High ductility polymer concrete, preparation method and high ductility polymer concrete prestressed cantilever enclosure pile and construction method

Abstract

The present application relates to the technical field of high ductility concrete, and particularly relates to high ductility polymer concrete, wherein each cubic meter of the high ductility polymer concrete comprises the following components: steel fiber 25-40 kg / m 3 , volcanic ash 200-250 kg / m 3 , metakaolin 200-250 kg / m 3 , alkali activator 25-75 kg / m 3 , fine aggregate 600-700 kg / m 3 , coarse aggregate 1100-1300 kg / m 3 , and water 150-200 kg / m 3 . The present application also discloses a preparation method of the high ductility polymer concrete, a prestressed cantilever enclosure pile with the high ductility polymer concrete and a construction process of the prestressed cantilever enclosure pile. The high ductility polymer concrete is used as the pouring material, and the process is simple, the energy consumption is low, the environmental pollution is small, the early strength is high, and the maintenance age of the pile is greatly shortened. Meanwhile, the prestressed structure is combined to realize the tension and anchoring of the enclosure pile to form an eccentric prestressed pile, so that the enclosure pile can be stable and safe when bearing external load. The prestressed cantilever enclosure pile has the advantages of light weight and high strength, and is suitable for the engineering fields of foundation pit support, bridge foundation and the like under various complex geological conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high ductility concrete, and particularly relates to a high ductility geopolymer concrete, a preparation method and a high ductility geopolymer concrete prestressed cantilever retaining pile and a construction method. BACKGROUND

[0002] During deep foundation pit excavation, retaining piles are used to support and protect the surrounding structures of soil or water, and the design needs to consider various factors, including soil conditions, underground water level, surrounding structure load and construction conditions. During construction, to ensure the safety, reliability and economy of the project, the type, size and arrangement of the retaining piles are particularly important.

[0003] Traditional retaining piles are usually made of reinforced concrete, steel or composite materials, although these materials have high strength and durability and can withstand large water pressure and soil pressure, but they are prone to cracking and breaking when subjected to external forces, and have a long construction period and low construction efficiency.

[0004] In addition, when subjected to large loads or vibration and impact loads, the traditional retaining piles are prone to cracking, the prestressed pile body is prone to deformation, and cannot resist bending and shear force well. SUMMARY

[0005] To solve at least one of the above technical problems, the present application provides a high ductility geopolymer concrete, a preparation method and a prestressed cantilever retaining pile and a construction method thereof, to solve the problems of long construction period, low construction efficiency and poor bending and shear resistance of the prestressed pile body of the traditional retaining piles.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] The present application provides a high ductility geopolymer concrete, each cubic meter of the high ductility geopolymer concrete comprising the following components:

[0008] Steel fiber 25-40 kg / m 3 , volcanic ash 200-250 kg / m 3 , metakaolin 200-250 kg / m 3 , alkali activator 25-75 kg / m 3 , fine aggregate 600-700 kg / m 3 , coarse aggregate 1100-1300 kg / m 3 , water 150-200 kg / m 3 .

[0009] Preferably, the steel fiber adopts a corrugated steel fiber, the length is 25-35mm, the diameter is 0.3-0.5mm, and the length-diameter ratio ranges from 60 to 80; the fine aggregate is natural sand or artificial sand, the particle size ranges from 0.075mm to 4.75mm, and the coarse aggregate is gravel, the particle size ranges from 5mm to 16mm.

[0010] Preferably, the volcanic ash adopts mechanically ground volcanic ash, the specific surface area is 50-100m 2 / g, and the particle size is 10-45um; the metakaolin adopts high-performance metakaolin, the specific surface area is 20-30m 2 / g, and the particle size is 2-10um.

[0011] The alkali activator is a mixture of potassium hydroxide solution and potassium water glass solution, wherein the concentration of the potassium hydroxide solution is 8-12M, the mass is 5-15kg / m 3 , the mass of the potassium water glass solution is 20-60kg / m 3 .

[0012] The second aspect of the present application provides a high-ductility polymer concrete preparation method as described in the first aspect, comprising the following steps:

[0013] S1, the volcanic ash, metakaolin, sand and gravel are weighed in proportion, mixed and stirred, after the stirring is completed, the colors of the coarse aggregate and the fine aggregate should be consistent, and there should be no obvious local aggregation or stratification phenomenon, to obtain a dry mixed mixture A;

[0014] S2, the potassium hydroxide is dissolved in water to prepare a potassium hydroxide solution with a set concentration, the potassium water glass solution is added to the potassium hydroxide solution, and after stirring and uniform mixing, the mixture is cooled to 20-25℃ to obtain a mixture B;

[0015] S3, the steel fiber is uniformly scattered into the mixture A, and the dry stirring is continued until the steel fiber is uniformly distributed in the mixture and there is no obvious aggregation or clumping phenomenon, and the stirring is stopped;

[0016] S4, the mixture B is added to the mixture A in two times, after the first addition, the stirring is continued until the aggregate is uniformly wrapped by the cementitious material slurry, the mixture B is added for the second time, and the stirring is continued to obtain the high-ductility polymer concrete.

[0017] The third aspect of the present application provides a high-ductility polymer concrete prestressed cantilever enclosure pile, comprising a prestressed pile body, the prestressed pile body comprises a steel reinforcement cage, a prestressed assembly arranged on the steel reinforcement cage, and a high-ductility polymer concrete as described in the first aspect or prepared by the high-ductility polymer concrete preparation method as described in the second aspect, and a corbel is arranged at the upper part of the prestressed pile body.

[0018] Preferably, the prestressed assembly comprises:

[0019] A tensioning base plate is arranged on the upper portion of the crown beam.

