Slurry bone polymerized steel pipe concrete and construction method thereof

Abstract

The invention provides slurry bone polymerized steel pipe concrete and a construction method thereof, and relates to the technical field of steel pipe concrete materials and construction methods. The slurry bone polymerization steel tube concrete is composed of aggregates which are compactly piled in a tube in advance and slurry which is injected later, and the aggregates are coarse aggregates in a single particle size range, are high in proportion and have a strong effect of restraining the shrinkage of the slurry; industrial sand, a nano material, an additive and the like are doped into the slurry to adjust the performance, so that the slurry with high fluidity, micro-expansibility and excellent mechanical properties is formed, the slurry can permeate and wrap aggregate in all directions and fill pores, and the time-sharing expansion of the slurry can further compensate for later hardening shrinkage. During construction, aggregate is directly conveyed to a site and put into a pipe, and reciprocating transportation energy consumption is reduced; the slurry is prepared by a nearby slurry preparation machine, so that the construction investment of a large mixing plant is saved; the problem that the pipe is blocked after aggregate and slurry are separated in the conventional concrete integral pumping process is solved, the shrinkage and void risk of the concrete in the pipe is small, cooperative stress of the combined structure is greatly guaranteed, and the economic and technical advantages are remarkable.

Description

Technical Field

[0001] This invention relates to the technical field of building materials and construction methods, particularly to the technical field of steel-concrete composite materials and construction methods, specifically to a grout-aggregate polymer steel-concrete composite and its construction method. Background Technology

[0002] Concrete-in-steel tube (CST) involves directly pouring concrete into a tube, eliminating the need for formwork and reinforcing steel. The resulting CST structure is lightweight, high-strength, earthquake-resistant, has excellent spanning capacity, good toughness, and low cost, making it commonly used as a primary load-bearing structure in bridges, tunnels, and building construction. However, compared to its numerous advantages, the process and quality of CST pouring still have significant room for improvement. Currently, CST pouring methods include pumping and high-throw casting. Taking pumping as an example, concrete is pressurized and transported through a pump pipe into the steel tube to be poured. The pump pipe alignment is specifically designed based on site topography and environment. Before formal pouring, detailed design of the pump pipe layout, installation process, and construction organization are required. The steel pipe is pre-soaked with a uniformly proportioned grout, and then all the grout is pumped out. If the steel pipe is too long or has a large elevation difference, staged relay pumping is necessary, with a pumping platform at each pumping location. Therefore, the pre-pumping preparation work is extensive, the process is relatively complex, and the cost of temporary pumping measures is high. Typically, concrete is pumped into steel pipes in volumes of hundreds of cubic meters at a time, lasting 6-12 hours, at a pressure of approximately 10 MPa. Maintaining the concrete in good condition under such high pressure and extended pumping time is challenging. During construction, concrete cracking and segregation frequently occur, leading to pipe blockages and impacting construction progress and project quality. Furthermore, the concrete undergoes drying shrinkage during hardening. Under ambient temperature, the difference in thermal expansion coefficients between the concrete and steel causes inconsistent volume changes, resulting in voids. This prevents the steel pipe and concrete from forming a dense composite structure to jointly bear external loads, negating the advantages of a combined structure. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of complex construction of concrete pouring inside the pipe, easy pipe blockage, and debonding (between concrete and steel pipe) in existing steel pipe concrete materials, and to propose a paste-aggregate polymer steel pipe concrete and its construction method.

[0004] To achieve the above-mentioned objective, the present invention provides a slurry-aggregate polymer steel pipe concrete, comprising the following raw materials by volume: 55-57 parts of aggregate and 43-45 parts of slurry; The slurry-aggregate polymer steel pipe concrete is formed by filling the aggregate piled in the steel pipe with slurry and then curing it. The aggregate is coarse aggregate with a particle size range of 9.5-20 mm, forming a porosity of approximately 41-43% (95% confidence level); or coarse aggregate with a particle size range of 16-31.5 mm, forming a porosity of approximately 40%-42% (95% confidence level). The slurry per cubic meter comprises the following raw materials by weight: Total adhesive material: 800-1200 kg, wherein the total adhesive material includes cement, fly ash and nano-silica; The components include 500-1000 kg of cement, 200-500 kg of fly ash, and 0.4-6 kg of nano-silica. It also includes 700-1000 kg of industrial sand, 350-450 kg of water, 8-24 kg of water-reducing agent, and 30-50 kg of expanding agent; The water-cement ratio of the slurry is 0.30-0.45; The mortar-to-cement ratio of the slurry is 0.8-1.7; The industrial sand has a particle size of 0.075-2.36 mm, a fineness modulus of no more than 2.0, a porosity of 20-40%, a water absorption rate of 0.8-5%, and a silica content of 35-70%.

