An erosion resistant sewer pipe and method of making the same

Abstract

This invention relates to an anti-corrosion sewage pipe and its preparation method, belonging to the field of water environment management technology. The sewage pipe wall consists of an inner layer, a middle layer, and an outer layer; the inner layer is made of a highly corrosion-resistant cement-based material, the middle layer is made of a high-adhesion inorganic adhesive, and the outer layer is made of low-carbon cement concrete, with a steel mesh embedded inside the concrete as a supporting framework; the thickness ratio of the inner, middle, and outer layers is 1:(0.2-0.4):(2-5); the highly corrosion-resistant cement-based material is a cement-based material with a pH value of 9.5-11.5; the high-adhesion inorganic adhesive is a phosphorus-magnesium-based inorganic cementitious material; the inner layer of the sewage pipe has low alkalinity and good resistance to microbial and sulfate attack; the middle layer has good adhesion and firmly bonds the inner and outer layers; the outer layer is low-carbon cement concrete, whose carbon emissions are less than 50% of traditional silicate cement, thus ensuring that the sewage pipe has excellent corrosion resistance while being green, low-carbon, and environmentally friendly.

Description

Technical Field

[0001] This invention relates to an anti-corrosion sewage pipe and its preparation method, belonging to the field of water environment management technology. Background Technology

[0002] In recent years, corrosion and damage to sewage pipes have become increasingly frequent problems. The service life of sewage pipes is far shorter than their design life, and ruptures or damage can easily lead to major safety accidents. Meanwhile, the daily sewage treatment volume is constantly increasing, posing even greater challenges to sewage pipes. Sewage pipes are mainly made of plastic, metal, and reinforced concrete. Plastic pipes have low pressure resistance and cannot meet the required operating conditions; metal pipes are inherently prone to corrosion and operate in harsh environments. Therefore, reinforced concrete pipes are used in most cases. Existing reinforced concrete sewage pipes are frequently damaged due to microbial corrosion and sulfuric acid attack, leading to rebar corrosion and subsequent pipe failure.

[0003] The main forms of damage to existing reinforced concrete sewage pipes are microbial corrosion and sulfuric acid erosion. Microorganisms produce acid through the metabolism of hydrogen sulfide, which corrodes hydration products and aggregates, leading to the deterioration of component performance. Although various anti-corrosion technologies for pipelines have been proposed, such as increasing the strength grade of concrete to improve the pipe's density or applying anti-corrosion coatings to the surface, these methods can slow down the corrosion rate of reinforced concrete sewage pipes to some extent. However, the cementitious material of reinforced concrete itself is not corrosion-resistant. In a sulfuric acid-eroded environment, silicate cement generates a large amount of gypsum, calcium carbonate, calcium silicate, and ettringite, which expand in volume and weaken its strength. Therefore, starting from the design of the sewage pipe material itself for anti-corrosion is the most direct and effective means to fundamentally solve the corrosion problem of sewage pipes. Summary of the Invention

[0004] In view of the shortcomings of existing reinforced concrete sewage pipes, which are susceptible to microbial corrosion and sulfuric acid erosion leading to steel corrosion and subsequent pipe damage, one of the objectives of this invention is to provide a corrosion-resistant sewage pipe. The corrosion-resistant sewage pipe is designed with the pipe material itself in mind for corrosion protection, achieving excellent corrosion resistance while also being green, low-carbon, and environmentally friendly.

[0005] The second objective of this invention is to provide a method for preparing an anti-corrosion sewage pipe, wherein the method has simple process steps, is easy to implement, and is convenient for mass production.

[0006] The objective of this invention is achieved through the following technical solutions.

