Fiber-reinforced high-strength cement pole and method for manufacturing the same

Abstract

This invention relates to the field of cement technology, specifically to a fiber-reinforced high-strength cement pole and its preparation method. The pole comprises a steel wire skeleton and a conical annular pole body covering its outer circumference. The pole body is formed by centrifugal molding and curing of a cement-based composite material containing interfacially pre-complexed basalt chopped fibers. The interfacially pre-complexed basalt chopped fibers are obtained sequentially through alkaline activation, silane-nano silica treatment, polycarboxylate segment grafting, and calcium ion pre-complexation, and are added to the slurry after the cementitious material is initially moistened and before the aggregate is added. This method improves the dispersibility and interfacial bonding stability of the basalt chopped fibers in a low water-cement ratio cement matrix, thereby enhancing the pole's compressive, tensile, crack, shrinkage, and freeze-thaw resistance.

Description

Technical Field

[0001] This invention relates to the field of cement technology, and in particular to a fiber-reinforced high-strength cement pole and its preparation method. Background Technology

[0002] Adding fibers to cement-based composites is an effective way to improve their tensile strength and inhibit crack development. Basalt fibers, due to their high strength, alkali resistance, and environmental friendliness, have attracted widespread attention in the preparation of fiber-reinforced cement products. Current technologies typically involve directly incorporating untreated chopped basalt fibers into concrete mixtures, or treating them with simple silane coupling agents. However, when unmodified fibers are directly added, they are prone to agglomeration in the cement paste due to electrostatic and van der Waals forces, resulting in uneven dispersion in the matrix and the formation of weak areas. Simultaneously, the weak physical interlocking and insufficient chemical bonding between the smooth fiber surface and the hydrophilic cement hydration products lead to numerous pores and defects in the fiber-matrix interface transition zone (ITZ), becoming a source of stress concentration and microcrack initiation, severely restricting the full realization of fiber bridging, crack prevention, and toughening effects.

[0003] Even with the use of common silane coupling agents, which improves the physical compatibility between fibers and the matrix to some extent, the improvement effect remains limited for prestressed concrete utility poles requiring low water-to-binder ratios, high fluidity, and centrifugal molding. Firstly, simple silane treatment offers limited improvement to the dispersion stability of fibers in low water-to-binder slurry; fibers may still entangle due to increased slurry viscosity, affecting the workability of the concrete and making uniform centrifugal distribution difficult. Secondly, under high-speed centrifugal force, there is a risk of fiber-slurry separation. Interfaces involving simple physical adsorption or weak chemical interaction are prone to degradation under long-term loads and wet-dry, freeze-thaw cycles, making it difficult to guarantee the dimensional stability and durability of the utility pole during long-term service. More importantly, existing technologies often focus on improving a single performance indicator, or only on fiber dispersion, or only on strengthening interfacial bonding. They lack a systematic and comprehensive solution that can simultaneously optimize fiber dispersion, interfacial strengthening, early hydration stimulation, and form a stable chemical-physical dual bond with the cement matrix under complex process conditions. As a result, the prepared utility poles are difficult to achieve synergistic optimization and fundamental improvement in key indicators such as crack resistance, load-bearing capacity, drying shrinkage, and freeze-thaw resistance. Summary of the Invention

[0004] In view of this, the purpose of this invention is to propose a fiber-reinforced high-strength cement pole and its preparation method, in order to solve the problem of how to comprehensively regulate the interface of basalt fiber in prestressed cement poles with low water-cement ratio and centrifugal molding, so as to simultaneously and significantly improve the crack resistance, load-bearing capacity, shrinkage resistance and freeze-thaw durability of the pole while ensuring the workability of the concrete mixture.

[0005] To achieve the above objectives, the present invention provides a fiber-reinforced high-strength cement pole, comprising a partially prestressed steel wire skeleton and a conical annular pole body covering the outer periphery of the partially prestressed steel wire skeleton, wherein the conical annular pole body is formed by centrifugal molding and curing of a cement-based composite material for fiber-reinforced high-strength poles.

[0006] The raw materials for each cubic meter of the cement-based composite material include: 390-450 kg of silicate cement, 40-70 kg of Grade I fly ash, 20-40 kg of silica fume, 620-690 kg of medium sand, 1000-1100 kg of continuously graded crushed stone, 128-142 kg of mixing water, 5-8 kg of polycarboxylate superplasticizer mother liquor for mixing, and interfacial pre-complexed basalt short fibers obtained by interfacial pre-complexing modification of 1.50-2.60 kg of basalt short fiber precursor.

[0007] The interface pre-complexation modification includes sequential alkaline activation, aminosilane-nano silica hydrolysate treatment, polycarboxylic acid segment grafting, and calcium ion pre-complexation; wherein, the polycarboxylic acid segment grafting is performed using a carbodiimide / N-hydroxysuccinimide activation system to couple the carboxyl groups in the polycarboxylic acid water-reducing agent molecules with the aminosilane layer on the surface of the basalt short-cut fibers; the calcium ion pre-complexation is performed by treating the basalt short-cut fibers after polycarboxylic acid segment grafting with a calcium formate aqueous solution;

[0008] The water-cement ratio of the cement-based composite material is 0.25-0.29, the solid content of the polycarboxylate superplasticizer mother liquor used for mixing is 40%, and its solid content is 0.40%-0.65% of the total mass of the cementitious material.

[0009] Preferably, the basalt chopped fibers have a length of 12 mm, a single filament diameter of 13 μm, a tensile strength of not less than 2000 MPa, and an elastic modulus of not less than 80 GPa; the solid content of the polycarboxylate superplasticizer mother liquor is 40%.

[0010] Preferably, the alkaline activation, by mass fraction, comprises: adding 1.50-2.60 parts of basalt chopped fibers to 8-12 parts of a sodium hydroxide aqueous solution with a mass fraction of 0.5%-1.5%, stirring at 300 r / min for 15-30 min at 20-40℃; after treatment, washing with deionized water and drying to obtain surface-activated basalt chopped fibers.

[0011] Preferably, the silane-nano silica hydrolysate treatment, by mass parts, comprises: weighing 8.00-10.00 parts of anhydrous ethanol, 0.90-1.20 parts of deionized water, and 0.015-0.022 parts of glacial acetic acid, mixing them, and adjusting the pH of the solution to 4.3-4.8; adding 0.060-0.120 parts of 3-aminopropyltriethoxysilane, and stirring at 500 r / min for 30 min at 25°C; subsequently adding 0.040-0.120 parts of... A portion of hydrophilic fumed silica was stirred at 800 r / min for 20-25 min to obtain a silane-nano silica hydrolysate. The surface-activated basalt chopped fibers were added to the silane-nano silica hydrolysate and stirred at 300 r / min for 60-120 min at 40-50 °C. After the reaction was completed, the fibers were filtered out, washed with a 70% (v / v) ethanol aqueous solution, and dried to obtain basalt chopped fibers containing a siloxane-nano silica transition layer.

