Concrete for waste fiber water net engineering

Abstract

The invention relates to the field of concrete, and particularly discloses waste fiber concrete for water net engineering, which is prepared from the following ingredients in parts by weight: 40 to 60 parts of cement, 130 to 200 parts of aggregate, 15 to 25 parts of mineral materials, 0.3 to 1 part of polyolefin reinforcing agents, 0.1 to 1.2 parts of dispersing agents and 3 to 10 parts of modified waste fibers, and the water-binder ratio is smaller than or equal to 0.4. The modified waste fibers are prepared by the following steps: cleaning waste fibers, dipping the cleaned waste fibers in a silane coupling agent solution, carrying out heating reaction, then adding a plasticizer, and carrying out plasma irradiation. By controlling the use amount of the cement, the aggregate, the mineral material and other raw material components and controlling the water-binder ratio, the compactness of the concrete material is high, and the waste fibers are modified and then utilized, so that the finally prepared concrete has higher compression resistance and tensile property, meanwhile, the waste treatment pressure is reduced, the carbon emission is reduced, and the environment-friendly and energy-saving effects are achieved. The environment friendliness is improved.

Description

Technical Field

[0001] This application relates to the field of concrete, and more specifically, it relates to a kind of concrete for waste fiber water network projects. Background Art

[0002] A water network project refers to a series of water conservancy facilities (such as reservoirs, channels, pumping stations, etc.) constructed to rationally distribute and regulate water resources within a region to ensure the water demand for various aspects such as agriculture, industry, and daily life. Water network projects are of great significance in promoting the efficient utilization of water resources, regulating water sources, solving water supply problems, and improving drought resistance. In water network projects, concrete, as an important building material, is widely used in the construction of water conservancy facilities.

[0003] With the acceleration of the urbanization process, various waste concretes will be generated in demolition, renovation and other projects. The recycled aggregates and waste fibers recovered from waste concrete are mainly used to prepare low-strength concrete, whose mechanical properties are poor. Especially in low-temperature environments, it is very easy to crack and cannot meet the requirements of water network projects for concrete. Summary of the Invention

[0004] To solve the above problems, this application provides a kind of concrete for waste fiber water network projects.

[0005] The concrete for waste fiber water network projects provided by this application adopts the following technical solutions: A kind of concrete for waste fiber water network projects, comprising the following components in parts by weight: 40 - 60 parts of cement, 130 - 200 parts of aggregate, 15 - 25 parts of mineral material, 0.3 - 1 part of polyolefin reinforcing agent, 0.1 - 1.2 parts of dispersant, 3 - 10 parts of modified waste fiber, and the water-binder ratio ≤ 0.4; The modified waste fiber is prepared through the following steps: washing the waste fiber and then impregnating it in a silane coupling agent solution, heating up for reaction, and then adding a plasticizer and performing plasma irradiation.

[0006] Further, the silane coupling agent model is KH550 or KH560. KH550 is further preferred.

[0007] Further, the power of plasma irradiation is 50 - 100W, and the irradiation time is 20 - 30min.

[0008] By adopting the above technical solutions, the dosages of each raw material component such as cement, aggregate, and mineral material are controlled, and the water-binder ratio is controlled, so that the density of the concrete material is high. After modifying and reusing the waste fiber, the finally prepared concrete has higher compressive and tensile properties, uses waste resources to replace part of the traditional aggregate or cement components, reduces the waste treatment pressure and carbon emissions, and improves environmental friendliness.

[0009] When modifying waste fibers, since the silane coupling agent contains ethoxy groups and amino groups, the ethoxy groups can be hydrolyzed to form silanols, which bond with the groups on the fiber surface. The amino groups have strong reactivity and can form coordination bonds with calcium ions in the cement hydration products, or form hydrogen bonds with the hydroxyl groups in the C-S-H gel. They can also promote the oriented growth of cement hydration products on the fiber surface, reduce pores, and enhance the mechanical interlocking force. The silane bridges the fiber and the cement matrix, and the covalent bonds and hydrogen bonds work together to improve the fiber-matrix stress transfer efficiency, delay crack propagation, and enhance the durability of concrete.

