A cold-mix asphalt mixture and a method for preparing the same

Abstract

The present application belongs to the technical field of asphalt pavement material and preparation, and particularly relates to a cold-mixed asphalt mixture and a preparation method thereof. The cold-mixed asphalt mixture comprises aggregate 92-94 parts, cationic modified emulsified asphalt 6.0-8.0 parts, mineral powder 6-8 parts, and mixing water 2-4 parts. The cationic modified emulsified asphalt comprises modified asphalt 60-65 parts and composite water phase 35-40 parts. The preparation method of the cold-mixed asphalt mixture comprises the following steps: firstly, uniformly stirring the aggregate prepared according to the particle size gradation and the mineral powder, and then wet mixing; and then adding the cationic modified emulsified asphalt and continuously stirring to obtain the cold-mixed asphalt mixture. Under the synergistic effect of the aggregate and the cationic modified emulsified asphalt, the cold-mixed asphalt mixture has excellent Marshall stability, excellent high-temperature anti-rutting performance and low-temperature anti-cracking performance, and the durability is also greatly improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of asphalt pavement materials and preparation, and particularly relates to a cold-mixed asphalt mixture and a preparation method thereof. BACKGROUND

[0002] The main raw materials of the cold-mixed asphalt mixture are aggregate and asphalt. Such asphalt mixture is mixed at room temperature without heating the aggregate and asphalt. The cold-mixed asphalt mixture has rapidly developed due to its convenient construction, small environmental pollution, and low carbon emission. At present, the cold-mixed asphalt mixture has shown good application prospects in road surface layers.

[0003] However, the existing cold-mixed asphalt mixture still has many technical defects, which are difficult to completely meet the actual construction requirements. Among them, the more prominent problems are:

[0004] 1. The emulsified asphalt, which is the core component of the cold-mixed asphalt mixture, has poor storage stability, which leads to core defects such as segregation of the asphalt mixture, insufficient adhesion, insufficient strength and durability, etc. In addition, the flowability of the layered emulsified asphalt is unstable, and the distribution of coarse and fine aggregates in the mixed mixture is uneven. During paving, it is easy to move, clump, and increase the difficulty of compaction, which affects the flatness of the pavement and deteriorates the workability of the construction.

[0005] 2. The breaking time is difficult to control, and the breaking speed of the emulsified asphalt is often significantly affected by the environment, which makes it difficult to form strength in time, leading to insufficient overall strength of the asphalt mixture, decreased crack resistance and water damage resistance, and shortened service life of the pavement. The construction quality fluctuates greatly, making it difficult to ensure the stability and consistency of the engineering quality.

[0006] 3. The water quality requirement is high. In hard water conditions, impurities in water can damage the interfacial adhesion between asphalt and aggregate. High-hardness water (containing too much calcium and magnesium ions) may cause abnormal condensation of the mixture, decrease the stability, and easily interfere with the emulsion system by calcium and magnesium ions, thereby affecting the construction of the mixture.

[0007] Patent CN119191763A discloses a preparation method of emulsified asphalt mixture. The method uses SBS, petroleum resin and rubber powder to modify the asphalt, and then adds cationic emulsifier, stabilizer, early strength agent and other raw materials to prepare modified emulsified asphalt. The emulsified asphalt mixture prepared by the present application has excellent mechanical properties, but the early strength agent used in the present application is an inorganic material, and the breaking time of the emulsified asphalt is extremely sensitive to the amount of early strength agent, which greatly affects the road performance of the emulsified asphalt mixture.

[0008] Patent CN108129073A discloses a kind of cold mixing and cold paving asphalt mixture and cold mixing and cold paving asphalt mixture wearing layer, the asphalt mixture in the patent includes the following components: coarse aggregate 50~80 parts, fine aggregate 20~50 parts, modified emulsified asphalt 10~16 parts, mineral filler 0~3 parts, water 0~12 parts, liquid additive 0~5 parts.The modified emulsified asphalt is star-shaped SBS modified asphalt or linear SBS modified asphalt, the mass content of SBS modifier in the modified emulsified asphalt is not less than 4%.By the matching ratio design of coarse and fine aggregate, combined with high proportion of modified emulsified asphalt addition, improve the adhesion effect of mixture and old pavement, the crack resistance of mixture itself and the water sealing effect;In addition, the determination of high emulsified asphalt addition and suitable mineral aggregate gradation range can reduce the driving noise of pavement.But the modified emulsified asphalt used in the invention is single SBS modified emulsified asphalt, which may occur polymer and base asphalt phase separation phenomenon during long time storage, and the low temperature crack resistance of single SBS modified emulsified asphalt is poor.

[0009] In summary, although the cold mixing asphalt mixture has good application prospect, there are still problems such as mixture segregation, workability, strength and durability, which restrict the adaptability and reliability of cold mixing mixture in different environments to some extent, so it is urgent to improve. SUMMARY

[0010] The purpose of the present application is to provide a kind of cold mixing asphalt mixture and its preparation method for the above-mentioned defects.The cold mixing asphalt mixture has excellent Marshall stability and excellent high temperature anti-rutting and low temperature crack resistance under the synergistic effect of the aggregate and cationic modified emulsified asphalt, and its durability has also been greatly improved.

