A kind of fast-hardening anti-seepage fine stone concrete around municipal road manhole cover

Abstract

The present invention provides a fast-hardening anti-seepage fine stone concrete around a municipal road manhole cover, comprising the following raw materials: sulphoaluminate cement, silicate cement, quartz sand, calcium chloride, lithium carbonate, hydroxypropyl methylcellulose, polycarboxylate water reducer, melon stone, sand, and water. Compared with the prior art, the present invention has the following beneficial effects: high strength can be achieved in a short time, construction efficiency can be significantly improved, and road closure time can be reduced; at the same time, enhanced anti-seepage and durability extend the service life and reduce municipal maintenance costs. The addition of fiber reinforcement plays a role in reinforcement and crack resistance. In the concrete, the fiber reinforcement is distributed in a random or directional manner. When the concrete hardens, these fibers will exist in the concrete matrix in a multi-directional staggered form to form a continuous three-dimensional network. This distribution characteristic allows the fibers to form a "bridging" effect inside the concrete, increasing the overall structural strength of the concrete.

Description

Technical Field

[0001] The invention belongs to the field of concrete, and in particular relates to a quick-hardening anti-seepage fine stone concrete around a municipal road manhole cover. Background Art

[0002] Urban pipeline inspection wells are an important part of urban infrastructure. Due to insufficient strength of the pavement material or improper construction around the wells, cracks, potholes and other damage often occur on the pavement around the wells, seriously affecting the flatness of the road and driving safety. The main reasons for this phenomenon include:

[0003] Material problems: The material quality of the road surface around the well is unqualified or the strength is insufficient, resulting in problems such as cracks and collapse in the road surface.

[0004] Construction problems: Improper construction, such as uneven thickness of the road surface around the well, resulting in uneven road surface, or a loose connection between the road surface and the well wall, resulting in road surface sinking and other problems.

[0005] Vehicle pressure: As vehicles travel around the inspection well for a long time, the road surface around the well is under great pressure, especially heavy-loaded vehicles cause more serious damage to the road surface around the well.

[0006] The conventional approach to repairing damaged pavement around inspection wells is to first break up the damaged pavement and then restore it with mortar, and then replace and install the manhole cover. Due to the low strength and poor durability of the mortar, the area where the manhole cover is replaced becomes a weak point in the pavement area, resulting in repeated and regular repairs, wasting manpower and increasing investment. The use of fast-hardening anti-seepage concrete instead of mortar can ensure that the strength of the repair area is not lower than the strength of the pavement, and can quickly restore road traffic. Because the amount of concrete around the manhole cover is usually not large, it is impossible to entrust a mixing station to produce concrete. Most of the existing repair materials are ordinary cement concrete, which takes a long time to cure and has average impermeability, and is easily damaged again in a short period of time. Therefore, the development of a fine stone concrete that can harden quickly and has excellent impermeability has become the key to solving the above problems. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a quick-hardening and anti-seepage fine stone concrete around the municipal road manhole cover to solve the problems raised in the above-mentioned background technology.

[0008] The present invention is achieved through the following technical scheme: a kind of quick-hardening anti-seepage fine stone concrete around the municipal road manhole cover, comprising the following raw materials: sulphoaluminate cement, silicate cement, quartz sand, calcium chloride, lithium carbonate, hydroxypropyl methylcellulose, polycarboxylate water reducer, fiber reinforcement, melon stone, sand and water.

[0009] As a preferred embodiment, the guami stone is a crushed stone with a particle size between 16-31.5 mm.

[0010] As a preferred embodiment, the following raw materials are also included: nano silicon powder, magnesium sulfate, carbon nanotubes;

[0011] in:

[0012] The silicon material with a purity of more than 99.99% is crushed into micron-sized particles, and then the silicon particles are placed in a supercritical carbon dioxide reactor, and the temperature and pressure of the carbon dioxide are controlled to be above 31.1°C and above 7.38MPa. Under supercritical conditions, the solubility of carbon dioxide can dissolve the oxide layer on the surface of the silicon particles. This process lasts for 2 hours, so that the carbon dioxide fully penetrates and evenly dissolves the oxide layer on the surface of the silicon. Hydrogen is introduced into the reactor, and a reduction reaction is carried out at a temperature of 400°C to 600°C to form nano-scale silicon powder. The silicon powder is recovered from the reactor through rapid cooling and gas injection, and ultrasonic dispersion treatment is carried out to obtain nano-silicon powder in the raw material. The nano-silicon powder prepared by the supercritical carbon dioxide method has extremely high purity and fine particle size. There is no oxide layer on its surface, and it can be more evenly dispersed in the cement matrix to form a denser microstructure. The high surface area of ​​the nano-silicon powder promotes the reaction with cement hydration products to generate more calcium silicate hydrate (CSH), thereby significantly improving the compressive strength and impermeability of concrete. In addition, nano-silicon powder can fill the tiny pores in concrete, reduce the porosity of concrete, and improve its durability and frost resistance;

