Polymer emulsion preparation method, sand-type cold-mix cover material and paving method
By preparing composite modified polymer emulsions and high-viscosity emulsified asphalt binders, the problems of poor interlayer bonding performance and insufficient anti-skid durability in cold-laid maintenance technology have been solved, achieving efficient and low-noise road maintenance and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQINGSHI ZHIXIANG PAVING TECH ENG CO LTD
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-05
AI Technical Summary
Existing cold-laid curing technologies suffer from problems such as poor interlayer bonding performance, insufficient anti-slip durability, high construction noise, poor flatness, and high cost.
A polymer emulsion preparation method was adopted, and a composite modified polymer emulsion was prepared by modifying it with graphene oxide and titanium dioxide. Combined with wide temperature range emulsified asphalt and semi-flexible filler, a high viscosity emulsified asphalt binder was formed, which improved the interlayer bonding performance and anti-skid durability.
It improves the interlayer bonding performance and anti-slip durability of cold-laid curing technology, reduces construction noise, reduces energy consumption and costs, and enhances high and low temperature performance and the adhesion of the binder.
Smart Images
Figure CN122145964A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of road maintenance technology, specifically to a method for preparing a polymer emulsion, a sand-type cold-mix overlay mixture, and a paving method. Background Technology
[0002] With the slowdown in new highway construction in recent years, the proportion of maintenance mileage has gradually increased, especially for toll highways. Major and minor repairs to "aged" or "high-aged" highways require high initial investments. Adopting low-carbon, low-disruption preventative maintenance technologies to extend road surface lifespan and postpone major and minor repair schedules has become an industry trend. Current preventative maintenance technologies mainly include ultra-thin overlays, micro-surfacing, and skid seals. Ultra-thin overlays are favored for their good overall performance, but their application is limited by high emissions of waste smoke and gas during construction, high energy consumption, and restrictions on weight and height restrictions in certain road sections. High costs also put financial pressure on maintenance departments. Traditional micro-surfacing technology is the most widely used preventative maintenance technology in China due to its fast construction and cold application, resulting in low overall cost. However, it also suffers from typical problems such as poor interlayer adhesion, high noise, poor smoothness, and insufficient skid resistance and durability. Skid seals are very thin and can quickly restore skid resistance, but issues such as nozzle overlap during construction and ruts on the original road surface causing oil seepage and delamination in the wheel tracks, as well as rapid crack reflection, exist. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this invention proposes a polymer emulsion preparation method, a sand-type cold-mix overlay compound, and a paving method, aiming to improve the bonding performance between cold-laid curing layers and enhance the anti-slip durability of cold-laid curing layers.
[0004] In a first aspect, embodiments of this application provide a method for preparing a polymer emulsion, comprising: (1) Polyvinyl alcohol modified graphene oxide was obtained based on graphene oxide, polyvinyl alcohol and deionized water. (2) Based on deionized water, sodium hydroxide, dopamine and nano titanium dioxide, dopamine-modified titanium dioxide was obtained; (3) Based on the catalyst, toluene, pentamethylene diisocyanate and phosphoric acid, pentamethylene diisocyanate trimer was obtained; (4) Add pentamethylene diisocyanate trimer to cashew shell liquid and stir to obtain bio-based polyurethane prepolymer; (5) Dissolve the hydrophilic chain extender in N-methylpyrrolidone, add the bio-based polyurethane prepolymer, heat and stir; add the small molecule chain extender to react; add the trifunctional crosslinking agent, maintain the reaction temperature and stir, and after cooling, add triethylamine to neutralize the reaction. After cooling to room temperature, add polyvinyl alcohol modified graphene oxide, dopamine modified titanium dioxide and deionized water to emulsify and disperse, remove the residual solvent, and obtain an aqueous polyurethane emulsion. (6) Add the waterborne bio-based polyurethane emulsion to the nonionic SBS latex and stir; when the waterborne bio-based polyurethane emulsion is added, place it in a high-speed shearing machine for shearing, and then add a stabilizer and stir to obtain a composite modified polymer emulsion.
[0005] Optionally, the composite modified polymer emulsion is derived from SBS latex by modifying a bio-based polyurethane prepolymer emulsion. This composite modified polymer emulsion not only possesses excellent high and low temperature performance and crack resistance, but also effectively enhances the system's adhesion and abrasion resistance. The high-viscosity modified emulsified asphalt formed by adding the composite modified polymer emulsion is required to have a solid content ≥61%, a slow-cracking, fast-setting demulsification rate, a cationic charge, an evaporation residue softening point ≥75℃, a ductility at 5℃ ≥35cm, an elastic recovery rate ≥85%, a dynamic viscosity ≥20000Pa·s, a shear strength at 25℃ ≥0.7MPa, and a pull-out strength ≥0.5MPa.
[0006] Optionally, step (1) includes: Graphene oxide was added to deionized water and ultrasonically dispersed for 0.5–2 h to form a graphene oxide suspension. Polyvinyl alcohol was added to deionized water, heated to 80–110 °C, and continuously stirred to dissolve, resulting in a polyvinyl alcohol aqueous solution. The graphene oxide suspension and the polyvinyl alcohol aqueous solution were mixed and ultrasonically dispersed for 0.5–2 h to form a polyvinyl alcohol-modified graphene oxide mixture. The polyvinyl alcohol-modified graphene oxide mixture was vacuum filtered, and the polyvinyl alcohol-modified graphene oxide composite was washed multiple times with anhydrous ethanol and vacuum dried at 50–70 °C for 12–48 h. After thorough grinding, polyvinyl alcohol-modified graphene oxide was obtained.
[0007] Optionally, step (2) includes: Deionized water was added to sodium hydroxide and heated to 50-70°C. Dopamine was added and stirred until homogeneous. Nano-titanium dioxide was added and stirred continuously at 50-70°C for 2-5 hours. After vacuum filtration, the mixture was washed multiple times with anhydrous ethanol and dried at 50-70°C for 10-40 hours. Finally, it was thoroughly ground to obtain dopamine-modified titanium dioxide.