[0011] The specific technical solutions are as follows:

[0012] A kind of cold mixing asphalt mixture, which includes the following raw materials by weight: aggregate 92-94 parts, cationic modified emulsified asphalt 6.0-8.0 parts, mineral powder 6-8 parts, mixing water 2-4 parts.

[0013] The particle size gradation of the aggregate is: particle size 13.2-9.5mm is 10-14 parts, particle size 9.5-4.75mm is 26-30 parts, particle size 4.75-2.36mm is 20-24 parts, particle size 2.36-0.6mm is 16-20 parts, particle size 0.6-0.075mm is 10-14 parts.

[0014] The particle size of the mineral powder is <0.075mm.

[0015] The cationic modified emulsified asphalt is composed of the following raw materials by weight: modified asphalt 60-65 parts, composite water phase 35-40 parts.

[0016] The modified asphalt is composed of the following raw materials in parts by weight: 85-90 parts of base asphalt, 2-5 parts of linear SBS modifier, 7-10 parts of rubber powder, and 1-1.5 parts of industrial sulfur powder; the polystyrene block in the linear SBS modifier accounts for 29-31%. The linear SBS modifier is a linear block copolymer of styrene (PS)-butadiene (PB)-styrene (PS); the sum of the proportion of the polystyrene (PS) block and the proportion of the polybutadiene (PB) block is 100%. That is, the block ratio of the linear SBS modifier is PS:PB=(29-31):(71-69). The linear SBS modifier with the block ratio is used in the cold-mixed asphalt mixture system, which can not only balance the high-temperature rutting resistance and low-temperature cracking resistance of the asphalt mixture, but also reduce the amount of SBS modifier, thereby reducing the cost of the asphalt mixture.

[0017] The composite water phase is compounded from the following raw materials in parts by weight: 90-95 parts of water, 1.5-3.0 parts of hydroxyethyl cetyl dimethyl ammonium chloride, 0.1-0.6 parts of alkylphenol polyoxyethylene ether, 0.6-1.2 parts of glacial acetic acid, 0.06-0.24 parts of sodium tripolyphosphate, and 0.2-0.7 parts of hydroxypropyl methyl cellulose; the alkylphenol polyoxyethylene ether has 9-10 carbon atoms and a polymerization degree of 8-10.

[0018] The hydroxyethyl cetyl dimethyl ammonium chloride is obtained by reacting cetyl dimethyl amine with ethylene oxide and further quaternary amination.

[0019] In the cold-mixed asphalt mixture system, the modified asphalt is emulsified by the composite water phase, and a stable elastic network three-dimensional skeleton can be formed in the cold-mixed asphalt mixture system, which provides stress buffering for the system, inhibits the initiation and development of cracks, and further improves the anti-peeling capacity between the cationic modified emulsified asphalt film and the aggregate interface, and enhances the mechanical properties of the mixture. In addition, the network structure can limit the migration of asphaltene and light components, which helps to alleviate the performance degradation of the mixture caused by thermal oxidative aging, and further improves the road performance of the cold-mixed mixture. Furthermore, the rubber powder and industrial sulfur powder further reduce the cost of the asphalt mixture.

[0020] In the present application, when the weight ratio of hydroxyethyl cetyl dimethyl ammonium chloride to alkylphenol polyoxyethylene ether in the composite water phase of the cold-mixed asphalt mixture is (5-6):1, the demulsification time of the cationic modified emulsified asphalt in the cold-mixed asphalt mixture is 12-20 min.

[0021] When the weight ratio of hydroxyethyl hexadecyl dimethyl ammonium chloride to alkylphenol polyoxyethylene ether in the composite aqueous phase is (6.5-11.5):1, the demulsification time of cationic modified emulsified asphalt in cold-mix asphalt mixture is 6-11 min.

[0022] When the weight ratio of hydroxyethyl hexadecyl dimethyl ammonium chloride to alkylphenol polyoxyethylene ether in the composite aqueous phase is (12.5-20):1, the demulsification time of cationic modified emulsified asphalt in cold-mix asphalt mixture is 3-5 min.

[0023] When the weight ratio of hydroxyethyl hexadecyl dimethyl ammonium chloride to alkylphenol polyoxyethylene ether in the composite aqueous phase is (21-30):1, the demulsification time of cationic modified emulsified asphalt in cold-mix asphalt mixture is 1-2 min.

[0024] The cold-mix asphalt mixture of the present invention can control the demulsification time by the compounding ratio between the composite aqueous raw material hydroxyethyl hexadecyl dimethyl ammonium chloride and alkylphenol polyoxyethylene ether in the system, so as to obtain cold-mix asphalt mixtures that can meet different needs, such as slow-breaking, medium-breaking, fast-breaking and ultra-fast-breaking.

[0025] In this invention, the base asphalt in the modified asphalt of the cationic modified emulsified asphalt raw material of the cold-mix asphalt mixture is No. 90 road petroleum asphalt.

[0026] In this invention, the cold-mix asphalt mixture uses cationic modified emulsified asphalt as the raw material for the modified asphalt, which is waste tire rubber powder with a particle size of 40 mesh; the rubber hydrocarbon content in the rubber powder is 55%-60%; the carbon black content is 30%-35%; and the ash content is 5%-8%.

[0027] In this invention, the water in the composite aqueous phase of the cold-mix asphalt mixture is selected from tap water or mixing water. The cold-mix asphalt mixture system has high stability, is largely unaffected by calcium and magnesium ions in high-hardness water, and has low requirements for water quality.

