On the basis of Example 1, the polypropylene fibers were also subjected to a modification treatment. The specific modification method is as follows:

[0109] The polypropylene fibers were preheated at 62.5 °C for 1 h, the preheated polypropylene fibers were stirred thoroughly in a sufficient amount of sulfuric acid solution, and then washed with water, filtered by suction, and dried;

[0110] The dried polypropylene fibers were ultrasonically modified in a modification solution 4 times the total amount of polypropylene fibers. After the ultrasonic treatment was completed, they were filtered by suction and dried. The modification solution includes the following raw materials in parts by weight: 3.5 parts of a sodium silicate solution with a mass fraction of 5% and 4 parts of a hydrochloric acid dopamine solution with a mass fraction of 2%.

[0111]

[0112] It can be seen from Optimization Examples 1-2 that after the polypropylene fibers are subjected to the specific improvement treatment of the present invention, the compressive strength and flexural toughness of the product are further improved. And the change of the modification solution fails to achieve the technical effect of the present invention. The polypropylene fibers modified by the modification solution obtained by the specific method of the present invention have the most significant performance effect.

[0113] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

[0114] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A lightweight and highly ductile concrete, characterized in that, It includes the following raw materials in parts by weight: 43-45 parts of cement, 13-15 parts of fly ash, 11-12 parts of silica fume, 11-13 parts of water, 5-7 parts of shale sand, 7-21 parts of shale ceramsite, 1-1.5 parts of water reducer, 0.05-0.07 parts of defoamer, 4.5-5.5 parts of steel fiber, 0.12-0.16 parts of polypropylene fiber; Polypropylene fiber is also modified. The specific modification method is: Preheat the polypropylene fiber at 60-65℃ for 1 hour, stir the preheated polypropylene fiber in sufficient sulfuric acid solution, then wash with water, filter and dry; Ultrasonic modification treatment is performed on the dried polypropylene fiber in a modification solution that is 3-5 times the total amount of the polypropylene fiber. After the ultrasonic modification is completed, the fiber is filtered and dried. The modified liquid comprises the following raw materials in parts by weight: 2-5 parts by weight of 5% sodium silicate solution, 3-5 parts by weight of 2% dopamine hydrochloride solution, 5-8 parts by weight of boron nitride and 2-3 parts by weight of calcium titanate.

2. The lightweight and high-toughness concrete according to claim 1, characterized in that The cement is 52.5 ordinary Portland cement; The fly ash is first-grade fly ash; The specific surface area of the silica fume ≥ 19000 m 2 / kg, and the SiO2 content ≥ 90%.

3. A lightweight and highly ductile concrete according to claim 1, characterized in that, The shale ceramsite sand is of grade 900, with a bulk density of 900 kg / m 3 ~1400 kg / m 3 , composed of sizes ranging from 0 to 5 mm, where the mass ratios of shale ceramsite sand with sizes of 0-3 mm and 3-5 mm are 80% and 20% respectively, the cylinder compressive strength is greater than 4 MPa, and the chemical components are silicon dioxide, alumina, iron oxide, and calcium oxide; the bulk density of the shale ceramsite is 1000 kg / m 3 ~1400 kg / m 3 , composed of sizes ranging from 5 to 10 mm, with an irregular polyhedron shape, the cylinder compressive strength is greater than 3 MPa, the 24-hour water absorption rate is 9%, and the stacking porosity is greater than 26%.

4. A lightweight and high-toughness concrete according to claim 1, characterized in that, The water reducer is a polycarboxylate water reducer; The main component of the defoamer is modified silicone; The steel fiber is a copper-plated thin straight steel fiber with a length of 12 mm and a diameter of 0.12 mm.

5. A lightweight and highly ductile concrete according to claim 1, wherein, The mass fraction of the sulfuric acid solution is 5-8%.

6. A lightweight and highly ductile concrete according to claim 1, characterized in that, The ultrasonic modification treatment is performed at an ultrasonic power of 450-500W and the ultrasonic treatment is performed for 1 hour.

7. A lightweight and highly ductile concrete according to claim 1, characterized in that, The polypropylene fiber has a length of 12 mm, a diameter of 27 μm, and a tensile strength of 625 MPa.

8. The preparation method of a lightweight and high-toughness concrete according to any one of claims 1-7, characterized in that, The following steps are involved: S1. Pre-wetting the shale ceramsite to obtain pre-wetted shale ceramsite; S2. The cement, fly ash and silica fume were added to a forced mixer and dry stirred for 1 min. The raw materials were thoroughly mixed to obtain a first mixture. S3. The water and the water reducing agent, the defoaming agent were mixed and stirred to obtain a second mixture, and then the second mixture was added to the first mixture and continued to mix to obtain a mortar; Then add shale sand and pre-wetted shale ceramsite to the mortar in S3 and stir for 1-2 minutes so that the shale sand and pre-wetted shale ceramsite can be wrapped by the mortar; S4. Finally, add steel fiber and polypropylene fiber to the mixing equipment and stir thoroughly for 1-2 minutes to form the concrete; S5. The concrete is formed in a mold and then maintained in a moisturizing condition.

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