KR100789572B1 - Asphalt Composition Containing Modified Sulfur Binder and Asphalt Concrete Using the Same - Google Patents

Abstract

The present invention is excellent in the storage stability in the liquid phase, but in the process of converting it from the liquid phase to the solid phase, an inefficient element such as supercooling is suppressed as much as possible, the asphalt composition containing a modified sulfur binder having improved usability, asphalt concrete using the asphalt composition In the present invention, while exhibiting excellent workability in producing asphalt concrete, it can exhibit improved mechanical strength characteristics compared to conventional general asphalt concrete.

Modified sulfur binder, asphalt concrete, fine aggregate, coarse aggregate, Marshall stability

Description

Asphalt Composition Containing Modified Sulfur Binder and Asphalt Concrete Using the Same}

1 is a view showing the relationship between the amount of general asphalt used in conventional asphalt concrete and the amount of asphalt composition (modified sulfur binder + general asphalt) according to the present invention according to a preferred embodiment of the present invention.

2 is a view schematically showing a process for producing asphalt concrete according to a wet method in one embodiment of the present invention.

3 is a view schematically showing a process for producing asphalt concrete according to a dry method in another embodiment of the present invention.

Figure 4 shows the results of measuring the hardness (Shore D) over time during the cooling of the pure sulfur melted at 140 ℃ in Example 2, and each of the molten samples 1, 3 and 5 of Example 1 Drawing,

5A and 5B are electron micrographs of the crystal structure observed after solidifying Samples 1 and 3 in Example 2, respectively, and

6 is a view showing the degree to which the viscosity of the liquid samples 2 to 5 prepared in Example 3 of the present invention changes with time during the storage process at 130 ° C.

7a and 7b is a view showing a process for producing an asphalt concrete containing a modified sulfur binder according to the wet method and dry method according to Example 5 of the present invention,

FIG. 8 is a diagram showing wheel tracking test results between general asphalt concrete and asphalt concrete containing the modified sulfur binder according to the sixth embodiment of the present invention.

FIG. 9 is a photograph of a wheel tracking specimen showing wheel tracking test results between general asphalt concrete and asphalt concrete containing the modified sulfur binder according to the sixth embodiment of the present invention.

10 is a view showing the indirect tensile strength test results between the asphalt concrete containing the modified sulfur binder of the present invention and the general asphalt concrete according to Example 7 of the present invention.

The present invention relates to an asphalt composition containing a modified emulsion binder and concrete using the same. More specifically, the present invention provides an asphalt composition containing a modified sulfur binder having excellent storage stability and improved usefulness while being excellent in terms of storage stability in a liquid phase but suppressing inefficient elements such as supercooling in the process of converting the same from a liquid phase to a solid phase. The present invention relates to an asphalt concrete having excellent workability and mechanical properties and a method of manufacturing the same.

In general, asphalt is black at room temperature and is widely known in the art as a highly viscous material of a sticky semi-solid state. Such asphalt is typically used primarily as a material for heated asphalt concrete or hot mix asphalt (HMA), which is used in asphalt paving. That is, asphalt concrete basically means a mixture form of asphalt and aggregate. When the asphalt is heated, it is easily liquefied and mixed well with the aggregate, and because it is sticky itself, it adheres well with the aggregate to form HMA.

As described above, the asphalt is classified into natural asphalt and petroleum asphalt in the commercial aspect. Natural asphalt is a natural product of crude oil, a mixture of hydrocarbons soluble in CS ₂ and a bituminous substance that is solid or semisolid at room temperature. Petroleum-based asphalt is produced during refining of crude oil, and has a structure in which hydrocarbons are dispersed in petroleum in colloidal form. Since the refinery of crude oil was invented in the early 1900s, with the rapid development of the oil industry along with the automobile industry, high-quality petroleum-based asphalt began to be produced in large quantities, and natural asphalt became less important. .

However, since asphalt concrete mixed with aggregate using only asphalt cannot meet the increasing demand for physical properties, various reforming components have been proposed to improve this.

A notable technique of these options is the use of sulfur as a reforming component. In fact, sulfur is a component that is obtained in large quantities as a result of the desulfurization process that is essentially performed in the crude oil refining process, and its utilization method has been continuously required. Such sulfur components have conventionally been widely used as binders in the manufacture of mortar or concrete, and have also been used alone or in combination with other components (eg, rubber components, polymers, etc.) in asphalt concrete production. The related art in this regard is as follows.

U.S. Patent No. 3,738,853 discloses the use of sulfur-asphalt-aggregates in which the mixing ratio of sulfur to asphalt (by weight) is at least 1: 1. U.S. Pat. No. 4,756,763 also discloses that first, sulfur is mixed with molten asphalt to form a uniform mixture, and then formed into a solid pellet form (weight ratio of pellets to asphalt is at least 2.3 or more). Disclosed is a method for producing asphalt concrete by transferring to a site and mixing with aggregate under heating.

U.S. Pat.No. 5,672,645 discloses a method for use in road applications by mixing sulfur and asphalt and then uniformly mixing it with polymers (e.g. urethanes, polyesters, thermoplastic elastomers, etc.) to produce usable polymer-asphalt blends. The technique is disclosed. Meanwhile, US Patent No. 6,180,697 discloses an asphalt-polymer composition by heating asphalt so as to be stirred, and then sequentially adding and stirring a thermoplastic elastomer and a crosslinking composition (comprising 2-mercaptobenzothiazole and sulfur). Disclosed is a manufacturing method, wherein the asphalt-polymer composition may be mixed with aggregate and applied to road pavement and the like.

In addition, US Pat. No. 6,743,839 discloses (A) 1-10% by weight of modified asphalt cement consisting of 90-99% by weight of asphalt and 1-10% by weight of polydiene rubber having a repeating unit derived from conjugated diene monomer and sulfur. ; And (B) asphalt concrete comprising 90 to 99% by weight of aggregate. In addition, Japanese Patent Laid-Open No. 13-348485 discloses a rubber-modified asphalt added with sulfur.

The above-mentioned prior art can be seen as a technique in which pure sulfur is used in asphalt concrete, or a rubber-based component or a polymer is mainly used as a main reforming component, but additionally sulfur or a rubber or a polymer is modified with sulfur.

