A high-strength concrete for airport pavement and its preparation process

Abstract

The application relates to the technical field of concrete, and particularly discloses high-strength concrete for airport pavements and a preparation process thereof. Raw materials of the high-strength concrete for airport pavements comprise the following components in parts by weight: cement 320-340 parts; fly ash 20-40 parts; sand 590-610 parts; gravel 1380-1400 parts; water reducing agent 6-7 parts; water 125-140 parts; and high-thermal-conductivity energy storage phase change microcapsules 2-4 parts. The high-strength concrete for airport pavements can be used in environments with large temperature differences, and has the advantages of good thermal conductivity and reduced temperature cracks.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to a high-strength concrete for airport pavement and its preparation process. Background Technology

[0002] Nowadays, with the rapid development of my country's economy and the improvement of people's living standards, airplanes have gradually become a common means of transportation for long-distance travel. Among these, the quality of airport concrete pavement is a crucial infrastructure for ensuring aircraft takeoff and landing, and a vital foundation for aircraft safety. Civil aviation airports typically use high-strength concrete for their pavements. As a new building material, high-strength concrete is widely used in civil aviation airport pavements due to its advantages such as high compressive strength, strong resistance to deformation, high density, and low porosity. However, when high-strength concrete is applied to environments with large temperature differences, it is prone to temperature cracking.

[0003] A high-strength concrete is disclosed in the related technology, comprising the following raw materials: 150 parts cement, 140 parts fly ash, 300 parts coarse aggregate, 400 parts river sand, 5 parts water-reducing agent, 120 parts water, and 0.5 parts paraffin phase change microcapsules. The paraffin phase change microcapsules can reduce the generation of temperature cracks.

[0004] Regarding the aforementioned technologies, although paraffin phase change microcapsules are added to concrete, the concrete has many micropores and poor thermal conductivity, resulting in a slow heat transfer rate between the inside and outside of the concrete. Therefore, the paraffin phase change microcapsules are not very effective in reducing temperature cracks. Summary of the Invention

[0005] To reduce cracks in concrete caused by excessive temperature differences, this application provides a high-strength concrete for airport pavements and its preparation process.

[0006] In a first aspect, this application provides a high-strength concrete for airport pavement, employing the following technical solution:

[0007] A high-strength concrete for airport pavement comprises the following components in parts by weight:

[0008] 320-340 parts cement;

[0009] 20-40 parts fly ash;

[0010] 590-610 parts of sand;

[0011] 1380-1400 parts of crushed stone;

[0012] 6-7 parts water-reducing agent;

[0013] 125-140 parts water;

[0014] 2-4 portions of high thermal conductivity energy storage phase change microcapsules;

[0015] The preparation process of the high thermal conductivity energy storage phase change microcapsules includes the following steps:

[0016] Emulsification and dispersion: Paraffin wax, water and emulsifier are mixed and heated to emulsify and disperse, resulting in a paraffin wax emulsion;

[0017] Loading with paraffin: Porous alumina is added to a paraffin emulsion, ultrasonically vibrated, and the solid and liquid are separated to obtain modified alumina particles; Encapsulation treatment: The modified alumina particles are mixed with water evenly, and an aqueous solution of azobisisobutyramidine hydrochloride is added under inert gas protection and heated to obtain a core material solution. The core material solution, water, anhydrous ethanol and pH adjuster are mixed to control the pH to acidic, heated, and a mixture of tetraethyl orthosilicate and anhydrous ethanol is added. The mixture is mixed and reacted, the solid and liquid are separated, and dried to obtain pre-made microcapsules;

[0018] Thermal conductivity modification: High thermal conductivity adhesive is uniformly sprayed onto the surface of the pre-made microcapsules and heated to a semi-cured state to obtain semi-cured microcapsules. Modified thermally conductive carbon fibers are sprayed onto the surface of the semi-cured microcapsules and heated to cure to obtain high thermal conductivity energy storage phase change microcapsules.

[0019] By employing the above technical solution, paraffin wax is loaded into the micropores of porous alumina. On the one hand, the high mechanical strength of porous alumina enhances the pressure resistance of the microcapsules as a supporting structure. On the other hand, the good thermal conductivity of porous alumina improves the thermal conductivity between the microcapsule shell and the paraffin wax. After hydrolysis, tetraethyl orthosilicate coats the surface of the paraffin-loaded porous alumina, forming a silica shell and reducing the probability of paraffin wax leakage. Since concrete has numerous micropores and poor thermal conductivity, the heat transfer rate between the inside and outside of concrete is slow. Therefore, this application uniformly sprays a high thermal conductivity adhesive onto the surface of the precast microcapsules. Semi-curing reduces the probability of adhesive flow and promotes curing. Simultaneously, it prevents the modified thermally conductive carbon fiber from being submerged in or adhering to the adhesive surface. One end of the sprayed modified thermally conductive carbon fiber can be inserted into the high thermal conductivity adhesive layer, while the other end is exposed on the outside of the high thermal conductivity adhesive layer, allowing for subsequent curing and bonding with the cement paste.

