KR100951466B1 - Modifier composition for warm asphalt, manufacturing method of the modifier and producing method of warm asphalt mixture using the modifier - Google Patents

Abstract

PURPOSE: A modifier composition for warm asphalt is provided to lower a mixing temperature of aggregate and asphalt in a production process of an asphalt mixture and to reduce CO2 amount generated in the asphalt mixture. CONSTITUTION: A modifier composition for warm asphalt comprises a styrene-butadiene block copolymer in which the content of styrene is 10~25 weight%, a styrene block ratio of 40~70 %, and average molecular weight is 50,000~90,000; and wax in which a softening point is 90~140 °C and a viscosity at 140 °C is 15~300 cps. The weight ratio of the styrene-butadiene block copolymer : wax is 1.5~5 : 1.5~5. The wax is any one selected from polyethylene wax, polyamide wax, hydroxyl wax, stearamide wax, polyolefin wax, polypropylene wax, and ethylene propylene wax.

Description

Modified composition for warm asphalt, manufacturing method of the modifier and producing method of warm asphalt mixture using the modifier

The present invention lowers the mixing temperature of asphalt and aggregate in the production process of the asphalt mixture to about 30 ~ 80 ℃ or less compared to the existing heating asphalt mixture to reduce the use of heating fuel and at the same time significantly reduce the amount of CO ₂ generated during asphalt mixture production In addition, the present invention relates to a medium temperature asphalt additive composition capable of improving plastic deformation and crack resistance of asphalt pavement, a method for preparing such an additive, and a method for producing a medium temperature asphalt mixture using the additive prepared by the method.

The heated asphalt pavement is constructed with a mixture of asphalt and aggregate (asphalt mixture), which must be heated to a high temperature of 160 ~ 200 ℃ for mixing asphalt and aggregate. Asphalt pavement constructed at such a high temperature has a problem that the traffic opening time is delayed by the time required to cool near room temperature, and workers are exposed to the risk of harmful gases and safety accidents. Furthermore, not only a large amount of fuel is required to heat the aggregate and asphalt, but also a problem in which harmful emissions such as CO ₂ are increased during production and construction of the asphalt mixture. Therefore, in recent years, in order to solve the above problems, research on a medium-temperature asphalt pavement technology for lowering the production temperature of the asphalt mixture is actively being conducted.

Warm asphalt paving technology is a method of producing and packing asphalt mixture at a temperature of about 90 ~ 150 ℃. (1) Suppressing the generation of various harmful gases during the production and construction of asphalt mixture (the temperature decreases by 10 ℃). Toxic gas emissions can be reduced by half), (2) petroleum-based fuel can be reduced by more than 30% during the production of asphalt mixtures, and (3) traffic can be opened faster by reducing curing time after construction. , (4) There are many advantages such as no harmful vapor or dust generated at the construction site to ensure worker safety.

Mid-temperature asphalt pavement technology having the above advantages is the most typical to realize by adding an additive that softens the asphalt, the wax-based additive is the most used as an additive. Representative wax-based additives include a sasobit wax produced by Sasol. However, conventional wax additives have been shown to increase the stiffness and decrease the stiffness (m-value) in the evaluation of the aging characteristics of asphalt over a long period of time due to the use of wax. I could confirm that. Accordingly, the conventional wax-based additives are known to act as a factor causing low temperature cracking of the asphalt.

The present invention has been developed to solve the above-described problems, to provide a novel wax-based additive composition and a method for preparing the wax-based additives that can compensate for the low temperature properties of the asphalt, which is a problem of the conventional wax-based additives. There is a technical problem.

In addition, the present invention has another technical problem to provide a method for producing a medium-temperature asphalt mixture as a preferred method of using a new wax-based additive.

In order to solve the above technical problem, the present invention proposes a medium temperature asphalt additive composition, a method for preparing a medium temperature asphalt additive, and a method for producing a medium temperature asphalt mixture.

Middle temperature asphalt additive composition according to the present invention, the styrene content of styrene-butadiene block copolymer having a styrene content of 10 to 25% by weight, a styrene block rate of 40 to 70% and a weight average molecular weight of 50,000 to 90,000; And a wax having a softening point of 90 to 140 ° C. and a viscosity of 140 ° C. to 15 to 300 cps. The weight ratio of the styrene-butadiene block copolymer: wax is 1.5 to 5: 1.5 to 5. It is done.

