A porous lightweight metallic ultra-high performance concrete composite material and its preparation method

Abstract

This invention discloses a porous metal lightweight ultra-high performance concrete composite material and its preparation method. The porous metal lightweight ultra-high performance concrete composite material includes porous metal A cut into a predetermined shape as an integral skeleton, granular porous metal B, and lightweight ultra-high performance concrete slurry C. The lightweight ultra-high performance concrete slurry C includes cementitious materials, pre-wetted lightweight aggregate, fiber, water, water-reducing agent, and functional admixtures. The cementitious materials include 40-60% cement, 15-25% silica fume, 10-20% lightweight cenospheres, and 15-30% hollow microspheres by mass percentage, and the sum of the mass percentages of cement, silica fume, lightweight cenospheres, and hollow microspheres is 100%. The composite material composed of lightweight ultra-high performance concrete and porous metal of this invention has a certain degree of improved compressive strength and its ultimate strain is increased by more than 100%, and its energy absorption efficiency is significantly improved when used in anti-collision structures.

Description

Technical Field

[0001] This invention relates to lightweight ultra-high performance concrete, specifically to a porous metallic lightweight ultra-high performance concrete composite material and its preparation method. Background Technology

[0002] Ultra-high performance concrete (UHPC) is designed based on the theory of closest particle packing, possessing ultra-high mechanical properties, toughness, and durability. It is currently widely used in bridges, highways, tunnels, military engineering, thin-walled structures, and highly abrasive and corrosive environments, promoting the development of transportation infrastructure towards high quality, long lifespan, and high durability. However, conventional methods for preparing UHPC utilize large amounts of cement, silica fume, and other binding materials, resulting in high heat of hydration and high viscosity, which are detrimental to on-site construction and early crack control. Furthermore, conventional UHPC materials have a density as high as 2600 kg / m³. 3 The above increases the self-weight load of the structure.

[0003] Currently, there are many solutions that use lightweight aggregates such as ceramsite, shale, and expanded perlite to replace quartz sand, which can reduce the density of UHPC to 2000 kg / m³. 3 However, during construction, the homogeneity of lightweight UHPC inevitably suffers from insufficient material homogeneity due to the floating of lightweight aggregates, limiting its further lightweight development and large-scale engineering applications. Porous metals are a new type of engineering material that integrates function and structure, possessing lightweight properties (generally less than 400 kg / m³). 3 With its characteristics of high porosity (porosity can reach over 90%), high strength (specific strength), and good energy absorption, porous metals are widely used in filtration and purification, battery electrodes, catalyst supports, and damping materials. However, there are few reports on the use of porous metals in the preparation of ultra-high performance concrete.

[0004] Therefore, it is necessary to develop a functional lightweight ultra-high performance concrete composite material containing porous metal and its preparation method, in order to further reduce its self-weight and solve the problem of lightweight raw materials floating in lightweight UHPC, and improve the density and volume stability of the composite material. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a functional lightweight ultra-high performance concrete composite material containing porous metal and its preparation method, which is used to further reduce the self-weight and solve the problem of lightweight raw materials floating in lightweight UHPC, and improve the density and volume stability of the composite material.

[0006] The technical solution of this invention is: a porous metal lightweight ultra-high performance concrete composite material, characterized in that it comprises porous metal A cut into a predetermined shape as an integral skeleton, granular porous metal B, and lightweight ultra-high performance concrete slurry C, wherein the ratio of the absolutely dense volume of porous metal A, the natural volume of porous metal B, and the natural volume of lightweight ultra-high performance concrete slurry C is (0.05-0.1):(0.015-0.03):1.

