Asphalt mixture modifier, modified asphalt paving mixture, its preparation process, its use in paving roads, paving roads and a system for preparing asphalt mixture modifiers

Abstract

The present invention relates to an asphalt mixture modifier, comprising asphalt, polyol, surfactant, mineral acid and water. The present invention also relates to a modified asphalt paving mixture comprising asphalt, aggregate and the above asphalt mixture modifier. The asphalt mixture modifier is used as an additive to solve the problems related to asphalt paving compositions in the prior art, which require the rapid in-situ use of asphalt compositions. The additive helps to prepare a modified asphalt paving mixture that can be stored for a longer time at ambient temperature, wherein the additive can be added to the mixture of aggregate and asphalt at ambient temperature. Before being applied to the road surface, it is heated to a temperature range of 130°C to 170°C, wherein all necessary characteristics are maintained for proper application to the road surface.

Description

Technical Field

[0001] The present invention relates to an asphalt mixture modifier for use as an additive in a modified asphalt paving mixture. The present invention also relates to a modified asphalt mixture and a process for its preparation, wherein the composition is an asphalt paving composition for paving a road surface. Background Art

[0002] A paving composition made of asphalt can be prepared in a factory where aggregates and asphalt are mixed and heated into a composite mixture. The asphalt plant can be a fixed plant or a mobile mixing plant. The preparation temperature of the hot asphalt mixture in the asphalt plant is generally between 130°C and 180°C.

[0003] Several asphalt paving compositions known in the prior art for use as hot asphalt mixtures are characterized in that the storage of the prepared batches of hot asphalt mixture is not feasible because the hardness of the material may exceed the required specified value, making it impossible to properly pave the road surface. Therefore, multiple asphalt plants are installed near the road surface to be paved, or multiple mobile mixing plants are put into use, resulting in fewer batches prepared according to the specific quantity of paving composition used on site, leading to relatively high associated fixed and variable preparation costs. In addition, the need to put multiple asphalt plants into use may cause some environmental damage.

[0004] In order to establish an alternative to the operation of multiple asphalt plants, International Patent Application WO2014128517A1 (Aniser Corp. LCC, August 28, 2014, abstract and description) aims to develop an asphalt paving composition including an additive component that allows for a longer storage period of the prepared asphalt paving composition. However, the additive composition disclosed in WO2014128517A1 has a very high dynamic viscosity value measured at 60°C, approximately 200,000 cP (200 Pa·s), which makes the handling and mixing of the additive composition in the final asphalt mixture difficult. In order to enable proper mixing, a heating step of the additive composition is required, in which the temperature of the additive should be raised to at least 80°C. The first disadvantage of the heating step of the additive is that in order for the additive to have sufficient fluidity to be added to the composite mixture of aggregates and asphalt, the process requires additional energy input, making the final operating cost higher and requiring more complex equipment. Another disadvantage refers to the adverse evolution of the contaminants present in the additive, which mainly come from the condensed carbon components treated in the form of very fine particles or dust. Therefore, the process disclosed in WO2014128517A1 requires the installation of further equipment to retain these contaminants to mitigate coal pollution, but it leads to an increase in the operating cost of the factory. Summary of the Invention

[0005] Accordingly, there is a great interest and need for an additive to be added to a composite mixture of aggregate and asphalt (asphalt mixture) that allows for long-term storage while maintaining its technical properties, keeping it loose and manageable at room temperature, and making its preparation process technically and economically viable without the need to install multiple fixed or mobile asphalt mixing plants. Additionally, there is a great interest and need for an additive that can be processed in a more efficient and environmentally safe manner within the ambient temperature range.

[0006] In a first aspect, the present invention relates to an asphalt mixture modifier comprising:

[0007] a. Asphalt having a dynamic viscosity of equal to or greater than 35,000 cP (35 Pa·s) and an API gravity of equal to or greater than 10 degrees, measured at 60°C, wherein the amount of the asphalt is 50 - 75% of the total weight of the asphalt mixture modifier;

[0008] b. A polyol having 2 - 8 carbon atoms, the amount of which is 2 - 6% of the total weight of the asphalt mixture modifier;

[0009] c. A surfactant, wherein the surfactant includes a cationic surfactant, a nonionic surfactant, or any combination thereof, and the amount of the surfactant is 0.05 - 0.4% of the total weight of the asphalt mixture modifier;

[0010] d. A mineral acid, the amount of which is used to adjust the pH value of the aqueous phase of the asphalt mixture modifier to a range of about 2 to about 4;

[0011] e. A certain amount of water to complete the asphalt mixture modifier.

[0012] In a second aspect, the present invention relates to a modified asphalt paving mixture comprising:

[0013] An asphalt mixture modifier, the amount of which is 1 to 5% of the total weight of the modified asphalt paving mixture, wherein the asphalt contained in the asphalt mixture modifier is the first part of asphalt;

[0014] b. A second part of asphalt having a dynamic viscosity of equal to or greater than 35,000 cP (35 Pa·s) and an API gravity of equal to or greater than 10 degrees, measured at 60°C, wherein the amount of the second part of asphalt is 2 - 8% of the total weight of the modified asphalt paving mixture;

[0015] c. Aggregate, the amount of which is 87% - 97% of the total weight of the modified asphalt paving mixture.

[0016] In a third aspect, the present invention relates to a paved road surface including a layer of the modified asphalt mixture.

