KR101239399B1 - Modified asphalt composition and method for preparing the same - Google Patents

Abstract

PURPOSE: A modified asphalt composition is provided to prevent plastic deformation in summer and to prevent all kinds of cracking in winter by improving viscosity and elasticity of asphalt. CONSTITUTION: A modified asphalt composition comprises 85 to 95 parts by weight of asphalt, 2 to 6 parts of ethylene vinyl acetate A, 1 to 5 parts by weight of ethylene vinyl acetate B, 0.65 to 4 parts by weight of SEBS(Styrene Ethylene Butylene Styrene) copolymer, 1 to 2 parts by weight of SBS(Styrene Butylene Styrene), 0.15 to 0.3 parts by weight of cross-linking agent, and 0.2 to 1.0 parts by weight of an adhesion promoter based on 100.0 parts by weight of the modified asphalt composition. A manufacturing method of a modified asphalt composition comprises the following steps. Styrene butylene styrene and styrene-ethylene butylene-styrene are mixed in asphalt in nitrogen gas of 170 to 180°C. A mixture cross-linked with thermoplastic rubber is obtained by adding BPO(Benzoyl PerOxide) to the mixture prepared in the first step. Then, ethylene vinyl acetate A, ethylene vinyl acetate B, and an adhesion promoter are added to the mixture prepared in the second step, and then the resultant is stirred and crushed at the same time.

Description

Modified Asphalt Composition and Method for Preparing the Same

The present invention relates to an asphalt concrete material laid on the road, specifically, to improve the viscosity and elasticity of the asphalt to prevent plastic deformation in summer, and to prevent various cracks in winter modified asphalt having high weatherability and high viscosity A composition and a method for producing the same.

Road paving materials are largely classified into asphalt concrete (hereinafter referred to as asphalt) and cement concrete (hereinafter referred to as concrete) depending on the binder used. Ascon has a higher preference for road pavement as it has the advantages of better ride quality, lower noise and convenient maintenance compared to ready-mixed concrete.

In the case of ascon, it is necessary to improve the performance of ascon pavement material because the temperature of the package increases gradually due to the recent global warming, and the asphalt road is damaged due to the internal temperature of the package rises above 60 ° C in summer.

Asphalt (AP-5), which acts as a binder for ordinary asphalt concrete, is easily deformed with respect to temperature. In order to cope with this, various modified ascons are currently being developed. This method of modifying ascons is mostly a plant-mixing method (Plant-Mix) in which thermoplastic resins or rubbers are introduced into a mixer during the production of ascone, and styrene butadiene styrene (the thermoplastic rubber). Styrene Butadiene Styrene (SBS) and additives are added before the production of ascon (Pre-Mix).

In the plant blending method, asphalt, aggregate, and modifier are mixed together in a pug-mill to prepare ascone in an ascon plant. However, in such a plant mixing method, since the contact time of the thermoplastic resin or rubber mixed with the modifier as heated modifier and asphalt is only 40 to 50 seconds, the modifier is not uniformly mixed during the mixing process and is scattered in a high temperature mixer. Because of the loss, it is difficult to keep the product quality constant.

As described above, in the plant compounding method, the modifier is mainly used when mixing the thermoplastic polymer resin or the thermoplastic elastomer with asphalt. For example, Korean Patent Publication Nos. 1999-0079717 and 2003-0046053 use SBS resins as polymer resins, and Patent Publication No. 1997-0070122 uses low density polyethylene (LDPE) as polymer resins. Patent Publication No. 2002-0034496 uses SBR latex as a polymer resin.

In addition, one type of main polymer or rubber and another auxiliary agent are added to the conventional modified asphalt. However, such asphalt is not suitable for asphalt pavement, which must satisfy both summer and winter climatic conditions.

