A lightweight aggregate-based steam-free high-performance pipe culvert and a preparation method thereof

Abstract

The present invention discloses a lightweight aggregate-based steam-free high-performance pipe culvert and a preparation method thereof, and belongs to the technical field of concrete pipe culverts. The lightweight aggregate-based steam-free high-performance pipe culvert provided by the present invention is prepared from raw materials containing the following components, measured by unit volume mass: 300-450 kg / m of sulfur-aluminum-iron low-carbon cementitious material; 3 ; Solid waste-based lightweight aggregate 800~920 kg / m 3 ; Solid waste-based artificial sand 300~550 kg / m 3 ; Mineral admixture 0~100 kg / m 3 ; Auxiliary materials 0~50 kg / m 3 ; Water 110~160 kg / m 3 The lightweight aggregate-based steam-free high-performance pipe culvert of the present invention can be demoulded within 4 hours after molding, and the demoulding time is short, steam curing is not required, the production cost is low, and the production efficiency is high; the obtained product has high strength, good anti-seepage durability, and can utilize a high proportion of solid waste.

Description

Technical Field

[0001] The invention relates to the technical field of concrete pipe culverts, and in particular to a lightweight aggregate-based steam-curing-free high-performance pipe culvert and a preparation method thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance the understanding of the overall background of the invention and should not be necessarily regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Concrete culvert is a pipe component made of concrete, which is widely used in water conservancy, transportation and other fields. It has strong structural strength and durability and is one of the important structural forms in modern engineering construction. Concrete culverts can be divided into various types such as circular, rectangular, and trough according to their shapes and purposes of use. According to the purpose of use, they can be divided into drainage culverts, channel culverts, tunnel culverts, etc. At present, the conventional preparation method of concrete culverts is to cast concrete with ordinary silicate cement and sand and gravel aggregates. Its advantage is that the technology is relatively mature and there are various specifications to guide processing and manufacturing. However, the preparation process of existing concrete culverts has the following problems: on the one hand, its demoulding time is long, usually more than 12 hours, and the production efficiency is low; on the other hand, it requires steam curing, high energy consumption, and it uses silicate cement as the main cementing material, with a high proportion of silicate cement, and relatively high cost and carbon emissions; in addition, it is necessary to obtain sand and gravel aggregates by mining natural mines, which is not conducive to protecting the ecological environment and increases transportation costs.

[0004] Therefore, it is necessary to provide a high-performance pipe culvert having short demoulding time, no steam curing, light weight, high strength and high solid waste utilization rate and a preparation method thereof. Summary of the invention

[0005] In view of this, the present invention provides a lightweight aggregate-based, steam-free high-performance pipe culvert and a preparation method thereof. The steam-free high-performance pipe culvert of the present invention has a high solid waste utilization ratio, good construction performance, short demoulding time, no need for steaming, high product strength, and a short production cycle.

[0006] In a first aspect, the present invention provides a lightweight aggregate-based, steam-free, high-performance pipe culvert, which is prepared from raw materials comprising the following components, measured by unit volume mass:

[0007] Sulfur-aluminum-iron low-carbon cementitious material 300~450 kg / m 3 ;

[0008] Solid waste-based lightweight aggregate 800~920 kg / m 3 ;

[0009] Solid waste-based artificial sand 300~550 kg / m 3 ;

[0010] Mineral admixture 0~100 kg / m 3 ;

[0011] Auxiliary materials 0~50 kg / m 3 ;

[0012] Water 110~160 kg / m 3 ;

[0013] It also includes a water reducer and a retarder, wherein the addition amount of the water reducer is 1.5-5wt% of the sulphur-aluminum-iron low-carbon cementitious material, and the addition amount of the retarder is 0.1-0.5wt% of the sulphur-aluminum-iron low-carbon cementitious material;

