Heavy load durable field concrete pavement RPC and preparation method thereof

Abstract

This invention discloses a heavy-duty durable airport pavement RPC and its preparation method, comprising the following components in parts by weight: 15-30 parts silica fume, 20-50 parts mineral powder, 0-25 parts fly ash, 0-25 parts microspheres, 8-15 parts graphene, 1.5-8 parts composite microsurfactant, 8-25 parts aerosol powder, and 10-15 parts retarding high-efficiency water-reducing agent. The composite microsurfactant includes 1-3 parts sodium glutamate and 0.5-5 parts sodium carboxymethyl cellulose. The heavy-duty durable airport pavement RPC provided by this invention, with solid waste materials as the main body, combined with composite microsurfactants and retarding high-efficiency water-reducing agents, can significantly improve the flexural strength and freeze-thaw resistance of airport pavement concrete when used in concrete, improve the performance of airport pavement concrete, ensure the service life of airport pavement, reduce the amount of maintenance work, and lower construction and maintenance costs.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to heavy-duty durable concrete pavement RPC and its preparation method. Background Technology

[0002] Airport pavements, as the core load-bearing structure for aircraft takeoff, landing, taxiing, and parking, operate in extremely harsh and complex environments for extended periods. This environment places far more stringent performance requirements on concrete materials than on ordinary road surfaces: First, the pavement must withstand the immense impact, compaction, and fatigue stress from aircraft loads, demanding extremely high flexural strength, toughness, and abrasion resistance from the concrete. It is particularly noteworthy that with the significant increase in airport usage frequency in recent years, the current design standard of 5 MPa flexural strength is insufficient to meet practical needs under frequent heavy loads. Effectively improving flexural strength has become a core technical challenge for airport pavement concrete. Furthermore, airport pavements suffer from concrete strength stratification, with the upper layer often exhibiting a strength 30% lower than the lower layer. This significant strength gradient severely weakens the overall load-bearing capacity and service life of the pavement structure. Second, the pavement is extensively exposed to the natural environment, directly subjected to sunlight, rain, freeze-thaw cycles, and chemical erosion from de-icing salts in northern regions. This necessitates that the concrete possess excellent freeze-thaw resistance, low permeability, and chemical corrosion resistance. Furthermore, to ensure construction quality and operational safety, concrete must also possess good workability, volume stability, and low shrinkage to prevent cracking and warping during large-scale construction. Therefore, improving the flexural strength and durability of airport pavement concrete and extending its overhaul cycle is of great economic and social significance for ensuring flight safety and reducing operation and maintenance costs.

[0003] Traditionally, improving concrete performance has primarily relied on increasing cement content or strength grade. However, this not only significantly increases costs and carbon emissions but can also lead to temperature cracks due to excessive heat of hydration, ultimately compromising long-term durability. Adding admixtures to concrete has become a key technological approach to improve concrete microstructure and enhance durability. However, in the specific application scenario of airport pavement, existing admixtures often struggle to achieve a comprehensive balance across multiple key performance indicators, such as high workability, high durability, and low shrinkage.

[0004] On the other hand, against the backdrop of the global advocacy for "low-carbon, environmentally friendly, and green development," the transformation of the building materials industry towards resource conservation and environmental friendliness is an inevitable trend. my country generates a massive amount of industrial solid waste annually, such as fly ash, metallurgical slag, and tailings. Their storage not only occupies land but also poses environmental risks. Utilizing these solid wastes in a resource-efficient and high-value manner to produce high-performance concrete admixtures fully aligns with the national green, circular, and low-carbon development strategy, yielding significant environmental and economic benefits.