[0020] A plurality of support plates are fixedly arranged on the inner side of the bottom of the reinforcement cage and are parallel to the cross section of the prestressed pile body.

[0021] A plurality of fixing plates are fixedly arranged on the inner side of the reinforcement cage and are located between the support plates and the tensioning base plate, and the fixing plates are parallel to the support plates.

[0022] A plurality of prestressed steel bars are sequentially arranged through the tensioning base plate, the fixing plate and the support plate along the height direction of the reinforcement cage.

[0023] A plurality of fixing members are arranged for fastening the prestressed steel bars to the support plates and the tensioning base plate.

[0024] Preferably, the tensioning base plate, the fixing plate and the support plate are each provided with concentric through holes for the arrangement of the prestressed steel bars, and the fixing members are fixed to the lower portions of the support plates and the upper portion of the tensioning base plate.

[0025] Preferably, the reinforcement cage comprises a plurality of longitudinally arranged longitudinal steel bars and a plurality of shearing stirrups fixedly arranged around the outer portions of the longitudinal steel bars.

[0026] The fourth aspect of the present application provides a construction method of the high-ductility polymer concrete prestressed cantilever enclosure pile according to the third aspect, and the method comprises the following steps:

[0027] S1', the longitudinal steel bars and the shearing stirrups are fixedly arranged to form the reinforcement cage by binding;

[0028] S2', the fixing plate and the support plate are fixedly arranged at the corresponding positions of the reinforcement cage by welding according to the construction drawing, and the concentricity of the through holes on the fixing plate and the support plate is ensured;

[0029] S3', the prestressed steel bars are sequentially arranged through the support plate and the fixing plate, and the prestressed steel bars are fastened to the support plate by the fixing member, and the prestressed steel bars are provided with reserved holes;

[0030] S4', the reinforcement cage is hoisted to the designated position, the high-ductility polymer concrete is poured into the reinforcement cage, and the mold is removed after regular maintenance;

[0031] S5', the tensioning base plate is fixedly arranged on the upper portion of the crown beam, and the anchoring prestressed steel bars are tensioned;

[0032] S6', the reserved holes of the prestressed steel bars are poured and maintained, and the construction of the high-ductility polymer prestressed cantilever enclosure pile is completed.

[0033] According to the construction method of the high-ductility polymer concrete prestressed cantilever retaining pile of claim 9, the S4' comprises the following steps:

[0034] Preferably, before pouring the high-ductility polymer concrete, the sealing and strength of the formwork are checked to prevent leakage of the polymer slurry, and a release agent is applied to the inner surface of the formwork to prevent adhesion and improve the release quality.

[0035] During pouring, the pouring speed should be controlled to avoid segregation caused by rapid pouring, and the vibrating rod should be inserted vertically with a spacing of 30-50 cm and each vibration time being 5-10 seconds to avoid over-vibration; if pouring is performed in multiple times, a construction joint should be reserved at the stop position of pouring, and the joint treatment should be performed.

[0036] After pouring is completed, the concrete surface should be leveled to avoid shrinkage cracking in the later period, and wet straw bags or plastic film should be immediately covered to keep it wet.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] 1. The high-ductility polymer concrete provided by the present application has the following advantages in mechanical properties: the addition of steel fibers greatly improves the ductility and impact resistance, and can bear tensile force to prevent crack propagation and consume impact energy; the cooperation of the steel fibers, the volcanic ash and the metakaolin further improves the tensile, bending and impact resistance; the volcanic ash and the metakaolin react to generate a gel to fill pores and form a dense microstructure due to the complementary particle size and specific surface area, and the reasonable grading of the fine and coarse aggregates together improves the compressive strength. In terms of durability, the volcanic ash and the metakaolin provide long-term and early strength development, respectively, improve the impermeability and chemical corrosion resistance, and the synergistic effect of the steel fibers and the aggregates also enhances the crack resistance. In terms of working performance, the potassium water glass solution in the alkali activator adjusts the setting time and working performance, and ensures that the volcanic ash and the metakaolin fully react to build a high-ductility and high-strength system with other components, so that the concrete performs well in each stress stage.

[0039] 2.The high-ductility geopolymer concrete prestressed cantilever retaining pile of the present application, by prestressed reinforcement to the retaining pile to exert eccentric prestress, the eccentric prestress can be pre-applied to the compressive stress in the tension area before the prestressed pile body is loaded, which can reduce the tensile stress peak value of the tension area, improve the stress state, and reduce the tensile cracks of the concrete; the generated pre-pressure will form a bending moment in the pile which is opposite to the bending moment direction of the external load, change the stress distribution of the prestressed pile body cross section, improve the bending resistance, reduce the deformation and stress of the beam; it can also adjust the deformation mode of the prestressed pile body, limit the lateral deformation, maintain the stability of the pile-soil interaction system, and enhance the lateral displacement resistance of the prestressed pile body in the foundation pit support in soft soil area; at the same time, by using high-ductility geopolymer concrete pouring, the combination of eccentric prestress and high-ductility concrete can fully exert the mechanical properties of the material, control the deformation, avoid premature cracking, improve the material utilization efficiency and the service life of the retaining pile, and the early strength and fast hardening characteristics of high-ductility geopolymer concrete shorten the construction and maintenance period, and improve the comprehensive performance and stability of the prestressed cantilever retaining pile. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of a high-ductility geopolymer concrete prestressed cantilever retaining pile.

[0041] Figure 2 It is a structural schematic diagram of a steel reinforcement cage in the present application.

[0042] Figure 3 It is a flowchart of a high-ductility geopolymer concrete preparation method.

[0043] Figure 4 It is a flowchart of a high-ductility geopolymer concrete prestressed cantilever retaining pile construction method.