[0014] The solid waste-based lightweight aggregate and solid waste-based artificial sand are prepared from the following components in percentage by mass: 10-20% of sulfur-aluminum-iron low-carbon cementitious material, 0-90% of phosphogypsum or desulfurized gypsum, and 0-90% of fly ash or gold tailings.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned lightweight aggregate-based steam-free high-performance pipe culvert, comprising the following steps:

[0016] Pre-wetting the solid waste-based lightweight aggregate and the solid waste-based artificial sand with water respectively, so that the saturated surfaces of the solid waste-based lightweight aggregate and the solid waste-based artificial sand are dry;

[0017] Stir and mix the sulfur-aluminum-iron low-carbon cementitious materials, mineral admixtures and auxiliary materials, then add saturated surface-dried solid waste-based lightweight aggregate and solid waste-based artificial sand, water, retarder and water reducer, and pour into the culvert forming mold system after stirring to form the culvert. Let it stand naturally, demold within 4 hours, spray water, cover with plastic film and maintain for 1 to 3 days.

[0018] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0019] The lightweight aggregate-based steam-free high-performance pipe culvert provided by the present invention adopts sulfur-aluminum-iron low-carbon cementitious materials as the main cementitious materials, which have the characteristics of early strength, fast setting and high strength. At the same time, the raw materials for preparing both solid waste-based lightweight aggregate and solid waste-based artificial sand contain sulfur-aluminum-iron low-carbon cementitious materials. When preparing lightweight aggregate concrete pipe culvert, the hydration products of the cementitious materials are similar to the hydration products of lightweight aggregate and lightweight aggregate sand. Therefore, the hydration products of the cementitious materials can be embedded in the micropores in the lightweight aggregate. Therefore, the lightweight aggregate and lightweight aggregate sand are tightly bonded to the cementitious materials, the interface transition zone is dense, the overall strength is high, and the impermeability and durability are better. The proportion of solid waste in both solid waste-based lightweight aggregate and solid waste-based artificial sand can reach more than 80%. The lightweight aggregate-based steam-curing-free high-performance pipe culvert of the present invention has a compressive strength greater than 25 MPa within 4 hours after casting, and a compressive strength of more than 40 MPa at 28 days, and can utilize solid waste at a high proportion; during the preparation process of the pipe culvert, the construction performance is good, the demolding time is short, which is more than 75% shorter than the demolding time of conventional pipe culverts, no steam curing is required, the energy consumption is low, the product is shipped out quickly, and it has the remarkable characteristics of low production cost and high production efficiency. The crack load of the obtained pipe culvert is greater than 75 kN / m, the failure load is greater than 110 kN / m, and the internal water pressure is greater than 0.10 MPa. DETAILED DESCRIPTION

[0020] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0021] The present invention provides a lightweight aggregate-based, steam-free, high-performance pipe culvert, which is prepared from raw materials comprising the following components, measured by unit volume mass:

[0022] Sulfur-aluminum-iron low-carbon cementitious material 300~450 kg / m 3 ;

[0023] Solid waste-based lightweight aggregate 800~920 kg / m 3 ;

[0024] Solid waste-based artificial sand 300~550 kg / m 3 ;

[0025] Mineral admixture 0~100 kg / m 3 ;

[0026] Auxiliary materials 0~50 kg / m 3 ;

[0027] Water 110~160 kg / m 3 ;

[0028] It also includes a water reducer and a retarder, wherein the addition amount of the water reducer is 1.5-5wt% of the sulphur-aluminum-iron low-carbon cementitious material, and the addition amount of the retarder is 0.1-0.5wt% of the sulphur-aluminum-iron low-carbon cementitious material;

[0029] The solid waste-based lightweight aggregate and solid waste-based artificial sand are prepared from the following components in percentage by mass: 10-20% of sulfur-aluminum-iron low-carbon cementitious material, 0-90% of phosphogypsum or desulfurized gypsum, and 0-90% of fly ash or gold tailings.

