Anti-freeze and freeze-thaw resistant high volume bundle basalt fiber reinforced concrete

Abstract

The application discloses an anti-freezing and thawing high-mixing-content bundle basalt fiber reinforced concrete and belongs to the technical field of concrete processing. The application is used for solving the technical problems of poor anti-freezing performance of the prior art concrete and further improvement of the mixing content of the basalt fiber in the concrete, and the anti-freezing and thawing high-mixing-content bundle basalt fiber reinforced concrete comprises the following components in parts by weight: coarse aggregate 70-78 parts, fine aggregate 30-35 parts, composite cement 25-30 parts, additive 0.2-0.3 parts, bundle reinforcing fiber 0.8-1.2 parts and water 15-20 parts. The application greatly improves the mixing content of the basalt fiber in the concrete by reinforcing and modifying the basalt fiber, and effectively enhances the mechanical properties and the anti-freezing and thawing performance of the concrete test piece by optimizing the particle size ratio of the coarse aggregate and the composite cement and the mutual cooperation of the bundle reinforcing fiber.

Description

Technical Field

[0001] This invention relates to the field of concrete processing technology, specifically to a freeze-thaw resistant, high-content bundled basalt fiber reinforced concrete. Background Technology

[0002] In recent years, with the continuous development of construction projects and infrastructure development, the performance requirements for concrete materials have become increasingly stringent. Most parts of the country experience cold climates, with extreme low temperatures in winter, making the freeze-thaw resistance of concrete particularly crucial. The pore water within concrete undergoes a two-phase cycle of freezing in winter and thawing in spring with periodic temperature changes, subjecting it to varying degrees of freeze-thaw damage and even destruction. Traditional concrete is highly susceptible to micro-cracks, surface spalling, and premature failure under freeze-thaw cycles, reducing its durability and service life. Basalt fiber is a novel fiber material that, when incorporated into concrete, can effectively improve its crack resistance, slow down the decline in concrete strength, and thus enhance its freeze-thaw resistance.

[0003] In existing technologies, basalt fibers have a smooth surface and poor adhesion to the cement matrix, resulting in poor dispersibility in concrete mixes. Increased fiber content easily leads to fiber clumping. Furthermore, as the amount of basalt fibers increases, their water absorption in concrete strengthens, making the concrete more viscous and difficult to form a uniform paste, thus weakening the reinforcing effect of the fibers. Additionally, existing fiber-reinforced concretes have a high content of small-sized aggregates, resulting in a large specific surface area. During freeze-thaw cycles, the volume expansion of the aggregates generates stress, causing cracking and damage to the concrete specimens. Therefore, the freeze-thaw resistance of the concrete specimens needs further improvement.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a high-dosage bundled basalt fiber reinforced concrete with freeze-thaw resistance, which solves the technical problems in the prior art where the freeze-thaw resistance of concrete needs to be further improved, and at the same time, when the basalt fiber dosage is increased, the fibers tend to agglomerate in the concrete, making the concrete viscous and difficult to form a uniform paste, thus preventing the fiber from effectively enhancing the concrete.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A freeze-thaw resistant high-dosage bundled basalt fiber reinforced concrete comprises the following components by weight: 70-78 parts coarse aggregate, 30-35 parts fine aggregate, 25-30 parts composite cement, 0.2-0.3 parts admixture, 0.8-1.2 parts bundled reinforcing fiber, and 15-20 parts water;

[0008] The composite cement is composed of slag, fly ash and silicate cement in a weight ratio of 3:1:6-7. The slag is Yangtze S95 mineral powder with a strength activity index of 106%; the fly ash is Class I F fly ash with a strength activity index of 73%; and the silicate cement is grade P.II 52.5.

[0009] Furthermore, the coarse aggregate is composed of small stones and medium stones mixed in a weight ratio of 1:4, wherein the small stone particle size is 5-20mm and the medium stone particle size is 16-31.5mm; the fine aggregate is river sand with a fineness modulus of 2.6; and the admixture is polycarboxylate superplasticizer with a water reduction rate of 19.4%.

[0010] Furthermore, the bundled reinforcing fibers are obtained by the following steps:

[0011] A1. Place the bundled basalt fibers in a calcination furnace at a temperature of 400-500℃ and calcinate for 3-5 hours. After the temperature of the calcination furnace is reduced to room temperature, wash with purified water and transfer to a drying oven at a temperature of 70-80℃ to dry to constant weight to obtain calcined fibers.

[0012] A2. Add the calcined fiber and activation solution to a beaker and stir. Raise the temperature of the activation solution to 65-75℃ and keep it warm for 3-5 hours. The activated fiber is then obtained through post-treatment.

[0013] A3. Add the activated fiber, reinforcing modifier and anhydrous ethanol to a three-necked flask, stir for 20-30 minutes, raise the temperature of the three-necked flask to 60-70℃, add the catalyst dropwise to the three-necked flask, and after the addition is complete, keep the reaction at the temperature for 4-6 hours. The post-treatment yields bundled reinforcing fibers.