[0012] Preferably, the polycarboxylate superplasticizer grafting, by weight, comprises: weighing 4.00-5.20 parts deionized water, 0.024-0.035 parts sodium acetate, and 0.010-0.015 parts glacial acetic acid to prepare a sodium acetate buffer solution; adding 0.320-0.600 parts of polycarboxylate superplasticizer stock solution, and then adding 0.018-0.036 parts of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.00... 9-0.020 parts of N-hydroxysuccinimide were stirred at 400 r / min for 20 min at 25 °C to obtain a carboxyl-activated solution; the basalt short-cut fibers containing the siloxane-nano silica transition layer were added to the carboxyl-activated solution and stirred at 300 r / min for 90-150 min at 30-40 °C; after the reaction was completed, the fibers were filtered out, washed with deionized water, and dried to obtain carboxyl-siloxane composite grafted basalt short-cut fibers.

[0013] Preferably, the calcium formate pre-complexation, by mass, comprises: weighing 2.50-3.50 parts of deionized water and 0.030-0.080 parts of calcium formate to prepare a calcium formate aqueous solution; adding the carboxyl-siloxane composite grafted basalt short-cut fibers to the calcium formate aqueous solution, stirring at 200 r / min for 30-60 min at 25°C; filtering out the fibers and drying them, controlling the moisture content of the dried fibers to be no higher than 1.0%, to obtain the interface pre-complexed basalt short-cut fibers.

[0014] Preferably, the nano-silica is hydrophilic fumed silica with a specific surface area of ​​200 m². 2 / g; the loss on ignition of the Grade I fly ash is not greater than 5%; the silica content in the silica fume is not less than 90%; the medium sand is river sand with a fineness modulus of 2.6; the continuously graded crushed stone is 5-20mm continuously graded crushed stone.

[0015] This invention also provides a method for preparing fiber-reinforced high-strength cement utility poles, comprising the following steps:

[0016] (1) Preparation of interfacial pre-complexed basalt short-cut fibers;

[0017] (2) Dry mix silicate cement, Class I fly ash and silica fume to obtain a cementitious mixture;

[0018] (3) Add not less than 75% of the total mixing water mass to the cementitious material mixture and stir to initially wet the cementitious material and obtain a preliminary mixing slurry;

[0019] (4) Add the pre-complexed basalt short fiber to the preliminary mixed slurry and stir to disperse the fiber in the slurry; then add medium sand and continuously graded crushed stone and stir; then add the mixture of polycarboxylate superplasticizer mother liquor and the remaining mixing water and continue stirring to obtain a fiber-reinforced high-strength cement-based composite material for poles.

[0020] (5) The cement-based composite material is loaded into a conical annular pole steel mold with a built-in prestressed steel wire skeleton, and centrifugal molding is performed after the mold is closed; after centrifugal molding, static curing, steam curing, demolding and moist curing are performed to obtain the fiber-reinforced high-strength annular concrete pole.

[0021] Preferably, the centrifugation process is as follows: low-speed centrifugation at 80 r / min for 2 min, medium-speed centrifugation at 220 r / min for 4 min, and high-speed centrifugation at 440-480 r / min for 8-9 min.

[0022] Preferably, the static curing time is 120-150 min; the steam curing includes heating at 20℃ / h to 65-75℃ and steam curing at 65-75℃ for 6-7 h; the demolding is carried out after natural cooling to below 40℃; the moisturizing curing is carried out at 20℃ and relative humidity not less than 95% for 28 days.

[0023] In this invention, pre-complexed basalt chopped fiber refers to modified chopped fiber with basalt chopped fiber as the matrix. After activation with alkali solution, a transition layer containing aminosilane and nano-silica is formed on the fiber surface. This is followed by polycarboxylic acid segment grafting and treatment with calcium formate aqueous solution, resulting in a modified chopped fiber surface possessing a siloxane / nano-silica rough active layer, dispersed polycarboxylic acid segments, and calcium ion pre-complexing sites. The pre-complexing does not require all carboxyl groups to be complexed with calcium ions; rather, it means that after washing and drying, detectable calcium and carboxylate binding sites remain on the fiber surface.

[0024] The beneficial effects of this invention are:

[0025] (1) This invention constructs a gradient reinforcement and toughening interface from the fiber matrix to the cement matrix by continuously modifying the interface of basalt fibers through "alkali activation-silane / nano silica hybridization-polycarboxylic acid grafting-calcium formate pre-complexation". As verified by Example 1, compared with Comparative Example 1 which directly uses unmodified fibers, the 28-day compressive strength of the modified utility pole increased from 66.7 MPa to 74.8 MPa (an increase of 12.1%), the 28-day splitting tensile strength increased from 4.88 MPa to 6.24 MPa (an increase of 27.9%), the maximum crack width under cracking moment decreased significantly from 0.096 mm to 0.044 mm (a decrease of 54.2%), and the residual crack width after unloading decreased from 0.019 mm to 0.006 mm (a decrease of 68.4%), which significantly improved the load-bearing capacity and crack control level of the utility pole.

[0026] (2) The interface control strategy of this invention achieves synergistic enhancement of mechanical properties and durability. The introduction of modified fibers optimizes the interfacial structure and effectively suppresses drying shrinkage and moisture migration channels. As shown in Example 1, the 56-day drying shrinkage strain decreased from 426 × 10⁻⁶. -6 Reduced to 314×10 -6 (A decrease of 26.3%). Simultaneously, the dense interfacial transition zone enhanced resistance to freeze-thaw damage; after 150 freeze-thaw cycles, the relative dynamic modulus of elasticity of the concrete pole increased from 87.8% to 94.8%. Comparative data show that omitting or altering any single treatment step (such as not using silane in Comparative Example 2 or incorporating nano-silica bulk phase in Comparative Example 5) leads to a decrease in overall performance, confirming the necessity and superiority of the multi-step synergistic effect of this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0028] Raw material source and specifications: Basalt chopped strands are selected from basalt fiber chopped yarn for cement concrete from Jiangsu Tianlong Basalt Continuous Fiber Co., Ltd., with a length of 12mm, a single filament diameter of 13μm, a breaking strength of not less than 2000MPa, and an elastic modulus of not less than 80GPa; 3-aminopropyltriethoxysilane is selected from SCA-A10E type silane coupling agent from Nanjing Nengde New Material Technology Co., Ltd., CAS No. 919-30-2; polycarboxylate superplasticizer mother liquor is selected from PCA-HP high adaptability polycarboxylate superplasticizer mother liquor from Jiangsu Subote New Material Co., Ltd., with solid dosage calculated based on a measured solid content of 40%; hydrophilic fumed silica is selected from Evonik AEROSIL 200, with a specific surface area of ​​200m². 2 / g; 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, anhydrous ethanol, glacial acetic acid, sodium acetate, sodium hydroxide, and calcium formate were all selected from analytical grade or chemically pure reagents from Sinopharm Chemical Reagent Co., Ltd.; ordinary silicate cement was selected from Conch brand P·O 52.5 cement, conforming to GB 175-2023; Grade I fly ash was selected from commercially available Grade I low-calcium fly ash from power plants, with a loss on ignition of no more than 5%; silica fume was selected from Elken Microsilica 940-U silica fume, with a silica content of no less than 90%; medium sand was selected from river sand with a fineness modulus of 2.6, conforming to GB / T 14684-2022; crushed stone was selected from 5-20mm continuously graded crushed stone from Conch Building Materials; prestressed steel wire was selected from 5mm diameter low-relaxation prestressed concrete steel wire from Tianjin Yinlong Prestressed Materials Co., Ltd.