[0028] In this invention, the cold-mix asphalt mixture is prepared by the following steps:

[0029] (1) Preparation of modified asphalt:

[0030] The base asphalt is heated to 160°C-170°C and kept in a fluid state before being transferred to an oil bath. Linear SBS modifier is added to the oil bath and stirred until homogeneous to obtain a mixture.

[0031] First, the mixture is sheared at a shear rate of 2000-3000 rpm for 60-90 minutes until the SBS is completely swollen;

[0032] Then, the shearing rate is reduced to 150-200 rpm, the rubber powder is added, and sheared for 5-10 min; then the shearing rate is increased to 3000-4000 rpm, and sheared for 30-45 min before adding industrial sulfur powder;

[0033] Finally, the shearing rate is reduced to 150-200 rpm, and sheared for 30-40 min to obtain the modified asphalt, which is kept at 160-170℃ and ready for use.

[0034] (2) Preparation of composite aqueous phase:

[0035] First, heat the water to 65-80℃, then add sodium tripolyphosphate, and stir until the sodium tripolyphosphate is completely dissolved;

[0036] Then, add hydroxyethylhexadecyl dimethyl ammonium chloride, and continue to stir until completely dissolved;

[0037] Add glacial acetic acid dropwise, and adjust the pH of the solution to 2.0-3.0;

[0038] Add hydroxypropyl methyl cellulose, stir for 20-30 min, then add alkylphenol polyoxyethylene ether, and continue to stir for 5-10 min; to prepare the composite aqueous phase.

[0039] (3) Preparation of cationic modified emulsified asphalt:

[0040] First, the obtained composite aqueous phase is put into a colloid mill for circulation treatment, wherein the colloid mill rotation speed is 1000-1500 rpm, and the circulation time is 3-5 min;

[0041] Then, the colloid mill rotation speed is increased to 3000-5000 rpm, and the inlet pressure is ensured to be 0.10-0.20 MPa; the obtained modified asphalt is put into the colloid mill for mixing, and the outlet temperature is controlled at 90-95℃; the luster and uniformity of the discharged material are observed, and there is no strip / oil;

[0042] Finally, the material is discharged, and the discharged material is cooled to below 65℃, and aged for 12-24 h, then sieved through a 100 mesh sieve, and then loaded into a container to obtain the cationic modified emulsified asphalt.

[0043] Further, the stirring speed of the linear SBS modifier and the base asphalt in step (1) of preparing the cationic modified emulsified asphalt in the cold-mixed asphalt mixture is 200-300 rpm, and the stirring time is 20-30 min.

[0044] In the application, the cationic modified emulsified asphalt of the cold-mixed asphalt mixture has a difference of residual content between upper and lower layers of ≤0.7% after storage for 1 day, and a difference of residual content between upper and lower layers of ≤1.5% after storage for 5 days; and the Saybolt viscosity of the cationic modified emulsified asphalt is 87-216 s. No coarse particles and no caking phenomenon occur under the freeze-thaw condition of-5 ℃.

[0045] In the application, the Marshall stability of the cold-mixed asphalt mixture is 10-10.7 kN, the dynamic stability is 8700-9200 times / mm, and the freeze-thaw splitting strength ratio is 94-97.6%.

[0046] The preparation method of the cold-mixed asphalt mixture comprises the following steps:

[0047] First, the aggregate prepared according to the particle size gradation and the mineral powder are put into a mixer, and stirred at a stirring speed of 60-120 rpm for 15-30 s.

[0048] After uniform stirring, a part of the mixing water is added for wet mixing, and the wet mixing time is 15-30 s; wherein the addition amount of the part of the mixing water accounts for 70%-80% of the total weight of the mixing water.

[0049] Then, the cationic modified emulsified asphalt is added within 15-30 s, and the remaining mixing water is added for continuous stirring for 60-90 s, to obtain the cold-mixed asphalt mixture.

[0050] The cold-mixed asphalt mixture system of the application has the following beneficial effects: the cationic modified emulsified asphalt used in the cold-mixed asphalt mixture system can form a dense bonding film in the aggregate, so that the cold-mixed asphalt mixture has excellent Marshall stability, excellent high-temperature anti-rutting and low-temperature anti-cracking performance, and the durability is also greatly improved.

[0051] The cold-mixed asphalt mixture has enhanced construction adaptability, the breaking time of the modified emulsified asphalt can be accurately controlled through formula design, covering slow breaking, medium breaking, fast breaking, and super-fast breaking, to meet the needs of different construction scenes. Moreover, the asphalt mixture system has strong adaptability to water quality and environment, and can be directly mixed with ordinary water, which significantly improves the environmental adaptability and construction reliability. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 The Marshall stability and freeze-thaw splitting strength ratio test piece in the specific embodiment.

[0053] Figure 2 The dynamic stability and rut depth test piece in the specific embodiment. DETAILED DESCRIPTION

[0054] The technical solutions of the present application are described in detail below.

[0055] 1. The test methods of Marshall stability, freeze-thaw splitting strength, dynamic stability, rut depth, and 1d and 5d storage stability are all performed in accordance with the “Standard Test Methods for Asphalt and Asphalt Mixtures” (JTG E20-2011).