[0005] This invention provides a paste-aggregate polymer steel-tube concrete system. It utilizes larger-diameter coarse aggregate as the aggregate, thereby inhibiting slurry shrinkage through the skeleton structure. Furthermore, the high aggregate content further reduces shrinkage, significantly lowering the probability of separation between the steel tube and concrete due to concrete shrinkage. The method of pre-filling the steel tube with aggregate before injecting the slurry avoids the complex preparation and processes of conventional monolithic concrete mixing and pouring, and eliminates the risks of segregation and pipe blockage during pumping and high-throwing pouring. This invention eliminates the need for large-scale mixing plants and pump pipes, utilizes locally sourced materials, and boasts a simple and efficient process, reducing construction costs and shortening the construction cycle, making it suitable for large-scale application.

[0006] The specific type of cement can be adjusted according to the strength requirements of the steel-concrete composite.

[0007] Preferably, when the strength grade of the grout-aggregate polymerized steel pipe concrete is not greater than C60 (C40, C50, C60, etc.), the aggregate is coarse aggregate with a particle size of 16-31.5mm, and the ratio of the parent rock compressive strength of the coarse aggregate to the design compressive strength of the concrete is not less than 1.5; a skeleton with a porosity of about 40%-42% (confidence level 95%) is formed by using coarse aggregate with a particle size range of 16-31.5mm, and grout of the corresponding strength grade is injected to wrap the coarse aggregate and fill the voids in the coarse aggregate, and the two polymerize to form grout-aggregate polymerized steel pipe concrete of the corresponding strength grade; When the strength grade of the slurry-aggregate polymerized steel pipe concrete is greater than C60 (C70, C80, C100, etc.), the aggregate is coarse aggregate with a particle size of 9.5-20mm, and the ratio of the compressive strength of the parent rock of the coarse aggregate to the design compressive strength of the concrete is not less than 1.3; a skeleton with a porosity of about 41-43% (confidence level 95%) is formed, and slurry of corresponding strength is injected to wrap the coarse aggregate and fill the voids in the coarse aggregate. The two polymerize to form slurry-aggregate polymerized concrete of the corresponding strength grade; preferably, the particle size of the coarse aggregate and the porosity formed are more conducive to improving the strength of the slurry-aggregate polymerized concrete.

[0008] The industrial sand mentioned here refers to industrial waste materials that can be used undisturbed or processed to replace natural river sand, and has the advantages of low cost, wide availability, and solid waste resource utilization. By controlling the particle size, fineness modulus, and specific surface area of ​​the industrial sand, the proportion of reactive fine aggregates in the industrial sand can be increased. The high silica content and large specific surface area of ​​industrial sand can promote the reaction with cement hydration products, enhance the strength and durability of slurry-aggregate polymerized steel pipe concrete, and help reduce raw material costs.

[0009] Industrial sand has no sharp edges and a significant ball bearing effect, which increases the flowability of the slurry. Its porous surface can store moisture, providing sufficient moisture for subsequent internal curing, further reducing the amount of slurry drying shrinkage, and lowering the risk of separation from the steel pipe after curing.

[0010] Preferably, when the strength grade of the slurry-aggregate polymerized steel pipe concrete is not greater than C40 (C20, C30, C40, etc.), the mortar-cement ratio is in the range of 0.8-1.5, and the silica content of the industrial sand is 35%-50%; when the strength grade of the slurry-aggregate polymerized steel pipe concrete is greater than C40 (C50, C60, C80, etc.), the mortar-cement ratio is 1.5-1.7, and the silica content of the industrial sand is 50%-70%; wherein, not less than 50% of the industrial sand needs to be finely ground, and the specific surface area of ​​the finely ground industrial sand reaches 100-300 m². 2 / kg.

[0011] Preferably, the type of fly ash is adjusted according to the performance requirements of the slurry-aggregate polymerized steel pipe concrete: when the strength grade of the slurry-aggregate polymerized steel pipe concrete is not greater than C40 (C20, C30, C40, etc.), then Class F II fly ash is selected; when the strength grade of the slurry-aggregate polymerized steel pipe concrete is greater than C40 (C50, C60, C80, etc.), then Class F I fly ash or fly ash microspheres are selected. The preferred type of fly ash can better control the shrinkage of the slurry, improve the fluidity of the slurry, and optimize the cost performance of the slurry-aggregate polymerized steel pipe concrete.

