Special road surface concrete and its preparation method

Abstract

The application relates to the field of pavement materials, and particularly discloses a surface layer concrete for special pavement and a preparation method thereof. The surface layer concrete for special pavement comprises the following raw materials in parts by weight: 380-420 parts of Portland cement, 80-120 parts of slag powder, 30-50 parts of lithium residue powder, 650-720 parts of steel slag sand, 980-1050 parts of basalt crushed stone, 220-260 parts of machine-made sand, 8.5-10.5 parts of polycarboxylic acid high-performance water reducing agent, 6-9 parts of silicon dioxide sol and 100-140 parts of water. The pavement concrete can be used for special pavement of high-grade highways and the like under the conditions of large temperature difference and saline soil, has the advantages of high compressive strength, anti-skid, good wear resistance, anti-freezing and thawing, and anti-sulfate erosion, and prolongs the service life of the road.

Description

Technical Field

[0001] This application relates to the field of road surface materials technology, and more specifically, it relates to a special type of road surface concrete and its preparation method. Background Technology

[0002] Currently, the surface concrete of special-material pavements such as high-grade highways mainly uses ordinary Portland cement-based C40-C50 concrete, with basalt crushed stone as coarse aggregate and natural river sand as fine aggregate, supplemented with conventional water-reducing agents. Mix design and construction are carried out according to JTG / TF30-2014 "Technical Specifications for Construction of Cement Concrete Pavement of Highways" and GB50010-2010 "Code for Design of Concrete Structures". In recent years, in order to improve the level of resource utilization, some projects have tried to incorporate steel slag, recycled aggregates, or a small amount of mineral admixtures (such as fly ash and slag powder). However, the resulting concrete surface layer skid-resistant texture depth is generally less than 0.8mm, the 28-day abrasion loss measured according to GB / T12988-2009 is often higher than 2.5kg / m², and the mass loss rate after 100 freeze-thaw cycles often exceeds 1.2%, making it difficult to meet the service life requirements under the combined effects of high-grade traffic loads and harsh environments.

[0003] Ordinary concrete surface courses suffer from several core defects, including rapid early skid resistance degradation, insufficient long-term wear resistance, weak bonding in the aggregate-paste interface transition zone (ITZ) leading to surface spalling, and poor synergistic performance in freeze-thaw resistance and salt corrosion resistance. Especially on heavy-load highways, the high-frequency shearing action of tires and the de-icing salt erosion work together to cause the actual service life of such concrete surface courses to often be less than 60% of the design life.

[0004] To address the aforementioned issues, existing technologies have proposed various improvement measures. For example, improving initial skid resistance through grooving, roughening, or applying corundum can enhance the surface's macroscopic structure, but this is easily worn down by repeated tire shearing, resulting in poor texture retention. Another approach is to use high-strength cement or incorporate nano-SiO2 for modification, which can increase matrix strength but increases costs by over 30% and significantly reduces the workability of fresh concrete, hindering construction. Chinese patent application CN202410305956.6 discloses a concrete incorporating polypropylene fibers, which improves crack resistance to some extent; however, its improvement in wear resistance is limited, and it fails to address the increased permeability caused by insufficient density in the aggregate-slurry interface transition zone (ITZ), allowing external water and corrosive media to easily penetrate, resulting in an unsatisfactory synergistic improvement in durability.

[0005] Regarding the aforementioned technologies, the inventors believe that existing solutions are insufficient to meet the requirements of special ground material pavements for high skid resistance, high wear resistance, high durability, and long service life under heavy traffic and harsh environmental conditions. Therefore, there is an urgent need to develop a new type of surface concrete that can synergistically improve interface density, surface texture durability, and freeze-thaw and salt corrosion resistance. Summary of the Invention

[0006] In order to improve the skid resistance, wear resistance and durability of special ground material pavements, this application provides a surface concrete for special ground material pavements and a method for preparing the same.

[0007] In the first aspect, this application provides a surface concrete for special road materials, employing the following technical solution: A special type of surface concrete for road surfaces comprises the following raw materials in parts by weight: 380-420 parts silicate cement, 80-120 parts slag powder, 30-50 parts lithium slag powder, 650-720 parts steel slag sand, 980-1050 parts basalt crushed stone, 220-260 parts manufactured sand, 8.5-10.5 parts polycarboxylate high-performance water-reducing agent, 6-9 parts silica sol, and 100-140 parts water.