[0044] In the figure: 1, prestressed pile body; 2, high-ductility geopolymer concrete; 3, steel reinforcement cage; 4, shear stirrup; 5, longitudinal reinforcement; 6, prestressed reinforcement; 7, tensioning pad; 8, fixed plate; 9, support plate. DETAILED DESCRIPTION

[0045] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings in the embodiments of the present application. It is obvious that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application.

[0046] The present application provides a high ductility polymer concrete 2 prestressed cantilever retaining pile, which uses high ductility polymer concrete 2 as pouring material, and realizes tension and anchoring of the retaining pile by combining prestressed structure, so that the retaining pile can keep stable and safe when bearing external load. The prestressed cantilever retaining pile has the advantages of light weight, high strength, good durability and the like, and is suitable for engineering fields such as foundation pit support and bridge foundation under various complex geological conditions.

[0047] The structure, construction process of the prestressed cantilever retaining pile, and the high ductility polymer concrete 2 poured in the prestressed cantilever retaining pile and the preparation method thereof will be described in detail below with reference to the drawings.

[0048] Please refer to Figure 1 The present application provides a high ductility polymer concrete 2 prestressed cantilever retaining pile, which uses high ductility polymer concrete 2 as pouring material, and realizes tension and anchoring of the retaining pile by combining prestressed structure, so that the retaining pile can keep stable and safe when bearing external load. The prestressed cantilever retaining pile has the advantages of light weight, high strength, good durability and the like, and is suitable for engineering fields such as foundation pit support and bridge foundation under various complex geological conditions.

[0049] It should be noted that, as Figure 2 The above-mentioned steel reinforcement cage 3 includes a plurality of longitudinally arranged longitudinal steel bars 5 and shear stirrups 4 fixed around the outside of the longitudinal steel bars 5.

[0050] The above-mentioned prestressed assembly includes a tensioning pad 7, a fixed plate 8, a support plate 9 and a prestressed steel bar 6 arranged in the inside of the steel reinforcement cage 3 from top to bottom along the height direction of the steel reinforcement cage 3.

[0051] The above-mentioned tensioning pad 7 is arranged at the upper part of the corbel, the fixed plate 8 is parallel to the cross section of the prestressed pile body 1 and is fixed at the middle part of the steel reinforcement cage 3, and the support plate 9 is parallel to the fixed plate 8 and is fixed at the position close to the bottom of the steel reinforcement cage 3.

[0052] In order to facilitate the arrangement of the prestressed steel bar 6, the above-mentioned tensioning pad 7, fixed plate 8 and support plate 9 are all provided with through holes. The prestressed steel bar 6 passes through the through holes in sequence, so as to connect the above-mentioned tensioning pad 7, fixed plate 8 and support plate 9 in series, and form an anchoring structure after the high ductility polymer concrete 2 is solidified.

[0053] Considering that the above-mentioned through holes need to have a certain concentricity, in actual operation, positioning tools can be used to ensure the concentricity of the through holes, for example, positioning pins are inserted into one of the installed support plates 9, and then the remaining support plates 9 and fixed plates 8 are arranged on the positioning pins in sequence and are fixed at the set positions of the steel reinforcement cage 3. Thus, the concentricity of the through holes can be effectively ensured.

[0054] At the same time, after installation, the concentricity of the perforation can be calibrated by using a total station or a laser range finder, so as to ensure the accuracy of the concentricity.

[0055] In order to facilitate the fixation of the prestressed steel bar 6 and the support plate 9 to form the fixed point of the bottom of the steel bar cage 3. The lower part of the at least one support plate 9 located at the bottom is fixed with the prestressed steel bar 6 and the support plate 9 through the fixing part. The fixing part can be an anchor fixing or a bolt fixing.

[0056] The prestressed cantilever enclosure pile of the high-ductility geopolymer concrete 2 of the application can generate a deformation trend towards the outside of the foundation pit by prestressed steel bar 6 to the enclosure pile, so as to partially offset the deformation trend of the foundation pit towards the inside of the foundation pit. Thus, the stress state of the prestressed pile body 1 of the enclosure pile is effectively improved.

[0057] The second aspect of the application provides a high-ductility geopolymer concrete 2, each cubic meter of the high-ductility geopolymer concrete 2 comprising the following components:

[0058] Steel fiber 25-40 kg / m 3 , volcanic ash 200-250 kg / m 3 , metakaolin 200-250 kg / m 3 , alkali activator 25-75 kg / m 3 , fine aggregate 600-700 kg / m 3 , coarse aggregate 1100-1300 kg / m 3 , water 150-200 kg / m 3 .

[0059] Specifically, the steel fiber described above is corrugated steel fiber, the length is 25-35 mm, the diameter is 0.3-0.5 mm, and the length-diameter ratio is 60-80; the fine aggregate is natural sand or artificial sand, the particle size is 0.075 mm-4.75 mm, and the coarse aggregate is gravel, the particle size is 5 mm-16 mm.

[0060] The volcanic ash is mechanically ground volcanic ash, the specific surface area is 50-100 m 2 / g, and the particle size is 10-45 um; the metakaolin is high-performance metakaolin, the specific surface area is 20-30 m 2 / g, and the particle size is 2-10 um;

[0061] The alkali activator is a mixture of potassium hydroxide solution and potassium water glass solution, wherein the concentration of the potassium hydroxide solution is 8-12 M, the mass is 5-15 kg / m3, and the mass of the potassium water glass solution is 20-60 kg / m3.

[0062] The following analyzes the role of the above components in the high-ductility polymer concrete 2 and the synergistic effect with other components.

[0063] 1. Role and synergistic effect of steel fibers:

[0064] The addition of steel fibers significantly improves the ductility of concrete. They play a role in bridging cracks in the concrete matrix. When the concrete is subjected to tension and cracks, steel fibers can bear the tension and prevent further expansion of the cracks.