[0013] Select magnesium oxide with a purity of more than 99% and dilute sulfuric acid as raw materials, dissolve magnesium oxide in dilute sulfuric acid to form a magnesium sulfate solution, place the solution in an electrolytic cell, and control the current density and voltage in the electrolytic cell to make the magnesium sulfate solution undergo an electrolytic reaction to generate a high-purity magnesium sulfate precipitate. The electrolysis time is more than 3 hours. After the reaction is completed, the magnesium sulfate powder in the raw material is obtained by filtering and drying, and adding silica gel during the drying process to prevent it from absorbing moisture and agglomerating in the air. In concrete, magnesium sulfate can react with calcium ions in cement to generate insoluble calcium sulfate and magnesium-calcium compounds. These products can form a hard and dense structure in concrete, improving the compressive strength and chemical corrosion resistance of concrete. Especially in salty environments, magnesium sulfate can effectively inhibit the diffusion of chloride ions in concrete and reduce the risk of corrosion of steel bars. In addition, the addition of magnesium sulfate can also regulate the early strength growth of concrete and shorten the curing time;

[0014] A layer of nano-nickel catalyst is coated on the surface of the graphite electrode, and the catalyst particles are evenly distributed on the electrode surface through high-temperature annealing treatment at 800°C to 900°C. The electrode is placed in a PECVD reactor, and high-purity methane is introduced as a carbon source gas, and hydrogen is introduced as a reducing gas at the same time. Under the action of a radio frequency power supply, a high-density plasma is formed to decompose methane and deposit carbon atoms on the surface of nano-nickel particles. This process is carried out at a temperature of 600°C to 700°C and lasts for 1 hour. After the growth is completed, the unreacted carbon source and catalyst residues are removed by cooling and ultrasonic cleaning, and finally the carbon nanotubes in the raw material are obtained. The carbon nanotubes form a three-dimensional network structure in the concrete, which greatly improves the mechanical properties of the concrete. Specifically, carbon nanotubes can bridge microcracks in concrete and prevent crack expansion, thereby significantly improving the tensile strength and flexural strength of concrete. Because carbon nanotubes have good electrical conductivity, they can also enhance the self-sensing ability of concrete, making concrete have a wide range of application potential in intelligent monitoring and structural health monitoring. In addition, carbon nanotubes can improve the impact and fatigue resistance of concrete, extending the service life of the structure.

[0015] As a preferred embodiment, the invention is composed of the following raw materials in proportion by weight:

[0016] Sulphoaluminate cement: 8000g;

[0017] Portland cement: 1000g;

[0018] Quartz sand: 1500g;

[0019] Calcium chloride: 100g;

[0020] Lithium carbonate: 40g;

[0021] Hydroxypropyl methylcellulose: 60g;

[0022] Polycarboxylate water reducer: 50g;

[0023] Guami stone: 6000g;

[0024] Sand: 4340g;

[0025] Water: 4500g;

[0026] Nano silicon powder: 100g;

[0027] Fiber reinforcement: 150g;

[0028] Magnesium sulfate: 30g;

[0029] Carbon nanotubes: 20g.

[0030] As a preferred embodiment, the fiber reinforcement is an additive for improving the performance of concrete, and is made of polypropylene resin, antioxidant, UV stabilizer, toughening agent and masterbatch;

[0031] The fiber reinforcement is prepared by the following steps: Ingredient ratio:

[0032] Polypropylene resin: 100 parts by weight

[0033] Antioxidant: 0.5 parts by weight

[0034] UV stabilizer: 0.2 parts by weight

[0035] Toughener: 1.0 parts by weight

[0036] Masterbatch: 0.5 parts by weight

[0037] Add all ingredients into a mixer and mix them evenly at a temperature of 80°C to 100°C for 30 to 60 minutes to ensure that all additives are evenly distributed in the polypropylene resin;

[0038] The uniformly mixed raw materials are fed into a melt extruder, melted at a high temperature of 180°C to 220°C, the extrusion process lasts for 1 to 2 hours, and the melted materials are extruded into a fiber shape through a spinneret; the extruded fibers are stretched on a stretching machine with a stretching ratio of 5 times; the stretched fibers are cooled in a cooling tank, the temperature of the cooling water is controlled at 10°C to 20°C, and the stretching process lasts for 10 to 20 minutes;

[0039] The cooled fibers are cut into specified lengths by a cutting machine; the cut fibers are surface treated, i.e., treated by plasma or coated with a binder.

