Construction method of foam lightweight concrete suitable for long-distance pipeline transportation

Abstract

The invention relates to the field of building material construction, and discloses a construction method of foam lightweight concrete suitable for long-distance pipeline transportation, and the construction method comprises the following steps: selecting a high-pressure hose with the pipe diameter of DN 100mm-DN 150mm as a pumping pipeline; before the foam lightweight concrete is conveyed, a hydroxypropyl methyl cellulose aqueous solution with the mass concentration of 0.05%-0.15% is used for pre-wetting the pumping pipeline, and a lubricating layer is formed on the inner wall of the pumping pipeline; and the foam lightweight concrete is conveyed to a construction area through the pumping pipeline to be poured. According to the method, through construction process improvement (pipeline lubrication and buffer pouring), the foam light soil can be transported for a long distance (larger than or equal to 500 m).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of construction materials construction, and mainly relates to a construction method of foam lightweight concrete suitable for long-distance pipeline transportation. BACKGROUND

[0002] As a new type of building material, foam lightweight concrete has unique application value in the field of construction. It has the characteristics of light weight, heat preservation, sound insulation, etc., can effectively reduce the self-weight of the building, reduce the foundation load, and perform well in heat preservation and insulation, which helps to improve the energy utilization efficiency of the building. In some large-span buildings, roof insulation and filling engineering, foam lightweight concrete has been widely used.

[0003] However, the traditional foam lightweight concrete technology has many defects. In engineering application, its construction performance is poor, and it is difficult to realize long-distance pipeline transportation, which limits its application in some large projects.

[0004] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] In view of the shortcomings of the prior art, the purpose of the present application is to provide a construction method of foam lightweight concrete suitable for long-distance pipeline transportation, which aims to solve the problem of deterioration of material performance of existing foam lightweight concrete in long-distance pipeline transportation (≥500 meters).

[0006] The technical scheme of the present application is as follows: A construction method of foam lightweight concrete suitable for long-distance pipeline transportation, comprising the following steps: Selecting a high-pressure hose with a pipe diameter of DN100mm-DN150mm as a pumping pipeline; Before transporting the foam lightweight concrete, a hydroxypropyl methyl cellulose aqueous solution with a mass concentration of 0.05%-0.15% is used to pre-wet the pumping pipeline, forming a lubricating layer on the inner wall of the pumping pipeline; The foam lightweight concrete is transported to the construction area through the pumping pipeline for pouring.

[0007] The present application improves the construction process (pipeline lubrication, buffer pouring) so that foam lightweight soil can be transported for a long distance (≥500 meters).

[0008] The construction method of foam lightweight concrete suitable for long-distance pipeline transportation, wherein the process of pre-wetting the pumping pipeline with a hydroxypropyl methyl cellulose aqueous solution with a mass concentration of 0.05%-0.15% specifically comprises the following steps: The inner wall of the pumping pipe is first rinsed with tap water and then dried with compressed air; Dissolve HPMC in hot water at 50-70℃ to prepare a 0.05%-0.15% mass concentration HPMC aqueous solution, and naturally cool to 25±2℃; First, fill the pumping pipe with the HPMC aqueous solution, and then circulate the HPMC aqueous solution in the pumping pipe for 2-4 minutes; Drain the residual liquid and naturally dry for 30-45 minutes to form a dense lubricating layer.

[0009] In this application, the pre-wetting process is an important measure to improve the stability of pipeline transportation. Before each operation, the pipeline is pre-wetted with a 0.05-0.15% mass concentration hydroxypropyl methylcellulose aqueous solution to form a lubricating layer, reducing the friction between the concrete and the inner wall of the pipeline.

[0010] The construction method of the foamed lightweight concrete suitable for long-distance pipeline transportation, wherein when the foamed lightweight concrete is transported through the pumping pipe to the construction area, a hydraulic piston pump is used to transport the foamed lightweight concrete, the pumping pressure is 10-15 MPa, and the control flow rate is 1.5-2.0 m / s.

[0011] The construction method of the foamed lightweight concrete suitable for long-distance pipeline transportation, wherein the pipe diameter of the pumping pipe is DN150 mm.

[0012] The construction method of the foamed lightweight concrete suitable for long-distance pipeline transportation, wherein the pouring process specifically includes the following steps: (1) According to the height, width and length of the pouring body, the pouring body is divided into segments, layers and blocks to form a plurality of pouring blocks, and a formwork is set up for the pouring body that has been segmented, layered and blocked; (2) Pouring: after completing the pouring of a layer of the pouring block, the pouring of the upper layer of the pouring block is carried out after the layer of the pouring block is fully cured, until the design elevation is reached; (3) Cover the surface of the pouring body with a moisture-retaining felt, and set up a humidity sensor to monitor the humidity in real time, automatically spray a curing agent to make the humidity of the moisture-retaining felt ≥90%, keep the surface of the pouring body wet, and the curing time is set to 7 days.

[0013] The construction method of the foamed lightweight concrete suitable for long-distance pipeline transportation, wherein in this step (2), the height of each pouring block is controlled to be 250-300 mm, the pouring time interval between layers is controlled to be within 45 minutes in summer, and the pouring time interval between layers is controlled to be within 90 minutes in winter.