[0012] The nano-silica further fills the pores between the aggregate and the slurry, reduces the porosity of the interface transition zone, optimizes the performance of the interface transition zone, makes the structure denser, and improves the mechanical properties by more than 15%. Preferably, the particle size of the nano-silica is 50-200nm. The larger the particle size, the less conducive it is to filling the pores, and the smaller the particle size, the worse the dispersibility.

[0013] Preferably, when the strength grade of the grout-aggregate polymerized steel pipe concrete is not greater than C40 (C20, C30, C40, etc.), the water reduction rate of the water-reducing agent is not less than 25%; when the strength grade of the grout-aggregate polymerized steel pipe concrete is greater than C40 (C50, C60, C80, etc.), the water reduction rate of the water-reducing agent is not less than 30%; more preferably, the water-reducing agent is a comb-shaped polycarboxylate water-reducing agent, such as polyester-type polycarboxylate water-reducing agent or polyether-type polycarboxylate water-reducing agent.

[0014] Preferably, each cubic meter of the slurry also includes 30-50 kg of expanding agent, which is a calcium-magnesium composite expanding agent with early, middle and late time-phase expansion effects.

[0015] Preferably, each cubic meter of the slurry further includes 0.08-0.36 kg of a retarder, wherein the retarder is a carbohydrate retarder, including at least one selected from glucose, fructose, and sucrose. The addition of the retarder can prolong the setting time of concrete, reduce the rate of heat release from hydration, and maintain the workability of the concrete.

[0016] More preferably, the retarder accounts for 0.1 to 0.3‰ of the total adhesive material mass.

[0017] In this invention, the slurry is not mixed with the aggregate, which avoids the water being carried away by the aggregate, greatly improving the slurry's fluidity and ensuring that the slurry fully fills and coats the aggregate. Preferably, the initial flow cone time of the slurry is no more than 18s, and the 3-hour flow cone time is no more than 35s; the initial truncated cone flowability is no less than 390mm, and the 3-hour truncated cone flowability is no less than 340mm; and the bleeding rate is no more than 1% under a pressure of 0.36MPa.

[0018] Preferably, the 28-day shrinkage-expansion rate of the slurry satisfies the formula: δ △ +(δv+δc)≤r; where r is the design value of the 28-day shrinkage expansion rate; δ △ δv is the design value for the expansion rate of the slurry; δv is the design value for the shrinkage rate of the coarse aggregate; δc is the design value for the shrinkage rate of the slurry material.

[0019] Furthermore, in order to achieve the above-mentioned objectives, the present invention provides a construction method for grout-aggregate polymer steel pipe concrete, comprising the following steps: Step 1: Adjust the tilt angle of the steel pipe and lay the bottom with grout of the same strength; Step 2: Fill the inclined steel pipe with aggregate, allowing it to slide down and compact under its own weight; Step 3: After the aggregate filling inside the pipe is completed, restore it to the designed tilt angle or keep the state of Step 1 unchanged, and inject grout from one horizontal end to the other or from bottom to top; alternatively, holes can be opened in the pipe body in the state of Step 1, and grout can be poured directly into the holes. Step 4: Observe whether the grout is filled densely by opening holes in the top of the steel pipe, the pipe body, or setting grout outlet pipes at the pipe ends; Step 5: After filling and compacting, wait for the strength to develop until it meets the design requirements, thus forming grout-aggregate polymer steel pipe concrete.

[0020] This invention provides a construction method for slurry-aggregate polymerized steel-tube concrete. During construction, aggregates are directly transported to the site and added into the steel pipes, reducing the energy consumption of transporting aggregates from mining to the mixing plant and then from the mixing plant to the pouring site. The slurry is prepared locally using a slurry mixer, saving on the construction investment of large mixing plants. It avoids the pipe blockage problems caused by aggregate segregation during conventional concrete pumping and pouring. Furthermore, by controlling the slurry's workability, the slurry ensures sufficient filling and encapsulation of the aggregates. The high aggregate content constrains slurry shrinkage; the slurry is prepared separately, and the expansion agent in the slurry only affects the slurry, resulting in higher effectiveness and reducing the risk of shrinkage and voids in the slurry-aggregate polymerized steel-tube concrete, greatly ensuring the coordinated stress distribution of the composite structure. This construction method involves fewer steps, is convenient to operate, has high construction efficiency, good quality, and low cost, making it suitable for large-scale in-tube concrete construction in steel-tube concrete systems.