[0040] A quick-hardening anti-seepage fine stone concrete around a municipal road manhole cover is prepared by the following steps:

[0041] Raw material preparation: prepare raw materials according to the formula requirements;

[0042] Pretreatment of raw materials: further grinding of nano-silicon powder, fiber reinforcement, carbon nanotubes, and cutting of fiber reinforcement;

[0043] Dry material mixing: adding sulphoaluminate cement, silicate cement, quartz sand, nano silicon powder, fiber reinforcement, carbon nanotubes, calcium chloride, lithium carbonate, hydroxypropyl methylcellulose and magnesium sulfate into a mixer in proportion for dry mixing;

[0044] Liquid additive mixing: dissolve the polycarboxylate water reducer in part of the water and add it to the mixer and mix with the dry material;

[0045] Add water and mix: Gradually add the remaining water during the mixing process and continue to stir to ensure uniform mixing;

[0046] Aggregate addition: gradually add the guami stone and sand into the mixer and mix them thoroughly with the concrete paste;

[0047] Blend: Blend all ingredients in a blender at medium speed until smooth.

[0048] After adopting the above technical solution, the beneficial effects of the present invention are: high strength can be achieved in a short time, construction efficiency can be significantly improved, and road closure time can be reduced; at the same time, enhanced impermeability and durability can prolong service life and reduce municipal maintenance costs. The addition of fiber reinforcement plays a role in strengthening and crack resistance. In concrete, the fiber reinforcement is distributed in a random or directional manner. When the concrete hardens, these fibers will exist in the concrete matrix in a multi-directional staggered form, forming a continuous three-dimensional network. This distribution characteristic allows the fibers to form a "bridging" effect inside the concrete, increasing the overall structural strength of the concrete. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The invention provides a technical solution: a quick-hardening anti-seepage fine stone concrete around a municipal road manhole cover, comprising the following raw materials: sulphoaluminate cement, silicate cement, quartz sand, calcium chloride, lithium carbonate, hydroxypropyl methylcellulose, polycarboxylate water reducer, fiber reinforcement, melon stone, sand and water.

[0051] Guami stone is a kind of crushed stone with a particle size between 16-31.5mm.

[0052] The following raw materials are also included: nano silicon powder, magnesium sulfate, carbon nanotubes;

[0053] in:

[0054] The silicon material with a purity of more than 99.99% is crushed into micron-sized particles, and then the silicon particles are placed in a supercritical carbon dioxide reactor, and the temperature and pressure of the carbon dioxide are controlled to be above 31.1°C and above 7.38MPa. Under supercritical conditions, the solubility of carbon dioxide can dissolve the oxide layer on the surface of the silicon particles. This process lasts for 2 hours, so that the carbon dioxide fully penetrates and evenly dissolves the oxide layer on the surface of the silicon. Hydrogen is introduced into the reactor, and a reduction reaction is carried out at a temperature of 400°C to 600°C to form nano-scale silicon powder. The silicon powder is recovered from the reactor through rapid cooling and gas injection, and ultrasonic dispersion treatment is carried out to obtain nano-silicon powder in the raw material. The nano-silicon powder prepared by the supercritical carbon dioxide method has extremely high purity and fine particle size. There is no oxide layer on its surface, and it can be more evenly dispersed in the cement matrix to form a denser microstructure. The high surface area of ​​the nano-silicon powder promotes the reaction with cement hydration products to generate more calcium silicate hydrate (CSH), thereby significantly improving the compressive strength and impermeability of concrete. In addition, nano-silicon powder can fill the tiny pores in concrete, reduce the porosity of concrete, and improve its durability and frost resistance;