[0007] An anti-corrosion sewage pipe, wherein the pipe wall is composed of an inner layer, a middle layer and an outer layer, the inner layer is made of a highly anti-corrosion cement-based material, the middle layer is made of a highly adhesive inorganic adhesive, and the outer layer is made of low-carbon cement concrete, wherein a steel mesh is embedded in the concrete as a supporting skeleton; the thickness ratio of the inner layer, the middle layer and the outer layer is 1:(0.2~0.4):(2~5);

[0008] The highly erosion-resistant cementitious material is a cementitious material with a pH value of 9.5 to 11.5;

[0009] The high-adhesion inorganic adhesive is a phosphorus-magnesium-based inorganic cementitious material;

[0010] The low-carbon cement concrete has the following mix proportions: 30-50 kg of cement clinker, 260-320 kg of composite solid waste powder, 850-1100 kg of natural sand, 850-1100 kg of gravel, 6-16 kg of polycarboxylate superplasticizer, and 150-170 kg of water; wherein the composite solid waste powder has a specific surface area of ​​800-1200 m². 2 / kg slag, specific surface area 350~500m² 2 The mixture is prepared by mixing 1-3 kg of mineral powder, fly ash and coal gangue powder in a mass ratio of (1-3):(3-6):(1-3):(1-3) with water until homogeneous.

[0011] Preferably, the thickness ratio of the inner, middle and outer layers of the sewage pipe wall is 1:(0.2-0.3):(3-5).

[0012] Preferably, the cement-based material is composed of powder, water, polycarboxylate superplasticizer, and polyoxymethylene fiber; wherein the powder is composed of high belite-sulfoaluminate cement clinker with C2S≥40%, high alumina cement clinker, mineral powder, lithium slag powder, and fluorogypsum in a mass ratio of (3-7):(1-5):(70-85):(3-8):(10-20); the mass ratio of water to powder is (0.15-0.30):1; the dosage of polycarboxylate superplasticizer is 1-3% of the powder mass; and the volume content of polyoxymethylene fiber in the cement-based material is 0.2-2%.

[0013] More preferably, the powder is composed of high belite-sulfoaluminate cement clinker with C2S≥40%, high alumina cement clinker, mineral powder, lithium slag powder and fluorogypsum in a mass ratio of (3-7):(1-5):(72-75):5:(12-15); the mass ratio of water to powder is (0.20-0.25):1; the amount of polycarboxylate superplasticizer is 1.8-2% of the powder mass; and the volume content of polyoxymethylene fiber in the cement-based material is 0.5-1%.

[0014] Preferably, the magnesium phosphate-based inorganic cementitious material is composed of calcined magnesium oxide, composite phosphate and borate in a mass ratio of 1:(0.15-0.25):(0.04-0.10); wherein the composite phosphate is composed of phosphate and metaphosphate in a mass ratio of (4-5):1.

[0015] More preferably, the phosphorus-magnesium-based inorganic cementitious material is composed of calcined magnesium oxide, composite phosphate and borate in a mass ratio of 1:(0.20-0.25):(0.06-0.10).

[0016] More preferably, the phosphate is at least one of ammonium dihydrogen phosphate and potassium dihydrogen phosphate; the metaphosphate is any two or three of sodium tetramethonium phosphate, sodium pentamethonium phosphate and sodium hexametaphosphate.

[0017] A method for preparing the corrosion-resistant sewage pipe according to the present invention, the method comprising the following steps:

[0018] (1) Stir the high erosion-resistant cement-based material evenly to obtain cement-based grout; fill the grout into the sewage pipe mold, and demold after hardening to form the inner layer of the sewage pipe wall;

[0019] (2) Using the inner layer of the sewage pipe as a template, the high-adhesion inorganic adhesive and water are mixed evenly at a water-cement ratio of 0.08 to 0.13, and sprayed or applied to the outer surface of the inner layer of the sewage pipe wall. After hardening, the middle layer of the sewage pipe wall is formed.

[0020] (3) Using the middle layer of the sewage pipe as a template, a steel mesh is installed on the outside of the template as a supporting frame, and then low-carbon cement concrete is poured. After the concrete hardens, an outer layer of the sewage pipe with steel mesh embedded inside is formed on the outer surface of the middle layer, thus obtaining the corrosion-resistant sewage pipe.