[0021] Preferably, in step 1, the steel pipe to be filled with aggregate should be tilted at an angle of 30°-90° to the ground, and a base layer of 8-15cm thick slurry of the same strength should be laid in advance. When the length of the steel pipe to be filled exceeds 30m, holes should be made in the pipe body, and the aggregate should be filled in sections with a section length of no more than 15m. Alternatively, a chute or other method can be used to extend into the pipe to assist in conveying the aggregate, ensuring that the aggregate slippage distance is no more than 15m.

[0022] Preferably, in step 3, the horizontal pumping distance of the slurry should not exceed 100m and the vertical pouring height difference should not exceed 30m. If these distances are exceeded, the slurry should be pumped in sections, and the pumping pressure should not exceed 2MPa. The opening diameter of the slurry for direct pouring should be 2-5cm.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. A slurry with excellent flow properties and mechanical and volume stability was developed. Based on the excellent performance of the slurry, a sequential method was developed in which the aggregate is first put into the steel pipe and then the slurry is poured in. This allows the two to fully contact each other to form slurry-aggregate polymer steel pipe concrete. This method avoids the complicated construction preparation of conventional concrete and also avoids the problems of segregation and pump blockage that occur during the overall mixing and pouring of conventional concrete. 2. Compared with conventional concrete, grout-aggregate polymer steel tube concrete has a larger proportion of aggregate, which fully mobilizes the skeleton function and further restricts the drying shrinkage of the concrete inside the tube. With the use of expansion agent, the expansion and shrinkage can be offset, so that the steel tube and grout-aggregate polymer steel tube concrete can be closely bonded and work together, breaking through the bottleneck restricting the development of steel tube concrete technology. 3. In conventional concrete, cementitious materials account for a relatively high proportion of the cost. However, in grout-aggregate polymer steel pipe concrete, due to the high proportion of aggregate, the small total surface area, and the small amount of grout used, the material cost is lower compared with conventional concrete of the same grade. 4. The cost of transporting aggregates in conventional concrete accounts for about 25% of the total cost of concrete. In this invention, aggregates can be sourced locally and used nearby, saving on the cost of transporting aggregates back and forth. 5. Pulp-aggregate polymer steel pipe concrete has low requirements for construction equipment, saves energy, generates less dust pollution, and produces less construction noise. Each cubic meter of pulp-aggregate polymer steel pipe concrete reduces carbon emissions by about 25%. Detailed Implementation

[0024] To more clearly describe the inventive objectives, technical solutions, and advantages of the specific embodiments of this invention, the solutions in the specific embodiments will be described in detail below with reference to the specification of this invention. The specific technical solutions involved in the following specific embodiments are merely for the purpose of clearly and completely describing the innovative technical solutions of this invention. They are only a part of the specific implementation methods that this invention can adopt, not all the embodiments, and should not be construed as limiting the innovative solutions of this invention. Any solution that adopts the same inventive concept as this invention should be included within the protection scope of this invention.

[0025] For those skilled in the art, when understanding the solutions described in the specific embodiments of the present invention, conventional technical manuals in the field can be consulted. At the same time, appropriate understandings or adjustments can be made to the above-mentioned terms to deduce the same or similar technical solutions without creative effort.

[0026] In order to examine the excellent performance of the slurry-aggregate polymer steel pipe concrete obtained by the technical solution of the present invention, the following formula adjustments were made, and performance comparisons were carried out through experiments, and material costs were calculated.

[0027] Example 1 A type of slurry-aggregate polymerized steel pipe concrete, wherein the strength grade of the slurry-aggregate polymerized steel pipe concrete in this embodiment is C20, specifically comprising the following raw materials by volume: 57 parts aggregate, 43 parts slurry; aggregate particle size is 16-31.5mm; compressive strength of aggregate is not less than 30MPa; Each cubic meter of slurry comprises the following raw materials mixed together: 500 kg of cement, 350 kg of fly ash (Class F, Grade II fly ash), 900 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.9, porosity 36%, water absorption 2.5%, silica content 38%), 380 kg of water, 4.1 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent with a water reduction rate greater than 25%), 0.4 kg of nano silica, and 35 kg of expanding agent (calcium-magnesium composite expanding agent). In this embodiment, the total adhesive content is 850.4 kg (cement + fly ash + nano silica). The water-cement ratio is 0.45; the mortar-mortar ratio is 0.94; and the density of the mortar-aggregate polymer steel pipe concrete is 2380 kg / m³.