[0008] Optionally, step (3) includes: The catalyst was dissolved in toluene to prepare a catalyst solution; the catalyst was slowly added dropwise to pentamethylene diisocyanate at 50-60℃ and stirred continuously for 4-10 hours; phosphoric acid was added and stirred for 0.2-2 hours, and then the excess aprotic solvent and polyisocyanate were removed by distillation to obtain pentamethylene diisocyanate trimer.
[0009] Optionally, step (4) includes: Cashew shell liquid is heated to 100-150℃ to remove water for 0.2-2 hours, then cooled to 70-90℃. Pentamethylene diisocyanate trimer is added dropwise under nitrogen protection and stirred for 0.5-2 hours to obtain bio-based polyurethane prepolymer.
[0010] Optionally, step (5) includes: A hydrophilic chain extender was dissolved in N-methylpyrrolidone, and a bio-based polyurethane prepolymer was added. The mixture was heated to 70-90°C and stirred for 2-5 hours. A small molecule chain extender and acetone were added, and the reaction was carried out for 0.5-2 hours. A trifunctional crosslinking agent was added, and the reaction temperature was maintained while stirring for 0.5-2 hours. After cooling to 30-50°C, triethylamine was added for neutralization reaction for 0.2-2 hours. After cooling to room temperature, polyvinyl alcohol-modified graphene oxide, dopamine-modified titanium dioxide, and deionized water were added and emulsified and dispersed at 1200-1800 r / min for 0.5-2 hours. The residual solvent was removed by rotary evaporation to obtain an aqueous polyurethane emulsion.
[0011] The small molecule chain extender is 1,4-butanediol. The trifunctional crosslinking agent is trimethylolpropane. The hydrophilic chain extender is dimethylolpropionic acid.
[0012] Optionally, step (6) includes: A waterborne bio-based polyurethane emulsion with a solid content of 30-70% is added to an SBS latex with a solid content of 30-70% at a flow rate of 5-15 ml / min, while maintaining a temperature of 18-35℃ and stirring. After the waterborne bio-based polyurethane emulsion is completely added, it is placed in a high-speed shearing machine and sheared for 10-40 min. A stabilizer is added, and the mixture is stirred at a speed of 400-600 r / min to obtain a composite modified polymer emulsion.
[0013] The SBS latex is a nonionic SBS latex. The stabilizer is carboxymethyl cellulose.
[0014] Secondly, embodiments of this application provide a sand-type cold-mix overlay mixture, comprising the following components by weight: 10-14 parts of wide-temperature-range emulsified asphalt; 0.8-1.2 parts of composite modified water-based polymer emulsion prepared according to any one of claims 1 to 7; 55-100 parts of 3-5mm coarse aggregate; 0-45 parts of 0-3mm fine aggregate; 0-5 parts of semi-flexible filler; and 0-3 parts of water.
[0015] Optionally, the wide temperature range emulsified asphalt comprises the following materials in parts by weight: 60-65 parts base asphalt; 35-40 parts water; 1.6-2.4 parts surfactant; 1.3-1.9 parts hydrochloric acid with a concentration of 35%; and 0.1-0.3 parts defoamer.
[0016] Optionally, the 3-5mm coarse aggregate is hard basalt or diabase, and the 0-3mm fine aggregate is limestone manufactured sand; the 3-5mm coarse aggregate serves as the main skeleton of the mixture, and the 0-3mm fine aggregate is used for filling, which effectively increases the internal friction resistance of the mixture and reduces the loss of the skeleton structure formed by a single particle size due to continuous slippage caused by the vehicle's movement.
[0017] Optionally, the filler is a semi-flexible filler composed of ordinary silicate cement of grade 42.5 and 80-mesh waste rubber powder after vulcanization treatment in a mass ratio of 1:1. On the one hand, it promotes the formation of early strength of cold-mixed micro-covered surface mixture through cement hydration reaction, and on the other hand, the rubber powder can be dispersed in the skeleton voids through mixing to provide the system with deformation capacity.
[0018] Thirdly, embodiments of this application provide a method for constructing a cold-mixed sand-based overlay, including: The original road surface should be thoroughly treated using appropriate methods; The wide temperature range emulsified asphalt as described in claim 8 or 9 and the modified water-based polymer emulsion are mixed by stirring to form high viscosity emulsified asphalt. The binder (high viscosity emulsified asphalt), 3-5mm coarse aggregate, 0-3mm fine aggregate, semi-flexible filler and water are loaded into a cold paving vehicle according to the weight parts. The spiral mixing speed of the paving box of the cold-mix paving vehicle is 60~100r / min. When the sand-type cold-mix overlay mixture flows into 1 / 2 to 2 / 3 of the volume of the paving box, start the paving vehicle and drive at a constant speed of 15m / min~25m / min to pave. The paving thickness is 6~10mm. The first curing is carried out after the road section is paved, and the state of the slurry mixture gradually changes from brown to black. Once the paving conditions are met, a release agent is sprayed and the surface is simultaneously compacted by a road roller to complete the paving of the sand-type cold-mix overlay.
[0019] This application uses polyvinyl alcohol to modify graphene oxide to prepare a composite modified polymer emulsion, which solves the problem of aggregation of traditional nanoparticles.
[0020] This application uses dopamine-modified titanium dioxide to prepare a composite modified polymer emulsion, which improves the aging resistance and adhesion of high-viscosity emulsified asphalt binder.
[0021] This application utilizes two nanomaterials, graphene oxide and titanium dioxide, to enhance the performance of high-viscosity emulsified asphalt binder.
[0022] This application improves construction adaptability and opening speed under different environmental conditions by controlling the core materials.