[0030] The present invention uses sulfur-aluminum-iron low-carbon cementitious material as the main cementitious material of the culvert, which has the characteristics of early strength, fast setting and high strength. At the same time, the raw materials of the culvert of the present invention also include solid waste-based light aggregate and solid waste-based artificial sand, which also uses sulfur-aluminum-iron low-carbon cementitious material as cementitious material. Therefore, the hydration products of the cementitious material and aggregate in the culvert of the present invention have similar mineral phases, and the hydration products can be embedded in the micropores in the light aggregate. Therefore, the interface transition zone between the two is smooth, tightly combined, and has high strength. The 28-day compressive strength can reach more than 40MPa; the culvert is dense as a whole, and has strong resistance to sulfate dry-wet cycles and corrosion resistance. In addition, the proportion of solid wastes such as phosphogypsum in solid waste-based light aggregate and solid waste-based artificial sand is as high as more than 80%, which can greatly reduce costs and absorb a large amount of difficult-to-treat solid waste. Through the coordinated coordination of multiple components such as sulfur-aluminum-iron low-carbon cementitious materials, solid waste-based lightweight aggregates, solid waste-based artificial sand, etc., the culvert preparation process of the present invention has the characteristics of short demolding time, no need for steaming, low production cost, high production efficiency, etc. The obtained culvert has high strength and has very good application prospects.

[0031] In the present invention, the sulphur-aluminum-iron low-carbon cementitious material has CaO≥37%, Al2O3≥20%, Fe2O3≥6%, and SO3≥8%. The present invention does not impose any special restrictions on the preparation method of the sulphur-aluminum-iron low-carbon cementitious material, as long as it meets the standard "Sulphur-aluminum-iron low-carbon cementitious material" (T / CCPA 42-2023).

[0032] In the present invention, the bulk density of the solid waste-based lightweight aggregate is less than 1200 kg / m 3 , particle size is 5~20 mm, apparent density is 1600~1800 kg / m 3 , cylinder pressure strength is greater than 6 MPa, and softening coefficient is greater than 0.82. The solid waste-based lightweight aggregate of the present invention has the characteristics of light weight and high strength. Because of its high usage ratio, the total weight of the material can be effectively reduced.

[0033] In the solid waste-based lightweight aggregate of the present invention, the unit volume mass of the solid waste-based lightweight aggregate with a particle size of 5 to 10 mm is 240 to 280 kg / m 3 The unit volume mass of solid waste-based lightweight aggregate with a particle size of 10-20 mm is 560-640 kg / m 3.

[0034] In the present invention, the bulk density of the solid waste-based artificial sand is less than 1200 kg / m 3 The particle size is 0.15~4.75mm, the fineness modulus is 2.4~3.0, and the cylinder pressure strength is greater than 6MPa.

[0035] In the present invention, the preparation method of the solid waste-based lightweight aggregate is as follows: a sulfur-aluminum-iron series low-carbon cementitious material is mixed and stirred with phosphogypsum or desulfurized gypsum, fly ash or gold tailings, and then granulated, screened and shaped to obtain. The preparation method of the solid waste-based artificial sand is as follows: a sulfur-aluminum-iron series low-carbon cementitious material is mixed and stirred with phosphogypsum or desulfurized gypsum, fly ash or gold tailings, and then granulated and screened to obtain. The present invention does not impose special restrictions on the specific granulation, screening and shaping methods, and those skilled in the art can adjust the parameters according to the desired particle size.

[0036] In the present invention, the solid waste-based lightweight aggregate and solid waste-based artificial sand are more preferably made of the following components in percentage by mass: 10-20% of sulfide-aluminum-iron low-carbon cementitious material and 80-90% of phosphogypsum.

[0037] In the present invention, the mineral admixture is selected from one or both of fly ash and slag powder, wherein the quality grade of fly ash shall not be lower than Grade II fly ash, and the quality grade of slag powder shall not be lower than the relevant regulations of Grade S95. The mineral admixture can be used to replace part of the cementitious material.