[0014] The construction method of the foamed lightweight concrete suitable for long-distance pipeline transportation, wherein the process of segmenting, layering and blocking the pouring body into several pouring blocks comprises the following steps: Segmenting the pouring body according to functional areas to divide it into several segment construction sections; Layering each segment construction section according to height to divide it into several layer pouring layers, and the height of each layer pouring layer is controlled to be between 250-300 mm; Blocking each layer pouring layer according to cement pumping flow rate and cement paste initial setting time to divide it into several block pouring blocks.

[0015] The construction method of the foamed lightweight concrete suitable for long-distance pipeline transportation, wherein before step (2), the following steps are further included: Embedding galvanized steel wire mesh; The pore size of the galvanized steel wire mesh is 50-150 mm x 50-150 mm.

[0016] The construction method of the foamed lightweight concrete suitable for long-distance pipeline transportation, wherein the galvanized steel wire mesh is arranged at a position 0.5 m-1 m below the top surface of the pouring body, and a layer of the galvanized steel wire mesh is further arranged every 500-600 mm in thickness.

[0017] The construction method of the foamed lightweight concrete suitable for long-distance pipeline transportation, wherein the foamed lightweight concrete comprises slurry and foam group; The volume ratio of the foam group to the slurry is 1.67-2.5:1; The slurry comprises the following raw materials according to mass fraction: Cement 30-50 parts, fly ash 10-25 parts, hydroxypropyl methylcellulose 0.02-0.04 parts, water reducing agent 0.08-0.2 parts, and first water 25-40 parts; The foam group is prepared from a nano-stable foaming agent composition and second water; The mass ratio of the nano-stable foaming agent composition to the second water is 1:300-350; The nano-stable foaming agent composition comprises the following according to mass fraction: Polyacrylamide 0.5-5 parts, polyethyleneimine 3-20 parts, polyvinylpyrrolidone 10-20 parts, hydroxypropyl methylcellulose 35-50 parts, triethanolamine 1-5 parts, surface hydrophilic modified nano titanium oxide 20-35 parts, and surfactant 15-30 parts.

[0018] Beneficial effects: The application can realize long-distance (≥500 meters) transportation of foam lightweight soil through construction process improvement (pipeline lubrication, buffer pouring). BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The structure diagram of the application is provided in the pouring body. DETAILED DESCRIPTION

[0020] The application provides a construction method of foam lightweight concrete suitable for long-distance pipeline transportation. In order to make the purpose, technical scheme and effect of the application more clear and explicit, the application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0021] In the application, a construction method of foam lightweight concrete suitable for long-distance pipeline transportation is provided, which includes the following steps: A1, selecting a high-pressure hose with a pipe diameter of DN100mm-DN150mm as a pumping pipeline; A2, before transporting the foam lightweight concrete, first pre-wetting the pumping pipeline with a hydroxypropyl methyl cellulose aqueous solution with a mass concentration of 0.05%-0.15% to form a lubricating layer on the inner wall of the pumping pipeline, thereby reducing the friction between the foam lightweight concrete and the inner wall of the pipeline; A3, transporting the foam lightweight concrete to the construction area for pouring; when transporting the foam lightweight concrete, a hydraulic piston pump is used to transport the foam lightweight concrete, the pumping pressure is adjusted to 10-15MPa, and the flow rate is controlled to be 1.5-2.0 m / s.

[0022] In the application, the pre-wetting process is an important measure to improve the stability of pipeline transportation. Before each operation, the pipeline is pre-wetted with a hydroxypropyl methyl cellulose aqueous solution with a mass concentration of 0.05-0.15% to form a lubricating layer, thereby reducing the friction between the concrete and the inner wall of the pipeline. The viscosity and pipeline lubricity of the hydroxypropyl methyl cellulose aqueous solution with this mass concentration range are good. The hydroxypropyl methyl cellulose used for pre-wetting is the same as that used for the slurry.

[0023] Specifically, the HPMC aqueous solution pipeline pre-wetting process specifically includes the following steps: (1) pipeline pretreatment: first rinse the inner wall of the pipeline with tap water, and then blow dry with compressed air to remove oil stains and particles; (2) solution preparation: dissolve HPMC in hot water at 50-70℃ to prepare an HPMC aqueous solution with a mass concentration of 0.05%-0.15%, and naturally cool to 25±2℃; (3) Circulating coating: firstly fill the pump pipeline with HPMC aqueous solution, and then circulate the HPMC aqueous solution in the pump pipeline for 2-4 minutes to ensure uniform wetting; (4) Drying and film forming: discharge the residual liquid and naturally dry for 30-45 minutes to form a dense lubricating layer.

[0024] The specific operation of step (3) can be that the HPMC aqueous solution is loaded into a storage barrel, the pipeline inlet of the pump pipeline is connected with the discharge port of the storage barrel, then the pipeline outlet of the pump pipeline is placed in the storage barrel containing the HPMC aqueous solution, the pump pipeline is filled with the HPMC aqueous solution by pumping, and then the HPMC aqueous solution is circulated in the pump pipeline by continuous pumping to uniformly wet the pump pipeline.

[0025] At the same time, the pumping parameters are optimized, such as controlling the pumping speed and pressure (controlling the flow rate of 1.5-2.0 m / s, pump pressure of 10-15 MPa, so that the conveying distance can reach 500 meters (the limit of traditional process is 300 meters), which can effectively improve the bubble survival rate and pumping efficiency. The pipe diameter selection and pressure regulation of the pump pipeline also have important engineering logic. If the pipe diameter is too small, it is easy to cause pipeline blockage, and if the pipe diameter is too large, it will reduce the pumping efficiency. According to the test results, the pipe diameter of DN100mm-DN150mm is more appropriate, and the preferred one is DN150mm. In terms of pressure regulation, the pumping pressure is reasonably adjusted according to the conveying distance and height to ensure that the foam lightweight concrete can be smoothly conveyed.