Middle temperature asphalt additive manufacturing method according to the present invention, (a) adding the above-mentioned asphalt additive composition to the melt kneader and mixing at 80 ~ 120 ℃; (b) discharging the mixture of step (a) through a discharge die in a strand form; (c) cooling the discharge in the form of strand of step (b); And, (d) cutting the coolant of the step (c) in the form of pellets; Characterized in that comprises a.

Medium temperature asphalt mixture production method according to the present invention, by producing by mixing the medium temperature asphalt additive prepared by the above-described method, the asphalt melted at 90 ~ 180 ℃, the aggregate heated at 90 ~ 150 ℃ together into a plant mixer, The mesophilic asphalt additive prepared by the above method is melt-mixed at 90 to 180 ° C with asphalt, and the mixed asphalt is produced by injecting and mixing the mixed asphalt with aggregate heated at 90 to 150 ° C.

According to the present invention, the following effects can be expected.

First, it is possible to provide a wax-based additive capable of producing high quality mesophilic asphalt mixture. That is, since the medium-temperature asphalt additive according to the present invention improves plastic deformation resistance without causing an increase in the viscosity of the asphalt when it is mixed with the asphalt, compared with the conventional polymer wax-based additives, it compensates for the low temperature characteristics of the asphalt, By using the mesophilic asphalt additive according to the present invention, it is possible to produce a high quality asphalt mixture.

Second, since the melting time is not long, it is possible to provide a wax-based additive capable of producing an asphalt mixture simply as a premix type for mixing asphalt and additives in advance, as well as a plant mix type for mixing with aggregate in a plant mixer.

Third, since the medium temperature asphalt mixture can be produced in the plant mix type, asphalt paving can be performed while enjoying all the advantages of the plant mix type together with the medium temperature asphalt mixture. That is, while reducing the heating energy, while suppressing the generation of various harmful gases and ensuring the safety of the worker can perform the asphalt paving construction, and further open the traffic as soon as possible after the asphalt paving construction. In addition, pavement work can be easily carried out in short sections, which are difficult to apply the premix type, or sections in which accessibility is not easy.

The present invention is characterized in that SB rubber (styrene-butadiene block copolymer) is used as a material for the medium temperature asphalt additive together with the wax. Conventionally, SBS rubber (styrene-butadiene-styrene block copolymer) is used together with wax to realize mesophilic modified asphalt. However, SBS rubber used for asphalt modification has high viscosity and is limited to realizing mesophilic modified asphalt. There is a limit to offset the low temperature characteristic degradation caused by wax. Accordingly, the present invention realizes PMA (Polymer Modified Asphalt) type mesophilic modified asphalt by using SB rubber and wax having a different structure from SBS rubber instead of SBS rubber. As described above, the present invention relates to a wax-based additive using SB rubber, and proposes a method for producing a medium-temperature asphalt mixture as a preferable composition as an additive, a method for preparing the additive, and a preferred method for using the additive.

1.Medium Temperature Asphalt Additive Composition

The medium-temperature asphalt additive composition according to the present invention uses a special SB rubber (styrene-butadiene block copolymer) which is distinguished from general SBS rubber as shown in Table 1 below, wherein the SB rubber is formed together with the wax. At this time, the weight ratio of SB rubber and wax is 1.5-5: 1.5-5, More preferably, it is 2-4: 2-4. SB rubber and wax must be formulated in the above weight ratio to maximize the advantages of each and can be completed with a high-quality neutralized asphalt additive offsetting the disadvantages. In other words, when the composition is in the above weight ratio, the high-temperature medium temperature lowers the mixing temperature of asphalt and aggregate while suppressing the increase of the viscosity of asphalt by SB rubber with wax while suppressing the low temperature characteristic of asphalt by wax with SB rubber. It is finished with asphalt additives.

Rubber properties SB Rubber Plain SBS rubber Molecular structure Styrene-butadiene Styrene-butadiene-styrene Weight average molecular weight 50,000-90,000 80,000 ~ 250,000 Styrene Content (%) 10-25 25-40 Styrene Block Rate (%) 40-70 100

In the medium-temperature asphalt additive according to the present invention, the SB rubber should be a material having a styrene content of 10 to 25% by weight, a styrene block rate of 40 to 70%, and a weight average molecular weight of 50,000 to 90,000. If the styrene content is 10% by weight or less, it is difficult to pelletize the mixture while mixing with wax, and it is difficult to drop the softening point of the asphalt. If the styrene content is 25% by weight or more, the effect of improving the low temperature property of the asphalt is significantly reduced. In addition, when the styrene block rate is 40% or less, the rubber elasticity is weakened and the high temperature physical property of the asphalt is lowered. When the styrene block rate is 70% or more, the rubber viscosity is weakened and the low temperature physical property of the asphalt deteriorates. Furthermore, if the weight average molecular weight is 50,000 or less, the high temperature property of the asphalt is lowered, and if it is 90,000 or more, it is not good to increase the viscosity of the asphalt. As shown in the following experimental example, the actual SB rubber serves as a special structure to alleviate the low temperature characteristic degradation caused by wax use by improving the stiffness and stiffness change rate (m-value) after PAV among the physical properties of asphalt. It can be confirmed that.

