High-toughness polypropylene fiber concrete and preparation method thereof
By preparing curing agent-modified polypropylene fibers and combining them with water-based epoxy resin, the problems of weak bonding ability and high combustion risk of polypropylene fibers were solved, and the high toughness and flame retardant properties were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-10
- Publication Date
- 2026-04-10
AI Technical Summary
Polypropylene fibers have weak bonding ability with cement paste, which easily forms weak areas, resulting in poor modification effect. At the same time, the flammability of epoxy resin increases the risk of combustion.
A curing agent was prepared by reacting phenylphosphoryl dichloride with aminosilane, which was then used to modify polypropylene fibers and bonded to waterborne epoxy resin to form a stable silicon-carbon barrier layer, thereby improving interfacial bonding ability and flame retardant properties.
It improves the interfacial bonding between polypropylene fibers and the concrete matrix, reduces the risk of combustion, and enhances the toughness and impact resistance of concrete.
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of building materials, and particularly relates to a high-toughness polypropylene fiber concrete and a preparation method thereof. BACKGROUND
[0002] Polypropylene fibers can form a three-dimensional network structure in a random distribution in the interior of concrete, effectively block the development of cracks, and bear tension when the concrete is subjected to external force, delay crack propagation, and significantly improve the fracture energy and toughness of the concrete. However, the surface of the polypropylene fiber is hydrophobic, and the bonding capacity with the cement paste is weak, which easily forms a weak zone at the interface. This makes the modification effect of the polypropylene fiber on the concrete often fail to meet the expected requirements. Further adding epoxy resin can solve the stress concentration problem of the polypropylene fiber in the concrete, but the epoxy resin is a flammable material, and adding the epoxy resin in the concrete may increase the risk of combustion of the concrete and reduce the safety performance of the concrete. To solve the above technical defects, the application provides a high-toughness polypropylene fiber concrete and a preparation method thereof. SUMMARY
[0003] The application aims to provide a high-toughness polypropylene fiber concrete and a preparation method thereof, and solve the problems mentioned in the background.
[0004] The purpose of the application can be achieved by the following technical solutions. A preparation method of a high-toughness polypropylene fiber concrete, comprising the following steps: Firstly, a curing agent is obtained by a nucleophilic substitution reaction between phenylphosphoryl dichloride and aminosilane.
[0005] Secondly, modified polypropylene fibers are obtained by grafting a silane coupling agent on the surface of the polypropylene fibers.
[0006] Thirdly, a concrete dry material is obtained by uniformly mixing Portland cement, coarse aggregate, fine aggregate, mineral admixture and the modified polypropylene fibers. Then, water, polycarboxylate superplasticizer and air entraining agent are added to the concrete dry material, and the mixture is uniformly stirred to obtain a concrete mixture.
[0007] Fourthly, water-based epoxy resin and the curing agent are added to the concrete mixture, and the mixture is uniformly stirred to obtain a concrete slurry. The concrete slurry is then poured, vibrated and compacted, and covered with a plastic film. After 48-72 hours, the formwork is removed and the high-toughness polypropylene fiber concrete is obtained after curing.
[0008] There is no sequence between the first step and the second step in the preparation method.
[0009] As a further preferred embodiment of the present application, the aminosilane is at least one of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 1,3-bis(2-amine ethyl amine methyl) tetramethyldisiloxane.
[0010] As a further preferred embodiment of the present application, the length specification of the polypropylene fiber is 6-12 mm.
[0011] As a further preferred embodiment of the present application, the silane coupling agent is silane coupling agent kh-550.
[0012] As a further preferred embodiment of the present application, the coarse aggregate is graded gravel, and the particle size specification of the graded gravel is 5-25 mm.
[0013] As a further preferred embodiment of the present application, the fine aggregate is river sand, and the silt content of the river sand is ≤3%, and the fineness modulus is 2.4-3.2.
[0014] As a further preferred embodiment of the present application, the mineral admixture is at least one of I-grade fly ash and II-grade fly ash.
[0015] As a further preferred embodiment of the present application, the air entraining agent is 126A.
[0016] As a further preferred embodiment of the present application, the mass fraction ratio of Portland cement, coarse aggregate, fine aggregate, mineral admixture, modified polypropylene fiber, water, polycarboxylic acid water reducer, air entraining agent, water-based epoxy resin, curing agent is 200-220:660-720:480-520:54-60:2-2.2:100-110:4-4.4:0.12-0.14:12.5-13.7:7.5-8.3.
[0017] A high-toughness polypropylene fiber concrete is prepared by any of the above preparation steps.