[0023] The beneficial effects of the present invention are as follows: (1) Wide temperature range emulsified asphalt is prepared by blending polyamide and lignin surfactants, which can effectively adjust the molding time under different temperature conditions. (2) By adding composite modified polymer emulsion to emulsified asphalt to form high viscosity emulsified asphalt, the high and low temperature performance and elastic recovery ability are effectively improved, while the adhesion ability of binder and aggregate and the bonding ability of sand-type cold-mix overlay mixture with the original road surface are enhanced, and the wear resistance of asphalt film is enhanced. (3) The design adopts a dense skeleton gradation, and cement and rubber powder are added as semi-flexible fillers. The voids are wrapped with micro powder elastomer, which can effectively enhance the crack resistance, prevent crack reflection, provide anti-skid durability, and reduce noise. (4) The present invention adopts cold construction, avoiding the emission problem of flue gas at the construction site of hot-mix asphalt mixture. At the same time, the cost is reduced by about 30% compared with hot-mix ultra-thin overlay throughout the entire life cycle. Attached Figure Description
[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.
[0025] Figure 1 This is a schematic flowchart of a polymer emulsion preparation method provided in an embodiment of this application. Detailed Implementation
[0026] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.
[0027] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values listed herein include the endpoints of the range and all integers and fractions within that range.
[0028] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.
[0029] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.
[0030] Unless otherwise specified, all raw materials or reagents in the following embodiments can be obtained through commercial purchases or prepared using conventional methods in the art.
[0031] In the following embodiments, the equipment used for high-speed shearing is a DBR-4 high-shear emulsifier, purchased from Changzhou Daruiyi Machinery Equipment Technology Co., Ltd. Example 1
[0032] This embodiment provides a sand-type cold-mix overlay mixture, comprising 100 parts of 3-5mm coarse basalt coarse aggregate, 0 parts of 0-3mm limestone fine aggregate, 12 parts of wide-temperature-range emulsified asphalt, 1.2 parts of modified water-based polymer emulsion, 5 parts of semi-flexible filler, and 2 parts of water, mixed in a certain order of addition.
[0033] I. The wide-temperature-range emulsified asphalt comprises the following parts by weight: 60 parts base asphalt, 40 parts water, 2 parts lignin-based and polyamide-based blended surfactant, 1.9 parts hydrochloric acid, and 0.2 parts defoamer. The preparation process is as follows: (1) Heat the base asphalt to 138°C for later use; (2) Add lignin-based and polyamide-based surfactants in a 1:1 ratio to water at 50°C and stir to form soap solution. Add 35% hydrochloric acid to make the pH of the soap solution 2.
[0034] (3) First, pour the soap solution into the colloid mill and shear for 1 minute. Then, add the flowing matrix asphalt to the circulating soap solution at a uniform speed. When the amount of asphalt added reaches the predetermined oil-water ratio, stop adding. Take a sample after shearing for 1 minute.
[0035] II. The composite modified polymer emulsion (polymer emulsion) comprises the following parts by weight: 6 parts nonionic SBS latex, 4 parts nonionic waterborne bio-based polyurethane emulsion. The preparation method of the composite modified polymer emulsion includes the following steps: (1) Weigh 10 parts of graphene oxide (GO) and add it to 200 parts of deionized water. Disperse it by ultrasonication for 1 hour to form a uniformly dispersed GO suspension. Then, weigh 10 parts of polyvinyl alcohol (PVA) and add it to 100 parts of deionized water. Heat the mixture to 95°C and stir continuously to dissolve it to obtain a PVA aqueous solution. Next, mix the GO suspension and the PVA aqueous solution and disperse it by ultrasonication for 1 hour to form a PVA-GO mixture. Finally, filter the mixture under vacuum, wash the PVA-GO composite three times with anhydrous ethanol, and dry it under vacuum at 60°C for 24 hours. Grind it thoroughly to obtain polyvinyl alcohol modified graphene oxide, which is PVA-GO.
[0036] (2) Weigh 40 parts of sodium hydroxide (NaOH) into a beaker, add 1000 parts of deionized water, and heat to 60°C; then, weigh 20 parts of dopamine, add to the beaker, stir evenly, add 18 parts of nano titanium dioxide, and stir continuously at 50°C for 5 hours; finally, vacuum filter the product, wash it five times with anhydrous ethanol, put it in a 70°C oven for drying for 24 hours, grind it thoroughly, and obtain dopamine-modified titanium dioxide, which is DA-TiO2.
[0037] (3) Weigh 20 parts of pentamethylene diisocyanate (PDI) into a 500 mL three-necked flask and place it in a 60°C oil bath; dissolve 0.2 parts of catalyst in 45 parts of toluene to prepare a solution, slowly add the solution dropwise under a nitrogen atmosphere and stir continuously for 10 h; then add 0.15 parts of phosphoric acid and stir continuously for 0.2 h, remove excess aprotic solvent and polyisocyanate by distillation to obtain pentamethylene diisocyanate trimer.
[0038] (4) Weigh 12 parts of cashew shell liquid into a 500 mL three-necked flask, heat to 120 °C to remove water for 2 h, then cool to 90 °C, add 40 parts of pentamethylene diisocyanate trimer under nitrogen protection, and stir continuously for 1 h to obtain bio-based polyurethane prepolymer.
[0039] (5) Weigh 0.5 parts of the hydrophilic chain extender dimethylolpropionic acid and dissolve it in 5 parts of N-methylpyrrolidone. Add 15 parts of bio-based polyurethane prepolymer, heat to 80°C, and stir continuously for 5 hours. Then add 0.3 parts of the small molecule chain extender 1,4-butanediol and continue the reaction for 1 hour. During this process, add 1 part of acetone to reduce the viscosity of the system. Then, add 0.8 parts of the trifunctional crosslinking agent trimethylolpropane, keep the reaction temperature constant, and stir for 1 hour. After cooling the system to 30°C, add 0.1 parts of triethylamine for neutralization reaction and continue for 2 hours. After cooling to room temperature, add 2 parts of PVA-GO, 1 part of DA-TiO2, and 30 parts of deionized water. Emulsify and disperse at 1800 r / min for 2 hours. Finally, remove the residual solvent by rotary evaporation to obtain a stable aqueous polyurethane emulsion with a nonionic ionic type.