[0008] By adopting the above technical solution and using a synergistic activation system of highly active lithium slag powder and slag powder, in the alkaline environment of cement hydration, the active silica and alumina in the lithium slag powder react rapidly with the slag powder, continuously consuming the calcium hydroxide enriched and oriented in the interface region, thus significantly reducing its content. At the same time, a dense, high-strength and structurally stable CASH (hydrated calcium aluminum silicate gel) is generated, which can tightly wrap the aggregate, transforming the aggregate-slurry transition zone from a porous and loose weak link into a dense and strengthened zone. This solves the problem of surface peeling caused by weak interfacial bonding, effectively blocks the penetration of water and corrosive media, and improves the freeze-thaw resistance and erosion resistance of concrete. It is suitable for concrete for saline soil or concrete for ground surfaces in areas with extreme temperature differences.

[0009] The combination of high-wear-resistant steel slag sand and high-strength basalt crushed stone results in ultra-high skeleton strength. The steel slag sand itself is hard, wear-resistant, and porous, allowing it to bond tightly with the slurry. The basalt crushed stone provides ultra-high skeleton strength, and the introduced silica sol particles can fill the micropores in the cement and interface transition zone, further optimizing the pore structure and exerting a crystal nucleation effect. This promotes the densification of hydration products, improves the overall density and surface hardness of the surface concrete, and enhances wear resistance. At the same time, it can effectively resist the damage to the aggregate interface caused by sulfate crystallization pressure and ettringite expansion, preventing cracking around the aggregate. It has a long service life and good durability in saline soil environments or wet-dry cycle sulfate erosion environments.

[0010] Moreover, lithium slag powder and slag powder are both industrial wastes, which are abundant and inexpensive. They can partially replace cement, reduce material costs and carbon emissions. Nano-silica is introduced in the form of a sol, which is evenly dispersed and does not increase water demand. This avoids the problem of decreased workability caused by powder nanomaterials, and fresh concrete still maintains good construction performance.

[0011] Preferably, the surface concrete also contains 100-120 parts by weight of a wear-resistant modifier, which has a core-shell structure with carboxylated carbon nanotubes / TPU porous material as the core and silica / epoxy resin as the shell.

[0012] By adopting the above technical solutions, carboxylated carbon nanotubes / TPU porous materials can absorb energy through their own elastic compression deformation when concrete is subjected to impact or fatigue, passivate crack tips, and form bridging forces on the crack surface, thereby improving tensile toughness and fatigue life. When pore water freezes and causes volume expansion, it can absorb freeze-thaw energy through its own elastic deformation, alleviate the hydrostatic pressure of ice crystals on the pore walls, and reduce the probability of microcrack initiation. It has a very high toughening effect on repeated impacts of airport runways and heavy-duty pavements, improves the concrete's resistance to freeze-thaw cycles in environments with extreme temperature differences, and can also alleviate the internal tensile stress caused by drying shrinkage and temperature changes in concrete, reducing the probability of early shrinkage cracks in concrete.

[0013] The rigid shell, with silica as the skeleton, epoxy resin interpenetration, and short-cut carbon fiber reinforcement, gives the particles good surface hardness, thus solving the problem that the pure TPU particles are too soft, resulting in poor compressive strength and surface wear resistance of concrete.

[0014] Furthermore, the epoxy groups in the epoxy resin in the shell can undergo ring-opening reactions with cement hydration products in the alkaline environment of concrete to form chemical bonds, giving the interface between the wear-resistant additive particles and cement stone a chemically fused reinforced layer. At the same time, the toughness of the epoxy resin can buffer the modulus difference between the cement stone and the rigid shell, reducing the stress concentration at the interface.

[0015] Preferably, the method for preparing the wear-resistant modifier is as follows: Carboxymethyl carbon nanotubes / TPU porous material were added to anhydrous ethanol / deionized water mixed solution, and ammonia was added to adjust the pH to 8. Tetraethyl orthosilicate, epoxy resin emulsion and short-cut carbon fibers were added. After stirring and reacting for 10-12 hours, the mixture was filtered and dried at 80-100℃.