[0065] Specifically, the steel fibers in the present invention are of a corrugated type, which at least plays the following roles in the high-ductility polymer concrete 2:

[0066] 1. Enhance anchoring effect

[0067] The surface shape of the corrugated steel fiber enhances the mechanical anchoring effect between it and the concrete matrix. In concrete, when subjected to tension, corrugated steel fibers are not as easy to pull out as smooth-surfaced fibers. For example, ordinary straight steel fibers mainly rely on the friction between the fiber and the concrete to transfer stress when subjected to tension, while corrugated steel fibers, due to their unique corrugated shape, can form multiple anchoring points in the concrete. These anchoring points increase the gripping force between the steel fiber and the concrete, thus more effectively transferring stress and improving the tensile strength of the concrete.

[0068] 2. Improve crack resistance

[0069] When cracks appear in concrete, corrugated steel fibers can better bridge the cracks. The corrugated shape makes the steel fiber have stronger spanning ability at the crack, and can bear larger tensile stress without being pulled apart. In contrast, straight steel fibers may be more prone to failure during crack propagation. Corrugated steel fibers can effectively prevent further expansion of cracks, allowing the width of the concrete cracks to be controlled. In some structures with high crack control requirements, such as thin-walled structures, hydraulic structures, etc., corrugated steel fiber concrete can exhibit good crack resistance and extend the service life of the structure.

[0070] 3. Improve toughness and impact resistance

[0071] Corrugated steel fibers in concrete can absorb energy through their own deformation. When the concrete is subjected to impact load, the corrugated part of the corrugated steel fiber can elastically deform, converting the impact energy into elastic potential energy and then slowly releasing it. This energy absorption and buffering mechanism makes corrugated steel fiber concrete have better toughness and impact resistance.

[0072] 4. Enhance the synergistic working ability of fibers and matrix

[0073] Due to the good anchoring effect between the corrugated steel fiber and the concrete, the steel fiber and the concrete matrix can work better in the stress process of the concrete. The steel fiber can effectively transfer the stress to the surrounding concrete, so that the concrete can fully play its compression performance. At the same time, the tensile performance of the steel fiber is also fully utilized. This synergistic working ability improves the overall performance of the concrete, so that it can exhibit better mechanical properties under complex stress conditions, such as bending, twisting, etc.

[0074] In addition, the content of the steel fiber in the present application is 25-40 kg / m 3 , the length is 25-35 mm, the diameter is 0.3-0.5 mm, and the length-diameter ratio is 60-80.

[0075] It should be noted that the suitable length-diameter ratio and yield of the steel fiber play a crucial role in improving the deformation resistance and impact absorption capacity of the concrete.

[0076] Specifically, a higher length-diameter ratio can enable the steel fiber to span a larger crack width and bear tensile force, preventing the crack from further expanding. This bridging effect can improve the toughness of the concrete to some extent, ensuring that it can maintain a certain load-carrying capacity when subjected to large deformation.

[0077] At the same time, the steel fiber in the concrete can consume the external impact force received by the concrete through deformation and / or friction, thereby absorbing the impact energy and slowing down the process of external force damage to the concrete.

[0078] Of course, the present application selects the above-mentioned content and length-diameter ratio mainly considering that steel fibers with a too large length-diameter ratio are prone to entangle with each other in the concrete, resulting in clumping and poor flowability of the concrete, which makes it difficult for the concrete to uniformly fill in the structural members. Similarly, a too small length-diameter ratio will significantly reduce the above-mentioned load-carrying capacity and absorption capacity.

[0079] In combination with cementitious materials such as volcanic ash and metakaolin, the steel fiber is firmly bonded in the matrix, because the cementitious material provides good adhesion, so that the steel fiber can effectively transfer stress when stressed, thereby improving the tensile, bending and impact resistance of the overall structure.

[0080] 2. Synergistic effect of volcanic ash and metakaolin:

[0081] The volcanic ash adopts mechanical grinding, with a specific surface area of 50-100 m 2 / g, and a particle size of 10-45 um, and the metakaolin has a specific surface area of 20-30 m 2 / g, with a particle size of 2-10um. The pozzolan and metakaolin, as active admixtures, react under the action of alkali activator. The calcium silicate hydrate and calcium alumino-silicate hydrate gels generated by the reaction of pozzolan and alkali activator can fill the pores, improving the strength and density of concrete. Metakaolin is a high-activity material that can quickly react with the alkali activator to generate more calcium alumino-silicate hydrate gel. The slow reaction of pozzolan provides long-term strength development, while the rapid reaction of metakaolin provides early strength. The combination of the two improves the strength and durability of concrete.

[0082] The particle size and specific surface area of the two are different. The relatively coarse particles of pozzolan and the finer particles of metakaolin complement each other, forming a more dense microstructure. This not only improves the compressive strength of concrete, but also improves the durability of concrete to some extent, such as impermeability and chemical resistance. At the same time, this dense structure also provides a better anchoring basis for steel fibers, enhancing the adhesion between steel fibers and the matrix, further improving the overall performance of concrete.

[0083] 3. The role and synergistic effect of alkali activator:

[0084] In the present application, the alkali activator is a mixture of potassium hydroxide solution and potassium water glass solution. The concentration of potassium hydroxide solution is 8-12M, and the mass is 5-15kg / m 3 . The mass of potassium water glass solution is 20-60kg / m 3 .

[0085] Among them, potassium hydroxide provides an alkaline environment to promote the activation of pozzolan and metakaolin, and potassium water glass solution participates in the reaction to generate cementitious materials and adjust the setting time and workability of concrete. The alkali activator formula in the present application ensures the full reaction of pozzolan and metakaolin, making the concrete have good early strength development and late strength stability.

