Preparation method of normal-temperature mixed asphalt concrete

Abstract

The invention belongs to the technical field of light building materials, and particularly relates to a preparation method of normal-temperature mixed asphalt concrete. The preparation method of the normal-temperature mixed asphalt concrete comprises the following steps: uniformly mixing 90-100 parts by weight of aggregate, 10-20 parts by weight of limestone mineral powder and 6-12 parts by weight of a fiber material at room temperature, then adding 2-4 parts by weight of a polycarboxylic acid water reducer and 1-5 parts by weight of water, stirring for 20-30 minutes, then adding 20-30 parts by weight of carboxylated cationic emulsified asphalt, and stirring at normal temperature to obtain a mixture; and pouring the mixture to obtain the normal-temperature mixed asphalt concrete. According to the invention, the dynamic stability is effectively improved while good splitting strength is ensured, and the method can be applied to light building materials.

Description

Technical Field

[0001] This invention belongs to the field of lightweight building materials technology, specifically relating to a method for preparing asphalt concrete by mixing at room temperature. Background Technology

[0002] Ambient temperature mixed asphalt concrete is an asphalt mixture that is mixed, laid, and compacted at ambient temperature. It eliminates the need to heat the asphalt and aggregates, significantly reducing energy consumption and pollution, and can be effectively applied in the field of lightweight building materials. Its core relies on emulsified or diluted asphalt as a binder, making it suitable for low-traffic roads, temporary pavements, or repair projects. The core of ambient temperature mixed asphalt concrete lies in emulsified asphalt technology.

[0003] The advantages of ambient temperature mixing asphalt concrete are as follows: (1) No need to heat aggregates and asphalt at high temperature, greatly reducing energy consumption; no high temperature smoke emission during construction, reducing harmful gas and dust pollution; (2) Mixing and paving can be carried out at ambient temperature, without being limited by temperature and season, and can be carried out on rainy days and in winter; no need for large heating equipment, small machinery or even manual operation is required; (3) Reduce fuel consumption and equipment investment, and can utilize recycled materials from old asphalt pavement, reducing raw material costs and post-maintenance costs; (4) Cold-mixed asphalt mixtures can be produced in advance, have a long sealed storage time, and do not require insulation measures during transportation.

[0004] Chinese patent (publication number CN113831081B) discloses an asphalt / cement composite base room temperature self-compacting asphalt concrete and its preparation method. The components and their weight percentages include: 10-20 parts emulsified asphalt, 4-12 parts cement, 40-73 parts aggregate, 12-23 parts mineral powder, 1-3 parts bonding agent, and 1-5 parts water. This invention optimizes the asphalt concrete formula and gradation composition, resulting in concrete that can be mixed and laid at room temperature, exhibiting advantages such as high early strength. Therefore, it is crucial to screen the components of asphalt concrete, select suitable materials to replace cement, and combine it with self-compacting technology (without the need for compaction machinery). However, this asphalt concrete requires the addition of cement, which easily leads to shrinkage deformation and cracking, and its dynamic stability also needs improvement.

[0005] The use of aggregates, emulsified asphalt, and other components to prepare asphalt concrete through room temperature mixing has become a research direction that can effectively improve dynamic stability while ensuring good splitting strength and can be applied to lightweight building materials. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing room-temperature mixed asphalt concrete. This invention uses oleic acid, maleic anhydride, and styrene as raw materials, combined with triethylenetetramine to prepare carboxylated cationic emulsified asphalt. Furthermore, it employs activated fiber composite materials to replace traditional cement, and combines these with aggregates, limestone powder, and other components to prepare room-temperature mixed asphalt concrete. This method achieves excellent splitting resistance and dynamic stability without the use of cement, and can be effectively applied to lightweight building materials.

[0007] In a first aspect, the present invention provides a method for preparing asphalt concrete by mixing at room temperature, comprising the following steps: By weight, 90-100 parts of aggregate, 10-20 parts of limestone powder and 6-12 parts of fiber material are mixed evenly at room temperature. Then, 2-4 parts of polycarboxylate superplasticizer and 1-5 parts of water are added and stirred for 20-30 minutes. Then, 20-30 parts of carboxylated cationic emulsified asphalt are added and mixed at room temperature to obtain a mixture. The mixture is then poured to obtain room temperature mixed asphalt concrete.