The premixing method mixes and disperses asphalt and polymer resin (or rubber) in the mixing tank of the asphalt production plant well in advance to make the modified asphalt and transports it to the Ascon plant by tank roll and stores it in the asphalt storage tank. The stored modified asphalt is transported to the weighing tank by a pump and the metered amount is sprayed through the spraying equipment to the aggregate in the pug-mill mixer and mixed vigorously for 45-55 seconds.

This premixing method has high viscosity even at high temperatures (160-170 ° C), resulting in poor workability in the process of producing and constructing the composition, and most of them use SBS, so that the weather resistance is due to the double bonds of SBS itself. This has the disadvantage of falling. Weather resistance refers to a property that withstands external environmental changes (climate changes such as sunlight and weather). When sunlight is prolonged, its molecular structure is deformed and degrades than its original physical properties.

Accordingly, the present inventors have studied to solve the above problems, and as a result, by finding that they can synergistically obtain modified asphalt having high weatherability and high viscosity by mixing specific materials, and completing the present invention. Reached.

It is therefore an object of the present invention to provide a modified asphalt composition having high weatherability and high viscosity and a method for producing the same.

A first aspect of the present invention is to provide a modified asphalt composition having the following components and composition ratios, based on a total of 100 parts by weight of the composition:

-85 to 95 parts by weight of asphalt,

2 to 6 parts by weight of ethylene vinyl acetate A,

1 to 5 parts by weight of ethylene vinyl acetate B,

Styrene ethylene butylene styrene copolymer (SEBS) 0.65~4 parts by weight,

1 to 2 parts by weight of styrene butylene styrene (SBS),

0.15 to 0.3 parts by weight of crosslinking agent, and

0.2 to 1.0 parts by weight of adhesion promoter.

Here, ethylene vinyl acetate A means that the vinyl acetate (VA) content is 10 to 25% by weight, ethylene vinyl acetate B means that the vinyl acetate (VA) content is 25 to 50% by weight.

It is a second aspect of the present invention to provide a method for preparing a modified asphalt composition comprising the following steps:

Adding styrene butylene styrene and styrene ethylene butylene styrene to the asphalt in nitrogen gas at 170 to 180 ° C. and mixing for 2-3 hours to obtain a mixture;

-Adding benzoyl peroxide (BPO) as a crosslinking agent to the mixture obtained in the above step and reacting for 1-2 hours to obtain a mixture crosslinked with thermoplastic rubber; And

Adding a mixture of ethylene vinyl acetate A, ethylene vinyl acetate B and an adhesion promoter to the mixture and pulverizing with stirring using a high speed stirrer for 1-2 hours.

The modified asphalt according to the present invention can obtain a higher commonality by securing high weather resistance in the state exposed to the external environment after the production and construction of modified ascon, thereby increasing the road pavement cycle.

Asphalt used in the present invention is "AP-5". This is one of the asphalt grades, the remaining refined and refined asphalt in refineries (typically asphalt used for pavement).

The amount used is used in an amount of 85 to 95 parts by weight based on 100 parts by weight of the total composition. If the content is less than 85 parts by weight, a relatively large amount of SBS or EVA is used in the asphalt. In this case, the materials are unstable in the asphalt, so that it is difficult to be uniformly dispersed in general. Hard to get good asphalt properties

As a criterion for classifying the properties of asphalt, there is a PG grade according to the “KS F 2389” asphalt compatibility grade, which defines the temperature range in which the manufactured asphalt can be used. Asphalt grades), and PG 76-22 is modified asphalt. The first number is high temperature, the second number is low temperature and it is below zero. Here, the physical property test for high temperature is measured by rheometer measuring device, and in the case of low temperature, the asphalt strength test is performed at low temperature.

Asphalt composition according to the present invention, based on 100 parts by weight of the total composition, 2 to 6 parts by weight of ethylene vinyl acetate A having a VA content of 10 to 25% by weight, and ethylene vinyl acetate B 1 having a VA content of 25 to 50% by weight. It includes -5 parts by weight.