[0010] During plasma irradiation, high-energy particles bombard the fiber surface, breaking the chemical bonds on the fiber surface (such as C-H, C-C), generating active sites (free radicals), increasing the surface energy, and playing a role in activating the surface. Under the action of a plasticizer, functional groups are further grafted, significantly improving the interfacial properties between the waste fiber and the polymer matrix. At the same time, the active functional groups form hydrogen bonds or ionic bonds with Ca 2+ , Si-O - etc. Plasma irradiation can also form nano-scale rough structures (such as grooves, holes) on the fiber surface. The rough surface increases the contact area, increases the mechanical interlocking force, reduces interfacial slip, and improves the low-temperature tensile properties of concrete materials.

[0011] Preferably, the silane coupling agent solution is an ethanol solution containing a silane coupling agent, and the concentration of the ethanol solution is 0.5 - 2%.

[0012] Preferably, the conditions for the temperature-rising reaction are: raising the temperature to 50 - 60 °C and reacting for 1 - 2 hours.

[0013] By adopting the above technical solution, heating can accelerate the hydrolysis and condensation reaction rate of silane, ensure the full diffusion of silane molecules to the fiber surface, and ensure that the fiber surface is fully grafted with a silane layer. The temperature condition of 50 - 60 °C can also promote the volatilization of ethanol and avoid the influence of residual solvents on the fiber-matrix bonding.

[0014] Preferably, the aggregate includes basalt gravel with a continuous gradation of 5 - 20 mm in particle size and manufactured sand with a continuous gradation of 0.2 - 4 mm in particle size.

[0015] By adopting the above technical solution, the basalt gravel provides a skeleton support, reduces shrinkage, and enhances the compressive strength. The manufactured sand fills the gaps between the coarse aggregates and combines with the cement paste to form a dense structure. The compound use of basalt gravel and manufactured sand enables the concrete material to have better durability in water network projects.

[0016] Preferably, the plasticizer is one of dibutyl phthalate and dioctyl sebacate.

[0017] Preferably, the dispersant is one of polyethylene glycol and hydroxypropyl methylcellulose.

[0018] The long-chain alkyl groups contained in the plasticizer can further reduce the migration of the plasticizer from the fiber to the matrix through steric hindrance effect, improving the long-term stability of the material. The dispersant can effectively improve the dispersibility of each raw material component, reduce the agglomeration of modified waste fibers during the mixing process, and ensure that each raw material component can be evenly dispersed in the entire concrete system, thereby improving the comprehensive performance of the concrete material.

[0019] Preferably, the polyolefin reinforcing agent is one or both of polyethylene powder and polypropylene powder.

[0020] Furthermore, the polyolefin reinforcing agent is preferably a mixture of polyethylene powder and polypropylene powder, and the mass ratio of polyethylene powder to polypropylene powder is 1:(1 - 2).

[0021] By adopting the above technical solution, the polyolefin reinforcing agent has good flexibility. Selecting granular polyolefin reinforcing agent forms an energy dissipation network in the matrix, absorbs the internal stress of the concrete, inhibits the propagation of microcracks, the powder surface is smooth, which can reduce the friction between aggregates and improve the fluidity of the concrete. The polyolefin reinforcing agent can cooperate with the plasticizer, in which the ester groups in dibutyl phthalate and dioctyl sebacate form a physical adsorption layer on the polyolefin surface, promoting stress transfer and forming a toughening network. The polyolefin reinforcing agent can also cooperate with the dispersant, stabilizing the suspension of polymer powder through steric hindrance effect, preventing sedimentation or agglomeration during mixing, and the hydrophilic chain segments of hydroxypropyl methylcellulose wrap the polyolefin reinforcing agent, enhancing the wettability with the cement paste, jointly optimizing the microstructure of the material and significantly improving the comprehensive performance of the concrete.

[0022] Preferably, the mineral materials include at least one of fly ash, silica fume, and carbide slag.

[0023] Furthermore, the mineral materials are fly ash and carbide slag, and the mass ratio of fly ash to carbide slag is 1:0.2 - 0.5. Fly ash contains abundant silica and alumina substances, which can react with carbide slag to promote the autogenous hydration reaction of the system, further enhancing the strength of the gel system.