[0026] In the prior art, the distance of generally maintaining stable pipe conveying of foam lightweight concrete is generally within 300m, and the traditional process can also achieve long-distance pipe conveying of 500m. However, when the distance exceeds 300m, the foam lightweight concrete will have a low bubble survival rate and a large amount of bubble breakage due to large pumping pressure, large roughness resistance along the pipeline, and ordinary foam agent, which will cause the end of the discharge to have a sharp increase in bulk density, resulting in unstable pipe conveying and unreliable and unstable quality. Through effect data verification, in the scheme of the present application, the above pre-wetting process and optimized pumping parameters are adopted, and after 500m pipeline conveying, the bubble survival rate is ≥90% (the traditional material is only 70%-80%). At the same time, the inner wall of the pipeline is pre-coated with 0.1% HPMC solution, which can form a hydrophilic lubricating layer with a thickness of about 20-30μm. Compared with the same density of traditional materials, the pumping pressure can be reduced by 20%-30%, there is no pipe blockage phenomenon after 2 hours of continuous conveying, the construction efficiency is improved by 40%, the lubricating layer can maintain effectiveness for 4 hours, which meets the intermittent construction demand, and effectively solves the problem of long-distance pipeline conveying.

[0027] In step A3, the foam lightweight concrete used is the foam lightweight concrete suitable for long-distance pipeline conveying described above, and the wet density is 640-830kg / m 3 , and the dry density is 480-620kg / m3 .

[0028] In the present application, a preferred formula of the foamed lightweight concrete suitable for long-distance transportation is also provided, which comprises a slurry and a foam group; The volume ratio of the foam group to the slurry is 1.67-2.5:1. The slurry comprises the following raw materials in parts by mass: Cement 30-50 parts, fly ash 10-25 parts, hydroxypropyl methyl cellulose 0.02-0.04 parts, water reducing agent 0.08-0.2 parts, and first water 25-40 parts; The foam group is prepared from a nano-stabilized foaming agent composition and second water. The mass ratio of the nano-stabilized foaming agent composition to the second water is 1:300-350. The nano-stabilized foaming agent composition comprises the following components in parts by mass: Polyacrylamide 0.5-5 parts, polyethylene imine 3-20 parts, polyvinylpyrrolidone 10-20 parts, hydroxypropyl methyl cellulose 35-50 parts, triethanolamine 1-5 parts, surface hydrophilic modified nano-titanium oxide 20-35 parts, and surfactant 15-30 parts.

[0029] Preferably, the nano-stabilized foaming agent composition comprises polyacrylamide 0.8-3 parts, polyethylene imine 4-15 parts, polyvinylpyrrolidone 12-18 parts, hydroxypropyl methyl cellulose 36-45 parts, triethanolamine 2-4 parts, surface hydrophilic modified nano-titanium oxide 22-30 parts, and surfactant 16-25 parts in parts by mass.

[0030] The surface hydrophilic modified nano-titanium oxide is obtained by surface hydrophilic modification of nano-titanium oxide using at least one of alkoxylated alkyl glycol, alkoxylated alkyl acetylenic diol, and siloxane copolyol (the specific modification process is a conventional process in the art).

[0031] The surfactant is selected from at least one of alkoxylated alkyl glycol, alkoxylated alkyl acetylenic diol, and siloxane copolyol.

[0032] The nano-stabilized foaming agent composition is prepared by directly mixing the components.

[0033] Further, the cement is Portland cement, and more further, P·II 52.5R Portland cement is used.

[0034] The fly ash is first-grade fly ash. In the present application, the amount of fly ash is 10-25 parts, and the utilization rate of fly ash solid waste is ≥25%.

[0035] In the raw materials of the slurry, the apparent viscosity of hydroxypropyl methylcellulose (HPMC) is 100,000-200,000 mPa·s. In the scheme of this application, the amount of hydroxypropyl methylcellulose in the slurry is 0.02-0.04 parts. The main functions of HPMC in the slurry are water retention to delay water loss, appropriate thickening effect to ensure uniform foam distribution, and enhanced foam stability to prevent bubble collapse during pipeline transportation and casting.

[0036] In the raw materials of the slurry, the water-reducing agent is a polycarboxylate superplasticizer with a solid content of 50.0±1%. In this application, the dosage of the polycarboxylate superplasticizer is 0.08-0.2 parts. The polycarboxylate superplasticizer is used to improve the fluidity of lightweight foamed concrete and enhance its early strength.

[0037] Furthermore, the density of the foam cluster is less than 50 kg / m³. 3 Excessive foam density can directly lead to insufficient fluidity of foamed lightweight concrete slurry, thus affecting construction performance and reducing the mechanical properties of the product.

[0038] In this application, a composite nano-modified stabilizing foaming agent is used. The foam group produced by the foaming machine has the advantages of low density, high stability, and uniform and closed foam pores. The foamed lightweight concrete prepared using this foam group has the characteristics of higher strength at the same dry density level and lower dry density at the same strength level.

[0039] Furthermore, the foamed lightweight concrete of this application, suitable for long-distance pipeline transportation, has a wet density of 640-830 kg / m³. 3 Dry density is 480-620 kg / m³ 3 .