[0007] The porous metal A is made of one of the following materials: aluminum foam, aluminum foam alloy, stainless steel foam, magnesium foam, or magnesium foam alloy. It has an interconnected open-cell structure and a density range of 300 kg / m³. 3 ~600kg / m 3 Porosity 80%–95%, pore size range 2mm–5mm;

[0008] The porous metal B material is one of the following: aluminum foam, aluminum foam alloy, magnesium foam, magnesium foam alloy, copper foam, copper foam alloy, nickel foam, and nickel foam alloy, with a density range of 800 kg / m³. 3 ~1200kg / m 3 The particle size is 1-3 mm, the porosity is 50%-80%, and the pore size range is 10 μm-100 μm;

[0009] The lightweight ultra-high performance concrete paste C comprises cementitious materials, pre-wetted lightweight aggregate, fiber, water, water-reducing agent, and functional admixture. The cementitious materials comprise, by mass percentage, 40-60% cement, 15-25% silica fume, 10-20% lightweight cenospheres, and 15-30% hollow microspheres. The sum of the mass percentages of the cement, silica fume, lightweight cenospheres, and hollow microspheres is 100%. The mass ratio of the cementitious materials to the pre-wetted lightweight aggregate, fiber, water, water-reducing agent, and functional admixture is 1:(0.2-0.5):(0.01-0.02):(0.16-0.22):(0.02-0.04):(0.01-0.03).

[0010] In the technical solution of this invention, based on the pore structure characteristics of porous metals, porous metals are used as both an overall skeleton structure and a local skeleton structure. Porous metal A, serving as the overall skeleton structure, has a large-diameter open-pore structure, while porous metal B, serving as the local skeleton structure, has a microporous structure with either open or closed pores. Both porous metals A and B exhibit high porosity. Since a large amount of lightweight raw materials are used in the preparation of lightweight ultra-high performance concrete, the density of this composite material can be controlled at a relatively low level. Furthermore, both porous metals A and B in the composite material can absorb energy during stress, dissipating energy during the failure of lightweight ultra-high performance concrete and thus improving the overall failure strength of the material. As the overall skeleton structure of the composite material, porous metal A's pores are filled by porous metal B and the lightweight ultra-high performance concrete slurry. Simultaneously, the network structure of porous metal A prevents the lightweight components in the porous metal B and the lightweight ultra-high performance concrete slurry from floating or stratifying under gravity, thus contributing to improved overall material homogeneity. Porous metal B, as a local skeleton structure, is used to replace steel fibers in conventional ultra-high performance concrete to enhance lightweight ultra-high performance concrete. At the same time, the porous structure of porous metal B is beneficial for absorbing loads during the composite material bearing process, absorbing energy during structural failure, improving the structural strength of the material, and helping to reduce the density of the composite material.

[0011] In the technical solution of this invention, the absolute dense volume V of the porous metal A can be calculated from the porosity P and the natural volume V0. The three components V, P, and V0 have the following relationship:

[0012] P = (V0 - V) / V0 * 100%

[0013] Where P is porosity.

[0014] V0 is the natural volume (the volume of the material in its natural state), in meters (m). 3 ;

[0015] V is the absolutely dense volume, in meters (m). 3 .

[0016] For porous metal B and lightweight ultra-high performance concrete paste C, the quantities can be taken according to their natural volume (volume under natural conditions).

[0017] Preferably, in the cementitious material: the hollow microspheres are hollow glass microspheres or hollow ceramic microspheres, the hollow microspheres have a suspension rate greater than 92% and an apparent density in the range of 300 kg / m³. 3 ~600kg / m 3The particle size distribution ranges from 5μm to 100μm, and the compressive strength is greater than 50MPa. Hollow glass microspheres are lightweight, high-strength, and ultrafine. Using them as a cementitious component in lightweight ultra-high performance concrete not only helps optimize the composition and gradation of the material and achieve close packing, but also enables the lightweighting of the ultra-high performance concrete paste and enhances the material strength.

[0018] Preferably, in the cementitious material:

[0019] The cement is of one of the following strength grades: 52.5, 52.5R, 62.5, or 62.5R.