[0029] All embodiments and comparative examples use the same partially prestressed wire skeleton and the same pole mold. The pole is designed to be 12m long, with a tip diameter of 190mm, a root diameter of 350mm, and a wall thickness of 55mm. The longitudinal tension wires are 5mm diameter low-relaxation prestressed concrete wires, evenly arranged along the annular cross-section. The tensioning control stress of the wires is 70% of their standard tensile strength, and the net concrete cover thickness of the longitudinal tension wires is not less than 15mm. The number of wires, wire arrangement, spiral reinforcement spacing, tensioning regime, mold size, loading amount, centrifugation regime, and curing regime are kept consistent for each group of poles to eliminate the influence of differences in the wire skeleton on the bending moment for bearing capacity testing.

[0030] Example 1:

[0031] Example 1 provides a method for preparing fiber-reinforced high-strength cement utility poles, based on a ratio of 1m... 3 The concrete gauge for the utility pole is prepared.

[0032] Step 1: Weigh 2.00 kg of basalt chopped fibers with a length of 12 mm and add them to 10 kg of a 1% sodium hydroxide aqueous solution. Stir at 300 rpm for 20 min at 30℃. After treatment, wash five times with 5 kg of deionized water each time, until the pH of the final wash solution is 7.4. Then, dry the washed basalt chopped fibers in an 80℃ hot air environment for 120 min to obtain surface-activated basalt chopped fibers. The purpose of this step is to remove weakly bound impurities on the fiber surface and increase the number of silanol sites that can condense with silane hydrolysis products.

[0033] Step 2: Weigh 9.00 kg of anhydrous ethanol, 1.00 kg of deionized water, and 18 g of glacial acetic acid, mix them, and adjust the pH of the solution to 4.6. Add 80 g of 3-aminopropyltriethoxysilane to the solution and stir at 500 r / min for 30 min at 25 °C to ensure complete hydrolysis of the 3-aminopropyltriethoxysilane. Then add 80 g of hydrophilic fumed silica and stir at 800 r / min for 20 min to obtain a silane-nano silica hydrolysate. Add 2.00 kg of surface-activated basalt chopped fibers obtained in Step 1 to the hydrolysate and stir at 300 r / min for 90 min at 45 °C. After the reaction is complete, filter out the fibers, wash them once with 4 kg of 70% ethanol aqueous solution, and then dry them at 90 °C for 90 min to obtain basalt chopped fibers containing a siloxane-nano silica transition layer.

[0034] Step 3: Weigh 4.50 kg of deionized water, 28 g of sodium acetate, and 12 g of glacial acetic acid to prepare a sodium acetate buffer solution with a pH of 5.5; add 450 g of polycarboxylate superplasticizer mother liquor, which contains 180 g of polycarboxylate superplasticizer solids based on a solid content of 40%; then add 24 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 14 g of N-hydroxysuccinimide, and stir at 400 r / min for 20 min at 25 °C to obtain a carboxyl-activated solution; add the basalt short-cut fibers with a siloxane-nano silica transition layer obtained in Step 2 to the carboxyl-activated solution, and stir at 300 r / min for 120 min at 35 °C; after the reaction is complete, filter out the fibers, wash them five times with 10 kg of deionized water (2 kg each time), and then dry them at 65 °C for 180 min to obtain carboxyl-siloxane composite grafted basalt short-cut fibers;

[0035] Step 4: Weigh 3.00 kg of deionized water and 45 g of calcium formate to prepare a 1.5% (w / w) calcium formate aqueous solution; add the carboxyl-siloxane composite grafted basalt short-cut fibers obtained in Step 3 to the calcium formate aqueous solution, and stir at 200 r / min for 45 min at 25℃; after filtering out the fibers, dry them at 60℃ for 120 min, controlling the moisture content of the dried fibers to be no higher than 1.0%, to obtain interfacial pre-complexed basalt short-cut fibers;

[0036] Step 5: Weigh out 420 kg of P·O 52.5 ordinary Portland cement, 55 kg of Grade I fly ash, 30 kg of silica fume, 650 kg of medium sand, 1060 kg of continuously graded crushed stone, 131 kg of mixing water, 6 kg of polycarboxylate superplasticizer mother liquor, and the interfacial pre-complexed basalt short-cut fibers obtained in Step 4. First, dry mix 420 kg of P·O 52.5 ordinary Portland cement, 55 kg of Grade I fly ash, and 30 kg of silica fume for 60 seconds; add 100 kg of mixing water and mix for 90 seconds to form a uniform wet slurry; then add the interfacial pre-complexed basalt short-cut fibers and continue mixing for 120 seconds; then add 650 kg of medium sand and 1060 kg of continuously graded crushed stone and mix for 120 seconds; finally, add the 6 kg of polycarboxylate superplasticizer mother liquor mixed with 31 kg of mixing water and continue mixing for 180 seconds to obtain the utility pole concrete;

[0037] Step six: The concrete for the utility pole obtained in step five is filled into a conical ring-shaped steel mold for the utility pole with an internal prestressed steel wire skeleton. The designed length of the utility pole is 12m, the tip diameter is 190mm, the root diameter is 350mm, and the wall thickness is 55mm. After filling, the mold is closed and centrifuged. The centrifugation regime is 80r / min low speed for 2min, 220r / min medium speed for 4min, and 460r / min high speed for 8min. After centrifugation, the pole is allowed to stand for 120min, and then the temperature is increased to 70℃ at 20℃ / h. It is then steam-cured at 70℃ for 6h. After steam curing, the pole is allowed to cool naturally to below 40℃ before demolding. It is then moist-cured at 20℃ and relative humidity not less than 95% for 28 days to obtain a fiber-reinforced high-strength cement utility pole.

[0038] Example 2:

[0039] Example 2 provides a method for preparing fiber-reinforced high-strength cement utility poles, based on a ratio of 1m... 3 The concrete gauge for the utility pole is prepared.

[0040] Step 1: Weigh 1.60 kg of basalt short-cut fibers with a length of 12 mm, add them to 8 kg of 0.5% sodium hydroxide aqueous solution, and stir at 300 r / min for 15 min at 25℃. After treatment, wash with 20 kg of deionized water five times, 4 kg each time, until the pH of the final washing solution is 7.6. Then place the washed basalt short-cut fibers in an 80℃ hot air environment to dry for 120 min to obtain surface-activated basalt short-cut fibers.