[0024] Preferably, the waste fibers include at least one of glass fiber, polyester fiber, polyethylene fiber, and polypropylene fiber.

[0025] Furthermore, the waste fibers are preferably a mixture of glass fiber and polypropylene fiber.

[0026] Furthermore, the length of the waste fibers is 10 - 50 mm, and the diameter ≤ 1 mm.

[0027] By adopting the above technical solution, the waste fibers can enhance the interfacial interaction between them and the substrate after modification, and improve the mechanical properties of the material.

[0028] In summary, the present application has the following beneficial effects: 1. In the present application, by controlling the dosages of raw material components such as cement, aggregate, and mineral materials, and controlling the water-binder ratio, the density of the concrete material is high, and the waste fibers are modified and reused, so that the finally prepared concrete has higher compressive and tensile properties. Using waste resources to replace some traditional aggregate or cement components reduces the waste treatment pressure and carbon emissions, and improves environmental friendliness.

[0029] 2. When modifying the waste fibers, since the silane coupling agent contains ethoxy groups and amino groups, the ethoxy groups can be hydrolyzed to form silanols, which bond with the groups on the fiber surface. The amino groups have strong reactivity and can form coordination bonds with calcium ions in the cement hydration products, or form hydrogen bonds with the hydroxyl groups in the C-S-H gel. They can also promote the directional growth of cement hydration products on the fiber surface, reduce pores, and enhance the mechanical bite force. The silane bridges the fiber and the cement matrix, and the covalent bond and hydrogen bond act synergistically to improve the fiber-matrix stress transfer efficiency, delay crack propagation, and improve the durability of the concrete. At the same time, when using plasma irradiation, high-energy particles bombard the fiber surface, breaking the chemical bonds on the fiber surface (such as C-H, C-C), generating active sites (free radicals), increasing the surface energy, and playing a role in activating the surface. The ester groups in the plasticizer release carboxylic acid groups under the conditions of plasma irradiation and the coexistence of moisture, and further graft functional groups carboxyl groups on the surface of the waste fibers, significantly improving the interfacial properties between the waste fibers and the polymer matrix. At the same time, the active functional groups amino and hydroxyl contained in the modified waste fibers can form hydrogen bonds or ionic bonds with Ca 2+ 、Si-O - etc. in the cement matrix. Plasma irradiation can also form a nanoscale rough structure (such as grooves, holes) on the fiber surface. The rough surface increases the contact area, increases the mechanical bite force, reduces interfacial slippage, and improves the low-temperature tensile properties of the concrete material. This modification process first treats the waste fibers with a silane coupling agent, which plays a catalytic and stabilizing role in the grafting on the surface of the waste fibers, and synergizes with plasma irradiation to jointly improve the grafting rate and grafting stability of the waste fiber surface.

[0030] 3. The polyolefin enhancer has good flexibility. Granular polyolefin enhancer is selected to form an energy dissipation network in the matrix, absorb the internal stress of concrete, inhibit the propagation of microcracks, and the smooth surface of the powder can reduce the friction between aggregates and improve the fluidity of concrete. The polyolefin enhancer can cooperate with plasticizers. The ester groups in dibutyl phthalate and dioctyl sebacate form a physical adsorption layer on the surface of the polyolefin, promoting stress transfer and forming a toughening network. The polyolefin enhancer can also cooperate with dispersants to stabilize the suspension of polymer powder through steric hindrance effect, preventing sedimentation or agglomeration during stirring. The hydrophilic chain segments of hydroxypropyl methylcellulose wrap the polyolefin enhancer, enhancing the wettability with cement paste, jointly optimizing the microstructure of the material, and significantly improving the comprehensive performance of concrete. Detailed implementation manners

[0031] The following will describe the implementation schemes of the present invention in detail in combination with embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. The specific conditions not specified in the embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not specified for the manufacturer can be obtained as conventional products through commercial purchase.