[0018] The present application has at least the following beneficial effects: The present application effectively improves the interfacial bonding capacity of polypropylene fiber and concrete matrix by compounding epoxy resin and polypropylene fiber, solves the stress concentration problem that may be caused by adding polypropylene fiber alone in concrete, and uses a self-made curing agent with phosphate structure to improve the flame retardant performance of the epoxy resin, and solves the problem of increased risk of combustion caused by adding epoxy resin in concrete.
[0019] The curing agent is synthesized by the reaction of phenylphosphonic dichloride and aminosilane, and can fully exert the phosphorus-silicon synergistic flame-retardant effect, wherein the phosphorus element decomposes in the gas phase to generate a free radical trapping agent to inhibit the combustion chain reaction, and the silicon element promotes the formation of a stable and dense silicon-carbon barrier layer in the condensed phase to effectively isolate heat and oxygen transmission, thereby greatly improving the flame-retardant performance of the epoxy resin; compared with the modification method of physically blending the flame retardant, the curing agent of the application can enter the crosslinked network of the epoxy resin through chemical bonding to realize targeted flame retardation, and significantly reduce the total addition amount of the flame retardant.
[0020] The curing agent of the application has both primary amine and secondary amine structures, and the tertiary amine structure generated after the curing of the secondary amine structure can catalyze the ring-opening reaction of the epoxy group, thereby improving the curing speed of the epoxy resin concrete in a medium-low temperature environment; in addition, the Si-O-Si structure in the curing agent can effectively dissipate external impact energy by utilizing its high rotational freedom, thereby improving the toughness and impact strength of the epoxy resin concrete. DETAILED DESCRIPTION
[0021] The technical solutions of the embodiments of the application will be described below clearly and completely. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the specification of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the application.
[0022] In the application, all raw materials have no particular restrictions on their sources, and can be purchased on the market or prepared according to conventional methods well known to those skilled in the art. Embodiment 1
[0023] A preparation method of a high-toughness polypropylene fiber concrete comprises the following steps: In the first step, 13.9 parts of 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane and 5 parts of triethylamine are added into a three-necked flask provided with a condenser, a thermometer and a magnetic stirring rotor, the temperature of the system is raised to 50 DEG C after the magnetic stirring is started, then 4.8 parts of phenylphosphonic dichloride is added dropwise into the system, the dropping time is 60 min, after the dropping is completed, the reaction is continued at 50 DEG C for 40 min, then deionized water is added into the three-necked flask for cooling, and dichloromethane is used for extraction, the organic phase is separated by a separatory funnel, then the organic phase is dried and rotated to remove the solvent, and the curing agent is obtained.
[0024] Second step, according to mass fraction, 2 parts of polypropylene fiber with length of 6mm are treated by corona, then are added into a three-necked flask provided with a condenser, a thermometer and a magnetic stirring rotor, 40 parts of 60% by volume of ethanol aqueous solution and 0.5 parts of silane coupling agent KH-550 are added into the three-necked flask, then the magnetic stirring is started, and the reaction is carried out at a temperature of 40℃ for 10 hours, after the reaction is completed, the polypropylene fiber is filtered, washed with anhydrous ethanol and deionized water in sequence, and dried to obtain modified polypropylene fiber.
[0025] Third step, according to mass fraction, 200 parts of Portland cement, 600 parts of graded gravel with particle size specification of 5-25mm, 480 parts of river sand with 3% of silt content and fineness modulus of 3.2, 54 parts of I-grade fly ash, and 2 parts of modified polypropylene fiber are uniformly mixed to obtain dry concrete material, then 100 parts of water, 4 parts of polycarboxylic acid water reducing agent, and 0.12 parts of air entraining agent 126A are added into the dry concrete material, and after being uniformly mixed and stirred, the concrete mixture is obtained.
[0026] Fourth step, according to mass fraction, 12.5 parts of water-based epoxy resin and 7.5 parts of curing agent are added into the concrete mixture, and after being uniformly mixed and stirred, the concrete slurry is obtained, then the concrete slurry is poured and vibrated and compacted, and is covered with plastic film, after 48 hours after the pouring is completed, the formwork is removed and cured to obtain high-toughness polypropylene fiber concrete.