[0028] Example 2 A type of grout-aggregate polymerized steel pipe concrete, wherein the strength grade of the grout-aggregate polymerized steel pipe concrete in this embodiment is C30, specifically comprising the following raw materials by volume: 57 parts aggregate, 43 parts slurry; aggregate particle size is 16-31.5mm; compressive strength of aggregate is not less than 45MPa; Each cubic meter of slurry comprises the following raw materials mixed together: 520 kg of cement, 400 kg of fly ash (Class F, Grade II fly ash), 840 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.9, porosity 36%, water absorption 2.5%, silica content 38%), 400 kg of water, 5.4 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent with a water reduction rate greater than 25%), 0.4 kg of nano silica, and 35 kg of expanding agent (calcium-magnesium composite expanding agent). In this embodiment, the total adhesive content is 920.4 kg (cement + fly ash + nano silica). The water-cement ratio is 0.43; the mortar-mortar ratio is 1.1; and the density of the mortar-aggregate polymer steel pipe concrete is 2400 kg / m³.

[0029] Example 3 A type of grout-aggregate polymerized steel pipe concrete, wherein the strength grade of the grout-aggregate polymerized steel pipe concrete in this embodiment is C40, specifically comprising the following raw materials by volume: 57 parts aggregate, 43 parts slurry; aggregate particle size is 16-31.5mm; compressive strength of aggregate is not less than 60MPa; Each cubic meter of slurry comprises the following raw materials mixed together: 550 kg of cement, 460 kg of fly ash (Class F, Grade II fly ash), 770 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.8, porosity 36%, water absorption 2.5%, silica content 38%), 400 kg of water, 6.8 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent with a water reduction rate greater than 25%), 1 kg of nano silica, and 40 kg of expanding agent (calcium-magnesium composite expanding agent). In this embodiment, the total adhesive content is 1011 kg (cement + fly ash + nano silica). The water-cement ratio is 0.4; the mortar-mortar ratio is 1.31; and the density of the mortar-aggregate polymer steel pipe concrete is 2420 kg / m³.

[0030] Example 4 A type of grout-aggregate polymerized steel pipe concrete, wherein the strength grade of the grout-aggregate polymerized steel pipe concrete in this embodiment is C50, specifically comprising the following raw materials by volume: 56 parts aggregate, 44 parts slurry; aggregate particle size is 16-31.5mm; aggregate compressive strength is not less than 75MPa; Each cubic meter of slurry comprises the following raw materials mixed together: 620 kg of cement, 460 kg of fly ash (Class F, Grade I fly ash), 700 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.7, porosity 37%, water absorption 2.6%, silica content 55%), 420 kg of water, 7.5 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent with a water reduction rate greater than 30%), 1.8 kg of nano silica, and 40 kg of expanding agent (calcium-magnesium composite expanding agent). In this embodiment, the total adhesive content is 1062 kg (cement + fly ash + nano silica). The water-cement ratio is 0.4; the mortar-mortar ratio is 1.52; and the density of the mortar-aggregate polymer steel pipe concrete is 2450 kg / m³.

[0031] Example 5 A type of grout-aggregate polymerized steel tube concrete, wherein the strength grade of the grout-aggregate polymerized steel tube concrete in this embodiment is C60, specifically comprising the following raw materials by volume: 56 parts aggregate, 44 parts slurry; aggregate particle size is 16-31.5mm; compressive strength of aggregate is not less than 90MPa; Each cubic meter of slurry comprises the following raw materials mixed together: 650 kg of cement, 440 kg of fly ash (Class F, Grade I fly ash), 710 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.7, porosity 37%, water absorption 2.6%, silica content 55%), 410 kg of water, 8 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent with a water reduction rate greater than 30%), 2.6 kg of nano silica, and 40 kg of expanding agent (calcium-magnesium composite expanding agent). In this embodiment, the total adhesive content is 1093 kg (cement + fly ash + nano silica). The water-cement ratio is 0.38; the mortar-mortar ratio is 1.54; and the density of the mortar-aggregate polymer steel pipe concrete is 2480 kg / m³.