[0056] 2. The test method of Saybolt viscosity: 60 mL of sample is filtered and injected into a Saybolt viscometer, the hole is blocked, and the temperature is kept constant to the specified temperature (25℃) for equilibrium; the plug is pulled out and the flow is measured, and the time for a specified volume to flow out is recorded in seconds; after testing, the constant temperature is cleaned and calibrated.

[0057] 3. The test method of demulsification time: clean standard sand is evenly spread into a sand layer with a thickness of 2.5±0.5 mm, lightly vibrated and settled for 1 min. 1.0±0.2 g of emulsified asphalt sample is added to the center of the sand surface, and the stopwatch is started immediately. When a continuous black film forms on the sand surface, use tweezers or other tools to lightly touch the film, and record the time when the film can be removed as a whole and does not stick to the hand when touched. This time can be used as the demulsification time.

[0058] Example 1

[0059] The cold-mixed asphalt mixture comprises the following raw materials by weight: aggregate 94 parts, cationic modified emulsified asphalt 6.0 parts, mineral powder 6 parts, and mixing water 2 parts.

[0060] The particle size gradation of the aggregate is: 12 parts of particle size 13.2-9.5 mm, 26 parts of particle size 9.5-4.75 mm, 20 parts of particle size 4.75-2.36 mm, 16 parts of particle size 2.36-0.6 mm, and 12 parts of particle size 0.6-0.075 mm.

[0061] The particle size of the mineral powder is <0.075 mm.

[0062] The cationic modified emulsified asphalt is composed of the following raw materials by weight: modified asphalt 62 parts and composite water phase 38 parts.

[0063] The modified asphalt is composed of the following raw materials by weight: 90# road petroleum asphalt 87 parts, linear SBS modifier 3 parts, rubber powder 10 parts, and industrial sulfur powder 1 part.

[0064] The proportion of polystyrene blocks in the linear SBS modifier is 31%, and the proportion of polybutadiene blocks is 69%.

[0065] The rubber powder is 40-mesh waste tire rubber powder, the rubber hydrocarbon content in the rubber powder is 60%, the carbon black content is 30%, and the ash content is 8%.

[0066] The composite water phase is compounded from the following raw materials by weight: 95 parts of water for mixing, 1.5 parts of hydroxyethyl cetyl dimethyl ammonium chloride, 0.3 parts of alkyl phenol polyoxyethylene ether, 0.6 parts of glacial acetic acid, 0.24 parts of sodium tripolyphosphate, and 0.6 parts of hydroxypropyl methyl cellulose.

[0067] The alkyl phenol polyoxyethylene ether has 9 carbon atoms and a polymerization degree of 10.

[0068] The cationic modified emulsified asphalt in the cold-mixed asphalt mixture is prepared by the following steps:

[0069] (1) Preparation of modified asphalt:

[0070] After the base asphalt is heated to 170°C, it is transferred to an oil bath pot, and linear SBS modifier is added to the oil bath pot, and stirred at a stirring speed of 300 rpm for 30 min to obtain a mixture;

[0071] First, the mixture is sheared at a shearing speed of 3000 rpm for 60 min;

[0072] Then, the shearing speed is reduced to 200 rpm, the rubber powder is added, and sheared for 10 min; then the shearing speed is increased to 3000 rpm, and the industrial sulfur powder is added after continuing to shear for 30 min;

[0073] Finally, the shearing speed is reduced to 200 rpm, and sheared for 40 min to obtain the modified asphalt, which is kept at 170°C for standby.

[0074] (2) Preparation of composite water phase:

[0075] First, heat the water to 70°C, then add sodium tripolyphosphate, and stir until the sodium tripolyphosphate is completely dissolved;

[0076] Then, add hydroxyethyl cetyl dimethyl ammonium chloride, and continue to stir until completely dissolved;

[0077] Add glacial acetic acid dropwise, and adjust the pH of the solution to 2.0;

[0078] Add hydroxypropyl methyl cellulose, stir for 30 min, and then add alkyl phenol polyoxyethylene ether, and continue to stir for 10 min; to obtain the composite water phase.

[0079] (3) Preparation of cationic modified emulsified asphalt:

[0080] First, the obtained composite water phase is added to a colloid mill for circulation treatment, wherein the rotation speed of the colloid mill is 1500 rpm, and the circulation time is 5 min;

[0081] Then, the colloid mill speed is increased to 5000 rpm, and the inlet pressure is ensured to be 0.10 MPa; the obtained modified asphalt is put into the colloid mill for mixing, and the outlet temperature is controlled to be 95℃; the discharge luster and uniformity are observed, and there is no strip / oil.

[0082] Finally, the discharge is cooled to below 65℃, and is left to stand for 24h for curing; after being sieved through a 100-mesh sieve, the discharge is loaded into a container, and the cationic modified emulsified asphalt is obtained.

[0083] The preparation method of the cold-mixed asphalt mixture comprises the following specific steps:

[0084] Firstly, the aggregate prepared according to the particle size gradation and the mineral powder are put into a mixer, and are stirred at a stirring speed of 120 rpm for 15s;

[0085] After being stirred uniformly, a part of the mixing water is added for wet mixing, and the wet mixing time is 30s; wherein, the adding amount of the part of the mixing water accounts for 70% of the total weight of the mixing water;

[0086] Then, the cationic modified emulsified asphalt is added within 30s; the remaining mixing water is further added for stirring for 90s, until the color of the mixture is uniform and there is no lump, and the cold-mixed asphalt mixture is obtained.

