Polyurea sandwich concrete composite pipeline and preparation method thereof

Abstract

The invention provides a polyurea sandwich concrete composite pipeline and a preparation method thereof. The polyurea sandwich concrete composite pipeline sequentially comprises a polyurea lining layer, a concrete pipe core, a carbon fiber restraint layer and a polyurea protective layer from inside to outside. The preparation method comprises the following steps that a formwork is erected, concrete pouring is conducted, and the concrete pipe core is obtained after curing; winding a carbon fiber rope on the outer surface of the concrete pipe core to form a carbon fiber restraint layer; constructing a polyurea lining layer on the inner surface of the concrete pipe core; and constructing a polyurea protective layer on the outer surfaces of the concrete pipe core and the carbon fiber restraint layer, and curing to obtain the polyurea sandwich concrete composite pipeline. The polyurea sandwich concrete composite pipeline provided by the invention is light in weight, high in strength and excellent in impermeability and corrosion resistance, the construction difficulty in the pipeline transportation and laying process can be reduced, the service life of the pipeline is prolonged, the safety of the pipeline is improved, and the construction and maintenance cost of a municipal drainage pipe network is reduced; and the preparation method is simple.

Description

Technical Field

[0001] The invention relates to the technical field of concrete composite pipes, and in particular to a polyurea sandwich concrete composite pipe and a preparation method thereof. Background Art

[0002] At present, the types of pipes used in my country's municipal drainage network mainly include plastic pipes, concrete pipes and reinforced concrete pipes. Among them, pipes made of concrete or reinforced concrete have higher rigidity than plastic pipes and are the most widely used in practice.

[0003] In actual applications, in order to ensure the bearing capacity of concrete pipes or reinforced concrete pipes, the pipe wall thickness must meet certain design requirements, resulting in a large weight of the pipe itself, and many inconveniences in transportation and laying construction. On the other hand, under the long-term influence of water scouring, alternating changes in temperature and humidity, and the erosion of acidic substances and anaerobic microorganisms in rainwater and sewage, the concrete substrate will be gradually corroded and damaged. When the pipe body becomes thinner and cracked, it will not only cause leakage, but also collapse and sink due to reduced bearing capacity, inducing a series of safety problems such as soil and water pollution and road collapse. Although the anti-seepage and anti-corrosion properties of concrete pipes can be improved by setting up protective layers or protective patches, the problem of the heavy weight of the pipe still exists, and the protective layer or protective patch is generally seen to fall off during use.

[0004] With the help of existing pipeline non-excavation repair technologies such as in-situ curing method, spraying method, mechanical spiral winding method, etc., concrete pipelines that have already suffered from corrosion and cracking diseases can be reinforced and repaired, but the repair process affects the normal use of the pipeline, and secondary damage may occur during the subsequent service process, increasing the time cost and economic cost of maintenance. In order to reduce the difficulty of construction and increase the service life of the pipeline, the prior art proposes a concrete composite pipeline. For example, the existing Chinese patent document CN101270835A discloses a concrete composite pipeline, which includes a concrete layer, and the inner wall of the concrete layer is provided with a glass fiber reinforced plastic layer. A bonding layer or a quartz sand layer is also provided between the glass fiber reinforced plastic layer and the concrete layer. The concrete pipeline has high corrosion resistance. Since the inner wall of the pipeline adopts a glass fiber reinforced plastic layer, the composite pipeline also has the characteristics of low flow resistance, but its own weight is still relatively large.