[0055] Select magnesium oxide with a purity of more than 99% and dilute sulfuric acid as raw materials, dissolve magnesium oxide in dilute sulfuric acid to form a magnesium sulfate solution, place the solution in an electrolytic cell, and control the current density and voltage in the electrolytic cell to make the magnesium sulfate solution undergo an electrolytic reaction to generate a high-purity magnesium sulfate precipitate. The electrolysis time is more than 3 hours. After the reaction is completed, the magnesium sulfate powder in the raw material is obtained by filtering and drying, and adding silica gel during the drying process to prevent it from absorbing moisture and agglomerating in the air. In concrete, magnesium sulfate can react with calcium ions in cement to generate insoluble calcium sulfate and magnesium-calcium compounds. These products can form a hard and dense structure in concrete, improving the compressive strength and chemical corrosion resistance of concrete. Especially in salty environments, magnesium sulfate can effectively inhibit the diffusion of chloride ions in concrete and reduce the risk of corrosion of steel bars. In addition, the addition of magnesium sulfate can also regulate the early strength growth of concrete and shorten the curing time;

[0056] A layer of nano-nickel catalyst is coated on the surface of the graphite electrode, and the catalyst particles are evenly distributed on the electrode surface through high-temperature annealing treatment at 800°C to 900°C. The electrode is placed in a PECVD reactor, and high-purity methane is introduced as a carbon source gas, and hydrogen is introduced as a reducing gas at the same time. Under the action of a radio frequency power supply, a high-density plasma is formed to decompose methane and deposit carbon atoms on the surface of nano-nickel particles. This process is carried out at a temperature of 600°C to 700°C and lasts for 1 hour. After the growth is completed, the unreacted carbon source and catalyst residues are removed by cooling and ultrasonic cleaning, and finally the carbon nanotubes in the raw material are obtained. The carbon nanotubes form a three-dimensional network structure in the concrete, which greatly improves the mechanical properties of the concrete. Specifically, carbon nanotubes can bridge microcracks in concrete and prevent crack expansion, thereby significantly improving the tensile strength and flexural strength of concrete. Because carbon nanotubes have good electrical conductivity, they can also enhance the self-sensing ability of concrete, making concrete have a wide range of application potential in intelligent monitoring and structural health monitoring. In addition, carbon nanotubes can improve the impact and fatigue resistance of concrete, extending the service life of the structure.

[0057] The fiber reinforcement is an additive for improving the performance of concrete, and is made of polypropylene resin, antioxidant, UV stabilizer, toughening agent and masterbatch;

[0058] The fiber reinforcement is prepared by the following steps: Ingredient ratio:

[0059] Polypropylene resin: 100 parts by weight

[0060] Antioxidant: 0.5 parts by weight

[0061] UV stabilizer: 0.2 parts by weight

[0062] Toughener: 1.0 parts by weight

[0063] Masterbatch: 0.5 parts by weight

[0064] Add all ingredients into a mixer and mix them evenly at a temperature of 80°C to 100°C for 30 to 60 minutes to ensure that all additives are evenly distributed in the polypropylene resin;

[0065] The uniformly mixed raw materials are fed into a melt extruder, melted at a high temperature of 180°C to 220°C, the extrusion process lasts for 1 to 2 hours, and the melted materials are extruded into a fiber shape through a spinneret; the extruded fibers are stretched on a stretching machine with a stretching ratio of 5 times; the stretched fibers are cooled in a cooling tank, the temperature of the cooling water is controlled at 10°C to 20°C, and the stretching process lasts for 10 to 20 minutes;

[0066] The cooled fibers are cut into specified lengths by a cutting machine; the cut fibers are surface treated, i.e., treated by plasma or coated with a binder.

[0067] A quick-hardening anti-seepage fine stone concrete around a municipal road manhole cover is prepared by the following steps:

[0068] Raw material preparation: prepare raw materials according to the formula requirements;

[0069] Pretreatment of raw materials: further grinding of nano-silicon powder, fiber reinforcement, carbon nanotubes, and cutting of fiber reinforcement;

[0070] Dry material mixing: adding sulphoaluminate cement, silicate cement, quartz sand, nano silicon powder, fiber reinforcement, carbon nanotubes, calcium chloride, lithium carbonate, hydroxypropyl methylcellulose and magnesium sulfate into a mixer in proportion for dry mixing;

[0071] Liquid additive mixing: dissolve the polycarboxylate water reducer in part of the water and add it to the mixer and mix with the dry material;

[0072] Add water and mix: Gradually add the remaining water during the mixing process and continue to stir to ensure uniform mixing;

[0073] Aggregate addition: gradually add the guami stone and sand into the mixer and mix them thoroughly with the concrete paste;

[0074] Blend: Blend all ingredients in a blender at medium speed until smooth.