[0020] Lightweight cenospheres are hollow spheres with a suspension rate greater than 90%, a particle size distribution range of 30μm to 500μm, and an average particle size range of 100μm to 200μm.

[0021] The silica fume has a SiO2 content of not less than 90% and an average particle size range of 0.1μm to 0.5μm.

[0022] The functions of the above raw materials are as follows: In order to ensure that the strength index of lightweight ultra-high performance concrete meets the requirements, silicate cement with a strength grade of not less than 52.5 must be selected; the spherical structure of lightweight cenospheres can improve the fluidity of lightweight ultra-high performance concrete. In addition, its hollow structure helps to achieve the lightweighting of ultra-high performance concrete paste; silica fume can fill the paste interface area to improve the density of the paste and improve the strength and durability of the material.

[0023] Preferably, the pre-wetted lightweight aggregate is obtained by the following treatment: lightweight aggregate and water are weighed at a mass ratio of (10-15):1, and water is added evenly in 3-5 applications and sprayed onto the surface of the lightweight aggregate, and mixed repeatedly until the water is completely absorbed by the lightweight aggregate and there is no visible water on the surface; the lightweight aggregate is one of ceramsite, sintered coal gangue, steam-cured silicate particles, cenospheres, and sintered hollow spheres, with a particle size range of 0.38mm-2.36mm and an apparent density range of 1000kg / m³. 3 ~1800kg / m 3 Pre-wetting lightweight aggregates serves two purposes: firstly, it prevents the aggregates from absorbing free water from the slurry, thus reducing the slurry's fluidity; secondly, the water in the pre-wetted lightweight aggregates provides the necessary moisture for the later hydration of the cementitious materials, improving the material's later strength. Lightweight aggregates, as the aggregates in lightweight ultra-high performance concrete, are essential for achieving the lightweighting of ultra-high performance concrete.

[0024] Preferably, the fiber is one of polypropylene fiber, polyvinyl alcohol fiber, polyethylene fiber, polyphenylene sulfide fiber, or poly(p-phenylenebenzobisoxazole) (PBO) fiber, with a fiber length of 6 mm to 10 mm. The density of organic fibers is only 1% to 2% of that of steel fibers commonly used in UHPC, which can significantly reduce the density of lightweight ultra-high performance concrete slurry. In addition, organic fibers are very soft, and through the overlapping action of the fibers, porous metal B can be cross-linked with the lightweight ultra-high performance concrete slurry, improving the integrity and homogeneity of the composite material.

[0025] Preferably, the water-reducing agent is a polycarboxylate superplasticizer with a water reduction rate of not less than 30%. Since lightweight ultra-high performance concrete paste uses a large amount of ultrafine powder, it is necessary to ensure the workability of the material with a low water content; therefore, the water-reducing agent used must have a high water reduction rate.

[0026] Preferably, the functional admixture is a calcium-based expansive clinker with a 7-day restricted expansion rate of not less than 0.15%. Because lightweight ultra-high performance concrete has a high cement content and large volume shrinkage, commonly used expansive agents are difficult to achieve the effect of volume control; therefore, an expansive clinker with a high expansion rate is selected.

[0027] Preferably, the cementitious material comprises 50-55% cement, 15-20% silica fume, 12-15% lightweight cenospheres, and 15-20% hollow microspheres by mass percentage, wherein the sum of the mass percentages of the cement, silica fume, lightweight cenospheres, and hollow microspheres is 100%.

[0028] The mass ratio of the cementitious material to the pre-wetted lightweight aggregate, fiber, water, water-reducing agent, and functional admixture is 1:(0.3~0.35):(0.012~0.015):(0.18~0.20):(0.021~0.025):(0.01~0.02).

[0029] Preferably, the porous metallic lightweight ultra-high performance concrete composite material has a density of 1400 kg / m³. 3 ~1800kg / m 3 The 28-day compressive strength is greater than 100 MPa. The ultimate strain of the composite material is greater than 7000 με.