However, in the case of using pure sulfur, many problems are caused in mechanical properties. In order to solve the problems caused when using pure sulfur as a binder, a method of using a specific compound for addition as a modifier has been studied. In particular, as such a compound for addition, dicyclopentadiene is known to have a low price and excellent economical efficiency, and to have a good effect on the development of mechanical strength (New Uses of Sulfur-II, pp. 68 to 77 ( 1978).

In this regard, Japanese Patent Application Laid-Open No. 2-28529 and its corresponding US Pat. No. 4,391,969 disclose polymers reacted with a modifier containing sulfur and from 2 to 20% by weight of a cyclopentadiene oligomer mixture-dicyclopentadiene. It discloses a modified sulfur binder consisting of, wherein the content of the cyclopentadiene oligomer in the modifier is required to be at least 37%. According to the patent, it is briefly mentioned that such a modified sulfur binder can be applied for asphalt use, but mainly describes the application to mortar or concrete. According to the patent, a process of heating the composition of sulfur and a modifier is followed by curing, wherein such cyclopentadiene oligomers, such as trimers, tetramers and pentamers of cyclopentadiene, It means oligomers other than dicyclopentadiene. In particular, there is a feature in that not only dicyclopentadiene but also a trimer or more oligomer of cyclopentadiene is added in a predetermined amount or more as a modifier.

As described above, the binder in which sulfur is modified with a cyclopentadiene-based modifier has conventionally been mainly applied to mortar or concrete. In addition, in the application thereof, a binder, which is a reaction product of a modified component such as sulfur and dicyclopentadiene, is separately prepared in a solid phase, and then, when the aggregate is used for construction or civil engineering materials such as concrete, A method of mixing and cooling at a specific ratio or by melting and mixing sulfur, modified components and aggregates in one step under specific process conditions is employed. However, the process of cooling the hot molten binder to a solid phase has been pointed out as a problem in terms of productivity and energy efficiency, and facility investment for solidification is also acting as a factor in manufacturing cost. This is a phenomenon that is also a problem in the production of asphalt concrete.

In addition, in the cooling step for actual solidification, the reaction product tends to exist in a supercooled state, that is, in a slime state, rather than in a solid state, even though it is a room temperature condition. Therefore, since the supercooled state requires a considerable time until the solidification is eliminated, there is a serious disadvantage in terms of time and economics. In particular, as the content of the modifying component increases, the polymerization reaction increases, such a supercooling phenomenon becomes worse.

In this regard, in the case of the prior art, not only does not specifically mention the composition, process conditions, etc. for manufacturing a binder suitable for the liquid form, but also a technical problem that is not considered in manufacturing a conventional solid form binder needs to be solved. have. In particular, it should be able to be stored above a certain temperature prior to mixing with the aggregate, and the way to suppress the change of physical properties as much as possible during this storage period should be considered. In addition, it is often required to store and transport the liquid reformed sulfur binder as a solid phase even in view of the above-described problems in the solid reformed sulfur binder. The liquid reformed sulfur binder is supercooled during the cooling process for solidification. It is also an important consideration to ensure that the same phenomenon can be suppressed as much as possible.

In view of the above, the present applicant exhibits mechanical properties equivalent to those of the conventionally known binders and solid-state modified sulfur binders in Korean Patent Application No. 2005-23423, and the change of physical properties such as viscosity in the liquid storage process can be suppressed as much as possible. In some cases, a modified sulfur binder and a method for producing the same are disclosed, in which a supercooling phenomenon is effectively suppressed when converted to a solid phase. In addition, the applicant's Korean Patent Application No. 2005-34898 discloses mortar and concrete using the modified sulfur binder disclosed in the patent.

However, it is necessary to more specifically identify the conditions such as the mixing ratio with various aggregates in order that the above-described binder material exhibits its advantages even in asphalt to the maximum and satisfies various mechanical and chemical properties required for asphalt concrete.

In order to overcome the shortcomings of the prior art using conventional asphalt concrete and sulfur components known in the prior art as the main binder components, the present inventors have made excellent mechanical and chemical based on the modified sulfur binder disclosed in Korean Patent Application No. 2005-23423. It is to develop a modified sulfur asphalt having physical properties and asphalt concrete prepared therefrom.

Accordingly, an object of the present invention is to show the mechanical properties equivalent to those of the conventional solid-state modified sulfur binder in the liquid phase, while the change in physical properties such as viscosity in the liquid phase holding process can be suppressed as much as possible, and cooling is particularly required when solidification is required. It is to provide an asphalt composition and a asphalt concrete containing the modified sulfur binder that can be stored and transported to minimize the supercooling phenomenon during the process.

Another object of the present invention is to provide a method for effectively producing asphalt concrete using the asphalt composition.

In order to achieve the above object, according to the first aspect of the present invention, melting of 96 to 98% by weight of sulfur and 2 to 4% by weight of a dicyclopentadiene-based modifier substantially free of oligomers of at least trimers of cyclopentadiene Asphalt comprising a reaction product under the conditions, comprising a modified sulfur binder and asphalt in which the tetragonal crystal content of sulfur is in the range of 40 to 80% by weight in the reaction product in a weight ratio of 2: 8-5: 5. A composition is provided.

According to a second aspect of the invention, it comprises (A) 2 to 10% by weight asphalt composition and (B) 90 to 98% by weight aggregate,

The asphalt composition comprises (i) a reaction product under melting conditions of 96 to 98% by weight sulfur and 2 to 4% by weight of a dicyclopentadiene-based modifier that is substantially free of oligomers of at least trimers of cyclopentadiene. A modified sulfur binder having a tetragonal crystal content of sulfur in the reaction product in the range of 40 to 80% by weight, and (ii) asphalt concrete, characterized in that the asphalt consists of a weight ratio of 2: 8-5: 5.

According to a third aspect of the invention,

a) melt-mixing the modified sulfur binder and asphalt at a weight ratio of 2: 8-5: 5 under heat-mixing conditions to prepare an asphalt composition; And

b) mixing 90 to 98 wt% of the aggregate with 2 to 10 wt% of the asphalt composition under heat mixing conditions;

Wherein the asphalt composition comprises (i) a reaction product under melting conditions of 96 to 98% by weight of sulfur and 2 to 4% by weight of a dicyclopentadiene-based modifier that is substantially free of oligomers of at least trimers of cyclopentadiene. Including the modified sulfur binder in the reaction product in the tetragonal crystal content of sulfur in the range of 40 to 80% by weight and (ii) Asphalt production of asphalt concrete, characterized in that consisting of a weight ratio of 2: 8-5: 5. A method is provided.