Here, ethylene vinyl acetate B having a high VA content has a low viscosity and may even exist as a liquid at room temperature. In addition, ethylene vinyl acetate A, which has a low VA content, has a high self hardness and has the effect of low dispersibility in asphalt. For this reason, by adjusting the VA content in a suitable combination to increase the adhesion to a relatively high VA content, and to improve the physical properties at high temperatures with a low VA content.

Styrene butylene styrene (SBS) used in the present invention tends to have poor weather resistance as a polymer containing a double bond by itself. Although undergoing a process of reacting a double bond through crosslinking, it is essentially a polymer having poor weather resistance and intends to appropriately adjust its amount.

SBS used in the present invention is used in an amount of 1 to 2 parts by weight based on 100 parts by weight of the total composition. SBS should be used in minimal amounts because of poor weather resistance.

In addition, in the present invention, the styrene ethylene butylene styrene (SEBS) copolymer is used in an amount of 0.65 to 4 parts by weight based on 100 parts by weight of the total composition. SEBS has better weatherability than SBS, but has poor weatherability than EVA, and SEBS and SBS have better mechanical properties than EVA, and thus, the composition ratio is limited to an optimum range in consideration of this.

SEBS and SBS used in the present invention is excellent in viscoelasticity and impact strength. However, since the double unit is included in the repeating unit, the weathering property of the modified asphalt is inferior. Therefore, in the present invention, benzoyl peroxide (BPO) may be added as a crosslinking agent to crosslink the double bonds present in SEBS and SBS to increase the viscoelasticity of asphalt.

In addition, in the present invention, an adhesion promoter is used to improve the bonding strength between asphalt and aggregate, and examples thereof include Wetfix Be ^? (Manufactured by Akzo Nobel Surface Chemistry AB) or tall oil fatty acid polyamine condensates. This adhesion enhancer is an amine-based composite material with ionic properties, which increases the bonding strength between aggregate and asphalt, thereby suppressing the peeling of the asphalt concrete on the road.

In the present invention, such an adhesion promoter is used in a minimum amount of 0.2 to 1 parts by weight based on 100 parts by weight of the total composition, and when more than this amount is used, the physical properties are degraded. However, the minimum amount should be used to promote adhesion.

According to the present invention, styrene butylene styrene (SBS) and styrene ethylene butylene styrene (SEBS) should be added to asphalt in 170-180 ° C. nitrogen gas and mixed for 2-3 hours. In this process, two components of SBS and SBES cause crosslinking reaction and improve weather resistance. Without mixing in nitrogen gas, oxygen in the processing tank will oxidize the asphalt. Since SBS and SEBS are plastic, in order to disperse them through a high speed stirrer, the nitrogen gas must be maintained at a temperature of at least 170 ° C., and the asphalt is oxidized at 180 ° C. or higher.

When benzoyl peroxide (BPO) is added to the mixture obtained in the above step as a crosslinking agent and reacted for 1 to 2 hours, a crosslinking reaction occurs in the thermoplastic rubber to obtain a crosslinked mixture.

Finally, a mixture of ethylene vinyl acetate A having a VA content of 10 to 25% by weight and ethylene vinyl acetate B having a VA content of 25 to 50% by weight was added to the mixture thus obtained at 1,000 to 1,200 rpm for 1 to 2 hours. By grinding simultaneously with stirring using a high speed stirrer, a modified asphalt composition as desired in the present invention is obtained. When the stirring speed is less than 1,000 rpm, when the modifiers are dispersed in the asphalt, the particles of the dispersant modifier are large, so that stability and physical properties deteriorate, so that only optimum stability and physical properties can be obtained in the above range.

As described above, by using a mixture of ethylene vinyl acetate A having a VA content of 10 to 25% by weight and ethylene vinyl acetate B having a VA content of 25 to 50% by weight, it is possible to improve adhesion and improve the physical properties of the asphalt composition at high temperature. It can be done.