[0005] The present invention intends to develop a lightweight, high-strength concrete composite pipe with excellent anti-seepage and corrosion resistance, which is intended to reduce the construction difficulty during pipeline transportation and laying, improve the service life and safety of the pipeline, and reduce the construction and maintenance costs of the municipal drainage network. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a polyurea sandwich concrete composite pipe and a preparation method thereof. The polyurea sandwich concrete composite pipe provided by the present invention is lightweight, high-strength and has excellent anti-seepage and corrosion resistance, can reduce the construction difficulty during pipeline transportation and laying, improve the service life and safety of the pipeline, and reduce the construction and maintenance cost of the municipal drainage network. It can solve the problems of heavy weight, poor anti-seepage and weak corrosion resistance of concrete or reinforced concrete pipes in underground drainage network systems in the prior art; and its preparation method is simple.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a polyurea sandwich concrete composite pipe, wherein the polyurea sandwich concrete composite pipe comprises, from the inside to the outside, a polyurea lining layer, a concrete pipe core, a carbon fiber constraining layer and a polyurea protective layer; the preparation method comprises the following steps:

[0009] S1, supporting the formwork and pouring concrete, and obtaining the concrete pipe core after curing;

[0010] S2, winding carbon fiber ropes on the outer surface of the concrete pipe core to form a carbon fiber constraint layer;

[0011] S3, constructing a polyurea lining layer on the inner surface of the concrete pipe core;

[0012] S4. Constructing a polyurea protective layer on the outer surface of the concrete pipe core and the carbon fiber constraining layer, and obtaining the polyurea sandwich concrete composite pipe after curing.

[0013] Further,

[0014] During the pouring of concrete, a through hole is reserved at each end of the concrete pipe core, with a hole diameter of 2 to 5 mm and a distance of 1 to 2 cm from the boundaries of both ends;

[0015] The carbon fiber rope passes through the through hole at one end of the concrete pipe core. After one end of the carbon fiber rope is knotted and fixed, the other end is continuously wound around the outer surface of the concrete pipe core in an evenly spaced spiral manner to the through hole at the other end of the concrete pipe core, and the carbon fiber rope is passed through the through hole at the other end and knotted and fixed.

[0016] Furthermore, when the carbon fiber rope is wound, the adjacent spacing is 5 to 10 mm.

[0017] Preferably, the spiral is arranged at an angle with the radial surface of the pipeline. Usually, the angle between the spiral and the radial surface of the pipeline is 1° to 3°, and is generally set to 1°.

[0018] Furthermore, the wall thickness of the concrete pipe core is 1 / 3 to 2 / 3 of the wall thickness of a conventional concrete pipe of the same size.

[0019] Furthermore, the diameter of the carbon fiber rope is 1 to 4 mm;

[0020] Furthermore, the polyurea lining layer has a designed thickness of 2 to 10 mm;

[0021] The thickness of the polyurea protective layer is 2-5 mm greater than the diameter of the carbon fiber rope, ensuring that the carbon fiber constraint layer is not exposed, and is consistent with the thickness of the polyurea lining layer.

[0022] Furthermore, the concrete strength grade of the concrete pipe core is C40 or above, and the reinforced concrete pipe core is obtained by configuring a single-layer or multi-layer steel bar skeleton.

[0023] Furthermore, the polyurea material forming the polyurea lining layer and the polyurea protective layer includes component A and component B, wherein component A includes the following raw materials in parts by weight: 31 to 55 parts of isocyanate, 45 to 69 parts of polyol, and 2 to 10 parts of silane coupling agent; component B includes the following raw materials in parts by weight: 40 to 80 parts of polyaspartic acid ester resin, 2 to 5 parts of defoamer, 1 to 6 parts of leveling agent, 1 to 5 parts of antioxidant, and 40 to 65 parts of color filler; when used, the mass ratio of component A to component B is 2:1 to 1:1.

[0024] Preferably, the isocyanate is at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (4,4'HMDI), p-phenylene diisocyanate (PPDI), hexamethylene diisocyanate (HDI) or oligomers thereof (HDI trimer).

[0025] Preferably, the polyol is at least one of polyoxypropylene ether polyol, polyester polyol, and plant-based refined polyol.

[0026] More preferably, the polyoxypropylene ether polyol is selected from at least one of polyoxypropylene ether diol and polyoxypropylene ether triol having molecular weights of 1000, 2000 and 3000 respectively.