[0032] Example 6 A type of grout-aggregate polymerized steel tube concrete, wherein the strength grade of the grout-aggregate polymerized steel tube concrete in this embodiment is C70, specifically comprising the following raw materials by volume: 55 parts aggregate, 45 parts slurry; aggregate particle size is 9.5-20mm; compressive strength of aggregate is not less than 91MPa; Each cubic meter of slurry comprises the following raw materials mixed together: 750kg of cement, 380kg of fly ash (Class F, Grade I fly ash), 720kg of industrial sand (particle size 0.075-2.36mm, fineness modulus 1.7, porosity 37%, water absorption 3%, silica content 55%), 390kg of water, 10.8kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent with a water reduction rate greater than 30%), 4kg of nano silica, and 45kg of expanding agent (calcium-magnesium composite expanding agent). In this embodiment, the total adhesive content is 1134 kg (cement + fly ash + nano silica). The water-cement ratio is 0.34; the mortar-mortar ratio is 1.58; and the density of the mortar-aggregate polymer steel pipe concrete is 2500 kg / m³.

[0033] Example 7 A type of grout-aggregate polymerized steel tube concrete, wherein the strength grade of the grout-aggregate polymerized steel tube concrete in this embodiment is C80, specifically comprising the following raw materials by volume: 55 parts aggregate, 45 parts slurry; aggregate particle size is 9.5-20mm; compressive strength of aggregate is not less than 104MPa; Each cubic meter of slurry comprises the following raw materials mixed together: 850kg of cement, 300kg of fly ash (fly ash microspheres), 720kg of industrial sand (particle size of industrial sand is 0.075-2.36mm, fineness modulus is 1.6, porosity is 37%, water absorption rate is 3%, and silica content is 70%), 370kg of water, 15.4kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent with a water reduction rate greater than 30%), 4.5kg of nano silica, and 45kg of expanding agent (calcium-magnesium composite expanding agent). In this embodiment, the total adhesive content is 1155 kg (cement + fly ash + nano silica). The water-cement ratio is 0.32; the mortar-mortar ratio is 1.6; and the density of the mortar-aggregate polymer steel pipe concrete is 2520 kg / m³.

[0034] Example 8 A type of grout-aggregate polymerized steel pipe concrete, wherein the strength grade of the grout-aggregate polymerized steel pipe concrete in this embodiment is C100, specifically comprising the following raw materials by volume: 55 parts aggregate, 45 parts slurry; aggregate particle size is 9.5-20mm; aggregate compressive strength is not less than 130MPa; Each cubic meter of slurry comprises the following raw materials mixed together: 980kg of cement, 200kg of fly ash (fly ash microspheres), 720kg of industrial sand (particle size of industrial sand is 0.075-2.36mm, fineness modulus is 1.6, porosity is 37%, water absorption rate is 3%, and silica content is 70%), 350kg of water, 20.6kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent with a water reduction rate greater than 30%), 6kg of nano silica, and 45kg of expanding agent (calcium-magnesium composite expanding agent). In this embodiment, the total adhesive content is 1186 kg (cement + fly ash + nano silica). The water-cement ratio is 0.3; the mortar-mortar ratio is 1.65; and the density of the mortar-aggregate polymer steel pipe concrete is 2560 kg / m³.

[0035] Comparative Example 1 A type of steel-tube concrete, wherein the concrete grade in this embodiment is C30, specifically comprises the following raw materials in parts by weight: Each cubic meter of concrete comprises the following raw materials mixed together: 320kg of cement, 85kg of fly ash (Class F, Grade II fly ash), 770kg of manufactured sand (the particle size of the manufactured sand is 0-4.75mm, and the fineness modulus is 2.9), 1020kg of coarse aggregate, 158kg of water, 8.1kg of high-performance water-reducing agent (water reduction rate greater than 25%), and 45kg of expansion agent. In this embodiment, the total adhesive content is 405 kg (cement + fly ash). The water-cement ratio is 0.39, the concrete density is 2400 kg / m³, the 28-day compressive strength is 43.8 MPa, the 60-day compressive strength is 47.2 MPa, and the material cost per cubic meter of concrete is 403.4 yuan.