The ratio of the modified asphalt composition prepared according to the present invention to the mixed aggregate consisting of the new aggregate, the new stone powder and the filler is preferably used by mixing in a weight ratio of 3.0 to 6.0 to 94 to 97. The new aggregate is preferably one having a particle size of about 13 mm, and the new stone powder is preferably one having a particle size of 6 mm or less. In addition, the fillers include limestone powder, slaked lime, cement, fly ash, recovered dust, steelmaking dust, etc., and the water content should be 1% or less, and the particle size should be used according to the standard of KS F 3501.

The particle size of the aggregate used by adding the modified asphalt composition of the present invention is preferably used as shown in Table 1 below.

Standard particle size of aggregate Sieve size Type of mixture WC-2 WC-3 WC-4 WC-5 13F ^a 20 20F 20R ^a


Pass
mass
percentage
(%) 25 mm - 100 100 100 20 mm 100 90-100 95-100 90-100 13 mm 95-100 72-90 75-90 69-84 10 mm 84-92 56-80 67-84 56-74 5 mm 55-70 35 to 65 45-65 35 to 55 2.5 mm 35-50 23-49 35-50 23-38 0.6 mm 18-30 10 to 28 18-30 10 to 23 0.3 mm 10 to 21 5 to 19 10 to 21 5 to 16 0.15 mm 6 to 16 3 to 13 6 to 16 3 to 12 0.08 mm 4 to 8 2 to 8 4 to 8 2 to 10

Note: ^a WC (Wearing course) means a heated asphalt mixture for surface layers, F is a mixture containing a lot of mineral fillers (stone), and R is a mixture resistant to plastic deformation.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[Example]

<Production of Asphalt Composition>

Example  One

90 kg of "AP-5" as asphalt, 1 kg of styrene butylene styrene (SBS) and 1 kg of styrene ethylene butylene styrene (SEBS) were placed in a large container equipped with a stirrer, sealed by injecting nitrogen gas, and heated to 170 ° C. After that, the mixture was stirred and mixed for 2 hours.

200 g of benzoyl peroxide (BPO) was added to the mixture obtained as a crosslinking agent and reacted for 1 hour to obtain a mixture obtained by crosslinking SEBS and SBS.

To the mixture obtained above, 5 kg of ethylene vinyl acetate A, 2 kg of ethylene vinyl acetate B and Wetfix Be ^? 1,000 for 1 hour by adding 800 g Grinding simultaneously with stirring using a high speed stirrer at rpm yielded 100 kg of the modified asphalt composition targeted in the present invention.

Example  2

90 kg of “AP-5”, 1 kg of styrene butylene styrene and 2 kg of styrene ethylene butylene styrene as asphalt are placed in a large container equipped with a stirrer, sealed by injecting nitrogen gas, heated to 180 ° C., and stirred for 3 hours. And mixed simultaneously to obtain a mixture.

300 g of benzoyl peroxide (BPO) was added to the mixture obtained as a crosslinking agent and reacted for 1 hour to obtain a mixture obtained by crosslinking SEBS and SBS.

To the mixture obtained above, 4 kg of ethylene vinyl acetate A, 2 kg of ethylene vinyl acetate B and Wetfix Be ^? 700 g of the mixture was added and ground simultaneously with stirring using a high speed stirrer at 1,200 rpm for 1 hour to obtain 100 kg of the modified asphalt composition targeted in the present invention.

Example  3

90 kg of “AP-5”, 2 kg of styrene butylene styrene and 1 kg of styrene ethylene butylene styrene as asphalt are placed in a large container equipped with a stirrer, sealed by injecting nitrogen gas, heated to 180 ° C., and then stirred for 2 hours. And mixed simultaneously to obtain a mixture.

200 g of benzoyl peroxide (BPO) was added to the mixture obtained as a crosslinking agent and reacted for 1 hour to obtain a mixture obtained by crosslinking SEBS and SBS.