[0008] As a preferred embodiment of the present invention, the weight fraction of the aggregate may be 90 parts, 92 parts, 94 parts, 96 parts, 98 parts, or 100 parts, etc.

[0009] As a preferred embodiment of the present invention, the weight parts of the limestone powder may be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts, etc.

[0010] As a preferred embodiment of the present invention, the weight parts of the fiber material may be 6, 7, 8, 9, 10, 11 or 12 parts, etc.

[0011] As a preferred embodiment of the present invention, the polycarboxylate superplasticizer may be present in parts by weight of 2, 2.5, 3, 3.5, or 4, etc.

[0012] As a preferred embodiment of the present invention, the weight parts of the carboxylated cationic emulsified asphalt can be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, or 30 parts, etc.

[0013] As a preferred technical solution of the present invention, the preparation method of the carboxylated cationic emulsified asphalt is as follows: a copolymer is prepared using oleic acid, maleic anhydride and styrene as raw materials, then triethylenetetramine is added to the copolymer to prepare an intermediate, the intermediate is then subjected to dehydration and cyclization treatment to obtain a carboxylated cationic emulsifier, and finally the carboxylated cationic emulsifier and asphalt are used as raw materials for emulsification treatment to obtain carboxylated cationic emulsified asphalt.

[0014] The carboxylated cationic emulsified asphalt of this invention uses oleic acid, maleic anhydride, and styrene as raw materials. An oleic acid-maleic anhydride-styrene terpolymer is obtained by catalysis of 3-mercaptopropionic acid and cumene hydroperoxide. Triethylenetetramine is then added to the copolymer to obtain an amide intermediate. The amidation intermediate is subjected to high-temperature dehydration and cyclization treatment to form a carboxylated cationic emulsifier. The carboxylated cationic emulsifier is then used as a raw material to emulsify asphalt to obtain carboxylated cationic emulsified asphalt.

[0015] As a preferred embodiment of the present invention, the preparation steps of the intermediate are as follows: by weight, 30-36 parts of oleic acid and 6-8 parts of maleic anhydride are stirred and heated to 120-130°C under a nitrogen atmosphere, and then 4-6 parts of styrene, 0.02-0.04 parts of cumene hydroperoxide and 0.02-0.04 parts of 3-mercaptopropionic acid are added dropwise, and the mixture is stirred and reacted for 2-4 hours to obtain a copolymer. Then, 30-34 parts of triethylenetetramine are added to the copolymer and reacted at 150-160°C for 2-4 hours to obtain the intermediate.

[0016] As a preferred technical solution of the present invention, the conditions for the dehydration and cyclization treatment are: temperature of 200~220℃ and time of 30~40min.

[0017] As a preferred embodiment of the present invention, the emulsification process is as follows: 1.0 to 1.2 parts of carboxylated cationic emulsifier are added to 30 to 40 parts of deionized water at 70 to 80°C, and the pH is adjusted to 2 to 4 to obtain a soap solution. 50 to 60 parts of asphalt are heated to 120 to 130°C, and then mixed with the soap solution and added to a colloid mill for grinding for 6 to 8 minutes to obtain carboxylated cationic emulsified asphalt.

[0018] The carboxylated cationic emulsified asphalt of the present invention contains carboxyl groups, which can dissociate and form ionic coordination bonds with metal cations on the aggregate surface, effectively strengthening interfacial adhesion, improving the interfacial bond strength between asphalt and aggregate, inhibiting fatigue crack initiation, and increasing fatigue life; at the same time, the benzene ring in the carboxylated cationic emulsified asphalt is a planar rigid structure, and its conjugated π bonds endow the molecular chain with high mechanical strength, reducing the deformation of the material under stress, thereby obtaining good splitting strength.

[0019] As a preferred embodiment of the present invention, the fiber material is an activated fiber composite material; The preparation method of the activated fiber composite material includes: activating alumina fibers with calcium hydroxide suspension to obtain the activated fiber composite material.

[0020] As a preferred embodiment of the present invention, the activation treatment step is as follows: immersing alumina fibers in a 1 mol / L calcium hydroxide suspension for 4-6 hours, then drying at 100-110°C for 50-60 minutes, and finally activating at 200-240°C for 120-160 minutes to obtain an activated fiber composite material.