According to a fourth aspect of the present invention, the method includes mixing asphalt, modified sulfur binder and aggregate under heat mixing conditions,

The reformed sulfur binder comprises a reaction product under melting conditions of 96 to 98% by weight sulfur and 2 to 4% by weight of a dicyclopentadiene-based modifier substantially free of oligomers of at least trimers of cyclopentadiene. The tetragonal crystal content of sulfur in the product ranges from 40 to 80% by weight,

The weight ratio of the asphalt and the modified sulfur binder is 2: 8 to 5: 5, and

Asphalt composition consisting of the asphalt and the modified sulfur binder in the mixture, and the method for producing asphalt concrete, characterized in that the content of the aggregate is 2 to 10% by weight and 90 to 98% by weight, respectively.

Hereinafter, the present invention can be achieved by the following description with reference to the accompanying drawings.

In the present invention, the "storage stability in the liquid phase" is described based on the viscosity, which is one of the most important physical properties of the produced reformed sulfur binder in the liquid phase, specifically, the maximum viscosity characteristics in the storage temperature range of the produced reformed sulfur binder This means that it can be kept stable. In addition, in the present invention, the expression “substantially free of oligomers of at least trimers of cyclopentadiene” indicates that at most 0.5 wt%, preferably at most 0.2, of oligomers of at least trimers of cyclopentadiene as impurities in the modifier. It can be contained by weight percent.

On the other hand, in the present invention, asphalt concrete (asphalt concrete) is commonly known as asphalt, in addition to asphalt, asphalt mixture, HMA (hot mix asphalt) and the like. In general, asphalt concrete refers to heat-mixing asphalt (asphalt) and aggregates (coarse aggregates and / or fine aggregates), and in some cases, additional packing fillers (eg, mineral fillers such as stone powder) may be added. It is applied to road pavement or parking lot. In addition, it is variously classified according to the purpose of use, use, function, construction method, and the like.

Reformed Sulfur Binder

As described above, the modified sulfur binder used in the present invention is disclosed in Korean Patent Application No. 2005-23423, which is included as a reference of the present invention. The explanation is as follows:

The reformed sulfur binder provided in accordance with the present invention is a reaction of sulfur with a small amount of modifier under melting conditions, and as a result of the reaction, polysulfide is produced to give a physical property improving effect according to the reforming. In this regard, more specific reaction mechanisms are described in US Pat. No. 4,311,826, which is also incorporated by reference in the present invention.

According to the present invention, sulfur which can be used for the production of reformed sulfur binders may use conventional sulfur elements, and in particular, sulfur derived from the refining process of crude oil or natural sulfur derived from mines.

Modifiers used for sulfur reforming are dicyclopentadiene-based modifiers. Such modifiers include dicyclopentadiene (DCP) as a modifier and include cyclopentadiene (CP) and / or derivatives thereof (e.g., methylcyclopentadiene (MCP), methyldicyte) in the dicyclopentadiene. Clopentadiene (MDCP)) may optionally be further contained (e.g., a modification component other than DCP may be up to about 20% by weight of the total modification component). In addition, the modifier may be provided in the form of a mixture of dipentene, styrene monomer, vinyl toluene and the like. Of particular note is that the modifier does not intentionally contain at least a certain amount of oligomers of at least trimers of cyclopentadiene, rather than as disclosed in the foregoing prior arts, for example US Pat. Nos. 4,311,826 and 4,391,969, rather The use of modifiers in a form that is substantially free of such oligomers can also achieve the intended technical features. Therefore, it is to be understood that the present invention enables the use of dicyclopentadiene alone as a modifying component. In particular, the modifier may be provided in a form in which the modifying component typically has a purity of preferably at least about 80% by weight, more preferably at least 90% by weight, and most preferably at least 98% by weight. For exemplary compositions of this type of modifier, about 65-75 wt% dicyclopentadiene, about 10-20 wt% cyclopentadiene, about 10-20 wt% derivatives thereof (MCP, MDCP, etc.), and others About 0.1-1.5 weight percent of the component.

In the prior art, the use of unrefined fractions, such as cracker residues in refinery naphtha cracking processes, leads to the generation of adverse odors during manufacturing or use, and due to various substances that are difficult to analyze, It was difficult to fully prove the relationship of. However, in the case of the present invention, it is differentiated by using relatively purified dicyclopentadiene.

On the other hand, according to the present invention, a rapid temperature rise of the reactants occurs due to the exothermic reaction by polymerization of sulfur and the modifier in the production of the modified sulfur binder. This may cause the formation of side products and run-away reactions, it is preferred to slowly add a certain amount of modifier to prevent this. For example, once the sulfur is melted to about 140 ° C., the modifier is slowly added and reacted under melting conditions of about 135 to 145 ° C. (preferably with stirring). At this time, the reaction time is controlled according to the amount of the modifier used, the reaction product is reacted to the point where the tetrahedral crystal content of sulfur in the reaction product is in the range of about 40 to 80% by weight, preferably about 60 to 80% by weight. In particular, the reason why the tetragonal crystal content of sulfur in the present invention is limited to the aforementioned range is because the chemical modification degree of sulfur can be expressed in the desired physical properties and performance as a binder within the above range. For example, when sulfur and dicyclopentadiene-based modifiers are used at 97: 3, the content range of the tetragonal crystals will be reached after typically about 1 to 3 hours at about 140 ° C.

In this regard, the content of the tetragonal crystal may be understood as a concept based on the solid phase, but in the process of measuring the tetragonal crystal content in the modified sulfur binder using solid phase scanning calorimeter (DSC), etc. Since it involves melting, it can be applied to liquid reformed sulfur binders without any particular difficulty.

The reaction product preferably exhibits a viscosity (based on 135 ° C.) of about 10 to 800 cP, more preferably about 10 to 100 cP, upon completion of the reaction.