[0017] In a fourth aspect, the present invention relates to a method for preparing a modified asphalt mixture, comprising:

[0018] a. Providing a mixture of polyol, surfactant, mineral acid and water, wherein said mixture occurs within a temperature range of 70 to 80 °C;

[0019] b. Providing a mixture of the composition obtained in step a) and a first portion of asphalt, wherein the first portion of asphalt has a dynamic viscosity of equal to or greater than 35,000 cP (35 Pa·s) measured at 60 °C and an API gravity of equal to or greater than 10 degrees, and wherein the first portion of asphalt is within a temperature range of 100 to 150 °C to obtain an asphalt mixture modifier according to any one of claims 1 to 7;

[0020] c. Lowering the temperature of the asphalt mixture modifier obtained in step b) to ambient temperature;

[0021] d. Providing a mixture of a second portion of asphalt, which has a dynamic viscosity of equal to or greater than 35,000 cP (35 Pa·s) measured at 60 °C and an API gravity of equal to or greater than 10 degrees, and wherein the mixture of the second portion of asphalt occurs within a temperature range of 130 to 170 °C;

[0022] e. Providing the asphalt mixture maintained at the ambient temperature obtained in step c) and the mixture in step d), wherein the final mixture is maintained within a temperature range of 130 to 170 °C to obtain the modified asphalt paving mixture;

[0023] f. Subjecting the modified asphalt paving mixture obtained in step e) to controlled cooling until the ambient temperature;

[0024] g. Storing the modified asphalt paving mixture obtained in step f) at the ambient temperature until it is applied to the road surface to be paved.

[0025] In a fifth aspect, the present invention relates to the use of a modified asphalt paving mixture in paving a road surface.

[0026] In a sixth aspect, the present invention relates to a system for preparing an asphalt mixture modifier, comprising:

[0027] a. A mixing tank for providing a mixture of polyol, surfactant, mineral acid and water;

[0028] b. An asphalt tank having a heating device;

[0029] c. A mixing zone for providing a mixture of an aqueous solution comprising the polyol, the surfactant, the mineral acid and water and the asphalt to obtain an asphalt mixture modifier;

[0030] d, at least one heat exchanger to cool the asphalt mixture modifier obtained in step c) to ambient temperature;

[0031] e, at least one storage tank for storing the asphalt mixture modifier.

[0032] The solution to the problem

[0033] Surprisingly, the present invention solves the problems of the prior art by removing the condensed coal part from the asphalt mixture modifier, wherein this component is an essential component of the composition disclosed in WO2014128517, and greatly reduces its viscosity. The emulsifying property of the asphalt mixture modifier of the present invention comprising asphalt, polyol, surfactant and mineral acid is retained, wherein the use of the asphalt mixture modifier in the process of preparing the modified asphalt paving mixture shows that the latter can be stored for a long time, such as from several weeks to six months, without acquiring hardness characteristics. In addition, the asphalt mixture modifier can also improve the stability of the modified asphalt mixture.

[0034] Advantages of the present invention

[0035] The modified asphalt paving mixture of the present invention has high stability in storage and can be properly stored within the ambient temperature, while its functional characteristics can be preserved for a long time, such as from several weeks to six months. In addition, the higher stability of the modified asphalt paving mixture such as the asphalt interlayer of the sidewalk is achieved by adding the asphalt mixture modifier to the modified asphalt paving mixture. Therefore, the modified asphalt paving mixture according to the present invention has several advantages compared with the compositions known in the prior art, because it is no longer necessary to place multiple asphalt preparation units near the area of the road surface to be paved. Instead, according to the present invention, a single preparation unit of the modified asphalt paving mixture can cover a larger ground area, reducing the fixed costs associated with building multiple asphalt preparation facilities. In addition, the operating costs related to the maintenance of the above-mentioned device and the costs related to the transportation of raw materials and final products can also be reduced. In addition, once the modified asphalt paving mixture of the present invention is more stably preserved within the ambient temperature, the batch size can be increased, thereby reducing the costs associated with the preparation itself and making it possible to achieve a more favorable large-scale preparation. Description of the drawings

[0036] To facilitate understanding of the principles consistent with the embodiments of the present invention, reference will be made to the embodiments illustrated in the figures and the language used to describe the same. In any case, it must be understood that no intention is made to limit the scope of the present invention to the content in the figures. Any changes or subsequent variations of the inventive features described herein, as well as any additional applications of the inventive principles and embodiments shown, which would typically occur to those skilled in the art upon reading this description, are considered to be within the scope of the claimed invention.

[0037] Figure 1 An embodiment of the process for obtaining an asphalt mixture modifier and a modified asphalt paving mixture is illustrated.

[0038] Figure 2 An embodiment of the process for obtaining an asphalt mixture modifier is illustrated.

[0039] Figure 3 A schematic diagram of a drop of asphalt mixture modifier is illustrated.

[0040] Figure 4 A schematic diagram of forming particles of a modified asphalt paving mixture is illustrated.

[0041] Figure 5 A Marshall test for calculating the optimum asphalt content in preparing a modified asphalt mixture is illustrated. Detailed Description

[0042] The asphalt mixture modifier of the present invention can be added to a pre-activated asphalt composition within the ambient temperature, and this feature helps to perform the mixing operation more easily because it is not necessary to heat the asphalt mixture modifier to appropriately make the modifier composition fluid. In addition, once the viscosity of the asphalt mixture modifier is significantly reduced, the mixing equipment can be ordinary equipment.

[0043] In a preferred embodiment according to the present invention, the dynamic viscosity of the asphalt mixture modifier measured at 25 °C is in the range of 100 to 300 cP (0.1 Pa·s to 0.3 Pa·s), depending on the amount of asphalt used, and this value is significantly less than the dynamic viscosity of the composition measured at 60 °C disclosed in WO2014128517, about 200000 cP (200 Pa·s). Therefore, the asphalt mixture modifier of the present invention can be processed within the ambient temperature without heat treatment, saving energy and facilitating simpler operations in the preparation process of the modified asphalt paving mixture.