[0020] The high thermal conductivity phase change microcapsules obtained in this application exhibit high thermal conductivity and good temperature cycling resistance, essentially not reducing the compressive strength of concrete and reducing the heating and cooling rates of concrete. On one hand, the modified thermally conductive carbon fiber can form a three-dimensional thermally conductive network inside the concrete, which is beneficial for the heat transfer of the high thermal conductivity phase change microcapsules and reduces cracks caused by excessive temperature differences in the concrete. On the other hand, the modified thermally conductive carbon fiber acts as a reinforcement inside the concrete, improving the mechanical properties of the concrete and reducing cracking.

[0021] Optionally, the raw materials of the high thermal conductivity adhesive include the following components in parts by weight:

[0022] 5-10 parts of bisphenol A type epoxy resin;

[0023] 5-8 parts of phenolic epoxy resin;

[0024] 20-35 parts of alumina;

[0025] 30-40 parts of boron nitride;

[0026] 0.2-0.4 parts of silane coupling agent;

[0027] Dispersant 0.1-0.5 parts;

[0028] 2-6 parts of curing agent;

[0029] Solvent 100-150 parts.

[0030] By adopting the above technical solution and adding alumina and boron nitride, which have good thermal conductivity, the thermal conductivity of the adhesive is improved. This not only fixes the modified thermally conductive carbon fiber on the surface of the pre-made microcapsules, but also promotes heat transfer.

[0031] Optionally, in the thermal conductivity modification step, the temperature for heating to semi-curing is 82-88℃, and the time is 6-8 minutes.

[0032] By adopting the above technical solution, this application first heats the high thermal conductivity adhesive to a semi-cured state, so that it can neither flow freely nor allow the modified thermally conductive carbon fiber to be inserted.

[0033] Optionally, the mass ratio of the pre-formed microcapsules to the high thermal conductivity adhesive is 10:(1-2).

[0034] If the amount of high thermal conductivity adhesive used is too small and the thickness of the high thermal conductivity adhesive is too thin, the modified thermally conductive carbon fiber will be difficult to insert and fix on the high thermal conductivity adhesive layer; if the amount of high thermal conductivity adhesive used is too large and the thickness of the high thermal conductivity adhesive layer is too thick, the modified thermally conductive carbon fiber will be easily immersed in the high thermal conductivity adhesive.

[0035] Optionally, the preparation process of the modified thermally conductive carbon fiber includes the following steps:

[0036] Activation treatment involves adding carbon fibers to an ammonium persulfate aqueous solution, stirring and reacting, separating the solid and liquid phases, washing with water, and drying to obtain activated carbon fibers.

[0037] Modification treatment involves adding activated carbon fibers to silica sol, mixing them evenly, separating the solid and liquid phases, and drying to obtain modified thermally conductive carbon fibers.

[0038] By adopting the above technical solution, ordinary carbon fibers have a high thermal conductivity along their axis, but a low thermal conductivity along their radial direction, which is not conducive to heat transfer between carbon fibers in contact. Therefore, this application uses ammonium persulfate aqueous solution to activate carbon fibers, and the modification treatment step causes silica sol to solidify on the surface of carbon fibers to form a silica layer. The thermal conductivity of silica is much higher than that of carbon fibers, which can improve the thermal conductivity of carbon fibers. When the modified thermally conductive carbon fibers come into contact with each other, they can form an efficient heat conduction path.

[0039] Optionally, the length of the modified thermally conductive carbon fiber is 3-5 mm.

[0040] By adopting the above technical solution, if the length of the modified thermally conductive carbon fiber is too short, it will be easily submerged in the high thermal conductivity adhesive; if the length of the modified thermally conductive carbon fiber is too long, it will be difficult to insert into the high thermal conductivity adhesive. Therefore, the preferred length of the modified thermally conductive carbon fiber is 3-5 mm.

[0041] Optionally, the mass concentration of the ammonium persulfate aqueous solution is 8-12 g / L.