[0087] Example 2

[0088] The cold-mixed asphalt mixture comprises the following raw materials in parts by weight: aggregate 93 parts, cationic modified emulsified asphalt 7 parts, mineral powder 7 parts, and mixing water 3 parts.

[0089] The particle size gradation of the aggregate is as follows: particle size 13.2-9.5mm is 12 parts, particle size 9.5-4.75mm is 30 parts, particle size 4.75-2.36mm is 22 parts, particle size 2.36-0.6mm is 17 parts, and particle size 0.6-0.075mm is 12 parts.

[0090] The particle size of the mineral powder is less than 0.075mm.

[0091] The cationic modified emulsified asphalt is composed of the following raw materials in parts by weight: modified asphalt 63 parts and composite water phase 37 parts.

[0092] The modified asphalt is composed of the following raw materials in parts by weight: 90# road petroleum asphalt 88 parts, linear SBS modifier 2 parts, rubber powder 8 parts, and industrial sulfur powder 1.5 parts.

[0093] The proportion of polystyrene block in the linear SBS modifier is 29%, and the proportion of polybutadiene block is 71%.

[0094] The rubber powder is 40-mesh waste tire rubber powder; the rubber hydrocarbon content in the rubber powder is 55%; the carbon black content is 35%; and the ash content is 5%.

[0095] The composite water phase is compounded from the following raw materials by weight: 93 parts of mixing water, 2.0 parts of hydroxyethylhexadecyl dimethyl ammonium chloride; 0.3 parts of alkylphenol polyoxyethylene ether; 0.8 parts of glacial acetic acid; 0.18 parts of sodium tripolyphosphate; 0.7 parts of hydroxypropyl methyl cellulose; the alkylphenol polyoxyethylene ether has 10 carbon atoms and a polymerization degree of 8.

[0096] Example 3

[0097] The cold-mixed asphalt mixture comprises the following raw materials by weight: 92 parts of aggregate, 8.0 parts of cationic modified emulsified asphalt, 8 parts of mineral powder, and 4 parts of mixing water.

[0098] The particle size grading of the aggregate is as follows: 10 parts of particle size 13.2-9.5 mm, 27 parts of particle size 9.5-4.75 mm, 23 parts of particle size 4.75-2.36 mm, 20 parts of particle size 2.36-0.6 mm, and 14 parts of particle size 0.6-0.075 mm.

[0099] The particle size of the mineral powder is less than 0.075 mm.

[0100] The cationic modified emulsified asphalt is composed of the following raw materials by weight: 64 parts of modified asphalt and 36 parts of composite water phase.

[0101] The modified asphalt is composed of the following raw materials by weight: 86 parts of No. 90 road petroleum asphalt, 4 parts of linear SBS modifier, 7 parts of rubber powder, and 1.5 parts of industrial sulfur powder.

[0102] The proportion of polystyrene blocks in the linear SBS modifier is 31%, and the proportion of polybutadiene blocks is 69%.

[0103] The rubber powder is 40-mesh waste tire rubber powder; the rubber hydrocarbon content in the rubber powder is 60%; the carbon black content is 30%; and the ash content is 8%.

[0104] The composite water phase is compounded from the following raw materials by weight: 92 parts of mixing water, 2.5 parts of hydroxyethylhexadecyl dimethyl ammonium chloride; 0.2 parts of alkylphenol polyoxyethylene ether; 1.0 parts of glacial acetic acid; 0.15 parts of sodium tripolyphosphate; 0.6 parts of hydroxypropyl methyl cellulose; the alkylphenol polyoxyethylene ether has 9 carbon atoms and a polymerization degree of 10.

[0105] Example 4

[0106] The cold-mixed asphalt mixture comprises the following raw materials by weight: aggregate 93 parts, cationic modified emulsified asphalt 7.0 parts, mineral powder 7 parts, and mixing water 4 parts.

[0107] The particle size grading of the aggregate is: 10 parts of 13.2-9.5 mm, 26 parts of 9.5-4.75 mm, 23 parts of 4.75-2.36 mm, 19 parts of 2.36-0.6 mm, and 14 parts of 0.6-0.075 mm.

[0108] The particle size of the mineral powder is <0.075 mm.

[0109] The cationic modified emulsified asphalt is composed of the following raw materials by weight: modified asphalt 65 parts and composite water phase 35 parts.

[0110] The modified asphalt is composed of the following raw materials by weight: 90# road petroleum asphalt 85 parts, linear SBS modifier 5 parts, rubber powder 10 parts, and industrial sulfur powder 1 part.

[0111] The proportion of polystyrene block in the linear SBS modifier is 30%, and the proportion of polybutadiene block is 70%.

[0112] The rubber powder is 40-mesh waste tire rubber powder, the rubber hydrocarbon content in the rubber powder is 60%, the carbon black content is 30%, and the ash content is 8%.

[0113] The composite water phase is compounded from the following raw materials by weight: mixing water 90 parts, hydroxyethylhexadecyl dimethyl ammonium chloride 3.0 parts, alkyl phenol polyoxyethylene ether 0.1 part, glacial acetic acid 1.2 parts, sodium tripolyphosphate 0.2 part, and hydroxypropyl methyl cellulose 0.5 part; the alkyl phenol polyoxyethylene ether has 9 carbon atoms and a polymerization degree of 10.