[0014] Furthermore, the density of the bundled basalt fibers in step A1 is 2.6 g / cm³. 3 The length is 17-19 mm and the diameter is 0.2-0.8 mm; the activation solution in step A2 is composed of 7 mol / L sulfuric acid, 8 wt% hydrogen peroxide and 5 mol / L hydrochloric acid in a volume ratio of 10:2:3. The post-treatment operation includes: after the reaction is completed, the beaker temperature is reduced to room temperature, filtered, the filter cake is washed with purified water until neutral, and then the filter cake is transferred to a drying oven at a temperature of 70-80℃ and dried to constant weight to obtain activated fibers.

[0015] Furthermore, in step A3, the ratio of activated fiber, reinforcing modifier, anhydrous ethanol, and catalyst is 3g:2g:20mL:8mL, and the catalyst is a 5wt% sodium hydroxide solution. The post-treatment operation includes: after the reaction is complete, filtration is performed, the filter cake is washed three times with purified water and anhydrous ethanol respectively, and then dried. The filter cake is transferred to a drying oven at a temperature of 70-80℃ and dried to constant weight to obtain bundled reinforcing fibers.

[0016] Furthermore, the reinforcing modifier is obtained by the following steps:

[0017] B1. Add polyethylene glycol monomethyl ether, dichloromethane and potassium carbonate to a three-necked flask, heat and stir until the system is dissolved, raise the temperature of the three-necked flask to the point where the system is slightly refluxed, add thionyl chloride solution dropwise to the three-necked flask, and after the addition is complete, keep the reaction at the temperature for 20-22 hours, and then process to obtain chlorinated polyethylene glycol monomethyl ether.

[0018] The synthesis reaction principle of chlorinated polyethylene glycol monomethyl ether is as follows:

[0019]

[0020] B2. Chlorinated polyethylene glycol monomethyl ether and acetonitrile were added to a three-necked flask under nitrogen and light protection. The mixture was heated and stirred until dissolved. Potassium carbonate and potassium iodide were added to the three-necked flask. The temperature of the three-necked flask was raised to a point where the system was under slight reflux. Ethanolamine was added dropwise to the three-necked flask. After the addition was complete, the reaction was maintained at this temperature for 20-22 hours. The modified polyethylene glycol monomethyl ether was obtained after post-treatment.

[0021] The synthesis reaction principle of modified polyethylene glycol monomethyl ether is as follows:

[0022]

[0023] B3. Add modified polyethylene glycol monomethyl ether and acetonitrile to a three-necked flask under nitrogen protection and stir. Add propyltriethoxysilane isocyanate solution dropwise to the three-necked flask. After the addition is complete, raise the temperature of the three-necked flask to 50-60℃ and keep it at that temperature for 3-5 hours. The post-treatment yields the reinforcing modifier.

[0024] The synthesis reaction principle of the reinforcing modifier is as follows:

[0025]

[0026] Further, in step B1, the polyethylene glycol monomethyl ether is polyethylene glycol monomethyl ether 500, and the ratio of polyethylene glycol monomethyl ether, dichloromethane, potassium carbonate, and thionyl chloride solution is 50g:500mL:25g:20g. The thionyl chloride solution is composed of thionyl chloride and dichloromethane in a weight ratio of 1:4. The post-treatment operation includes: after the reaction is complete, the temperature of the three-necked flask is lowered to room temperature, the mixture is filtered, the filtrate is transferred to a rotary evaporator, the water bath temperature is set to 40°C, and the solvent is removed by vacuum evaporation to obtain chlorinated polyethylene glycol monomethyl ether.

[0027] Furthermore, in step B2, the ratio of chlorinated polyethylene glycol monomethyl ether, acetonitrile, potassium carbonate, potassium iodide, and ethanolamine is 53g:150mL:25g:1g:3g. The post-treatment operation includes: after the reaction is complete, the temperature of the three-necked flask is lowered to room temperature, the mixture is filtered, the filtrate is transferred to a rotary evaporator, the water bath temperature is set to 55°C, the solvent is removed by vacuum distillation, toluene is added to the rotary evaporator, and after mixing evenly, the water bath temperature is raised to 90°C, and the mixture is distilled under reduced pressure until no liquid flows out, thus obtaining modified polyethylene glycol monomethyl ether.

[0028] Furthermore, in step B3, the ratio of modified polyethylene glycol monomethyl ether, acetonitrile, and propyltriethoxysilane isocyanate solution is 21g:200mL:20g. The propyltriethoxysilane isocyanate solution is composed of propyltriethoxysilane and acetonitrile in a weight ratio of 1:3. The post-treatment operation includes: after the reaction is complete, raising the temperature of the three-necked flask to 65-75℃, removing the solvent under reduced pressure, and obtaining the reinforcing modifier.