According to the present invention, the amount of the modifier is used at a level of about 2 to 4% by weight, more preferably about 2 to 3% by weight, and most preferably about 3% by weight, based on the total weight of the reactants. If less than 2% by weight of modifier is used, the content of polysulfide is less than the above-mentioned range because the content of tetragonal crystals in the reaction product which indicates the standard of reaction progress is not particularly differentiated from sulfur before the reaction. It is difficult to expect the effect of the intended sulfur modification. On the other hand, when the amount of the modifier exceeds 4% by weight, it causes a sharp increase in viscosity due to continuous polymerization during liquid phase storage (for example, when stored at 130 to 140 ° C, which is a typical storage temperature).

In this regard, it is interesting to note that even when the amount of the modifier exceeds 4% by weight, even though the tetragonal content of sulfur in the reaction product can meet the required level, the range defined in the present invention (2 to 4% by weight) results in a significant viscosity increase over time in the liquid storage process. This means that even when dicyclopentadiene is used alone as the modifier, the liquid storage stability of the reformed sulfur binder is ensured by adjusting the amount thereof to a specific range, and the reaction product is based on the preparation of the solid reformed sulfur binder. It differs from the prior art which requires the use of a considerable amount of oligomers of at least trimers of cyclopentadiene to maintain a constant viscosity of.

In particular, as described below, when the modified sulfur binder prepared in the liquid phase exceeds 4% by weight in the process of causing a super-cooling phenomenon of the product to achieve the required level of hardness For this reason, the solidification is not performed in a short time even at a temperature significantly lower than the melting point of sulfur, for example, at room temperature, and causes a problem of leaving a lot of time in fact.

According to the present invention, one or two or more of various additives may be used in consideration of characteristics required in the field of application of the modified sulfur binder, which is a final product.

In this connection, about 0.1 to 5% by weight of a plasticizer such as carbon or carbon black may be additionally used as a super-addition to increase the dispersion in the reaction process, based on the total weight of sulfur and modifier. have. In addition, in response to the trend of requiring aesthetic or identification capabilities in construction or civil engineering materials, various pigments known in the art, in particular inorganic pigments (eg iron oxide, etc.), are also based on the total weight of sulfur and modifiers. By adding 0.1 to 5% by weight, modified sulfur binders of various colors can be prepared. In addition, isoamyl acetate or phenethyl alcohol, preferably phenethyl alcohol, in the reaction process for the purpose of fragrance in order to reduce the discomfort due to the irritating smell of sulfur itself, based on the total weight of sulfur and modifier, 2 weight percent may be added. As such, the modified sulfur binder to which the aromatic component is added may improve workability by providing vanilla, rose, and the like during manufacture or construction.

As described above, the storage / transport temperature in the liquid phase of the reaction product obtained by the reaction of sulfur and the modifier is preferably about 130 to 140 ° C, more preferably about 135 ° C. For example, the viscosity range of the liquid reformed sulfur binder during two weeks of liquid storage at about 130 ° C. is preferably about 10-1000 cP, more preferably about 10-500 cP.

In addition, in the present invention, it is preferable that the storage / transfer temperature of the liquid reformed sulfur binder is set to about 2 to 5 ° C. lower than the reaction temperature of the sulfur and the modifier described above. For example, when the reaction temperature is about 140 ° C., the storage temperature is at about 135 ° C. level.

On the other hand, the liquid reformed sulfur binder material usable in the present invention can be transformed into a solidified form in case of long-distance transport or small amount use. That is, the molten reaction product of sulfur and modifier is cooled until the beaker microhardness reaches about 15-30, preferably about 20-30. In this regard, the sulfur reforming binder usable in the present invention should be understood to include a liquid product in which sulfur and a modifier are reacted under melting conditions, or a form in which it is stored as a liquid, or a solidified form as described above.

According to a preferred aspect of the present invention, once the liquid reformed sulfur binder is reacted after or in storage in a reactor, a storage tank or a separate facility, it is cooled to about 120 to 125 ° C, more preferably about 125 ° C. It is separated from the distributor or depositer on a conveying means, such as a conveyor steel belt, and cooled as the conveyor belt progresses. At this time, the cooling atmosphere on a conveyor belt is not specifically limited, For example, normal temperature is possible. This aspect has the advantage of further suppressing the deterioration of the supercooling phenomenon. In particular, the solid-state modified sulfur binder prepared according to the above aspect is advantageous in terms of handling since it has a tendency to self-granulate in the form of flakes during cooling. In addition, it can also cool in the form of hemispheres, a pellet, etc.

asphalt

In the present invention, asphalt may be used in the art in various kinds of civil engineering, in particular road pavement for use without particular limitation. Asphalt is generally present in a solid or semi-solid state at room temperature, but has a property of melt liquefaction upon heating. In the case of petroleum-based asphalt, various types of straight-run asphalt of the refinery process are used as it is, or diluted asphalt obtained by diluting the DC asphalt with paraffin distillate, aromatic, naphthenic oil, or a mixture thereof. Can be used. Asphalt is divided into several grades on the basis of its predominance of hardness, and in this regard, there are penetration, viscosity and compatibility grades.

Asphalt penetration ratings are specified in ASTM D 946 (KS M 2208), which is a method of classifying asphalt using the results of asphalt penetration tests. In other words, the standard needle is introduced into the asphalt for a specified load and time at the reference temperature, and the penetration amount is defined as the penetration of the asphalt. More specifically, it is an index indicating the hardness of asphalt at 25 ° C., which represents the penetration depth of the needle in 0.1 mm units when pressed for 5 seconds with a force of 100 g using the needle of the needle specified in the asphalt. It means hard asphalt. There are five standard invasion grade ranges, such as 40-50, 60-70, 85-100, 120-150, 200-300. Thus, asphalt with a penetration of 40-50 is asphalt that is harder than asphalt with a penetration of 200-300. Representative road paving asphalt produced in Korea is of two types: penetration 85-100 (AP-3) and penetration 60-70 (AP-5).

Another method of grading asphalt is based on viscosity, which is based on the viscosity of the asphalt prior to aging, or on the basis of the viscosity of the aged asphalt after the RTFO test. Divide

In addition, as mentioned above, the method etc. which are based on the commonality of the pavement of asphalt are known.