[0040] This application also provides a method for preparing this foamed lightweight concrete suitable for long-distance pipeline transportation, comprising the following steps: S1. Cement, fly ash and hydroxypropyl methylcellulose are mixed evenly to obtain dry powder material.

[0041] Specifically, cement, fly ash, and hydroxypropyl methylcellulose can be mixed evenly in the mixer of an integrated machine for 1-2 minutes to obtain a dry powder material.

[0042] S2. Mix the nano-stabilized foaming agent composition with the second water to obtain a foaming agent solution; after letting the foaming agent solution stand for 30-40 minutes, prepare foam clusters using a foaming machine and weigh their density, which should be below 50 kg / m³. 3 The standard is ready for use.

[0043] In step S2, the temperature of the second water is preferably 20-40°C. Too high a water temperature will cause the generated foam to defoam, and too low a water temperature will cause the nano-stabilized foaming agent composition to fail to dissolve completely in the water.

[0044] Furthermore, this foamed lightweight concrete is prepared and pumped using the NJFZY-50 foamed lightweight concrete foaming, mixing, and pumping integrated machine from Shandong Naijiu Industrial Equipment Co., Ltd. The foam produced by the foaming machine of this equipment has the characteristics of lower density, greater uniformity, and stability.

[0045] S3. After mixing the polycarboxylate superplasticizer and the first water evenly, add it to the dry powder material obtained in step S1 and mix evenly to obtain a slurry; mix the foam group obtained in S2 with the slurry to obtain the foamed lightweight concrete suitable for long-distance pipeline transportation of this application.

[0046] Specifically, the first water can be added to the dry powder material obtained in step S1 and mixed evenly for 2-3 minutes to obtain a slurry; then, the foam group obtained in S2 is rapidly stirred and mixed with the slurry in the spiked feeding pipe of the above equipment, and foamed lightweight concrete suitable for long-distance pipeline transportation can be obtained at the outlet of the spiked feeding pipe.

[0047] Furthermore, the pouring process in step A3 specifically includes the following steps: (1) According to the height, width and length of the casting body, the casting body is divided into several casting blocks by segmenting, layering and blocking, and templates are set up for the casting body that has been segmented, layered and blocked.

[0048] This application employs a segmented and layered pouring process, which is crucial in the construction of foamed lightweight concrete. Formwork setup is the first step; high-strength, well-sealed formwork must be used according to the engineering design requirements to ensure no leakage occurs during the pouring of the foamed lightweight concrete. The formwork joints must be tight, and the supports must be firm to withstand the lateral pressure of the foamed lightweight concrete.

[0049] Furthermore, depending on the specific working conditions, after establishing the template, the following steps may also be included: A protective wall is installed on the open side of the casting body; After the protective wall is installed, it is also necessary to check the planar position, top height, node connection, longitudinal and transverse stability, and tightness of the joints.

[0050] After the foamed lightweight concrete is poured according to the replacement thickness, ordinary soil can be used for backfilling on the sides and top of the foamed lightweight concrete. The entire backfilling construction can be carried out by vertical filling.

[0051] In this scheme, the process of dividing the cast-in-place body into several casting blocks by segmentation, layering, and slabming includes the following steps: The cast-in-place structure (i.e., building structure) is divided into several construction sections according to functional areas; Then, each construction section is further divided into several layers according to its height, with the height (i.e. thickness) of each layer controlled between 250-300mm. Finally, each layer of concrete is further divided into several pouring blocks based on the cement pumping flow rate and the initial setting time of the cement slurry.

[0052] (2) Pouring: After the first layer of the pouring block is completed, the next layer of the pouring block is poured after the first layer of the pouring block has set, until the design elevation is reached. When pouring each pouring block, the construction time of each pouring block is controlled within the initial setting time of the cement slurry.

[0053] In this step (2), the thickness of each pouring block (i.e., the height of each pouring layer) is controlled at 250-300mm. During the summer operation period, the time interval between pouring layers is controlled within 45 minutes, and during the winter operation period, the time interval between pouring layers is controlled within 90 minutes. This ensures the compactness of the foamed lightweight concrete and avoids difficulties in air bubble discharge due to excessive thickness in one pour. After each pouring block is completed, appropriate vibration is required to promote the integrity of the filling, but excessive vibration should be avoided to prevent damage to the air bubble structure.

[0054] To enhance the integrity and crack resistance of concrete, galvanized steel wire mesh is embedded in the pouring area near the layer interface, significantly improving the crack resistance coefficient. As a vertical reinforcing framework, the galvanized steel wire mesh forms a composite structure with the foamed lightweight concrete, effectively improving overall impact resistance and reducing the risk of cracking due to material shrinkage or external forces. Simultaneously, the mesh connection of the galvanized steel wire mesh enhances structural continuity, significantly improving seismic performance and ensuring the long-term stability and durability of the poured concrete. The mesh size of the galvanized steel wire mesh can be 50-150 mm × 50-150 mm, preferably 100 mm × 100 mm, achieving both enhanced structural stability and crack resistance while reducing costs.

[0055] Therefore, before proceeding to step (2), the following steps are also included: Pre-embedded galvanized steel wire mesh.