[0029] The present invention has the following beneficial effects:

[0030] 1. The basalt fiber reinforced antifreeze concrete of the present invention is prepared by selecting relatively large-sized small and medium-sized stones to form coarse aggregate, which is then combined with fine aggregate, composite cement, and bundled reinforcing fibers. Larger aggregates have smaller surface areas and lower water absorption, resulting in concrete with lower thermal conductivity and lower moisture content. Furthermore, larger aggregates may exhibit better volume stability, mitigating temperature changes in concrete specimens under rapid temperature fluctuations and reducing stress caused by volume expansion during freeze-thaw cycles, thereby improving the antifreeze performance of the concrete specimens. The concrete is further enhanced by using slag, fly ash, and silicates as the binders. The appropriate mix proportions utilize admixtures such as fly ash and slag to fill the fine pores in concrete. Some components in fly ash and slag can react with unreacted minerals in cement to form a cementitious substance that fills the voids in the concrete, improving its density and uniformity. This results in a finer pore structure, slowing down water penetration and migration, reducing water-induced damage during freeze-thaw cycles, reducing pore size and interconnections, and decreasing the rate of water penetration in concrete, thereby improving its freeze-thaw resistance. Furthermore, materials such as slag can slow down or inhibit alkali-aggregate reaction, thus improving the durability and freeze-thaw resistance of concrete.

[0031] 2. The basalt fiber reinforced antifreeze concrete of the present invention, by adding bundled reinforcing fibers, forms a three-dimensional random distribution of fibers within the concrete, creating a reinforcing structure. This effectively controls shrinkage cracks caused by internal stress due to shrinkage during the hardening process, improving the compressive strength, splitting tensile strength, and overall performance of the concrete. The present invention selects large-diameter hinged basalt fibers as raw materials. High-temperature calcination removes the protective coating on the surface of the basalt fibers. Heating with an activation liquid removes some oxides or other impurities from the fiber surface, increasing the surface area of ​​the fibers and forming an active substance, such as silicate cementitious materials and oxygen-containing active groups, on the surface of the basalt fibers. These active substances promote the hydration reaction of cement in the concrete, improving the strength and durability of the concrete. Reinforcing modifiers are used to modify the activated fibers, repairing surface defects and damage, improving the surface lubrication performance of the bundled reinforcing fibers, reducing the frictional resistance between the bundled reinforcing fibers and concrete particles, and increasing the dosage of bundled reinforcing fibers, thereby improving the mechanical properties and antifreeze performance of the concrete material.

[0032] 3. The modifier of the present invention is prepared by a nucleophilic substitution reaction between polyethylene glycol monomethyl ether 500 and sulfoxide dichloride. Sulfoxide dichloride, acting as a nucleophile, attacks the electron cloud of the hydroxyl group on polyethylene glycol monomethyl ether 500 with its chloride ions, removing the negative charge from the oxygen atom and forming a chloride-substituted product. The chlorinated polyethylene glycol monomethyl ether then undergoes a nucleophilic substitution reaction with ethanolamine. The amino group (NH2) in the ethanolamine attacks the chloride ions in the chlorinated polyethylene glycol monomethyl ether, replacing them to obtain modified polyethylene glycol monomethyl ether. The hydroxyl group on the modified polyethylene glycol monomethyl ether undergoes a condensation reaction with propyltriethoxysilane isocyanate to obtain the reinforcing modifier. The siloxane bond on the reinforcing modifier molecule hydrolyzes in an alkaline environment to generate silanol groups, which can react with the active oxygen-containing functional groups on the activated fiber surface. The group reaction forms a chemical modification on the surface of the activated fibers, which can effectively address surface defects and damage to the activated fibers. Furthermore, the long chains of polyethylene glycol modified on the surface of the bundled reinforcing fibers have good hydrophilic properties, which can mix rapidly with water and form a uniform liquid film on its surface. This helps to promote the uniform dispersion of the bundled reinforcing fibers in cement concrete, reduce the frictional resistance between the bundled reinforcing fibers and concrete particles, improve the fluidity of concrete, and thus enhance its reinforcing effect in concrete. The introduction of bundled reinforcing fibers can improve the pore structure of concrete, reduce the condensation and expansion of water in the pores, thereby slowing down the damage caused by freeze-thaw cycles, effectively controlling the propagation of cracks in concrete, preventing the propagation of microcracks caused by freeze-thaw cycles, and improving the crack resistance of concrete. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing bundled reinforcing fibers for freeze-thaw resistant, high-dosage bundled basalt fiber-reinforced concrete, comprising the following steps:

[0036] S1. Mix thionyl chloride and dichloromethane at a weight ratio of 1:4 to obtain a thionyl chloride solution for later use.

[0037] Weigh out 500g of polyethylene glycol monomethyl ether, 500mL of dichloromethane, and 25g of potassium carbonate and add them to a three-necked flask. Stir the mixture and raise the temperature of the three-necked flask to a state of slight reflux. Add 20g of thionyl chloride solution dropwise to the three-necked flask. After the addition is complete, keep the mixture at this temperature for 20 hours. Then, lower the temperature of the three-necked flask to room temperature, filter the mixture, and transfer the filtrate to a rotary evaporator. Set the water bath temperature to 40℃ and remove the solvent under reduced pressure to obtain chlorinated polyethylene glycol monomethyl ether.