[0027] A high-toughness polypropylene fiber concrete is prepared by the above preparation steps. Example 2
[0028] A preparation method of high-toughness polypropylene fiber concrete comprises the following steps: First step, according to mass fraction, 3.7 parts of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 9.7 parts of 1,3-bis(2-amine ethyl amine methyl) tetramethyldisiloxane, and 6 parts of triethylamine are added into a three-necked flask provided with a condenser, a thermometer and a magnetic stirring rotor, the temperature of the system is raised to 55℃ after the magnetic stirring is started, then 4.8 parts of phenyl phosphorodichloridate is added dropwise into the system, the dropwise adding time is 60 minutes, after the dropwise adding is completed, the reaction is continuously carried out at a temperature of 55℃ for 35 minutes, after the reaction is completed, deionized water is added into the three-necked flask for cooling, and dichloromethane is used for extraction, the organic phase is separated by a separatory funnel, and the organic phase is dried and rotated to remove the solvent to obtain a curing agent.
[0029] Step 2: According to the mass fraction, 2.1 parts of polypropylene fiber with a length of 9 mm were corona treated and added to a three-necked flask equipped with a condenser, thermometer, and magnetic stirrer. 45 parts of 50% ethanol aqueous solution and 0.55 parts of silane coupling agent KH-550 were added to the three-necked flask. Then, the magnetic stirrer was turned on and the reaction was carried out at 50°C for 8 hours. After the reaction was completed, the polypropylene fiber was filtered out, washed with anhydrous ethanol and deionized water in sequence, and then dried to obtain modified polypropylene fiber.
[0030] The third step involves mixing 210 parts by weight of silicate cement, 660 parts by weight of graded crushed stone with a particle size of 5-25mm, 500 parts by weight of river sand with a mud content of 2% and a fineness modulus of 2.8, 57 parts by weight of grade II fly ash, and 2.1 parts by weight of modified polypropylene fiber to obtain dry concrete mix. Then, 105 parts by weight of water, 4.2 parts by weight of polycarboxylate superplasticizer, and 0.13 parts by weight of air-entraining agent 126A are added to the dry concrete mix and stirred until homogeneous to obtain concrete paste.
[0031] Step 4: Add 13.1 parts water-based epoxy resin and 7.9 parts curing agent to the concrete mix according to the mass ratio. After mixing evenly, the concrete slurry is obtained. After pouring the concrete slurry, vibrate it to make it dense and cover it with plastic film. After 60 hours of pouring, remove the formwork and cure to obtain high-toughness polypropylene fiber concrete.
[0032] A high-toughness polypropylene fiber concrete is prepared by the above preparation steps. Example 3
[0033] A method for preparing high-toughness polypropylene fiber reinforced concrete includes the following steps: Step 1: According to the mass fractions, 7.4 parts of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, 5.5 parts of 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane, and 7 parts of triethylamine were added to a three-necked flask equipped with a condenser, thermometer, and magnetic stirrer. After turning on the magnetic stirrer, the system temperature was raised to 60°C. Then, 4.8 parts of phenylphosphodichlorophenoxide were added dropwise to the system over a period of 60 minutes. After the addition was complete, the reaction was continued at 60°C for another 30 minutes. After the reaction was completed, deionized water was added to the three-necked flask for cooling, and the mixture was extracted with dichloromethane. The organic phase was separated using a separatory funnel, dried, and the solvent was removed by rotation to obtain the curing agent.
[0034] Second step, 2.2 parts of polypropylene fiber with a length of 12 mm are added to a three-necked flask equipped with a condenser, a thermometer and a magnetic stirring rotor after being treated by corona discharge, and 50 parts of 40% ethanol aqueous solution by volume fraction and 0.6 parts of silane coupling agent KH-550 are added to the three-necked flask, then the magnetic stirring is started, and the reaction is carried out at a temperature of 60℃ for 6 hours, after the reaction is completed, the polypropylene fiber is filtered out, and then is washed with anhydrous ethanol and deionized water in sequence and dried to obtain modified polypropylene fiber.
[0035] Third step, 220 parts of Portland cement, 720 parts of graded gravel with a particle size specification of 5-25 mm, 520 parts of river sand with a clay content of 1% and a fineness modulus of 2.4, 60 parts of Class I fly ash, and 2.2 parts of modified polypropylene fiber are uniformly mixed to obtain concrete dry material, then 110 parts of water, 4.4 parts of polycarboxylic acid water reducer, and 0.14 parts of air entraining agent 126A are added to the concrete dry material, and the mixture is uniformly stirred to obtain concrete mixture.
[0036] Fourth step, 13.7 parts of water-based epoxy resin and 8.3 parts of curing agent are added to the concrete mixture, and the mixture is uniformly stirred to obtain concrete slurry, then the concrete slurry is poured and vibrated and compacted, and is covered with a plastic film, after 72 hours of pouring, the formwork is removed and cured to obtain high-toughness polypropylene fiber concrete.