[0027] More preferably, the polyester polyol is selected from at least one of polycaprolactone diol and polycarbonate diol having molecular weights of 1000 and 2000 respectively.

[0028] More preferably, the plant-based refined polyol is at least one selected from castor oil and its modified products.

[0029] Preferably, the silane coupling agent is at least one of γ-aminopropyltriethoxysilane (KH-550), γ-glycidyloxypropyltrimethoxysilane (KH-560), N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and bis(3-trimethoxysilylpropyl)amine.

[0030] Preferably, the polyaspartic acid ester resin is selected from at least one of polyaspartic acid ester resin Desmophen NH1420, polyaspartic acid ester resin Desmophen NH 1520, polyaspartic acid ester resin Desmophen NH 1220, polyaspartic acid ester resin F420, polyaspartic acid ester resin F520 and polyaspartic acid ester resin F220.

[0031] The above-mentioned polyaspartic acid ester resins are all selected from the commercially available products of the corresponding models of Covestro.

[0032] Preferably, the defoaming agent is at least one of BYK-065 (BASF Chemical Co., Ltd.), BYK-A535 (BASF Chemical Co., Ltd.), Deqian-6800 (Deqian (Shanghai) Chemical Co., Ltd.), FoamStar ST2410AC (BASF Chemical Co., Ltd.), etc.

[0033] The above defoamers are all known commercial products of the corresponding manufacturers, among which: BYK-065 and BYK-A535 are chemically composed of foam-breaking polysiloxane solutions, the main component of Deqian-6800 is a polysiloxane mixture containing hydrophobic particles, and FomaStartST2410AC is a new mineral oil-based compound.

[0034] Preferably, the leveling agent is at least one of BYK-350 (BYK Chemical Company, Germany), BYK-356 (BYK Chemical Company, Germany), BYK-361 (BYK Chemical Company, Germany), etc.

[0035] The above-mentioned leveling agents are all commercially available products of corresponding manufacturers, and their main chemical components are polyacrylates.

[0036] Preferably, the antioxidant is at least one of commercially available antioxidant 1076 (BASF Chemical Co., Ltd.), antioxidant 1098 (BASF Chemical Co., Ltd.), antioxidant 1330 (BASF Chemical Co., Ltd.), etc.

[0037] The above antioxidants are all commercially available products from corresponding manufacturers.

[0038] Preferably, the pigment filler is at least one of rutile titanium dioxide, carbon black, 400 mesh talc powder, 1250 mesh heavy calcium powder, and 1250 mesh wollastonite powder.

[0039] Furthermore, the polyurea lining layer and the polyurea protective layer are constructed by applying the polyurea material through high-pressure airless spraying or manual brushing, and are continuously and smoothly transitioned on the end surface of the concrete pipe core.

[0040] Furthermore, the tensile strength of the constructed polyurea lining layer and polyurea protective layer is not less than 40 MPa, the interfacial bonding strength with concrete is not less than 3.0 MPa, it is impermeable under 0.4 MPa water pressure, and does not deteriorate in an acid corrosion environment.

[0041] In a second aspect, the present invention also provides a polyurea sandwich concrete composite pipe obtained by the above preparation method. Specifically, the polyurea sandwich concrete composite pipe comprises a four-layer structure, which includes a polyurea lining layer, a concrete core, a carbon fiber constraining layer and a polyurea protective layer from the inside to the outside.

[0042] Beneficial effects of the present invention:

[0043] 1. The polyurea sandwich concrete composite pipe provided by the present invention generally has an inner diameter of 300 to 3500 mm, and its load-bearing performance can reach or exceed that of conventional concrete or reinforced concrete pipes of the same size, but can reduce the amount of concrete used, and its own weight is reduced by about 1 / 3 to 2 / 3 compared with concrete or reinforced concrete pipes of the same specifications, saving raw materials while also reducing the difficulty of transportation and laying construction.