[0114] Comparative Example 1

[0115] The cold-mixed asphalt mixture of the present comparative example is different from Example 1 in that the aggregate is 90 parts, the cationic modified emulsified asphalt is 10 parts, the mineral powder is 10 parts, and the mixing water is 6 parts.

[0116] The other parts are the same as in Example 1.

[0117] Comparative Example 2

[0118] The cold-mixed asphalt mixture of the present comparative example is different from Example 1 in that the particle size grading of the aggregate is: 20 parts of 13.2-9.5 mm, 20 parts of 9.5-4.75 mm, 25 parts of 4.75-2.36 mm, 15 parts of 2.36-0.6 mm, and 5 parts of 0.6-0.075 mm.

[0119] 15 parts of mineral powder with a particle size <0.075mm.

[0120] The others are the same as in Example 1.

[0121] Comparative Example 3

[0122] The difference between the cold-mix asphalt mixture described in this comparative example and Example 1 is that the base asphalt of the modified asphalt is No. 70 road petroleum asphalt.

[0123] The others are the same as in Example 1.

[0124] Comparative Example 4

[0125] The cold-mix asphalt mixture described in this comparative example differs from that in Example 1 in that the polystyrene block content in the linear SBS modifier of the modified asphalt is 40%, and the polybutadiene block content is 60%.

[0126] The others are the same as in Example 1.

[0127] Comparative Example 5

[0128] The cold-mix asphalt mixture described in this comparative example differs from that in Example 1 in that the raw material hydroxyethylhexadecyl dimethyl ammonium chloride in the composite aqueous phase is replaced with hexadecyl trimethyl ammonium chloride.

[0129] The others are the same as in Example 1.

[0130] Comparative Example 6

[0131] The cold-mixed asphalt mixture described in this comparative example differs from that in Example 1 in that the composite aqueous phase uses alkylphenol polyoxyethylene ether with 12 carbon atoms and a degree of polymerization of 12.

[0132] The others are the same as in Example 1.

[0133] Comparative Example 7

[0134] The cold-mixed asphalt mixture described in this comparative example differs from that in Example 1 in that the raw material hydroxypropyl methylcellulose in the composite aqueous phase is replaced with hydroxyethyl cellulose.

[0135] The others are the same as in Example 1.

[0136] Comparative Example 8

[0137] The cold-mix asphalt mixture described in this comparative example differs from that in Example 1 in that the modified asphalt is composed of the following raw materials in parts by weight: 80 parts of base asphalt, 7 parts of linear SBS modifier, 12 parts of rubber powder, and 3.0 parts of industrial sulfur powder.

[0138] The others are the same as in Example 1.

[0139] Comparative Example 9

[0140] The cold-mixed asphalt mixture of the present comparative example is different from Example 1 in that the composite water phase is compounded from the following raw materials by weight: mixing water 90 parts, hydroxyethyl hexadecyl dimethyl ammonium chloride 5.0 parts; alkyl phenol polyoxyethylene ether 1.0 part; glacial acetic acid 1.5 parts; sodium tripolyphosphate 0.5 part, hydroxypropyl methyl cellulose 1.5 parts.

[0141] The rest is the same as Example 1.

[0142] Comparative Example 10

[0143] The cold-mixed asphalt mixture of the present comparative example is different from Example 1 in that the cationic modified emulsified asphalt is composed of the following raw materials by weight: modified asphalt 70 parts, composite water phase 30 parts.

[0144] The rest is the same as Example 1.

[0145] Comparative Example 11

[0146] The cold-mixed asphalt mixture of the present comparative example is different from Example 1 in that the cationic modified emulsified asphalt is composed of the following raw materials by weight: modified asphalt 50 parts, composite water phase 50 parts.

[0147] The rest is the same as Example 1.

[0148] Table 1 Performance indicators of the cold-mixed asphalt mixture of each example and comparative example

[0149]

[0150] Table 2 Performance indicators of each cationic modified emulsified asphalt in Examples 1-4 and Comparative Examples 3-11

[0151]

[0152] According to the data in Table 1, the Marshall stability of Examples 1-4 is 10.0-10.7 kN, the dynamic stability is 8700-9200 times / mm, the rut depth is 1.2-1.5 mm, and the freeze-thaw splitting strength ratio is 94.0%-97.6%.

[0153] Comparative Example 1 has deteriorated in all indicators compared with Examples 1-4, indicating that the ratio composition of the present application is reasonable.

[0154] Comparative Example 2 has increased Marshall stability and improved rut resistance compared with Examples 1-4, but has decreased low-temperature crack resistance, indicating that the particle size grading of the aggregate in the present application can balance the high and low temperature performance of the mixture.

[0155] Compared with Examples 1-4, the raw material composition of the cationic emulsified asphalt in Comparative Examples 3-7 is changed, which results in that the Marshall stability, high-temperature performance and low-temperature performance of the mixture cannot be balanced, indicating that the selection of various raw materials in the present application is very reasonable.

[0156] Compared with Examples 1-4, the raw material proportion in the modified asphalt and the composite water phase is changed in Comparative Examples 8-9. The Marshall stability and high-temperature performance of Comparative Example 8 are improved, but the low-temperature performance is greatly decreased. The performance of Comparative Example 9 is all deteriorated. It is indicated that the proportion of each material in the modified asphalt and the composite water phase in the present application can simultaneously consider the strength and high-temperature performance and low-temperature performance.