[0075] Example 1 is composed of the following raw materials in proportion by weight:

[0076] Sulphoaluminate cement: 8000g;

[0077] Portland cement: 1000g;

[0078] Quartz sand: 1500g;

[0079] Calcium chloride: 100g;

[0080] Lithium carbonate: 40g;

[0081] Hydroxypropyl methylcellulose: 60g;

[0082] Polycarboxylate water reducer: 50g;

[0083] Guami stone: 6000g;

[0084] Sand: 4340g;

[0085] Water: 4500g;

[0086] Nano silicon powder: 100g;

[0087] Fiber reinforcement: 150g;

[0088] Magnesium sulfate: 30g;

[0089] Carbon nanotubes: 20g.

[0090] In the above materials, specifically:

[0091] In the present invention, sulphoaluminate cement provides rapid hardening characteristics of concrete, so that the concrete can reach sufficient strength in a short time, reduce the waiting time after construction, and improve construction efficiency.

[0092] In the formula, silicate cement supplements the deficiency of sulphoaluminate cement, increases the later strength of concrete and ensures that the concrete maintains stable performance over a long period of time.

[0093] In concrete, quartz sand acts as fine aggregate, increasing the density and strength of concrete while improving its wear resistance and impermeability.

[0094] By adding calcium chloride, the initial setting time of concrete is greatly shortened, which speeds up the construction progress and enables the concrete to harden quickly even in cold environments.

[0095] In the present invention, lithium carbonate improves the early strength of concrete and enhances its crack resistance, effectively avoiding cracks caused by early hydration heat release.

[0096] In the present invention, hydroxypropyl methylcellulose improves the operability and construction performance of concrete and prevents water seepage and segregation of concrete.

[0097] In the present invention, the polycarboxylate water reducer reduces the amount of water used, improves the density and strength of concrete, and enhances its anti-seepage performance.

[0098] As a coarse aggregate, guami stone provides a skeleton in concrete, improving the compressive strength and durability of concrete.

[0099] In concrete, sand fills the gaps between aggregates, increases the density of concrete, and ensures its mechanical properties and anti-permeability properties.

[0100] In the present invention, nano silicon powder greatly improves the compressive strength and impermeability of concrete, fills the tiny pores in the concrete, forms a more compact structure, and improves durability.

[0101] Fiber reinforcement forms a three-dimensional network structure in concrete, which greatly improves the toughness of concrete and prevents cracking. It is especially suitable for the periphery of municipal road manhole covers that are subject to high-intensity impact.

[0102] The addition of magnesium sulfate accelerates the early strength development of concrete, ensuring that the concrete reaches the strength required for construction in a shorter period of time.

[0103] In the present invention, carbon nanotubes further improve the compressive strength and toughness of concrete, and due to their electrical conductivity, they may provide potential integration capabilities for future intelligent manhole cover monitoring systems.

[0104] In Example 1, in order to compare the performance of the quick-hardening impermeable fine stone concrete around the municipal road manhole cover of the present invention with the commercially available C30 concrete, we will make test blocks according to the standard method and conduct compressive strength, flexural strength and tensile strength tests after 1 day, 3 days and 28 days respectively. The following is a detailed description of the test method and results.

[0105] 1. Preparation of test blocks

[0106] Test block specifications:

[0107] A 150 mm × 150 mm × 150 mm cubic mold was used to make the compressive strength test block.

[0108] A 100 mm × 100 mm × 400 mm prism mold was used to make the flexural strength test block.

[0109] A cubic mold of 150 mm × 150 mm × 150 mm was used to make the splitting tensile strength test block.

[0110] Concrete preparation:

[0111] Concrete was prepared according to the formula of the present invention and the standard mix ratio of commercially available C30 concrete.

[0112] Pour the mixed concrete into the mold, filling it to 1 / 3 of the height each time, and use a vibrator to compact it.

[0113] After pouring, smooth the surface with a trowel.

[0114] Maintenance:

[0115] The test block was left in the mold for 24 hours and then demoulded and placed in a standard curing room for curing (temperature of 20±2°C and humidity of more than 95%).

[0116] The test pieces were taken out at different ages (1 day, 3 days, 28 days) and the corresponding tests were carried out.

[0117] 2. Detection Method

[0118] 1. Compressive strength test

[0119] Standard: In accordance with GB / T 50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0120] method:

[0121] A standard-sized cubic test block is placed between two steel plates in the press.

[0122] Apply pressure gradually and record the maximum pressure value when the test block fails.

[0123] The compressive strength is calculated according to the following formula:

[0124] F C =P / A

[0125] in,

[0126] F C is the compressive strength (MPa),

[0127] P is the failure load (N),

[0128] A is the pressure area (mm2).

[0129] 2. Flexural strength test

[0130] Standard: In accordance with GB / T 50081-2019.

