Iron-silicate abrasion-resistant surface layer and construction method thereof

Abstract

The invention discloses an iron-silicate abrasion-resistant surface layer and a construction method thereof.The abrasion-resistant surface layer is a uniform mixture of iron powder, cement, water, fine aggregate, coarse aggregate and an exciting agent, the surface of hydraulic concrete is evenly covered with the uniform mixture, a neodymium magnet wrapped by geotechnical cloth is adopted for trowelling, and hydrothermal curing is conducted for 12-24 h; under the hydrothermal curing condition and the action of the exciting agent, the iron powder and the silicate material are subjected to contact hardening through a condensation polymerization reaction, and the iron powder and a hydration product of the silicate material jointly form an integral abrasion-resistant protective surface layer. The anti-abrasion surface layer can effectively improve the suspended load abrasion resistance of the hydraulic concrete. According to the iron-silicate anti-abrasion surface layer and the construction method thereof, the surface hardness of the hydraulic concrete can be effectively improved, the anti-abrasion capacity of the concrete is remarkably improved, the service life of the hydraulic concrete is prolonged, the later-stage secondary maintenance cost of the hydraulic concrete is reduced, and the manufacturing method is simple, convenient and suitable for new and old hydraulic concrete structures.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic concrete materials and relates to a method for preparing an abrasion-resistant hydraulic concrete surface layer. Background Art

[0002] Abrasion resistance is one of the most important properties of hydraulic concrete structures. Erosion, abrasion, and cavitation damage are common problems in hydraulic structures, affecting not only their durability but also their operational safety.

[0003] Currently, the main methods for improving the abrasion resistance of concrete are: 1. Increasing the concrete's strength grade; 2. Adding active admixtures such as silica fume and fly ash to improve particle packing; and 3. Adding materials such as fibers and rubber particles to improve concrete toughness. When improvements to the concrete's inherent abrasion resistance are limited, adding a wear-resistant surface layer to its surface is a common approach to enhance the overall abrasion resistance of hydraulic concrete structures. Commonly used protective surface layers for hydraulic concrete include stainless steel plates, slate, cast stone, epoxy resin, and polyurea. These materials each have their own advantages and disadvantages, with the main drawbacks currently manifesting as: 1) weak bonding with the base concrete. While some materials such as resins and polyurea have good inherent wear resistance, they struggle to blend with concrete and can be easily dislodged. 3. Difficulty maintaining integrity. Materials such as slate and steel plates struggle to maintain integrity, exhibit joints, and are easily washed away by high-speed water pressure.

[0004] Prior art, invention patent CN 117567176A discloses a method for forming an anti-abrasion and anti-corrosion protective layer from a mixture of mineral fillers and metals using low-temperature melting technology, thereby improving the abrasion resistance of hydraulic concrete. This invention primarily utilizes silicon dioxide, potassium oxide, and aluminum oxide, forming a 1mm to 5mm thick, ceramic-like protective layer at 85°C to 120°C. The layer exhibits high hardness and an interfacial bond strength of up to 6MPa. The process is complex, requiring a flame spray gun, maintained at 90°C, and sintering for 30 minutes.

[0005] Invention patent CN 103043955A discloses a high-strength, abrasion-resistant concrete formula using iron ore as coarse and fine aggregate. This formula, characterized by the use of iron ore as coarse and fine aggregate without the addition of fly ash or expansion agents, improves the concrete's flexural and compressive strengths, resulting in superior abrasion resistance compared to high-performance steel fiber reinforced concrete. This invention primarily leverages the excellent wear resistance of the iron ore itself to enhance abrasion resistance. The iron ore does not react with the cementitious material and serves solely as an aggregate filler.

[0006] Invention patent CN 103739248 discloses a reinforced quick-drying cement mortar made from iron powder, styrene-butadiene emulsion, and fiber. The mortar's crack resistance is significantly improved. However, the improvements in mortar strength and abrasion resistance are limited, as the iron powder primarily acts as a filler and does not participate in the reaction.

