KR100788248B1 - An asphalt modifier including vinyl aromatic hydrocarbons and modified asphalt mixture having thereof - Google Patents

Abstract

An asphalt modifier, and a modified asphalt mixture containing the asphalt modifier are provided to prevent the sintering deformation of asphalt by increasing viscosity in summer and to prevent the cracking of asphalt by increasing elasticity in winter. An asphalt modifier 1-40 parts by weight of polystyrene(PS) or HIPS of a vinyl aromatic hydrocarbon; 1-40 parts by weight of SBS or SBR of a conjugated diene block copolymer; 1-30 parts by weight of polyethylene; 1-10 parts by weight of a process oil; and 1-10 parts by weight of a plasticizer. Preferably the plasticizer is at least one selected from calcium stearate, zinc stearate and dimethyl terephthalate. A modified asphalt mixture comprises 1-30 parts by weight of the asphalt modifier; and 70-99 parts by weight of asphalt.

Description

Asphalt modifiers and modified asphalt mixtures comprising vinyl aromatic hydrocarbons {AN ASPHALT MODIFIER INCLUDING VINYL AROMATIC HYDROCARBONS AND MODIFIED ASPHALT MIXTURE HAVING THEREOF}

The present invention relates to an asphalt modifier and a modified asphalt mixture, wherein the modifier is easily dissolved in the asphalt at high temperature to improve the viscosity and elasticity of the asphalt to prevent plastic deformation in the summer, and to prevent various cracks in the winter and A modified asphalt mixture.

In recent years, high-performance packaging that has been endowed with functionality such as permeability and noise reduction has attracted attention. For example, for the purpose of good drainage in rainy weather, there is an open pavement pavement that increases the voids in the asphalt mixture to provide water permeability. The pavement paving not only has permeability due to porosity but also has a function of reducing noise by absorbing vehicle noise into the porous interior when the vehicle passes. In such pavement pavement, the amount of coarse aggregate is relatively higher than that of three aggregates, and as a result, the contact portion between the aggregate and the aggregate is relatively small, which may easily cause cracking in the asphalt binder covering the contact portion. To prevent this, special modifiers are needed that improve the quality of the asphalt binder. In other words, by modifying the asphalt with a special modifier, it is possible to prevent cracks and plastic deformation by improving physical strength such as wear resistance, impact resistance, and flow resistance of the asphalt mixture. The present invention relates to the preparation of special modifiers and mixtures thereof.

As a method for producing the modified asphalt mixture, when the asphalt, aggregate and additives are added to the pug mill in order to prepare ascone in the asphalt concrete plant, the modifier may be added and mixed together. This method is called a plant mix method. When a suitable amount of modifier is added to a pug mill and mixed with asphalt, modified asphalt is formed, and the modified asphalt is coated with aggregate to produce modified ascon. This method is advantageous in that it does not require equipment such as colloid mills or tank rolls than the premix method in which asphalt and modifiers are previously mixed by a colloid mill and transported to the ascon plant in a heated tank roll in a molten state.

However, in the plant mix method, since asphalt production time is only 40 to 50 seconds, it is very important to mix asphalt and modifiers in an instant. For this reason, it is common practice to make the fine powder so that it can be melted in an instant. However, the present patent proposes that the melting of the modifier composition at high temperature occurs by mixing the plasticizer and the process oil. In addition, the modifier is proposed to be a modifier with improved processability to easily coat aggregates in the production of ascones due to the low viscosity at high temperatures.

Most of the conventional modifiers have been limited to the amount of these materials due to the high cost by mixing expensive new polymer resins or thermoplastic elastomers with asphalt and mainly using them for the production of modified asphalt. For this reason, by adding a relatively small amount (usually 3 to 8 parts by weight of asphalt), only a certain improvement in physical properties was inevitable. For example, according to Korean Patent Publication Nos. 1999-0079717 and 2003-0046053, SBS resins, which are relatively expensive, are used as main polymer resins, LDPE according to Patent 1997-0070122, and SBR latex according to Patent 2002-0034496. .

In addition, most of the conventional modified asphalt is in the form of adding one kind of main polymer or rubber to the asphalt and a little additional auxiliary agent. However, the modified asphalt is not suitable for asphalt pavement in areas where hot weather in summer and cold weather conditions in winter are required at the same time, which leads to early pavement problems.