[0044] The composition disclosed in WO2014128517 consists of glycerol, bitumen, and coal, where the latter component is responsible for the higher dynamic viscosity value, which results in the establishment of a combined heating step when this composition is mixed with a pre-activated bitumen composition. Additionally, condensed coal is an environmental pollution material. The pollution of roasted coal is due to its handling in the form of dust, where the pollution stems from the grinding and transportation processes of this material, as the processes disclosed in the prior art require the particles of roasted coal to be approximately 200 microns or smaller.

[0045] Method for preparing an asphalt mixture modifier

[0046] As Figure 1 shown, the method for obtaining an asphalt mixture modifier (9) is by obtaining a mixed aqueous phase including a surfactant (2), a polyol (3), a mineral acid (4), and water (5) within a temperature range of 70 to 80 °C (6) in a first mixing step, and then mixing this mixed aqueous phase with a first portion of bitumen within a temperature range of 100 to 150 °C (1) in a second mixing step. After completing the second mixing step, the resulting composition is subjected to a cooling step to cool to ambient temperature (8), thereby obtaining the asphalt mixture modifier (9). Preferably, in the second mixing step, the first portion of bitumen is introduced within a temperature range of 110 to 150 °C. Preferably, the second mixing step is carried out within a temperature range of 80 to 95 °C.

[0047] Figure 2Describes the process for preparing an asphalt mixture modifier. A surfactant (2), a polyol (3), a mineral acid (4), and water (5) are mixed in a mixing tank (28) which has a dynamic agitator and a pumping system to discharge the resulting aqueous solution. At the same time, a first portion of asphalt (1) is heated in an asphalt tank having a heating device (29), where the heating fluid can be hot oil. By another pumping system, the first portion of asphalt (1) is mixed with the aqueous solution in a second mixing step which may successively include a first static mixer (30), a colloid mill (31), and a second static mixer (30). Regarding the colloid mill (31), two or more colloid mills can be arranged in parallel between them. After completion of the second mixing step, the resulting composition is cooled to ambient temperature by at least one heat exchanger (32) to obtain the asphalt mixture modifier (9) which can be stored in a storage tank (33) and further transported by truck or other suitable vehicle for use in the various stages of preparing a modified asphalt paving mixture (15). The storage tank (33) can have a pump and a recirculation system to recirculate the asphalt mixture modifier when a longer storage time is required. A waste liquid tank (34) can be provided to assist in cleaning the pipes and systems and for batch exchange. The number of devices and their sizes will depend on the production capacity and the optimal storage amount, which can be fully understood by a person skilled in the art.

[0048] In a preferred embodiment according to the present invention, the process for obtaining the mixed aqueous phase includes the following steps: a) providing a quantity of water at 60 °C, where the amount of water is considered in view of the required weight concentration of the remaining components of the asphalt mixture modifier; b) adding the polyol and the cationic and / or nonionic surfactant at the required concentration to the water until they are properly dissolved; c) adjusting the pH value of the solution to be between 2.5 and 3.5; d) in a first mixing step, setting the temperature of the solution in the range of 70 to 80 °C.

[0049] In a more preferred embodiment according to the present invention, during the preparation of the oil phase in the second mixing step, the first portion of asphalt is modified within a temperature range of 110 to 150 °C. Preferably, the process of mixing the two phases (aqueous phase / oil phase) is carried out by at least one colloid mill.

[0050] The first part of the bitumen (1) has a dynamic viscosity, measured at 60 °C, equal to or greater than 35,000 cP (35 Pa·s) and an API gravity equal to or greater than 10 degrees, and its amount accounts for 50 to 75%, preferably 60 to 70%, of the total weight of the bitumen mixture modifier (9). In a preferred embodiment according to the invention, the first part of the bitumen (1) has a dynamic viscosity, measured at 60 °C, between 35,000 cP (35 Pa·s) and 500,000 cP (500 Pa·s). In a preferred embodiment according to the invention, the first part of the bitumen (1) has an API gravity in the range of 10 degrees to 30 degrees.

[0051] As will be understood by those skilled in the art, bitumen can be obtained by the fractional distillation of crude oil and mainly comprises polycyclic aromatic hydrocarbons and has a relatively high viscosity value. The first part of the bitumen helps incorporate the bitumen mixture modifier into the pre-activated bitumen composition.

[0052] The polyol has 2 to 8 carbon atoms and its amount accounts for 2 to 6%, preferably 2 to 4%, of the total weight of the bitumen mixture modifier. Examples of preferred polyols include ethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, pentanediol, glycerol, diglycerol, pentanediol, hexanediol, hexanetriol, 2-ethyl-1,3-hexanediol, 1,2-heptanediol, 1,7-heptanediol, 2,4-heptanediol, 2,5-heptanediol, 1,5-heptanediol, 1,3-heptanediol, 3,4-heptanediol, 1,6-heptanediol, 1,2-octanediol, 1,3-octanediol, 1,4-octanediol, 4,5-octanediol and combinations thereof. Those skilled in the art will fully understand that the stereoisomers of the compounds mentioned herein are also included in the examples of polyols that may be present in the bitumen mixture modifier according to the invention.

[0053] In a preferred embodiment according to the invention, the polyol has a straight chain and contains 3 to 6 carbon atoms. In a more preferred embodiment, the polyol is selected from at least one of propylene glycol, dipropylene glycol, 1,3-butanediol, pentanediol, glycerol, diethylene glycol and combinations thereof. In a more preferred embodiment according to the invention, the polyol is glycerol, which can be substantially pure or used in an aqueous solution, such as a solution containing about 70% by total weight of glycerol.

[0054] Regarding the particles of the modified bitumen paving mixture, as will be detailed below, the polyol has the effect of preventing the formation of lumps between the particles.