[0038] In the present invention, the auxiliary material is selected from one or more of carbide slag, red mud or slaked lime, and the pH of the auxiliary material is ≥ 11. The auxiliary material functions to stimulate the gelling property of the mineral admixture.

[0039] In the present invention, the water reducing agent is a polycarboxylic acid-based high-performance water reducing agent with a water reduction rate of more than 25%.

[0040] In the present invention, the retarder is selected from boric acid or citric acid. The addition of the retarder can prolong the cement hydration time, making it easier to pour and construct.

[0041] The present invention also provides a method for preparing the above-mentioned lightweight aggregate-based steam-free high-performance pipe culvert, comprising the following steps:

[0042] Pre-wetting the solid waste-based lightweight aggregate and the solid waste-based artificial sand with water respectively, so that the saturated surfaces of the solid waste-based lightweight aggregate and the solid waste-based artificial sand are dry;

[0043] Stir and mix the sulfur-aluminum-iron low-carbon cementitious materials, mineral admixtures and auxiliary materials, and then add saturated surface-dry solid waste-based lightweight aggregate and solid waste-based artificial sand, water, retarder and water reducer. The amount of water added in this step is the design amount minus the amount of water used for pre-wetting in the previous step. After stirring, pour it into the culvert forming mold system for culvert forming, let it stand naturally, demould within 4 hours (after the compressive strength reaches 25MPa), spray water, cover with plastic film and maintain for 1 to 3 days.

[0044] The pipe culvert forming mold system of the present invention is composed of a lower hopper and a forming mold. The lower hopper is designed in a conical shape with a cone angle greater than 60 degrees. The inner wall of the forming mold is affixed with a PVC film to facilitate the demolding of the pipe culvert. The mold size depends on specific needs.

[0045] The present invention does not impose any special restrictions on the stirring process, and the stirring parameters commonly used in the art can be used.

[0046] By adopting the preparation method of the present invention, demoulding can be completed within 4 hours, the demoulding time is short, and the mold turnover is fast. At the same time, steam curing is not required after demoulding, energy consumption is saved, and production cost is low.

[0047] The lightweight aggregate-based steam-curing-free high-performance pipe culvert prepared by the preparation method of the present invention has a crack load of 75-150 kN / m; a failure load of 110-220 kN / m; an internal water pressure greater than 0.10 MPa; and meets the standard of GB / T 11836-2023 reinforced concrete pipe grade III pipe.

[0048] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0049] In the following embodiments, ferroaluminum-sulfur low-carbon cementitious materials meet the T / CCPA 42-2023 standard.

[0050] The solid waste-based artificial sand is made of 82wt% phosphogypsum and 18wt% sulfoaluminum-iron low-carbon cementitious material. The specific preparation method is as follows: adding phosphogypsum and sulfoaluminum-iron low-carbon cementitious material into a vertical mixer and stirring for 5 minutes to prepare a mixed powder; then o The mixed powder is added to the disc granulator, which rotates at 30Hz, spraying water and adding materials at the same time, and the powder becomes a masterbatch. Continue to rotate, add materials, and spray water to granulate until some particles are larger than 2.5mm. Then the material enters the screening machine with a jacket screen for screening, and the particles smaller than 0.15mm are returned to the disc granulator for further granulation; the finished solid waste-based artificial sand with a size of 0.15~4.75mm is screened out and enters the material box. It has been measured that the bulk density of solid waste-based artificial sand is 1100 kg / m 3 , fineness modulus is 2.4~3.0; cylinder pressure strength is greater than 6MPa.