[0038] S2. Weigh 53g of chlorinated polyethylene glycol monomethyl ether and 150mL of acetonitrile into a three-necked flask protected by nitrogen and light. Heat and stir until the system dissolves. Add 25g of potassium carbonate and 1g of potassium iodide to the three-necked flask. Raise the temperature of the three-necked flask to allow the system to reflux slightly. Add 3g of ethanolamine dropwise to the three-necked flask. After the addition is complete, keep the reaction at this temperature for 20 hours. Lower the temperature of the three-necked flask to room temperature, filter, and transfer the filtrate to a rotary evaporator. Set the water bath temperature to 55℃ and remove the solvent under reduced pressure. Add 50g of toluene to the rotary evaporator and mix thoroughly. Raise the water bath temperature to 90℃ and distill under reduced pressure until no liquid flows out, obtaining modified polyethylene glycol monomethyl ether.

[0039] S3. Mix propyltriethoxysilane isocyanate and acetonitrile at a weight ratio of 1:3 to obtain a propyltriethoxysilane isocyanate solution for later use.

[0040] Weigh 42g of modified polyethylene glycol monomethyl ether and 400mL of acetonitrile and add them to a three-necked flask under nitrogen protection and stir. Add 40g of propyltriethoxysilane isocyanate solution dropwise to the three-necked flask. After the addition is complete, raise the temperature of the three-necked flask to 50℃ and keep it at that temperature for 3 hours. Then raise the temperature of the three-necked flask to 65℃ and remove the solvent under reduced pressure to obtain the reinforcing modifier.

[0041] S4. Place the bundled basalt fibers in a calcination furnace at 400℃ and calcine for 3 hours. After the furnace temperature is reduced to room temperature, wash with purified water and transfer to a drying oven at 70℃ to dry to constant weight to obtain calcined fibers. The density of the bundled basalt fibers is 2.6 g / cm³. 3 The length is 17-19mm and the diameter is 0.2-0.8mm.

[0042] S5. Mix 7 mol / L sulfuric acid, 8 wt% hydrogen peroxide and 5 mol / L hydrochloric acid in a volume ratio of 10:2:3 to obtain an activation solution for later use.

[0043] The calcined fiber and the activation solution were added to a beaker at a ratio of 1g:8mL and stirred. The temperature of the activation solution was raised to 65℃ and kept at that temperature for 3 hours. The temperature of the beaker was then lowered to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 70℃ and dried to constant weight to obtain the activated fiber.

[0044] S6. Weigh 300g of activated fiber, 200g of reinforcing modifier, and 2000mL of anhydrous ethanol and add them to a 5L three-necked flask. Stir for 20min and raise the temperature of the three-necked flask to 60℃. Add 800mL of 5wt% sodium hydroxide solution dropwise to the three-necked flask. After the addition is complete, keep the reaction at the temperature for 4h. Lower the temperature of the three-necked flask to room temperature, filter, and wash the filter cake three times with purified water and anhydrous ethanol respectively. Then dry the filter cake and transfer it to a drying oven at 70℃. Dry it to constant weight to obtain bundled reinforcing fibers.

[0045] Example 2

[0046] This embodiment provides a method for preparing bundled reinforcing fibers for freeze-thaw resistant, high-dosage bundled basalt fiber-reinforced concrete, comprising the following steps:

[0047] S1. Mix thionyl chloride and dichloromethane at a weight ratio of 1:4 to obtain a thionyl chloride solution for later use.

[0048] Weigh out 500g of polyethylene glycol monomethyl ether, 500mL of dichloromethane, and 25g of potassium carbonate and add them to a three-necked flask. Stir the mixture and raise the temperature of the three-necked flask to a state of slight reflux. Add 20g of thionyl chloride solution dropwise to the three-necked flask. After the addition is complete, keep the mixture at this temperature for 21 hours. Then, lower the temperature of the three-necked flask to room temperature, filter the mixture, and transfer the filtrate to a rotary evaporator. Set the water bath temperature to 40℃ and remove the solvent under reduced pressure to obtain chlorinated polyethylene glycol monomethyl ether.

[0049] S2. Weigh 53g of chlorinated polyethylene glycol monomethyl ether and 150mL of acetonitrile into a three-necked flask protected by nitrogen and light. Heat and stir until the system dissolves. Add 25g of potassium carbonate and 1g of potassium iodide to the three-necked flask. Raise the temperature of the three-necked flask to allow the system to reflux slightly. Add 3g of ethanolamine dropwise to the three-necked flask. After the addition is complete, keep the reaction at this temperature for 21 hours. Lower the temperature of the three-necked flask to room temperature, filter, and transfer the filtrate to a rotary evaporator. Set the water bath temperature to 55℃ and remove the solvent under reduced pressure. Add 50g of toluene to the rotary evaporator and mix thoroughly. Raise the water bath temperature to 90℃ and distill under reduced pressure until no liquid flows out, obtaining modified polyethylene glycol monomethyl ether.