[0016] By adopting the above technical solution, the carboxyl groups on the surface of carboxylated carbon nanotubes in porous materials serve as highly active anchor points. In a weakly alkaline environment catalyzed by ammonia, they are partially deprotonated and strongly adsorb silica monomers generated by the hydrolysis of tetraethyl orthosilicate through hydroxyl groups or electrostatic interactions. This provides a template for the in-situ growth of silica on the porous material. During the hydrolysis and condensation of tetraethyl orthosilicate to form a Si-O-Si three-dimensional gel network, epoxy resin molecules are uniformly dispersed within it. As the condensation proceeds, the viscosity of the system increases, and the epoxy resin is in-situ locked in the three-dimensional pores of silica, forming an organic-inorganic interpenetrating network. Meanwhile, the chopped carbon fibers are uniformly dispersed during stirring and anchored within the shell by the gel network, playing a reinforcing role. Therefore, the chopped carbon fibers, epoxy resin, and silica serve as a shell, physically coating the core. Through the bonding between the carboxyl groups of carbon nanotubes and silica, an integrated shell that achieves in-situ growth, interpenetration, reinforcement, and anchoring is realized.

[0017] Furthermore, the silica in the shell provides high hardness, while the short-cut carbon fibers bear part of the frictional shear and prevent the shell from becoming brittle. During repeated tire wear, the shell itself exhibits excellent wear resistance, preventing the problem of pure TPU being easily torn out and leaving holes. The ends of some short-cut carbon fibers may protrude from the shell, forming fine mechanical anchors in the slurry, enhancing the shear resistance of the ions and cement. Even if the surface ion shell is worn away, the residual network of fibers and epoxy resin can still delay the overall shedding of particles, significantly reducing the formation of surface peeling pits and maintaining long-lasting anti-skid and wear-resistant effects.

[0018] Preferably, the mass ratio of the carboxylated carbon nanotubes / TPU porous material, tetraethyl orthosilicate, epoxy resin emulsion, and chopped carbon fibers is 1:0.8-1:0.2-0.25:0.04-0.08.

[0019] By adopting the above technical solution, carboxylated carbon nanotubes / TPU porous materials are used as the inner toughening core. Tetraethyl orthosilicate can form a rigid silica framework on the porous material. The above dosage can form a continuous framework layer with appropriate thickness, avoiding an excessively thin or incomplete shell layer, which would not be able to effectively seal the pores and provide rigidity. It also prevents the shell layer from being too thick, resulting in an excessively high overall particle modulus, which would weaken the toughening effect of the TPU core. Epoxy resin, as an organic toughening phase, forms an interpenetrating network with silica. If its dosage is too low, the toughening and interfacial adhesion improvement effects will not be obvious. If its dosage is too high, it will reduce the overall hardness and corrosion resistance of the shell layer. Short-cut carbon fibers enhance the crack resistance and wear resistance of the shell layer. If the dosage is too high, it is very easy to agglomerate or puncture the shell layer in the system, destroying the integrity of the coating.

[0020] Preferably, the surface concrete also contains 30-60 parts by weight of modified silicon nitride.

[0021] By adopting the above technical solution, silicon nitride is a self-lubricating material that can reduce the sliding resistance between friction surfaces, while increasing the internal density of concrete and improving compressive strength.

[0022] Preferably, the modified silicon nitride is prepared by the following method: Eight-aminoPOSS and polyvinyl alcohol are mixed, and silicon nitride treated with silane coupling agent is added. The mixture is then melted, extruded, and granulated to obtain a composite material. The composite material was soaked in glutaraldehyde solution, filtered, and dried to obtain composite particles. Aramid fibers are mixed with water-soluble epoxy resin emulsion, composite particles are added, the mixture is stirred evenly, and then dried at 65-80℃.