[0040] (6) Add 4 parts of nonionic waterborne bio-based polyurethane emulsion with a solid content of 70% to 7 parts of nonionic SBS latex with a solid content of 70% at a flow rate of 10 ml / min. During the preparation, keep the temperature within 28°C. During this process, keep the SBS latex in a stirring state, but control the vortex. When the waterborne bio-based polyurethane emulsion is added, place it in a high-speed shear machine for shearing for 20 min. Then add 0.5 parts of carboxymethyl cellulose as a stabilizer. After stirring at a speed of 400 r / min for 10 min, the composite modified polymer emulsion is obtained.
[0041] III. The performance indicators of wide-temperature-range high-viscosity modified emulsified asphalt are shown in Table 5.
[0042] IV. The aggregate gradation composition of the cold-mixed sand-type overlay is shown in Table 1.
[0043] Table 2 Aggregate gradation composition of Example 1 V. The performance indicators of the mixed sand-type cold-mix paving material are shown in Table 6.
[0044] VI. The specific steps of the sand-based cold-mix paving method in this embodiment are as follows: (1) Before construction Before construction, the original road surface should be investigated to understand the types and causes of defects, and appropriate methods should be used to thoroughly treat them. For ruts less than 10mm, cold-mix overlay can be used directly for overlay.
[0045] If there is an anti-slip seal or micro-surfacing layer in the construction section, it should be milled in time to prevent the overlay from falling off.
[0046] (2) Spreading First, the wide temperature range emulsified asphalt and modified water-based polymer emulsion are mixed by stirring to form high viscosity emulsified asphalt. Then, the binder, aggregate, filler, water and other materials are loaded into the cold paving truck according to the weight parts. The auger mixing speed of the paving box is 100 r / min. When the sand-type cold-mix overlay mixture flows into 1 / 2 of the paving box volume, the paver is started and driven at a constant speed of 15 m / min to pave the surface. The paving thickness is 10 mm.
[0047] (3) First health preservation and crushing After the paving of the road section is completed, the first curing is carried out, and the state of the slurry mixture gradually changes from brown to black. The compaction time is determined according to the weather conditions. Before compaction, the working surface can be touched with a paper towel and rubbed lightly with your fingers. If there are no obvious water stains or black sticky substances on the paper towel, the road roller can be used for compaction. Compaction is usually carried out within 30 minutes after paving is completed.
[0048] For cold-mix overlay, it is generally recommended to use an 8-ton double rubber-tired roller. If this is not possible, a steel-rubber combination roller can be selected. The compaction speed should be 4 km / h, the roller tracks should overlap by about 30 cm, and the number of compaction passes should be 5. Roll in and out smoothly, and it is strictly forbidden to turn left or right on the working surface, or to stop abruptly. Water-based materials should be sprayed as a release agent to prevent the rollers from sticking.
[0049] (4) Second health preservation and opening of traffic After compaction, touch the work surface with a paper towel again. If there are no water stains or black sticky substances on the surface, and there is no obvious displacement or loosening when gently rubbing with your fingers, it can be opened.
[0050] If it rains or the temperature is too low after compaction, it is recommended to extend the second curing time before opening the road to traffic.
[0051] (5) Repair After the mixture is laid, local construction defects are repaired manually in a timely manner.
[0052] If the work surface during the curing period falls off due to external factors, the remaining demulsified and adhesive mixture from the paving process can be used for repair, and the surface should be repeatedly compacted. At the same time, 0-3mm manufactured sand should be spread on the repair surface to prevent it from being adhered and carried away after traffic resumes. Example 2
[0053] This embodiment provides a sand-type cold-mix overlay mixture, comprising 75 parts of 3-5mm basalt coarse aggregate, 25 parts of 0-3mm limestone fine aggregate, 14 parts of wide-temperature-range emulsified asphalt, 1 part of modified water-based polymer emulsion, 3 parts of semi-flexible filler, and 3 parts of water, which are mixed in a certain order of addition.
[0054] I. The wide-temperature-range emulsified asphalt comprises the following parts by weight: 65 parts base asphalt, 37 parts water, 1.6 parts lignin-based and polyamide-based blend surfactant, 1.5 parts hydrochloric acid, and 0.3 parts defoamer. The preparation process is as follows: (1) Heat the base asphalt to 140℃ for later use; (2) Add lignin-based and polyamide-based surfactants in a 1:1 ratio to water at 60°C and stir to form soap solution. Add 35% hydrochloric acid to make the pH of the soap solution 3.
[0055] (3) First, pour the soap solution into the colloid mill and shear for 1 minute. Then, add the flowing matrix asphalt to the circulating soap solution at a uniform speed. When the amount of asphalt added reaches the predetermined oil-water ratio, stop adding. Take a sample after shearing for 1 minute.
[0056] II. The composite modified polymer emulsion (polymer emulsion) comprises the following parts by weight: 6.5 parts nonionic SBS latex, 3.5 parts nonionic waterborne bio-based polyurethane emulsion. The preparation method of the composite modified polymer emulsion includes the following steps: (1) Weigh 15 parts of graphene oxide (GO) and add it to 180 parts of deionized water. Disperse the mixture by ultrasonication for 2 hours to form a uniformly dispersed GO suspension. Then, weigh 5 parts of polyvinyl alcohol (PVA) and add it to 80 parts of deionized water. Heat the mixture to 80°C and stir continuously to dissolve it to obtain a PVA aqueous solution. Next, mix the GO suspension and the PVA aqueous solution and disperse the mixture by ultrasonication for 2 hours to form a PVA-GO mixture. Finally, filter the mixture under vacuum, wash the PVA-GO composite four times with anhydrous ethanol, and dry it under vacuum at 50°C for 48 hours. Grind the mixture thoroughly to obtain polyvinyl alcohol modified graphene oxide, which is PVA-GO.