In the present invention, preferably, asphalt corresponding to the above-mentioned invasion degree 85-100 (AP-3) or invasion degree 60-70 (AP-5) can be used. In addition, the range of viscosity (kinematic viscosity) of typical asphalt is at a level of about 175-350 cSt at 135 ° C.

aggregate

As aggregate for asphalt concrete, coarse aggregates and finely divided aggregates are used. In general, the quality or particle size of the aggregates has a great impact on the performance of the pavement, and the physical-chemical properties vary from place to place. Generally, coarse aggregates mean aggregates that remain in 2.5 mm (No. 8) sieves, while fine aggregates mean aggregates that pass through 2.5 mm sieves and remain in 0.08 mm (No. 200) sieves.

The granularity or quality of aggregates used in asphalt concrete is in accordance with KS F 2357, which is specified for coarse aggregates and fine aggregates for use in bitumen pavement. The KS F 2357 standard is the Korean industrial standard for 'aggregate for bitumen pavement mixture' and specifies the quality of aggregate and the size of coarse aggregate and fine aggregate.

The coarse aggregate is crushed aggregate (crushed stone), crushed slag, crushed gravel, or the like, and preferably contains no harmful substances such as clay, silt, organic matter (see KS F 2357 standard). Fine aggregates are crushed sand (screenings) obtained by breaking rocks, gravel, and the like, natural sand or mixtures thereof, and preferably contain no harmful substances such as dust, clay and organic matter (see KS F 2357 standard). According to the present invention, the aggregate component may be suitably coarse aggregate and / or fine aggregate, depending on the specific use, manufacturer, production site and properties of the aggregate to which the asphalt composition is applied.

filler

In the present invention, fillers known in the art may optionally be used in addition to the above-described modified sulfur binders, asphalt and aggregates in asphalt concrete. As such a filler component, for example, lime powder (lime lime powder), portland cement, slaked lime, fly ash, recovered dust, furnace steelmaking dust, and powders of other suitable mineral substances may be used alone or in combination. Characteristics such as particle size of the filler are described in, for example, the KS F 3501 standard. The filler component may be used in the form of about 1 to 5 parts by weight of super-addition based on 100 parts by weight of asphalt concrete.

On the other hand, if necessary, various additives known in the art may be further used, such as an anti-peeling agent, a fibrous reinforcement material, a freezing retardant material, and an additive for regeneration. For example, such other additives may be used in the form of about 1 to 5 parts by weight of excess additives based on 100 parts by weight of asphalt concrete.

In general, the damage of asphalt concrete appears in various forms, plastic deformation and cracks are typical types of damage. Due to the explosive and heavy traffic demand, the road pavement is getting worse. In addition, general asphalt has a high temperature sensitivity, so the physical properties change with temperature, and in particular, due to the large viscosity decrease (fluidity) due to the temperature rise in summer, the situation is causing pavement damage due to plastic deformation.

The present invention attempts to solve the above-mentioned problems by using the modified asphalt binder with excellent storage stability in a liquid state as much as possible, and at the same time, using it or partially replacing the general asphalt.

In this regard, the asphalt composition according to the present invention is a mixture of the modified sulfur binder and the asphalt in an appropriate ratio (that is, the general asphalt is partially replaced by the modified sulfur binder), and the amount or replacement amount of the modified sulfur binder in the asphalt composition is If less than a certain level, it is difficult to achieve the intended improvement of physical properties compared to general asphalt in the performance such as plastic deformation resistance. On the other hand, as the amount of the modified sulfur binder is increased, the plastic deformation resistance and the indirect tensile strength increase. However, when used in excess of a certain level, it can exhibit a rigid concrete behavior similar to that of ordinary concrete, so it is not suitable as a material for asphalt concrete. The change in the properties of asphalt concrete in relation to the amount of modified sulfur binder is shown in Table 1 below.

Usage of substituted sulfur binder (replacement amount)  Small amount ⇔ large amount Hardness Plastic Strain Resistance Indirect Tensile Strength  Softness Slightly improved Large Slightly high High

Therefore, it is necessary to adjust the usage amount (replacement amount) of the modified sulfur binder in consideration of the intended level of physical properties in the final asphalt concrete. According to the invention, the mixing ratio of the modified sulfur binder and asphalt ranges from about 2: 8 to about 5: 5, preferably from about 3: 7 to about 4: 6, by weight.

Meanwhile, according to the present invention, the above-described modified sulfur binder-containing asphalt composition is mixed with various aggregates to form asphalt concrete. In this regard, the mixing ratio of the asphalt composition and the aggregate may vary depending on variables such as the application of the asphalt concrete in actual use (eg, surface layer or substrate), but the content of the asphalt composition in the asphalt concrete is typically If it is in the range of about 2 to 10% by weight, more typically about 3 to 7% by weight (ie, the aggregate content is typically about 90 to 98% by weight, more typically about 93 to 97% by weight), no particular problem Applicable

According to a preferred embodiment of the present invention, within the range of the mixing ratio of the above-mentioned asphalt composition and aggregate, it is easy to quantify the optimal amount of the asphalt composition (ie, modified sulfur binder and asphalt) with respect to the conventional asphalt amount used conventionally. Can be.

Typically, for asphalt concrete using only plain asphalt (ie, plain asphalt and aggregate), the content of plain asphalt is on the order of about 1-9 weight percent. However, since the specific gravity of the modified sulfur binder is about 1.8 times larger than that of the general asphalt, if it is ignored, the absolute amount of asphalt surrounding the aggregate is insufficient, so that the pavement cannot be properly packed. Therefore, in the case of using only conventional asphalt, in the partial substitution with the modified sulfur binder, the substitution rate (ie, determined in the range of 20 to 50% by weight) is first determined, and then substituted into the following Equation 1 to obtain an appropriate amount of use. Can be.

A = (18000 × B) / (18000-80 × C + B × C × 0.8)

In the above,

A is the amount of asphalt composition when using a modified sulfur binder (ie, modified sulfur binder + normal asphalt; unit is% by weight),

B is the amount (% by weight) of ordinary asphalt used in conventional asphalt concrete, and

C is substitution amount (20-50 wt%)

For example, when 5.8% by weight (B) of ordinary asphalt is used and 30% by weight (C) is substituted with the modified sulfur binder, the calculation result of Equation 1 indicates that the amount of asphalt composition is about 6.6% by weight (A). do. Therefore, the amounts of the modified sulfur binder and the general asphalt may be determined by Equations 2 and 3, respectively.

D = A × C / 100

E = A-D

In the above,

A and C are as described above,

D is the amount of modified sulfur binder used in the asphalt composition (% by weight), and

E is the general asphalt usage (% by weight) in the asphalt composition.