[0044] 2. In the polyurea sandwich concrete composite pipe of the present invention, the polyurea lining layer, the polyurea protective layer and the carbon fiber constraining layer form an integral body with the concrete pipe core, and the high tensile strength and good toughness of the polyurea and carbon fiber materials are utilized to ensure that the bearing performance of the polyurea sandwich concrete composite pipe reaches or exceeds that of conventional concrete or reinforced concrete pipes of the same size.

[0045] 3. The polyurea sandwich concrete composite pipe of the present invention has a polyurea lining layer and a polyurea protective layer that completely wrap the concrete pipe core, and the polyurea material has good impermeability and strong corrosion resistance. In particular, the polyurea material used in the polyurea lining layer and the polyurea protective layer of the present invention is a two-component system. The A and B components can be used after being accurately weighed and stirred evenly, and the operation is simple and convenient; the interfacial bonding strength between the polyurea material layer and the concrete is not less than 3.0MPa; the adhesion retention rate in a long-term immersion environment is greater than 80%; the gel time of the polyurea material is 20-40 minutes, and the surface is dry in 1-2 hours. It is less affected by environmental humidity, and the coating is dense, smooth, and has no cracks when bent, which can reduce the resistance to liquid circulation; the tensile strength is not less than 40MPa, and it is impermeable under a water pressure of 0.4MPa, and does not deteriorate in an acid corrosion environment. Therefore, in practical applications, it can better resist the leakage or corrosion of rainwater and sewage, and the polyurea lining layer is smooth and flat, has good hydrophobicity, is conducive to the flow of water in the pipe, and can extend the service life of the pipe while also improving the water delivery capacity.

[0046] 4. The polyurea sandwich concrete composite pipe of the present invention has a high bonding strength between the polyurea lining layer and the polyurea protective layer and the concrete pipe core, which can better avoid the failure of the lining layer or the protective layer due to interface debonding, and has a better long-term protection effect.

[0047] 5. The polyurea sandwich concrete composite pipe of the present invention has a smooth and flat polyurea protective layer with good wear resistance. When the pipe jacking method is used for construction and laying, it helps to reduce the resistance caused by friction during the pipe jacking process, making construction more convenient.

[0048] In summary, the polyurea sandwich concrete composite pipe provided by the present invention is lightweight, high-strength and has excellent anti-seepage and corrosion resistance, can reduce the construction difficulty during pipeline transportation and laying, improve the service life and safety of the pipeline, and reduce the construction and maintenance costs of the municipal drainage network; and the preparation method is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments or technical points of the present invention, the drawings required for use in the embodiments or prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For other technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0050] Figure 1 The present invention provides a schematic flow chart of a method for preparing a polyurea sandwich concrete composite pipe.

[0051] Figure 2 This is a schematic diagram of the radial cross-sectional structure of the polyurea sandwich concrete composite pipe provided by the present invention.

[0052] Figure 3This is a schematic diagram of the hierarchical structure of the polyurea sandwich concrete composite pipe provided by the present invention.

[0053] Figure 4 A schematic diagram of the winding method of the carbon fiber rope in the polyurea sandwich concrete composite pipe provided in an embodiment of the present invention.

[0054] Figure 5 This is a comparison chart of the bearing capacity test results of the polyurea sandwich concrete composite pipe provided by an embodiment of the present invention and a conventional reinforced concrete pipe.

[0055] Explanation of reference numerals: 1 - concrete core; 101 , through hole; 2 - carbon fiber constraining layer; 3 - polyurea lining layer; 4 - polyurea protective layer. DETAILED DESCRIPTION

[0056] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical points and 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 making creative work are within the scope of protection of the present invention.

[0058] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, front, back, left, right, inside, outside, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the characteristic posture changes, the directional indication will also change accordingly.

[0059] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0060] In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be purchased commercially.