[0021] Preferably, in step (2), the high-adhesion inorganic adhesive and water are mixed evenly at a water-cement ratio of 0.09 to 0.10.

[0022] Beneficial effects

[0023] (1) The present invention provides an anti-corrosion sewage pipe, wherein the inner layer material of the sewage pipe is a high anti-corrosion cement-based material, the middle layer material is a high-adhesion inorganic adhesive, and the outer layer material is a low-carbon cement concrete; the inner layer material has low alkalinity and good resistance to microbial erosion and sulfate erosion; the middle layer material has good adhesion performance, achieving a strong bond between the inner and outer layers; the carbon emission of the outer layer material is less than 50% of that of traditional silicate cement, making it low-carbon and environmentally friendly; the anti-corrosion sewage pipe is designed from the pipe material itself to prevent corrosion, and while having excellent corrosion resistance, it also achieves the green, low-carbon and environmentally friendly nature of the product.

[0024] (2) The present invention provides an anti-corrosion sewage pipe. The inner layer material of the sewage pipe is a low-alkalinity cement with a pH value between 9.5 and 11.5. Its hydration products are mainly ettringite, CSH and gypsum. The system contains a large number of sulfate ions, which inhibits the corrosion of sulfate ions in sulfuric acid solution to a certain extent. At the same time, there is no Ca(OH)2 in its hydration products, so the reaction of Ca(OH)2 to gypsum dihydrate will not occur. This overcomes the defect of traditional silicate cement in sulfuric acid corrosion environment, which generates a large amount of gypsum, carbon-sulfur-silicon calcium stone and ettringite, which expands in volume and thus damages the strength of sewage pipe.

[0025] (3) The present invention provides an anti-corrosion sewage pipe, wherein the high-adhesion inorganic adhesive of the middle layer material of the sewage pipe is a magnesium phosphate-based inorganic cementitious material. The bonding performance of the magnesium phosphate-based inorganic cementitious material is more than twice that of traditional silicate cement. Furthermore, the composite phosphate in the magnesium phosphate-based inorganic cementitious material is composed of phosphate and metaphosphate, which ensures that the phosphate reacts with the dead-burned magnesium oxide to contribute to the bonding strength of the system. It can also delay the hydration rate of the magnesium phosphate-based system to a certain extent through metaphosphate, thus gaining a certain amount of time for the construction process of magnesium phosphate-based cementitious materials. At the same time, it ensures that the reaction process of magnesium phosphate-based materials is more complete and sufficient, and thus exerts better interfacial bonding performance.

[0026] (4) This invention provides an anti-corrosion sewage pipe, wherein the amount of cement clinker per cubic meter of low-carbon cement concrete is 30-50 kg, which is much lower than that of ordinary silicate cement concrete. Furthermore, the low-carbon cement concrete fully utilizes ultrafine mineral powder (800-1200 mg / m³). 2 The high activity and fine powder filling effect of ( / kg slag) compared to ordinary mineral powder (350~500m) 2 The combined action of mineral powder ( / kg), fly ash, and coal gangue powder promotes the hydration and hardening of low-carbon cement concrete, contributes to the mechanical properties of low-carbon cement concrete, and ensures the compactness of low-carbon cement concrete. While ensuring mechanical properties, carbon emissions are reduced by at least 50% compared to traditional silicate cement concrete.

[0027] (5) The present invention provides a method for preparing an anti-corrosion sewage pipe. The method is simple, easy to implement, and convenient for mass production. Attached Figure Description

[0028] Figure 1 This is a structural diagram of an anti-corrosion sewage pipe according to the present invention.

[0029] Among them, 1-inner layer, 2-middle layer, 3-steel mesh, 4-outer layer. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are available from publicly available commercial sources.

[0031] Example 1

[0032] A type of corrosion-resistant sewage pipe, such as Figure 1 As shown, the sewage pipe wall consists of an inner layer 1, a middle layer 2, and an outer layer 4. The inner layer 1 is made of a high-erosion-resistant cement-based material, the middle layer 2 is made of a high-adhesion inorganic adhesive, and the outer layer 4 is made of low-carbon cement concrete. The concrete is embedded with a steel mesh 3 as a supporting skeleton. The thickness ratio of the inner layer 1, the middle layer 3, and the outer layer 4 is 1:0.2:5.