[0041] Step 2: Weigh 8.00 kg of anhydrous ethanol, 0.90 kg of deionized water, and 15 g of glacial acetic acid, mix them, and adjust the pH of the solution to 4.5. Add 60 g of 3-aminopropyltriethoxysilane to the solution and stir at 500 r / min for 30 min at 25 °C. Then add 40 g of hydrophilic fumed silica and stir at 800 r / min for 20 min to obtain a silane-nano silica hydrolysate. Add 1.60 kg of surface-activated basalt chopped fibers obtained in Step 1 to the hydrolysate and stir at 300 r / min for 70 min at 40 °C. After the reaction is complete, filter out the fibers, wash them once with 3 kg of 70% ethanol aqueous solution, and then dry them at 90 °C for 80 min to obtain basalt chopped fibers containing a siloxane-nano silica transition layer.

[0042] Step 3: Weigh 4.00 kg of deionized water, 24 g of sodium acetate, and 10 g of glacial acetic acid to prepare a sodium acetate buffer solution with a pH of 5.4; add 320 g of polycarboxylate superplasticizer mother liquor, which contains 128 g of polycarboxylate superplasticizer solids based on a solid content of 40%; then add 18 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 9 g of N-hydroxysuccinimide, and stir at 400 r / min for 20 min at 25 °C to obtain a carboxyl-activated solution; add the basalt short-cut fibers with a siloxane-nano silica transition layer obtained in Step 2 to the carboxyl-activated solution, and stir at 300 r / min for 100 min at 32 °C; after the reaction is complete, filter out the fibers, wash them five times with 8 kg of deionized water, and then dry them at 65 °C for 180 min to obtain carboxyl-siloxane composite grafted basalt short-cut fibers;

[0043] Step 4: Weigh 2.50 kg of deionized water and 30 g of calcium formate to prepare a 1.2% (w / w) calcium formate aqueous solution; add the carboxyl-siloxane composite grafted basalt short-cut fibers obtained in Step 3 to the calcium formate aqueous solution, and stir at 200 r / min for 35 min at 25 °C; after filtering out the fibers, dry them at 60 °C for 120 min, controlling the moisture content of the dried fibers to be no higher than 1.0%, to obtain interfacial pre-complexed basalt short-cut fibers;

[0044] Step 5: Weigh out 390 kg of P·O 52.5 ordinary Portland cement, 70 kg of Grade I fly ash, 20 kg of silica fume, 690 kg of medium sand, 1000 kg of continuously graded crushed stone, 128 kg of mixing water, 5 kg of polycarboxylate superplasticizer mother liquor, and the interfacial pre-complexed basalt short-cut fibers obtained in Step 4. First, dry mix 390 kg of P·O 52.5 ordinary Portland cement, 70 kg of Grade I fly ash, and 20 kg of silica fume for 60 seconds; add 98 kg of mixing water and mix for 90 seconds; then add the interfacial pre-complexed basalt short-cut fibers and continue mixing for 120 seconds; then add 690 kg of medium sand and 1000 kg of continuously graded crushed stone and mix for 120 seconds; finally, mix 5 kg of polycarboxylate superplasticizer mother liquor with 30 kg of mixing water and add it, and continue mixing for 180 seconds to obtain the utility pole concrete.

[0045] Step six: The concrete for the utility pole obtained in step five is filled into a conical ring-shaped steel mold for the utility pole with an internal prestressed steel wire skeleton. The designed length of the utility pole is 12m, the tip diameter is 190mm, the root diameter is 350mm, and the wall thickness is 55mm. After filling, the mold is closed and centrifuged. The centrifugation regime is 80r / min low speed for 2min, 220r / min medium speed for 4min, and 440r / min high speed for 9min. After centrifugation, the pole is allowed to stand for 120min, and then the temperature is increased to 65℃ at 20℃ / h. It is then steam-cured at 65℃ for 7h. After steam curing, the pole is allowed to cool naturally to below 40℃ before demolding. It is then moist-cured at 20℃ and relative humidity not less than 95% for 28 days to obtain a fiber-reinforced high-strength cement utility pole.

[0046] Example 3:

[0047] Example 3 provides a method for preparing fiber-reinforced high-strength cement utility poles, based on a ratio of 1m... 3 The concrete gauge for the utility pole is prepared.

[0048] Step 1: Weigh 2.60 kg of basalt short-cut fibers with a length of 12 mm, add them to 12 kg of sodium hydroxide aqueous solution with a mass fraction of 1.5%, and stir at 300 r / min for 25 min at 35℃. After treatment, wash with 30 kg of deionized water five times, 6 kg each time, until the pH of the final washing solution is 7.5. Then place the washed basalt short-cut fibers in an 80℃ hot air environment to dry for 150 min to obtain surface-activated basalt short-cut fibers.

[0049] Step 2: Weigh 10.00 kg of anhydrous ethanol, 1.20 kg of deionized water, and 22 g of glacial acetic acid, mix them, and adjust the pH of the solution to 4.7. Add 120 g of 3-aminopropyltriethoxysilane to the solution and stir at 500 r / min for 30 min at 25 °C. Then add 120 g of hydrophilic fumed silica and stir at 800 r / min for 25 min to obtain a silane-nano silica hydrolysate. Add 2.60 kg of surface-activated basalt chopped fibers obtained in Step 1 to the hydrolysate and stir at 300 r / min for 110 min at 50 °C. After the reaction is complete, filter out the fibers, wash them once with 5 kg of 70% ethanol aqueous solution, and then dry them at 90 °C for 100 min to obtain basalt chopped fibers containing a siloxane-nano silica transition layer.

[0050] Step 3: Weigh 5.20 kg of deionized water, 35 g of sodium acetate, and 15 g of glacial acetic acid to prepare a sodium acetate buffer solution with a pH of 5.6; add 600 g of polycarboxylate superplasticizer mother liquor, which contains 240 g of polycarboxylate superplasticizer solids based on a solid content of 40%; then add 36 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 20 g of N-hydroxysuccinimide, and stir at 400 r / min for 20 min at 25 °C to obtain a carboxyl-activated solution; add the basalt short-cut fibers with a siloxane-nano silica transition layer obtained in Step 2 to the carboxyl-activated solution, and stir at 300 r / min for 140 min at 38 °C; after the reaction is complete, filter out the fibers, wash them five times with 12 kg of deionized water, and then dry them at 65 °C for 210 min to obtain carboxyl-siloxane composite grafted basalt short-cut fibers;

[0051] Step 4: Weigh 3.50 kg of deionized water and 80 g of calcium formate to prepare a 2.3% (w / w) calcium formate aqueous solution; add the carboxyl-siloxane composite grafted basalt short-cut fibers obtained in Step 3 to the calcium formate aqueous solution, and stir at 200 r / min for 55 min at 25℃; after filtering out the fibers, dry them at 60℃ for 150 min, and control the moisture content of the dried fibers to be no higher than 1.0%, to obtain interfacial pre-complexed basalt short-cut fibers;

[0052] Step 5: Weigh out 450 kg of P·O 52.5 ordinary Portland cement, 40 kg of Grade I fly ash, 40 kg of silica fume, 620 kg of medium sand, 1100 kg of continuously graded crushed stone, 142 kg of mixing water, 8 kg of polycarboxylate superplasticizer mother liquor, and the interfacial pre-complexed basalt short-cut fibers obtained in Step 4. First, dry mix 450 kg of P·O 52.5 ordinary Portland cement, 40 kg of Grade I fly ash, and 40 kg of silica fume for 60 seconds; add 108 kg of mixing water and mix for 90 seconds; then add the interfacial pre-complexed basalt short-cut fibers and continue mixing for 150 seconds; then add 620 kg of medium sand and 1100 kg of continuously graded crushed stone and mix for 150 seconds; finally, mix 8 kg of polycarboxylate superplasticizer mother liquor with 34 kg of mixing water and add it, and continue mixing for 180 seconds to obtain the utility pole concrete.