[0021] As a preferred embodiment of the present invention, the alumina fiber is Dongheng Guoxian's 72-F alumina fiber, with a chemical composition of alumina to silicon dioxide mass ratio of 72:28 and a density of 3.1 g / cm³. 3 The average fiber diameter is 5.5-7.5μm, and the impurity content is <0.5%.

[0022] This invention uses 72-F alumina fiber containing Dongheng Guoxian for activation treatment. The alumina fiber has a high silica content, and the activation effect is better when using calcium hydroxide suspension. By stimulating the potential activity of alumina and silica in the fiber, the hydration reaction is promoted to obtain activated fiber composite material.

[0023] The activated fiber composite material of the present invention achieves the function of replacing cement by hydrating calcium ions provided in calcium hydroxide suspension with activated alumina and silica to form CSH gel. At the same time, the CSH gel in the activated fiber composite material contains hydroxyl groups, which can combine with carboxylated cationic emulsified asphalt containing carboxyl groups to strengthen the interfacial connection. The CSH gel can also fill the interfacial voids and play a bonding role between different materials, thereby effectively improving splitting strength and dynamic stability.

[0024] As a preferred embodiment of the present invention, the aggregate is limestone crushed stone and steel slag; The mass ratio of the limestone crushed stone to the steel slag is (1~2):1.

[0025] As a preferred embodiment of the present invention, the limestone crushed stone has a particle size of 5-10 mm, an abrasion loss of 11-12%, and an apparent relative density of 2.7-2.8 g / cm³. 3 The water absorption rate is 0.5~0.6%.

[0026] As a preferred embodiment of the present invention, the steel slag has a particle size of 9-16 mm and an apparent relative density of 3.5-3.7 g / cm³. 3 The content of needle-like and flaky particles (>9.5mm) is 4.8~5.0%, the crushing value is 13~14%, and the abrasion loss is 16~18%.

[0027] This invention uses limestone crushed stone and steel slag as composite aggregates. The steel slag can form a rigid skeleton structure, which significantly improves the deformation resistance of asphalt concrete. At the same time, the needle-like structure can increase the contact area with asphalt and improve the interfacial mechanical interlocking. As an alkaline aggregate, limestone crushed stone has a strong electrostatic adsorption effect with carboxylated cationic emulsified asphalt. At the same time, its small particle size can fill the voids in the steel slag skeleton, reduce the porosity of the mixture, and reduce stress concentration points. By controlling the mass ratio of limestone crushed stone to steel slag, the splitting resistance of asphalt concrete is effectively improved and good dynamic stability is obtained.

[0028] As a preferred embodiment of the present invention, the apparent density of the limestone powder is 2.6~2.7 g / cm³. 3 The hydrophilicity coefficient is 0.8~0.9, with 100% for particle size less than 0.6mm, 92~94% for particle size less than 0.15mm, and 80~82% for particle size less than 0.075mm.

[0029] The limestone powder used in this invention has a particle size range of less than 0.075mm, accounting for 80-82%, which can fill the tiny gaps between aggregates, enabling the asphalt concrete to form a continuous dense-graded structure. The dense structure reduces the point contact stress concentration between aggregate particles, making the load distribution more uniform.

[0030] As a preferred embodiment of the present invention, the polycarboxylate superplasticizer is selected from one or more of Subote PCA-I, Subote PCA-VIII, or Subote PCA-9.

[0031] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses oleic acid, maleic anhydride and styrene as raw materials to prepare carboxylated cationic emulsified asphalt, which contains active carboxyl groups. It can form ionic coordination bonds with metal cations on the surface of compound aggregates to improve the interfacial bonding strength between asphalt and aggregates, and can also combine with hydroxyl groups in activated fiber composite CSH gel to strengthen the interfacial connection. Through the synergistic effect of each component, the performance of asphalt concrete is effectively improved and it can be applied to lightweight building materials.

[0032] (2) The carboxylated cationic emulsified asphalt of the present invention contains carboxyl groups. The carboxyl groups can dissociate and form ionic coordination bonds with metal cations on the surface of aggregates, effectively strengthening interfacial adhesion, improving the interfacial adhesion strength between asphalt and aggregates, inhibiting fatigue crack initiation, and increasing fatigue life. At the same time, the benzene ring in the carboxylated cationic emulsified asphalt is a planar rigid structure, and its conjugated π bonds endow the molecular chain with high mechanical strength, reducing the deformation of the material under stress, thereby obtaining good splitting strength.