[0057] (2) Weigh 45 parts of sodium hydroxide (NaOH) into a beaker, add 1200 parts of deionized water, and heat to 70°C; then, weigh 25 parts of dopamine, add to the beaker, stir evenly, add 20 parts of nano titanium dioxide, and stir continuously at 70°C for 3 hours; finally, vacuum filter the product, wash it three times with anhydrous ethanol, put it in a 60°C oven to dry for 40 hours, grind it thoroughly, and obtain dopamine-modified titanium dioxide, which is DA-TiO2.
[0058] (3) Weigh 30 parts of pentamethylene diisocyanate (PDI) into a 500 mL three-necked flask and place it in an oil bath at 55°C; dissolve 0.1 parts of catalyst in 40 parts of toluene to prepare a solution, slowly add the solution dropwise under a nitrogen atmosphere and stir continuously for 6 h; then add 0.1 parts of phosphoric acid and stir continuously for 0.5 h, remove excess aprotic solvent and polyisocyanate by distillation to obtain pentamethylene diisocyanate trimer.
[0059] (4) Weigh 15 parts of cashew shell liquid into a 500 mL three-necked flask, heat to 150 °C to remove water for 0.5 h, then cool to 70 °C, add 30 parts of pentamethylene diisocyanate trimer under nitrogen protection, and stir continuously for 2 h to obtain bio-based polyurethane prepolymer.
[0060] (5) Weigh 1 part of the hydrophilic chain extender dimethylolpropionic acid and dissolve it in 10 parts of N-methylpyrrolidone. Add 10 parts of bio-based polyurethane prepolymer, heat to 90°C, and stir continuously for 3 hours. Then add 0.5 parts of the small molecule chain extender 1,4-butanediol and continue the reaction for 2 hours. During this process, add 0.8 parts of acetone to reduce the viscosity of the system. Then, add 1 part of the trifunctional crosslinking agent trimethylolpropane, keep the reaction temperature constant, and stir for 0.2 hours. After cooling the system to 40°C, add 0.2 parts of triethylamine for neutralization reaction and continue for 0.5 hours. After cooling to room temperature, add 1 part of PVA-GO, 0.5 parts of DA-TiO2, and 20 parts of deionized water. Emulsify and disperse at 1500 r / min for 1 hour. Finally, remove the residual solvent by rotary evaporation to obtain a stable waterborne polyurethane emulsion with a nonionic ionic type.
[0061] (6) Add 3.5 parts of nonionic waterborne bio-based polyurethane emulsion with a solid content of 50% to 6.5 parts of nonionic SBS latex with a solid content of 30% at a flow rate of 10 ml / min. During the preparation, keep the temperature within 35°C. During this process, keep the SBS latex in a stirring state, but control the vortex. When the waterborne bio-based polyurethane emulsion is added, place it in a high-speed shear machine for shearing for 40 min. Then add 0.4 parts of carboxymethyl cellulose as a stabilizer. After stirring at a speed of 600 r / min for 8 min, the composite modified polymer emulsion is obtained.
[0062] III. The performance indicators of wide-temperature-range high-viscosity modified emulsified asphalt are shown in Table 5.
[0063] IV. The aggregate gradation composition of the cold-mixed sand-type overlay is shown in Table 2.
[0064] Table 2 Aggregate gradation composition of Example 2 V. The performance indicators of the mixed sand-type cold-mix paving material are shown in Table 6.
[0065] VI. The specific steps of the sand-based cold-mix paving method in this embodiment are as follows: (1) Before construction Before construction, the original road surface should be investigated to understand the types and causes of defects, and appropriate methods should be used to thoroughly treat them. For ruts less than 8mm, cold-mix overlay can be used directly for overlay.
[0066] If there is an anti-slip seal or micro-surfacing layer in the construction section, it should be milled in time to prevent the overlay from falling off.
[0067] (2) Spreading First, the wide temperature range emulsified asphalt and modified water-based polymer emulsion are mixed by stirring to form high viscosity emulsified asphalt. Then, the binder, aggregate, filler, water and other materials are loaded into the cold paving truck according to the weight parts. The auger mixing speed of the paving box is 60 r / min. When the sand-type cold-mix overlay mixture flows into 2 / 3 of the paving box volume, the paver is started and driven at a constant speed of 25 m / min to pave the surface. The paving thickness is 8 mm.
[0068] (3) First health preservation and crushing After the road section is paved, the first curing is carried out, during which the slurry mixture gradually changes from brownish-black to black. The compaction time is determined according to the weather conditions. Before compaction, the working surface can be touched with a paper towel and gently rubbed with your fingers. If there are no obvious water stains or black sticky substances on the paper towel, the road roller can be used for compaction. Compaction is usually carried out within 60 minutes after paving is completed.
[0069] For cold-mix overlay, it is generally recommended to use a 10-ton double rubber-tired roller. If this is not possible, a steel-rubber combination roller can be selected. The compaction speed is 5 km / h, the roller tracks overlap is about 30 cm, and the number of compaction passes is 4. Roll in and out smoothly. Turning left or right on the working surface, sudden stops and brakes are strictly prohibited. Water-based materials should be sprayed as a release agent to prevent the rollers from sticking.
[0070] (4) Second health preservation and opening of traffic After compaction, touch the work surface with a paper towel again. If there are no water stains or black sticky substances on the surface, and there is no obvious displacement or loosening when gently rubbing with your fingers, it can be opened.
[0071] If it rains or the temperature is too low after compaction, it is recommended to extend the second curing time before opening the road to traffic.