[0056] Specifically, such as Figure 1As shown, the galvanized steel wire mesh is positioned 0.5m-1m below the top surface of the entire cast-in-place structure, and an additional layer of galvanized steel wire mesh is installed every 500-600mm of thickness. The spacing of the galvanized steel wire mesh is set to twice the thickness of the cast-in-place layer. Given the thickness of the cast-in-place structure, the location of each layer of galvanized steel wire mesh is calculated based on the thickness. When pouring the sections requiring galvanized steel wire mesh, the mesh is pre-embedded before pouring. Figure 1 Taking the cast-in-place structure as an example, the cast-in-place structure is divided into 5 layers according to its height. From bottom to top, they are the first layer 1, the second layer 2, the third layer 3, the fourth layer 4, and the fifth layer 5. The top surface of the entire cast-in-place structure is the top surface of the fifth layer 5. The first galvanized steel wire mesh 11 is set at the top position of the third layer 3, which is 0.5m-1m down from the top surface of the entire cast-in-place structure. Then, the second galvanized steel wire mesh 12 is set down at a thickness of 500-600mm. That is, the second galvanized steel wire mesh 12 is set at the top position of the first layer 1.

[0057] (3) Cover the surface of the poured body that has reached the design elevation with a moisture-retaining felt and set a humidity sensor to monitor the humidity in real time. Automatically spray the curing agent to keep the moisture-retaining felt ≥90% and keep the concrete surface moist. The curing time is set to 7 days.

[0058] After the cast-in-place foamed lightweight concrete is poured to the design elevation, a moisture-retaining felt is applied to the surface for curing. This felt provides a continuous and stable moist curing environment. During the curing period, maintaining the moisture content of the felt above 90% reduces water evaporation from the foamed lightweight concrete, prevents surface cracking, promotes full cement hydration, and improves the strength and durability of the foamed lightweight concrete. The curing agent is a commercially available product with no special requirements; it is used to moisturize, waterproof, and prevent cracking of the foamed lightweight concrete, improving its quality and durability. Examples include high-efficiency building concrete curing agents.

[0059] In this application, the contradiction between stability and construction efficiency of long-distance pipeline transport of foamed lightweight concrete is better and more systematically resolved through improved construction technology (pipeline lubrication and buffer pouring). Buffer pouring refers to setting the thickness of the pouring layer to 250-300mm, which prevents the foamed lightweight concrete from collapsing or defoaming due to gravity on the underlying foamed lightweight concrete layer caused by excessive thickness.

[0060] The present application will be further described below through specific embodiments.

[0061] All raw materials used in the following examples are commercially available products. The main sources of the raw materials and equipment used in the following examples are as follows: The P·II 52.5R silicate cement was purchased from China Resources Cement (Jiangmen) Co., Ltd., and the model is P·II 52.5R.

[0062] The Grade I fly ash was purchased from Zhongshan Jieanqiao New Material Co., Ltd., and is classified as Class F, Grade I.

[0063] Hydroxypropyl methylcellulose (for slurry, pre-wetting) was purchased from Langfang Longteng New Materials Co., Ltd., model number 100000 mPa·s.

[0064] Hydroxypropyl methylcellulose (used as a foaming agent) was purchased from Sinopharm Reagent, type I, viscosity: 30 mPa.s (Wokai).

[0065] The polycarboxylate superplasticizer was purchased from Zhongyan Building Materials Technology Co., Ltd., model number DA-100.

[0066] The all-in-one machine was purchased from Shandong Naijiu Industrial Equipment Co., Ltd., model number NJFZY-50.

[0067] Polyacrylamide was purchased from Sinopharm Reagent, specification Acros-178045000.

[0068] Polyethyleneimine was purchased from Sinopharm Reagent, specification MW 70,000, 50% aqueous solution (Wokai).

[0069] Polyvinylpyrrolidone was purchased from Sinopharm Reagent, with an average molecular weight of 220,000 and a K60 rating (Wokai).

[0070] The alkoxylated alkyl diols were purchased from: Sinopharm Reagent, 3-methoxy-1,2-propanediol.

[0071] Nano titanium dioxide was purchased from Sinopharm Reagent, with specifications of 99.5% and 500nm (Wokai).

[0072] Triethanolamine was purchased from Sinopharm Reagent, specification Alfa-L04486, 98+.

[0073] Example 1 The foamed lightweight concrete provided in this embodiment, suitable for long-distance pipeline transportation, consists of the following raw materials in parts by weight: P·II 52.5R silicate cement 45.98 parts, grade 1 fly ash 19.71 parts, water 34.16 parts, hydroxypropyl methylcellulose 0.02 parts, polycarboxylate superplasticizer 0.13 parts; The apparent viscosity of hydroxypropyl methylcellulose is 100,000 mPa·s.

[0074] The nano-stabilized foaming agent composition comprises the following raw materials in parts by weight: 1.3 parts polyacrylamide, 4.5 parts polyethyleneimine, 13 parts polyvinylpyrrolidone, 37 parts hydroxypropyl methylcellulose, 3.5 parts triethanolamine, 23.5 parts nano-titanium oxide with hydrophilic surface modification by alkoxylated alkyl diol, and 17.2 parts alkoxylated alkyl diol.