As mentioned above, there are two methods for producing the modified asphalt: pre-mix type (especially 1999-0079717) and plant-mix type (especially 1999-0007510). Silver asphalt and polymer resin (or rubber) are mixed and dispersed well in the mixing tank of the asphalt production plant in advance to make modified asphalt, and transported to the Ascon plant by tank roll and stored in the asphalt storage tank. The stored modified asphalt is pumped to a weighing tank and sprayed to the aggregate in the pug-mill mixer through the spraying equipment and mixed vigorously for 45 to 55 seconds to produce ascone.

The problem of this premixing method is that there is no problem when the viscosity of the modified asphalt produced is low, but when the viscosity is very high, it is transported to the tank roller and transferred from the tank roller to the storage tank of the Ascon plant. The high viscosity makes it almost impossible to operate when conveying to or spraying into a pug-mill mixer from a metering bath. In fact, high viscosity modified asphalt is essential for drainage asphalt pavement and flow resistant asphalt pavement. Another problem is that phase separation occurs between the modified polymer and asphalt during transport to tankroll or for long periods of storage in the Ascon plant storage tank. If phase separation occurs, the modified asphalt cannot function.

On the other hand, in the field mixing method, only the modifier to be added to the asphalt is produced separately, separated from the asphalt, transported to the asphalt concrete plant, and when mixing aggregate and asphalt in the pug-mill mixer process, an appropriate amount of modifier is added and mixed together. Take This method has the advantage of being easy to transport and handle, but the modified modifier is melted into the asphalt within a short mixing time (45-55 seconds) to become modified asphalt, and at the same time the condition that the modified asphalt should cover all aggregate surfaces evenly. Must be satisfied. The present invention is to provide a modified asphalt composition using the modifier composition and the modifier required by adopting the latter in situ method. Accordingly, the present invention provides a modifier composition for producing only the modifier separately.

In addition, in order to develop a modified asphalt that satisfies the pavement problems of hot summer and cold winter at the same time, a technique for making a homogeneous modifier by mixing a material for improving high temperature performance and a material for improving low temperature performance is required. Here, the material that improves high temperature performance refers to a thermoplastic polymer resin ((-5) to (+10) ° C) having a relatively high glass transition point, and such material does not easily deform even when the summer packaging temperature is higher than 60 ° C. Normally, it becomes melt liquid of high viscosity only when it becomes 100 degreeC or more. As such, if the material that is not easily deformed even at high temperature (60 ° C.) is uniformly mixed with asphalt, the high temperature performance of the asphalt is improved to improve plastic deformation resistance of the pavement. However, because these materials have high glass transition points, they harden around 0 ° C, causing significant material shrinkage. For this reason, there arises a problem of easily causing cracking at low temperatures.

On the other hand, polymers that improve low-temperature performance are thermoplastic elastomers or rubbers with double bonds, and generally have a glass conversion temperature in the range of (-30) to (-65) ° C. so that they do not harden even at temperatures below zero and maintain flexibility. do. As such, materials having flexibility even at low temperatures have excellent resistance to various cracks, and thus, when mixed with asphalt, the low temperature performance of the asphalt is improved. However, such a material also has a problem that the plastic viscosity is low when the high temperature easily causes plastic deformation.

Therefore, by using the high-temperature polymer and the low-temperature polymer together as a composition of the modifier can reduce the packaging problems that occur in summer and winter together to extend the packaging life.

In order to solve the above problems, vinyl aromatic hydrocarbons, conjugated diene block copolymers, polyethylenes, process oils, and plasticizers are proposed as modifier compositions. Vinyl aromatic hydrocarbons and polyethylenes improve plastic viscosity in summer to improve plastic deformation. The conjugated diene block copolymer improves elasticity in winter to prevent cracking, and the processor oil and plasticizer are asphalt modifiers and modifiers designed to make the polymers having two different functions compatible with each other. It is an object to provide an asphalt mixture.

According to the invention 1 to 40 parts by weight of vinylaromatic hydrocarbons, 1 to 40 parts by weight of conjugated diene block copolymers, 1 to 20 parts by weight of polyethylene, 1 to 10 parts by weight of process oil, and 1 to 10 parts by weight An asphalt modifier is provided that includes minor plasticizers. When the modifying agent is produced in the asphalt concrete plant, 1 to 30 parts of the modifier is added to 70 to 99 parts of asphalt and an appropriate amount of aggregate and a filler are added to prepare modified asphalt for packing asphalt.