[0053] Step six: The concrete for the utility pole obtained in step five is filled into a conical ring-shaped steel mold for the utility pole with an internal prestressed steel wire skeleton. The designed length of the utility pole is 12m, the tip diameter is 190mm, the root diameter is 350mm, and the wall thickness is 55mm. After filling, the mold is closed and centrifuged. The centrifugation regime is 80r / min low speed for 2min, 220r / min medium speed for 4min, and 480r / min high speed for 8min. After centrifugation, the pole is allowed to stand for 150min, and then the temperature is increased to 75℃ at 20℃ / h. It is then steam-cured at 75℃ for 6h. After steam curing, the pole is allowed to cool naturally to below 40℃ before demolding. It is then moist-cured at 20℃ and relative humidity not less than 95% for 28 days to obtain a fiber-reinforced high-strength cement utility pole.

[0054] Example 4:

[0055] Example 4 provides a method for preparing fiber-reinforced high-strength cement utility poles, based on a ratio of 1m... 3 The concrete gauge for the utility pole is prepared.

[0056] Step 1: Weigh 2.20 kg of basalt chopped fibers with a length of 12 mm, add them to 10 kg of sodium hydroxide aqueous solution with a mass fraction of 1.2%, and stir at 300 r / min for 20 min at 40℃. After treatment, wash five times with 25 kg of deionized water until the pH of the final washing solution is 7.3. Then place the washed basalt chopped fibers in an 80℃ hot air environment and dry for 130 min to obtain surface-activated basalt chopped fibers.

[0057] Step 2: Weigh 9.20 kg of anhydrous ethanol, 1.10 kg of deionized water, and 20 g of glacial acetic acid, mix them, and adjust the pH of the solution to 4.4. Add 95 g of 3-aminopropyltriethoxysilane to the solution and stir at 500 r / min for 30 min at 25 °C. Then add 70 g of hydrophilic fumed silica and stir at 800 r / min for 20 min to obtain a silane-nano silica hydrolysate. Add 2.20 kg of surface-activated basalt chopped fibers obtained in Step 1 to the hydrolysate and stir at 300 r / min for 100 min at 45 °C. After the reaction is complete, filter out the fibers, wash them once with 4 kg of 70% ethanol aqueous solution, and then dry them at 90 °C for 90 min to obtain basalt chopped fibers containing a siloxane-nano silica transition layer.

[0058] Step 3: Weigh 4.80 kg of deionized water, 30 g of sodium acetate, and 13 g of glacial acetic acid to prepare a sodium acetate buffer solution with a pH of 5.3; add 500 g of polycarboxylate superplasticizer mother liquor, which contains 200 g of polycarboxylate superplasticizer solids based on a solid content of 40%; then add 28 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 16 g of N-hydroxysuccinimide, and stir at 400 r / min for 20 min at 25 °C to obtain a carboxyl-activated solution; add the basalt short-cut fibers with a siloxane-nano silica transition layer obtained in Step 2 to the carboxyl-activated solution, and stir at 300 r / min for 130 min at 35 °C; after the reaction is complete, filter out the fibers, wash them five times with 10 kg of deionized water, and then dry them at 65 °C for 190 min to obtain carboxyl-siloxane composite grafted basalt short-cut fibers;

[0059] Step 4: Weigh 3.00 kg of deionized water and 55 g of calcium formate to prepare a calcium formate aqueous solution with a mass fraction of 1.8%; add the carboxyl-siloxane composite grafted basalt short-cut fibers obtained in Step 3 to the calcium formate aqueous solution, and stir at 200 r / min for 50 min at 25℃; after filtering out the fibers, dry them at 60℃ for 130 min, and control the moisture content of the dried fibers to be no higher than 1.0%, to obtain interfacial pre-complexed basalt short-cut fibers;

[0060] Step 5: Weigh out 430 kg of P·O 52.5 ordinary Portland cement, 50 kg of Grade I fly ash, 35 kg of silica fume, 640 kg of medium sand, 1050 kg of continuously graded crushed stone, 136 kg of mixing water, 7 kg of polycarboxylate superplasticizer mother liquor, and the interfacial pre-complexed basalt short-cut fibers obtained in Step 4. First, dry mix 430 kg of P·O 52.5 ordinary Portland cement, 50 kg of Grade I fly ash, and 35 kg of silica fume for 60 seconds; add 104 kg of mixing water and mix for 90 seconds; then add the interfacial pre-complexed basalt short-cut fibers and continue mixing for 120 seconds; then add 640 kg of medium sand and 1050 kg of continuously graded crushed stone and mix for 120 seconds; finally, mix 7 kg of polycarboxylate superplasticizer mother liquor with 32 kg of mixing water and add it, and continue mixing for 180 seconds to obtain the utility pole concrete.

[0061] Step six: The concrete for the utility pole obtained in step five is filled into a conical ring-shaped steel mold for the utility pole with an internal prestressed steel wire skeleton. The designed length of the utility pole is 12m, the tip diameter is 190mm, the root diameter is 350mm, and the wall thickness is 55mm. After filling, the mold is closed and centrifuged. The centrifugation regime is 80r / min low speed for 2min, 220r / min medium speed for 4min, and 460r / min high speed for 9min. After centrifugation, the pole is allowed to stand for 130min, and then the temperature is increased to 70℃ at 20℃ / h. It is then steam-cured at 70℃ for 7h. After steam curing, the pole is allowed to cool naturally to below 40℃ before demolding. It is then moist-cured at 20℃ and relative humidity not less than 95% for 28 days to obtain a fiber-reinforced high-strength cement utility pole.

[0062] Example 5:

[0063] Example 5 provides a method for preparing fiber-reinforced high-strength cement utility poles, based on a ratio of 1m... 3 The concrete gauge for the utility pole is prepared.

[0064] Step 1: Weigh 1.90 kg of basalt short-cut fibers with a length of 12 mm, add them to 9 kg of 0.8% sodium hydroxide aqueous solution, and stir at 300 r / min for 25 min at 30℃. After treatment, wash five times with 24 kg of deionized water until the pH of the final wash solution is 7.5. Then place the washed basalt short-cut fibers in an 80℃ hot air environment to dry for 120 min to obtain surface-activated basalt short-cut fibers.