[0050] S3. Mix propyltriethoxysilane isocyanate and acetonitrile at a weight ratio of 1:3 to obtain a propyltriethoxysilane isocyanate solution for later use.

[0051] Weigh 42g of modified polyethylene glycol monomethyl ether and 400mL of acetonitrile and add them to a three-necked flask under nitrogen protection and stir. Add 40g of propyltriethoxysilane isocyanate solution dropwise to the three-necked flask. After the addition is complete, raise the temperature of the three-necked flask to 55℃ and keep it at that temperature for 4 hours. Then raise the temperature of the three-necked flask to 70℃ and remove the solvent under reduced pressure to obtain the reinforcing modifier.

[0052] S4. Place the bundled basalt fibers in a calcination furnace at 400-500℃ and calcinate for 4 hours. After the furnace temperature is reduced to room temperature, wash with purified water and transfer to a drying oven at 75℃ to dry to constant weight to obtain calcined fibers. The density of the bundled basalt fibers is 2.6 g / cm³. 3 The length is 17-19mm and the diameter is 0.2-0.8mm.

[0053] S5. Mix 7 mol / L sulfuric acid, 8 wt% hydrogen peroxide and 5 mol / L hydrochloric acid in a volume ratio of 10:2:3 to obtain an activation solution for later use.

[0054] The calcined fiber and the activation solution were added to a beaker at a ratio of 1g:8mL and stirred. The temperature of the activation solution was raised to 70℃ and kept at that temperature for 4 hours. The temperature of the beaker was then lowered to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 75℃ and dried to constant weight to obtain the activated fiber.

[0055] S6. Weigh 300g of activated fiber, 200g of reinforcing modifier and 2000mL of anhydrous ethanol and add them to a 5L three-necked flask. Stir for 25min. Raise the temperature of the three-necked flask to 65℃. Add 800mL of 5wt% sodium hydroxide solution dropwise to the three-necked flask. After the addition is complete, keep the reaction at the temperature for 5h. Lower the temperature of the three-necked flask to room temperature, filter, wash the filter cake three times with purified water and anhydrous ethanol respectively, and then dry it. Transfer the filter cake to a drying oven at 75℃ and dry it to constant weight to obtain bundled reinforcing fibers.

[0056] Example 3

[0057] This embodiment provides a method for preparing bundled reinforcing fibers for freeze-thaw resistant, high-dosage bundled basalt fiber-reinforced concrete, comprising the following steps:

[0058] S1. Mix thionyl chloride and dichloromethane at a weight ratio of 1:4 to obtain a thionyl chloride solution for later use.

[0059] Weigh out 500g of polyethylene glycol monomethyl ether, 500mL of dichloromethane, and 25g of potassium carbonate and add them to a three-necked flask. Stir the mixture and raise the temperature of the three-necked flask to a state of slight reflux. Add 20g of thionyl chloride solution dropwise to the three-necked flask. After the addition is complete, keep the mixture at this temperature for 22 hours. Then, lower the temperature of the three-necked flask to room temperature, filter the mixture, and transfer the filtrate to a rotary evaporator. Set the water bath temperature to 40℃ and remove the solvent under reduced pressure to obtain chlorinated polyethylene glycol monomethyl ether.

[0060] S2. Weigh 53g of chlorinated polyethylene glycol monomethyl ether and 150mL of acetonitrile into a three-necked flask protected by nitrogen and light. Heat and stir until the system dissolves. Add 25g of potassium carbonate and 1g of potassium iodide to the three-necked flask. Raise the temperature of the three-necked flask to allow the system to reflux slightly. Add 3g of ethanolamine dropwise to the three-necked flask. After the addition is complete, keep the reaction at this temperature for 22 hours. Lower the temperature of the three-necked flask to room temperature, filter, and transfer the filtrate to a rotary evaporator. Set the water bath temperature to 55℃ and remove the solvent under reduced pressure. Add 50g of toluene to the rotary evaporator and mix thoroughly. Raise the water bath temperature to 90℃ and distill under reduced pressure until no liquid flows out, obtaining modified polyethylene glycol monomethyl ether.

[0061] S3. Mix propyltriethoxysilane isocyanate and acetonitrile at a weight ratio of 1:3 to obtain a propyltriethoxysilane isocyanate solution for later use.

[0062] Weigh 42g of modified polyethylene glycol monomethyl ether and 400mL of acetonitrile and add them to a three-necked flask under nitrogen protection and stir. Add 40g of propyltriethoxysilane isocyanate solution dropwise to the three-necked flask. After the addition is complete, raise the temperature of the three-necked flask to 60℃ and keep it at that temperature for 5 hours. Then raise the temperature of the three-necked flask to 75℃ and remove the solvent under reduced pressure to obtain the reinforcing modifier.