[0072] (5) Repair After the mixture is laid, local construction defects are repaired manually in a timely manner.
[0073] If the work surface during the curing period falls off due to external factors, the remaining demulsified and adhesive mixture from the paving process can be used for repair, and the surface should be repeatedly compacted. At the same time, 3mm of manufactured sand should be spread on the repair surface to prevent it from being adhered and carried away after traffic resumes. Example 3
[0074] This embodiment provides a sand-type cold-mix overlay mixture, comprising 75 parts of 3-5mm basalt coarse aggregate, 25 parts of 0-3mm limestone fine aggregate, 14 parts of wide-temperature-range emulsified asphalt, 1 part of modified water-based polymer emulsion, 3 parts of semi-flexible filler, and 3 parts of water, which are mixed in a certain order of addition.
[0075] I. The wide-temperature-range emulsified asphalt comprises the following parts by weight: 63 parts base asphalt, 35 parts water, 2.4 parts lignin-based and polyamide-based blended surfactant, 1.3 parts hydrochloric acid, and 0.1 parts defoamer. The preparation process is as follows: (1) Heat the base asphalt to 135°C for later use; (2) Add lignin-based and polyamide-based surfactants in a 1:1 ratio to water at 55°C and stir to form soap solution. Add 35% hydrochloric acid to make the pH of the soap solution 3.
[0076] (3) First, pour the soap solution into the colloid mill and shear for 1 minute. Then, add the flowing matrix asphalt to the circulating soap solution at a uniform speed. When the amount of asphalt added reaches the predetermined oil-water ratio, stop adding. Take a sample after shearing for 1 minute.
[0077] II. The composite modified polymer emulsion (polymer emulsion) comprises the following parts by weight: 6 parts nonionic SBS latex, 3 parts nonionic waterborne bio-based polyurethane emulsion. The preparation method of the composite modified polymer emulsion includes the following steps: (1) Weigh 20 parts of graphene oxide (GO) and add it to 220 parts of deionized water. Disperse the mixture by ultrasonication for 0.5 h to form a uniformly dispersed GO suspension. Then, weigh 8 parts of polyvinyl alcohol (PVA) and add it to 120 parts of deionized water. Heat the mixture to 110°C and stir continuously to dissolve it to obtain a PVA aqueous solution. Next, mix the GO suspension and the PVA aqueous solution and disperse the mixture by ultrasonication for 0.5 h to form a PVA-GO mixture. Finally, filter the mixture under vacuum, wash the PVA-GO composite five times with anhydrous ethanol, and dry it under vacuum at 70°C for 12 h. Grind the mixture thoroughly to obtain polyvinyl alcohol modified graphene oxide, which is PVA-GO.
[0078] (2) Weigh 50 parts of sodium hydroxide (NaOH) into a beaker, add 1100 parts of deionized water, and heat to 50°C; then, weigh 30 parts of dopamine, add to the beaker, stir evenly, add 15 parts of nano titanium dioxide, and stir continuously at 60°C for 2 hours; finally, vacuum filter the product, wash it four times with anhydrous ethanol, put it in a 50°C oven to dry for 10 hours, grind it thoroughly, and obtain dopamine-modified titanium dioxide, which is DA-TiO2.
[0079] (3) Weigh 25 parts of pentamethylene diisocyanate (PDI) into a 500 mL three-necked flask and place it in a 50°C oil bath; dissolve 0.3 parts of catalyst in 50 parts of toluene to prepare a solution, slowly add the solution dropwise under a nitrogen atmosphere and stir continuously for 4 h; then add 0.2 parts of phosphoric acid and stir continuously for 1 h, remove excess aprotic solvent and polyisocyanate by distillation to obtain pentamethylene diisocyanate trimer.
[0080] (4) Weigh 10 parts of cashew shell liquid into a 500 mL three-necked flask, heat to 100 °C to remove water for 0.2 h, then cool to 80 °C, add 35 parts of pentamethylene diisocyanate trimer under nitrogen protection, and stir continuously for 0.5 h to obtain bio-based polyurethane prepolymer.
[0081] (5) Weigh 0.7 parts of the hydrophilic chain extender dimethylolpropionic acid and dissolve it in 7 parts of N-methylpyrrolidone. Add 12 parts of bio-based polyurethane prepolymer, heat to 70°C, and stir continuously for 2 hours. Then add 0.4 parts of the small molecule chain extender 1,4-butanediol and continue the reaction for 0.5 hours. During this process, add 1.2 parts of acetone to reduce the viscosity of the system. Then add 0.5 parts of the trifunctional crosslinking agent trimethylolpropane, keep the reaction temperature constant, and stir for 2 hours. After cooling the system to 50°C, add 0.15 parts of triethylamine for neutralization reaction and continue for 0.2 hours. After cooling to room temperature, add 1.5 parts of PVA-GO, 0.8 parts of DA-TiO2, and 25 parts of deionized water. Emulsify and disperse at 1200 r / min for 0.5 hours. Finally, remove the residual solvent by rotary evaporation to obtain a stable waterborne polyurethane emulsion with a nonionic ionic type.
[0082] (6) Add 3 parts of nonionic waterborne bio-based polyurethane emulsion with a solid content of 30% to 6 parts of nonionic SBS latex with a solid content of 50% at a flow rate of 10 ml / min. During the preparation, keep the temperature within the range of 18°C. During this process, keep the SBS latex in a stirring state, but control the vortex. When the waterborne bio-based polyurethane emulsion is added, place it in a high-speed shear machine and shear for 10 min. Then add 0.2 parts of carboxymethyl cellulose as a stabilizer. After stirring at a speed of 500 r / min for 15 min, the composite modified polymer emulsion is obtained.
[0083] III. The performance indicators of wide-temperature-range high-viscosity modified emulsified asphalt are shown in Table 5.
[0084] IV. The aggregate gradation composition of the cold-mixed sand-type overlay is shown in Table 3.