[0042] By adopting the above technical solution, if the mass concentration of ammonium persulfate aqueous solution is too low, the oxidation rate will be too slow; if the mass concentration of ammonium persulfate aqueous solution is too high, the oxidation rate will be too fast, which may lead to over-etching and reduce the mechanical properties of carbon fiber. Therefore, the mass concentration of ammonium persulfate aqueous solution is preferably 8-12 g / L.

[0043] Secondly, this application provides a preparation process for high-strength concrete for airport pavements, employing the following technical solution:

[0044] A process for preparing high-strength concrete for airport pavement includes the following steps:

[0045] Step 1: Mix the crushed stone and sand evenly to obtain an aggregate mixture;

[0046] Step 2: Mix cement, fly ash and high thermal conductivity energy storage phase change microcapsules evenly to obtain a mixture;

[0047] Step 3: Mix water and water-reducing agent evenly to obtain a water-reducing agent solution;

[0048] Step four: Mix the admixture solution, aggregate mixture and aggregate evenly to obtain high-strength concrete for airport pavement.

[0049] By adopting the above technical solution, the high thermal conductivity energy storage phase change microcapsules are uniformly dispersed in the material. When the modified thermally conductive carbon fibers come into contact with each other, they can form an efficient thermal conduction path, which is conducive to the heat transfer of the high thermal conductivity energy storage phase change microcapsules and reduces cracks in concrete caused by excessive temperature difference. On the other hand, the modified thermally conductive carbon fibers play a reinforcing role inside the concrete, improving the mechanical properties of the concrete and reducing cracking.

[0050] In summary, this application has the following beneficial effects:

[0051] 1. Because this application adds high thermal conductivity and energy storage phase change microcapsules to concrete, the modified thermally conductive carbon fibers can form an efficient thermal conduction path when they come into contact with each other, which is conducive to the heat transfer of the high thermal conductivity and energy storage phase change microcapsules and reduces cracks in concrete caused by excessive temperature difference.

[0052] 2. Modified thermally conductive carbon fiber can form a three-dimensional network inside concrete, which can play a reinforcing role inside the concrete, improve the mechanical properties of concrete, and reduce cracking.

[0053] 3. This application modifies carbon fibers to solidify silica sol on the surface of carbon fibers, forming a silica layer. Silica has a thermal conductivity much higher than that of carbon fibers, which can improve the thermal conductivity of carbon fibers. When the modified thermally conductive carbon fibers come into contact with each other, they can form an efficient thermal conduction path. Detailed Implementation

[0054] The present application will be further described in detail below with reference to the embodiments.

[0055] Preparation example of high thermal conductivity energy storage phase change microcapsules

[0056] Preparation Example 1

[0057] The preparation process of high thermal conductivity energy storage phase change microcapsules includes the following steps:

[0058] Emulsification and dispersion: Mix 300g of No. 64 paraffin wax, 850g of deionized water and 90g of emulsifier, heat until the paraffin wax is completely melted, the emulsifier is Tween-80, stir and disperse evenly to obtain paraffin wax emulsion;

[0059] Paraffin loading: 950g of porous alumina was added to the paraffin emulsion. The porous alumina had a particle size of 40nm and a pore size range of 10-20nm. The mixture was ultrasonically vibrated for 6min and then filtered to obtain modified alumina particles.

[0060] Encapsulation process: Modified alumina particles and water were mixed evenly at a mass ratio of 1:20. Under nitrogen protection, 1510g of azobisisobutyramidine hydrochloride aqueous solution was added. The azobisisobutyramidine hydrochloride aqueous solution was composed of 10g of azobisisobutyramidine hydrochloride and 1500g of water. After heating to 60℃ and reacting for 8 hours, the core material solution was obtained. The core material solution, water, and anhydrous ethanol were mixed at a mass ratio of 1:2:8. The pH was adjusted to 3, and the mixture was heated to 59℃. A mixture of tetraethyl orthosilicate and anhydrous ethanol was added. The mass ratio of the core material dispersion, tetraethyl orthosilicate, and anhydrous ethanol was 1:0.45:2. The mixture was reacted for 7 hours, filtered, and dried to obtain pre-made microcapsules.

[0061] Thermal conductivity modification: High thermal conductivity adhesive is uniformly sprayed onto the surface of the pre-made microcapsules. The mass ratio of the pre-made microcapsules to the high thermal conductivity adhesive is 10:1. The microcapsules are heated to a semi-cured state at 82°C for 8 minutes to obtain semi-cured microcapsules. 500g of modified thermally conductive carbon fiber with an average length of 3mm is sprayed onto the surface of the semi-cured microcapsules. The microcapsules are then heated to 90°C and cured for 10 minutes to obtain high thermal conductivity energy storage phase change microcapsules.