[0032] Preparation Example 1 The modified waste fibers are prepared through the following steps: 10 kg of waste fibers (glass fibers and polyester fibers) are removed of impurities and then ultrasonically cleaned, and then immersed in an ethanol solution containing silane coupling agent KH550, where the concentration of the ethanol solution is 0.5%. The temperature is raised to 50 °C and reacted for 1 hour. Then, 0.1 kg of plasticizer dibutyl phthalate is added and plasma irradiation is carried out under the condition of a power of 50 W for 30 min. Among them, 5 L of the ethanol solution containing silane coupling agent is used for every 5 kg of waste fibers, the mass ratio of glass fibers to polyester fibers is 1:1.5, the length of glass fibers and polyester fibers is 40 - 50 mm, and the diameter is ≤1 mm.

[0033] Preparation Example 2 The modified waste fibers are prepared through the following steps: 5 kg of waste fibers (polyethylene fibers) are removed of impurities and then ultrasonically cleaned, and then immersed in an ethanol solution containing silane coupling agent KH560, where the concentration of the ethanol solution is 2%. The temperature is raised to 60 °C and reacted for 0.5 hour. Then, 0.06 kg of plasticizer dioctyl sebacate is added and plasma irradiation is carried out under the condition of a power of 50 W for 50 min. Among them, 5 L of the ethanol solution containing silane coupling agent is used for every 5 kg of waste fibers, the length of polyethylene fibers is 50 - 60 mm, and the diameter is ≤1 mm.

[0034] Preparation Example 3 The modified waste fibers are prepared through the following steps: 15 kg of waste fibers (polyester fibers, polyethylene fibers, and polypropylene fibers) are cleaned ultrasonically after removing impurities, and then immersed in an ethanol solution containing silane coupling agent KH550, where the concentration of the ethanol solution is 2%. The temperature is raised to 60 °C and the reaction is carried out for 2 hours. Subsequently, 0.1 kg of plasticizer dioctyl sebacate is added and plasma irradiation is carried out under the condition of a power of 100 W for 20 min; for every 5 kg of waste fibers, 5 L of the ethanol solution containing the silane coupling agent is used. The mass ratio of polyester fibers, polyethylene fibers, and polypropylene fibers is 2:1:0.7, and the length of polyester fibers, polyethylene fibers, and polypropylene fibers is 10 - 20 mm, with a diameter ≤ 1 mm.

[0035] Preparation Example 4 The modified waste fibers are prepared through the following steps: 10 kg of waste fibers (glass fibers and polypropylene fibers) are cleaned ultrasonically after removing impurities, and then immersed in an ethanol solution containing silane coupling agent KH550, where the concentration of the ethanol solution is 1.2%. The temperature is raised to 60 °C and the reaction is carried out for 1 hour. Subsequently, 0.08 kg of plasticizer dibutyl phthalate is added and plasma irradiation is carried out under the condition of a power of 80 W for 20 min; for every 5 kg of waste fibers, 5 L of the ethanol solution containing the silane coupling agent is used. The mass ratio of glass fibers and polypropylene fibers is 1:1, and the length of glass fibers and polypropylene fibers is 20 - 30 mm, with a diameter ≤ 1 mm.

[0036] Example 1

[0037] A kind of concrete for water network project using waste fibers comprises the following components: 40 kg of cement, 80 kg of basalt gravel with a continuous gradation of 5 - 20 mm in particle size, 60 kg of manufactured sand with a continuous gradation of 0.2 - 4 mm in particle size, 25 kg of mineral materials, 1 kg of polyethylene powder, 0.1 kg of dispersant polyethylene glycol, 3 kg of modified waste fibers prepared in Preparation Example 1, and the water - binder ratio is 0.4; where the mineral materials consist of 20 kg of fly ash and 5 kg of silica fume.

[0038] Example 2

[0039] A kind of concrete for water network project using waste fibers comprises the following components: 50 kg of cement, 110 kg of basalt gravel with a continuous gradation of 5 - 20 mm in particle size, 90 kg of manufactured sand with a continuous gradation of 0.2 - 4 mm in particle size, 15 kg of mineral materials, 0.3 kg of polybutene powder, 1.2 kg of dispersant hydroxypropyl methylcellulose, 10 kg of modified waste fibers prepared in Preparation Example 1, and the water - binder ratio is 0.3; where the mineral materials consist of silica fume.