[0055] The surfactant (2) comprises a cationic surfactant, a non-ionic surfactant or any combination thereof, and its amount is 0.05 to 0.4%, preferably 0.1 to 0.3%, of the total weight of the bitumen mixture modifier.

[0056] As the cationic surfactant used in the present invention, any cationic surfactant can be used without limitation as long as it can be used to prepare the asphalt mixture modifier according to the present invention.

[0057] Preferred cationic surfactants include alkylamine salt type cationic surfactants, acylamine salt type cationic surfactants, quaternary ammonium salt type cationic surfactants, ammonium salt type cationic surfactants containing amide bonds, ammonium salt type cationic surfactants with ester bonds or ether bonds, imidazoline or imidazolium salt type cationic surfactants. These can be used alone or in combination of two or more.

[0058] Other examples of cationic surfactants can be selected from alkylamide polyamines, alkylimidazoles and alkylimidazole (poly)amines, lignin amines, aliphatic chain alkylamides (poly)amines, aliphatic chain alkyl polyamines, reaction products of fatty carboxylic acids or vegetable oils with polyalkylene polyamines by non-limiting examples. As non-limiting examples, polyalkylene polyamines can be dimethylaminopropylamine, N-aminoethylpiperazine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

[0059] Examples of alkylamine salt type cationic surfactants and acylamine salt type cationic surfactants include primary amine salts (hydrochloride or acetate) having a C 12-18 alkyl group, acylamine salts (hydrochloride, formate, acetate or lactate) having a C 17 alkyl or alkenyl group, N-alkylpolyenepolyamine salts (hydrochloride or acetate, the alkenyl group has 2 to 3 carbon atoms, and the repetition times of the enamine group are 1 to 3) having a C 12-18 alkyl group, fatty acid polyethylamide salts (hydrochloride, the repetition times of the ethyleneamine group are 2) having a C 17 alkyl or alkenyl group, and diethylaminoacetamide salts (hydrochloride, acetate or lactate) having a C 17 alkyl group. These can be used alone or in combination of two or more.

[0060] Examples of quaternary ammonium salt type cationic surfactants and ammonium salt type cationic surfactants containing amide bonds include alkyl or alkenyl trimethylammonium salts (the anion is Cl-, Br-, or CH 12-18 alkyl or C 18 alkenyl group, the anion is Cl-, Br-, or CH 3 SO 4 -), dialkyl or dialkenyl dimethylammonium salts (the anion is Cl-, Br-, or CH 12-18 alkyl or C 18 alkenyl group, the anion is Cl-, Br-, or CH 3 SO 4 -), alkyl or C 12-18 alkyl or C 18Alkyl or alkenyl dimethylbenzyl ammonium salts of alkenyl (anion is Cl-), having C 12-18 Alkyl pyridinium salts of alkyl (anion is Cl-, Br-), having C 17 Alkyl or C 17 Acylaminoethyl ammonium salts of alkenyl (anion is CH 3 SO 4 -), having C 13 Acylaminopropyl dimethylbenzyl ammonium salts of alkyl (anion is Cl-), having C 17 Acylaminopropyl dimethylhydroxyethyl ammonium salts of alkyl (anion is ClO 4 -), having C 11 Acylaminoethyl pyridinium salts of alkyl (anion is Cl-), having C 17 Alkyl or C 17 Diacylaminoethyl dimethyl ammonium salts of alkenyl (anion is Cl-, one of the methyl groups can be hydroxyethyl). Other examples include compounds obtained by cationizing tertiary amines (such as trialkyl or alkenyl) using a quaternizing agent (such as dimethylxylene dichloride). These can be used alone or in combination of two or more.

[0061] Examples of ammonium salt type cationic surfactants containing an ester bond or an ether bond include those having C 17 Alkyl or C 17 Dicyanoethyl hydroxyethyl ammonium salts of alkenyl (anion is CH 3 SO 4 -), and those having C 16 Alkyloxymethyl pyridinium salts of alkyl (anion is Cl-). These can be used alone or in combination of two or more.

[0062] Examples of cationic surfactants of oxazoline or imidazolium salts include those having C 11-17 Alkyl or C 17 Alkyl or alkenyl imidazolines (acetate, carbonate, quaternary ammonium salt) of alkenyl, having C 11-17 1-Hydroxyethyl-2-alkyl or alkenyl imidazolines (including quaternary ammonium salts) of alkyl or C17 alkenyl, and those having C 17 1-Acylaminoethyl-2-alkyl imidazolium salts of alkyl or alkenyl (anion is CH 3 SO 4 -, C 2 H 5 SO 4 -, the alkyl at the second position is methyl or ethyl). These can be used alone or in combination of two or more.

[0063] The above cationic surfactants can be used alone or in combination of two or more.

[0064] Examples of nonionic surfactants include at least one of the following: styrenated phenol polyalkylene oxide adducts, polyalkylene polyamine polyalkylene oxide adducts, polyhydric alcohol fatty acid esters, polyhydric alcohol fatty acid ester polyalkylene oxide adducts, and benzyl phenol polyalkylene oxide adducts, as well as other commonly used nonionic surfactants other than them. These can be used alone or in combination of two or more.

[0065] In a preferred embodiment according to the present invention, examples of nonionic surfactants that can be added to the asphalt mixture modifier are well-known to those skilled in the art and can be selected, by way of non-limiting examples, from polyalkoxylated fatty alcohols, polyalkoxylated nonylphenols or other polyalkoxylated compounds. Alkyl polyglucosides, ethylene oxide / propylene oxide block copolymers with a molar mass Mw of about 4500 g / mol and an ethylene oxide / (ethylene oxide + propylene oxide) weight ratio of about 40%, such as those sold by BASF under the general name Pluronic TM, such as Pluronic TM P94, and the like.