[0086] At the same time, the alkali activator, together with steel fibers, aggregates, etc., forms a concrete system with high ductility and high strength, so that the concrete can maintain good performance at different stress stages.

[0087] 4. The role of aggregates and the synergistic effect with other components:

[0088] The fine aggregate has a particle size of 0.075mm-4.75mm, and the coarse aggregate has a particle size of 5mm-16mm. The fine aggregate fills the voids between the coarse aggregate, and the coarse aggregate acts as the skeleton of concrete to bear pressure. The reasonable gradation of fine aggregate and coarse aggregate fills the pores of concrete, reduces the water-cement ratio, improves the density of concrete, and reduces the porosity, thereby improving the compressive strength and impermeability.

[0089] In addition, under the reinforcing effect of the steel fibers, the interface bonding between the aggregate and the matrix is improved, because the presence of the steel fibers limits the generation and propagation of interface cracks, enabling the aggregate to better play its load-bearing role, while also improving the crack resistance and deformation capacity of the concrete.

[0090] The prestressed cantilever enclosure pile of the present application is further described below in combination with preparation examples, examples and comparative examples.

[0091] Preparation Example 1

[0092] The present preparation example provides a method for preparing a high-ductility polymer concrete, wherein each cubic meter of the high-ductility polymer concrete comprises the following components: steel fibers 25 kg / m 3 , volcanic ash 200 kg / m 3 , metakaolin 200 kg / m 3 , potassium hydroxide solution 20 kg / m 3 , potassium water glass solution 40 kg / m 3 , sand 600 kg / m 3 , crushed stone 1100 kg / m 3 , water 150 kg / m 3 .

[0093] Please refer to Figure 3 , the specific preparation method comprises the following steps:

[0094] S1, the volcanic ash, metakaolin, sand and crushed stone are weighed according to the proportion, mixed and stirred, and after the stirring is completed, the colors of the coarse aggregate and the fine aggregate should be consistent, and there should be no obvious local aggregation or stratification phenomenon, to obtain a dry mixed mixture A.

[0095] It can be understood that the uniformly mixed mixture A can make the volcanic ash, metakaolin, sand and crushed stone uniformly distributed, and because the particle sizes and specific surface areas of the components in this step are different, the relatively coarse particles of the volcanic ash and the relatively fine particles of the metakaolin complement each other, which helps to form a more compact microstructure basis in the dry mixing process, creating conditions for subsequent reactions and performance improvement.

[0096] S2, the potassium hydroxide is dissolved in water to configure a potassium hydroxide solution with a set concentration, the potassium water glass solution is added to the potassium hydroxide solution, and after being uniformly stirred, it is left to cool to 20-25°C to obtain a mixture B.

[0097] Specifically, the uniformly stirred mixture B is conducive to the thorough mixing of the potassium hydroxide and the potassium water glass, ensuring the stable performance of the alkali activator and preparing for the subsequent activation of the activity of the volcanic ash and the metakaolin.

[0098] S3, evenly spread the steel fiber into the mixture A, continue to dry mix until the steel fiber is evenly distributed in the mixture and there is no obvious aggregation or clumping phenomenon, stop stirring.

[0099] It can be understood that the uniformity of the steel fiber in the mixture A is beneficial to its uniform distribution in the concrete, so that the above-mentioned functions of the steel fiber in the concrete, such as preventing crack propagation and absorbing impact energy, can be fully played.

[0100] S4, add mixture B to mixture A twice, after the first addition, stir until the aggregate is evenly wrapped by the cementitious material slurry, add mixture B again, continue to stir, and obtain high ductility polymer concrete 2.

[0101] It can be understood that the mixture A is added to the mixture B twice, the first stirring is beneficial to the activation of the cementitious material by the alkali activator, promotes the preliminary formation of the gel, and enhances the adhesion between the aggregate and the cementitious material. The second stirring can further activate the activity of the cementitious material, the rapid reaction of metakaolin provides early strength, and the slow reaction of the volcanic ash provides long-term strength development, so that the concrete obtains good early strength development and stability of the later strength, and the strength of the concrete is improved. At the same time, the setting time of the concrete is adjusted to ensure that the concrete system has good high ductility and high strength, and can maintain good performance at different stress stages.

[0102] In summary, the high ductility polymer concrete prepared by the preparation method of the embodiment has at least the following advantages:

[0103] In terms of mechanical properties, the addition of steel fiber and its synergistic effect with other components make the concrete have high ductility, high strength, and good tensile, bending and impact resistance; in terms of durability, the volcanic ash, metakaolin and aggregate cooperate with each other to form a dense structure, thereby further improving the compressive strength of the concrete. At the same time, the dense structure also makes the concrete have good impermeability and chemical corrosion resistance.

[0104] Therefore, the concrete prepared by the preparation method is suitable for various complex geological conditions such as foundation pit support and bridge foundation, and is a kind of concrete material with excellent comprehensive performance.

[0105] Preparation Example Two

[0106] It should be noted that the same preparation steps and their effects as in Preparation Example One will not be repeated.

[0107] The preparation example provides a preparation method of high ductility polymer concrete, wherein, different from Preparation Example One, each cubic meter of high ductility polymer concrete includes the following components: 30 kg / m 3 of steel fiber, 210 kg / m3 , metakaolin 210 kg / m 3 , potassium hydroxide solution 25 kg / m 3 , potassium water glass solution 45 kg / m 3 , sand 620 kg / m 3 , crushed stone 1150 kg / m 3 , water 160 kg / m 3 .

[0108] Preparation Example Three

[0109] It should be noted that the same preparation steps as in Preparation Example One and their resulting effects will not be repeated.