[0062] The raw materials for the high thermal conductivity adhesive include the following components in parts by weight:

[0063] 5 kg of bisphenol A type epoxy resin, model E44;

[0064] 8 kg of phenolic epoxy resin, epoxy equivalent (g / eq): 176-181, model: DEN-438;

[0065] 20 kg of aluminum oxide;

[0066] 40 kg of boron nitride;

[0067] 0.2 kg of silane coupling agent, the silane coupling agent being 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane;

[0068] Dispersant 0.1kg, brand name BYK-9076;

[0069] 2 kg of curing agent, brand name Aradur 5200;

[0070] 100 kg of toluene is used to mix the above raw materials evenly to obtain a high thermal conductivity adhesive.

[0071] The preparation process of modified thermally conductive carbon fiber includes the following steps:

[0072] Activation treatment: 3 mm long carbon fibers are immersed in an 8 g / L ammonium persulfate aqueous solution. The mass of carbon fibers added to each 1 L of ammonium persulfate aqueous solution is 18 g. The mixture is stirred for 15 min, filtered, rinsed with distilled water until the pH reaches 7, and dried to obtain activated carbon fibers.

[0073] For modification treatment, tetraethyl orthosilicate, ethanol, water, and hydrochloric acid were prepared in a molar ratio of 1:6.4:4:0.08. Tetraethyl orthosilicate and anhydrous ethanol were mixed evenly, and a mixture of deionized water and hydrochloric acid was added dropwise under stirring. After the addition was complete, the mixture was stirred and refluxed at 70°C for 2.5 h. After the sol cooled, 30% V / V N,N-dimethylformamide was added, and stirring was continued for 15 min to obtain silica sol. Activated carbon fibers were immersed in silica sol, stirred and mixed evenly, filtered, and dried to obtain modified thermally conductive carbon fibers.

[0074] Preparation Example 2

[0075] The difference from Preparation Example 1 is that the high thermal conductivity energy storage phase change microcapsules are prepared using the following steps:

[0076] Emulsification and dispersion: Mix 310g of No. 64 paraffin wax, 870g of deionized water and 95g of emulsifier, heat until the paraffin wax is completely melted, the emulsifier is Tween-80, stir and disperse evenly to obtain paraffin wax emulsion;

[0077] Paraffin loading: 980g of porous alumina was added to the paraffin emulsion. The porous alumina had a particle size of 35nm and a pore size range of 10-20nm. The mixture was ultrasonically vibrated for 8min and then filtered to obtain modified alumina particles.

[0078] Encapsulation process: Modified alumina particles and water were mixed evenly at a mass ratio of 1:18. Under nitrogen protection, 1500g of azobisisobutyramidine hydrochloride aqueous solution was added. The azobisisobutyramidine hydrochloride aqueous solution was composed of 10g of azobisisobutyramidine hydrochloride and 1490g of water. After heating to 57℃ and reacting for 9 hours, a core material solution was obtained. The core material solution, water, and anhydrous ethanol were mixed at a mass ratio of 1:2.5:8.5, and the pH was adjusted to 3.2. The mixture was heated to 60℃, and a mixture of tetraethyl orthosilicate and anhydrous ethanol was added. The mass ratio of core material dispersion, tetraethyl orthosilicate, and anhydrous ethanol was 1:0.42:2. The mixture was reacted for 6 hours, filtered, and dried to obtain pre-made microcapsules.

[0079] Thermal conductivity modification: High thermal conductivity adhesive is uniformly sprayed onto the surface of the pre-made microcapsules. The mass ratio of the pre-made microcapsules to the high thermal conductivity adhesive is 10:1. The microcapsules are heated to a semi-cured state at 82°C for 8 minutes to obtain semi-cured microcapsules. 500g of modified thermally conductive carbon fiber with an average length of 4mm is sprayed onto the surface of the semi-cured microcapsules. The microcapsules are then heated to 85°C and cured for 15 minutes to obtain high thermal conductivity energy storage phase change microcapsules.

[0080] Preparation Example 3

[0081] The difference from Preparation Example 1 is that the high thermal conductivity energy storage phase change microcapsules are prepared using the following steps:

[0082] Emulsification and dispersion: Mix 290g of No. 64 paraffin wax, 840g of deionized water and 88g of emulsifier, heat until the paraffin wax is completely melted, the emulsifier is Tween-80, stir and disperse evenly to obtain paraffin wax emulsion;

[0083] Loaded paraffin: 900g of porous alumina was added to the paraffin emulsion. The porous alumina had a particle size of 50nm and a pore size range of 10-20nm. The mixture was ultrasonically vibrated for 10min and then filtered to obtain modified alumina particles.