[0066] In embodiments of the present invention that employ cationic and nonionic surfactants, the ratio of the two surfactants depends on the properties of each surfactant. To achieve a proper combination, initially the composition of the asphalt mixture modifier working with the pure surfactants can be determined. Then, the percentage of the surfactant is changed, and the stability performance of the emulsion obtained with each mixture is compared with the percentage of the surfactant mixture for a certain fixed concentration of asphalt.

[0067] In a preferred embodiment, better accommodation of polyols in each micelle will be sought, which may mean using less or more polyols in the aqueous phase, since the way polyols are accommodated in each surfactant is different. Considering the addition of a pure cationic surfactant, a certain proportion of polyols may result in a stable asphalt mixture modifier, but when using a mixture of different surfactants, the same amount of polyols may result in a more stable composition. Therefore, in a more preferred embodiment, the stability of the asphalt mixture modifier may be slightly worse, but it should contain a necessary amount of polyols so that the modified asphalt paving mixture does not harden.

[0068] In a preferred embodiment according to the present invention, regarding the amount of surfactant present in the asphalt mixture modifier, the cationic surfactant accounts for 92% to 96% of the total weight of the surfactant, and the nonionic surfactant accounts for 4% to 8% of the total weight of the surfactant.

[0069] The role of the surfactant is to affect the surface forces of the particles of the modified asphalt paving mixture and promote the proximity between the particles.

[0070] When the surfactant is cationic, the droplets of the asphalt mixture modifier do not attract each other because the repulsive force between them is caused by the same charge on the surface of the surfactant layer. On the other hand, when the surfactant is non-ionic, the droplets of the asphalt mixture modifier do not attract each other due to the steric force. Therefore, this set of repulsive forces is beneficial to improving the stability of the asphalt mixture modifier.

[0071] The amount of mineral acid is used to adjust the pH value of the aqueous phase in the asphalt mixture modifier within the range of about 2 to about 4, preferably 2.5 to 3.5.

[0072] Examples of mineral acids include at least one of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. These can be used alone or in combination of two or more. In a preferred embodiment according to the present invention, the mineral acid used is hydrochloric acid.

[0073] Those skilled in the art will fully understand that the amount of water is used to complete emulsification because this component is the continuous phase of emulsification.

[0074] Method for preparing a modified asphalt paving mixture

[0075] As Figure 1 shown, the method for obtaining a modified asphalt paving mixture (17) includes the step of obtaining a pre-activated asphalt composition (12) by mixing aggregate (10) with a second portion of asphalt (11), wherein this step is carried out by a known method of the prior art to obtain a pre-activated asphalt composition (13), wherein this mixing preferably occurs within 130 °C to 170 °C. Preferably, the aggregate (10) and the second portion of asphalt (11) can be preheated to 130 °C to 170 °C respectively.

[0076] As Figure 1 shown, by providing a mixture of an asphalt mixture modifier (9) maintained within ambient temperature in a preferred embodiment and a heated pre-activated asphalt composition (13), the heated pre-activated asphalt composition (13) is subjected to the step of obtaining a modified asphalt mixture (14) within 130 °C to 170 °C, wherein the final mixture is maintained within 130 °C to 170 °C, thereby obtaining a modified asphalt paving mixture. Preferably, when within 130 to 170 °C, the asphalt mixture modifier (9) is added to the pre-activated asphalt composition (13) in a mixing drum, thereby obtaining a modified asphalt paving mixture. More preferably, this step is carried out a few seconds after the second portion of asphalt enters the mixing drum and it has been adaptively applied to the aggregate.

[0077] The second part of the asphalt has a dynamic viscosity equal to or greater than 35,000 cP (35 Pa·s) measured at 60 °C and an API gravity equal to or greater than 10 degrees. In the modified asphalt paving mixture, one function of the asphalt is to act as a binder to hold the asphalt together. The amount of the second part of the asphalt is 2 - 8% of the total weight of the modified asphalt paving mixture. In a preferred embodiment according to the present invention, the amount of the second part of the asphalt is 3.5 - 6.5% of the total weight of the modified asphalt paving mixture. In a preferred embodiment according to the present invention, the second part of the asphalt (1) has a dynamic viscosity measured at 60 °C between 35,000 cP (35 Pa·s) and 500,000 cP (500 Pa·s). In a preferred embodiment according to the present invention, the second part of the asphalt (1) has an API gravity between 10 and 30 degrees.

[0078] In a more preferred embodiment according to the present invention, the sum of the first asphalt part included in the asphalt mixture modifier and the second asphalt part included in the pre-activated asphalt composition must be consistent with the amount of asphalt required as the optimal amount of the asphalt mixture designed for a specific job.

[0079] In a more preferred embodiment according to the present invention, the two asphalt parts should have the same specifications and have similar hardness characteristics. In some applications, different types of asphalt can be used, where the hardness difference between each of them is not significant.

[0080] The aggregates used to prepare the modified asphalt paving mixture can be crushed stone, sand, gravel or slag, and combinations thereof.

[0081] In a preferred embodiment according to the present invention, the aggregates include components selected from dense-graded aggregates, gap-graded aggregates, open-graded aggregates, stony aggregates, recycled asphalt paving materials, and combinations thereof.

[0082] The aggregates contribute to demonstrating the stability of the paving composition after being applied to the road surface to be paved. The amount of the aggregates is 87% to 97% of the total weight of the modified asphalt paving mixture. In a preferred embodiment according to the present invention, the amount of the aggregates is 93% to 96% of the total weight of the modified asphalt paving mixture.

[0083] The amount of the asphalt mixture modifier is 1 - 5% of the total weight of the modified asphalt paving mixture. In a preferred embodiment according to the present invention, the amount of the asphalt mixture modifier is 1.5 - 3.5% of the total weight of the modified asphalt paving mixture.