[0033] (3) The activated fiber composite material of the present invention forms CSH gel by hydration of calcium ions provided in calcium hydroxide suspension with activated alumina and silica, thereby achieving the function of replacing cement; at the same time, the CSH gel in the activated fiber composite material contains hydroxyl groups, which can combine with carboxylated cationic emulsified asphalt containing carboxyl groups to strengthen the interface connection. The CSH gel can also fill the interface gaps and play a bonding role between different materials, thereby effectively improving the splitting strength and dynamic stability.

[0034] (4) This invention uses limestone crushed stone and steel slag as composite aggregates. The steel slag can form a rigid skeleton structure, which significantly improves the deformation resistance of asphalt concrete. At the same time, the needle-like structure can increase the contact area with asphalt and improve the interfacial mechanical interlocking effect. As an alkaline aggregate, limestone crushed stone has a strong electrostatic adsorption effect with carboxylated cationic emulsified asphalt. At the same time, its small particle size can fill the voids in the steel slag skeleton, reduce the porosity of the mixture, and reduce stress concentration points. By controlling the mass ratio of limestone crushed stone to steel slag, the splitting resistance of asphalt concrete can be effectively improved and good dynamic stability can be obtained. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0036] Figure 1 This is a schematic diagram of the preparation of the copolymer in Example 1.

[0037] Figure 2 This is a schematic diagram of the preparation of the intermediate in Example 1.

[0038] Figure 3 This is a schematic diagram illustrating the preparation of the carboxylated cationic emulsifier in Example 1.

[0039] Figure 4 The image shows a splitting test result of the sample in Example 1. Detailed Implementation

[0040] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0041] The sources of some components in the examples and comparative examples are as follows: Limestone crushed stone: particle size 5~10mm, abrasion loss 11.23%, apparent relative density 2.746g / cm3, water absorption rate 0.6%; Steel slag: Particle size 9~16mm, apparent relative density 3.68g / cm3, needle-like and flaky content (>9.5mm) 4.82%, crushing value 13.4%, abrasion loss 16.9%, sourced from Shanghai Baoshan Iron & Steel Co., Ltd. The commercially available cationic emulsified asphalt, model HY-216, was purchased from Hebei Huayun Hongye Chemical Co., Ltd. Commercially available asphalt, product number WB93918, was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd. Oleic acid, CAS No. 112-80-1, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Maleic anhydride, CAS No. 108-31-6, was purchased from Sinopharm Chemical Reagent Co., Ltd. Styrene, CAS No. 100-42-5, purchased from Sinopharm Chemical Reagent Co., Ltd. Cumene hydroperoxide, CAS No. 80-15-9, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. 3-Mercaptopropionic acid, CAS No. 107-96-0, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Triethylenetetramine, CAS No. 112-24-3, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Limestone powder with an apparent density of 2.689 g / cm3, a hydrophilicity coefficient of 0.82, and a particle size range of 100% less than 0.6 mm, 92.1% less than 0.15 mm, and 80.5% less than 0.075 mm was purchased from Yangyuan Longyang Calcium Industry Co., Ltd. Alumina fiber A, Dongheng Guoxian's 72-F alumina fiber, has a chemical composition of alumina to silicon dioxide mass ratio of 72:28, a density of 3.1 g / cm3, an average fiber diameter of 5.5~7.5 μm, and impurity content <0.5%. It was purchased from Shandong Dongheng Guoxian New Material Co., Ltd. Alumina fiber B, Dongheng Guoxian's 95-M alumina fiber, has a chemical composition of alumina to silicon dioxide mass ratio of 95:5, a density of 2.8 g / cm3, an average fiber diameter of 3~4 μm, and impurity content <0.5%.

[0042] Example 1 This embodiment provides a method for preparing asphalt concrete at room temperature, including the following steps: By weight, 100 parts of aggregate (50 parts of limestone crushed stone and 50 parts of steel slag), 20 parts of limestone mineral powder and 12 parts of activated fiber composite material are mixed evenly at room temperature. Then, 4 parts of Subote PCA-I polycarboxylate superplasticizer and 5 parts of water are added and stirred for 30 minutes. Then, 30 parts of carboxylated cationic emulsified asphalt are added and mixed at room temperature to obtain a mixture. The mixture is then poured to obtain room temperature mixed asphalt concrete.