[0110] This preparation example provides a method for preparing a high-ductility polymer concrete, wherein, different from Preparation Example One, each cubic meter of the high-ductility polymer concrete comprises the following components: steel fiber 30 kg / m 3 , volcanic ash 225 kg / m 3 , metakaolin 225 kg / m 3 , potassium hydroxide solution 30 kg / m 3 , potassium water glass solution 50 kg / m 3 , sand 630 kg / m 3 , crushed stone 1200 kg / m 3 , water 170 kg / m 3 .

[0111] Preparation Example Four

[0112] It should be noted that the same preparation steps as in Preparation Example One and their resulting effects will not be repeated.

[0113] This preparation example provides a method for preparing a high-ductility polymer concrete, wherein, different from Preparation Example One, each cubic meter of the high-ductility polymer concrete comprises the following components: steel fiber 40 kg / m 3 , volcanic ash 250 kg / m 3 , metakaolin 250 kg / m 3 , potassium hydroxide solution 40 kg / m 3 , potassium water glass solution 60 kg / m 3 , sand 700 kg / m 3 , crushed stone 1300 kg / m 3 , water 200 kg / m 3 .

[0114] Comparative Preparation Example One

[0115] Comparative Preparation Example One provides a method for preparing a high-ductility polymer concrete, different from the above Preparation Example One, wherein the cementitious material used is ordinary Portland cement.

[0116] Comparative Preparation Example Two

[0117] Comparative Preparation Example Two provides a method for preparing a high-ductility geopolymer concrete, which is different from the above Preparation Example One in that the cementitious material used is a commercially available ordinary portland cement.

[0118] Example One

[0119] This example provides a construction process for a high-ductility geopolymer concrete prestressed cantilever retaining pile, wherein the high-ductility geopolymer concrete used in this example is prepared according to Preparation Example One.

[0120] Please refer to Figure 4 , which specifically includes the following steps:

[0121] S1', the longitudinal reinforcement 5 and the shear stirrup 4 are fixed to make a reinforcement cage 3 by binding and fixing.

[0122] It can be understood that the longitudinal reinforcement 5 serves to provide axial bearing capacity, and the shear stirrup 4 is fixed around the outside of the longitudinal reinforcement 5 to enhance the resistance of the reinforcement cage 3 under shearing conditions, so that the reinforcement cage 3 can withstand various loads that may occur during construction and use, and provide reliable skeletal support for the entire retaining pile structure.

[0123] S2', according to the construction drawing, the fixing plate 8 and the support plate 9 are fixed at the corresponding positions of the reinforcement cage 3 by welding, and the concentricity of the perforations on the fixing plate 8 and the support plate 9 is ensured.

[0124] As mentioned above, the concentricity can be ensured by using positioning tools, the purpose of which is to ensure that the prestressed reinforcement 6 can be smoothly threaded, and in the subsequent tensioning and anchoring process, the prestress can be uniformly transmitted, avoiding the problem of stress concentration caused by different concentricity of the perforations, thereby ensuring that the overall structure of the retaining pile is uniformly stressed, and improving the structural strength and durability of the structure.

[0125] S3', the prestressed reinforcement 6 is sequentially threaded through the support plate 9 and the fixing plate 8, and the prestressed reinforcement 6 is fastened with the support plate 9 by the fixing member, and a reserved channel is provided for the prestressed reinforcement 6.

[0126] It can be understood that the reserved channel serves to prepare for the subsequent tensioning and anchoring, which is beneficial to accurately applying prestress to the retaining pile, so that the retaining pile produces the expected deformation trend to offset the deformation trend of the foundation pit.

[0127] S4', the reinforcement cage 3 is hoisted to the designated position, and the high-ductility geopolymer concrete 2 is poured into the reinforcement cage 3, and the formwork is removed after regular maintenance.

[0128] Specifically, before pouring the high ductile polymer concrete 2, the sealing and strength of the formwork are checked to avoid leakage of the polymer slurry; meanwhile, a release agent is applied to the inner surface of the formwork to prevent adhesion and improve the release quality.

[0129] During pouring, the pouring speed should be controlled to avoid rapid pouring leading to segregation; meanwhile, the vibrating rod should be inserted vertically with a spacing of 30-50 cm, and the vibration time for each time should be 5-10 seconds to avoid excessive vibration, which can discharge air bubbles, make the concrete more compact, and improve the bonding force between the concrete and the reinforcement cage 3 and between the components.

[0130] If pouring is performed in multiple times, a construction joint should be reserved at the stopping position of pouring, and joint treatment should be well performed to ensure that the concrete poured in multiple times is connected tightly to form an integral structure, improve the integrity of the concrete structure, prevent quality problems such as cracks, and ensure the structural continuity and stability of the enclosure pile.

[0131] After pouring is completed, the concrete surface should be leveled to avoid shrinkage cracking in the later period; and wet straw bags or plastic film should be immediately covered to keep it wet. A good curing environment is provided for the concrete to keep the proper humidity during the hardening process, prevent the concrete from generating shrinkage cracks due to rapid water loss, ensure the normal development of the strength of the concrete, and improve the durability and crack resistance of the concrete.

[0132] S5', the tensioning pad 7 is fixed to the upper part of the corbel, and the anchoring prestressed steel bar 6 is tensioned.

[0133] S6', the reserved hole of the prestressed steel bar 6 is poured, and curing is performed, and the high-ductile polymer prestressed cantilever enclosure pile construction is completed.