[0005] Therefore, in order to overcome the performance shortcomings of existing admixtures and deeply integrate the green concept of solid waste resource utilization, this invention develops a heavy-load durable airport pavement concrete RPC (RPC is an international term for admixtures or active powders) that uses solid waste raw materials and is specifically suitable for airport pavement concrete. By optimizing the particle size distribution and introducing active micro powders, the density of the pavement concrete can be significantly increased, thereby effectively reducing or even eliminating the strength difference between the upper and lower layers of the pavement concrete, while also meeting the service requirements of airport pavement concrete under high-frequency and heavy-load conditions. Summary of the Invention

[0006] Based on the shortcomings of the existing technology, this invention prepares a heavy-duty durable airport pavement RPC, which uses solid waste materials as the main body and combines it with composite micro surfactants and retarding high-efficiency water-reducing agents. When used in concrete, it can significantly improve the flexural strength and freeze-thaw resistance of airport pavement concrete, improve the performance of airport pavement concrete, ensure the service life of airport pavement, reduce the amount of maintenance work on airport pavement, and reduce construction and maintenance costs.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problem is as follows:

[0008] The heavy-duty durable pavement concrete RPC of the present invention comprises the following components in the following proportions: 15-30 parts silica fume, 20-50 parts mineral powder, 0-25 parts fly ash, 0-25 parts microspheres, 8-15 parts graphene, 1.5-8 parts composite microsurfactant, 8-25 parts aerosol powder, and 10-15 parts retarding high-efficiency water-reducing agent. The composite microsurfactant includes 1-3 parts sodium glutamate and 0.5-5 parts sodium carboxymethyl cellulose.

[0009] Preferably, the microspheres have a particle size of 2-10 μm and an apparent density of 500-700 kg / m³.

[0010] Preferably, the graphene has a specific surface area of ​​2630 m² / g and a particle size of 30-60 μm.

[0011] Preferably, the retarding high-efficiency water-reducing agent is a powder with a water reduction rate of 16-20%.

[0012] Preferably, the aerosol powder is waste solid particulate matter from metal smelting, with a particle size range of 0.5-5μm.

[0013] Preferably, the aerosol powder is a single metal particle, a mixture of multiple metal particles, or an alloy particle.

[0014] Preferably, the aerosol powder originates from a metal smelting plant or from the recycling of waste metal.

[0015] Preferably, the preparation process of the aerosol powder includes the following steps:

[0016] (1) Raw material preparation: collect waste solid particles generated from metal smelting;

[0017] (2) Smelting: The waste solid particles are placed into the smelting equipment, the inside of the equipment is evacuated to remove air and moisture, then inert gas is introduced, and the temperature is raised to melt the waste solid particles to obtain alloy liquid;

[0018] (3) Atomization: The alloy liquid is introduced into the guide pipe at the bottom of the melting equipment. A ring or slit nozzle is provided below the guide pipe. The nozzle sprays high-pressure inert gas. The alloy liquid encounters the high-pressure inert gas flow during the falling process and is atomized into fine droplets. The fine droplets are rapidly solidified in the atomization tower to form alloy powder.

[0019] (4) Post-processing: The solidified alloy powder particles are settled in the collection tank at the bottom of the atomizing tower, and then annealed and dried to obtain aerosol powder.

[0020] Preferably, the pressure of the high-pressure inert gas in step (3) is 6-12 MPa.

[0021] Another technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned heavy-load durable pavement RPC, comprising the following steps:

[0022] S1. Mixing: Add silica fume, mineral powder, fly ash, microspheres, graphene, composite micro surfactant and retarding high-efficiency water-reducing agent into a mixer in proportion and mix evenly to obtain mixed powder A;

[0023] S2. Airflow crushing: Mixed powder A is crushed by an airflow crusher and then sieved to obtain mixed powder B;

[0024] S3. Mixing: Add the mixed powder B and the aerosol powder to the mixer in proportion and mix thoroughly to obtain powdered RPC.

[0025] The beneficial effects of this invention are mainly reflected in the following aspects:

[0026] 1. This invention uses solid waste raw materials to prepare special RPC. Adding RPC to concrete reduces the heat of hydration of concrete and reduces cracking without damaging the concrete mechanism.