[0037] A high-toughness polypropylene fiber concrete is prepared by the above preparation steps.
[0038] Comparative Example 1 The difference between this example and Comparative Example 1 is that the curing agent is not prepared separately, but amino silane is used to cure the epoxy resin, and a conventional flame retardant is additionally added to the concrete.
[0039] A method for preparing a high-toughness polypropylene fiber concrete, comprising the following steps: First step, 2 parts of polypropylene fiber with a length of 6 mm are added to a three-necked flask equipped with a condenser, a thermometer and a magnetic stirring rotor after being treated by corona discharge, and 40 parts of 60% ethanol aqueous solution by volume fraction and 0.5 parts of silane coupling agent KH-550 are added to the three-necked flask, then the magnetic stirring is started, and the reaction is carried out at a temperature of 40℃ for 10 hours, after the reaction is completed, the polypropylene fiber is filtered out, and then is washed with anhydrous ethanol and deionized water in sequence and dried to obtain modified polypropylene fiber.
[0040] Second step, 200 parts of Portland cement, 600 parts of graded gravel with particle size specification of 5-25 mm, 480 parts of river sand with 3% of silt content and 3.2 of fineness modulus, 54 parts of I-grade fly ash, 2 parts of modified polypropylene fiber are mixed uniformly to obtain concrete dry material, then 100 parts of water, 4 parts of polycarboxylic acid water reducer, 0.12 parts of air entraining agent 126A are added into the concrete dry material, and after stirring and mixing uniformly, concrete mixture is obtained.
[0041] Third step, 12.5 parts of water-based epoxy resin, 7.5 parts of 1,3-bis(2-aminoethyl aminomethyl) tetramethyl disiloxane, 4.8 parts of flame retardant DOPO are added into the concrete mixture, and after stirring and mixing uniformly, concrete slurry is obtained, then the concrete slurry is poured, vibrated and compacted, and covered with plastic film, after 48 h of pouring, the formwork is removed and cured to obtain high-toughness polypropylene fiber concrete.
[0042] A kind of high-toughness polypropylene fiber concrete is prepared by the above preparation steps.
[0043] Comparative Example 2 The difference between this comparative example and Example 1 is that the curing agent is not prepared separately, but a commercially available curing agent is used to cure the epoxy resin, and a commercially available flame retardant is blended to improve the flame retardant effect.
[0044] The difference between this example and Comparative Example 1 is that the curing agent is not prepared separately, but amino silane is added as a curing agent, and a conventional flame retardant is additionally added to the concrete.
[0045] A method for preparing a high-toughness polypropylene fiber concrete, comprising the following steps: First step, 2 parts of polypropylene fiber with a length of 6 mm are subjected to corona treatment, then added into a three-necked flask equipped with a condenser, a thermometer and a magnetic stirring rotor, 40 parts of 60% by volume ethanol aqueous solution and 0.5 parts of silane coupling agent kh-550 are added into the three-necked flask, then the magnetic stirring is started, and the reaction is carried out at a temperature of 40℃ for 10 h, after the reaction is completed, the polypropylene fiber is filtered out, washed with anhydrous ethanol and deionized water in sequence, and dried to obtain modified polypropylene fiber.
[0046] Second step, 200 parts of Portland cement, 600 parts of graded gravel with particle size specification of 5-25 mm, 480 parts of river sand with 3% of silt content and 3.2 of fineness modulus, 54 parts of I-grade fly ash, 2 parts of modified polypropylene fiber are mixed uniformly to obtain concrete dry material, then 100 parts of water, 4 parts of polycarboxylic acid water reducer, 0.12 parts of air entraining agent 126A are added into the concrete dry material, and after stirring and mixing uniformly, concrete mixture is obtained.
[0047] Third step, 12.5 parts of water-based epoxy resin, 7.5 parts of hexanediamine, 4.8 parts of flame retardant DOPO are added into the concrete mixture by mass fraction, and the concrete slurry is obtained after stirring and mixing uniformly, then the concrete slurry is poured, vibrated and compacted and covered with plastic film, after 48h after pouring, the formwork is removed and cured to obtain high-toughness polypropylene fiber concrete.
[0048] A high-toughness polypropylene fiber concrete is prepared by the above preparation steps.
[0049] Experimental example 1 The concrete test pieces in examples 1-3 and comparative examples 1-2 are respectively tested for performance, and the compressive strength after curing for 3 days and 28 days, the impact strength after curing for 28 days, and the flame retardant performance of each component concrete test piece are tested.