[0007] Invention patent CN 109879651A discloses a highly durable, impact-resistant, ultra-high-strength concrete made from high-iron sulfoaluminate cement, silica fume, metakaolin, steel fiber, and iron slag balls. This invention primarily increases concrete strength and improves its impact and abrasion resistance by increasing its density. The iron slag balls serve primarily as filler and do not participate in the reaction.

[0008] Invention patent CN 110330294A discloses a Portland cement mortar reinforced with iron ore, nanomaterials, fibers, and rubber powder, resulting in high impact toughness, high bond strength, low shrinkage, and high crack resistance. The invention primarily uses nanomaterials to increase the density of the mortar, while the iron ore serves primarily as a filler and does not participate in the reaction.

[0009] Invention patent CN 110304881A discloses a crack-resistant, highly impact-resistant repair material. The repair material primarily comprises cement, nanomaterials, fibers, iron ore, and organic polymers, forming a spatial network structure of aggregate-polymer film-cement stone, which reduces shrinkage and deformation and improves crack resistance. Iron ore is used as the wear-resistant aggregate.

[0010] Invention patent CN 116477894A discloses a wear-resistant ultra-high-performance concrete and its preparation method. The concrete materials described primarily include high-iron-phase Portland cement, fly ash, silica fume, sand, steel fiber, modified rubber particles, modified graphene oxide, an expansive agent, a water reducer, and water. The high-iron-phase Portland cement primarily results from a high content of tetracalcium aluminoferrite, one of the four major minerals in Portland cement.

[0011] The main idea of the existing technology is to use high-hardness materials as fillers, using their wear resistance to improve the overall wear resistance of concrete, or to use cement with high tetracalcium aluminoferrite content to prepare concrete, both of which can improve the concrete's anti-abrasion performance to a certain extent.

[0012] However, the existing technology still has two defects. First, the overall wear resistance of concrete is changed by using high-hardness materials or special cements, but it is the concrete surface that actually bears the impact and wear. For example, only the surface of about 20 cm of a 1-meter-thick impact-resistant base plate is subject to impact and wear damage. Improving the overall wear resistance of concrete will cause some material waste and increase costs. On the other hand, if a special wear-resistant layer is applied separately on the surface of the concrete, the surface will be debonded and damaged due to the large difference in properties between the wear-resistant layer and the base concrete. Summary of the Invention

[0013] In order to overcome the above-mentioned defects, the present invention proposes an iron-silicate anti-impact and wear surface layer and its preparation method, which forms a natural transition gradient inside the concrete through a magnetic field, completes a smooth transition between the surface layer and the base concrete, and at the same time can significantly improve the impact and wear resistance of the surface layer.

[0014] As a hydraulic structure's abrasion-resistant component, it's crucial to improve the wear resistance of the concrete surface while avoiding significant differences in surface and interior concrete properties, which can lead to significant delamination and inconsistent deformation. The present invention provides an iron-silicate abrasion-resistant surface layer and its construction method. Under the action of an activator, iron powder and silicate undergo a polycondensation reaction and contact hardening to form a high-hardness, high-strength abrasion-resistant protective surface layer. This protective surface layer can be integrated with the hydraulic concrete to form a single unit, exhibiting excellent overall performance and significantly improving the abrasion resistance of the hydraulic concrete surface.

[0015] The technical solution adopted in the present invention is: The present invention provides a method for preparing and constructing an iron-silicate surface layer for improving the anti-abrasion performance of hydraulic concrete. The preparation method and construction method of the iron-silicate anti-abrasion surface layer include surface layer material components, surface layer material combination ratios, and specific surface layer construction and application methods.