[0033] The high erosion-resistant cementitious material is a cementitious material with a pH value of 9.5. The cementitious material is composed of powder, water, polycarboxylate superplasticizer, and polyoxymethylene fiber. The powder is composed of high-belite-sulfoaluminate cement clinker with a C2S content of 45%, high-alumina cement clinker, mineral powder, lithium slag powder, and fluorogypsum in a mass ratio of 3:5:75:5:12. The mass ratio of water to powder is 0.20:1. The polycarboxylate superplasticizer is added at 2% of the powder mass. The volumetric content of polyoxymethylene fiber in the cementitious material is 0.5%.

[0034] The magnesium phosphate-based inorganic cementitious material is composed of calcined magnesium oxide, composite phosphate, and borate in a mass ratio of 1:0.20:0.06; wherein the composite phosphate is composed of phosphate and metaphosphate in a mass ratio of 4:1; the phosphate is ammonium dihydrogen phosphate, and the metaphosphate is a mixture of sodium tetramethoxyphosphate, sodium pentamethoxyphosphate, and sodium hexametaphosphate.

[0035] The low-carbon cement concrete has the following mix proportions: 30 kg cement clinker, 260 kg composite solid waste powder, 850 kg natural sand, 850 kg gravel, 6 kg polycarboxylate superplasticizer, and 150 kg water; wherein the composite solid waste powder has a specific surface area of ​​800–1200 m². 2 / kg slag, specific surface area of ​​350-500m² 2 It is a compound of mineral powder, fly ash and coal gangue powder in a mass ratio of 1:3:1:1 per kg.

[0036] A method for preparing the corrosion-resistant sewage pipe described in this embodiment includes the following steps:

[0037] (1) Stir the high erosion-resistant cement-based material evenly to obtain cement-based grout; put the grout into the sewage pipe mold, and demold it after hardening to form the inner layer 1 of the sewage pipe wall;

[0038] (2) Using the inner layer 1 of the sewage pipe as a template, the high-adhesion inorganic adhesive and water are mixed evenly at a water-cement ratio of 0.10 and sprayed onto the outer surface of the inner layer of the sewage pipe wall. After hardening, the middle layer 2 of the sewage pipe wall is formed.

[0039] (3) Using the middle layer 2 of the sewage pipe as a template, a steel mesh 3 is installed on the outside of the template as a support frame, and then low-carbon cement concrete is poured. After the concrete hardens, the outer layer 4 of the sewage pipe with steel mesh embedded inside is formed on the outer surface of the middle layer, thus obtaining the anti-corrosion sewage pipe.

[0040] According to GB / T 50082-2009 Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete, the sewage pipe prepared in this embodiment was tested. The inner layer of the sewage pipe showed good resistance to sulfuric acid corrosion, with a 28-day corrosion resistance coefficient of not less than 96.8%. The middle layer of high-adhesion inorganic adhesive showed good bonding performance, with the bonding strength between the middle layer and the inner and outer layers reaching 2.0 MPa.

[0041] Example 2

[0042] A type of corrosion-resistant sewage pipe, such as Figure 1 As shown, the sewage pipe wall consists of an inner layer 1, a middle layer 2, and an outer layer 4. The inner layer 1 is made of a high-erosion-resistant cement-based material, the middle layer 2 is made of a high-adhesion inorganic adhesive, and the outer layer 4 is made of low-carbon cement concrete. The concrete is embedded with a steel mesh 3 as a supporting skeleton. The thickness ratio of the inner layer 1, the middle layer 3, and the outer layer 4 is 1:0.3:3.