[0050] Compressive strength test: tested according to the national standard GB / T 50081-2019 "Standard for testing methods of mechanical properties of ordinary concrete".
[0051] Impact strength: tested according to the national standard GB / T 21120-2018 "Test method for impact resistance of concrete".
[0052] Flame retardant performance test: tested according to the national standard GB 8624-2012 "Building material combustion performance classification method".
[0053] The high-toughness polypropylene fiber concrete prepared by using the curing agent of the present application has higher compressive strength at the initial curing stage, and has good impact toughness and fire resistance after complete curing. The high-toughness polypropylene fiber concrete in comparative example 1 has more flame retardant added, but the flame retardant component is dispersed between the epoxy resin and the non-flammable concrete material, which prevents the flame retardant from effectively protecting the epoxy resin. In addition, the added flame retardant hinders the contact between the epoxy resin molecules and the curing agent, delaying the curing speed of the epoxy resin, thereby causing the initial strength of the concrete to decrease.
[0054] The above examples are only used to help understand the method of the present application and its core idea. Various modifications of these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these examples shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for producing a high-ductility polypropylene fiber concrete, characterized by, The method comprises the following steps: The first step is to carry out a nucleophilic substitution reaction between phenylphosphonic dichloride and an amino silane to obtain a curing agent; The second step is to graft a silane coupling agent on the surface of polypropylene fibers to obtain modified polypropylene fibers; The third step is to mix silicate cement, coarse aggregate, fine aggregate, mineral admixtures, and modified polypropylene fibers uniformly to obtain dry concrete, and then add water, polycarboxylic acid water reducer, and air entraining agent to the dry concrete, mix and stir uniformly to obtain concrete mixture; The fourth step is to add water-based epoxy resin and curing agent to the concrete mixture, mix and stir uniformly to obtain concrete slurry, pour the concrete slurry, compact it by vibrating, cover it with plastic film, and remove the formwork after 48-72 hours of pouring to obtain high-toughness polypropylene fiber concrete after curing and maintenance; There is no sequence between the first and second steps.
2. The method of claim 1, wherein the high ductility polypropylene fiber concrete is prepared by mixing the polypropylene fiber with the cement, the sand, the water, and the additive. The amino silane is at least one of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1,3-bis(2-aminomethyl) tetramethyldisiloxane.
3. The method of claim 1, wherein the high ductility polypropylene fiber concrete is prepared by mixing the polypropylene fiber with the cement, the sand, the water, and the aggregate. The length of the polypropylene fibers is 6-12 mm.
4. The method of claim 1, wherein the high ductility polypropylene fiber concrete is prepared by mixing 0.1 to 0.3 parts by weight of the polypropylene fiber with 100 parts by weight of the cement mortar. The silane coupling agent is silane coupling agent KH-550.
5. The method of claim 1, wherein the high ductility polypropylene fiber concrete is prepared by mixing the polypropylene fiber with the cement, the sand, the water, and the aggregate. The coarse aggregate is graded gravel, and the particle size of the graded gravel is 5-25 mm.
6. The method of claim 1, wherein the high ductility polypropylene fiber concrete is prepared by mixing the polypropylene fiber with the cement, the sand, the water, and the aggregate. The fine aggregate is river sand, and the clay content of the river sand is ≤3%, and the fineness modulus is 2.4-3.
2.
7. The method of claim 1, wherein the high ductility polypropylene fiber concrete is prepared by mixing the polypropylene fiber with the cement, the sand, the water, and the aggregate. The mineral admixtures are at least one of I-grade fly ash and II-grade fly ash.
8. The method of claim 1, wherein the high ductility polypropylene fiber concrete is prepared by mixing the polypropylene fiber with the cement, the sand, the water, and the aggregate. The air entraining agent is 126A.
9. The method of claim 1, wherein the high ductility polypropylene fiber concrete is prepared by mixing the polypropylene fiber with the cement, the sand, the water, and the aggregate. The mass ratio of silicate cement, coarse aggregate, fine aggregate, mineral admixtures, modified polypropylene fibers, water, polycarboxylic acid water reducer, air entraining agent, water-based epoxy resin, and curing agent is 200-220:660-720:480-520:54-60:2-2.2:100-110:4-4.4:0.12-0.14:12.5-13.7:7.5-8.
3.
10. A high ductility polypropylene fiber concrete, characterized by, The high-toughness polypropylene fiber concrete is prepared by the method of any one of claims 1-9. The high-toughness polypropylene fiber concrete is prepared by the method of any one of claims 1-9.