Herein, the vinylaromatic hydrocarbon uses polystyrene (PS) or HIPS, and in general, polystyrene (PS) has high viscosity at high temperature (100 to 150 ° C.), which is not suitable for use as an asphalt modifier, but when used with a plasticizer, Since the viscosity at high temperature becomes low, it becomes possible to use it as a modifier. Another reason for using polystyrene (PS) is that the polymer can be mixed without causing phase separation with the conjugated diene block copolymer SBR or SBS. Therefore, by using this polymer together with SBR or SBS, plastic deformation problems in summer are prevented by high viscosity PS, and various cracks in winter are prevented by elastic bodies such as SBR or SBS. At this time, if the PS content is less than 1 part, the role as a viscosity thickener does not appear, and if it is 40 parts or more, the viscosity is too high.

As the conjugated diene block copolymer, it is preferable to use SBS or SBR which is a thermoplastic elastomer. Both are kinds of rubbers, thermoplastic elastomers that have excellent elastic properties and melt when heated. When the conjugated diene block copolymer is less than 1 part, the elasticity effect cannot be expressed at all, and when it is 40 parts or more, the deformation easily occurs and the support force cannot be secured, so 1 to 40 parts is an appropriate composition content.

Polyethylene (PE), like vinyl aromatic hydrocarbons, acts as a viscosity thickener at high temperatures to reduce plastic deformation. However, since polyethylene has no polarity, adhesion with aggregate is not good, and thus it is not preferable to use a large amount of polyethylene. Therefore, if less than 1 part of PE is added, there is no effect as a viscosity thickener, and if it is 20 parts or more, a problem may occur in the adhesive strength with the aggregate.

Depending on the geopolitical location, climatic conditions may vary and thus the desired modifier composition may vary. In other words, it is possible to focus on preventing plastic deformation by increasing the content of vinyl aromatic hydrocarbons and polyethylene (PE), which act as viscosity thickeners, in the climate of high climate compared to the conjugated diene block copolymer. Care can be taken to prevent cracking by increasing the content of the dieneblock copolymer far above the vinylaromatic hydrocarbon and polyethylene (PE) content. Considering this point, it is possible to construct modified asphalt packaging of various qualities by changing the modifier composition of the present invention.

Process oil refers to all oils including diesel oil, vegetable oil, mineral oil, aliphatic oil, aromatic oil, castor oil and the like. The oil serves as an emulsifier to surround each modified polymer to disperse the modified polymer. If the content is less than 1 part, the effect is insignificant. If more than 10 parts, the material is too soft to serve as a modifier.

As the plasticizer of the composition, at least one of all plasticizers including calcium stearate, zinc stearate, and di-methyl terephtalic acid is preferably used. Plasticizers help to lower the viscosity of polystyrene at high temperatures to function as a modifier. If the added content is less than 1 part, it is not effective at all, and if it is 10 parts or more, the viscosity is too low to be a problem.

The maximum use of modifier is 30:70 for asphalt content and the minimum content is 1:99. The minimum content is negligible and the use effect is negligible. The maximum content greatly improves the viscosity of the asphalt, making it impossible to coat the aggregate. Therefore, the amount of modifier used is preferably in the range of 1 to 30 parts with respect to asphalt.

Hereinafter, embodiments of the present invention will be described in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only the embodiments are to make the disclosure of the present invention complete, and to inform those of ordinary skill in the scope of the invention It is provided for.

Example 1

40 parts by weight of PS, 40 parts by weight of SBR, 15 parts by weight of polyethylene (PE), 2 parts of aromatic oil, and 3 parts of dimethyl terephthalate were placed in a pressure shear mixer, and shear mixed vigorously at 170 ° C. for 1 hour to prepare a homogeneous melt. . When the melt is pushed into the extruder with a confider, it is transferred forward through the extrusion screw and extruded from the extrusion die. The noodle-shaped extrudate is rotated with a high speed rotary blade, finely cut, cooled with water and dried to obtain a polymer modifier.