Therefore, in the conventional asphalt concrete, when the amount of the asphalt composition in which the general asphalt is replaced with the modified sulfur binder is 6.6 wt%, the amount of the modified sulfur binder is about 2.0 wt% according to Equation 2, and the amount of the general asphalt is According to equation (3) is about 4.6% by weight.

1 is a view showing the relationship between the amount of general asphalt used in conventional asphalt concrete and the amount of asphalt composition (modified sulfur binder + general asphalt) according to the present invention by using Equation (1).

For example, when using 5.8% by weight of ordinary asphalt (symbol ①), if you want to replace 30% by weight (symbol ②) with modified sulfur binder, the amount of asphalt composition (modified sulfur binder + general asphalt) is 6.6% by weight. (Sign ③).

As described above, in the case of the formula of asphalt concrete, it may be different depending on the composition of the aggregate used, the production site of the aggregate. In addition, the formulation used may vary depending on the manufacturer of the asphalt concrete. However, in case of the base layer, when using the aggregate number '467' mentioned in KS F 2357, asphalt (for example, AP-5) is generally used at about 3.5 to 4.0% by weight, while in the case of surface layer, aggregate is used. When using the number '78', use about 5.5 to 6.0% by weight. Considering the above Equations 1 to 3, the asphalt concrete composition in the representative base layer and the surface layer is shown in Table 2 (substitution rate of the modified sulfur binder: 30% by weight).

division ingredient General asphalt concrete (% by weight) Asphalt concrete of the present invention (% by weight) Substrate ¹ Aggregate # 467 96.0 to 97.5 95.4-96.0 AP-5 3.5 to 4.0 2.8 to 3.2 Reformed Sulfur Binder - 1.2 to 1.4 Pave ² Aggregate # 78 94.0 to 94.5 93.1 to 93.7 AP-5 5.5-6.0 4.4 to 4.8 Reformed Sulfur Binder - 1.9 to 2.1

¹ : located between the surface layer and the auxiliary base layer, and serves to support the traffic load applied to the surface layer;

² : It is the uppermost layer in contact with the traffic load, which distributes the traffic load to the lower floor or prevents rainwater from penetrating and provides friction to the tire.

On the other hand, in the present invention, the process for producing asphalt concrete by mixing the modified sulfur binder with general asphalt and aggregate can be divided into wet and dry methods.

2 is a view schematically showing a process for producing asphalt concrete according to a wet method in one embodiment of the present invention, Figure 3 is a process for producing asphalt concrete according to a dry method in another embodiment of the present invention It is a figure which shows schematically.

In the above embodiment, in order to use the reforming sulfur binder, an asphalt storage tank or a mixing mixer of an existing asphalt concrete plant may be used as it is, and it is sufficient to install only a separate device or process for injecting the reforming sulfur binder.

In the wet method, the asphalt composition is prepared by melting and mixing the modified sulfur binder and the asphalt under the heat mixing conditions at the aforementioned mixing ratio. At this time, it is preferable to set the conditions so that the modified sulfur binder and the asphalt can be uniformly mixed while being melted. For example, the mixing temperature is preferably set to about 130 to 140 ° C, more preferably about 134 to 136 ° C. Can be. At this time, the reformed sulfur binder may be introduced into the storage tank in a liquid or solid form and mixed with asphalt. In particular, the asphalt is preferably introduced in a liquid or molten state by preheating at about 130 to 140 ℃. Although the mixing time in a storage tank is not specifically limited, It is suitable in about 3 to 5 minutes. The asphalt composition is then introduced into the mixing mixer together with the aggregate or sequentially from the storage tank. At this time, the aggregate is preferably preheated to about 150 to 160 ° C. prior to introduction into the mixing mixer. Then, it is preferable that the asphalt and the modified sulfur binder sufficiently surround the aggregate by uniformly mixing the asphalt composition and the aggregate under the heat mixing conditions so that the asphalt composition can maintain the molten state during the mixing with the aggregate. The mixing temperature is preferably controlled under temperature conditions of about 130 to 140 ° C., more preferably about 134 to 136 ° C. to produce heated asphalt concrete. The mixing time is not particularly limited, but is preferably about 0.5 to 3 minutes.

On the other hand, in the dry method, the asphalt, modified sulfur binder and aggregate are supplied to the mixing mixer at once within the above-described composition range and mixed under heating conditions, preferably about 130 to 140 ° C, more preferably about 134 to 136 ° C. By heating asphalt concrete manufacturing process. The properties of the asphalt and modified sulfur binders supplied, and the point of preheating the aggregates, preferably before mixing, are the same as in the wet process. At this time, the mixing time is preferably adjusted to about 0.5 to 3 minutes.

It is preferable that the mixing process accompanying the above-described wet method and dry method involves stirring.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

Example 1

Sulfur and dicyclopentadiene (DCP) were reacted using reactants of the composition shown in Table 1 (based on 100 g total). At this time, the reaction was maintained at the temperature while slowly adding dicyclopentadiene to the sulfur preheated at 140 ℃. In addition, considering that the reaction of sulfur and dicyclopentadiene is exothermic, the temperature increase was not caused, and the total reaction time was about 3 hours. Physical properties (density and viscosity) in the reaction product, and the tetragonal crystal content of sulfur are shown in Table 3 below.

Sample Composition (% by weight) Properties Content of tetragonal crystal ³ (% by weight) brimstone DCP Density ¹ (g / cm 3) Viscosity ² (cP) One 99 One 1.92 11 90 2 98 2 1.90 13 78 3 97 3 1.87 25 67 4 96 4 1.86 43 60 5 95 5 1.83 65 52

¹ : measured according to ASTM D70 at 25 ° C.,

² : measured according to ASTM D4402 at 135 ° C., and

³ : Mean content of tetragonal crystals of sulfur in the modified sulfur binder measured under the trade name Pyris 6 of PerkinElmer.

Example 2

In order to examine the effect of the amount of the modifier on the mechanical properties of the modified sulfur binder, pure sulfur melted at 140 ° C., and samples 1, 3, and 5 in the molten state of Example 1 were cooled, and the hardness over time. D) was measured according to ASTM 2240. The results are shown in FIG.