[0131] method:

[0132] Place the prism specimen on the flexural testing machine and test it in a three-point loading mode. Apply the load gradually and record the maximum load when the specimen is destroyed.

[0133] The flexural strength is calculated according to the following formula:

[0134] F r =PL / bd 2

[0135] F r is the flexural strength (MPa),

[0136] P is the failure load (N),

[0137] L is the support distance (mm),

[0138] b is the width of the test block (mm),

[0139] d is the test block height (mm).

[0140] 3. Splitting tensile strength test

[0141] Standard: In accordance with GB / T 50081-2019.

[0142] method:

[0143] The cubic test block is placed horizontally between the upper and lower steel plates of the press.

[0144] Apply pressure gradually and record the maximum pressure value when the test block fails.

[0145] The splitting tensile strength is calculated according to the following formula:

[0146] F t =2P / πLD

[0147] in,

[0148] F t is the splitting tensile strength (MPa),

[0149] P is the failure load (N),

[0150] L is the length of the test piece (mm),

[0151] D is the test block height (mm).

[0152] 3. Test results

[0153] 1. Compressive strength (MPa) as shown in Table 1

[0154] Table 1

[0155]

[0156] 2. Flexural strength (MPa) as shown in Table 2

[0157] Table 2

[0158]

[0159] 3. Splitting tensile strength (MPa) as shown in Table 3

[0160] Table 3

[0161]

[0162]

[0163] 4. Analysis of test results

[0164] Compressive strength:

[0165] The compressive strength of the concrete of the present invention at 1 day and 3 days is significantly higher than that of the commercial C30 concrete, showing a faster early strength development. At 28 days, the compressive strength of the concrete of the present invention is still higher than that of the C30 concrete, indicating that it has a higher ultimate strength.

[0166] Flexural strength:

[0167] The test results of flexural strength show that the flexural strength of the concrete of the present invention is significantly better than that of the commercially available C30 concrete at all ages, especially at the ages of 1 day and 3 days, showing better toughness and crack resistance.

[0168] Splitting tensile strength:

[0169] In the splitting tensile strength test, the concrete of the present invention performs better than the commercially available C30 concrete at all ages, indicating that it has stronger tensile properties and is suitable for structural parts that need to withstand tensile stress, such as the periphery of manhole covers.

[0170] Example 2: In order to comprehensively evaluate the performance of fast-hardening impermeable fine-stone concrete with different formulations, we designed three concrete formulations with different weight fractions. Each formulation was compared with commercially available C30 concrete, and the compressive strength, flexural strength and tensile strength were tested at 1 day, 3 days and 28 days.

[0171] Concrete recipe

[0172] Formula A: High Fiber Enhanced Formula

[0173] Sulphoaluminate cement: 8000g

[0174] Portland cement: 1000g

[0175] Quartz sand: 1500g

[0176] Calcium chloride: 100g

[0177] Lithium carbonate: 40g

[0178] Hydroxypropyl methylcellulose: 60g

[0179] Polycarboxylate water reducer: 50g

[0180] Guami Stone: 6000g

[0181] Sand: 4340g

[0182] Water: 4500g

[0183] Nano silicon powder: 100g

[0184] Fiber reinforcement: 200g

[0185] Magnesium sulfate: 30g

[0186] Carbon nanotubes: 20g

[0187] Formulation B: Medium fiber reinforced formulation Sulphoaluminate cement: 8000g

[0188] Portland cement: 1000g

[0189] Quartz sand: 1500g

[0190] Calcium chloride: 100g

[0191] Lithium carbonate: 40g

[0192] Hydroxypropyl methylcellulose: 60g

[0193] Polycarboxylate water reducer: 50g

[0194] Guami Stone: 6000g

[0195] Sand: 4340g

[0196] Water: 4500g

[0197] Nano silicon powder: 100g

[0198] Fiber reinforcement: 150g

[0199] Magnesium sulfate: 30g

[0200] Carbon nanotubes: 20g

[0201] Recipe C: Low Fiber Enhanced Recipe

[0202] Sulphoaluminate cement: 8000g

[0203] Portland cement: 1000g

[0204] Quartz sand: 1500g

[0205] Calcium chloride: 100g

[0206] Lithium carbonate: 40g

[0207] Hydroxypropyl methylcellulose: 60g

[0208] Polycarboxylate water reducer: 50g

[0209] Guami Stone: 6000g

[0210] Sand: 4340g

[0211] Water: 4500g

[0212] Nano silicon powder: 100g

[0213] Fiber reinforcement: 100g

[0214] Magnesium sulfate: 30g

[0215] Carbon nanotubes: 20g

[0216] Control group: Commercially available C30 concrete

[0217] A commercially available standard C30 concrete was used for comparison.