[0043] Preparation of the carboxylated cationic emulsified asphalt: In a nitrogen atmosphere, 36 parts by weight of oleic acid and 8 parts by weight of maleic anhydride were stirred and heated to 130°C. Then, 6 parts by weight of styrene, 0.04 parts by weight of cumene hydroperoxide and 0.04 parts by weight of 3-mercaptopropionic acid were added dropwise, and the mixture was stirred for 4 hours to obtain a copolymer. Then, 34 parts by weight of triethylenetetramine were added to the copolymer and reacted at 160°C for 2 hours to obtain an intermediate. The intermediate was then subjected to dehydration and cyclization treatment (temperature 220°C, time 30 min) to obtain a carboxylated cationic emulsifier. 1.2 parts by weight of the carboxylated cationic emulsifier were added to 40 parts by weight of deionized water at 80°C to adjust the pH to 4 and obtain a soap solution. 60 parts by weight of asphalt were heated to 130°C and mixed with the soap solution. The mixture was then ground in a colloid mill for 8 min to obtain the carboxylated cationic emulsified asphalt. Preparation of activated fiber composite material: Alumina fiber A (Dongheng Guoxian's 72-F alumina fiber) was soaked in 1 mol / L calcium hydroxide suspension for 6 h, then dried at 110 °C for 50 min, and finally activated at 240 °C for 1200 min to obtain activated fiber composite material.

[0044] Example 2 This embodiment provides a method for preparing asphalt concrete at room temperature, including the following steps: By weight, 90 parts of aggregate (60 parts of limestone crushed stone and 30 parts of steel slag), 10 parts of limestone mineral powder and 6 parts of activated fiber composite material are mixed evenly at room temperature. Then, 2 parts of Subote PCA-VIII polycarboxylate superplasticizer and 1 part of water are added and stirred for 20 minutes. Then, 20 parts of carboxylated cationic emulsified asphalt are added and mixed at room temperature to obtain a mixture. The mixture is then poured to obtain room temperature mixed asphalt concrete.

[0045] Preparation of the carboxylated cationic emulsified asphalt: In a nitrogen atmosphere, 30 parts by weight of oleic acid and 6 parts by weight of maleic anhydride were stirred and heated to 120°C. Then, 4 parts by weight of styrene, 0.02 parts by weight of cumene hydroperoxide and 0.02 parts by weight of 3-mercaptopropionic acid were added dropwise, and the mixture was stirred for 2 hours to obtain a copolymer. Then, 30 parts by weight of triethylenetetramine were added to the copolymer and reacted at 150°C for 4 hours to obtain an intermediate. The intermediate was then subjected to dehydration and cyclization treatment (at 200°C for 40 minutes) to obtain a carboxylated cationic emulsifier. 1.0 part by weight of the carboxylated cationic emulsifier was added to 30 parts by weight of deionized water at 70°C, and the pH was adjusted to 2 to obtain a soap solution. 50 parts by weight of asphalt were heated to 120°C and mixed with the soap solution. The mixture was then ground in a colloid mill for 8 minutes to obtain the carboxylated cationic emulsified asphalt. Preparation of activated fiber composite material: Alumina fiber A (Dongheng Guoxian's 72-F alumina fiber) was soaked in 1 mol / L calcium hydroxide suspension for 4 h, then dried at 100 °C for 60 min, and finally activated at 200 °C for 160 min to obtain activated fiber composite material.

[0046] Example 3 This embodiment provides a method for preparing asphalt concrete at room temperature, including the following steps: By weight, 95 parts of aggregate (50 parts of limestone crushed stone and 45 parts of steel slag), 15 parts of limestone mineral powder and 9 parts of activated fiber composite material are mixed evenly at room temperature. Then, 3 parts of Subote PCA-9 polycarboxylate superplasticizer and 3 parts of water are added and stirred for 25 minutes. Then, 25 parts of carboxylated cationic emulsified asphalt are added and mixed at room temperature to obtain a mixture. The mixture is then poured to obtain room temperature mixed asphalt concrete.