[0157] Compared with Examples 1-4, the proportion between the modified asphalt and the composite water phase is changed in Comparative Examples 10-11, and the performance of the mixture is all deteriorated, indicating that the proportion between the modified asphalt and the composite water phase in the present application is reasonable.

[0158] It can be known from the data in Table 2 that the cationic modified emulsified asphalt in Examples 1-4 has good construction and easy performance and is easy to pump. The 1d storage stability is greater than 99.3% (100%-residual content difference between upper and lower layers), and the 5d storage stability is greater than 98.5%, which is higher than the storage stability of conventional emulsified asphalt.

[0159] According to different application requirements, the demulsification time of the cationic modified emulsified asphalt in Examples 1-4 can be divided into four types: slow demulsification (12-20min), medium demulsification (6-11min), fast demulsification (3-5min) and super-fast demulsification (1-2min).

[0160] Compared with Examples 1-4, the type of the base asphalt of the cationic modified emulsified asphalt in Comparative Example 3 is changed from No. 90 to No. 70, and the Saybolt viscosity of the cationic modified emulsified asphalt is greatly increased, indicating that the construction and easy performance is deteriorated.

[0161] In addition, the 1d and 5d storage stability of Comparative Example 1 is also greatly decreased, indicating that No. 90 asphalt is more suitable for the present application.

[0162] Compared with Examples 1-4, the block ratio of the SBS modifier of the cationic modified emulsified asphalt in Comparative Example 4 is changed from 30:70 to 40:60. After the change, the storage stability of the cationic modified emulsified asphalt is decreased. It is indicated that the selection of the block ratio of the SBS modifier used in the present application is reasonable.

[0163] Compared with Examples 1-4, the cationic emulsifier of the modified emulsified asphalt in Comparative Example 5 is changed to hexadecyl trimethyl ammonium chloride, the storage stability of the modified emulsified asphalt is decreased, and the demulsification time is increased. It is indicated that the cationic emulsifier in the present application is reasonable.

[0164] Comparative Example 6 compared with Examples 1-4, the carbon chain number and the polymerization degree of the alkyl phenol polyoxyethylene ether were changed, the Saybolt viscosity of the cationic modified emulsified asphalt increased greatly, the 1d and 5d storage stability greatly decreased, and the demulsification time became uncontrollable. It is illustrated that the carbon chain number and the polymerization degree of the alkyl phenol polyoxyethylene ether used in the present application are in a reasonable range, which can ensure that the asphalt micro-droplets are not too hydrophilic, and also can ensure that they are not too hydrophobic to cause phase separation.

[0165] Comparative Example 7 compared with Examples 1-4, the type of stabilizer was changed to hydroxyethyl cellulose, the Saybolt viscosity increased, the workability became poor, the 1d and 5d storage stability decreased, and the demulsification time was difficult to control. It is illustrated that the type of stabilizer selected in the present application is reasonable.

[0166] Comparative Example 8 compared with Examples 1-4, the content of each component in the modified asphalt changed. The Saybolt viscosity of the cationic modified emulsified asphalt increased, the workability decreased, the storage stability greatly decreased, and the demulsification time increased. It is illustrated that the proportion of each component in the modified asphalt in the present application is reasonable.

[0167] Comparative Example 9 compared with Examples 1-4, the proportion of each component in the aqueous phase was changed, the demulsification time of the cationic modified emulsified asphalt was ≤1min, and was very difficult to control. It is illustrated that the proportion of each component in the aqueous phase in the present application is reasonable.

[0168] Comparative Examples 10-11 compared with Examples 1-4, the proportion between the modified asphalt and the composite aqueous phase was changed, the workability and the storage stability of the cationic modified emulsified asphalt decreased, and the demulsification time was difficult to control.

Claims

1. A cold-mix asphalt mixture, characterized in that, The raw materials include the following parts by weight: 92-94 parts aggregate, 6.0-8.0 parts cationic modified emulsified asphalt, 6-8 parts mineral powder, and 2-4 parts mixing water; The aggregate has the following particle size distribution: 10-14 parts for particles with a diameter of 13.2-9.5 mm, 26-30 parts for particles with a diameter of 9.5-4.75 mm, 20-24 parts for particles with a diameter of 4.75-2.36 mm, 16-20 parts for particles with a diameter of 2.36-0.6 mm, and 10-14 parts for particles with a diameter of 0.6-0.075 mm. The particle size of the mineral powder is <0.075 mm; The cationic modified emulsified asphalt is composed of the following raw materials in parts by weight: 60-65 parts modified asphalt and 35-40 parts composite aqueous phase. The modified asphalt is composed of the following raw materials in parts by weight: 85-90 parts of base asphalt, 2-5 parts of linear SBS modifier, 7-10 parts of rubber powder, and 1-1.5 parts of industrial sulfur powder; the polystyrene block content in the linear SBS modifier is 29-31%; and the base asphalt is No. 90 road petroleum asphalt. The composite aqueous phase is composed of the following raw materials in parts by weight: 90-95 parts water, 1.5-3.0 parts hydroxyethyl hexadecyl dimethyl ammonium chloride, 0.1-0.6 parts alkylphenol polyoxyethylene ether, 0.6-1.2 parts glacial acetic acid, 0.06-0.24 parts sodium tripolyphosphate, and 0.2-0.7 parts hydroxypropyl methylcellulose; wherein the alkylphenol polyoxyethylene ether has 9-10 carbon atoms and a degree of polymerization of 8-10. Wherein, when the weight ratio of hydroxyethyl hexadecyl dimethyl ammonium chloride to alkylphenol polyoxyethylene ether in the composite aqueous phase is (5-6):1, the demulsification time of cationic modified emulsified asphalt in cold-mix asphalt mixture is 12-20 min. When the weight ratio of hydroxyethyl hexadecyl dimethyl ammonium chloride to alkylphenol polyoxyethylene ether in the composite aqueous phase is (6.5-11.5):1, the demulsification time of cationic modified emulsified asphalt in cold-mix asphalt mixture is 6-11 min. When the weight ratio of hydroxyethyl hexadecyl dimethyl ammonium chloride to alkylphenol polyoxyethylene ether in the composite aqueous phase is (12.5-20):1, the demulsification time of cationic modified emulsified asphalt in cold-mix asphalt mixture is 3-5 min. When the weight ratio of hydroxyethyl hexadecyl dimethyl ammonium chloride to alkylphenol polyoxyethylene ether in the composite aqueous phase is (21-30):1, the demulsification time of cationic modified emulsified asphalt in cold-mix asphalt mixture is 1-2 min.