[0218] In the above formula, only the amount of fiber reinforcement was changed, and the others remained unchanged.

[0219] Test methods

[0220] Test block preparation

[0221] Each formula of concrete and commercially available C30 concrete were cast into standard test blocks of 100mm×100mm×100mm.

[0222] The specimens were cured at room temperature (20±2℃) and tested at the ages of 1 day, 3 days and 28 days.

[0223] Compressive strength test

[0224] The compressive strength test was carried out using a pressure testing machine with a loading rate of 0.5 MPa / s.

[0225] Three experiments were conducted at each age and the average value was taken.

[0226] Flexural strength test

[0227] The flexural strength test was carried out using a three-point bending test device with a span of 100 mm and a loading rate of 0.05 MPa / s.

[0228] Three experiments were conducted at each age and the average value was taken.

[0229] Tensile strength test

[0230] The splitting tensile strength test method was adopted, and the loading rate was 0.1MPa / s.

[0231] Three experiments were conducted at each age and the average value was taken.

[0232] Test results

[0233] 1. Compressive strength test results (unit: MPa), as shown in Table 4

[0234] Table 4

[0235] Age Recipe A Recipe B Recipe C Commercially available C30 1 day 27.3 25.5 23.8 18.2 3 days 41.2 39.8 36.5 28.6 28 days 54.7 52.4 49.3 41.0

[0236] 2. Flexural strength test results (unit: MPa), as shown in Table 5

[0237] Table 5

[0238] Age Recipe A Recipe B Recipe C Commercially available C30 1 day 4.2 3.8 3.5 2.9 3 days 6.8 6.2 5.7 4.5 28 days 8.1 7.5 6.9 5.8

[0239] 3. Tensile strength test results (unit: MPa), as shown in Table 6

[0240] Table 6

[0241] Age Recipe A Recipe B Recipe C Commercially available C30 1 day 3.1 2.7 2.4 1.9 3 days 4.9 4.5 4.1 3.3 28 days 6.4 5.8 5.2 4.0

[0242] Results Analysis

[0243] Compressive strength: The compressive strength of concrete with the three formulations is better than that of commercially available C30 concrete, with formulation A performing best and showing significant improvement at all ages.

[0244] Flexural strength: Compared with the commercially available C30 concrete, the flexural strength of the three formulations is improved, especially within 28 days, the flexural strength of formulation A is increased by about 40%.

[0245] Tensile strength: Formula A has the highest tensile strength at all ages, and its tensile strength at 28 days old reaches 6.4MPa, which is significantly better than the 4.0MPa of commercially available C30 concrete.

[0246] Through experiments with different formulas, it can be concluded that the content of fiber reinforcement has a significant effect on the mechanical properties of concrete. Formula A with a high fiber reinforcement content performs best in terms of compressive, flexural and tensile strength, but considering the price factor, formula B is more suitable for municipal projects that require high strength and durability.

[0247] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A quick-hardening anti-seepage fine stone concrete around a municipal road manhole cover, characterized in that: The raw materials include: sulphoaluminate cement, silicate cement, quartz sand, calcium chloride, lithium carbonate, hydroxypropyl methylcellulose, polycarboxylate water reducer, fiber reinforcement, guami stone, sand, water; The following raw materials are also included: nano silicon powder, magnesium sulfate, carbon nanotubes; in: The silicon material with a purity of more than 99.99% is crushed into micron-sized particles, and then the silicon particles are placed in a supercritical carbon dioxide reactor, and the temperature and pressure of the carbon dioxide are controlled to be above 31.1°C and above 7.38 MPa. Under supercritical conditions, the solubility of the carbon dioxide can dissolve the oxide layer on the surface of the silicon particles. This process lasts for 2 hours, so that the carbon dioxide can fully penetrate and evenly dissolve the oxide layer on the surface of the silicon. Hydrogen is introduced into the reactor, and a reduction reaction is carried out at a temperature of 400°C to 600°C to form nano-sized silicon powder. The silicon powder is recovered from the reactor by rapid cooling and gas injection, and ultrasonic dispersion treatment is carried out to obtain nano-sized silicon powder in the raw material. Selecting magnesium oxide with a purity of more than 99% and dilute sulfuric acid as raw materials, dissolving magnesium oxide in dilute sulfuric acid to form a magnesium sulfate solution, placing the solution in an electrolytic cell, and controlling the current density and voltage in the electrolytic cell to cause an electrolytic reaction in the magnesium sulfate solution to generate a high-purity magnesium sulfate precipitate, the electrolysis time being more than 3 hours, and after the reaction is completed, filtering and drying, and adding silica gel during the drying process to prevent it from absorbing moisture and agglomerating in the air, to obtain magnesium sulfate powder in the raw material; A layer of nano nickel catalyst is coated on the surface of the graphite electrode, and a high temperature annealing treatment is performed at 800°C to 900°C to make the catalyst particles evenly distributed on the electrode surface. The electrode is placed in a PECVD reactor, and high-purity methane is introduced as a carbon source gas, and hydrogen is introduced as a reducing gas at the same time. Under the action of a radio frequency power supply, a high-density plasma is formed to decompose the methane and deposit carbon atoms on the surface of the nano nickel particles. This process is carried out at a temperature of 600°C to 700°C and lasts for 1 hour. After the growth is completed, the unreacted carbon source and catalyst residues are removed by cooling and ultrasonic cleaning, and finally the carbon nanotubes in the raw material are obtained.