[0134] The prestressed cantilever enclosure pile made by the construction process has the following advantages:

[0135] Firstly, the application of eccentric prestress can apply a compressive stress in the tension zone before the prestressed pile body 1 is loaded. When the foundation pit is supported, the enclosure pile is subjected to lateral pressure of the pit wall soil, and the eccentric prestress can make the tension zone of the prestressed pile body 1 in a compression state before the soil pressure acts. When the external soil pressure acts, the prestressed pile body 1 first offsets the part of the pre-compressive stress, and then generates tensile stress, thereby effectively reducing the tensile stress peak value of the tension zone of the prestressed pile body 1, improving the stress state of the prestressed pile body 1, and reducing the generation of tensile cracks of the concrete.

[0136] Secondly, the pre-stress generated by eccentric pre-stress will form a bending moment inside the pre-stressed pile body 1 which is opposite to the bending moment generated by external load. Taking the cantilever retaining pile in the present application as an example, when lateral earth pressure makes the pre-stressed pile body 1 generate a bending moment outward, the reverse bending moment generated by eccentric pre-stress can partially offset this bending moment. From the principle of mechanics, according to the bending moment-stress relationship in material mechanics, the eccentric pre-stress changes the stress distribution on the cross section of the pre-stressed pile body 1, so that the bending resistance of the pre-stressed pile body 1 when subjected to lateral load is improved. When external load acts, the deformation and stress of the beam will be reduced.

[0137] Thirdly, eccentric pre-stress can adjust the deformation mode of the pre-stressed pile body 1. Specifically, without eccentric pre-stress, the retaining pile may generate large lateral deformation under lateral load, and even may occur overall instability. The presence of eccentric pre-stress makes the pre-stressed pile body 1 be in a relatively stable stress state at the initial stage of loading, which limits the lateral deformation of the pre-stressed pile body 1. After the lateral deformation of the pre-stressed pile body 1 is reduced, the deformation of the surrounding soil will also be reduced accordingly, which can better maintain the stability of the pile-soil interaction system. For example, in the foundation pit support in soft soil area, the stability of the retaining pile is particularly important due to the low bearing capacity of the soil, and the eccentric pre-stress can enhance the ability of the pre-stressed pile body 1 to resist lateral displacement, thereby ensuring the stability of the entire foundation pit support structure.

[0138] Finally, due to the use of high ductile geopolymer concrete 2 pouring, the pre-stressed cantilever retaining pile made has the advantages of high ductile geopolymer concrete 2.

[0139] Specifically, the combination of eccentric pre-stress and high ductility of concrete can more fully exert the mechanical properties of the material. The high ductility of concrete enables the pre-stressed pile body 1 to have a certain deformation capacity during the loading process, and the eccentric pre-stress can control this deformation to some extent, so that the concrete works within a reasonable stress-strain range. In this way, the performance of the concrete is not only avoided from being reduced due to premature cracking, but also the high ductility of the concrete is effectively utilized in resisting deformation and bearing, improving the material utilization efficiency and prolonging the service life of the retaining pile. In addition, the early strength and fast hardening characteristics of the high ductile geopolymer concrete 2 not only improve the early strength of the pre-stressed pile body 1, but also improve the hardness in the later period, which greatly shortens the construction and maintenance period of the retaining pile.

[0140] Example Two

[0141] It should be noted that the same construction process and its effects as in Example One will not be repeated.

[0142] Different from Example One, the concrete poured in this embodiment uses the high ductile geopolymer concrete 2 prepared in Preparation Example Two.

[0143] Example Three

[0144] It should be noted that the construction process and its resulting effects that are the same as Example One will not be repeated.

[0145] Unlike Example One, the concrete cast in this example uses the high-ductility geopolymer concrete 2 prepared in Preparation Example Three.

[0146] Example Four

[0147] It should be noted that the construction process and its resulting effects that are the same as Example One will not be repeated.

[0148] Unlike Example One, the concrete cast in this example uses the high-ductility geopolymer concrete 2 prepared in Preparation Example Four.

[0149] Comparative Example One

[0150] It should be noted that the construction process and its resulting effects that are the same as Example One will not be repeated.

[0151] Unlike Example One, the concrete cast in this example uses the high-ductility geopolymer concrete 2 prepared in Comparative Preparation Example One.

[0152] Comparative Example Two

[0153] It should be noted that the construction process and its resulting effects that are the same as Example One will not be repeated.

[0154] Unlike Example One, the concrete cast in this example uses the high-ductility geopolymer concrete 2 prepared in Comparative Preparation Example Two.

[0155] Through comparative tests, the strength of the prestressed cantilever retaining piles made in the above examples and comparative examples at different time nodes is as follows:

[0156]

[0157] As can be seen from the above table, the retaining piles made in Examples One to Four using metakaolin and volcanic ash as cementitious materials have significantly higher compressive strength and flexural strength at 3 days, 7 days, and 28 days than the retaining piles made in Comparative Examples One and Two; in terms of crack width, the retaining piles made in Examples One to Four are significantly smaller than the retaining piles made in Comparative Examples One and Two.

[0158] In summary, the high ductility geopolymer concrete prepared by the above preparation method has excellent performance, and further, the prepared high ductility geopolymer concrete is used to manufacture the prestressed cantilever retaining pile by the above construction process, so that the prestressed cantilever retaining pile has better compressive performance, bending performance and crack resistance than the ordinary retaining pile.

[0159] The above is the specific embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements, refinements should be considered as the protection scope of the present application.