[0065] Step 2: Weigh 8.80 kg of anhydrous ethanol, 1.00 kg of deionized water, and 17 g of glacial acetic acid, mix them, and adjust the pH of the solution to 4.8. Add 75 g of 3-aminopropyltriethoxysilane and stir at 500 r / min for 30 min at 25 °C. Then add 95 g of hydrophilic fumed silica and stir at 800 r / min for 20 min to obtain a silane-nano silica hydrolysate. Add 1.90 kg of surface-activated basalt chopped fibers obtained in Step 1 to the hydrolysate and stir at 300 r / min for 80 min at 48 °C. After the reaction is complete, filter out the fibers, wash them once with 4 kg of 70% ethanol aqueous solution, and then dry them at 90 °C for 90 min to obtain basalt chopped fibers containing a siloxane-nano silica transition layer.

[0066] Step 3: Weigh 4.30 kg of deionized water, 26 g of sodium acetate, and 11 g of glacial acetic acid to prepare a sodium acetate buffer solution with a pH of 5.8; add 420 g of polycarboxylate superplasticizer mother liquor, which contains 168 g of polycarboxylate superplasticizer solids based on a solid content of 40%; then add 22 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 12 g of N-hydroxysuccinimide, and stir at 400 r / min for 20 min at 25 °C to obtain a carboxyl-activated solution; add the basalt short-cut fibers with a siloxane-nano silica transition layer obtained in Step 2 to the carboxyl-activated solution, and stir at 300 r / min for 110 min at 40 °C; after the reaction is complete, filter out the fibers, wash them five times with 9 kg of deionized water, and then dry them at 65 °C for 180 min to obtain carboxyl-siloxane composite grafted basalt short-cut fibers;

[0067] Step 4: Weigh 2.80 kg of deionized water and 40 g of calcium formate to prepare a calcium formate aqueous solution with a mass fraction of 1.4%; add the carboxyl-siloxane composite grafted basalt short-cut fibers obtained in Step 3 to the calcium formate aqueous solution, and stir at 200 r / min for 60 min at 25℃; after filtering out the fibers, dry them at 60℃ for 120 min, and control the moisture content of the dried fibers to be no higher than 1.0%, to obtain interfacial pre-complexed basalt short-cut fibers;

[0068] Step 5: Weigh out 410 kg of P·O 52.5 ordinary Portland cement, 60 kg of Grade I fly ash, 25 kg of silica fume, 670 kg of medium sand, 1030 kg of continuously graded crushed stone, 133 kg of mixing water, 6 kg of polycarboxylate superplasticizer mother liquor, and the interfacial pre-complexed basalt short-cut fibers obtained in Step 4. First, dry mix 410 kg of P·O 52.5 ordinary Portland cement, 60 kg of Grade I fly ash, and 25 kg of silica fume for 60 seconds; add 102 kg of mixing water and mix for 90 seconds; then add the interfacial pre-complexed basalt short-cut fibers and continue mixing for 120 seconds; then add 670 kg of medium sand and 1030 kg of continuously graded crushed stone and mix for 120 seconds; finally, add the 6 kg of polycarboxylate superplasticizer mother liquor mixed with 31 kg of mixing water and continue mixing for 180 seconds to obtain the utility pole concrete.

[0069] Step six: The concrete for the utility pole obtained in step five is filled into a conical ring-shaped steel mold for the utility pole with an internal prestressed steel wire skeleton. The designed length of the utility pole is 12m, the tip diameter is 190mm, the root diameter is 350mm, and the wall thickness is 55mm. After filling, the mold is closed and centrifuged. The centrifugation regime is 80r / min low speed for 2min, 220r / min medium speed for 4min, and 450r / min high speed for 8min. After centrifugation, the pole is allowed to stand for 120min, and then the temperature is increased to 68℃ at 20℃ / h. It is then steam-cured at 68℃ for 7h. After steam curing, the pole is allowed to cool naturally to below 40℃ before demolding. It is then moist-cured at 20℃ and relative humidity not less than 95% for 28 days to obtain a fiber-reinforced high-strength cement utility pole.

[0070] Comparative Example 1:

[0071] The difference from Example 1 is that the surface treatment of the basalt short-cut fibers in steps one to four of Example 1 is not performed. Instead, 2.00 kg of the same batch of basalt short-cut fibers is directly weighed and added in step five of Example 1 after the cementitious material is initially moistened and before the crushed stone is added. The other conditions are the same as in Example 1.

[0072] Comparative Example 2:

[0073] The difference from Example 1 is that in step two of Example 1, 80g of 3-aminopropyltriethoxysilane is not added, and 80g of anhydrous ethanol is used to make up the liquid mass. The amount of hydrophilic fumed silica added, the reaction temperature, the reaction time, and steps three to six in step two are the same as in Example 1. All other conditions are the same as in Example 1.

[0074] Comparative Example 3:

[0075] The difference from Example 1 is that in step three of Example 1, 24g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 14g of N-hydroxysuccinimide are not added. The amount of polycarboxylate superplasticizer mother liquor added, the pH of the sodium acetate buffer, the reaction temperature, and the reaction time remain unchanged, so that the polycarboxylate superplasticizer adheres to the fiber surface only by physical adsorption. The remaining conditions are the same as in Example 1.

[0076] Comparative Example 4:

[0077] The difference from Example 1 is that 80g of hydrophilic fumed silica is not added in step two of Example 1; and to maintain a consistent total mass of silica powder entering the concrete system, the amount of silica fume in step five of Example 1 is adjusted from 30kg to 30.08kg. All other conditions are the same as in Example 1.

[0078] Comparative Example 5:

[0079] The difference from Example 1 is that, in step two of Example 1, 80g of hydrophilic fumed silica is not added. Instead, in step five of Example 1, 80g of hydrophilic fumed silica is added simultaneously with the polycarboxylate superplasticizer mother liquor and the remaining mixing water. All other conditions are the same as in Example 1.

[0080] Comparative Example 6:

[0081] The difference from Example 1 is that the calcium formate pre-complexation treatment in step four of Example 1 is omitted. Instead, 45g of calcium formate is directly added to the polycarboxylate superplasticizer mother liquor and the remaining mixing water added at the end of step five of Example 1. All other conditions are the same as in Example 1.

[0082] Comparative Example 7:

[0083] The difference from Example 1 is that in step five of Example 1, the pre-complexed basalt chopped fibers are not added after the cementitious material is initially moistened and before the crushed stone is added. Instead, they are added after the medium sand and continuously graded crushed stone are added and stirred for 120 seconds. After adding the fibers, stirring is continued for another 120 seconds. Finally, the polycarboxylate superplasticizer mother liquor and the remaining mixing water are added and stirred for 180 seconds. The remaining conditions are the same as in Example 1.

[0084] Sample preparation before performance testing: Examples 1-5 and Comparative Examples 1-7 all prepared concrete pole specimens, standard concrete specimens, modified or unmodified basalt chopped fiber samples, and 12m conical ring-shaped concrete pole samples according to their respective methods. Each group of concrete was mixed in a single batch of at least 0.20m³. 3The cubic specimens used for physical and mechanical properties were 100mm×100mm×100mm in size; the cubic specimens used for splitting tensile strength were 100mm×100mm×100mm in size; the prism specimens used for drying shrinkage were 100mm×100mm×515mm in size; and the prism specimens used for freeze-thaw tests were 100mm×100mm×400mm in size. Standard concrete specimens were cured at 20℃ and a relative humidity of not less than 95% until the specified age. Annular concrete utility poles were prepared according to the centrifugation, steam curing, and subsequent moisture-curing regimes of each embodiment and comparative example, with at least three poles prepared for each group. All test samples were derived from the same batch of concrete or the same batch of fiber-treated products from the corresponding embodiment or comparative example, without changing the raw materials, equipment, curing conditions, or test methods.