[0061] Example 1

[0062] like Figures 1 to 4 As shown, this embodiment provides a polyurea sandwich concrete composite pipe, which includes, from the inside to the outside, a polyurea lining layer 3, a concrete pipe core 1, a carbon fiber constraining layer 2 and a polyurea protective layer 4. It is prepared by the following preparation method:

[0063] S1, formwork and concrete pouring, after curing, a concrete pipe core 1 is obtained. The wall thickness of the concrete pipe core 1 is designed to be 1 / 3 to 2 / 3 of the wall thickness of a conventional concrete pipe of the same size. In this embodiment, the inner diameter of the concrete pipe core 1 is 510 mm and the wall thickness is 25 mm. The concrete strength grade of the concrete pipe core 1 is C40 or above, and the reinforced concrete pipe core 1 is obtained by configuring a single-layer steel skeleton. The production of the steel skeleton meets the requirements of the national standard GB / T 11836-2023.

[0064] During the pouring of concrete, a through hole 101 is reserved at each end of the concrete tube core 1, and the hole diameter is generally set to 2-5 mm, and the distance from the two end boundaries is 1-2 cm. In this embodiment, the hole diameter of the through hole 101 is 3 mm, and the distance from the two end boundaries of the concrete tube core 1 is 1 cm.

[0065] S2, wind the carbon fiber rope on the outer surface of the concrete tube core 1 to form a carbon fiber constrained layer 2. Specifically, the concrete tube core 1 is placed vertically, the carbon fiber rope is passed through the through hole 101 at the upper part of the concrete tube core 1 and is tied and fixed, and then the carbon fiber rope is wound around the concrete tube core 1 at equal intervals, and after reaching the bottom, it is passed through another through hole 101 and is tied and fixed to obtain a structure as shown in FIG. Figure 2 As shown. When winding the carbon fiber rope, the adjacent spacing is 5 to 10 mm; the diameter of the carbon fiber rope is 1 to 4 mm. As a preferred embodiment, the carbon fiber rope is spirally wound on the outer surface of the concrete pipe core 1, the winding angle with the radial direction of the pipe is 1°, and the winding spacing of adjacent carbon fiber ropes is 10 mm. The diameter of the carbon fiber rope used is 2 mm. After the carbon fiber rope is knotted and fixed, the excess part is cut off.

[0066] S3, constructing a polyurea lining layer 3 on the inner surface of the concrete pipe core 1; the designed thickness of the polyurea lining layer 3 is 2 to 10 mm. As a preferred embodiment, in this embodiment, the thickness of the polyurea lining layer 3 is 5 mm.

[0067] S4, constructing a polyurea protective layer 4 on the outer surface of the concrete pipe core 1 and the carbon fiber constraining layer 3, and obtaining the polyurea sandwich concrete composite pipe after curing. The thickness of the polyurea protective layer 4 is 2 to 5 mm larger than the diameter of the carbon fiber rope to ensure that the carbon fiber constraining layer 3 is not exposed, and is consistent with the thickness of the polyurea lining layer 2. In this embodiment, the thickness of the polyurea protective layer 4 is 5 mm.

[0068] The polyurea material for constructing the polyurea lining layer 2 and the polyurea protective layer 4 of the present invention comprises component A and component B, wherein component A comprises the following raw materials in parts by weight: 31 to 55 parts of isocyanate, 45 to 69 parts of polyol, and 2 to 10 parts of silane coupling agent; component B comprises the following raw materials in parts by weight: 40 to 80 parts of polyaspartic acid ester resin, 2 to 5 parts of defoamer, 1 to 6 parts of leveling agent, 1 to 5 parts of antioxidant, and 40 to 65 parts of color filler; when used, the mass ratio of component A to component B is 2:1 to 1:1.

[0069] As a preferred embodiment, this embodiment provides a polyurea material for forming a polyurea lining layer 2 and a polyurea protective layer 4 and a preparation method thereof, wherein the polyurea material comprises component A and component B.