[0075] The method for preparing foamed lightweight concrete in this embodiment includes: Weigh out P·II 52.5R silicate cement, grade I fly ash, and hydroxypropyl methylcellulose and put them into the mixer of the integrated machine and mix for 2 minutes to obtain a mixed dry material; weigh out polycarboxylate superplasticizer and first water and mix them evenly in the water storage tank and then pour them into the mixer and mix them thoroughly with the mixed dry material for 3 minutes to obtain a slurry. A foaming agent solution was prepared by mixing a nano-stabilized foaming agent composition with second water (at 29°C) at a mass ratio of 1:330. After standing for 30 minutes, the solution was connected to an integrated foaming machine to produce a foam cluster with a density of 45 kg / m³. 3 ; The prepared foam group and slurry are simultaneously pumped into the spiked pipe at a volume ratio of 2.30:1 for rapid mixing. The foamed lightweight concrete suitable for long-distance pipeline transportation in this embodiment is obtained at the outlet of the spiked pipe.

[0076] A 500m long, DN150mm high-pressure hose was used as the pumping pipeline. Before construction, the inner wall of the high-pressure hose was wetted with a 0.1% hydroxypropyl methylcellulose aqueous solution to reduce flow resistance. The specific steps included: (1) Pipeline pretreatment: First, rinse the inner wall of the pipeline with tap water, and then blow it dry with compressed air to remove oil and particles; (2) Solution preparation: Dissolve HPMC in hot water at 60℃ to prepare an aqueous solution of HPMC with a mass concentration of 0.01%, and cool it naturally to 25±2℃; (3) Circulating coating: First, fill the pumping pipeline with HPMC aqueous solution, and then circulate the HPMC aqueous solution in the 500m pumping pipeline for 2-4 minutes to ensure uniform wetting; (4) Drying and film formation: Drain the excess liquid and allow it to dry naturally for 40 minutes to form a dense lubricating layer.

[0077] During the pouring process, the inlet of the high-pressure hose is connected to the outlet of the spiked concrete delivery pipe. The outlet of the high-pressure hose is located in the construction area. The foamed lightweight concrete, suitable for long-distance pipeline transportation in this embodiment, is pumped to the construction area for pouring. During construction, the pumping pressure is set to 11.5 MPa, and the flow rate is controlled at 2.0 m / s. Furthermore, samples are taken and retained at the 0m and 500m outlets of the pumping pipeline for future testing.

[0078] The specific pouring process is as follows: the poured body (i.e., the building structure) is divided into several construction sections according to functional areas; then, each construction section is further divided into several pouring layers according to height, with the height (i.e., thickness) of each pouring layer controlled between 250-300mm; finally, each pouring layer is further divided into several pouring blocks according to the cement pump flow rate and the initial setting time of the cement slurry (in actual construction, there may be errors due to human operation, but as long as the thickness is within this range, it is acceptable). Formwork is set up for the segmented, layered, and block-shaped poured body, and protective walls are set on the open sides of the poured body. The foamed lightweight concrete suitable for long-distance pipeline transportation in this embodiment is poured according to the segmented, layered, and block-shaped process. The construction time for pouring within a single pouring block is controlled within the initial setting time of the cement slurry (within 45 minutes in summer). The upper layer is poured only after the lower layer has fully set, until the design elevation is reached.

[0079] During the pouring process, galvanized steel wire mesh (100mm x 100mm aperture) is pre-embedded at the required locations. A layer of galvanized steel wire mesh is installed 0.7m down from the top surface of the poured body, and then another layer of galvanized steel wire mesh is installed every 600mm of thickness downwards.

[0080] After the cast-in-place foamed lightweight concrete is poured to the design elevation, a moisture-retaining felt is covered on the surface. A humidity sensor monitors the humidity in real time and an automatic curing agent is sprayed to keep the moisture content of the felt above 90% and keep the concrete surface moist. The curing time is set to 7 days.

[0081] Example 2 The foamed lightweight concrete suitable for long-distance pipeline transportation provided in this embodiment has the same raw material composition of slurry and nano-stabilized foaming agent composition as in Example 1.

[0082] The method for preparing foamed lightweight concrete in this embodiment includes: Weigh out P·II 52.5R silicate cement, grade I fly ash, and hydroxypropyl methylcellulose and put them into the mixer of the integrated machine and mix for 2 minutes to obtain a mixed dry material; weigh out polycarboxylate superplasticizer and first water and mix them evenly in the water storage tank and then pour them into the mixer and mix them thoroughly with the mixed dry material for 3 minutes to obtain a slurry. A foaming agent solution was prepared by mixing a nano-stabilized foaming agent composition with second water (at 29°C) at a mass ratio of 1:330. After standing for 30 minutes, the solution was connected to an integrated foaming machine to produce a foam cluster with a density of 45 kg / m³. 3 ; The prepared foam group and slurry are simultaneously pumped into the spiked pipe at a volume ratio of 1.71:1 for rapid mixing. The foamed lightweight concrete suitable for long-distance pipeline transportation in this embodiment is obtained at the outlet of the spiked pipe.

[0083] A high-pressure flexible hose with a length of 500m and a diameter of DN150mm was used as the pumping pipeline.

[0084] Before construction, the inner wall of the high-pressure hose is wetted with an aqueous solution of hydroxypropyl methylcellulose (0.1% by mass) to reduce flow resistance. The specific steps are the same as in Example 1.

[0085] During the pouring process, the inlet of the high-pressure hose is connected to the outlet of the spiked concrete delivery pipe. The outlet of the high-pressure hose is located in the construction area. The foamed lightweight concrete, suitable for long-distance pipeline transportation in this embodiment, is pumped to the construction area for pouring. During construction, the pumping pressure is set to 12.5 MPa, and the flow rate is controlled at 2.0 m / s. Furthermore, samples are taken and retained at the 0m and 500m outlets of the pumping pipeline for future testing.