[0063] S4. Place the bundled basalt fibers in a calcination furnace at 500℃ and calcinate for 5 hours. After the furnace temperature is reduced to room temperature, wash with purified water and transfer to a drying oven at 80℃ to dry to constant weight to obtain calcined fibers. The density of the bundled basalt fibers is 2.6 g / cm³. 3 It is 19mm long and 0.2-0.8mm in diameter.

[0064] S5. Mix 7 mol / L sulfuric acid, 8 wt% hydrogen peroxide and 5 mol / L hydrochloric acid in a volume ratio of 10:2:3 to obtain an activation solution for later use.

[0065] The calcined fiber and the activation solution were added to a beaker at a ratio of 1g:8mL and stirred. The temperature of the activation solution was raised to 75℃ and kept at that temperature for 5 hours. The temperature of the beaker was then lowered to room temperature and filtered. The filter cake was washed with purified water until neutral and then transferred to a drying oven at 80℃ and dried to constant weight to obtain the activated fiber.

[0066] S6. Weigh 300g of activated fiber, 200g of reinforcing modifier and 2000mL of anhydrous ethanol and add them to a 5L three-necked flask. Stir for 30min. Raise the temperature of the three-necked flask to 70℃. Add 800mL of 5wt% sodium hydroxide solution dropwise to the three-necked flask. After the addition is complete, keep the reaction at the temperature for 6h. Lower the temperature of the three-necked flask to room temperature. Filter the mixture. Wash the filter cake three times with purified water and anhydrous ethanol respectively and then dry it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight to obtain bundled reinforcing fibers.

[0067] Example 4

[0068] This embodiment provides a method for preparing freeze-thaw resistant, high-dosage bundled basalt fiber reinforced concrete, including the following steps:

[0069] Step 1

[0070] Select stones with a particle size of 5-20mm as small stones and stones with a particle size of 16-31.5mm as medium stones. Mix the small stones and medium stones evenly at a weight ratio of 1:4 to obtain coarse aggregate.

[0071] River sand with a fineness modulus of 2.6 was selected as the fine aggregate;

[0072] A polycarboxylate superplasticizer with a water reduction rate of 19.4% was selected as the admixture;

[0073] Slag, fly ash, and silicate cement were mixed evenly in a weight ratio of 3:1:6 to obtain composite cement. The slag used was Yangtze River S95 mineral powder with a strength activity index of 106%; the fly ash used was Class F Grade I fly ash with a strength activity index of 73%; and the silicate cement grade was P.II 52.5.

[0074] The bundled reinforcing fiber prepared in Example 1 was selected as the bundled reinforcing fiber used in this example.

[0075] Step Two

[0076] Weigh out 7 kg of coarse aggregate, 3 kg of fine aggregate, and 2.5 kg of composite cement and add them to the concrete mixer. Set the speed to 15 r / min and mix for 2 min.

[0077] Add 4.5 kg of drinking water and 60 g of admixture to the concrete mixer and mix for 4 minutes;

[0078] Add 800g of bundled reinforcing fibers to the concrete mixer and continue mixing for 2 minutes;

[0079] Add 210g of admixture and 14kg of drinking water to the concrete mixer and mix for 5 minutes;

[0080] The output material yielded basalt fiber-reinforced antifreeze concrete.

[0081] Example 5

[0082] This embodiment provides a method for preparing freeze-thaw resistant, high-dosage bundled basalt fiber reinforced concrete, including the following steps:

[0083] Step 1

[0084] Select stones with a particle size of 5-20mm as small stones and stones with a particle size of 16-31.5mm as medium stones. Mix the small stones and medium stones evenly at a weight ratio of 1:4 to obtain coarse aggregate.

[0085] River sand with a fineness modulus of 2.6 was selected as the fine aggregate;

[0086] A polycarboxylate superplasticizer with a water reduction rate of 19.4% was selected as the admixture;

[0087] Slag, fly ash, and silicate cement were mixed evenly in a weight ratio of 3:1:6.5 to obtain composite cement. The slag used was Yangtze River S95 mineral powder with a strength activity index of 106%; the fly ash used was Class F Grade I fly ash with a strength activity index of 73%; and the silicate cement grade was P.II 52.5.

[0088] The bundled reinforcing fiber prepared in Example 2 was selected as the bundled reinforcing fiber used in this example.

[0089] Step Two

[0090] Weigh out 7.5 kg of coarse aggregate, 3.3 kg of fine aggregate, and 2.7 kg of composite cement and add them to the concrete mixer. Set the speed to 15 r / min and mix for 2.5 min.

[0091] Add 5 kg of drinking water and 75 g of admixture to the concrete mixer and mix for 5 minutes;

[0092] Add 1000g of bundled reinforcing fibers to the concrete mixer and continue mixing for 2.5 minutes;

[0093] Add 175g of admixture and 12kg of drinking water to the concrete mixer and mix for 7 minutes;

[0094] The output material yielded basalt fiber-reinforced antifreeze concrete.