[0023] By adopting the above technical solution, the amino groups on the octaaminoPOSS readily form hydrogen bonds with the hydroxyl groups on the PVA molecular chain. The octaaminoPOSS acts as a physical cross-linking point, increasing the mobility and interaction forces of the PVA molecular chain, thus increasing the rigidity of the material. Furthermore, the octaaminoPOSS itself is a rigid particle, effectively reducing wear on polyvinyl alcohol. Silicon nitride has a high Mohs hardness, resisting cutting during surface wear, significantly enhancing the wear resistance of the composite particles. Moreover, the self-toughening matrix of silicon nitride can absorb crack propagation energy, improving fracture toughness. Immersion in glutaraldehyde solution allows it to penetrate into the composite material, preferentially reacting with polyvinyl alcohol. The hydroxyl groups undergo acetalization to form a dense surface cross-linked layer, which improves the surface hardness and elastic modulus of the particles, while the core maintains a relatively low cross-linking point to maintain toughness. The acetalization reaction consumes the free hydroxyl groups on polyvinyl alcohol, reducing water absorption, improving its water resistance, and enhancing its resistance to freeze-thaw cycles. Moreover, the highly cross-linked acetalization of the surface can increase the heat resistance temperature of polyvinyl alcohol, allowing quinones to maintain their form under high road surface temperatures in summer, without becoming sticky or softening. At the same time, the acetal bonds formed by glutaraldehyde cross-linking and the steric protection of the POSS cages ensure that the modified silicon nitride is stable in high-alkali and high-salt environments for a long time, without being decomposed or softened by sulfates, and continues to exert its toughening and crack-resistant effects.

[0024] Aramid fibers are uniformly wrapped around the surface of composite particles using water-soluble epoxy resin. After drying, the fibers and composite particles form a physical bond. When subjected to tire friction, the high-strength aramid fibers first withstand shearing and cutting, protecting the internal polymer matrix. The extremely high tensile strength and elongation at break of the aramid fibers can effectively bridge microcracks generated on the particle surface during wear, preventing the crack layer from expanding and causing the entire particle to peel off. Once freeze-thaw cycles induce microcracks, the bridging effect of the fibers can prevent them from expanding into through cracks, maintaining structural integrity. Moreover, after the aramid fibers on the surface of the composite particles are worn away, an extremely thin and tough fiber fluff layer can be formed at the interface between the particles and cement stone, providing a stable coefficient of friction while slowing down the wear rate of the matrix.

[0025] Preferably, the silica sol contains 25-35% silica and has a particle size of 15-25 nm.

[0026] Secondly, this application provides a method for preparing surface concrete for special road materials, using the following technical solution: A method for preparing surface concrete for special road materials includes the following steps: Silicate cement is mixed evenly with slag powder, lithium slag powder, steel slag sand, basalt crushed stone, and manufactured sand to obtain a semi-mixed material; Polycarboxylate superplasticizer and silica are dissolved and added to water, stirred evenly, and then semi-mixed and mixed evenly to obtain surface concrete.

[0027] By adopting the above technical solution, CASH gel is generated by the synergistic stimulation of lithium slag powder and slag powder, and ITZ densification is achieved with nano-silica to cut off the penetration channels of water and salt. Basalt crushed stone and steel slag sand are used as double hard aggregates, thereby improving the concrete's resistance to freezing, sulfate erosion and wear, and achieving a comprehensive improvement in high anti-slip, high wear resistance, high freezing resistance and high salt corrosion resistance.

[0028] In summary, this application has the following beneficial effects: 1. Because this application uses lithium slag powder and slag powder for activity matching and synergistic activation system, it reduces the calcium hydroxide content in the transition zone between cement and skeleton interface and generates dense CASH gel. Steel slag sand and basalt fragments are compounded to form a dual-hardness aggregate skeleton. Combined with nano silica sol to fill micropores, it reduces the ITZ of concrete and the porosity of the matrix, blocks the capillary connectivity, improves the overall density of the surface concrete, improves its compressive strength and wear resistance, and enhances its freeze-thaw resistance and sulfate erosion resistance.

[0029] 2. In this application, carboxylated carbon nanotubes / TPU porous materials are preferably used as the core, and silica, epoxy resin emulsion and short-cut carbon fibers are used to make the shell. This can obtain a wear-resistant modifier that is tough inside and hard outside. It can not only absorb deformation energy, enhance tensile toughness and fatigue life, but also improve the wear resistance of concrete surface, relieve freeze-thaw expansion pressure, avoid the generation of microcracks, and improve freeze-thaw resistance. It has a long service life under heavy traffic in extreme environments such as large temperature difference and saline soil.

[0030] 3. In this application, octaaminoPOSS, PVA and aramid fiber are preferred to pretreat silicon nitride to further improve the uniformity of silicon nitride dispersion in concrete and simultaneously improve the crack resistance of concrete. This avoids the impact of adding silicon nitride alone on the crack resistance of concrete, while improving the long-term stability in high-alkali and high-salt environments and continuously exerting toughening and crack resistance functions. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the embodiments.