From FIG. 4, it can be seen that Sample 1 gradually decreases in hardness as time passes, such as pure sulfur, while Samples 3 and 5 gradually increase in hardness.

In addition, after solidifying sample 1 and sample 3 at room temperature, the crystal structure was observed through the electron microscope. The results are shown in FIGS. 5A and 5B, respectively.

According to FIG. 5, sample 1 has a very irregular and large number of crystals, while sample 3 has a relatively small crystal and has a regular arrangement. This shows that in case of sample 1, crystal structure is similar to that of pure sulfur due to excessive crystal growth due to insufficient reforming, while in case of sample 3, excessive chemical growth is alleviated by sufficient chemical modification by using an appropriate amount of modifier. Point. Therefore, it can be seen that Sample 3 can impart excellent characteristics in brittleness, etc. at the time of forming later than Sample 1.

Example 3

The modified sulfur binder (Samples 2 to 5) produced by the reaction according to Example 1 was stored at 130 ° C., and the viscosity change over time was observed. The results are shown in FIG.

As shown in FIG. 6, even when dicyclopentadiene alone is used as the modifier, when the amount of modifier used is adjusted to 2 to 4 wt% (samples 2 to 4), even when stored for 6 weeks or more in the liquid phase, stabilized viscosity characteristics Indicated. On the other hand, when 5% by weight of dicyclopentadiene was used as a modifier (Sample 5), after 3 weeks in liquid storage, although the tetragonal crystal content of sulfur in the binder satisfied the required level of 52% by weight, 10000 cP or more. In summary, it has been found that the amount of the modifier used is an important factor in the liquid shelf life of the reformed sulfur binder. In addition, in view of the more stable storage properties of Samples 2 and 3, it can be seen that the preferred amount of modifier is 2 to 3% by weight.

Example 4

In the present invention, after evaluating the degree of supercooling during the solidification process, 5 g of samples were respectively obtained from the molten reaction product (samples 2 to 5) at 140 ° C. and cooled at room temperature. The time required for the beaker microhardness to reach 15 (minimum) to 30 (maximum) was measured. At this time, the beaker microhardness number was measured by Matsuzawa brand name DMH-1. The test results are shown in Table 4 below.

Sample Total time spent solidifying (minutes) 2 10 to 15 3 15-20 4 20-30 5 50 to 60

In view of the above table, it can be seen that samples 2 to 4 corresponding to the reformed sulfur binder in the liquid phase according to the present invention can suppress the severe supercooling phenomenon compared to sample 5, so that the time required for solidification is considerably low.

Example 5

Using modified sulfur binder (solid powder form) having the composition of Sample 3 of Table 1, asphalt concrete containing the modified sulfur binder was prepared according to the wet method and the dry method as shown in FIGS. 7A and 7B (replacement amount of modified sulfur binder). : 20% by weight).

-Wet method

1) AP-5 grade asphalt was heated to 135 ° C. to have fluidity (viscosity: about 350 cP), and then 1000 g was added to the vessel. Thereafter, a modified sulfur binder (SPC) in the form of a solid powder was poured into a container containing the asphalt at 135 ° C. and melt mixed for 3 minutes (asphalt composition). At this time, the input amount of the modified sulfur binder was adjusted so that the weight ratio of asphalt: modified sulfur binder is 2: 8, mixing was performed under stirring conditions (1000 rpm).

2) The moisture was removed by preheating the aggregate meeting the KS F2357 standard in an oven at 160 ° C. Then, 4680 g of the preheated aggregate was added to the mixed mixer, and then 320 g of the asphalt composition was added thereto. The asphalt composition and aggregate were rapidly mixed under stirring conditions (300 rpm) for 1 minute while maintaining the temperature at 135 ° C.

3) The heated asphalt concrete obtained in step 2) was put into a mold heated to 135 ° C and molded. At this time, a mold was used that meets the test standard described later.

Dry method

1) The aggregate meeting the KS F2357 standard was preheated in an oven at 160 ° C. to remove moisture.

2) Then, the preheated aggregate was added to a mixing mixer, and asphalt (AP 5) heated at 135 ° C. and a reformed sulfur binder in solid powder form were sequentially added to the same mixing ratio as that of the wet method. The mixture was rapidly mixed for 1 minute under a temperature condition of 135 ° C. and a stirring condition (300 rpm).

3) The heated asphalt concrete obtained in step 2) was put into a mold heated to 135 ° C and molded. At this time, a mold was used that meets the test standard described later.

-Asphalt concrete was prepared in the same manner as the dry method described above, while changing the substitution rate of the modified sulfur binder in the asphalt composition to 30% by weight and 50% by weight, respectively. In addition, asphalt concrete was produced without using modified asphalt separately (control tool).

Physical properties of the four samples prepared as described above were measured by the Marshall test method. Marshall test method was performed according to the standard of KS F 2337 as a method of measuring the empirical properties of the asphalt mixture. The purpose of the Marshall test is to measure the strength of asphalt concrete compacted with standard laboratory compaction. The Marshall test is also used as a part of the properties of Marshall formulation design to determine the optimal asphalt content of asphalt mixtures and also applies to the quality control of asphalt concrete. Among the properties measured according to the above test, Marshall stability is a load applied to the specimen (specifically, a cylindrical specimen of 101.6 mm in diameter and 63.5 mm in height) placed sideways, and is a load applied until the specimen is destroyed. Indicates the maximum load. In addition, the flow value (deformation amount) means the total vertical displacement of the specimen up to the point at which the maximum load is reached, and represents the total stock displacement from the starting point of the load until the sample is destroyed. Marshall test method is a representative property value that can measure the performance of domestic asphalt concrete in a simple way, it is used as the basis of the mix design, such as asphalt content and aggregate composite particle size selection.

Marshall test results for the four asphalt concrete prepared as described above are shown in Table 5.

Substitution rate (wt%) Stability (kg) Flow value (1/100 cm) Plain Asphalt Concrete (AP5) 0 1,492 29 Asphalt concrete with modified sulfur binder 20 1,574 30 30 1,756 32 50 1,971 34

According to the results of the above table, according to the present invention, asphalt concrete containing a modified sulfur binder may satisfy the domestic specification, and it may be confirmed that the modification effect is clear, such as being excellent in resistance to flow.