[0051] The solid waste-based lightweight aggregate is prepared from 83wt% phosphogypsum and 17wt% sulfoaluminum-iron low-carbon cementitious material. The specific preparation method is as follows: adding phosphogypsum and sulfoaluminum-iron low-carbon cementitious material into a vertical mixer and stirring for 5 minutes to prepare a mixed powder; then o Mixed powder is added to the disc granulator, which rotates at 30Hz, spraying water and adding materials at the same time, and the powder becomes masterbatch. Continue to add materials, spray water, and granulate until some particles are larger than 10mm, and then the materials enter the screening machine with a jacket screen for screening; particles smaller than 5mm are returned to the disc granulator for further granulation. The sieved particles of 5~10mm and 10~20mm are placed at an inclination angle of 50 o The disc shaping machine rotates and shapes the aggregate to sphericity for 5 minutes and 3 minutes respectively, and the strength meets the requirements. The finished solid waste-based lightweight aggregate enters the material box. It has been measured that the bulk density of the obtained solid waste-based lightweight aggregate is less than 1080kg / m 3 , the apparent density is 1680kg / m 3 , cylinder pressure strength is greater than 8MPa, and the softening coefficient is 0.83.

[0052] The pipe culvert forming mold system in the following embodiments consists of a lower hopper and a forming mold. The lower hopper is conical in design with a cone angle greater than 60 degrees. The inner wall of the forming mold is affixed with a PVC film.

[0053] Example 1

[0054] The present embodiment provides a lightweight aggregate-based, steam-curing-free, high-performance pipe culvert and a preparation method thereof.

[0055] The lightweight aggregate-based steam-free high-performance pipe culvert of this embodiment is prepared from raw materials including the following components, based on unit volume mass: the amount of solid waste-based lightweight aggregate is 850 kg / m 3 (The dosage for particles with a diameter of 5 to 10 mm is 255 kg / m 3 , the dosage for particle size of 10~20 mm is 595 kg / m 3 ); the amount of solid waste-based artificial sand is 500 kg / m 3 The dosage of ferroaluminum-sulfur low-carbon cementitious material is 450 kg / m 3 The total water consumption is 130 kg / m 3 ; The amount of retarder (boric acid) added is 0.9 kg / m 3 ; The addition amount of polycarboxylic acid high performance water reducer is 20.25 kg / m 3 .

[0056] The preparation method is as follows:

[0057] Step 1: Pre-wet the solid waste-based lightweight aggregate and solid waste-based artificial sand with water respectively, soak them for 1 hour, and make them saturated and dry.

[0058] Step 2: Add saturated surface-dry solid waste-based lightweight aggregate and solid waste-based artificial sand to the sulfide-aluminum-iron low-carbon cementitious material, then add the remaining water, retarder and polycarboxylic acid-based high-performance water reducing agent, stir for 1.5 minutes, and obtain lightweight aggregate concrete.

[0059] Step 3: Pour the lightweight aggregate concrete obtained in step 2 into the culvert forming mold system, vibrate the mold mechanically for 10 minutes, and let it stand at room temperature (25±3°C).

[0060] Step 4: After 3 hours, the strength of the culvert is greater than 25 MPa and the culvert is demoulded; the inner diameter of the culvert is 1500 mm, the wall thickness is 150 mm, and the length is 2000 mm.

[0061] Step 5: Pipe culvert maintenance: spray water at room temperature (25±3℃), cover with plastic film and maintain for 2 days.

[0062] Example 2

[0063] The present embodiment provides a lightweight aggregate-based, steam-curing-free, high-performance pipe culvert and a preparation method thereof.

[0064] The steam-free high-performance pipe culvert of this embodiment is prepared from raw materials including the following components, based on unit volume mass: the amount of solid waste-based lightweight aggregate is 870 kg / m 3 (The dosage for particles with a diameter of 5 to 10 mm is 255 kg / m 3 , the dosage for particles with a diameter of 10-20 mm is 615 kg / m 3 ); the amount of solid waste-based artificial sand is 480 kg / m 3 The dosage of ferro-aluminum low-carbon cementitious material is 400kg / m 3 , carbide slag 18 kg / m 3 , slag powder 32 kg / m 3 The total water consumption is 122 kg / m 3 ; The amount of retarder (boric acid) added is 0.8kg; The amount of polycarboxylic acid high-performance water reducer added is 18kg.