[0032] Example 1: Preparation of carboxylated carbon nanotube / TPU porous material: 64g of carboxylated carbon nanotubes were added to a mixture of 1,4-dioxane / deionized water (volume ratio 95:5), and ultrasonically treated for 1h to obtain a dispersion. 32g of TPU was added to the dispersion, stirred at 60℃ for 100min, kept at 0 speed for 30min, kept at -20℃ for 48h, and vacuum dried at -50℃ for 72h. The TPU was selected from BASF, Germany, model 1185A, and the carboxylated carbon nanotubes were selected from CNT305.

[0033] Example 2 of preparation of wear-resistant modifier: 100g of carboxylated carbon nanotube / TPU porous material prepared in Example 1 was added to anhydrous ethanol / deionized water (volume ratio of 10:1), the pH was adjusted to 8 with ammonia, 100g of tetraethyl orthosilicate, 25g of epoxy resin emulsion and 8g of short carbon fibers were added, the mixture was stirred and reacted for 12h, filtered and dried at 100℃. The epoxy resin emulsion was prepared by epoxy resin and curing agent in a mass ratio of 10:1. The epoxy resin was selected from E-44 type epoxy resin, the curing agent was polyamide 650, and the length of the short carbon fibers was 5mm.

[0034] Example 3 of preparation of wear-resistant modifier: 100g of carboxylated carbon nanotube / TPU porous material prepared in Example 1 was added to anhydrous ethanol / deionized water (volume ratio of 10:1), the pH was adjusted to 8 with ammonia, 80g of tetraethyl orthosilicate, 20g of epoxy resin emulsion and 4g of short carbon fibers were added, the mixture was stirred and reacted for 10h, filtered and dried at 80℃. The epoxy resin emulsion was prepared by epoxy resin and curing agent in a mass ratio of 10:1. The epoxy resin was selected from E-44 type epoxy resin, the curing agent was polyamide 650, and the short carbon fiber length was 5mm.

[0035] Example 4 of the preparation of wear-resistant modifier: The difference from Example 2 is that no epoxy resin emulsion was added.

[0036] Example 5 of the preparation of wear-resistant modifier: The difference from Example 2 is that tetraethyl orthosilicate was not added.

[0037] Example 6 of the preparation of wear-resistant modifier: The difference from Example 2 is that short-cut carbon fibers were not added.

[0038] Example 7 of the preparation of octaaminoPOSS: 40.628 g of coupling agent KH550 was mixed with 28.414 g of deionized water and 118.96 g of tetrahydrofuran. 6 drops of hydrochloric acid were added dropwise at 60 °C. After reacting at a constant temperature for 72 h, the product was introduced into an equal amount of tetrahydrofuran to obtain a white precipitate. The product was repeatedly washed with tetrahydrofuran to remove unreacted raw materials and hydrochloric acid. It was then vacuum dried at 60 °C and ground to obtain octaaminoPOSS.

[0039] Example 8 of the preparation of modified silicon nitride: 2g of octaaminoPOSS prepared in Example 7 and 100g of polyvinyl alcohol were mixed evenly, and silicon nitride pretreated with silane coupling agent KH550 was added. The mixture was melted, extruded and granulated at 165°C to obtain a composite material. The polyvinyl alcohol was selected from Kuraray, Japan, and the model was PVA-117. The composite material was soaked in a 3 wt% glutaraldehyde solution for 8 hours, then filtered and dried to obtain composite particles. Mix 100g of aramid fiber with 20g of water-soluble epoxy resin emulsion, add 60g of composite particles, stir evenly, and dry at 80℃. The length of the aramid fiber is 10mm.

[0040] Example 9 of the preparation of modified silicon nitride: 2g of octaaminoPOSS prepared in Preparation Example 7 and 100g of polyvinyl alcohol were mixed evenly, and silicon nitride pretreated with silane coupling agent KH550 was added. The mixture was melted, extruded and granulated at 165°C to obtain modified silicon nitride. The polyvinyl alcohol was selected from Kuraray, Japan, and the model was PVA-117.