[0027] 2. When the RPC of this invention is applied to airport pavement concrete, it can improve the quality of concrete by more than 50%. When used in ultra-high performance concrete, it can reduce the amount of non-renewable energy by 50%, increase the flexural and tensile strength of concrete by more than 50%, extend the service life of airport pavement cement concrete, effectively reduce maintenance costs during the service life, and thus reduce resource waste and energy consumption. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The heavy-duty durable pavement concrete RPC of the present invention comprises the following components in the specified proportions: 15-30 parts silica fume, 20-50 parts mineral powder, 0-25 parts fly ash, 0-25 parts microspheres, 8-15 parts graphene, 1.5-8 parts composite microsurfactant, 8-25 parts aerosol powder, and 10-15 parts retarding high-efficiency water-reducing agent. The composite microsurfactant comprises 1-3 parts sodium glutamate and 0.5-5 parts sodium carboxymethyl cellulose. Wherein:

[0030] Using solid waste materials such as silica fume, mineral powder, fly ash, microspheres, graphene, and aerosol powder in concrete can improve its strength, but it can also increase its viscosity, making construction difficult. However, combining composite microsurfactants and retarding high-efficiency water-reducing agents with these solid waste materials and adding them to concrete can reduce friction between cement particles and aggregates, enhancing the fluidity of the mixture and providing lubrication, viscosity reduction, retarding, and water reduction. Applying the RPC of this invention to concrete can reduce the capillary channels within the concrete, decrease the size of air bubbles and the spacing between them, thereby improving the flexural strength and stability of the concrete.

[0031] Aerosol powder is composed of single-element metal particles, mixed particles of multiple metals, or alloy particles, originating from metal smelters or from the recycling of waste metals. The preparation method of aerosol powder includes the following steps:

[0032] (1) Raw material preparation: collect waste solid particles generated from metal smelting;

[0033] (2) Smelting: The waste solid particles are placed into the smelting equipment, the inside of the equipment is evacuated to remove air and moisture, then inert gas is introduced, and the temperature is raised to melt the waste solid particles to obtain alloy liquid;

[0034] (3) Atomization: The alloy liquid is introduced into the guide pipe at the bottom of the melting equipment. A ring or slit nozzle is provided below the guide pipe. The nozzle sprays high-pressure inert gas. During the falling process, the alloy liquid encounters the high-pressure (6-12MPa) inert gas flow and is atomized into fine droplets. The fine droplets are rapidly solidified in the atomization tower to form alloy powder.

[0035] (4) Post-processing: The solidified alloy powder particles are settled in the collection tank at the bottom of the atomizing tower, and then annealed and dried to obtain aerosol powder.

[0036] The preparation method of heavy-load durable concrete pavement RPC includes the following steps:

[0037] S1. Mixing: Add silica fume, mineral powder, fly ash, microspheres, graphene, composite micro surfactant and retarding high-efficiency water-reducing agent into a mixer in proportion and mix evenly to obtain mixed powder A;

[0038] S2. Airflow crushing: Mixed powder A is crushed by an airflow crusher and then sieved to obtain mixed powder B;

[0039] S3. Mixing: Add the mixed powder B and the aerosol powder to the mixer in proportion and mix thoroughly to obtain powdered RPC.

[0040] Silica fume has a particle size smaller than microspheres, which can fill the gaps between microspheres and mineral powder, achieving multi-level particle packing; mineral powder mainly serves as a cementing component, providing later-stage strength, and its particle size is similar to that of graphene, which is beneficial for uniform mixing; fly ash can fill and improve the workability of concrete; the particle size of microspheres is between that of silica fume and mineral powder, which can optimize particle packing density, reduce self-weight, and improve concrete fluidity; aerosol powder is obtained from industrial waste and optimizes particle packing density through inert filling; this invention forms a continuous particle size distribution through silica fume → aerosol powder → microspheres → mineral powder / fly ash → graphene, thereby improving the bulk density of concrete.