Example 6

In this embodiment, wheel tracking for evaluation of plastic deformation resistance for the asphalt concrete prepared in Example 5 (replacement rate of the modified sulfur binder: 30% by weight) and general asphalt concrete without the modified sulfur binder (control) ) Tests were performed. The wheel tracking test is a type of dynamic repeated creep test developed by the UK's Road Traffic and Transport Research Institute (TRRL), which simulates plastic deformation due to heavy vehicle driving when actual roads are subjected to high temperature environmental conditions. Used to assess liquidity. Although the above-mentioned Marshall Stability Test method can be used to evaluate the flow resistance to some extent, the wheel tracking test is regarded as a more direct evaluation method because the wheels are driven. As a test equipment, a crank-type shift-driven tester was used, and through this, the beam surface of asphalt concrete manufactured in the same shape as the surface layer of the pavement was driven by a solid tire having a predetermined ground pressure and rubber hardness to change the time of wheel settling. Measured. The results of these tests can be calculated to evaluate the plastic deformation resistance of the asphalt mixture. Typically, the physical properties measured through the wheel tracking test have strain and dynamic stability. Among them, the higher the dynamic stability, the greater the resistance to plastic deformation.

The wheel tracking test results are shown in FIGS. 8 and 9.

According to FIG. 8, in the case of general asphalt concrete, the dynamic stability was 792 (times / mm), but in the case of asphalt concrete according to the present invention, 12,352 (times / mm). This means that in the former case, 792 times must be repeated in order to subside 1 mm of the surface by the wheel, while the latter case should be repeated 12,352 times. Therefore, it can be seen that the asphalt concrete of the present invention has about 16 times improved resistance to plastic deformation compared to general asphalt concrete.

Example 7

In this example, the indirect tensile strength test (ASTM D 4123) is performed on the asphalt concrete prepared in Example 5 (replacement rate of the modified sulfur binder: 30 wt%) and general asphalt concrete without the modified sulfur binder (control). It was. Temperature was carried out at low temperature (-10 ℃) and room temperature (25 ℃) respectively. Since the wheel load causes tensile stress at the bottom of the pavement layer, the tensile strength value for the asphalt mixture is one of the most important factors in determining the strength of the asphalt mixture. Tensile strength can be evaluated by indirect tensile strength test, the indirect tensile strength measured through the test is used as one of the important physical properties to evaluate the crack resistance of the pavement.

Indirect tensile strength test results are shown in FIG. 10.

According to Figure 10, it can be seen that the tensile cracking resistance at low and room temperature is significantly improved, such as the indirect tensile strength of the asphalt concrete according to the present invention at room temperature (25 ℃) is about 2.4 times higher than that of ordinary asphalt concrete. .

As described above, the present invention is improved mechanically compared to conventional asphalt concrete while having excellent workability in the production of asphalt concrete using a modified sulfur binder that can be suppressed the change of physical properties such as viscosity in the liquid storage process as possible It has the advantage of giving strength characteristics.

Simple modifications and variations of the present invention can be readily used by those skilled in the art, and all such variations or modifications can be considered to be included within the scope of the present invention.

Claims (13)

Tetrahedral crystals of sulfur in the reaction product, comprising reaction products under melting conditions of 96% to 98% by weight of sulfur and 2 to 4% by weight of a dicyclopentadiene-based modifier containing no oligomer of at least trimers of cyclopentadiene. Asphalt composition, characterized in that it comprises a modified sulfur binder and asphalt in the content of 40 to 80% by weight in a weight ratio of 2: 8-5: 5. The asphalt composition according to claim 1, wherein the asphalt has a penetration of 85 to 100 (AP3 grade) or a penetration of 60 to 70 (AP5 grade). The method of claim 1, wherein the dicyclopentadiene-based modifier further comprises dicyclopentadiene (DCP), cyclopentadiene (CP), derivatives of dicyclopentadiene, derivatives of cyclopentadiene or mixtures thereof as a modifier. Asphalt composition, characterized in that it comprises. The asphalt composition of claim 1, wherein the reaction product has a viscosity of 10 to 800 cP (based on 135 ° C). The asphalt composition according to claim 1, wherein the oil reforming binder has a viscosity of 10 to 1000 cP at a storage temperature of 130 ° C. The asphalt composition of claim 1, wherein the mixing ratio of the modified sulfur binder and the asphalt in the asphalt composition is in the range of 3: 7 to 4: 6. The asphalt composition of claim 1, further comprising 1 to 5 parts by weight of a filler based on 100 parts by weight of the asphalt composition. An asphalt concrete comprising (A) 2 to 10% by weight of the asphalt composition according to claim 1 and 90 to 98% by weight of the (B) aggregate. The asphalt concrete of claim 8, wherein the aggregate meets the KS F 2357 standard. a) melt-mixing the modified sulfur binder and asphalt at a weight ratio of 2: 8-5: 5 under heat-mixing conditions to prepare an asphalt composition; And b) mixing 2-10 wt% of the asphalt composition and 90-98 wt% of the aggregate under heat mixing conditions; Wherein the asphalt composition comprises (i) a reaction product under melting conditions of 96 to 98% by weight of sulfur and 2 to 4% by weight of a dicyclopentadiene-based modifier containing no oligomer of at least trimers of cyclopentadiene; , Modified sulfur binder having a tetragonal crystal content of sulfur in the reaction product in the range of 40 to 80% by weight and (ii) asphalt is a method of producing asphalt concrete, characterized in that consisting of a weight ratio of 2: 8 to 5: 5. The method of claim 10, wherein the mixing temperature in the steps a) and b) is 130 to 140 ℃. Mixing the asphalt, the modified sulfur binder and the aggregate under heat mixing conditions, The modified sulfur binder includes a reaction product under melting conditions of 96 to 98% by weight of sulfur and 2 to 4% by weight of a dicyclopentadiene-based modifier containing no oligomer of at least 3 monomers of cyclopentadiene, and in the reaction product. The tetragonal crystal content of sulfur ranges from 40 to 80% by weight, The weight ratio of the asphalt and the modified sulfur binder is 2: 8 to 5: 5, and Asphalt composition consisting of the asphalt and the modified sulfur binder in the mixture, and the method for producing asphalt concrete, characterized in that the content of aggregate is 2 to 10% by weight and 90 to 98% by weight, respectively. The method for producing asphalt concrete according to claim 12, wherein the mixing temperature is 130 to 140 ° C.

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