[0095] Example 6

[0096] This embodiment provides a method for preparing freeze-thaw resistant, high-dosage bundled basalt fiber reinforced concrete, including the following steps:

[0097] Step 1

[0098] Select stones with a particle size of 5-20mm as small stones and stones with a particle size of 16-31.5mm as medium stones. Mix the small stones and medium stones evenly at a weight ratio of 1:4 to obtain coarse aggregate.

[0099] River sand with a fineness modulus of 2.6 was selected as the fine aggregate;

[0100] A polycarboxylate superplasticizer with a water reduction rate of 19.4% was selected as the admixture;

[0101] Slag, fly ash, and silicate cement were mixed evenly in a weight ratio of 3:1:7 to obtain composite cement. The slag used was Yangtze River S95 mineral powder with a strength activity index of 106%; the fly ash used was Class F Grade I fly ash with a strength activity index of 73%; and the silicate cement grade was P.II 52.5.

[0102] The bundled reinforcing fiber prepared in Example 3 was selected as the bundled reinforcing fiber used in this example.

[0103] Step Two

[0104] Weigh out 8 kg of coarse aggregate, 3.5 kg of fine aggregate, and 3 kg of composite cement and add them to the concrete mixer. Set the speed to 15 r / min and mix for 3 minutes.

[0105] Add 6 kg of drinking water and 90 g of admixture to the concrete mixer and mix for 6 minutes;

[0106] Add 1200g of bundled reinforcing fibers to the concrete mixer and continue mixing for 3 minutes;

[0107] Add 140g of admixture and 10.5kg of drinking water to the concrete mixer and mix for 8 minutes;

[0108] The output material yielded basalt fiber-reinforced antifreeze concrete.

[0109] Comparative Example 1

[0110] The difference between this comparative example and Example 4 is that the silicate cement used in step one is used in an equal amount to replace the composite cement in step two.

[0111] Comparative Example 2

[0112] The difference between this comparative example and Example 4 is that no bundled reinforcing fibers were added in step two.

[0113] Comparative Example 3

[0114] The difference between this comparative example and Example 4 is that the bundled reinforcing fibers in step two are replaced by bundled basalt fibers in Example 1 in an equal amount.

[0115] Performance testing:

[0116] According to the specimen preparation and curing standards in GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the basalt fiber reinforced antifreeze concrete prepared in Examples 4-6 and Comparative Examples 1-3 were prepared into concrete specimens with dimensions of 100×100×400mm and 100×100×100mm. The freeze-thaw test was conducted using the rapid thawing method according to GB / T 50081-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete". The compressive strength and splitting tensile strength of a 100×100×400mm specimen were tested before and after 100 freeze-thaw cycles, in accordance with standard CECS13-2009 "Standard for Test Methods of Fiber Reinforced Concrete". The mass loss and relative dynamic modulus of elasticity of a 100×100×100mm specimen were tested before and after 100 freeze-thaw cycles, in accordance with standard GB / T 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". The specific test results are shown in the table below:

[0117]

[0118]

[0119] Data Analysis:

[0120] By comparing and analyzing the data in the table above, the concrete specimens prepared by Examples 4-5 of this invention have a compressive strength of 69.68 MPa and a splitting tensile strength of 4.83 MPa. After 100 freeze-thaw cycles, the compressive strength of the specimens reaches 53.46 MPa with a compressive strength retention rate of 76.7%, the splitting tensile strength reaches 3.95 MPa with a splitting tensile strength retention rate of 81.8%, and the mass loss rate of the specimens after 100 freeze-thaw cycles reaches 1.8%, and the relative dynamic modulus of elasticity reaches 97.0%. All test data are better than those of the comparative examples, indicating that the concrete specimens prepared by this invention, through the optimization of the coarse aggregate particle size ratio and the combination of composite cement and bundled reinforcing fibers, effectively improve the compressive strength, splitting tensile strength and freeze-thaw resistance of the concrete specimens.

[0121] The data for Comparative Example 3 are much lower than those for other examples or comparative examples because, during the experiment, the cement concrete in Comparative Example 3 did not have basalt fiber modified and reinforced. As a result, the concrete became viscous during mixing and it was difficult to form a uniform paste. The basalt fiber and concrete composition were difficult to disperse evenly. After 100 freeze-thaw cycles, the specimens were difficult to form relatively complete testable blocks, and the mass loss rate and relative dynamic modulus of elasticity were difficult to calculate.

[0122] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0123] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0124] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A freeze-thaw resistant, high-content bundled basalt fiber-reinforced concrete, characterized in that, It includes the following components by weight: 70-78 parts coarse aggregate, 30-35 parts fine aggregate, 25-30 parts composite cement, 0.2-0.3 parts admixture, 0.8-1.2 parts bundled reinforcing fibers, and 15-20 parts water; The composite cement is composed of slag, fly ash, and silicate cement in a weight ratio of 3:1:6-7. The strength activity index of the slag is 106%. The fly ash used is Class F Grade I fly ash with a strength activity index of 73%. The grade of the silicate cement is P.II52.