[0084] The modified asphalt paving mixture (17) can be directly used on the road surface to be paved while its temperature is still within the application range, for example, from 130 °C to 170 °C.

[0085] Surprisingly, after cooling by the step of controllably cooling the modified asphalt paving mixture to the ambient temperature (15), the modified asphalt paving mixture (17) can be submitted to the step of storing the modified asphalt paving mixture at the ambient temperature (16) until it is applied to the road surface to be paved. Herein, the storage can last, for example, from several weeks to several months, without reducing the stability of the modified asphalt paving mixture, and the modified asphalt paving mixture is stored, for example, within the ambient temperature range. In experiments, good results have been obtained during indoor storage for up to 6 months.

[0086] In a preferred embodiment according to the present invention, in the step of controllably cooling the modified asphalt paving mixture to the ambient temperature (15), the controllable cooling of the modified asphalt paving mixture includes cooling the modified asphalt paving mixture at a cooling rate proportional to the preparation rate of the modified asphalt paving mixture. In a more preferred embodiment, the cooling rate of the modified asphalt paving mixture is substantially the same as the preparation rate of the modified asphalt paving mixture.

[0087] After a certain storage period, before being applied to the road surface to be paved, the modified asphalt paving mixture (17) is heated to a temperature range of 130 °C to 170 °C. Herein, surprisingly, the modified asphalt paving mixture retains all the necessary characteristics for being properly applied to the road surface to be paved.

[0088] Without wishing to be bound by any theory, Figure 3 A schematic diagram of the asphalt mixture modifier (9) is shown, wherein a core composed of droplets of a first portion of asphalt in the asphalt mixture modifier (19) is surrounded by a surfactant and a polyol inner layer in an acidic aqueous medium in the asphalt mixture modifier (20) particles. This inner layer promotes cometing, i.e., the formation of mixed micelles, wherein the polyol, in addition to having the function of preventing the modified asphalt mixture from hardening, also has the function of acting as a co-surfactant. In this figure, the asphalt-soluble tails of the surfactant molecules extend into the asphalt core, while the water-soluble ends remain in contact with the aqueous medium. In addition, the inner layer of the surfactant and the polyol in the acidic aqueous medium is surrounded by an outer layer of the polyol in the acidic aqueous medium, which is the particle (21) of the asphalt mixture modifier.

[0089] Without wishing to be bound by any theory, the applicant is in Figure 4A schematic diagram related to the formation of a modified asphalt paving mixture (17) is presented. When a hot pre-activated asphalt composition (13), which includes an aggregate core (22) surrounded by a second portion of asphalt covering the aggregate from the hot pre-activated asphalt composition (23), is mixed with an asphalt mixture modifier (9) within the range of 130 °C to 170 °C, substantially all of the water in the surfactant and polyol layer in the acidic aqueous medium contained in the particles of the asphalt mixture modifier (20) evaporates. The evaporation of the water causes the asphalt mixture modifier (9) to suddenly break down on the second portion of the asphalt layer that covers the aggregate from the hot pre-activated asphalt composition (23), thereby producing particles of a modified asphalt paving mixture (17).

[0090] During the collapse of the asphalt mixture modifier, since the boiling point of the polyol is relatively high and it is not evaporated, the material including the first portion of asphalt, surfactant, and polyol is laid on the outer surface of the second portion of the asphalt layer that covers the aggregate from the hot pre-activated asphalt composition (23), forming a thicker final layer of asphalt that covers the aggregate in the modified asphalt paving mixture (25), and this modified asphalt paving mixture (25) covers the aggregate core of the modified asphalt paving mixture (24). The thicker final layer of asphalt covering the aggregate in the modified asphalt paving mixture (25) is composed of materials from the first portion of asphalt (1) and the second portion of asphalt (11).

[0091] The size of the asphalt spheres within the asphalt mixture modifier (9) is small, with the average size of the asphalt spheres being on the order of 8 to 12 micrometers, and some are larger and some are smaller depending on the formulation and shear conditions of the colloid mill. Additionally, the viscosity of the asphalt mixture modifier, measured at 25 °C, is within the range of 100 to 300 cP (0.1 Pa·s to 0.3 Pa·s). When the asphalt mixture modifier is added to the pre-activated asphalt composition (13), the first portion of asphalt provides a much larger coverage area compared to the coverage rate provided by the asphalt in a conventional hot asphalt mixture, because according to the present invention, the asphalt used in the asphalt mixture modifier has a higher viscosity of equal to or greater than 35,000 cP (35 Pa·s) measured at 60 °C. Therefore, the amount of voids generated by the asphalt mixture modifier in the modified asphalt paving mixture is reduced, and thus, it provides better stability.

[0092] In addition, a schematic diagram of the particles of the modified asphalt paving mixture (17) presents an intermediate final layer of surfactant and polyol in the modified asphalt paving mixture (26) and an outer final layer of polyol in the modified asphalt paving mixture (27), wherein once the polyol is insoluble in the asphalt fraction, the outer layer of the polyol prevents the particles of the modified asphalt paving mixture from forming lumps or agglomerates.

[0093] In a preferred embodiment according to the present invention, the total amount of asphalt, including the sum of the first part of asphalt (1) and the second part of asphalt (11), is a relevant parameter to meet an appropriate long storage period and appropriate adhesion between the particles of the modified asphalt paving mixture. When the total amount of asphalt exceeds the optimal range, irreversible hardening of the modified asphalt mixture may occur during storage. In a preferred embodiment, the total amount of asphalt is 3% to 8% of the total weight of the modified asphalt paving mixture. In a more preferred embodiment, the total amount of asphalt is 3.5% to 6.5% of the total weight of the modified asphalt paving mixture.