[0016] The surface layer material is composed of a mixture of iron powder, cement, water, fine aggregate, coarse aggregate and activator, and the components in the mixture are mixed in the following mass proportions: 15-60 parts of iron powder, 300-500 parts of cement, 130-150 parts of water, 600-800 parts of fine aggregate, 800-1200 parts of coarse aggregate and 10-15 parts of activator; the mixture is stirred evenly and poured on the concrete surface, and smoothed with a neodymium magnet wrapped in geotextile. Under the action of the magnetic field, the iron powder will be enriched on the concrete surface, forming a continuous transition structure with a gradient of iron powder content decreasing from the surface to the inside; hydrothermal curing is carried out at 45°C-60°C for 12h-24h, so that the silicate in the cement undergoes a hydration reaction and the iron powder undergoes a contact hardening reaction under the action of the activator, thereby jointly forming an impact-resistant surface layer.

[0017] Preferably, the fine aggregate is one of natural sand and quartz sand, with a particle size of 0.075-4.75 mm and good gradation.

[0018] The coarse aggregate is basalt crushed stone with a particle size of 5 to 40 mm and good gradation.

[0019] The iron powder is conventional iron powder with a fineness of 250~350 mesh.

[0020] The activator is a highly alkaline silicate solution; Preferably, the activator is a high alkaline silicate solution with a pH>13; The activator is a high-alkaline sodium silicate solution, which is prepared by adjusting the modulus of industrial water glass with solid sodium hydroxide. The pH is greater than 13, and the modulus is controlled at 1.0~2.0. The components are mixed in the following mass proportions: 60~80 parts of water, 10~20 parts of solid sodium hydroxide, and 800~1000 parts of industrial water glass.

[0021] Preferably, the components in the mixture are mixed in the following mass ratios: 30~50 parts of iron powder, 350~400 parts of cement, 130~135 parts of water, 650~700 parts of fine aggregate, 1000~1200 parts of coarse aggregate, and 13~15 parts of activator.

[0022] More preferably, the components in the mixture are mixed in the following mass ratios: 50 parts of iron powder, 350 parts of cement, 130 parts of water, 660 parts of fine aggregate, 1000 parts of coarse aggregate and 13.5 parts of activator were mixed to obtain a reactive mixture.

[0023] The activator is preferably a high alkaline sodium silicate solution, which is prepared by adjusting the modulus of industrial water glass with solid sodium hydroxide, with a pH of 14 and a modulus of 1.5.

[0024] The present invention provides a method for constructing an iron-silicate anti-wear surface layer, which comprises the following specific steps: Step 1: Weigh each component material in proportion; Step 2: Mix and stir evenly to prepare an iron-silicate anti-impact and wear surface layer material; Step 3: Evenly cover the concrete surface with the material prepared in step 2 by 20mm~50mm; Step 4: Use geotextile wrapped with neodymium magnets to smooth the anti-wear surface layer, ensuring good adhesion between the bottom and the concrete specimen to form a whole; Step 5: Hydrothermal curing at 45℃~60℃ for 12h~24h.

[0025] More preferably, step 5 is hydrothermal curing at 60° C. for 24 hours.

[0026] Principle of the Invention: This invention utilizes the contact-hardening properties of metal and silicate materials under the action of a high-temperature, highly alkaline silicate solution. Under the action of an activator, metal silicates are formed, and their high hardness provides impact and wear resistance. By adding neodymium magnets during the finishing process, iron powder is concentrated on the surface under the influence of the magnetic field. However, unlike directly sprinkling iron powder on the surface, the process described in this invention avoids delamination caused by a significant difference in the properties of the surface and underlying concrete. The gradient structure of the iron powder content further improves iron powder utilization.

[0027] Compared to the high-performance, high-strength, impact-resistant and wear-resistant concrete materials in the prior art, the present invention uses external iron powder and a high-temperature, high-alkali environment to promote a contact hardening reaction between the iron powder and silicate, forming a high-hardness metal silicate to enhance impact and wear resistance. This is significantly different from the traditional practice of using iron materials as fillers. Compared to the prior art scheme that mainly uses epoxy resin to prepare impact-resistant and wear-resistant mortar to provide impact and wear resistance for concrete, the present invention utilizes the condensation reaction of silicate and the contact hardening of metal and silicate to form a high-strength, high-hardness impact-resistant and wear-resistant protective surface layer. There is a significant difference in the mechanism. The material used in the present invention is closer to the mechanical properties, deformation properties, and thermal properties of the base concrete.