[0070] Component A includes the following raw materials in parts by weight: 36 parts of MDI-50 (diphenylmethane diisocyanate), 62 parts of DL-2000 (polyoxypropylene ether glycol with a molecular weight of 2000), and 2 parts of KH-560 (γ-glycidyloxypropyltrimethoxysilane). The preparation method of component A is as follows: weigh the above-mentioned parts by weight of polyether polyol DL-2000, add the polyether polyol DL-2000 into a reaction kettle, start stirring; heat to 110°C. Use a vacuum pump to evacuate to -0.1MPa to dehydrate and remove moisture from the raw materials. Until the moisture content of the raw material drops below 0.5 parts per million; the liquid material temperature is cooled to 55°C; the isocyanate MDI-50 is weighed and added to the reactor, stirred and dispersed for 0.5 hours, slowly heated to 85°C for reaction for 2 hours, and the NCO value is detected by di-n-butylamine titration; when the NCO value reaches the design value of 100%, the silane coupling agent KH-560 is weighed and added to the reactor, and kept warm for 0.5 hours; the liquid material is cooled to 55°C, and the material is discharged to obtain the A component material. The NCO% design value in the scheme is the theoretical NCO value calculated by formula design.

[0071] Component B includes the following raw materials in parts by weight: 62 parts of polyaspartic acid resin F420 (Covestro), 1 part of antioxidant 1076 (BASF Chemical Co., Ltd.), 1 part of defoamer Deqian-6800 (Deqian (Shanghai) Chemical Co., Ltd.), 1 part of leveling agent BYK-356 (BYK Chemical Company, Germany), and 35 parts of pigments and fillers; the pigments and fillers are composed of 1 part of white slurry, 0.2 parts of black slurry, 20 parts of 400 mesh talc, 7 parts of 1250 mesh heavy calcium, and 6.8 parts of 1250 mesh wollastonite powder. The preparation method of component B is as follows: weigh the above-mentioned polyaspartic acid resin F420 and antioxidant 1076 in parts by weight and add them to a vacuum stirring kettle, start stirring, and heat the liquid to 110°C; add the pigments and fillers to the vacuum stirring kettle and stir for 0.5 hours; maintain 110°C, and vacuum pump to -0.1MPa to dehydrate and remove moisture from the raw materials. Until the moisture content of the raw material drops below 0.5 parts per million; add the above-mentioned defoaming agent Deqian-6800 and leveling agent BYK-378 and stir for 0.5 hours; cool to 55°C and discharge the material to obtain component B material.

[0072] When this embodiment is used, the mass ratio of component A to component B is 2:1.

[0073] The inner surface of the concrete pipe core 1 is continuously sprayed over the entire cross section by using a dedicated high-pressure airless spraying device to construct a polyurea inner lining layer 2, which is cured at room temperature for 40 minutes. The outer surfaces of the concrete pipe core 1 and the carbon fiber constraining layer 3 are continuously sprayed to construct a polyurea protective layer 4, which is cured at room temperature for 40 minutes.

[0074] The interfacial bonding strength between the polyurea lining layer 2 and the polyurea protective layer 4 constructed by the embodiment of the present invention and the concrete is not less than 3.0MPa; the adhesion retention rate in a long-term immersion environment is greater than 80%; the gel time of the polyurea material is 20 to 40 minutes, and the surface is dry in 1 to 2 hours. It is less affected by the environmental humidity, and the coating is dense, smooth, and has no cracks when bent, which can reduce the resistance to liquid circulation; the tensile strength is not less than 40MPa, and it is impermeable under 0.4MPa water pressure and does not deteriorate in an acid corrosion environment. The determination of the various performance parameters described is measured using existing conventional measurement methods, such as the surface drying time is measured using the finger touch method in the "Determination of the Drying Time of Paint Film and Putty Film" (GB / T1728-2020). The interfacial bonding strength and the adhesion in the immersion environment can be measured by using the QJ211S electronic universal testing machine to measure the bonding characteristics of the interface between concrete and the test material.