[0043] The high erosion-resistant cementitious material is a cementitious material with a pH value of 11.5. The cementitious material is composed of powder, water, polycarboxylate superplasticizer, and polyoxymethylene fiber. The powder is composed of high-belite-sulfoaluminate cement clinker with a C2S content of 42%, high-alumina cement clinker, mineral powder, lithium slag powder, and fluorogypsum in a mass ratio of 7:1:72:5:15. The mass ratio of water to powder is 0.25:1. The polycarboxylate superplasticizer content is 1.8% of the powder mass. The volumetric content of polyoxymethylene fiber in the cementitious material is 1%.

[0044] The magnesium-phosphorus-based inorganic cementitious material is composed of calcined magnesium oxide, composite phosphate, and borate in a mass ratio of 1:0.25:0.10; wherein the composite phosphate is composed of phosphate and metaphosphate in a mass ratio of 5:1; the phosphate is potassium dihydrogen phosphate, and the metaphosphate is a mixture of sodium tetramethoxyphosphate and sodium pentamethoxyphosphate.

[0045] The low-carbon cement concrete has the following mix proportions: 50 kg cement clinker, 320 kg composite solid waste powder, 1100 kg natural sand, 1100 kg gravel, 16 kg polycarboxylate superplasticizer, and 170 kg water; wherein the composite solid waste powder has a specific surface area of ​​800–1200 m². 2 / kg slag, specific surface area 350~500m² 2 The mixture is prepared by mixing 1 kg / kg mineral powder, fly ash and coal gangue powder in a mass ratio of 3:6:3:3.

[0046] A method for preparing the corrosion-resistant sewage pipe described in this embodiment includes the following steps:

[0047] (1) Stir the high erosion-resistant cement-based material evenly to obtain cement-based grout; put the grout into the sewage pipe mold, and demold it after hardening to form the inner layer 1 of the sewage pipe wall;

[0048] (2) Using the inner layer 1 of the sewage pipe as a template, the high-adhesion inorganic adhesive and water are mixed evenly at a water-cement ratio of 0.09 and applied to the outer surface of the inner layer of the sewage pipe wall. After hardening, the middle layer 2 of the sewage pipe wall is formed.

[0049] (3) Using the middle layer 2 of the sewage pipe as a template, a steel mesh 3 is installed on the outside of the template as a support frame, and then low-carbon cement concrete is poured. After the concrete hardens, the outer layer 4 of the sewage pipe with steel mesh embedded inside is formed on the outer surface of the middle layer, thus obtaining the anti-corrosion sewage pipe.

[0050] According to GB / T 50082-2009 Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete, the sewage pipe prepared in this embodiment was tested. The inner layer of the sewage pipe showed good resistance to sulfuric acid corrosion, with a 28-day corrosion resistance coefficient of not less than 97.3%. The high-adhesion inorganic adhesive in the middle layer showed good bonding performance, with the bonding strength between the middle layer and the inner and outer layers reaching 2.3 MPa.

[0051] According to the test results of Examples 1 and 2, the present invention uses a highly erosion-resistant cement-based material as the inner template to ensure the sewage pipe has good resistance to sulfuric acid erosion and corrosion resistance; it uses a phosphorus-magnesium-based inorganic cementitious material with high bonding performance as the middle layer to ensure good bonding between the inner and outer layers; and it uses low-carbon cement reinforced concrete as the outer layer, with steel mesh embedded in the outer layer as the main support structure of the sewage pipe, thus obtaining a green, low-carbon, erosion-resistant sewage pipe.