[0040] Example 3

[0041] A kind of concrete for waste fiber water network project, comprising the following components: 60 kg of cement, 80 kg of basalt gravel with a continuous gradation of 5 - 20 mm in particle size, 70 kg of manufactured sand with a continuous gradation of 0.2 - 4 mm in particle size, 18 kg of mineral materials, 0.6 kg of polypropylene powder, 1 kg of dispersant hydroxypropyl methylcellulose, 10 kg of modified waste fibers prepared in Preparation Example 1, and a water-binder ratio of 0.2; wherein the mineral materials are composed of 10 kg of silica fume and 8 kg of carbide slag.

[0042] Example 4

[0043] The difference from Example 3 is that the polyolefin enhancer is 0.3 kg of polypropylene powder and 0.3 kg of polyethylene powder, and the rest are the same as in Example 3.

[0044] Example 5

[0045] The difference from Example 4 is that the mineral materials are composed of 9 kg of fly ash and 9 kg of carbide slag, and the rest are the same as in Example 4.

[0046] Example 6

[0047] The difference from Example 5 is that the modified waste fibers prepared in Preparation Example 2 are selected, and the rest are the same as in Example 5.

[0048] Example 7

[0049] The difference from Example 5 is that the modified waste fibers prepared in Preparation Example 3 are selected, and the rest are the same as in Example 6.

[0050] Example 8

[0051] The difference from Example 5 is that the modified waste fibers prepared in Preparation Example 4 are selected, and the rest are the same as in Example 5.

[0052] Comparative Example 1 The difference from Example 8 is that the water-binder ratio is 0.48, and the rest are the same as in Example 8.

[0053] Comparative Example 2 The difference from Example 8 is that the polyolefin enhancer is replaced with manufactured sand in equal amount, and the rest are the same as in Example 8.

[0054] Comparative Example 3 The difference from Example 8 is that the modification step of the waste fibers is omitted, and the waste fibers are directly used, and the rest are the same as in Example 8.

[0055] Comparative Example 4 The difference from Example 8 is that the modified waste fibers are prepared through the following steps: removing impurities from the waste fibers (glass fibers and polypropylene fibers), followed by ultrasonic cleaning, and then performing plasma irradiation at a power of 80 W for 20 min; the mass ratio of glass fibers to polypropylene fibers is 1:1, the lengths of the glass fibers and polypropylene fibers are 20 - 30 mm, and the diameters are ≤1 mm; the other raw material components are the same as those in Example 8.

[0056] Examples 1 - 8 and Comparative Examples 1 - 4 were cured according to GB / T 50081 - 2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the compressive strength of the concrete specimens at 28 days was tested, and the specimens were placed under the condition of -20°C for the splitting tensile strength test to determine the tensile strength of the concrete at low temperature. The results are recorded in Table 1.

[0057] Table 1 Compressive strength / MPa Tensile strength / MPa Example 1 60.62 4.65 Example 2 68.71 5.22 Example 3 74.18 5.73 Example 4 76.45 5.98 Example 5 78.14 6.15 Example 6 75.03 5.89 Example 7 75.97 5.95 Example 8 79.59 6.32 Comparative example 1 42.57 3.08 Comparative example 2 61.21 4.25 Comparative example 3 56.24 3.92 Comparative example 4 59.63 4.37 From Examples 1 to 8 and in combination with Table 1, it can be seen that the concrete material prepared by the present application not only has excellent compressive strength but also has excellent low-temperature tensile performance.

[0058] From Example 8 and Comparative Example 1 and in combination with Table 1, it can be seen that changing the water-binder ratio of the system and having too large a water-binder ratio will cause a significant decline in the mechanical properties of the concrete material. Therefore, the water-binder ratio of the concrete material must be strictly controlled to effectively improve the comprehensive performance of the concrete.