[0065] The preparation method is as follows:

[0066] Step 1: Pre-wet the solid waste-based lightweight aggregate and solid waste-based artificial sand with water respectively, soak them for 1 hour, and make them saturated and dry.

[0067] Step 2: Mix the sulfide-aluminum-iron low-carbon cementitious material, carbide slag and slag powder for 0.5 minutes, then add saturated surface-dried solid waste-based lightweight aggregate and solid waste-based artificial sand, and then add the remaining water, retarder and polycarboxylic acid-based high-performance water reducer, stir for 1.5 minutes to obtain lightweight aggregate concrete.

[0068] Step 3: Pour the lightweight aggregate concrete from step 2 into the culvert forming mold system, vibrate the mold mechanically for 15 minutes, and let it stand at room temperature (25±3°C).

[0069] Step 4: After 3.3 hours, the strength of the culvert is greater than 25 MPa and the culvert is demoulded; the inner diameter of the culvert is 1200 mm, the wall thickness is 120 mm, and the length is 2000 mm.

[0070] Step 5: Pipe culvert maintenance: spray water at room temperature (25±3℃), cover with plastic film and maintain for 2 days.

[0071] Example 3

[0072] The present embodiment provides a lightweight aggregate-based, steam-curing-free, high-performance pipe culvert and a preparation method thereof.

[0073] The steam-free high-performance pipe culvert of this embodiment is prepared from raw materials including the following components, based on unit volume mass: the amount of solid waste-based lightweight aggregate is 920 kg / m 3 (The dosage for particles with a diameter of 5 to 10 mm is 255 kg / m 3 , the dosage for particles with a diameter of 10-20 mm is 615 kg / m 3 ); the amount of solid waste-based artificial sand is 400 kg / m 3 The dosage of sulfide-aluminum-iron low-carbon cementitious material is 450kg / m 3 The total water consumption is 148 kg / m 3 ; The amount of retarder (boric acid) added is 0.9 kg / m 3 ; The addition amount of polycarboxylic acid high performance water reducer is 20.25 kg / m 3 .

[0074] The preparation method is as follows:

[0075] Step 1: Pre-wet the solid waste-based lightweight aggregate and solid waste-based artificial sand with water, soak them for 1 hour, and then make them saturated and dry.

[0076] Step 2: Add saturated surface-dry solid waste-based lightweight aggregate and solid waste-based artificial sand to the sulfide-aluminum-iron low-carbon cementitious material, then add the remaining water, retarder and polycarboxylic acid-based high-performance water reducing agent, stir for 1.5 minutes, and obtain lightweight aggregate concrete.

[0077] Step 3: Pour the lightweight aggregate concrete from step 2 into the culvert forming mold system, mechanically vibrate for 10 minutes, and let it stand at room temperature (25±3°C).

[0078] Step 4: After 3.5 hours, the strength of the culvert is greater than 25 MPa and the culvert is demoulded; the inner diameter of the culvert is 800 mm, the wall thickness is 80 mm, and the length is 1500 mm.

[0079] Step 5: Pipe culvert maintenance: spray water at room temperature (25±3℃), cover with plastic film and maintain for 3 days.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing an ordinary Portland cement-based pipe culvert.

[0082] The ordinary Portland cement-based pipe culvert of this comparative example is prepared from the following raw materials based on unit volume mass: the amount of gravel (GB175-2023) is 1175 kg / m 3 ; The amount of machine-made sand (GB175-2023) is 720 kg / m 3 PO 42.5 ordinary Portland cement (GB175-2023) dosage is 400 kg / m 3 The total water consumption is 138 kg / m 3 The dosage of polycarboxylic acid high performance water reducer is 18 kg / m 3 .