[0084] Encapsulation process: Modified alumina particles and water were mixed evenly at a mass ratio of 1:22. Under nitrogen protection, 1600g of azobisisobutyramidine hydrochloride aqueous solution was added. The azobisisobutyramidine hydrochloride aqueous solution was composed of 10g of azobisisobutyramidine hydrochloride and 1590g of water. After heating to 62℃ and reacting for 7h, the core material solution was obtained. The core material solution, water, and anhydrous ethanol were mixed at a mass ratio of 1:2.5:8.5, the pH was adjusted to 3, and the mixture was heated to 60℃. A mixture of tetraethyl orthosilicate and anhydrous ethanol was added. The mass ratio of the core material dispersion, tetraethyl orthosilicate, and anhydrous ethanol was 1:0.42:2. The mixture was reacted for 6h, filtered, and dried to obtain pre-made microcapsules.

[0085] Thermal conductivity modification: High thermal conductivity adhesive is uniformly sprayed onto the surface of the pre-made microcapsules. The mass ratio of the pre-made microcapsules to the high thermal conductivity adhesive is 10:1. The microcapsules are heated to a semi-cured state at 82°C for 8 minutes to obtain semi-cured microcapsules. 500g of modified thermally conductive carbon fiber with an average length of 4mm is sprayed onto the surface of the semi-cured microcapsules. The microcapsules are then heated to 85°C and cured for 15 minutes to obtain high thermal conductivity energy storage phase change microcapsules.

[0086] Preparation Example 4

[0087] The difference from Preparation Example 2 is that the raw materials for the high thermal conductivity adhesive include the following components in parts by weight:

[0088] 8 kg of bisphenol A type epoxy resin;

[0089] 6.5 kg of phenolic epoxy resin;

[0090] 28 kg of aluminum oxide;

[0091] 35 kg of boron nitride;

[0092] 0.3 kg of silane coupling agent;

[0093] Dispersant 0.3 kg;

[0094] 4 kg of curing agent;

[0095] 125 kg of toluene.

[0096] Preparation Example 5

[0097] The difference from Preparation Example 2 is that the raw materials for the high thermal conductivity adhesive include the following components in parts by weight:

[0098] 10 kg of bisphenol A type epoxy resin;

[0099] 5 kg of phenolic epoxy resin;

[0100] 35 kg of aluminum oxide;

[0101] 30 kg of boron nitride;

[0102] 0.4 kg of silane coupling agent;

[0103] Dispersant 0.5 kg;

[0104] 6 kg of curing agent;

[0105] 150 kg of toluene.

[0106] Preparation Example 6

[0107] The difference from Preparation Example 4 is that in the thermal conductivity modification step, the temperature to semi-curing is 85°C and the time is 7 minutes.

[0108] Preparation Example 7

[0109] The difference from Preparation Example 4 is that in the thermal conductivity modification step, the temperature to semi-curing is 88°C and the time is 6 minutes.

[0110] Preparation Example 8

[0111] The difference from Preparation Example 6 is that the mass ratio of the pre-made microcapsules to the high thermal conductivity adhesive is 10:1.5.

[0112] Preparation Example 9

[0113] The difference from Preparation Example 6 is that the mass ratio of the pre-made microcapsules to the high thermal conductivity adhesive is 10:2.

[0114] Preparation Example 10

[0115] The difference from Preparation Example 6 is that the mass ratio of the pre-made microcapsules to the high thermal conductivity adhesive is 10:0.5.

[0116] Preparation Example 11

[0117] The difference from Preparation Example 6 is that the mass ratio of the pre-made microcapsules to the high thermal conductivity adhesive is 10:3.

[0118] Comparative Preparation Example 1

[0119] The preparation process of energy storage phase change microcapsules includes the following steps: Weigh 110g of paraffin wax and 500mL of deionized water, mix and heat. After the paraffin wax is completely melted, add 1.6g of Tween-80 and emulsify using a high-speed emulsifier. Then place the mixture in a three-necked flask and heat it in a water bath at 68℃ for 15min to obtain a paraffin wax emulsion. Take 100g of melamine powder, an appropriate amount of 34% urea solution and an appropriate amount of deionized water into a three-necked flask, and add triethanolamine dropwise to adjust the pH of the system to 8. While stirring, raise the system temperature to 72℃ and keep it at 72℃ for 5min to obtain a urea-formaldehyde resin prepolymer. Add the paraffin wax emulsion dropwise to the urea-formaldehyde resin prepolymer while stirring and heating, and keep it at 62℃ for 50min. Discharge, filter, wash and dry to obtain energy storage phase change microcapsules.