[0085] Slump test of concrete mixture: The slump test shall be conducted in accordance with GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixture". Samples of each group of concrete shall be taken within 5 minutes after the final mixing specified in the example or comparative example, with a sample size of not less than 20L. The slump cone and base plate shall be moistened until there is no standing water on the surface. The mixture shall be filled, compacted, and the cone lifted according to standard layers, and the slump of the mixture shall be measured.

[0086] 28-day compressive strength test: The 28-day compressive strength test was conducted according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". Six 100mm×100mm×100mm cube specimens were prepared and tested for each group. After the specimens were formed, they were cured at 20℃ and relative humidity not less than 95% for 28 days. Before the test, the surface water was wiped off and the flatness of the pressure surface was checked. The loading rate was controlled at 0.6MPa / s. The failure load was recorded and the compressive strength was calculated.

[0087] 28-day splitting tensile strength test: The 28-day splitting tensile strength test was conducted according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". Six 100mm×100mm×100mm cube specimens were prepared and tested for each group, and the curing regime was the same as that for the compressive strength specimens. During the test, spacers were placed at the upper and lower stress lines of the specimens, and the loading rate was controlled at 0.05MPa / s. The maximum load when the specimen splits along the stress line was recorded and converted into the splitting tensile strength.

[0088] Bending performance test of ring-shaped concrete utility poles: The bending performance of the utility poles was tested according to GB / T 4623-2014 "Ring-shaped Concrete Utility Poles". Examples 1-5 and Comparative Examples 1-7 all used 12m tapered ring-shaped concrete utility poles aged 28 days, with at least 3 poles per group. Before the test, the pole tip diameter, root diameter, wall thickness, visible cracks, and curing age were recorded. The utility poles were installed using standard support methods and loaded to the crack test moment using a graded loading system. The load was maintained, and the maximum crack width in the tension zone was measured using a crack width observation instrument with a reading accuracy of 0.001mm. The load was then unloaded to zero, and the residual crack width was recorded. Loading was continued to the bearing capacity test moment, and the maximum bearing capacity bending moment was recorded.

[0089] Drying shrinkage performance test: Drying shrinkage test was conducted according to GB / T 50082-2024 "Standard for Test Methods of Long-Term Performance and Durability of Concrete". Three 100mm×100mm×515mm prism specimens were prepared for each group. After molding, the specimens were cured in the mold for 24 hours. After demolding, they were cured at 20℃ and relative humidity not less than 95% for 3 days. Then, they were transferred to a drying environment at 20℃ and 60% relative humidity to test the length change. The length at the time of transfer to the drying environment was taken as the initial length, and the drying shrinkage strain was recorded after 56 days.

[0090] Relative dynamic modulus of elasticity after freeze-thaw cycles: Freeze-thaw cycle tests were conducted according to the rapid freezing method in GB / T 50082-2024 "Standard for Test Methods of Long-Term Performance and Durability of Concrete". Three 100mm×100mm×400mm prism specimens were prepared for each group. After curing for 28 days, the specimens were immersed in water for 4 days to bring them to a saturated state. The minimum temperature for freeze-thaw cycles was controlled at -18℃, and the maximum temperature was controlled at 5℃. The time for each freeze-thaw cycle was controlled at 3-4 hours, and a total of 150 freeze-thaw cycles were carried out. The transverse fundamental frequency of the specimens was measured before freeze-thaw cycles and after 150 freeze-thaw cycles, and the relative dynamic modulus of elasticity was calculated.

[0091] Table 1 Performance Test Results

[0092]

[0093] As shown in Table 1, in Comparative Example 1, only unmodified basalt short-cut fibers were directly added to the concrete of the utility pole. The slump of the mixture was 75 mm, and the 28-day compressive strength and 28-day splitting tensile strength were 66.7 MPa and 4.88 MPa, respectively. The maximum crack width under the cracking test bending moment reached 0.096 mm, and the residual crack width after unloading was 0.019 mm. This indicates that although the unmodified fibers can provide a certain bridging effect, their dispersibility and interfacial bonding stability are still insufficient.

[0094] Comparative Example 2 did not introduce 3-aminopropyltriethoxysilane, Comparative Example 3 did not undergo carboxyl activation grafting, Comparative Example 4 did not introduce hydrophilic fumed silica on the fiber surface, Comparative Example 5 replaced hydrophilic fumed silica with bulk addition, Comparative Example 6 did not undergo calcium formate pre-complexation, and Comparative Example 7 changed the addition sequence of interface pre-complexed basalt chopped fibers. The 28-day splitting tensile strength, crack width, drying shrinkage, and relative dynamic elastic modulus after freeze-thaw of the above comparative examples did not simultaneously reach the level of Example 1, indicating that a single surface treatment, a single bulk addition, or a simple adjustment of the feeding sequence is difficult to simultaneously achieve fiber dispersion, interface reinforcement, and crack control.

[0095] Example 1 at 2.00 kg / m 3 With a low basalt chopped fiber content, continuous treatment involving alkali activation, a silane-nano silica transition layer, polycarboxylate segment grafting, and calcium formate pre-complexation resulted in an increased 28-day compressive strength of 74.8 MPa, a 28-day splitting tensile strength of 6.24 MPa, reduced maximum crack width under the cracking test bending moment and residual crack width after unloading to 0.044 mm and 0.006 mm, respectively, a bearing capacity test bending moment of 91.6 kN·m, and a 56-day drying shrinkage strain of 314 × 10⁻⁶ kN·m. -6 After 150 freeze-thaw cycles, the relative dynamic modulus of elasticity remained at 94.8%. Example 3, due to its high levels of fiber content, silane content, hydrophilic fumed silica content, polycarboxylate grafting content, and calcium formate pre-complexed content, as well as high cement and silica fume content, exhibited the best performance among all performance indicators. Its 28-day compressive strength, 28-day splitting tensile strength, load-bearing capacity test bending moment, and relative dynamic modulus of elasticity after 150 freeze-thaw cycles reached 80.6 MPa, 6.86 MPa, 97.2 kN·m, and 96.3%, respectively. The maximum crack width under the cracking test bending moment, the residual crack width after unloading, and the 56-day drying shrinkage strain decreased to 0.035 mm, 0.004 mm, and 298 × 10⁻⁶ mm, respectively. -6 This demonstrates that the present invention combines a basalt short-cut fiber surface reaction layer, a nano-silica interface filling layer, polycarboxylate dispersed segments, and calcium ion pre-complexation sites, and coordinates the addition of fibers after the initial wetting of the cementitious material with the mixing sequence. This allows the concrete for utility poles to maintain suitable construction fluidity while effectively improving compressive, tensile, crack, shrinkage, and freeze-thaw resistance, showcasing the synergistic enhancement effect of multiple interface control measures.