[0036] Comparative Example 2 A type of steel-tube concrete, wherein the concrete grade in this embodiment is C60, specifically comprises the following raw materials in parts by weight: Each cubic meter of concrete comprises the following raw materials mixed together: 440kg of cement, 43kg of fly ash (Class F, Grade I fly ash), 38kg of silica fume, 770kg of manufactured sand (manufactured sand with a particle size of 0-4.75mm and a fineness modulus of 3.0), 980kg of coarse aggregate, 152kg of water, 11.2kg of high-performance polycarboxylate superplasticizer (polyester-type polycarboxylate superplasticizer with a water reduction rate greater than 25%), and 48kg of expansion agent; In this embodiment, the total adhesive content is 521 kg (cement + fly ash + silica fume). The water-cement ratio is 0.29, the concrete density is 2445 kg / m³, the 28-day compressive strength is 74.1 MPa, the 60-day compressive strength is 77.9 MPa, and the material cost per cubic meter of concrete is 525.2 yuan.

[0037] To fully demonstrate the superior performance of the paste-aggregate polymer concrete of the present invention and to facilitate performance comparison, the formulation parameters of the above embodiments are preferably summarized in this embodiment: Table 1 is a comparison table of parameter information for the grout-aggregate polymer steel tube concrete formulations of Examples 1-8.

[0038] Regarding the effectiveness verification data: Table 2 is a summary table of the performance tests of the paste-aggregate polymer concrete in Examples 1-8.

[0039] Table 3 is a summary table of parameter information and performance test information for the comparative examples.

[0040] The density of the slurry-aggregate polymerized steel-tube concrete of this invention was also tested (hardened concrete): tapping, ultrasonic testing, and drilling methods were used for cross-verification, and ultrasonic re-examinations were conducted periodically (e.g., 7d, 14d, 28d, 60d, 90d, 120d, 240d, 365d) to confirm that the density of the steel-tube concrete did not deteriorate over time. Specifically, the ultrasonic testing results for the steel-tube concrete formed in Example 2 showed a wave velocity range of 3900~4300m / s, with no instances below 3800m / s, meeting the requirements.

[0041] In the technical solution of this invention, the slurry-aggregate polymerized steel pipe concrete, as the concrete inside the steel pipe, allows for separate preparation of aggregates and slurry. Aggregates can be sourced locally, reducing the waste from repeated transportation of aggregates from the quarry to the mixing plant and then to the construction site. Slurry preparation avoids mixing aggregates; a common slurry mixer can be used to complete slurry preparation and pouring locally, saving many process steps and eliminating the risk of segregation and pipe blockage during pouring. The slurry-aggregate ratio in the slurry-aggregate polymerized steel pipe concrete is changed from the conventional >1 to <1, enhancing the skeletal effect, further limiting the shrinkage of the slurry-aggregate polymerized steel pipe concrete, and reducing the risk of debonding between the steel pipe and concrete, resulting in a lack of synergistic effect. Cementitious materials account for a relatively high proportion of the cost in concrete. Due to the high proportion of aggregates and low slurry usage, slurry-aggregate polymerized steel pipe concrete has lower material costs compared to concrete of the same grade. Combined with the simplified process, its economic efficiency is even higher.

[0042] The above embodiments describe only the basic principles, main features and / or advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and the description of the invention content in the specification are only the principles or specific cases of the present invention. Without departing from the essence of the innovative idea of ​​the present invention, there are various changes and improvements to the innovative solution of the present invention, and all such changes and improvements fall within the scope of protection claimed by the present invention.

Claims

1. A type of grout-aggregate polymerized steel pipe concrete, characterized in that, It includes the following raw materials by volume: 55-57 parts aggregate and 43-45 parts slurry; The slurry-aggregate polymer steel pipe concrete is formed by filling the aggregate piled in the steel pipe with slurry and then curing it. The aggregate is coarse aggregate with a particle size range of 9.5-20 mm, forming a porosity of approximately 41-43% (95% confidence level); or coarse aggregate with a particle size range of 16-31.5 mm, forming a porosity of approximately 40%-42% (95% confidence level). The slurry per cubic meter comprises the following raw materials by weight: Total adhesive material: 800-1200 kg, wherein the total adhesive material includes cement, fly ash and nano-silica; The components include 500-1000 kg of cement, 200-500 kg of fly ash, and 0.4-6 kg of nano-silica. It also includes 700-1000 kg of industrial sand, 350-450 kg of water, 8-24 kg of water-reducing agent, and 30-50 kg of expanding agent; The water-cement ratio of the slurry is 0.30-0.45; The mortar-to-cement ratio of the slurry is 0.8-1.7; The industrial sand has a particle size of 0.075-2.36 mm, a fineness modulus of no more than 2.0, a porosity of 20-40%, a water absorption rate of 0.8-5%, and a silica content of 35-70%.