2. The cold-mix asphalt mixture according to claim 1, characterized in that, The raw material of the cationic modified emulsified asphalt in the cold-mix asphalt mixture is waste tire rubber powder with a particle size of 40 mesh; the rubber hydrocarbon content in the rubber powder is 55%-60%; the carbon black content is 30%-35%; and the ash content is 5%-8%.

3. The cold-mix asphalt mixture according to claim 1, characterized in that, The water used in the composite aqueous phase of the cold-mix asphalt mixture is either tap water or mixing water.

4. The cold-mix asphalt mixture according to claim 1, characterized in that, The cationic modified emulsified asphalt in the cold-mix asphalt mixture is prepared through the following steps: (1) Preparation of modified asphalt: After heating the base asphalt to 160°C-170°C, it was transferred to an oil bath. Linear SBS modifier was added to the oil bath and stirred evenly to obtain a mixture. First, the mixture is sheared at a shear rate of 2000-3000 rpm for 60-90 min; Then, reduce the shear rate to 150-200 rpm, add the rubber powder, and shear for 5-10 minutes; then increase the shear rate to 3000-4000 rpm, continue shearing for 30-45 minutes, and then add industrial sulfur powder. Finally, reduce the shear rate to 150-200 rpm and shear for 30-40 minutes to obtain the modified asphalt, and keep it at 160-170℃ for later use. (2) Preparation of composite aqueous phase: First, heat the water to 65-80℃, then add sodium tripolyphosphate and stir until the sodium tripolyphosphate is completely dissolved. Then, add hydroxyethylhexadecyl dimethyl ammonium chloride and continue stirring until completely dissolved; Add glacial acetic acid dropwise to adjust the pH of the solution to 2.0-3.0; Add hydroxypropyl methylcellulose and stir for 20-30 minutes until completely dissolved. Then add alkylphenol polyoxyethylene ether and continue stirring for 5-10 minutes to obtain the composite aqueous phase. (3) Preparation of cationic modified emulsified asphalt: First, the obtained composite aqueous phase is put into a colloid mill for circulation treatment, wherein the colloid mill speed is 1000-1500 rpm and the circulation time is 3-5 min; Then, increase the speed of the colloid mill to 3000-5000 rpm, and ensure the inlet pressure is 0.10-0.20 MPa; add the obtained modified asphalt into the colloid mill for mixing, and control the outlet temperature at 90-95℃; Finally, the material is discharged and cooled to below 65°C, left to stand and mature for 12-24 hours, and then sieved through a 100-mesh sieve before being placed into a container to obtain the cationic modified emulsified asphalt.

5. The cold-mix asphalt mixture according to claim 4, characterized in that, In the preparation step (1) of the cationic modified emulsified asphalt in the cold-mix asphalt mixture, the stirring speed of the linear SBS modifier and the base asphalt is 200-300 rpm, and the stirring time is 20-30 min.

6. The cold-mix asphalt mixture according to claim 1, characterized in that, The residual content difference between the upper and lower layers of the cationic modified emulsified asphalt in the cold-mix asphalt mixture after 1 day of storage is ≤0.7%; the residual content difference between the upper and lower layers after 5 days of storage is ≤1.5%; and the Seybert viscosity of the cationic modified emulsified asphalt is 87-216s.

7. The cold-mix asphalt mixture according to claim 1, characterized in that, The cold-mixed asphalt mixture has a Marshall stability value of 10.0-10.7 kN, a dynamic stability of 8700-9200 cycles / mm, and a freeze-thaw splitting strength ratio of 94.0-97.6%.

8. A method for preparing cold-mix asphalt mixture as described in any one of claims 1-7, characterized in that, Includes the following steps: First, the aggregate and mineral powder prepared according to the particle size distribution are put into the mixer and stirred for 15-30 seconds at a stirring speed of 60-120 rpm. After mixing evenly, add a portion of the mixing water for wet mixing, which should take 15-30 seconds; this portion of mixing water should account for 70%-80% of the total weight of the mixing water. Then, the cationic modified emulsified asphalt is added within 15-30 seconds; the remaining mixing water is added and stirring is continued for 60-90 seconds to obtain the cold-mix asphalt mixture.

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