[0120] Comparative Preparation Example 2

[0121] The difference from Preparation Example 1 is that the high thermal conductivity energy storage phase change microcapsules are prepared by the following steps:

[0122] Emulsification and dispersion: Mix 300g of No. 64 paraffin wax, 850g of deionized water and 90g of emulsifier, heat until the paraffin wax is completely melted, the emulsifier is Tween-80, stir and disperse evenly to obtain paraffin wax emulsion;

[0123] Paraffin loading: 950g of porous alumina was added to the paraffin emulsion. The porous alumina had a particle size of 40nm and a pore size range of 10-20nm. The mixture was ultrasonically vibrated for 6min and then filtered to obtain modified alumina particles.

[0124] Encapsulation process: Modified alumina particles and water were mixed evenly at a mass ratio of 1:20. Under nitrogen protection, 1510g of azobisisobutyramidine hydrochloride aqueous solution was added. The azobisisobutyramidine hydrochloride aqueous solution was composed of 10g of azobisisobutyramidine hydrochloride and 1500g of water. After heating to 60℃ and reacting for 8 hours, a core material solution was obtained. The core material solution, water, and anhydrous ethanol were mixed at a mass ratio of 1:2:8, and the pH was adjusted to 3. The mixture was heated to 59℃, and a mixture of tetraethyl orthosilicate and anhydrous ethanol was added. The mass ratio of the core material dispersion, tetraethyl orthosilicate, and anhydrous ethanol was 1:0.45:2. The mixture was reacted for 7 hours, filtered, and dried to obtain high thermal conductivity phase change microcapsules.

[0125] Comparative preparation example 3

[0126] The difference from Preparation Example 1 is that the high thermal conductivity adhesive was replaced with an equal mass of ordinary adhesive, the raw materials of which consist of the following components in parts by weight:

[0127] 13kg of bisphenol A type epoxy resin, model E44;

[0128] 0.2 kg of silane coupling agent, the silane coupling agent being 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane;

[0129] Dispersant 0.1kg, brand name BYK-9076;

[0130] 2 kg of curing agent, brand name Aradur 5200;

[0131] 100 kg of toluene is used to mix the above raw materials evenly to obtain a high thermal conductivity adhesive.

[0132] Comparative preparation example 4

[0133] The difference from Preparation Example 1 is that the modified thermally conductive carbon fiber was replaced with ordinary carbon fiber of equal length.

[0134] Example

[0135] Example 1

[0136] A high-strength concrete for airport pavement comprises the following components in parts by weight:

[0137] 320 kg of P.O42.5 grade low-alkali ordinary Portland cement;

[0138] 40 kg of Grade I fly ash;

[0139] 590 kg of sand, with a fineness modulus between 2.6 and 3.2 and a mud content of 2.1%;

[0140] 1400 kg of crushed stone;

[0141] 6 kg of water-reducing agent, using GH-6 type pavement concrete retarding high-efficiency water-reducing and air-entraining agent produced by Beijing Port and Shipping Jinxing Technology Development Co., Ltd.

[0142] 125kg of water;

[0143] Two kg of high thermal conductivity energy storage phase change microcapsules were prepared from Preparation Example 1.

[0144] The preparation process of high-strength concrete for airport pavement includes the following steps:

[0145] Step 1: Mix the crushed stone and sand evenly to obtain an aggregate mixture;

[0146] Step 2: Mix cement, fly ash and high thermal conductivity energy storage phase change microcapsules evenly to obtain a mixture;

[0147] Step 3: Mix water and water-reducing agent evenly to obtain a water-reducing agent solution;

[0148] Step four: Mix the admixture solution, aggregate mixture and aggregate evenly to obtain high-strength concrete for airport pavement.

[0149] Example 2-11

[0150] The difference from Example 1 is that the high thermal conductivity energy storage phase change microcapsules were prepared sequentially from Preparation Examples 2-11.

[0151] Example 12

[0152] The difference from Example 8 is that the raw materials for the high-strength concrete for airport pavement include the following components in parts by weight: 330 kg of P.O42.5 grade low-alkali ordinary Portland cement;

[0153] 30 kg of Grade I fly ash;

[0154] Sand 600kg;

[0155] 1390 kg of crushed stone;

[0156] 6.5 kg of water-reducing agent;

[0157] 130kg of water;

[0158] 2kg of high thermal conductivity energy storage phase change microcapsules.