[0041] Example 10 of the preparation of modified silicon nitride: 2g of octaaminoPOSS prepared in preparation example 7 and 100g of polyvinyl alcohol were mixed evenly, and silicon nitride pretreated with silane coupling agent KH550 was added. The mixture was melted, extruded and granulated at 165°C to obtain a composite material. The polyvinyl alcohol was selected from Kuraray, Japan, and the model was PVA-117. The composite material was soaked in a 3 wt% glutaraldehyde solution for 8 hours, then filtered and dried to obtain modified silicon nitride.

[0042] Example 11 of the preparation of modified silicon nitride: 2g of octaaminoPOSS prepared in preparation example 7 and 100g of polyvinyl alcohol were mixed evenly, and silicon nitride pretreated with silane coupling agent KH550 was added. The mixture was melted, extruded and granulated at 165°C to obtain a composite material. The polyvinyl alcohol was selected from Kuraray, Japan, and the model was PVA-117. Mix 100g of aramid fiber with 20g of water-soluble epoxy resin emulsion, add 60g of composite material, stir evenly, and dry at 80℃. The length of the aramid fiber is 10mm. Example

[0043] Example 1: A special type of surface concrete for road surfaces, the raw material quantities are shown in Table 1, wherein the silicate cement is P·II52.5 cement, and the specific surface area of ​​the slag powder is 450 m². 2 / kg, lithium slag powder fineness 45μm sieve residue rate 10%, steel slag sand crushing value particle size 3mm, crushing value ≤12%, basalt crushed stone particle size 10mm, crushing value ≤10%, needle-like and flaky content ≤5%, manufactured sand particle size 2mm, polycarboxylate high-performance water reducing agent selected from Shandong Yonglida, product number YLD-05, model YLD-JSSFT, silica sol is formed by silica particles dispersed in water, solid content is 25%, silica particle size is 20nm.

[0044] The preparation method of the above-mentioned special-grade pavement surface concrete includes the following steps: Silicate cement is mixed evenly with slag powder, lithium slag powder, steel slag sand, basalt crushed stone, and manufactured sand to obtain a semi-mixed material; Polycarboxylate superplasticizer and silica are dissolved and added to water, stirred evenly, and then semi-mixed and mixed evenly to obtain surface concrete.

[0045] Table 1. Raw material consumption of surface concrete in Examples 1-7

[0046] Examples 2-4: A special type of surface concrete for road surfaces, which differs from Example 1 in that the raw material quantities are shown in Table 1.

[0047] Example 5: A special type of surface concrete for road surface, which differs from Example 1 in that 100 kg of wear-resistant modifier is added to the dry mix. The wear-resistant modifier is prepared by Example 2.

[0048] Example 6: A special type of surface concrete for road surface, which differs from Example 1 in that 100 kg of wear-resistant modifier is added to the dry mix. The wear-resistant modifier is prepared by Example 3.

[0049] Example 7: A special type of surface concrete for road surface, which differs from Example 5 in that 100 kg of wear-resistant modifier is added to the dry mix. The wear-resistant modifier is prepared by Example 4.

[0050] Example 8: A special type of surface concrete for road surface, which differs from Example 5 in that 100 kg of wear-resistant modifier is added to the dry mix. The wear-resistant modifier is prepared by Example 5.

[0051] Example 9: A special type of surface concrete for road surface, which differs from Example 5 in that 100 kg of wear-resistant modifier is added to the dry mix. The wear-resistant modifier is prepared by Example 6.

[0052] Example 10: A special type of surface concrete for road surface, which differs from Example 5 in that 100 kg of wear-resistant modifier is added to the dry mix. The wear-resistant modifier is a carboxylated carbon nanotube / TPU porous material, prepared from Preparation Example 1.

[0053] Example 11: A special type of surface concrete for road surface, which differs from Example 5 in that 60 kg of modified silicon nitride is added to the dry mix. The modified silicon nitride is prepared by Example 8.

[0054] Example 12: A special type of surface concrete for road surface, which differs from Example 11 in that 60 kg of modified silicon nitride is added to the dry mix. The modified silicon nitride is prepared by Example 9.

[0055] Example 13: A special type of surface concrete for road surface, which differs from Example 11 in that 60 kg of modified silicon nitride is added to the dry mix. The modified silicon nitride is prepared by Example 10.

[0056] Example 14: A special type of surface concrete for road surface, which differs from Example 11 in that 60 kg of modified silicon nitride is added to the dry mix. The modified silicon nitride is prepared in Example 11.