[0052] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A corrosion-resistant sewage pipe, characterized in that: The sewage pipe wall consists of an inner layer, a middle layer, and an outer layer; the inner layer is made of a high-erosion-resistant cement-based material, the middle layer is made of a high-adhesion inorganic adhesive, and the outer layer is made of low-carbon cement concrete. The concrete is internally reinforced with a steel mesh as a supporting framework; the thickness ratio of the inner, middle, and outer layers is 1:(0.2~0.4):(2~5). The highly erosion-resistant cementitious material is a cementitious material with a pH value of 9.5~11.5; The high-adhesion inorganic adhesive is a phosphorus-magnesium-based inorganic cementitious material; The low-carbon cement concrete has the following mix proportions: 30-50 kg of cement clinker, 260-320 kg of composite solid waste powder, 850-1100 kg of natural sand, 850-1100 kg of gravel, 6-16 kg of polycarboxylate superplasticizer, and 150-170 kg of water; wherein the composite solid waste powder has a specific surface area of ​​800-1200 m². 2 / kg slag, specific surface area 350~500m² 2 / kg mineral powder, fly ash and coal gangue powder are mixed evenly in a mass ratio of (1~3):(3~6):(1~3):(1~3); The cement-based material is composed of powder, water, polycarboxylate superplasticizer, and polyoxymethylene fiber; wherein the powder is composed of high belite-sulfoaluminate cement clinker with C2S≥40%, high alumina cement clinker, mineral powder, lithium slag powder, and fluorogypsum in a mass ratio of (3~7):(1~5):(70~85):(3~8):(10~20); the mass ratio of water to powder is (0.15~0.30):1; the dosage of polycarboxylate superplasticizer is 1~3% of the powder mass; and the volume content of polyoxymethylene fiber in the cement-based material is 0.2~2%. The magnesium phosphate-based inorganic cementitious material is composed of calcined magnesium oxide, composite phosphate and borate in a mass ratio of 1:(0.15~0.25):(0.04~0.10); wherein the composite phosphate is composed of phosphate and metaphosphate in a mass ratio of (4~5):

1.

2. The corrosion-resistant sewage pipe according to claim 1, characterized in that: The powder is composed of high belite-sulfoaluminate cement clinker with C2S≥40%, high alumina cement clinker, mineral powder, lithium slag powder and fluorogypsum in a mass ratio of (3~7):(1~5):(72~75):5:(12~15); the mass ratio of water to powder is (0.20~0.25):1; the dosage of polycarboxylate superplasticizer is 1.8~2% of the powder mass; in the cement-based material, the volume content of polyoxymethylene fiber is 0.5~1%.

3. The corrosion-resistant sewage pipe according to claim 1, characterized in that: The phosphorus-magnesium-based inorganic cementitious material is composed of calcined magnesium oxide, composite phosphate and borate in a mass ratio of 1:(0.20~0.25):(0.06~0.10).

4. The corrosion-resistant sewage pipe according to claim 1, characterized in that: The phosphate is at least one of ammonium dihydrogen phosphate and potassium dihydrogen phosphate; the metaphosphate is any two or three of sodium tetramethphosphate, sodium pentamethphosphate and sodium hexametaphosphate.

5. A corrosion-resistant sewage pipe according to any one of claims 1 to 4, characterized in that: The thickness ratio of the inner, middle and outer layers of the sewage pipe wall is 1:(0.2~0.3):(3~5).

6. A method for preparing an anti-corrosion sewage pipe as described in any one of claims 1 to 5, characterized in that: The method steps are as follows: (1) Stir the high corrosion-resistant cement-based material evenly to obtain cement-based grout; put the grout into the sewage pipe mold, and demold it after hardening to form the inner layer of the sewage pipe wall; (2) Using the inner layer of the sewage pipe as a template, the high-adhesion inorganic adhesive and water are mixed evenly at a water-cement ratio of 0.08~0.13, and sprayed or applied to the outer surface of the inner layer of the sewage pipe wall. After hardening, the middle layer of the sewage pipe wall is formed. (3) Using the middle layer of the sewage pipe as a template, a steel mesh is installed on the outside of the template as a support frame, and then low-carbon cement concrete is poured. After the concrete hardens, the outer layer of the sewage pipe with the steel mesh embedded inside is formed on the outer surface of the middle layer, thus obtaining the anti-corrosion sewage pipe.

7. The method for preparing an anti-corrosion sewage pipe according to claim 6, characterized in that: In step (2), the high-adhesion inorganic adhesive and water are mixed evenly at a water-cement ratio of 0.09 to 0.10.

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