[0085] Table 3 Aggregate gradation composition of Example 3 V. The performance indicators of the mixed sand-type cold-mix paving material are shown in Table 6.
[0086] VI. The specific steps of the sand-based cold-mix paving method in this embodiment are as follows: (1) Before construction Before construction, the original road surface should be investigated to understand the types and causes of defects, and appropriate methods should be used to thoroughly treat them. For ruts less than 6mm, cold-mix overlay can be used directly for overlay.
[0087] If there is an anti-slip seal or micro-surfacing layer in the construction section, it should be milled in time to prevent the overlay from falling off.
[0088] (2) Spreading First, the wide temperature range emulsified asphalt and modified water-based polymer emulsion are mixed by stirring to form high viscosity emulsified asphalt. Then, the binder, aggregate, filler, water and other materials are loaded into the cold paving truck according to the weight parts. The auger mixing speed of the paving box is 80 r / min. When the sand-type cold-mix overlay mixture flows into 3 / 5 of the paving box volume, the paver is started and driven at a constant speed of 20 m / min to pave the surface. The paving thickness is 6 mm.
[0089] (3) First health preservation and crushing After the paving of the road section is completed, the first curing is carried out, and the state of the slurry mixture gradually changes from brown to black. The compaction time is determined according to the weather conditions. Before compaction, the working surface can be touched with a paper towel and rubbed lightly with your fingers. If there are no obvious water stains or black sticky substances on the paper towel, the road roller can be used for compaction. Compaction is usually carried out within 45 minutes after paving is completed.
[0090] For cold-mix overlay, it is generally recommended to use a 5-ton double rubber-tired roller. If this is not possible, a steel-rubber combination roller can be selected. The compaction speed is 3 km / h, the roller tracks overlap by about 30 cm, and the number of compaction passes is 3. Roll in and out smoothly. Turning left or right on the working surface, sudden stops and brakes are strictly prohibited. Water-based materials should be sprayed as a release agent to prevent the rollers from sticking.
[0091] (4) Second health preservation and opening of traffic After compaction, touch the work surface with a paper towel again. If there are no water stains or black sticky substances on the surface, and there is no obvious displacement or loosening when gently rubbing with your fingers, it can be opened.
[0092] If it rains or the temperature is too low after compaction, it is recommended to extend the second curing time before opening the road to traffic.
[0093] (5) Repair After the mixture is laid, local construction defects are repaired manually in a timely manner.
[0094] If the work surface during the curing period falls off due to external factors, the remaining demulsified and adhesive mixture from the paving process can be used for repair, and the surface should be repeatedly compacted. At the same time, 1mm of manufactured sand should be spread on the repair surface to prevent it from being adhered and carried away after traffic resumes.
[0095] Comparative Example 1 A sand-type cold-mix overlay mixture is prepared by mixing 75 parts of basalt coarse aggregate, 25 parts of limestone fine aggregate, 12 parts of SBS modified emulsified asphalt, 1 part of cement, and 2 parts of water in a certain order of addition.
[0096] The performance indicators of SBS modified emulsified asphalt are shown in Table 5, and the performance indicators of sand-type cold-mix overlay are shown in Table 6. The specific steps of the paving process in this invention are as described in Example 1.
[0097] Comparative Example 2 A sand-type cold-mix overlay mixture is prepared by mixing 75 parts of basalt coarse aggregate, 25 parts of limestone fine aggregate, 12 parts of SBR modified emulsified asphalt, 1 part of cement, and 2 parts of water in a certain order of addition.
[0098] The performance indicators of SBR modified emulsified asphalt are shown in Table 5, and the performance indicators of sand-type cold-mix overlay are shown in Table 6. The specific steps of the paving process in this invention are as described in Example 1.
[0099] Comparative Example 3 A micro-surfacing mixture is prepared by mixing 55 parts of basalt coarse aggregate, 45 parts of limestone fine aggregate, 12 parts of matrix emulsified asphalt, 4 parts of SBR latex, 2 parts of cement, and 6 parts of water in a certain order of addition.
[0100] The gradation is shown in Table 4, the performance indicators of SBR latex modified emulsified asphalt are shown in Table 5, the performance indicators of sand-type cold-mix overlay are shown in Table 6, and the construction process shall be carried out in accordance with relevant specifications.
[0101] Table 4. Aggregate gradation composition of Comparative Example 3 The technical performance indicators of the wide-temperature-range high-viscosity modified emulsified asphalt obtained in each example and the comparative example are shown in Table 5.
[0102] Table 5 Comparison of Technical Indicators of Emulsified Asphalt Table 6 Comparison of Mixture Indicators The above test results show that the sand-type cold-mix overlay mixture of the present invention not only takes into account the traditional road performance, but also effectively enhances the interlayer bonding performance and crack resistance through the invention of a new type of binder and a reasonable gradation design, which promotes the extension of the original pavement service life.
[0103] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. A method for preparing a polymer emulsion, characterized in that, include: (1) Polyvinyl alcohol modified graphene oxide was obtained based on graphene oxide, polyvinyl alcohol and deionized water. (2) Based on deionized water, sodium hydroxide, dopamine and nano titanium dioxide, dopamine-modified titanium dioxide was obtained; (3) Based on the catalyst, toluene, pentamethylene diisocyanate and phosphoric acid, pentamethylene diisocyanate trimer was obtained; (4) Add pentamethylene diisocyanate trimer to cashew shell liquid and stir to obtain bio-based polyurethane prepolymer; (5) Dissolve the hydrophilic chain extender in N-methylpyrrolidone, add the bio-based polyurethane prepolymer, heat and stir; add the small molecule chain extender to react; add the trifunctional crosslinking agent, maintain the reaction temperature and stir, and after cooling, add triethylamine to neutralize the reaction. After cooling to room temperature, add polyvinyl alcohol modified graphene oxide, dopamine modified titanium dioxide and deionized water to emulsify and disperse, remove the residual solvent, and obtain an aqueous polyurethane emulsion. (6) Add the waterborne bio-based polyurethane emulsion to the nonionic SBS latex and stir; when the waterborne bio-based polyurethane emulsion is added, place it in a high-speed shearing machine for shearing, and then add a stabilizer and stir to obtain a composite modified polymer emulsion.