2. The grout-aggregate polymer steel pipe concrete according to claim 1, characterized in that, When the strength grade of the slurry-aggregate polymerized steel pipe concrete is not greater than C60, the aggregate is coarse aggregate with a particle size of 16-31.5mm, and the ratio of the compressive strength of the parent rock of the coarse aggregate to the design compressive strength of the concrete is not less than 1.5; when the strength grade of the slurry-aggregate polymerized steel pipe concrete is greater than C60, the aggregate is coarse aggregate with a particle size of 9.5-20mm, and the ratio of the compressive strength of the parent rock of the coarse aggregate to the design compressive strength of the concrete is not less than 1.

3.

3. The grout-aggregate polymerized steel pipe concrete according to claim 1, characterized in that, When the strength grade of the mortar-aggregate polymer-reinforced steel pipe concrete is not greater than C40, the mortar-cement ratio is 0.8-1.5, and the silica content of the industrial sand is 35%-50%; when the strength grade of the mortar-aggregate polymer-reinforced steel pipe concrete is greater than C40, the mortar-cement ratio is 1.5-1.7, and the silica content of the industrial sand is 50%-70%, wherein not less than 50% of the industrial sand needs to be finely ground, and the specific surface area of ​​the finely ground industrial sand reaches 100-300 m². 2 / kg.

4. The grout-aggregate polymerized steel pipe concrete according to claim 1, characterized in that, When the strength grade of the slurry-aggregate polymerized steel pipe concrete is not greater than C40, the fly ash is Class F, Grade II fly ash; when the strength grade of the slurry-aggregate polymerized steel pipe concrete is greater than C40, the fly ash is Class F, Grade I fly ash or fly ash microspheres.

5. The grout-aggregate polymerized steel pipe concrete according to claim 1, characterized in that, The slurry per cubic meter also includes 0.08-0.36 kg of retarder, which is a sugar retarder, including at least one of glucose, fructose, and sucrose.

6. The grout-aggregate polymerized steel pipe concrete according to claim 1, characterized in that, Each cubic meter of the slurry also includes 30-50 kg of expanding agent, which is a calcium-magnesium composite expanding agent with early, middle and late time-phase expansion effects.

7. The grout-aggregate polymerized steel tube concrete according to any one of claims 1-6, characterized in that, The initial flow cone time of the slurry shall not exceed 18s, and the 3h flow cone time shall not exceed 35s; the initial truncated cone flowability shall not be less than 390mm, and the 3h truncated cone flowability shall not be less than 340mm. Under a pressure of 0.36 MPa, the water leakage rate is no more than 1%.

8. A construction method for grout-aggregate polymer-reinforced steel pipe concrete according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Adjust the tilt angle of the steel pipe and lay the bottom with grout of the same strength; Step 2: Fill the inclined steel pipe with aggregate, allowing it to slide down and compact under its own weight; Step 3: After the aggregate filling in the steel pipe is completed, restore it to the designed tilt angle or keep the state of Step 1 unchanged, and inject grout from one horizontal end to the other or from bottom to top; alternatively, holes can be opened in the pipe body in the state of Step 1, and grout can be poured directly into the holes. Step 4: Observe whether the grout is filled densely by opening holes in the top of the steel pipe, the pipe body, or setting grout outlet pipes at the pipe ends; Step 5: After filling and compacting, wait for the strength to develop until it meets the design requirements, thus forming grout-aggregate polymer steel pipe concrete.

9. The construction method according to claim 8, characterized in that, In step 1, the steel pipe to be filled with aggregate should be tilted at an angle of 30°-90° to the ground, and a base layer of 8-15cm thick slurry of the same strength should be laid in advance. When the length of the steel pipe to be filled exceeds 30m, holes should be made in the pipe body, and the aggregate should be filled in sections with a section length of no more than 15m. Alternatively, a chute or other method can be used to extend into the pipe to assist in conveying the aggregate, ensuring that the aggregate slippage distance is no more than 15m.

10. The construction method according to claim 8, characterized in that, In step 3, the horizontal pumping distance of the slurry should not exceed 100m and the vertical pumping height difference should not exceed 30m. If these distances are exceeded, pumping should be done in sections, and the pumping pressure should not exceed 2MPa. The opening diameter of the slurry for direct pouring should be 2-5cm.

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