2. The quick-hardening anti-seepage fine stone concrete around the municipal road manhole cover as claimed in claim 1, characterized in that: The guami stone is a crushed stone with a particle size between 16 and 31.5 mm.

3. The quick-hardening anti-seepage fine stone concrete around the municipal road manhole cover as claimed in claim 2, characterized in that: It is composed of the following raw materials in proportion by weight: Sulphoaluminate cement: 8000g; Portland cement: 1000g; Quartz sand: 1500g; Calcium chloride: 100g; Lithium carbonate: 40g; Hydroxypropyl methylcellulose: 60g; Polycarboxylate water reducer: 50g; Guami stone: 6000g; Sand: 4340g; Water: 4500g; Nano silicon powder: 100g; Fiber reinforcement: 150g; Magnesium sulfate: 30g; Carbon nanotubes: 20g.

4. The quick-hardening anti-seepage fine stone concrete around the municipal road manhole cover as claimed in claim 3, characterized in that: The fiber reinforcement is an additive for improving the performance of concrete, and is made of polypropylene resin, antioxidant, ultraviolet stabilizer, toughening agent and masterbatch.

5. The quick-hardening anti-seepage fine stone concrete around the municipal road manhole cover as claimed in claim 4, characterized in that: The fiber reinforcement is prepared by the following steps: ingredient ratio: Polypropylene resin: 100 parts by weight Antioxidant: 0.5 parts by weight UV stabilizer: 0.2 parts by weight Toughener: 1.0 parts by weight Masterbatch: 0.5 parts by weight Add all ingredients into a mixer and mix them evenly at a temperature of 80°C to 100°C for 30 to 60 minutes to ensure that all additives are evenly distributed in the polypropylene resin; The uniformly mixed raw materials are fed into a melt extruder, melted at a high temperature of 180°C to 220°C, the extrusion process lasts for 1 to 2 hours, and the melted materials are extruded into a fiber shape through a spinneret; the extruded fibers are stretched on a stretching machine with a stretching ratio of 5 times; the stretched fibers are cooled in a cooling tank, the temperature of the cooling water is controlled at 10°C to 20°C, and the stretching process lasts for 10 to 20 minutes; The cooled fibers are cut into specified lengths by a cutting machine; the cut fibers are surface treated, i.e., treated by plasma or coated with a binder.

6. The quick-hardening anti-seepage fine stone concrete around the municipal road manhole cover as claimed in claim 5, characterized in that: Prepared by the following steps: Raw material preparation: prepare raw materials according to formula requirements; Pretreatment of raw materials: further grinding of nano-silicon powder, fiber reinforcement, carbon nanotubes, and cutting of fiber reinforcement; Dry material mixing: adding sulphoaluminate cement, silicate cement, quartz sand, nano silicon powder, fiber reinforcement, carbon nanotubes, calcium chloride, lithium carbonate, hydroxypropyl methylcellulose and magnesium sulfate into a mixer in proportion for dry mixing; Liquid additive mixing: dissolve the polycarboxylate water reducer in part of the water and add it to the mixer and mix with the dry material; Add water and mix: Gradually add the remaining water during the mixing process and continue to stir to ensure uniform mixing; Aggregate addition: gradually add the guami stone and sand into the mixer and mix them thoroughly with the concrete paste; Blend: Blend all ingredients in a blender at medium speed until smooth.

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