5. The bundled reinforcing fibers are obtained by the following steps: A1. Place the bundled basalt fibers in a calcination furnace at a temperature of 400-500℃ and calcinate for 3-5 hours. After the temperature of the calcination furnace is reduced to room temperature, wash with purified water and transfer to a drying oven at a temperature of 70-80℃ to dry to constant weight to obtain calcined fibers. A2. Add the calcined fiber and activation solution to a beaker and stir. Raise the temperature of the activation solution to 65-75℃ and keep it warm for 3-5 hours. The activated fiber is then obtained through post-treatment. A3. Add the activated fiber, reinforcing modifier and anhydrous ethanol to a three-necked flask, stir for 20-30 min, raise the temperature of the three-necked flask to 60-70℃, add the catalyst dropwise to the three-necked flask, and after the addition is complete, keep the reaction at the temperature for 4-6 h, and then process to obtain bundled reinforcing fibers. The reinforcing modifier is obtained through the following steps: B1. Add polyethylene glycol monomethyl ether, dichloromethane and potassium carbonate to a three-necked flask, heat and stir until the system is dissolved, raise the temperature of the three-necked flask to the point where the system is slightly refluxed, add thionyl chloride solution dropwise to the three-necked flask, and after the addition is complete, keep the reaction at the temperature for 20-22 hours, and then process to obtain chlorinated polyethylene glycol monomethyl ether. B2. Chlorinated polyethylene glycol monomethyl ether and acetonitrile were added to a three-necked flask under nitrogen and light protection. The mixture was heated and stirred until dissolved. Potassium carbonate and potassium iodide were added to the three-necked flask. The temperature of the three-necked flask was raised to a point where the system was under slight reflux. Ethanolamine was added dropwise to the three-necked flask. After the addition was complete, the reaction was maintained at this temperature for 20-22 hours. The modified polyethylene glycol monomethyl ether was obtained after post-treatment. B3. Add modified polyethylene glycol monomethyl ether and acetonitrile to a three-necked flask under nitrogen protection and stir. Add propyltriethoxysilane isocyanate solution dropwise to the three-necked flask. After the addition is complete, raise the temperature of the three-necked flask to 50-60℃ and keep it at that temperature for 3-5 hours. The post-treatment yields the reinforcing modifier.

2. The freeze-thaw resistant high-content bundled basalt fiber reinforced concrete according to claim 1, characterized in that, The coarse aggregate is composed of small stones and medium stones mixed in a weight ratio of 1:4, wherein the small stone particle size is 5-20mm and the medium stone particle size is 16-31.5mm; the fine aggregate is river sand with a fineness modulus of 2.6; the admixture is polycarboxylate superplasticizer with a water reduction rate of 19.4%.

3. The freeze-thaw resistant high-content bundled basalt fiber reinforced concrete according to claim 1, characterized in that, The density of the bundled basalt fibers in step A1 is 2.6 g / cm³. 3 The length is 17-19 mm and the diameter is 0.2-0.8 mm; the activation solution in step A2 is composed of 7 mol / L sulfuric acid, 8 wt% hydrogen peroxide and 5 mol / L hydrochloric acid in a volume ratio of 10:2:

3.

4. The freeze-thaw resistant high-dosage bundled basalt fiber reinforced concrete according to claim 1, characterized in that, In step A3, the ratio of activated fiber, reinforcing modifier, anhydrous ethanol and catalyst is 3g:2g:20mL:8mL, and the catalyst is a 5wt% sodium hydroxide solution.

5. The freeze-thaw resistant high-content bundled basalt fiber reinforced concrete according to claim 1, characterized in that, In step B1, the polyethylene glycol monomethyl ether is polyethylene glycol monomethyl ether 500, and the ratio of polyethylene glycol monomethyl ether, dichloromethane, potassium carbonate and thionyl chloride solution is 50g:500mL:25g:20g. The thionyl chloride solution is composed of thionyl chloride and dichloromethane in a weight ratio of 1:

4.

6. The freeze-thaw resistant high-dosage bundled basalt fiber reinforced concrete according to claim 1, characterized in that, In step B2, the ratio of chlorinated polyethylene glycol monomethyl ether, acetonitrile, potassium carbonate, potassium iodide and ethanolamine is 53g:150mL:25g:1g:3g.

7. The freeze-thaw resistant high-dosage bundled basalt fiber reinforced concrete according to claim 1, characterized in that, In step B3, the ratio of modified polyethylene glycol monomethyl ether, acetonitrile, and propyltriethoxysilane isocyanate solution is 21g:200mL:20g, wherein the propyltriethoxysilane isocyanate solution is composed of propyltriethoxysilane and acetonitrile in a weight ratio of 1:3.

Images