6 g of the modifier fine particles thus prepared, 1034 g of 19 mm dense surface aggregate aggregate heated to 190 ° C., 66 g of limestone powder, and 60 g of asphalt (AP-3) heated to 170 ° C. were mixed in a Marshall mixer and mixed for 2 minutes. Was placed in an oven at 170 ° C. for 2 hours, taken out, and placed in a marshall mold, and then compacted twice with a marshall compactor to prepare a marshall specimen (diameter 101.6 mm, height 63.5 ± 1 mm). In addition, instead of 6 g of the modifier and 60 g of asphalt for making the modified asphalt, 66 g of asphalt (AP-3) was used and other materials were used in the same manner to prepare a general asphalt marshall specimen. After all the Marshall specimens were cured at room temperature for 24 hours, Marshall specimens for the measurement experiment were completed.

After immersing the prepared Marshall specimen in a constant temperature water bath at 60 ° C for 30 minutes, immediately put it on the Marshall tester, compress it at a speed of 50.8 mm, and measure the strength according to the deformation test (KS F 2337) three times for the same specimen. Marshall stability and flow values for the general asphalt mixture and the modified asphalt mixture were calculated and averaged. The results are shown in Table 1 below.

In addition, a platform with a circular groove with a radius of 50.8 mm is installed at the top and bottom of the Marshall specimen, and the load is loaded at a speed of 50.8 mm / min to measure the strength according to the deformation of the general asphalt mixture and the modified asphalt mixture. It was. At this time, the specimens were stored in a constant temperature bath at 25 ° C. for 3 hours before the test and immediately taken out for use in the test. In this way, the tensile strength and deformation according to ASTM D412, the energy required for the destruction of the specimen was measured three times for each mixture, and the average value thereof is shown in Table 1 below.

Exam name Measurement property General mixture Modified Mixtures of the Invention unit  Marshall test Stability 1220 1920 kgf Flow value 35 42 0.1 mm  Indirect Tension Test The tensile strength 1360 1772 kgf Transform value 15.1 17.6 0.1 mm Breaking energy 1380 1690 kgf mm

As can be seen from Table 1, the quality of the modified asphalt mixture for road pavement using the polymer modifier according to the present invention, the stability is increased by about 57 parts, and the flow value is also increased by 20 parts compared to the general asphalt mixture. It was confirmed that stability properties were greatly improved. Marshall stability is known to be related to plastic deformation resistance and this improvement demonstrates that the plastic deformation resistance of the present invention is significantly improved compared to general asphalt pavement.

In addition, the quality of the modified asphalt mixture according to the present invention was found to increase the indirect tensile strength by 30 parts, the deformation value by 17 parts, and the breaking energy by 22 parts, compared to the general asphalt mixture, and the tensile strength properties were also greatly improved. The tensile strength is directly related to the plastic deformation resistance as well as the Marshall stability, so this value is taken for granted. The increase in this value is known to be associated with the increase in fatigue crack resistance, and the modified asphalt according to the present invention will be significantly improved in fatigue cracking compared to general asphalt pavement.

The modified asphalt mixture prepared using the modifier is expected to be able to prevent plastic deformation due to high viscosity in summer and prevent cracking due to high elasticity in winter.

As described above, the present invention manufactures asphalt modifier by mixing vinyl aromatic hydrocarbon, conjugated diene block copolymer, polyethylene, process oil, and plasticizer, to produce asphalt concrete mixture using the surface layer of asphalt pavement, By using it as an intermediate layer or base material, it is used as a modified asphalt packaging material to prevent plastic deformation due to its high viscosity in summer and high elasticity in winter.

Claims (4)

PS or HIPS which is 1 to 40 parts by weight of vinylaromatic hydrocarbons; SBS or SBR which is 1 to 40 parts by weight of the conjugated diene block copolymer; 1 to 20 parts by weight of polyethylene; 1 to 10 parts by weight of process oil; Asphalt modifier comprising 1 to 10 parts by weight of plasticizer. delete The method of claim 1, As the plasticizer, an asphalt modifier using at least one of all plasticizers including calcium stearate, zinc stearate, and di-methyl tere-phthalic acid. The modified asphalt mixture according to claim 1, wherein 70 to 99 parts by weight of asphalt is mixed with 1 to 30 parts by weight of the asphalt modifier.