To the mixture obtained above, 3 kg of ethylene vinyl acetate A, 3 kg of ethylene vinyl acetate B and Wetfix Be ^? 800 g of the mixture was added and ground simultaneously with stirring using a high speed stirrer at 1,100 rpm for 2 hours to obtain 100 kg of the modified asphalt composition targeted in the present invention.

Example  4

90 kg of "AP-5" as asphalt, 1 kg of styrene butylene styrene and 2 kg of styrene ethylene butylene styrene are placed in a large container equipped with a stirrer, sealed by injecting nitrogen gas, heated to 170 ° C., and then stirred for 3 hours. And mixed simultaneously to obtain a mixture.

300 g of benzoyl peroxide (BPO) was added to the mixture obtained as a crosslinking agent and reacted for 130 minutes to obtain a mixture obtained by crosslinking SEBS and SBS.

2 kg of ethylene vinyl acetate A, 4 kg of ethylene vinyl acetate B and Wetfix Be ^? 700 g of the mixture was added and ground simultaneously with stirring using a high speed stirrer at 1,200 rpm for 2 hours to prepare a modified asphalt composition as desired in the present invention.

Example  5

90 kg of "AP-5" as asphalt, 1 kg of styrene-butylene styrene and 3 kg of styrene-ethylene-butylene styrene were placed in a large container equipped with a stirrer, insulated with nitrogen gas, heated to 180 ° C, and then The mixture was obtained by stirring and stirring for an hour.

200 g of benzoyl peroxide (BPO) was added to the mixture obtained as a crosslinking agent and reacted for 2 hours to obtain a mixture crosslinked with SEBS and SBS.

4 kg of ethylene vinyl acetate A, 1 kg of ethylene vinyl acetate B and Wetfix Be ^? 800 g of the mixture was added and ground simultaneously with stirring using a high speed stirrer at 1,000 rpm for 2 hours to obtain 100 kg of the modified asphalt composition targeted in the present invention.

The components and composition ratios used in Examples 1 to 5 are shown in Table 2 below and the unit is kg.

ingredient Example 1 Example 2 Example 3 Example 4 Example 5 AP-5 90 90 90 90 90 EVA (A) 5 4 3 2 4 EVA (B) 2 2 3 4 One SEBS One 2 One 2 3 SBS One One 2 One One BPO 0.2 0.3 0.2 0.3 0.2 Wetfix Be ^? 0.8 0.7 0.8 0.7 0.8

<Production of Ascon>

Example  6

Asphalt concrete (ascon) was prepared according to the conventional method using 45.4 kg of new aggregate having a diameter of about 13 mm, 46 kg of new stone powder having a diameter of 6 mm or less, 3 kg of filler, and 5.6 kg of the modified asphalt composition of Example 1. 1 day at room temperature Cured.

Example  7-10

The amount of new aggregate, new stone powder and filler was used in the same manner as in Example 6, the composition of Example 2 in Example 7, the composition of Example 3 in Example 8, the composition of Example 4 in Example 9, And in Example 10, except that each of the composition of Example 5 was used in the same manner as in Example 6 to produce a modified asphalt concrete.

Comparative example  One

Instead of the modified asphalt according to the present invention using asphalt 5.6 kg of A company manufactured asphalt concrete according to the conventional method. 1 day at room temperature Cured.

Comparative example  2

Asphalt concrete was prepared by the same method as in Comparative Example 1 except for using 5.6 kg of asphalt manufactured by Company B instead of the modified asphalt according to the present invention. 1 day at room temperature Cured.

<Measurement of properties>

For reference, the quality standards of the modified asphalt composition according to KS F 2349 are shown in Table 3 below.