[0028] Beneficial effects:

[0029] Compared with the existing hydraulic concrete anti-abrasion technology, the present invention has the following advantages: (1) The iron-silicate anti-abrasion surface layer and its construction method provided by the present invention can significantly improve the anti-abrasion performance of concrete, which belongs to improving the external anti-abrasion ability of concrete and can further improve the anti-abrasion ability of concrete after the anti-abrasion performance of concrete itself is improved; (2) The construction method of the present invention is simple, the surface layer and the concrete have similar properties, are directly combined into a whole, have strong coordination, and are not prone to debonding and stratification during temperature changes, humidity changes, and stress changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of iron-silicate anti-wear surface layer applied to newly built hydraulic concrete, where 1-neodymium magnet, 2-geotextile, 3-iron powder, 4-protective matrix. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. The specific embodiments described here are only used to explain the technical solutions of the present invention.

[0032] Example 1

[0033] See also Figure 1 As shown, this embodiment provides an iron-silicate anti-wear surface layer and a construction method thereof for use on newly built hydraulic concrete, including the preparation and application of the anti-wear surface layer.

[0034] The implementation steps are: Step 1: Prepare a concrete specimen as the protective matrix 4 of the protective material in accordance with the specification requirements (there is no requirement for the mix ratio of concrete for this patent). In this embodiment, the concrete specimen is C60 concrete prepared using ordinary Portland cement according to the mix ratio in Table 1, with a curing age of 28 days; Step 2: Prepare the impact-resistant surface layer material by mixing 50 parts iron powder, 350 parts cement, 130 parts water, 660 parts fine aggregate, 1000 parts coarse aggregate, and 13.5 parts activator to form a reactive mixture. The activator is a highly alkaline sodium silicate solution, prepared by adjusting the modulus of industrial water glass with solid sodium hydroxide. The solution has a pH of 14 and a modulus of 1.5. It contains 70 parts water, 15 parts solid sodium hydroxide, and 900 parts industrial water glass.

[0035] The cement used is P·O42.5 cement; The coarse aggregate is basalt crushed stone with a particle size of 5 to 40 mm and good gradation; Fine aggregate is a type of quartz sand with a particle size of 0.075~4.75mm and good gradation; The iron powder is conventional iron powder with a fineness of 250-350 mesh; Step 3: Evenly cover the concrete surface with the material prepared in step 2 by 50mm; Step 4: Geotextile 2 wraps neodymium magnet 1 to smooth the anti-wear surface layer, iron powder 3 is enriched on the surface, and the bottom is well bonded with the concrete specimen to form a whole, such as Figure 1 As shown; Step 5: Hydrothermal curing at 60℃ for 24h.

[0036] Table 1 Concrete mix ratio (kg / m 3 ) Water-cement ratio Water consumption cement fly ash silica fume sand Xiaoshi Zhongshi Water reducing agent (%) Air-entraining agent (‱) 0.32 136 276 128 21 611 518 776 1.1 2.7 After curing, the thickness of the anti-wear surface layer is 18mm. The surface hardness is 850HV when tested by microhardness tester, and the interface bonding strength is 5.5MPa when tested by pull-off tester. The anti-wear performance is tested by high-speed underwater steel ball method with the speed set at 4000rpm. The 28d anti-wear strength is 21.34 (h·m 2 / kg), the 28d abrasion resistance of the C60 concrete in step 1 is 3.52 (h·m 2 / kg), the surface layer of the present invention has a much higher abrasion resistance than the reference concrete. The synergistic effect of the various material components of the present invention is independent of the abrasion resistance of the reference concrete in step 1.