[0041] The silica fume is sourced from Sichuan Tiangong New Materials, with an SiO2 content of no less than 92%; S95 mineral powder is selected; Class II fly ash is used; the microspheres have a particle size of 2-10 μm and an apparent density of 500-700 kg / m³, and are ultrafine microspheres from Shandong Hengyuan; the graphene has a specific surface area of ​​2630 m² / g and a particle size of 30-60 μm, and is few-layer graphene, which is an aggregate of graphene nanosheets or micron-sized sheet aggregates; the retarding high-efficiency water-reducing agent is a polycarboxylic acid-based or naphthalene-based agent with a water reduction rate of 16-20%, and is a retarding high-efficiency water-reducing agent (powder) produced by Beijing Keningfeng Admixture Co., Ltd.; the aerosol powder has a particle size range of 0.5-5 μm and is a waste product recovered from metal smelting plants, including steel slag aerosol powder, ore slag aerosol powder, nickel-iron slag aerosol powder, etc., and is steel slag aerosol powder produced by Baowu Group, whose main component is Fe2O3. 40-60%, SiO2 15-25%, CaO 10-20%; the composite microsurfactant is a self-prepared material.

[0042] The RPC of the present invention is made from the above-mentioned materials, including Examples 1-6, and the composition and proportions are shown in Table 1.

[0043] Table 1. Components and proportions of RPC

[0044]

[0045] Technical indicators were tested for Examples 1-6 in Table 1, and the test results are shown in Table 2.

[0046] Table 2 Test results of technical indicators for Examples 1-6

[0047]

[0048] As shown in Table 2, the fineness, water requirement ratio and water content of Examples 1-6 all meet the technical specifications of composite mineral admixtures.

[0049] The aforementioned RPC was used in concrete. The cement used was P.042.5R low-alkali cement, with a 28-day flexural strength of 8.8 MPa and a compressive strength of 48.8 MPa. The fine aggregate was river sand of Zone II grade, with a particle size of 0-4.75 mm, a fineness modulus of 2.73, a density of 2.63 g / cm³, and a bulk density of 1500 kg / m³. 3 The mud content is 1.0%; the coarse aggregate is limestone crushed stone, with a two-stage particle size distribution of 5-20mm and 20-40mm, a density of 2.70g / cm³, and a bulk density of 1620 kg / m³. 3 It contains 0.2% mud, 3.4% needle-like and flaky particles, and RPC is in powder form.

[0050] Based on the requirements of MH5006-2002 "Technical Specification for Construction of Cement Concrete Pavement Surface Layer in Civil Airport Flight Area" and referring to the pavement concrete mix design method in GJB 1112A--2004 "Specification for Construction and Acceptance of Military Airport Runway Engineering", the concrete mix proportion was determined by optimizing the sand ratio, water-cement ratio and the optimal aggregate gradation. Example 1 was selected and added to the concrete.

[0051] Table 3 lists the mix proportions of airport pavement concrete in Example 1 and Comparative Example 1 with different amounts of RPC.

[0052] Table 3. Mix proportions of airport pavement concrete with different amounts of RPC

[0053]

[0054] As shown in Table 3, under the same materials and mix proportions, comparative experiments were conducted on concrete with different RPC admixtures, and the test results are shown in Table 4 below.