[0086] The specific pouring process is as follows: the poured body (i.e., the building structure) is divided into several construction sections according to functional areas; then, each construction section is further divided into several pouring layers according to height, with the height (i.e., thickness) of each pouring layer controlled between 250-300mm; finally, each pouring layer is further divided into several pouring blocks according to the cement pump flow rate and the initial setting time of the cement slurry (in actual construction, there may be errors due to human operation, but as long as the thickness is within this range, it is acceptable). Formwork is set up for the segmented, layered, and block-shaped poured body, and protective walls are set on the open sides of the poured body. The foamed lightweight concrete suitable for long-distance pipeline transportation in this embodiment is poured according to the segmented, layered, and block-shaped process. The construction time for pouring within a single pouring block is controlled within the initial setting time of the cement slurry (within 45 minutes in summer). The upper layer is poured only after the lower layer has fully set, until the design elevation is reached.

[0087] During the pouring process, galvanized steel wire mesh (100mm x 100mm aperture) is pre-embedded at the required locations. A layer of galvanized steel wire mesh is installed 0.7m down from the top surface of the poured body, and then another layer of galvanized steel wire mesh is installed every 600mm of thickness downwards.

[0088] After the cast-in-place foamed lightweight concrete is poured to the design elevation, a moisture-retaining felt is covered on the surface. A humidity sensor monitors the humidity in real time and an automatic curing agent is sprayed to keep the moisture content of the felt above 90% and keep the concrete surface moist. The curing time is set to 7 days.

[0089] Comparative Example 1 Comparative Example 1 was identical to Example 1 except that it was not pre-lubricated with an aqueous solution of hydroxypropyl methylcellulose before construction.

[0090] Comparative Example 2 Comparative Example 2 was identical to Example 1 except that the thickness of the cast layer was set to 550-600 mm and no galvanized steel wire mesh was used.

[0091] Comparative Example 3 Comparative Example 3 was identical to Example 1 except that no galvanized steel wire mesh was installed in the pouring layer.

[0092] In Examples 1-2 and Comparative Example 1, samples were taken at the 0m and 500m outlets of the pumping pipeline, and their wet density, dry density, flowability, specimen compressive strength, and specimen water absorption rate were tested. The bubble survival rate from 0m to 500m was also calculated. The test results are shown in Table 1.

[0093] Table 1

[0094] As shown in Table 1, the wet density growth rates of the foamed lightweight concrete prepared in Examples 1 and 2, suitable for long-distance pipeline transportation, were 6.08% and 3.55% respectively from 0m to 500m, and the fluidity loss rates were 11.25% and 12.82% respectively. In addition, due to the compression and resistance experienced by the foamed lightweight concrete during the 500m long-distance transportation, a small amount of foam ruptured, resulting in an increase in slurry density. Correspondingly, the compressive strength increased by 23.47% and 22.60%, and the water absorption decreased by 2.89% and 12.23%. In contrast, Comparative Example 1, which did not undergo pipeline pre-lubrication treatment, showed a wet density growth rate of 18.96% and a fluidity loss rate of 13.76% after 500m long-distance transportation. The excessive resistance along the pipeline during construction of the foamed lightweight concrete during long-distance transportation led to pumping difficulties, reducing its quality and stability. Correspondingly, the compressive strength increased by 47.96%, and the water absorption decreased by 17.63%.

[0095] In Example 1 and Comparative Examples 2 and 3, samples were taken from the cast bodies to test the wet and dry density deviations of the surface and core layers, the compressive strength deviation, the water absorption deviation, and the number of cracks per unit area on the surface of the hardened cast body. The test results are shown in Table 2.

[0096] Table 2

[0097] According to the data in Table 2, Example 1 (250-300mm layer thickness + galvanized steel wire mesh) showed the best performance in terms of density uniformity and overall performance: wet density deviation was only 4.25%, dry density deviation was 2.80%, compressive strength deviation was 3.31%, water absorption deviation was 11.50%, and only 2 cracks appeared on the surface after hardening. This is attributed to the "constraint-dispersion" effect of the galvanized steel wire mesh: the galvanized steel wire mesh effectively inhibited slurry flow and air bubble migration, reducing the density difference caused by settlement or floating in the upper and lower parts of the poured layer, making the internal structure of the material more uniform. Comparative Example 2 (550-600mm layer thickness without steel wire mesh) had a wet density deviation as high as 25.80%, a dry density deviation of 23.09%, a compressive strength deviation of 17.90%, and a water absorption deviation of 11.50%. The moisture content deviation was 65.60%, and the number of cracks increased to 6. The main reason was that the excessive layer thickness (550-600mm) aggravated the self-weight settling of the slurry and the floating of air bubbles, resulting in severe density stratification between the upper and lower layers. In addition, the lack of galvanized steel wire mesh restraint could not suppress air bubble migration and local defects, ultimately leading to large fluctuations in mechanical properties, increased water absorption deviation, and more cracks. Although the layer thickness of Comparative Example 3 (250-300mm layer thickness without steel wire mesh) was reasonably controlled, the lack of physical restraint from galvanized steel wire mesh increased the risk of air bubble migration and merging, and caused uneven local density (wet density deviation of 17.60% and dry density deviation of 16.88%), which in turn led to an expansion of the compressive strength deviation to 55.37%, the water absorption deviation to 51.25%, and 14 surface cracks.