[0030] This invention also provides a method for preparing the above-mentioned porous lightweight ultra-high performance concrete composite material, characterized by comprising the following steps:

[0031] 1) Pre-cut porous metal A according to the shape of the concrete mold, and place porous metal A in the concrete mold as the overall skeleton;

[0032] 2) Cement, lightweight cenospheres, silica fume, hollow microspheres, pre-wetted lightweight aggregate, fiber, water, water-reducing agent and functional admixture are mixed to obtain lightweight ultra-high performance concrete paste C;

[0033] 3) Continue mixing the porous metal B with the lightweight ultra-high performance concrete slurry C, and inject the resulting slurry into the concrete mold to fill the pores of the porous metal A, thereby obtaining a functional lightweight ultra-high performance concrete composite material containing porous metal.

[0034] Preferably, the pre-wetted lightweight aggregate is obtained by the following treatment: lightweight aggregate and water are weighed at a mass ratio of (10-15):1, and water is added evenly in 3-5 applications and sprayed onto the surface of the lightweight aggregate, and mixed repeatedly until the water is completely absorbed by the lightweight aggregate and there is no visible water on the surface; the lightweight aggregate is one of ceramsite, sintered coal gangue, steam-cured silicate particles, cenospheres, and sintered hollow spheres, with a particle size range of 0.38mm-2.36mm and an apparent density range of 1000kg / m³. 3 ~1800kg / m 3 .

[0035] The beneficial effects of this invention are as follows:

[0036] 1. Utilizing the high porosity of porous metals, both A and B, are used as the overall and local skeleton structures of lightweight ultra-high performance concrete composites. Both porous metals play a role in absorbing energy during material stress, dissipating energy during the failure of lightweight ultra-high performance concrete and thus improving the overall failure strength of the material. Furthermore, porous metal A, used in the overall skeleton structure, prevents lightweight components in the lightweight ultra-high performance concrete slurry from floating or stratifying under gravity, contributing to improved overall material homogeneity. Porous metal B, as a local skeleton structure, replaces steel fibers in conventional ultra-high performance concrete to strengthen it. Simultaneously, the porous structure of porous metal B is beneficial for absorbing loads during composite material loading, absorbing energy during structural failure, and improving the structural strength of the material.

[0037] 2. The lightweight components in lightweight ultra-high performance concrete paste C achieve the lightweighting of ultra-high performance concrete. The continuous particle size distribution of cement, lightweight cenospheres, silica fume, and hollow microspheres in the cementitious materials ensures the densest packing of lightweight ultra-high performance concrete. The spherical structure of lightweight cenospheres improves the fluidity of lightweight ultra-high performance concrete. Silica fume, with its small particle size, fills the voids in the paste, contributing to improved material density and durability. The lightweight, high-strength, and ultrafine characteristics of hollow microspheres not only help optimize the material composition and gradation, achieving dense packing, but also contribute to the lightweighting of ultra-high performance concrete paste, and further enhance material strength.

[0038] 3. In lightweight ultra-high performance concrete paste C, pre-wetted aggregate can serve as an internal curing material, improving the internal humidity field and continuously providing the water needed for cementitious material hydration, thereby enhancing the material's density and volume stability. Organic fibers can reduce the density of lightweight ultra-high performance concrete paste; furthermore, their flexibility allows for cross-linking between porous metals (acting as a local skeleton structure) and the lightweight ultra-high performance concrete paste through fiber overlap, improving the overall integrity and homogeneity of the composite material. The use of calcium-based expansive clinker solves the problem of controlling the volume stability of ultra-high performance concrete.

[0039] 4. The porous, lightweight, ultra-high-performance metallic concrete composite material prepared by this invention has a density of 1400 kg / m³. 3 ~1800kg / m 3 With a 28-day compressive strength greater than 100 MPa and excellent ultimate strain performance, its energy absorption efficiency is significantly improved when used in anti-collision structures. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Unless otherwise specified, the pharmaceuticals used in the following embodiments are commercially available products, and the methods used are conventional methods in the art.