[0159] Example 13

[0160] The difference from Example 8 is that the raw materials for the high-strength concrete for airport pavement include the following components in parts by weight: 340 kg of P.O42.5 grade low-alkali ordinary Portland cement;

[0161] 20 kg of Grade I fly ash;

[0162] Sand 610kg;

[0163] 1380 kg of crushed stone;

[0164] 7 kg of water-reducing agent;

[0165] Water 140kg;

[0166] 2kg of high thermal conductivity energy storage phase change microcapsules.

[0167] Example 14

[0168] The difference from Example 12 is that the weight of the high thermal conductivity energy storage phase change microcapsule is 3 kg.

[0169] Example 15

[0170] The difference from Example 12 is that the weight of the high thermal conductivity energy storage phase change microcapsule is 4 kg.

[0171] Comparative Example

[0172] Comparative Example 1

[0173] The difference from Example 1 is that the high thermal conductivity energy storage phase change microcapsules are replaced with an equal mass of energy storage phase change microcapsules prepared by Comparative Preparation Example 1.

[0174] Comparative Examples 2-4

[0175] The difference from Example 1 is that the high thermal conductivity energy storage phase change microcapsules were prepared sequentially from Comparative Preparation Examples 2-4.

[0176] Comparative Example 5

[0177] The difference from Example 1 is that no high thermal conductivity energy storage phase change microcapsules were added.

[0178] Performance testing

[0179] Test methods

[0180] (1) Number of freeze-thaw cycles for cracks: Take concrete from Examples 1-15 and Comparative Examples 1-5, prepare cubic specimens with a side length of 150 mm under the same conditions, and conduct freeze-thaw cycle tests in accordance with GB / T50085-2009 Test Method for Long-term Performance and Durability of Ordinary Concrete. Record the number of freeze-thaw cycles corresponding to the appearance of visible cracks on the surface of the specimens. The test results are shown in Table 1.

[0181] (2) Compressive strength: The compressive strength of concrete in Examples 1-15 and Comparative Examples 1-5 was tested according to GB / T 50081-2019 Test Method for Physical and Mechanical Properties of Concrete. The test results are shown in Table 1.

[0182] (3) Flexural tensile strength: The flexural tensile strength of concrete in Examples 1-15 and Comparative Examples 1-5 was tested according to the T0558-2005 Test Method for Flexural Tensile Strength of Cement Concrete. The test results are shown in Table 1.

[0183] Table 1. Test results of Examples 1-15 and Comparative Examples 1-5

[0184]

[0185]

[0186] Combining Examples 1-15 and Comparative Examples 1-5 with Table 1, it can be seen that Comparative Example 1, based on Comparative Example 5, added ordinary energy storage phase change microcapsules, resulting in an increase in the number of freeze-thaw cycles with cracks, but a decrease in compressive strength and flexural strength. This may be because, although ordinary paraffin energy storage phase change microcapsules can reduce cracks in concrete caused by excessive temperature differences, their low structural strength reduces the structural strength of the concrete. Comparative Example 2 added high thermal conductivity energy storage phase change microcapsules with porous alumina and silica shells, resulting in an increase in the number of freeze-thaw cycles with cracks, compressive strength, and flexural strength. This may be because the porous alumina and silica shells improve the sealing and structural strength of the high thermal conductivity energy storage phase change microcapsules, thereby increasing the strength of the concrete. Examples 1-3 and... Compared to Comparative Example 2, the number of freeze-thaw cycles with cracks, compressive strength, and flexural strength were significantly increased. Compared to Example 1, Comparative Example 3 showed a decrease in the number of freeze-thaw cycles with cracks, compressive strength, and flexural strength after replacing the high thermal conductivity adhesive with ordinary adhesive. Compared to Example 1, Comparative Example 4 showed a decrease in the number of freeze-thaw cycles with cracks, compressive strength, and flexural strength after replacing the modified thermally conductive carbon fiber with ordinary carbon fiber. This may be because the modified thermally conductive carbon fiber can form a three-dimensional thermally conductive network inside the concrete. The high thermal conductivity adhesive and the modified thermally conductive carbon fiber are conducive to the heat transfer of the high thermal conductivity energy storage phase change microcapsules, reducing cracks caused by excessive temperature differences in the concrete. The modified thermally conductive carbon fiber plays a reinforcing role inside the concrete, improving the mechanical properties of the concrete and reducing cracking.

[0187] Examples 4-5 showed changes in the proportion of the high thermal conductivity adhesive, resulting in changes in the number of freeze-thaw cycles, compressive strength, and flexural tensile strength. Example 4 showed better results, indicating that the proportion of the high thermal conductivity adhesive affects the temperature crack resistance and mechanical properties of concrete.