[0075] This is due to the fact that the polyurea material used in the present invention is a two-component system, the active group of component A is an isocyanate group, and the active group of component B is an amine group. The two are mixed and reacted to generate a urea group. This molecular segment has high cohesive energy, which can give the material excellent mechanical properties; in addition, the system contains a large number of flexible segments, which can give the material excellent flexibility; finally, the isocyanate and amine groups have strong reaction selectivity and are not affected by moisture. The spraying process is used to make the formed coating more dense. In addition, components A and B can be used after being accurately weighed and stirred evenly, which is simple and convenient to operate.

[0076] In the polyurea sandwich concrete composite pipe of the present invention, the polyurea lining layer 3, the polyurea protective layer 4 and the carbon fiber constraining layer 2 form a whole with the concrete pipe core 1, and the high tensile strength and good toughness of the polyurea and carbon fiber materials are utilized to ensure that the load-bearing performance of the polyurea sandwich concrete composite pipe of the present invention is improved.

[0077] The polyurea sandwich concrete composite pipe prepared by the above method has an inner diameter of 500mm and a wall thickness of 35mm. The dead weight is reduced by about 50% compared with the conventional concrete pipe with the same inner diameter, which saves raw materials and reduces the difficulty of transportation and laying construction.

[0078] The mechanical test results show that the bearing capacity of the polyurea sandwich concrete composite pipe in this embodiment is about 25% higher than that of the conventional reinforced concrete pipe with the same inner diameter. The conventional reinforced concrete pipe used for comparison has an inner diameter of 500 mm, a wall thickness of 50 mm, a concrete strength grade of C40 and above, and contains a single-layer steel skeleton, and the manufacture of the steel skeleton meets the requirements of the national standard GB / T 11836-2023.

[0079] The polyurea sandwich concrete composite pipe of the present invention has a polyurea lining layer 3 and a polyurea protective layer 4 that completely wrap the concrete pipe core 1, and the polyurea material has good impermeability and strong corrosion resistance. In particular, the polyurea material used in the polyurea lining layer and the polyurea protective layer of the present invention is a two-component system. The A and B components can be used after being accurately weighed and stirred evenly, and the operation is simple and convenient; the interface bonding strength between the polyurea material layer and the concrete is not less than 3.0MPa; the adhesion retention rate in a long-term immersion environment is greater than 80%; the gel time of the polyurea material is 20 to 40 minutes, and the surface is dry in 1 to 2 hours. It is less affected by the environmental humidity, and the coating is dense, smooth, and has no cracks when bent, which can reduce the resistance to liquid circulation; the tensile strength is not less than 40MPa, and it is impermeable under a water pressure of 0.4MPa, and does not deteriorate in an acid corrosion environment. Therefore, in practical applications, it can better resist the leakage or corrosion of rainwater and sewage, and the polyurea lining layer is smooth and flat, has good hydrophobicity, is conducive to the flow of water in the pipe, and can extend the service life of the pipe while also improving the water delivery capacity.

[0080] In the polyurea sandwich concrete composite pipe of the present invention, the polyurea lining layer 3 and the polyurea protective layer 4 have high bonding strength with the concrete pipe core 1, which can better avoid the failure of the lining layer or the protective layer due to interface debonding, and has a better long-term protection effect.

[0081] The polyurea sandwich concrete composite pipe of the present invention has a smooth and flat polyurea protective layer with good wear resistance. When the pipe jacking method is used for construction and laying, it helps to reduce the resistance caused by friction during the pipe jacking process, making the construction more convenient.

[0082] In summary, the polyurea sandwich concrete composite pipe provided by the present invention is lightweight, high-strength and has excellent anti-seepage and corrosion resistance, can reduce the construction difficulty during pipeline transportation and laying, improve the service life and safety of the pipeline, and reduce the construction and maintenance costs of the municipal drainage network; and the preparation method is simple.