[0055] Table 4. Comparison Test Results of Pavement Concrete Mix Proportions in Example 1 and Comparative Example 1

[0056]

[0057] As shown in Table 4, Example 1, with the addition of RPC, exhibits significantly improved density and strength compared to Comparative Example 1 without RPC. Furthermore, with increasing RPC dosage, the concrete density increases, as do the 7-day and 28-day flexural and compressive strengths. The average 28-day flexural strength of the concrete exceeds 8.0 MPa, far exceeding the design requirement of 5.0 MPa for airport pavement concrete. The required frost resistance grade for pavement concrete is F300. The RPC of this invention, when used in concrete, enables the concrete test blocks to achieve a frost resistance grade of F500, greatly improving the service life of pavement concrete in frigid regions. Simultaneously, the increased flexural strength of the concrete conserves non-renewable resources and reduces the thickness of the pavement concrete. For items such as surface smoothness, roughness, and adjacent slab differences, the inspection pass rate reaches 100%, fully meeting the requirements for airport pavement use, ensuring the pavement's design functionality, and effectively extending its service life.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heavy-duty durability concrete pavement RPC, characterized in that, The product comprises the following components in parts by weight: 15-30 parts silica fume, 20-50 parts mineral powder, 0-25 parts fly ash, 0-25 parts microspheres, 8-15 parts graphene, 1.5-8 parts composite microsurfactant, 8-25 parts aerosol powder, and 10-15 parts retarding high-efficiency water-reducing agent. The composite microsurfactant comprises 1-3 parts sodium glutamate and 0.5-5 parts sodium carboxymethyl cellulose.

2. The heavy-duty durability pavement RPC for track concrete pavement according to claim 1, characterized in that: The microspheres are one of expanded vitrified microspheres, hollow microspheres, or vitrified microspheres, with a particle size of 2-10 μm and an apparent density of 500-700 kg / m³.

3. The heavy-duty durability pavement RPC for track concrete pavement according to claim 1, characterized in that: The graphene has a specific surface area of ​​2630 m² / g and a particle size of 30-60 μm.

4. The heavy-duty durability pavement RPC for track concrete pavement according to claim 1, characterized in that: The retarding high-efficiency water-reducing agent is a powder with a water reduction rate of 16-20%.

5. The heavy-duty durability pavement RPC for track concrete pavement according to claim 1, characterized in that: The aerosol powder is waste solid particulate matter from metal smelting, with a particle size range of 0.5-5μm.

6. The heavy-duty durability pavement RPC for track concrete pavement according to claim 1, characterized in that: The aerosol powder is a single metal particle, a mixture of multiple metal particles, or an alloy particle.

7. The heavy-duty durability pavement RPC for track concrete pavement according to claim 1, characterized in that: The aerosol powder comes from metal smelting plants or from the recycling of waste metals.

8. The heavy-duty durability pavement RPC for track concrete pavement according to claim 1, characterized in that: The method for collecting and processing the aerosol powder includes the following steps: (1) Raw material preparation: collect waste solid particles generated from metal smelting; (2) Smelting: The waste solid particles are placed into the smelting equipment, the inside of the equipment is evacuated to remove air and moisture, then inert gas is introduced, and the temperature is raised to melt the waste solid particles to obtain alloy liquid; (3) Atomization: The alloy liquid is introduced into the guide pipe at the bottom of the melting equipment. A ring or slit nozzle is provided below the guide pipe. The nozzle sprays high-pressure inert gas. The alloy liquid encounters the high-pressure inert gas flow during the falling process and is atomized into fine droplets. The fine droplets are rapidly solidified in the atomization tower to form alloy powder. (4) Post-processing: The solidified alloy powder particles are settled in the collection tank at the bottom of the atomizing tower, and then annealed and dried to obtain aerosol powder.

9. The heavy-duty durability pavement RPC for track concrete pavement according to claim 8, characterized in that: The pressure of the high-pressure inert gas in step (3) is 6-12 MPa.

10. The method for preparing heavy-duty durable pavement RPC according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Mixing: Add silica fume, mineral powder, fly ash, microspheres, graphene and composite micro surfactants into a mixer in a certain proportion and mix evenly to obtain mixed powder A; S2. Airflow crushing: Mixed powder A is crushed by an airflow crusher and then sieved to obtain mixed powder B; S3. Mixing: Add the mixed powder B and the aerosol powder to the mixer in proportion and mix thoroughly to obtain powdered RPC.

Images