[0041] The requirements for the materials used in the following embodiments are as follows:

[0042] Porous metal A has a three-dimensional interconnected open-cell structure and is made of one of the following materials: aluminum foam, aluminum foam alloy, stainless steel foam, magnesium foam, or magnesium foam alloy, with a density ranging from 300 kg / m³. 3 ~600kg / m 3 Porosity 80%–95%, pore size range 2mm–5mm;

[0043] Porous metal B is one of the following: aluminum foam, aluminum foam alloy, magnesium foam, magnesium foam alloy, copper foam, copper foam alloy, nickel foam, and nickel foam alloy, with a density range of 800 kg / m³. 3 ~1200kg / m 3 The particle size is 1-3 mm, the porosity is 50%-80%, and the pore size range is 10 μm-100 μm;

[0044] Lightweight ultra-high performance concrete C is the core component of the composite material, with a density only 50% to 60% of that of conventional ultra-high performance concrete, significantly reducing the density of the composite material. The material requirements for lightweight ultra-high performance concrete C are as follows:

[0045] The cement is commercially available silicate cement, and the grade can be selected from one of the following strength grades: 52.5, 52.5R, 62.5, or 62.5R.

[0046] Lightweight cenospheres are hollow spheres with a suspension rate greater than 90%, a particle size distribution range of 30μm to 500μm, and an average particle size range of 100μm to 200μm.

[0047] The silica fume has a SiO2 content of not less than 90 wt% and an average particle size range of 0.1 μm to 0.5 μm.

[0048] Hollow microspheres are one of hollow glass microspheres or hollow ceramic microspheres. They are hollow spheres with a suspension rate greater than 92% and an apparent density ranging from 300 kg / m³. 3 ~600kg / m 3 The particle size distribution ranges from 5μm to 100μm, and the compressive strength is greater than 50MPa.

[0049] The pre-wetted lightweight aggregate treatment method is as follows: Weigh the lightweight aggregate and water at a mass ratio of (10-15):1, then add the water evenly in 3-5 applications, spraying it onto the aggregate surface, mixing repeatedly until the water is completely absorbed by the lightweight aggregate and there is no visible water on the surface. The lightweight aggregate is one of the following: ceramsite, sintered coal gangue, autoclaved silicate granules, cenospheres, or sintered hollow spheres, with a particle size range of 0.38mm-2.36mm and an apparent density range of 1000kg / m³. 3 ~1800kg / m 3 .

[0050] The fiber is one of polypropylene (PP) fiber, polyvinyl alcohol (PVA) fiber, polyethylene (PE) fiber, polyphenylene sulfide (PPS) fiber, or poly(p-phenylene benzobisoxazole) (PBO) fiber, with a fiber length of 6 mm to 10 mm.

[0051] The water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate of not less than 30%.

[0052] The functional admixture is a calcium-based expanding agent for clinker, with a 7-day restricted expansion rate of not less than 0.15%.

[0053] Example 1

[0054] This embodiment provides a functional lightweight ultra-high performance concrete composite material containing porous metal, as shown in Table 1, containing the following raw materials:

[0055] Porous metal A is made of aluminum foam with a density of 450 kg / m³. 3 The porosity is 85%, and the pore size ranges from 3 to 5 mm;

[0056] Porous metal B is made of foamed magnesium alloy with a specific density of 850 kg / m³. 3The particle size range is 1–1.5 mm, the porosity is 52%, and the pore size range is 15–45 μm;

[0057] Lightweight ultra-high performance concrete C comprises the following components by weight: 100 parts cementitious materials, 30 parts pre-wetted lightweight aggregate (pre-wetted steam-cured silicate particles), 1.2 parts polyvinyl alcohol (PVA) fiber, 18 parts water, 2.5 parts water-reducing agent, and 1.8 parts functional admixtures.