[0083] The above descriptions are only some preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a polyurea sandwich concrete composite pipe, characterized in that: The polyurea sandwich concrete composite pipe comprises, from the inside to the outside, a polyurea lining layer, a concrete pipe core, a carbon fiber constraining layer and a polyurea protective layer; and the preparation method thereof comprises the following steps: S1, supporting the formwork and pouring concrete, and obtaining the concrete pipe core after curing; S2, winding carbon fiber ropes on the outer surface of the concrete pipe core to form a carbon fiber constraint layer; S3, constructing a polyurea lining layer on the inner surface of the concrete pipe core; S4. Constructing a polyurea protective layer on the outer surface of the concrete pipe core and the carbon fiber constraining layer, and obtaining the polyurea sandwich concrete composite pipe after curing.

2. The method for preparing a polyurea sandwich concrete composite pipe according to claim 1, characterized in that: During the pouring of concrete, a through hole is reserved at each end of the concrete pipe core, with a hole diameter of 2 to 5 mm and a distance of 1 to 2 cm from the boundaries of both ends; The carbon fiber rope passes through the through hole at one end of the concrete pipe core. After one end of the carbon fiber rope is knotted and fixed, the other end is continuously wound around the outer surface of the concrete pipe core in an evenly spaced spiral manner to the through hole at the other end of the concrete pipe core, and the carbon fiber rope is passed through the through hole at the other end and knotted and fixed.

3. The method for preparing a polyurea sandwich concrete composite pipe according to claim 2, characterized in that: When winding the carbon fiber rope, the adjacent spacing of the spirals is 5 to 10 mm; and the spirals are set at an angle to the radial surface of the pipe.

4. The method for preparing a polyurea sandwich concrete composite pipe according to claim 3, characterized in that: The setting angle between the spiral and the radial surface of the pipe is 1° to 3°.

5. The method for preparing a polyurea sandwich concrete composite pipe according to claim 1, characterized in that: The wall thickness of the concrete pipe core is 1 / 3 to 2 / 3 of the wall thickness of a conventional concrete pipe of the same size.

6. The method for preparing a polyurea sandwich concrete composite pipe according to claim 1, characterized in that: The diameter of the carbon fiber rope is 1 to 4 mm; The designed thickness of the polyurea lining layer is 2 to 10 mm; The thickness of the polyurea protective layer is 2-5 mm greater than the diameter of the carbon fiber rope, ensuring that the carbon fiber constraint layer is not exposed, and is consistent with the thickness of the polyurea lining layer.

7. The method for preparing a polyurea sandwich concrete composite pipe according to claim 1, characterized in that: The concrete strength grade of the concrete pipe core is C40 or above, and the reinforced concrete pipe core is obtained by configuring a single-layer or multi-layer steel bar skeleton.

8. The method for preparing a polyurea sandwich concrete composite pipe according to claim 1, characterized in that: The polyurea material for forming the polyurea lining layer and the polyurea protective layer comprises component A and component B, wherein component A comprises the following raw materials in parts by weight: 31 to 55 parts of isocyanate, 45 to 69 parts of polyol, and 2 to 10 parts of silane coupling agent; component B comprises the following raw materials in parts by weight: 40 to 80 parts of polyaspartic acid ester resin, 2 to 5 parts of defoamer, 1 to 6 parts of leveling agent, 1 to 5 parts of antioxidant, and 40 to 65 parts of color filler; when used, the mass ratio of component A to component B is 2:1 to 1:

1.

9. A method for preparing a polyurea sandwich concrete composite pipe as claimed in claim 8, characterized in that: The polyurea lining layer and the polyurea protective layer are constructed by using the polyurea material through a high-pressure airless spraying method or a manual brushing method, and have a continuous and smooth transition on the end surface of the concrete pipe core.

10. A polyurea sandwich concrete composite pipe prepared by the preparation method according to any one of claims 1 to 9.

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