[0047] Preparation of the carboxylated cationic emulsified asphalt: In a nitrogen atmosphere, 33 parts oleic acid and 7 parts maleic anhydride were stirred and heated to 125°C. Then, 5 parts styrene, 0.03 parts cumene hydroperoxide, and 0.03 parts 3-mercaptopropionic acid were added dropwise, and the mixture was stirred for 3 hours to obtain a copolymer. Then, 32 parts triethylenetetramine were added to the copolymer and reacted at 155°C for 3 hours to obtain an intermediate. The intermediate was then subjected to dehydration and cyclization treatment (temperature 210°C, time 35 min) to obtain a carboxylated cationic emulsifier. 1.1 parts of the carboxylated cationic emulsifier were added to 35 parts deionized water at 75°C, and the pH was adjusted to 3 to obtain a soap solution. 55 parts asphalt were heated to 125°C and mixed with the soap solution. The mixture was then ground in a colloid mill for 7 min to obtain the carboxylated cationic emulsified asphalt. Preparation of activated fiber composite material: Alumina fiber A (Dongheng Guoxian's 72-F alumina fiber) was soaked in 1 mol / L calcium hydroxide suspension for 5 h, then dried at 105 °C for 55 min, and finally activated at 220 °C for 140 min to obtain activated fiber composite material.

[0048] Comparative Example 1 The difference between this comparative example and Example 1 is that all 100 portions of aggregate used were crushed limestone.

[0049] Comparative Example 2 The difference between this comparative example and Example 1 is that steel slag was used in all 100 portions of aggregate.

[0050] Comparative Example 3 The difference between this comparative example and Example 1 is that a commercially available cationic emulsified asphalt (model HY-216) was used instead of carboxylated cationic emulsified asphalt.

[0051] Comparative Example 4 The difference between this comparative example and Example 1 is that alumina fiber B is used instead of alumina fiber A in the preparation of the activated fiber composite material.

[0052] The performance of the asphalt concrete provided in the above embodiments and comparative examples was tested using the following methods: (1) Splitting test: The splitting test was carried out on the samples of the examples and comparative examples using the multi-functional fully automatic asphalt pressure tester SYD-0730A of Zhentong Company. The sample was placed in the clamp of the test instrument. There are arc-shaped pressure strips installed at the top and bottom of the instrument. The upper and lower pressure strips should be centered and parallel. After the sample was placed, the test instrument was started so that the pressure head of the instrument contacted the upper and lower pressure strips. A force perpendicular to the pressure strips was applied to the specimen at a specified loading rate of 50 mm / min to obtain the splitting strength and failure load.

[0053] (2) Dynamic stability and fatigue life: The dynamic stability and fatigue resistance of the samples of the examples and comparative examples were tested in accordance with the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering (JTGE20-2011).

[0054] The performance test data above are shown in Table 1.

[0055] Table 1 Performance Test Results ; As can be seen from the above, the present invention uses oleic acid, maleic anhydride and styrene as raw materials, and triethylenetetramine to prepare carboxylated cationic emulsified asphalt. It also uses activated fiber composite material to replace traditional cement, and combines aggregates, limestone powder and other components to prepare room temperature mixed asphalt concrete (Examples 1 to 3), which has better comprehensive performance.

[0056] Compared to Example 1, the 100 parts of aggregate used entirely limestone crushed stone, lacking the rigid skeleton structure and mechanical interlocking effect of steel slag, resulting in poorer splitting resistance and reduced dynamic stability of the asphalt concrete (Comparative Example 1); compared to Example 1, the 100 parts of aggregate used entirely steel slag, lacking the use of alkaline aggregate limestone crushed stone, resulting in poorer splitting resistance and reduced dynamic stability of the asphalt concrete (Comparative Example 2); compared to Example 1, the use of commercially available cationic emulsified asphalt (model HY-216) instead of carboxylated cationic emulsified asphalt resulted in poorer splitting resistance and reduced dynamic stability of the asphalt concrete (Comparative Example 3); compared to Example 1, the use of alumina fiber B instead of alumina fiber A in the preparation of activated fiber composite material resulted in poor activation effect due to the low silica content of alumina fiber B (Comparative Example 4).