[0058] 100 parts of cementitious material contain: 50 parts cement (strength grade 52.5), 12 parts lightweight cenospheres, 18 parts silica fume, and 20 parts hollow glass microspheres.

[0059] As shown in Table 2, the ratio of the absolute dense volume of porous metal A, the natural volume of porous metal B, and the natural volume of lightweight ultra-high performance concrete C is 0.06:0.018:1.

[0060] The preparation method of the functional lightweight ultra-high performance concrete composite material containing porous metal in this embodiment includes the following steps:

[0061] 1) Pre-cut porous metal A according to the shape of the concrete mold (usually a block shape), and place porous metal A in the concrete mold as the overall skeleton;

[0062] 2) Cement, lightweight cenospheres, silica fume, hollow microspheres, pre-wetted lightweight aggregate, fiber, water, water-reducing agent and functional admixture are mixed to obtain lightweight ultra-high performance concrete paste C;

[0063] 3) Continue mixing the porous metal B with the lightweight ultra-high performance concrete slurry C, and inject the resulting slurry into the concrete mold to fill the pores of the porous metal A, thereby obtaining a functional lightweight ultra-high performance concrete composite material containing porous metal.

[0064] Example 2

[0065] This embodiment provides a functional lightweight ultra-high performance concrete composite material containing porous metal, as shown in Table 1, containing the following raw materials:

[0066] Porous metal A is made of aluminum foam with a density of 450 kg / m³. 3 The porosity is 85%, and the pore size ranges from 3 to 5 mm;

[0067] Porous metal B is made of foamed magnesium alloy with a specific density of 800 kg / m³. 3 The particle size range is 1–1.5 mm, the porosity is 56%, and the pore size range is 15–30 μm;

[0068] Lightweight ultra-high performance concrete C comprises the following components by weight: 100 parts cementitious materials, 35 parts pre-wetted lightweight aggregate (pre-wetted steam-cured silicate particles), 1.2 parts polyvinyl alcohol (PVA) fiber, 20 parts water, 2.1 parts water-reducing agent, and 1.8 parts functional admixtures.

[0069] 100 parts of cementitious material contain: 55 parts cement (strength grade 52.5), 15 parts lightweight cenospheres, 15 parts silica fume, and 15 parts hollow ceramic microspheres.

[0070] As shown in Table 2, the ratio of the absolute dense volume of porous metal A, the natural volume of porous metal B, and the natural volume of lightweight ultra-high performance concrete C is 0.06:0.02:1.

[0071] The preparation method of the functional lightweight ultra-high performance concrete composite material containing porous metal in this embodiment includes the following steps:

[0072] 1) Pre-cut porous metal A according to the shape of the concrete mold (usually a block shape), and place porous metal A in the concrete mold as the overall skeleton;

[0073] 2) Mix cement, lightweight cenospheres, silica fume, hollow microspheres, pre-wetted lightweight aggregate, organic fiber, water, water-reducing agent and functional admixture to obtain lightweight ultra-high performance concrete paste C;

[0074] 3) Continue mixing the porous metal B with the lightweight ultra-high performance concrete slurry C, and inject the resulting slurry into the concrete mold to fill the pores of the porous metal A, thereby obtaining a functional lightweight ultra-high performance concrete composite material containing porous metal.

[0075] Example 3

[0076] This embodiment provides a functional lightweight ultra-high performance concrete composite material containing porous metal, as shown in Table 1, containing the following raw materials:

[0077] Porous metal A is made of aluminum foam with a density of 450 kg / m³. 3 The porosity is 85%, and the pore size ranges from 3 to 5 mm;

[0078] Porous metal B, made of foamed magnesium alloy, with a specific density of 900 kg / m³. 3 The particle size range is 1–3 mm, the porosity is 50%, and the pore size range is 20–50 μm;

[0079] Lightweight ultra-high performance concrete C comprises the following components by weight: 100 parts cementitious materials, 35 parts pre-wetted lightweight aggregate (pre-wetted perlite particles), 1.2 parts polyvinyl alcohol (PVA) fiber, 18 parts water, 2.5 parts water-reducing agent, and 1.8 parts functional admixtures.