Claims

1. A method of producing a high ductility polymer concrete, characterized by, The method comprises the following steps: S1, proportionally weigh the volcanic ash, metakaolin, sand and gravel, mix and stir, after the stirring is completed, the colors of the coarse aggregate and the fine aggregate should be consistent, and there should be no obvious local aggregation or stratification phenomenon, to obtain a dry mixed mixture A; S2, dissolve potassium hydroxide in water to configure a potassium hydroxide solution with a set concentration, add a potassium water glass solution to the potassium hydroxide solution, stir uniformly, and then stand and cool to 20-25℃ to obtain a mixture B; S3, uniformly sprinkle the steel fibers into the mixture A, continue to dry stir until the steel fibers are uniformly distributed in the mixture and there is no obvious aggregation or clumping phenomenon, and stop stirring; S4, add the mixture B to the mixture A in two times, after the first addition, stir until the aggregate is uniformly wrapped by the cementitious material slurry, add the mixture B for the second time, and continue to stir to obtain a high ductility polymer concrete (2); Each cubic meter of the high ductility polymer concrete (2) comprises the following components: Steel fibres 25-40 kg / m 3 , volcanic ash 200-250 kg / m 3 , metakaolin 200-250 kg / m 3 , alkali activator 25-75 kg / m 3 , fine aggregate 600-700 kg / m 3 , coarse aggregate 1100-1300 kg / m 3 , water 150-200 kg / m 3 ; The steel fiber is a corrugated steel fiber with a length of 25-35mm, a diameter of 0.3-0.5mm, and a length-diameter ratio in the range of 60-80; the fine aggregate is natural sand or artificial sand with a particle size of 0.075-4.75mm, and the coarse aggregate is gravel with a particle size of 5-16mm; The volcanic ash adopts mechanically ground volcanic ash, with a specific surface area of 50-100 m 2 / g, and a particle size of 10-45 um, and the metakaolin adopts high-performance metakaolin, with a specific surface area of 20-30 m 2 / g, and a particle size of 2-10 um. The alkali activator is a mixture of potassium hydroxide solution and potassium water glass solution, wherein the concentration of the potassium hydroxide solution is 8-12M, the mass is 5-15kg / m 3 , the mass of the potassium water glass solution is 20-60kg / m 3 .

2. A high ductility polymer concrete prestressed cantilever retaining pile characterized by, The prestressed pile body (1) comprises a steel reinforcement cage (3), a prestressed assembly arranged on the steel reinforcement cage (3), and a high ductility polymer concrete (2) prepared by the method of claim 1 and poured in the steel reinforcement cage (3), and a corbel is arranged at the upper portion of the prestressed pile body (1).

3. The high ductility polymer concrete prestressed cantilever retaining pile according to claim 2, wherein, The prestressed assembly comprises: A tensioning base plate (7) arranged at the upper portion of the corbel; A plurality of support plates (9) fixedly arranged on the inner side of the bottom of the steel reinforcement cage (3) and parallel to the cross section of the prestressed pile body (1) A plurality of fixed plates (8) fixedly arranged on the inner side of the steel reinforcement cage (3) and located between the support plates (9) and the tensioning base plate (7), and parallel to the support plates (9); A plurality of prestressed steel bars (6) sequentially penetrating the tensioning base plate (7), the fixed plates (8) and the support plates (9) along the height direction of the steel reinforcement cage (3); A fixing member for fastening the prestressed steel bars (6) with the support plates (9) and the tensioning base plate (7).

4. The high ductility polymer concrete prestressed cantilever retaining pile according to claim 3, wherein, The tensioning base plate (7), the fixed plates (8) and the support plates (9) are all provided with concentric through holes for facilitating the penetration of the prestressed steel bars (6); and the fixing member is fixed to the lower portions of the support plates (9) and the upper portion of the tensioning base plate (7).

5. The high ductility polymer concrete prestressed cantilever retaining pile according to claim 4, wherein, The steel reinforcement cage (3) comprises a plurality of longitudinally arranged longitudinal steel bars (5) and a shear stirrup (4) fixedly arranged around the outside of the longitudinal steel bars (5).

6. A method of constructing a high ductility polymer concrete prestressed cantilever retaining pile as claimed in claim 5, characterized in that, The method comprises the following steps: S1', fix the longitudinal steel bars (5) and the shear stirrups (4) by binding to make the steel reinforcement cage (3); S2', according to the construction drawing, the fixed plate (8) and the support plate (9) are fixed at the corresponding positions of the steel reinforcement cage (3) by welding, and the concentricity of the perforations on the fixed plate (8) and the support plate (9) is ensured; S3', the prestressed steel bar (6) is sequentially penetrated through the support plate (9) and the fixed plate (8), and the prestressed steel bar (6) is fastened with the support plate (9) through the fixing piece, and the prestressed steel bar (6) is reserved; S4', the steel reinforcement cage (3) is hoisted to the designated position, the high ductile polymer concrete (2) is poured into the steel reinforcement cage (3), and the formwork is removed after regular maintenance; S5', the tensioning pad plate (7) is fixed on the upper part of the crown beam, and the anchoring prestressed steel bar (6) is tensioned; S6', the reserved hole of the prestressed steel bar (6) is poured and maintained, and the construction of the high ductility polymer prestressed cantilever enclosure pile is completed.

7. The construction method of the high-ductility polymer concrete prestressed cantilever retaining pile according to claim 6, characterized in that, The S4' comprises the following steps: S41', before pouring the high ductile polymer concrete (2), the sealing and strength of the formwork are checked to avoid leakage of the polymer slurry; at the same time, release agent is coated on the inner surface of the formwork to prevent adhesion and improve the release quality; S42', during pouring, the pouring speed should be controlled to avoid segregation caused by rapid pouring; at the same time, the vibrating rod should be vertically inserted, the interval should be controlled at 30-50 cm, and the vibration time should be 5-10 seconds each time to avoid excessive vibration; If pouring in batches, construction joints should be reserved at the pouring stop position, and joint treatment should be done well; S43', after pouring, the concrete surface should be leveled to avoid shrinkage cracking in the later period; And immediately cover with wet straw bag or plastic film to keep moist.

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