[0037] Example 2

[0038] This embodiment provides an iron-silicate anti-wear surface layer and a construction method thereof The implementation steps are: Step 1: Prepare hydraulic abrasion-resistant concrete specimens according to the specifications and cure for 28 days; Step 2: Prepare the anti-wear surface layer material by mixing 50 parts of iron powder, 400 parts of cement, 130 parts of water, 660 parts of fine aggregate, 920 parts of coarse aggregate, 13.5 parts of activator, pH=14 to obtain a reactive mixture; The cement used is P·O42.5 cement; The coarse aggregate is basalt crushed stone with a particle size of 5~40mm and good gradation; Fine aggregate is a type of quartz sand with a particle size of 0.075~4.75mm and good gradation; The iron powder is conventional iron powder with a fineness of 250-350 mesh; The activator is a high-alkaline sodium silicate solution, which is prepared by adjusting the modulus of industrial water glass with solid sodium hydroxide. The pH is 14, the modulus is 1.0, and the solution contains 60 parts of water, 20 parts of solid sodium hydroxide, and 800 parts of industrial water glass.

[0039] Step 3: Evenly cover the mixture slurry obtained in step 2 on the concrete specimen by 15 mm to ensure uniform coverage of the material.

[0040] Step 4: Use neodymium magnets wrapped in geotextiles to level the surface, perform hydrothermal curing for 24 hours at 60°C, and then naturally cure for 28 days; Step 5: After curing, the concrete and the abrasion-resistant surface layer form a whole with good interface bonding performance. The results are shown in Table 2.

[0041] Example 3

[0042] This embodiment is the same as Example 2, except that the components of the impact-resistant surface layer material in step 2 are different. This embodiment uses 40 parts of iron powder, 400 parts of cement, 130 parts of water, 660 parts of fine aggregate, 1050 parts of coarse aggregate, and 15 parts of activator to mix to obtain a reactive mixture. The activator has a pH of 13.5, a modulus of 1.5, 70 parts of water, 15 parts of solid sodium hydroxide, and 900 parts of industrial water glass.

[0043] Example 4

[0044] This embodiment is the same as Example 2, except that the components of the impact-resistant surface layer material in step 2 are different. This embodiment uses 50 parts of iron powder, 400 parts of cement, 135 parts of water, 700 parts of fine aggregate, 1100 parts of coarse aggregate, and 13.5 parts of activator to mix to obtain a reactive mixture. The activator has a pH of 14, a modulus of 1.0, 60 parts of water, 20 parts of solid sodium hydroxide, and 800 parts of industrial water glass.

[0045] Comparative Example 1 This control example is the same as Example 2, except that the components of the impact-resistant surface layer material in step 2 are different. In this control example, 400 parts of cement, 130 parts of water, 660 parts of fine aggregate, 920 parts of coarse aggregate, and 13.5 parts of activator are mixed to obtain a reactive mixture.

[0046] Comparative Example 2 This control example is the same as Example 2, except that the components of the impact-resistant surface layer material in step 2 are different. In this control example, 50 parts of iron powder, 400 parts of cement, 130 parts of water, 660 parts of fine aggregate, and 920 parts of coarse aggregate are mixed to obtain a reactive mixture. No activator is used, and the mixture is hydrothermally cured for 24 hours at a temperature of 60°C, and then naturally cured for 28 days.

[0047] Comparative Example 3 This control example is the same as steps 1 to 3 of Example 2, except that step 4 is different. Conventional methods are used for leveling, hydrothermal curing is performed for 24 hours at a temperature of 60°C, and then natural curing is performed for 28 days.

[0048] Comparative Example 4 This control example is the same as control example 3, except that the components of the impact-resistant surface layer material are different. In this control example, 50 parts of iron powder, 500 parts of cement, 130 parts of water, 660 parts of fine aggregate, 920 parts of coarse aggregate, and 13.5 parts of activator are mixed to obtain a reactive mixture; and the mixture is naturally cured for 28 days.