[0080] 100 parts of cementitious material contain: 50 parts cement (strength grade 52.5), 15 parts lightweight cenospheres, 15 parts silica fume, and 20 parts hollow glass microspheres.

[0081] As shown in Table 2, the ratio of the absolute dense volume of porous metal A, the natural volume of porous metal B, and the natural volume of lightweight ultra-high performance concrete C is 0.08:0.016:1.

[0082] The preparation method of the functional lightweight ultra-high performance concrete composite material containing porous metal in this embodiment includes the following steps:

[0083] 1) Pre-cut porous metal A according to the shape of the concrete mold (usually a block shape), and place porous metal A in the concrete mold as the overall skeleton;

[0084] 2) Mix cement, lightweight cenospheres, silica fume, hollow microspheres, pre-wetted lightweight aggregate, organic fiber, water, water-reducing agent and functional admixture to obtain lightweight ultra-high performance concrete paste C;

[0085] 3) Continue mixing the porous metal B with the lightweight ultra-high performance concrete slurry C, and inject the resulting slurry into the concrete mold to fill the pores of the porous metal A, thereby obtaining a functional lightweight ultra-high performance concrete composite material containing porous metal.

[0086] Table 1. Mix proportions of lightweight ultra-high performance concrete (total cementitious materials: 100 parts)

[0087]

[0088] Table 2. Mix Proportion of Porous Metal Lightweight Ultra-High Performance Concrete Composite Material

[0089]

[0090] Performance testing

[0091] The lightweight ultra-high performance concrete C from Example 1 was used as a comparative example. The porous metallic lightweight ultra-high performance concrete composites prepared in Examples 1-3 and the products prepared in the comparative example were subjected to performance tests, and the results are shown in Table 3 below.

[0092] Table 3 Performance data of the examples and comparative examples

[0093]

[0094] Table 3 shows that by replacing conventional raw materials with lightweight cenospheres, hollow microspheres, pre-wetted lightweight aggregates, and organic fibers, the density of ultra-high performance concrete (typically 2600 kg / m³) is significantly reduced. 3The compressive strength of the composite material composed of lightweight ultra-high performance concrete and porous metal is reduced by more than 40%, and its ultimate strain is increased by more than 100 MPa. When used in anti-collision structures, its energy absorption efficiency is significantly improved.

Claims

1. A porous, lightweight, ultra-high-performance metallic concrete composite material, characterized in that, The system comprises porous metal A cut into a predetermined shape to form an overall framework, granular porous metal B, and lightweight ultra-high performance concrete slurry C. The ratio of the absolute dense volume of porous metal A, the natural volume of porous metal B, and the natural volume of lightweight ultra-high performance concrete slurry C is (0.05-0.1):(0.015-0.03):

1. The porous metal A is made of one of the following materials: aluminum foam, aluminum foam alloy, stainless steel foam, magnesium foam, or magnesium foam alloy. It has an interconnected open-cell structure and a density range of 300 kg / m³. 3 ~600kg / m 3 Porosity 80%~95%, pore size range 2mm~5mm; The porous metal B material is one of the following: aluminum foam, aluminum foam alloy, magnesium foam, magnesium foam alloy, copper foam, copper foam alloy, nickel foam, and nickel foam alloy, with a density range of 800 kg / m³. 3 ~1200kg / m 3 The particle size is 1~3mm, the porosity is 50%~80%, and the pore size range is 10μm~100μm; The lightweight ultra-high performance concrete paste C comprises cementitious materials, pre-wetted lightweight aggregate, fiber, water, water-reducing agent, and functional admixture. The cementitious materials comprise, by mass percentage, 40-60% cement, 15-25% silica fume, 10-20% lightweight cenospheres, and 15-30% hollow microspheres, with the sum of the mass percentages of cement, silica fume, lightweight cenospheres, and hollow microspheres being 100%. The mass ratio of the cementitious materials to the pre-wetted lightweight aggregate, fiber, water, water-reducing agent, and functional admixture is 1:(0.2-0.5):(0.01-0.02):(0.16-0.22):(0.02-0.04):(0.01-0.03). The hollow microspheres are hollow glass microspheres or hollow ceramic microspheres, and the fibers are organic fibers.