2. The method for preparing polymer emulsion according to claim 1, characterized in that, Step (1) includes: Graphene oxide was added to deionized water and ultrasonically dispersed for 0.5–2 h to form a graphene oxide suspension. Polyvinyl alcohol was added to deionized water, heated to 80–110 °C, and continuously stirred to dissolve, resulting in a polyvinyl alcohol aqueous solution. The graphene oxide suspension and the polyvinyl alcohol aqueous solution were mixed and ultrasonically dispersed for 0.5–2 h to form a polyvinyl alcohol-modified graphene oxide mixture. The polyvinyl alcohol-modified graphene oxide mixture was vacuum filtered, and the polyvinyl alcohol-modified graphene oxide composite was washed multiple times with anhydrous ethanol and vacuum dried at 50–70 °C for 12–48 h. After thorough grinding, polyvinyl alcohol-modified graphene oxide was obtained.
3. The method for preparing polymer emulsion according to claim 1, characterized in that, Step (2) includes: Deionized water was added to sodium hydroxide and heated to 50-70°C. Dopamine was added and stirred until homogeneous. Nano-titanium dioxide was added and stirred continuously at 50-70°C for 2-5 hours. After vacuum filtration, the mixture was washed multiple times with anhydrous ethanol and dried at 50-70°C for 10-40 hours. Finally, it was thoroughly ground to obtain dopamine-modified titanium dioxide.
4. The method for preparing polymer emulsion according to claim 1, characterized in that, Step (3) includes: The catalyst was dissolved in toluene to prepare a catalyst solution; the catalyst was slowly added dropwise to pentamethylene diisocyanate at 50-60℃ and stirred continuously for 4-10 hours; phosphoric acid was added and stirred for 0.2-2 hours, and then the excess aprotic solvent and polyisocyanate were removed by distillation to obtain pentamethylene diisocyanate trimer.
5. The method for preparing polymer emulsion according to claim 1, characterized in that, Step (4) includes: Cashew shell liquid is heated to 100-150℃ to remove water for 0.2-2 hours, then cooled to 70-90℃. Pentamethylene diisocyanate trimer is added dropwise under nitrogen protection and stirred for 0.5-2 hours to obtain bio-based polyurethane prepolymer.
6. The method for preparing polymer emulsion according to claim 1, characterized in that, Step (5) includes: A hydrophilic chain extender was dissolved in N-methylpyrrolidone, and a bio-based polyurethane prepolymer was added. The mixture was heated to 70-90°C and stirred for 2-5 hours. A small molecule chain extender and acetone were added, and the reaction was carried out for 0.5-2 hours. A trifunctional crosslinking agent was added, and the reaction temperature was maintained while stirring for 0.5-2 hours. After cooling to 30-50°C, triethylamine was added for neutralization reaction for 0.2-2 hours. After cooling to room temperature, polyvinyl alcohol-modified graphene oxide, dopamine-modified titanium dioxide, and deionized water were added and emulsified and dispersed at 1200-1800 r / min for 0.5-2 hours. The residual solvent was removed by rotary evaporation to obtain an aqueous polyurethane emulsion.
7. The method for preparing polymer emulsion according to claim 1, characterized in that, Step (6) includes: A waterborne bio-based polyurethane emulsion with a solid content of 30-70% is added to an SBS latex with a solid content of 30-70% at a flow rate of 5-15 ml / min, while maintaining a temperature of 18-35℃ and stirring. After the waterborne bio-based polyurethane emulsion is completely added, it is placed in a high-speed shearing machine and sheared for 10-40 min. A stabilizer is added, and the mixture is stirred at a speed of 400-600 r / min to obtain a composite modified polymer emulsion.
8. A sand-based cold-mix surface coating mixture, characterized in that, The product comprises the following components by weight: 10-14 parts of wide-temperature-range emulsified asphalt; 0.8-1.2 parts of composite modified water-based polymer emulsion prepared according to any one of claims 1 to 7; 55-100 parts of 3-5mm coarse aggregate; 0-45 parts of 0-3mm fine aggregate; 0-5 parts of semi-flexible filler; and 0-3 parts of water.
9. The sand-type cold-mix surface coating mixture according to claim 8, characterized in that, The wide temperature range emulsified asphalt comprises the following materials in parts by weight: 60-65 parts base asphalt; 35-40 parts water; 1.6-2.4 parts surfactant; 1.3-1.9 parts hydrochloric acid with a concentration of 35%; and 0.1-0.3 parts defoamer.
10. A method for constructing a cold-mixed sand-based overlay surface, characterized in that, include: The original road surface should be thoroughly treated using appropriate methods; The wide temperature range emulsified asphalt as described in claim 8 or 9 and the modified water-based polymer emulsion are mixed by stirring to form high viscosity emulsified asphalt. The high viscosity emulsified asphalt, 3-5mm coarse aggregate, 0-3mm fine aggregate, semi-flexible filler and water are loaded into a cold paving vehicle according to the weight parts. The spiral mixing speed of the paving box of the cold-mix paving vehicle is 60~100r / min. When the sand-type cold-mix overlay mixture flows into 1 / 2 to 2 / 3 of the volume of the paving box, start the paving vehicle and drive at a constant speed of 15m / min~25m / min to pave. The paving thickness is 6~10mm. The first curing is carried out after the road section is paved, and the state of the slurry mixture gradually changes from brown to black. Once the paving conditions are met, a release agent is sprayed and the surface is simultaneously compacted by a road roller to complete the paving of the sand-type cold-mix overlay.