[0083] The preparation method is as follows:

[0084] Step 1: Pour silicate cement, gravel and machine-made sand into a mixer, stir for 0.5 minutes, then add water and polycarboxylic acid-based high-performance water reducer, stir for 1.5 minutes to obtain ordinary concrete.

[0085] Step 2: Pour the ordinary concrete prepared in step 1 into the pipe culvert forming mold system, mechanically vibrate for 18 minutes, and let it stand at room temperature (25±3°C).

[0086] Step 3: After 24 hours, the strength of the culvert is greater than 31 MPa and the culvert is demoulded; the inner diameter of the culvert is 1200 mm, the wall thickness is 120 mm, and the length is 2000 mm.

[0087] Step 4: Pipe culvert maintenance: Steam curing for 1 day, then natural curing for 26 days.

[0088] Comparative Example 2

[0089] This comparative example provides a method for preparing an ordinary Portland cement-based pipe culvert.

[0090] The ordinary Portland cement-based pipe culvert of this comparative example is prepared from the following raw materials based on unit volume mass: the amount of stone is 1195 kg / m 3 ; The amount of machine-made sand is 700 kg / m 3 , the amount of silicate cement is 400 kg / m 3 The total water consumption is 130 kg / m 3The dosage of polycarboxylic acid high performance water reducer is 18 kg / m 3 .

[0091] The preparation method is as follows:

[0092] Step 1: Pour silicate cement, gravel and machine-made sand into a mixer, stir for 0.5 minutes, then add water and polycarboxylic acid-based high-performance water reducer, stir for 1.5 minutes to obtain ordinary concrete.

[0093] Step 2: Pour the ordinary concrete prepared in step 1 into the pipe culvert forming mold system, mechanically vibrate for 18 minutes, and let it stand at room temperature (25±3°C).

[0094] Step 3: After 24 hours, the strength of the culvert is greater than 31 MPa and the culvert is demoulded; the inner diameter of the culvert is 1200 mm, the wall thickness is 120 mm, and the length is 2000 mm.

[0095] Step 4: Pipe culvert maintenance: Steam curing for 1 day, then natural curing for 26 days.

[0096] Test example

[0097] The performance data of the lightweight aggregate concrete of Examples 1 to 3 and the ordinary concrete of Comparative Examples 1 to 2 are shown in Table 1.

[0098] Table 1 Concrete performance data of Examples 1 to 3 and Comparative Examples 1 to 2

[0099]

[0100] From the data in Table 1, it can be seen that the fluidity and slump indexes of the lightweight aggregate concrete of Examples 1 to 3 are better than the fluidity and slump of the ordinary concrete of Comparative Examples 1 to 2, indicating that it has better construction performance.

[0101] The performance data of the pipe culverts of Examples 1-3 and Comparative Examples 1-2 are shown in Table 2.

[0102] Table 2 Performance data of pipe culverts of Examples 1 to 3 and Comparative Examples 1 to 2

[0103]

[0104] From the data in Table 2, it can be seen that the pipe culverts of Examples 1 to 3 can reach a compressive strength of more than 30 MPa within 4 hours. The ordinary Portland cement-based pipe culvert needs steam curing after demoulding, and steam heating is used to accelerate the hardening process of Portland cement-based concrete; while the lightweight aggregate concrete pipe culverts of Examples 1 to 3 of the present invention do not need steam curing after demoulding, and all parameters can meet the use requirements, and Examples 1 to 3 can meet the standards of GB / T 11836-2023 reinforced concrete pipes, Grade III pipes. In addition, it has been determined that the pipe culverts of Examples 1 to 3 of the present invention have a sulfate dry-wet cycle resistance of more than 50 times, and have good corrosion resistance and durability.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lightweight aggregate-based, steam-free, high-performance pipe culvert, characterized in that: Measured by unit volume mass, it is prepared from raw materials containing the following components: Sulfur-aluminum-iron low-carbon cementitious material 300~450 kg / m 3 ; Solid waste-based lightweight aggregate 800~920 kg / m 3 ; Solid waste-based artificial sand 300~550 kg / m 3 ; Mineral admixture 0~100 kg / m 3 ; Auxiliary materials 0~50 kg / m 3 ; Water 110~160 kg / m 3 ; It also includes a water reducer and a retarder, wherein the addition amount of the water reducer is 1.5-5wt% of the sulphur-aluminum-iron low-carbon cementitious material, and the addition amount of the retarder is 0.1-0.5wt% of the sulphur-aluminum-iron low-carbon cementitious material; The solid waste-based lightweight aggregate and solid waste-based artificial sand are prepared from the following components in percentage by mass: 10-20% of sulfur-aluminum-iron low-carbon cementitious material, 0-90% of phosphogypsum or desulfurized gypsum, and 0-90% of fly ash or gold tailings.