[0059] From Example 8 and Comparative Example 2 and in combination with Table 1, it can be seen that in Comparative Example 2, when the polyolefin enhancer was equally replaced with manufactured sand, the compressive strength of the concrete material was poor and the low-temperature tensile performance decreased significantly. This is because the granular polyolefin enhancer forms an energy dissipation network in the matrix, absorbs the internal stress of the concrete, inhibits the propagation of microcracks, the polyolefin enhancer can cooperate with the plasticizer, and the ester groups in dibutyl phthalate and dioctyl sebacate form a physical adsorption layer on the surface of the polyolefin to promote stress transfer and form a toughening network. The polyolefin enhancer can also cooperate with the dispersant to stabilize the suspension of polymer powder through steric hindrance effect, prevent sedimentation or agglomeration during stirring, and the hydrophilic chain segments of hydroxypropyl methylcellulose wrap the polyolefin enhancer to enhance the wettability with the cement paste, jointly optimizing the microstructure of the material and significantly improving the comprehensive performance of the concrete.

[0060] It can be seen from Example 8 and Comparative Examples 3-4 in combination with Table 1 that without modifying the waste fibers or changing some of the modification steps, the mechanical properties of concrete cannot be effectively improved. This is because the silane coupling agent contains ethoxy groups and amino groups. The ethoxy groups can be hydrolyzed to form silanols, which bond with the groups on the fiber surface. The amino groups have strong reactivity and can form coordination bonds with calcium ions in the cement hydration products, or form hydrogen bonds with the hydroxyl groups in the C-S-H gel. They can also promote the oriented growth of cement hydration products on the fiber surface, reduce pores, and enhance the mechanical bite force. The silane bridges the fiber and the cement matrix, and the covalent bonds and hydrogen bonds act synergistically, improving the stress transfer efficiency between the fiber and the matrix, delaying crack propagation, and enhancing the durability of concrete. At the same time, when plasma irradiation is used, high-energy particles bombard the fiber surface, breaking the chemical bonds on the fiber surface (such as C-H, C-C), generating active sites (free radicals), increasing the surface energy, and playing a role in activating the surface. Under the action of the plasticizer, functional groups are further grafted, significantly improving the interfacial properties between the waste fiber and the polymer matrix, thereby enhancing the compressive strength and low-temperature tensile properties of the material.

[0061] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A waste fiber water network engineering concrete, characterized in that: The invention comprises the following components in parts by weight: 40-60 parts of cement, 130-200 parts of aggregate, 15-25 parts of mineral material, 0.3-1 parts of polyolefin reinforcing agent, 0.1-1.2 parts of dispersant, 3-10 parts of modified waste fiber, and a water-binder ratio of ≤0.4; The modified waste fiber is prepared by the following steps: washing the waste fiber and then immersing it in a silane coupling agent solution, heating it for reaction, then adding a plasticizer and performing plasma irradiation.

2. The waste fiber water network engineering concrete according to claim 1 is characterized by: The silane coupling agent solution is an ethanol solution containing a silane coupling agent, and the concentration of the ethanol solution is 0.5-2%.

3. The waste fiber water network engineering concrete according to claim 2 is characterized by: The temperature-raising reaction conditions are: raising the temperature to 50-60° C. and reacting for 1-2 hours.

4. The waste fiber water network engineering concrete according to claim 1, characterized in that: The aggregate includes basalt crushed stone with a particle size of 5-20 mm and continuously graded machine-made sand with a particle size of 0.2-4 mm.

5. The waste fiber water network engineering concrete according to claim 1, characterized in that: The plasticizer is one of dibutyl phthalate and dioctyl sebacate.

6. The waste fiber water network engineering concrete according to claim 1, characterized in that: The dispersant is one of polyethylene glycol and hydroxypropyl methylcellulose.

7. The waste fiber water network engineering concrete according to claim 1 is characterized by: The polyolefin reinforcing agent is one or both of polyethylene powder and polypropylene powder.

8. The waste fiber water network engineering concrete according to claim 1 is characterized by: The mineral material includes at least one of fly ash, silica ash and carbide slag.

9. The waste fiber water network engineering concrete according to claim 1, characterized in that: The waste fibers include at least one of glass fibers, polyester fibers, polyethylene fibers, and polypropylene fibers.