[0188] Examples 6-7 changed the semi-curing temperature and time, and the number of freeze-thaw cycles, compressive strength and flexural tensile strength of the concrete were slightly improved. Among them, Example 6 showed better results, indicating that the parameters of the semi-curing step can affect the temperature crack resistance and mechanical properties of concrete.

[0189] Examples 8-9 changed the mass ratio of pre-formed microcapsules to high thermal conductivity adhesive, resulting in a slight increase in the number of freeze-thaw cycles, compressive strength, and flexural strength. Among them, Example 8 showed better results. In Example 10, the amount of high thermal conductivity adhesive was too small, while in Example 11, the amount of high thermal conductivity adhesive was too large, resulting in a slight decrease in the number of freeze-thaw cycles, compressive strength, and flexural strength. This indicates that the preferred mass ratio of pre-formed microcapsules to high thermal conductivity adhesive is 10:(1-2).

[0190] Examples 12-13 altered the concrete mix proportions, resulting in changes in the number of freeze-thaw cycles, compressive strength, and flexural strength. Example 12 showed better results, indicating that the mix proportions of Example 12 are preferred. Examples 14-15 progressively increased the amount of high thermal conductivity energy storage phase change microcapsules, resulting in a gradual increase in the number of freeze-thaw cycles, and a first increase followed by a decrease in compressive strength and flexural strength. Therefore, Example 14 showed better results.

[0191] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-strength concrete for airport pavements, characterized by: The raw materials include the following components in parts by weight: cement 320-340 parts; fly ash 20-40 parts; sand 590-610 parts; gravel 1380-1400 parts; water reducing agent 6-7 parts; water 125-140 parts; high thermal conductivity energy storage phase change microcapsule 2-4 parts; The preparation process of the high thermal conductivity energy storage phase change microcapsule includes the following steps: Emulsification and dispersion: mix and heat paraffin, water and emulsifier, emulsify and disperse to obtain paraffin emulsion; Loading paraffin: add porous alumina to the paraffin emulsion, ultrasonic oscillation, solid-liquid separation, to obtain modified alumina particles; Coating treatment: mix the modified alumina particles with water uniformly, add azobisdimethylamidine hydrochloride aqueous solution under inert gas protection, heat reaction to obtain core material liquid, mix the core material liquid, water, anhydrous ethanol and pH adjuster, control the pH to be acidic, heat, continue to add the mixture of tetraethyl orthosilicate and anhydrous ethanol, mix and react, solid-liquid separation, dry to obtain pre-made microcapsule; Thermal conductivity modification: uniformly spray high thermal conductivity glue to the surface of the pre-made microcapsule, heat to semi-cured state to obtain semi-cured microcapsule, spray modified thermal conductivity carbon fiber to the surface of the semi-cured microcapsule, heat and cure to obtain high thermal conductivity energy storage phase change microcapsule; The mass ratio of the pre-made microcapsule to the high thermal conductivity glue is 10: (1-2); The raw materials of the high thermal conductivity glue include the following components in parts by weight: Bisphenol A type epoxy resin 5-10 parts; phenolic epoxy resin 5-8 parts; alumina 20-35 parts; boron nitride 30-40 parts; silane coupling agent 0.2-0.4 parts; dispersant 0.1-0.5 parts; curing agent 2-6 parts; solvent 100-150 parts; The preparation process of the modified thermal conductivity carbon fiber includes the following steps: Activation treatment: add carbon fiber to ammonium persulfate aqueous solution, stir and react, solid-liquid separation, wash with water, dry to obtain activated carbon fiber; modification treatment: add the activated carbon fiber to silica sol, mix uniformly, solid-liquid separation, dry to obtain modified thermal conductivity carbon fiber; The length of the modified thermal conductivity carbon fiber is 3-5 mm; The mass concentration of the ammonium persulfate aqueous solution is 8-12 g / L.

2. The high-strength concrete for airport pavement according to claim 1, characterized by: In the thermal conductivity modification step, the temperature for heating to semi-cured state is 82-88℃, and the time is 6-8 min.

3. Process for the production of high-strength concrete for airport pavements according to any one of claims 1-2, characterized in that: The following steps are included: Step one: mix gravel and sand uniformly to obtain aggregate mixture; Step two: mix cement, fly ash and high thermal conductivity energy storage phase change microcapsule uniformly to obtain mixture; Step three: mix water and water reducing agent uniformly to obtain water reducing agent solution; Step four: mix the water reducing agent solution, aggregate mixture and mixture uniformly to obtain high strength concrete for airport runway pavement.

Images