[0096] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A fiber-reinforced high-strength cement utility pole, characterized in that, It includes a partially prestressed steel wire skeleton and a conical ring rod covering the outer periphery of the partially prestressed steel wire skeleton. The conical ring rod is formed by centrifugation and curing of a fiber-reinforced high-strength cement-based composite material for electric poles. The raw materials for each cubic meter of the cement-based composite material include: 390-450 kg of silicate cement, 40-70 kg of Grade I fly ash, 20-40 kg of silica fume, 620-690 kg of medium sand, 1000-1100 kg of continuously graded crushed stone, 128-142 kg of mixing water, 5-8 kg of polycarboxylate superplasticizer mother liquor for mixing, and interfacial pre-complexed basalt short fibers obtained by interfacial pre-complexing modification of 1.50-2.60 kg of basalt short fiber precursor. The water-cement ratio of the cement-based composite material is 0.25-0.29, and the solid content of the polycarboxylate superplasticizer mother liquor used for mixing is 40%, with its solid content being 0.40%-0.65% of the total mass of the cementitious materials. The interface pre-complexation modification includes sequential alkaline activation, aminosilane-nano silica hydrolysate treatment, polycarboxylic acid segment grafting, and calcium ion pre-complexation; wherein, the polycarboxylic acid segment grafting is performed using a carbodiimide / N-hydroxysuccinimide activation system to couple the carboxyl groups in the polycarboxylic acid water-reducing agent molecules with the aminosilane layer on the surface of the basalt short fiber; the calcium ion pre-complexation is performed by treating the basalt short fiber after polycarboxylic acid segment grafting with a calcium formate aqueous solution.

2. The fiber-reinforced high-strength cement utility pole according to claim 1, characterized in that, The basalt short-cut fibers have a length of 12 mm, a single filament diameter of 13 μm, a breaking strength of not less than 2000 MPa, and an elastic modulus of not less than 80 GPa; the solid content of the polycarboxylate superplasticizer mother liquor is 40%.

3. The fiber-reinforced high-strength cement utility pole according to claim 1, characterized in that, The alkaline activation, by mass fraction, includes: adding 1.50-2.60 parts of basalt chopped fibers to 8-12 parts of a sodium hydroxide aqueous solution with a mass fraction of 0.5%-1.5%, stirring at 300 r / min for 15-30 min at 20-40℃; washing with deionized water and drying after treatment to obtain surface-activated basalt chopped fibers.

4. The fiber-reinforced high-strength cement utility pole according to claim 3, characterized in that, The silane-nano silica hydrolysate treatment, by mass parts, comprises: weighing 8.00-10.00 parts anhydrous ethanol, 0.90-1.20 parts deionized water, and 0.015-0.022 parts glacial acetic acid, mixing them, and adjusting the pH of the solution to 4.3-4.8; adding 0.060-0.120 parts 3-aminopropyltriethoxysilane, and stirring at 500 r / min for 30 min at 25°C; subsequently adding 0.040-0.120 parts of... Aqueous fumed silica was stirred at 800 r / min for 20-25 min to obtain a silane-nano silica hydrolysate. The surface-activated basalt chopped fibers were added to the silane-nano silica hydrolysate and stirred at 300 r / min for 60-120 min at 40-50 °C. After the reaction was completed, the fibers were filtered out, washed with a 70% (v / v) ethanol aqueous solution, and dried to obtain basalt chopped fibers containing a siloxane-nano silica transition layer.

5. The fiber-reinforced high-strength cement utility pole according to claim 4, characterized in that, The polycarboxylate superplasticizer grafting, by weight, comprises: weighing 4.00-5.20 parts deionized water, 0.024-0.035 parts sodium acetate, and 0.010-0.015 parts glacial acetic acid to prepare a sodium acetate buffer solution; adding 0.320-0.600 parts of polycarboxylate superplasticizer stock solution, and then adding 0.018-0.036 parts of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.009- 0.020 parts of N-hydroxysuccinimide were stirred at 400 r / min for 20 min at 25 °C to obtain a carboxyl-activated solution; the basalt short-cut fibers containing the siloxane-nano silica transition layer were added to the carboxyl-activated solution and stirred at 300 r / min for 90-150 min at 30-40 °C; after the reaction was completed, the fibers were filtered out, washed with deionized water, and dried to obtain carboxyl-siloxane composite grafted basalt short-cut fibers.

6. The fiber-reinforced high-strength cement utility pole according to claim 5, characterized in that, The calcium formate pre-complexing, by mass fraction, comprises: weighing 2.50-3.50 parts of deionized water and 0.030-0.080 parts of calcium formate to prepare a calcium formate aqueous solution; adding the carboxyl-siloxane composite grafted basalt short-cut fibers to the calcium formate aqueous solution, stirring at 200 r / min for 30-60 min at 25°C; filtering out the fibers and drying them, controlling the moisture content of the dried fibers to be no higher than 1.0%, to obtain the interface pre-complexed basalt short-cut fibers.

7. The fiber-reinforced high-strength cement utility pole according to any one of claims 1-6, characterized in that, The nano-silica is hydrophilic fumed silica with a specific surface area of ​​200 m². 2 / g; the loss on ignition of the Grade I fly ash is not greater than 5%; the silica content in the silica fume is not less than 90%; the medium sand is river sand with a fineness modulus of 2.6; the continuously graded crushed stone is 5-20mm continuously graded crushed stone.

8. A method for preparing a fiber-reinforced high-strength cement utility pole according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Preparation of interfacial pre-complexed basalt short-cut fibers; (2) Dry mix silicate cement, Class I fly ash and silica fume to obtain a cementitious mixture; (3) Add not less than 75% of the total mixing water mass to the cementitious material mixture and stir to initially wet the cementitious material and obtain a preliminary mixing slurry; (4) Add the pre-complexed basalt short fiber to the preliminary mixed slurry and stir to disperse the fiber in the slurry; then add medium sand and continuously graded crushed stone and stir; then add the mixture of polycarboxylate superplasticizer mother liquor and the remaining mixing water and continue stirring to obtain a fiber-reinforced high-strength cement-based composite material for poles. (5) The cement-based composite material is loaded into a conical annular pole steel mold with a built-in prestressed steel wire skeleton, and centrifugal molding is performed after the mold is closed; after centrifugal molding, static curing, steam curing, demolding and moist curing are performed to obtain the fiber-reinforced high-strength annular concrete pole.

9. The method for preparing fiber-reinforced high-strength cement utility poles according to claim 8, characterized in that, The centrifugation process is as follows: low speed centrifugation at 80 r / min for 2 min, medium speed centrifugation at 220 r / min for 4 min, and high speed centrifugation at 440-480 r / min for 8-9 min.

10. The method for preparing fiber-reinforced high-strength cement utility poles according to claim 8, characterized in that, The static curing time is 120-150 minutes; the steam curing includes heating at 20℃ / h to 65-75℃ and steam curing at 65-75℃ for 6-7 hours; the demolding is carried out after the temperature naturally drops to below 40℃; the moisturizing curing is carried out at 20℃ and relative humidity not lower than 95% for 28 days.

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