[0049] After adding iron powder in Examples 1 to 4, the surface hardness, impact resistance and compressive strength of the anti-wear surface layer are significantly improved compared with those in Control Example 1, and metal silicate is formed on the surface of the anti-wear surface layer, thereby having high hardness and improving impact resistance and wear resistance; after adding 13.5 parts of activator, the impact resistance and wear resistance are also significantly improved compared with Control Example 2, which is because the metal and silicate materials have contact hardening characteristics under the action of highly alkaline silicate solution, forming metal silicate; Examples 1 to 4 are all smoothed with neodymium magnets wrapped in geotextiles, and the surface hardness and bonding strength are significantly improved compared with the control example, which is because the iron powder is enriched to the surface under the action of the magnetic field, avoiding delamination caused by the large difference in performance between the surface layer and the underlying concrete; Examples 1 to 4 are all hydrothermal cured for 24 hours at a temperature of 60°C, and then naturally cured for 28 days. The high temperature environment can promote the contact hardening reaction between iron powder and silicate to form high-hardness metal silicate to improve impact resistance and wear resistance, and its impact resistance and wear resistance are significantly better than that of Control Example 4.

[0050] Table 2 Impact and wear resistance properties of different components As can be seen from Table 2, different components produce different impact and wear resistance effects. The impact and wear resistant surface layer material components of Example 1 are the most preferred mix ratio. The most preferred mix ratio is: 50 parts iron powder, 400 parts cement, 130 parts water, 660 parts fine aggregate, 920 parts coarse aggregate, and 13.5 parts activator. The reactive mixture is mixed and smoothed with the neodymium magnets, then hydrothermally cured at 60°C for 24 hours and then naturally cured for 28 days.

Claims

1. An iron-silicate anti-wear surface layer, characterized in that: The anti-wear surface layer is a uniform mixture of iron powder, cement, water, fine aggregate, coarse aggregate, and activator. It is evenly covered on the surface of hydraulic concrete, smoothed with a neodymium magnet wrapped in geotextile, and hydrothermally cured for 12 hours to 24 hours. The components in the mixture are mixed in the following mass proportions: 15 to 60 parts of iron powder, 300 to 500 parts of cement, 130 to 150 parts of water, 600 to 800 parts of fine aggregate, 800 to 1200 parts of coarse aggregate, and 10 to 15 parts of activator.

2. The iron-silicate anti-wear surface layer according to claim 1, characterized in that: The iron powder is an aggregate of iron particles with a size of 30 to 100 meshes.

3. The iron-silicate anti-wear surface layer according to claim 1, characterized in that: The activator is a high alkaline silicate solution.

4. The iron-silicate anti-wear surface layer according to claim 1, characterized in that: The components in the mixture are mixed in the following mass proportions: 30~50 parts of iron powder, 350~400 parts of cement, 130~135 parts of water, 650~700 parts of fine aggregate, 1000~1200 parts of coarse aggregate, and 13~15 parts of activator.

5. The iron-silicate anti-wear surface layer according to claim 3, characterized in that: The activator is a high alkaline silicate solution with a pH>13.

6. The iron-silicate anti-wear surface layer according to claim 1, characterized in that: The fine aggregate is one of natural sand and quartz sand, with a particle size of 0.075-4.75 mm; the coarse aggregate is basalt crushed stone, with a particle size of 5-40 mm.

7. The method for preparing the iron-silicate anti-wear surface layer according to any one of claims 1 to 6, characterized in that: The mixture is stirred evenly and poured on the concrete surface. It is then smoothed with a neodymium magnet wrapped in geotextile. Under the action of the magnetic field, a continuous transition structure with a decreasing iron powder content gradient from the surface to the inside is formed. Hydrothermal curing at 45℃~60℃ for 12h~24h allows the silicate in the cement to undergo a hydration reaction and the iron powder to undergo a contact hardening reaction under the action of the activator, together forming an iron-silicate anti-impact and wear surface layer.

8. The method for preparing the iron-silicate anti-wear surface layer according to claim 7, characterized in that: The thickness of the mixture on the concrete surface is 20mm~50mm.

9. The method for preparing the iron-silicate anti-wear surface layer according to claim 7, characterized in that: The curing temperature is 45℃~60℃ and the time is 12h~24h.

10. The method for preparing the iron-silicate anti-wear surface layer according to claim 9, characterized in that: The curing temperature is 60℃ and the time is 24h.

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