2. The porous metallic lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, The hollow microspheres have a suspension rate greater than 92% and an apparent density in the range of 300 kg / m³. 3 ~ 600kg / m 3 The particle size distribution ranges from 5μm to 100μm, and the compressive strength is greater than 50MPa.

3. The porous metallic lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, In the cementitious material: The cement is of one of the following strength grades: 52.5, 52.5R, 62.5, or 62.5R. Lightweight cenospheres are hollow spheres with a suspension rate greater than 90%, a particle size distribution range of 30μm to 500μm, and an average particle size range of 100μm to 200μm. The silica fume has a SiO2 content of not less than 90% and an average particle size range of 0.1μm to 0.5μm.

4. The porous metallic lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, The pre-wetted lightweight aggregate is obtained by the following treatment: Lightweight aggregate and water are weighed at a mass ratio of (10~15):

1. Water is then added evenly in 3~5 applications and sprayed onto the surface of the lightweight aggregate, mixing repeatedly until the water is completely absorbed and there is no visible water on the surface. The lightweight aggregate is one of sintered coal gangue, steam-cured silicate particles, cenosphere particles, or sintered hollow spheres, with a particle size range of 0.38mm~2.36mm and an apparent density range of 1000kg / m³. 3 ~1800kg / m 3 .

5. The porous metallic lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, The fiber is one of polypropylene fiber, polyvinyl alcohol fiber, polyethylene fiber, polyphenylene sulfide fiber, or poly(p-phenylenebenzobisoxazole) PBO fiber, and the fiber length is 6mm to 10mm.

6. The porous metallic lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, The water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate of not less than 30%.

7. The porous metallic lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, The functional additive is a calcium-based expansion agent for clinker, with a 7-day restricted expansion rate of not less than 0.15%.

8. The porous metallic lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, The cementitious material comprises, by mass percentage, 50-55% cement, 15-20% silica fume, 12-15% lightweight cenospheres, and 15-20% hollow microspheres, wherein the sum of the mass percentages of the cement, silica fume, lightweight cenospheres, and hollow microspheres is 100%. The mass ratio of the cementitious material to the pre-wetted lightweight aggregate, fiber, water, water-reducing agent, and functional admixture is 1:(0.3~0.35):(0.012~0.015):(0.18~0.20):(0.021~0.025):(0.01~0.02).

9. The porous metallic lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, The porous lightweight ultra-high performance concrete composite material has a density of 1400 kg / m³. 3 ~1800kg / m 3 The 28-day compressive strength is greater than 100 MPa.

10. A method for preparing the porous lightweight ultra-high performance concrete composite material as described in claim 1, characterized in that, Includes the following steps: 1) Pre-cut porous metal A according to the shape of the concrete mold, and place porous metal A in the concrete mold as the overall skeleton; 2) Cement, lightweight cenospheres, silica fume, hollow microspheres, pre-wetted lightweight aggregate, fiber, water, water-reducing agent and functional admixture are mixed to obtain lightweight ultra-high performance concrete paste C; 3) Continue mixing the porous metal B with the lightweight ultra-high performance concrete slurry C, and inject the resulting slurry into the concrete mold to fill the pores of the porous metal A, thereby obtaining a functional lightweight ultra-high performance concrete composite material containing porous metal.

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