[0057] Comparative Example Comparative Example 1: A special type of surface concrete for road surface, which differs from Example 11 in that lithium slag powder and slag powder are not added.

[0058] Comparative Example 2: A special type of surface concrete for road surface, which differs from Example 11 in that it does not contain steel slag sand.

[0059] Performance testing The surface concrete was prepared according to the methods in the examples and comparative examples, and its performance was tested according to the following methods. The test results are recorded in Table 2.

[0060] 1. Compressive strength and splitting tensile strength: Tested in accordance with GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0061] 2. Abrasion Value: The specimen is placed on the testing machine fixture, and a certain load is applied to it. Then, the grinding disc rotates uniformly around its central axis at a certain speed, causing the abrasive on it to rub against the surface of the specimen. The abrasion value per unit area of ​​the specimen is calculated as an evaluation index of the abrasion resistance of concrete. Main parameters: Grinding disc diameter: 52.5cm; Grinding disc speed: 32r / min; Test load: provided by weights, load 4.1Kg; Test abrasive: 0.5mm brown corundum is used, and the abrasive can be reused 3 times; Test speed: Before the test, the specimen is ground for 30 revolutions to remove surface laitance, and then ground for 100 revolutions.

[0062] Test procedure: 1. Measure the diameter of each specimen to an accuracy of 0.05 mm, and take the arithmetic mean of three measurements at different locations as the final measurement result; 2. Grind the specimen for 30 revolutions to remove the surface slurry, then clean, dry (dry in an oven at about 40°C for 0.5 hours) the specimen and weigh it (G1); 3. Place the two specimens in the fixtures respectively, add weights, start the motor, and rotate the grinding disc at a speed of 32 r / min. Then adjust the throttle valve to allow the abrasive to fall evenly from the funnel onto the grinding disc at a speed of 0.5 L / min. During the grinding process, the specimens are fixed in the fixtures and do not move. The grinding disc rotates, driving the abrasive on the grinding disc to grind the specimens. 4. When the grinding speed reaches 100 revolutions per minute, turn off the motor, remove the specimen, clean and dry it (dry in an oven at approximately 40°C for 0.5 hours), and weigh it (G2). Calculation of test results: R = (G1 - G2) / A; Where: R - abrasion value, kg / m 2 G1 - Specimen mass before grinding, kg; G2 - Specimen mass after grinding, kg; A - Specimen surface area subjected to grinding, m² 2 ; 4. Freeze-thaw resistance: Tested in accordance with GB / T50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete".

[0063] 5. Road surface perforation value: The test shall be conducted in accordance with JTG E60-2008 "Specifications for Testing Existing Road Subgrade and Pavement".

[0064] Table 2 Performance test results of surface concrete for special road materials

[0065] Based on the data in Table 2 and the raw material usage in Examples 1-4, it can be seen that the surface concrete prepared using slag powder, lithium slag powder, steel slag sand and basalt crushed stone has the advantages of high anti-slip and wear resistance, high strength and strong frost resistance.

[0066] Compared with Example 1, Examples 5 and 6 also added wear-resistant modifiers. Table 2 shows that the surface concrete prepared in Examples 5 and 6 has increased compressive strength and splitting tensile strength, enhanced wear resistance, improved anti-slip ability, reduced freeze-thaw loss, and improved freeze-thaw resistance.

[0067] Compared to Example 5, Example 7 used the wear-resistant modifier prepared in Preparation Example 4. Compared to Preparation Example 2 in Example 5, no epoxy resin emulsion was used. The data in Table 2 show that the concrete prepared in Example 7 has a decreased splitting tensile strength, weakened wear resistance, and decreased freeze-thaw resistance.

[0068] In Example 8, the wear-resistant modifier prepared in Preparation Example 5 was used. Compared with Preparation Example 2, Preparation Example 5 did not contain tetraethyl orthosilicate. Compared with Example 1, the surface concrete prepared in Preparation Example 8 had reduced compressive strength, decreased wear resistance, and weakened freeze-thaw resistance.