Item Reference value WC-2,3,4 WC-5 Compaction count (times) 50 times each side 75 times on both sides Marshall Stability (N) 5,000 (7,500) ^a or more 6,000 or more Flow value (1/100 cm) 20-40 15-40 Porosity (%) 3 to 6 3 to 5 Saturation degree (%) 65-80 70 to 85 Tensile Strength Ratio (TSR) 0.75 or more Dynamic Stability (times / mm) 750 or more 1,000 or more Tensile Strength Ratio (TSR) = After Water Saturation Specimen Tensile Strength (N / ㎡)
Tensile Strength of Dry Specimen (N / mm2)

^a () is applied to the package which is concerned about plastic deformation due to flow when the traffic volume of a large vehicle is more than 1,000 vehicles in one direction per day, and the number of compaction of specimens is 75 times on both sides.

Marshall stability, flow value, tensile strength ratio and dynamic stability were measured according to KS F 2349 using the asphalt concrete prepared in Examples 6 to 10 and Comparative Examples 1 and 2.

Mixed aggregate
(weight%)
asphalt
Composition
(weight%)


PG rating
Marshall Stability
(N)
Flow value
(1/100 cm) Seal
Strength ratio
(TSR) dynamic
Stability
(Times / mm) aggregate
(13mm) Stone powder
(6mm) filling Reference value
More than 7500 Reference value
20-40 Reference value
0.75 or more More than 2000 Example 6 45.4 46 3 5.6 76-22 11000 33 0.79 4000 Example 7 45.4 46 3 5.6 76-22 11500 32 0.80 3800 Example 8 45.4 46 3 5.6 76-22 10200 33 0.81 4400 Example 9 45.4 46 3 5.6 76-22 14000 33 0.87 5000 Example 10 45.4 46 3 5.6 76-22 12000 32 0.84 4800 Comparative Example 1 45.4 46 3 5.6 76-22 8800 34 0.78 2500 Comparative Example 2 45.4 46 3 5.6 76-22 8900 33 0.77 2600

In the table above, the PG “76-22” rating means that it can be used at temperatures from 76 ° C to 22 ° C. The use of the same amount of mixed aggregate and asphalt in the Examples and Comparative Examples is because it can be evaluated relative to the physical properties under the same conditions.

As shown in Table 4, the asphalt concrete to which the modified asphalt composition of the present invention is added has a higher Marshall stability than the asphalt concrete added to other asphalt products while maintaining the flow rate and tensile strength ratio of KS F 2349 or more. In view of the increase of 115 to 159%, and the increase in dynamic stability up to 146 to 200%, the modified asphalt composition of the present invention proved to be superior to the asphalt of other products.

Claims (5)

Modified asphalt composition having the following components and composition ratio, based on a total of 100 parts by weight of the composition:
-85 to 95 parts by weight of asphalt,
2 to 6 parts by weight of ethylene vinyl acetate A,
1 to 5 parts by weight of ethylene vinyl acetate B,
0.65-4 parts by weight of styrene ethylene butylene styrene copolymer (SEBS),
1 to 2 parts by weight of styrene butylene styrene (SBS),
0.15 to 0.3 parts by weight of crosslinking agent, and
0.2 to 1.0 parts by weight of adhesion promoter.
The modified asphalt composition of claim 1, wherein the ethylene vinyl acetate A has a vinyl acetate (VA) content of 10 to 25 wt% and the ethylene vinyl acetate B has a vinyl acetate (VA) content of 25 to 50 wt%. .
delete Method for producing a modified asphalt composition comprising the following steps:
Adding styrene butylene styrene and styrene ethylene butylene styrene to the asphalt in nitrogen gas at 170 to 180 ° C. and mixing for 2-3 hours to obtain a mixture;
-Adding benzoyl peroxide (BPO) to the mixture obtained in the above step and reacting for 1-2 hours to obtain a mixture crosslinked with thermoplastic rubber; And
Adding to the mixture a mixture of ethylene vinyl acetate A, ethylene vinyl acetate B and an adhesion promoter and pulverizing with stirring at a speed of 1000 to 1200 rpm for 1 to 2 hours.
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