[0094] Examples

[0095] To determine the desired value of the total amount of asphalt in the modified asphalt paving mixture, the Marshall method (Manual Series N.02 (MS-2) Asphalt Mixture Design Method. Seventh Edition 2014 Asphalt Institute) was used. This method is suitable for determining the important properties of asphalt components and evaluating and predicting failures due to traction. The amount of asphalt used and the particle size of the aggregate can be selected, for example, according to the number and size of the required vehicles, such as light, medium or heavy vehicles. The asphalt-coated aggregate samples may include 3% to 8% of asphalt, i.e., 4.5%, 5.0%, 5.5% and 6.0% of asphalt.

[0096] As Figure 5As shown, the Marshall method evaluates the stability of asphalt-coated aggregates after performing a stability test under dry conditions and another test under wet conditions, where the latter is equivalent to evaluating whether the amount of asphalt can provide ideal stability when the asphalt-coated aggregates are immersed in water for a period of time. As shown in Table 1, the Marshall method sets a maximum acceptable value for loss of stability for certain service conditions of the paving, such as a paved road. The Marshall method uses compacts with a diameter of 10 cm and a height of 6.25 cm or a diameter of 15 cm and a height of 9.375 cm. Considering the optimum amount of asphalt in the modified asphalt paving mixture, for example, 5.7% by weight of the total composition, 4.7% of the necessary asphalt can be used in the step of obtaining the pre-activated asphalt composition (13), and the remaining amount is reserved for use in the step of obtaining the asphalt mixture modifier (9). Those skilled in the art will fully understand that various combinations can be employed to achieve an appropriate and optimal quality balance when considering the quantities related to the first part of asphalt (1) and the second part of asphalt (11), thereby obtaining the optimal total amount of asphalt.

[0097]

[0098]

[0099] In addition, the stability characteristics of the modified asphalt paving mixture after adding the asphalt mixture modifier are improved, as shown in Table 2, which lists the stability results of two samples of the modified asphalt paving mixture according to the present invention, submitted to the standard of the Marshall method for heavy traffic.

[0100]

[0101] Another advantage of the modified asphalt mixture according to the present invention compared to the prior art is that when different batches of the mixture are heated near the construction site, granulation and thermal standardization can be better achieved.

[0102] In another aspect, the present invention refers to a paved road surface including at least one layer of modified asphalt paving mixture. The road surface to be paved includes roads, parking lots, railway tracks, ports, airport runways, bicycle lanes, sidewalks, and game and sports areas.

[0103] As used herein, the term "ambient temperature" refers to an ambient temperature below about 40°C, i.e., from 10°C to 45°C.

[0104] As used in this specification, the expressions "about" and "close to" refer to a numerical range of about 10% of the specified number.

[0105] As used in this specification, the term "substantially" means that the actual value is within an interval of about 10% of the expected value, variable, or related limitation, particularly within about 5% of the expected value, variable, or related limitation, or particularly within about 1% of the expected value, variable, or related limitation.

[0106] The subject matter described above is provided as an illustration of the present invention and should not be construed as a limitation thereof. According to the present invention, the terms used to describe specific embodiments should not be construed as limiting the present invention. The singular forms of the definite and indefinite articles used in this specification are intended to include the plural forms in the interpretation, unless the context of the description clearly indicates the contrary. It should be understood that when the expressions "comprising" and "including" are used in this specification, the presence of the specific features, elements, components, steps, and related operations is specified, but the possibility that other features, elements, components, steps, and operations are also taken into consideration is not excluded.

[0107] All modifications, as long as they do not modify the basic features of the following claims, must be considered to be within the scope of protection of the present invention.

[0108] Industrial Applicability

[0109] The present invention relates to an asphalt mixture modifier, which is used as an additive in a modified asphalt paving mixture for paving roads.

[0110] List of Reference Numerals

[0111] 1. First portion of asphalt within the temperature range of 100 °C to 150 °C

[0112] 2. Surfactant

[0113] 3. Polyol

[0114] 4. Mineral acid

[0115] 5. Water

[0116] 6. First mixing step at 70 °C to 80 °C

[0117] 7. Second mixing step at 70 °C to 98 °C

[0118] 8. Step of cooling to ambient temperature

[0119] 9. Asphalt mixture modifier

[0120] 10. Aggregate within the temperature range of 130 °C to 170 °C

[0121] 11. Second portion of asphalt within the temperature range of 130 °C to 170 °C

[0122] 12. Steps for obtaining a pre-activated asphalt composition 13. Pre-activated asphalt composition

[0123] 14. Steps for obtaining a modified asphalt paving mixture within the range of 130°C to 170°C 15. Controlling the cooling of the modified asphalt mixture until the ambient temperature 16. Steps for storing the modified asphalt mixture at the ambient temperature 17. Modified asphalt mixture

[0124] 18. Steps for applying the modified asphalt mixture to the road surface to be paved 19. A first portion of asphalt in an asphalt mixture modifier 20. A surfactant and polyol layer in an acidic aqueous medium in asphalt mixture modifier particles 21. A polyol layer in an acidic aqueous medium in asphalt mixture modifier particles 22. Aggregates in the pre-activated asphalt composition

[0125] 23. A second asphalt layer covering the aggregates in the hot pre-activated asphalt composition 24. Aggregates in the modified asphalt mixture

[0126] 25. A thicker final asphalt layer covering the aggregates in the modified asphalt mixture 26. The final layer of surfactant and polyol in the modified asphalt mixture 27. The final layer of polyol in the modified asphalt mixture

[0127] 28. Mixing tank

[0128] 29. Asphalt tank with a heating device

[0129] 30. Static mixer

[0130] 31. Colloid mill

[0131] 32. Heat exchanger

[0132] 33. Storage tank

[0133] 34. Waste tank

[0134] 35. Paved road surface

[0135] Citation list

[0136] The citation list is as follows:

[0137] Patent document

[0138] PTL1: International Patent Application WO2014128517A1

Claims

1. An asphalt mixture modifier, characterized in that, it comprises: a. Asphalt having a dynamic viscosity of equal to or greater than 35,000 cP (35 Pa·s) and an API gravity of equal to or greater than 10 degrees measured at 60 °C, wherein the amount of the asphalt is 50 - 75% of the total weight of the asphalt mixture modifier; b. A polyol having 2 - 8 carbon atoms, the amount of which is 2 - 6% of the total weight of the asphalt mixture modifier; c. A surfactant, wherein the surfactant includes a cationic surfactant, a nonionic surfactant or any combination thereof, and the amount of the surfactant is 0.05 - 0.4% of the total weight of the asphalt mixture modifier; d. A mineral acid, the amount of which is used to adjust the pH value of the aqueous phase of the asphalt mixture modifier to the range of 2 to 4; e. A certain amount of water to complete the asphalt mixture modifier.

2. The asphalt mixture modifier according to claim 1, characterized in that, the amount of the asphalt is 60 - 70% of the total weight of the asphalt mixture modifier.

3. The asphalt mixture modifier according to claim 1 or 2, characterized in that, the amount of the polyol is 2 - 4% of the total weight of the asphalt mixture modifier.

4. The asphalt mixture modifier according to claim 1, characterized in that, the polyol has a straight chain and 3 to 6 carbon atoms.

5. The asphalt mixture modifier according to claim 1, characterized in that, the polyol is selected from at least one of propylene glycol, dipropylene glycol, 1,3 - butanediol, pentanediol, glycerol, diglycerol and their combinations.

6. The asphalt mixture modifier according to claim 1, characterized in that, the amount of the surfactant is 0.1 - 0.3% of the total weight of the asphalt mixture modifier.

7. The asphalt mixture modifier according to claim 1, characterized in that, the mineral acid is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid and their combinations.

8. A modified asphalt paving mixture, characterized in that, it comprises: a. The asphalt mixture modifier according to any one of claims 1 to 7, the amount of which is 1 - 5% of the total weight of the modified asphalt paving mixture, wherein the asphalt contained in the asphalt mixture modifier is the first part of asphalt; b. The second part of asphalt having a dynamic viscosity of equal to or greater than 35,000 cP (35 Pa·s) and an API gravity of equal to or greater than 10 degrees measured at 60 °C, wherein the amount of the second part of asphalt is 2 - 8% of the total weight of the modified asphalt paving mixture; c. Aggregate, the amount of which is 87% - 97% of the total weight of the modified asphalt paving mixture.

9. The modified asphalt paving mixture according to claim 8, characterized in that, the amount of the asphalt mixture modifier is 1.5 - 3.5% of the total weight of the modified asphalt paving mixture.

10. The modified asphalt paving mixture according to any one of claims 8 or 9, characterized in that, The amount of the second part of asphalt is 3.5 - 6.5% of the total weight of the modified asphalt paving mixture.

11. The modified asphalt paving mixture according to claim 8, wherein, the amount of the aggregate is 93% - 96% of the total weight of the modified asphalt paving mixture.

12. The modified asphalt paving mixture according to claim 8, wherein, the aggregate includes components selected from dense - graded aggregate, gap - graded aggregate, open - graded aggregate, stone aggregate, recycled asphalt paving material, and combinations thereof.

13. A paved road surface, wherein, it includes a layer of the modified asphalt paving mixture according to any one of claims 8 to 12.

14. A method for preparing the modified asphalt paving mixture according to any one of claims 8 to 12, wherein, it includes: a. Providing a mixture of polyol, surfactant, mineral acid, and water, wherein the mixture occurs within a temperature range of 70 to 80 °C; b. Providing a mixture of the composition obtained in step a) and the first part of asphalt, the first part of asphalt having a dynamic viscosity equal to or greater than 35,000 cP (35 Pa·s) measured at 60 °C and an API gravity equal to or greater than 10 degrees, wherein the first part of asphalt is within a temperature range of 100 to 150 °C to obtain the asphalt mixture modifier according to any one of claims 1 to 7; c. Reducing the temperature of the asphalt mixture modifier obtained in step b) to ambient temperature; d. Providing aggregate, providing the second part of asphalt, which has a dynamic viscosity equal to or greater than 35,000 cP (35 Pa·s) and an API gravity equal to or greater than 10 degrees measured at 60 °C; mixing the second part of asphalt with the aggregate, wherein the mixing of the second part of asphalt occurs within a temperature range of 130 °C to 170 °C; e. Providing the asphalt mixture modifier maintained at the ambient temperature obtained in step c) and the mixture in step d), wherein the final mixture is maintained within a temperature range of 130 °C to 170 °C to obtain the modified asphalt paving mixture; f. Conducting controlled cooling of the modified asphalt paving mixture obtained in step e) until the ambient temperature; g. Storing the modified asphalt paving mixture obtained in step f) at the ambient temperature until it is applied to the road surface to be paved.

15. The method for preparing a modified asphalt paving mixture according to claim 14, wherein, before being applied to the road surface to be paved, the modified asphalt paving mixture is heated to a compaction temperature range of 130 °C to 170 °C.

16. The method for preparing a modified asphalt paving mixture according to any one of claims 14 or 15, wherein, the controlled cooling of the modified asphalt paving mixture in step f) includes cooling the modified asphalt paving mixture at a cooling rate proportional to the preparation rate of the modified asphalt paving mixture.

17. A use of the modified asphalt paving mixture according to any one of claims 8 to 12, wherein, Applied to paving roads.

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