2. The lightweight aggregate-based, steam-curing-free, high-performance pipe culvert according to claim 1, characterized in that: In the sulphur-aluminum-iron low-carbon cementitious material, CaO≥37%, Al2O3≥20%, Fe2O3≥6%, and SO3≥8%.

3. The lightweight aggregate-based, steam-curing-free, high-performance pipe culvert according to claim 1, characterized in that: The bulk density of the solid waste-based lightweight aggregate is less than 1200 kg / m 3 , particle size is 5~20 mm, apparent density is 1600~1800 kg / m 3 , cylinder pressure strength is greater than 6MPa, and softening coefficient is greater than 0.

82.

4. The lightweight aggregate-based, steam-curing-free, high-performance pipe culvert according to claim 1, characterized in that: The unit volume mass of the solid waste-based light aggregate with a particle size of 5 to 10 mm is 240 to 280 kg / m 3 The unit volume mass of solid waste-based lightweight aggregate with a particle size of 10-20 mm is 560-640 kg / m 3 .

5. The lightweight aggregate-based, steam-curing-free, high-performance pipe culvert according to claim 1, characterized in that: The bulk density of the solid waste-based artificial sand is less than 1200 kg / m 3 , particle size is 0.15~4.75mm, fineness modulus is 2.4~3.0, and cylinder pressure strength is greater than 6 MPa.

6. The lightweight aggregate-based, steam-curing-free, high-performance pipe culvert according to claim 1, characterized in that: The mineral admixture is selected from one or both of fly ash and slag powder; the auxiliary material is selected from one or more of carbide slag, red mud or slaked lime, and the pH of the auxiliary material is ≥11.

7. The lightweight aggregate-based, steam-curing-free, high-performance pipe culvert according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid-based high-performance water reducing agent with a water reduction rate of more than 25%.

8. The lightweight aggregate-based, steam-curing-free, high-performance pipe culvert according to claim 1, characterized in that: The retarder is selected from boric acid or citric acid.

9. The method for preparing a lightweight aggregate-based, steam-curing-free high-performance pipe culvert according to any one of claims 1 to 8, characterized in that: The steps include: Pre-wetting the solid waste-based lightweight aggregate and the solid waste-based artificial sand with water respectively, so that the saturated surfaces of the solid waste-based lightweight aggregate and the solid waste-based artificial sand are dry; Stir and mix the sulfur-aluminum-iron low-carbon cementitious materials, mineral admixtures and auxiliary materials, then add saturated surface-dried solid waste-based lightweight aggregate and solid waste-based artificial sand, water, retarder and water reducer, and pour into the culvert forming mold system after stirring to form the culvert. Let it stand naturally, demold within 4 hours, spray water, cover with plastic film and maintain for 1 to 3 days.

10. The preparation method according to claim 9, characterized in that: The pipe culvert forming mold system consists of a lower hopper and a forming mold. The lower hopper is conical in design with a cone angle greater than 60 degrees. The inner wall of the forming mold is affixed with a PVC film.

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