[0098] In summary, after a 500m long-distance transport, the bubble survival rates of the foamed lightweight concrete in Examples 1 and 2 reached 94.3% and 96.6%, respectively, while the bubble survival rate of Comparative Example 1, which did not undergo pipeline pre-lubrication treatment, was 84.1%. The construction method for foamed lightweight concrete suitable for long-distance pipeline transport provided in this application can indeed enable foamed lightweight concrete to exhibit higher slurry foam stability during transport over distances up to 500m. Furthermore, the synergistic effect of controlling the 250-300mm layer thickness of the pouring layer and the use of galvanized steel wire mesh is key to improving the density uniformity, mechanical stability, and crack resistance of the foamed lightweight concrete pour.

[0099] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of this application.

Claims

1. A construction method for foamed lightweight concrete suitable for long-distance pipeline transportation, characterized in that, Includes the following steps: High-pressure hoses with a diameter of DN100mm-DN150mm were selected as pumping pipelines; Before conveying the foamed lightweight concrete, the pumping pipe is pre-wetted with a 0.05%-0.15% aqueous solution of hydroxypropyl methylcellulose to form a lubricating layer on the inner wall of the pumping pipe. The foamed lightweight concrete is transported to the construction area through the pumping pipeline for pouring.

2. The construction method for foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 1, characterized in that, The process of pre-wetting the pumping pipeline with a 0.05%-0.15% (w / w) aqueous solution of hydroxypropyl methylcellulose specifically includes the following steps: First, rinse the inner wall of the pumping pipe with tap water, and then dry it with compressed air; Dissolve HPMC in hot water at 50-70℃ to prepare an HPMC aqueous solution with a mass concentration of 0.05%-0.15%, and allow it to cool naturally to 25±2℃. First, fill the pumping pipeline with the HPMC aqueous solution, and then circulate the HPMC aqueous solution in the pumping pipeline for 2-4 minutes; Drain excess liquid and allow to air dry for 30-45 minutes to form a dense lubricating layer.

3. The construction method for foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 1, characterized in that, When the foamed lightweight concrete is transported to the construction area through the pumping pipeline, a hydraulic piston pump is used to transport the foamed lightweight concrete, with a pumping pressure of 10-15MPa and a controlled flow rate of 1.5-2.0 m / s.

4. The construction method for foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 1, characterized in that, The diameter of the pumping pipeline is DN150mm.

5. The construction method of foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 1, characterized in that, The pouring process specifically includes the following steps: (1) According to the height, width and length of the casting body, the casting body is divided into several casting blocks by segmenting, layering and blockping, and templates are set up for the casting body that has been segmented, layered and blockped. (2) Pouring: After the pouring of the first layer of the pouring block is completed, the pouring of the next layer of the pouring block is carried out after the pouring block of this layer has finally set, until the design elevation is reached; (3) Cover the surface of the cast body that has reached the design elevation with a moisture-retaining felt and set a humidity sensor to monitor the humidity in real time. Automatically spray a curing agent to keep the moisture-retaining felt at ≥90% and keep the surface of the cast body moist. The curing time is set to 7 days.

6. The construction method of foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 5, characterized in that, In step (2), the height of each of the pouring blocks is controlled at 250-300mm, the pouring time interval between layers is controlled within 45min during the summer operation period, and the pouring time interval between layers is controlled within 90min during the winter operation period.

7. The construction method for foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 5, characterized in that, The process of dividing the cast-in-place body into several casting blocks by segmenting, layering, and slabming includes the following steps: The cast-in-place body is divided into several construction sections according to functional areas; Each construction section is further divided into several layers according to its height, with the height of each layer controlled between 250-300mm. Each layer of the pouring layer is further divided into several pouring blocks according to the cement pumping flow rate and the initial setting time of the cement slurry.

8. The construction method of foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 5, characterized in that, Before proceeding to step (2), the following steps are also included: Pre-embedded galvanized steel wire mesh; The galvanized steel wire mesh has a mesh size of 50-150 mm × 50-150 mm.

9. The construction method of foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 8, characterized in that, The galvanized steel wire mesh is positioned 0.5m-1m below the top surface of the cast body, and another layer of the galvanized steel wire mesh is installed every 500-600mm of thickness.

10. The construction method of foamed lightweight concrete suitable for long-distance pipeline transportation according to claim 1, characterized in that, The foamed lightweight concrete includes a slurry and a foam group; The volume ratio of the foam cluster to the slurry is 1.67-2.5:1; The slurry, by weight, comprises the following raw materials: 30-50 parts cement, 10-25 parts fly ash, 0.02-0.04 parts hydroxypropyl methylcellulose, 0.08-0.2 parts water-reducing agent, and 25-40 parts first water; The foam cluster was prepared from a nano-stabilized foaming agent composition and second water; The mass ratio of the nano-stabilized foaming agent composition to the second water is 1:300-350; The nano-stabilized foaming agent composition comprises, by weight parts: Polyacrylamide 0.5-5 parts, polyethyleneimine 3-20 parts, polyvinylpyrrolidone 10-20 parts, hydroxypropyl methylcellulose 35-50 parts, triethanolamine 1-5 parts, surface-modified hydrophilic nano-titanium oxide 20-35 parts, surfactant 15-30 parts.

Images