Claims

1. A method for preparing asphalt concrete at room temperature, characterized in that, Includes the following steps: By weight, 90-100 parts of aggregate, 10-20 parts of limestone powder and 6-12 parts of fiber material are mixed evenly at room temperature. Then, 2-4 parts of polycarboxylate superplasticizer and 1-5 parts of water are added and stirred for 20-30 minutes. Then, 20-30 parts of carboxylated cationic emulsified asphalt are added and mixed at room temperature to obtain a mixture. The mixture is then poured to obtain room temperature mixed asphalt concrete. The method for preparing the carboxylated cationic emulsified asphalt is as follows: a copolymer is prepared using oleic acid, maleic anhydride and styrene as raw materials, then triethylenetetramine is added to the copolymer to prepare an intermediate, the intermediate is then dehydrated and cyclized to obtain a carboxylated cationic emulsifier, and finally the carboxylated cationic emulsifier and asphalt are used as raw materials for emulsification to obtain carboxylated cationic emulsified asphalt.

2. The method for preparing asphalt concrete at room temperature according to claim 1, characterized in that, The preparation steps of the intermediate are as follows: by weight, 30-36 parts of oleic acid and 6-8 parts of maleic anhydride are stirred and heated to 120-130°C under a nitrogen atmosphere, and then 4-6 parts of styrene, 0.02-0.04 parts of cumene hydroperoxide and 0.02-0.04 parts of 3-mercaptopropionic acid are added dropwise. The mixture is stirred and reacted for 2-4 hours to obtain a copolymer. Then, 30-34 parts of triethylenetetramine are added to the copolymer and reacted at 150-160°C for 2-4 hours to obtain the intermediate.

3. The method for preparing asphalt concrete at room temperature according to claim 1, characterized in that, The emulsification process is as follows: 1.0 to 1.2 parts of carboxylated cationic emulsifier are added to 30 to 40 parts of deionized water at 70 to 80°C, and the pH is adjusted to 2 to 4 to obtain a soap solution. 50 to 60 parts of asphalt are heated to 120 to 130°C, and then mixed with the soap solution and added to a colloid mill for grinding for 6 to 8 minutes to obtain carboxylated cationic emulsified asphalt.

4. The method for preparing asphalt concrete at room temperature according to claim 1, characterized in that, The fiber material is an activated fiber composite material; The preparation method of the activated fiber composite material includes: activating alumina fibers with calcium hydroxide suspension to obtain the activated fiber composite material.

5. The method for preparing asphalt concrete at room temperature according to claim 4, characterized in that, The activation treatment steps are as follows: immerse alumina fibers in a 1 mol / L calcium hydroxide suspension for 4-6 hours, then dry them at 100-110℃ for 50-60 minutes, and finally activate them at 200-240℃ for 120-160 minutes to obtain activated fiber composite materials.

6. The method for preparing asphalt concrete at room temperature according to claim 5, characterized in that, The alumina fiber is Dongheng Guoxian's 72-F alumina fiber, with a chemical composition of alumina to silicon dioxide mass ratio of 72:28 and a density of 3.1 g / cm³. 3 The average fiber diameter is 5.5-7.5μm, and the impurity content is <0.5%.

7. The method for preparing asphalt concrete at room temperature according to claim 1, characterized in that, The aggregate is limestone crushed stone and steel slag; The mass ratio of the limestone crushed stone to the steel slag is (1~2):

1.

8. The method for preparing asphalt concrete at room temperature according to claim 7, characterized in that, The limestone crushed stone has a particle size of 5-10 mm, an abrasion loss of 11-12%, and an apparent relative density of 2.7-2.8 g / cm³. 3 The water absorption rate is 0.5~0.6%.

9. The method for preparing asphalt concrete at room temperature according to claim 7, characterized in that, The steel slag has a particle size of 9-16 mm and an apparent relative density of 3.5-3.7 g / cm³. 3 The content of needle-like and flaky particles (>9.5mm) is 4.8~5.0%, the crushing value is 13~14%, and the abrasion loss is 16~18%.

10. The method for preparing asphalt concrete at room temperature according to claim 1, characterized in that, The apparent density of the limestone powder is 2.6~2.7 g / cm³. 3 The hydrophilicity coefficient is 0.8~0.9, with 100% for particle size less than 0.6mm, 92~94% for particle size less than 0.15mm, and 80~82% for particle size less than 0.075mm.

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