[0069] Compared to Example 1, Example 9 used the wear-resistant modifier prepared in Preparation Example 6, which did not contain short-cut carbon fibers. Therefore, the anti-slip and wear-resistant properties of the surface concrete prepared in Example 9 decreased. Compared with Example 1, Example 10 uses carboxylated carbon nanotubes / TPU porous materials as wear resistance modifiers. The data in Table 2 shows that although the splitting tensile strength of concrete increased, its wear resistance decreased significantly, and its freeze-thaw resistance also weakened. This indicates that using only carboxylated carbon nanotubes / TPU porous materials cannot effectively improve the wear resistance and freeze-thaw resistance of concrete.

[0070] Compared with Example 5, Example 11 also added modified silicon nitride prepared in Preparation Example 8. The data in Table 2 show that the compressive strength and wear resistance of the surface concrete prepared in Example 11 were further improved.

[0071] Compared to Example 11, Example 12 uses modified silicon nitride prepared in Preparation Example 9. In Preparation Example 9, silicon nitride was blended and granulated with polyvinyl alcohol and octaaminoPOSS. As can be seen from the data in Table 2, the compressive strength and wear resistance of the surface concrete prepared in Example 12 decreased.

[0072] In Example 13, modified silicon nitride prepared in Preparation Example 10 was used, while in Example 14, modified silicon nitride prepared in Preparation Example 11 was used. As can be seen from the data comparison in Table 2, the wear resistance of the surface concrete prepared in Examples 13 and 14 decreased.

[0073] Compared with Example 1, Comparative Example 1 did not add slag powder and lithium slag powder, and the resulting concrete had significantly reduced compressive strength and weakened wear resistance.

[0074] Compared with Example 1, Comparative Example 2 did not add steel slag sand. The surface concrete prepared in Comparative Example 2 had increased wear, decreased wear resistance, weakened anti-slip properties, and decreased compressive strength.

[0075] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A special type of surface concrete for road surfaces, characterized in that, The raw materials include the following parts by weight: 380-420 parts silicate cement, 80-120 parts slag powder, 30-50 parts lithium slag powder, 650-720 parts steel slag sand, 980-1050 parts basalt crushed stone, 220-260 parts manufactured sand, 8.5-10.5 parts polycarboxylate high-performance water-reducing agent, 6-9 parts silica sol, and 100-140 parts water.

2. The special-grade concrete surface layer for road surfaces according to claim 1, characterized in that: The surface concrete also contains 100-120 parts by weight of wear-resistant modifier, which has a core-shell structure with carboxylated carbon nanotubes / TPU porous material as the core and silica / epoxy resin as the shell.

3. The surface concrete for special road materials according to claim 2, characterized in that: The method for preparing the wear-resistant modifier is as follows: Carboxymethyl carbon nanotubes / TPU porous material were added to anhydrous ethanol / deionized water mixed solution, and ammonia was added to adjust the pH to 8. Tetraethyl orthosilicate, epoxy resin emulsion and short-cut carbon fibers were added. After stirring and reacting for 10-12 hours, the mixture was filtered and dried at 80-100℃.

4. The surface concrete for special road materials according to claim 3, characterized in that: The mass ratio of the carboxylated carbon nanotubes / TPU porous material, tetraethyl orthosilicate, epoxy resin emulsion, and chopped carbon fibers is 1:0.8-1:0.2-0.25:0.04-0.

08.

5. The surface concrete for special road materials according to claim 1, characterized in that: The surface concrete also contains 30-60 parts by weight of modified silicon nitride.

6. The surface concrete for special road materials according to claim 5, characterized in that: The modified silicon nitride is prepared by the following method: Eight-aminoPOSS and polyvinyl alcohol are mixed, and silicon nitride treated with silane coupling agent is added. The mixture is then melted, extruded, and granulated to obtain a composite material. The composite material was soaked in glutaraldehyde solution, filtered, and dried to obtain composite particles. Aramid fibers are mixed with water-soluble epoxy resin emulsion, composite particles are added, the mixture is stirred evenly, and then dried at 65-80℃.

7. The surface concrete for special road materials according to claim 1, characterized in that: The silica sol contains 25-35% silica and has a particle size of 15-25 nm.

8. The method for preparing surface concrete for special road materials as described in any one of claims 1-7, characterized in that, Includes the following steps: Silicate cement is mixed evenly with slag powder, lithium slag powder, steel slag sand, basalt crushed stone, and manufactured sand to obtain a semi-mixed material; Polycarboxylate superplasticizer and silica are dissolved and added to water, stirred evenly, and then semi-mixed and mixed evenly to obtain surface concrete.

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