In the middle-temperature asphalt additive according to the present invention, the wax may be used as it is in the conventional wax-based additives, and specifically, polyethylene wax, polyamide wax, hydroxy wax, steamide wax, polyolefin wax, polypropylene wax, ethylene Propylene wax and the like. However, the wax has a softening point of 90 ~ 140 ℃ and a viscosity of 140 ℃ 15 ~ 300cps. If the softening point is 90 ° C. or less, it is difficult to improve the plastic deformation resistance of the asphalt, and if it is 140 ° C. or more, there is a problem that it is difficult to melt when mixing with asphalt. In addition, when the viscosity of 140 ° C is lower than 15 cps, it is difficult to achieve crystallization, and when it is 300 cps or more, the neutralizing effect when mixed with SB rubber is not large.

2. Method for manufacturing medium temperature asphalt additive

The above-mentioned medium-temperature asphalt additives can be used for the production of medium-temperature asphalt mixtures of the plant mix type as well as the premix type. However, since SB rubber hardly improves high-temperature properties of asphalt, such as softening point when mixed with asphalt, and the product is bale-shaped, it is difficult to use SB rubber alone in the production of plant mix type asphalt mixture. Thus, the present invention proposes to produce a medium-temperature asphalt additive in the form of pellets (pellets) to be used in the production of plant mix type asphalt mixture. In other words, the SB rubber is integrated with the wax used together and is commercialized as a medium temperature asphalt additive.

Specifically, the pelletizing process of the middle temperature asphalt additive, (a) adding the middle temperature asphalt additive composition to the melt kneader and mixing at 80 ~ 120 ℃; (b) discharging the mixture of step (a) through a discharge die in a strand form; (c) cooling the discharge in the form of strand of step (b); (d) cutting the coolant of step (c) into pellets; and proceeds by including. If the temperature is less than 80 ℃ melt mixing is difficult and if it exceeds 120 ℃ difficult to discharge in the form of strands, 80 ~ 120 ℃ range is preferred. If the product in the form of pellets (medium-temperature asphalt additive) manufactured through the steps (a) to (d) may be left as it is, aggregation may occur, so that the release agent on the surface of the product in the form of pellets after step (d) It is preferable to further proceed with step (e) of treating the powder. At this time, the release agent powder is suitably about 0.1 parts by weight with respect to 100 parts by weight of the pellet product. The mold release agent powder is not particularly limited, and examples thereof include talc, calcium carbonate, zinc stearic acid and calcium stearic acid.

3. Medium temperature asphalt mixture production method

The middle temperature asphalt additive prepared by the above-described method may be mixed with asphalt and aggregate by one of the following two methods to produce a middle temperature asphalt mixture of 90 to 180 ° C. Here, the asphalt is not particularly limited as asphalt used for road pavement, but considering the use of AP-3 having an intrusion degree of 80 to 100 and AP-5 having an intrusion degree of 60 to 80 as road paving asphalt. The same may be used in the invention.

The first method of producing a medium-temperature asphalt mixture is to improve the medium-temperature asphalt additive prepared in pellet form to the weight required for producing one batch of the asphalt mixture, and then heat it with the molten asphalt (90-180 ° C.) melted at this temperature. It is a method of directly inputting the plant mixer with aggregate (90 ~ 150 ℃). At this time, the medium-temperature asphalt additive improved to the required weight is prepared in a plastic bag to be put into the plant mixer. This method has the advantage that it can be applied to all conventional asphalt plants without the need of installing additional equipment in the asphalt plant. However, this method has a disadvantage that it is necessary to continuously add the medium-temperature asphalt additive to the attraction force, the mixing time is slightly longer, and it is difficult to mix perfectly with asphalt.

In the second method of producing a mesophilic asphalt mixture, the mesothelial asphalt additive prepared in pellet form is heated (90 ~ 180 ° C) and melted together with the asphalt, and then the mixed asphalt (asphalt + mesophilic asphalt additive) is heated (90 ~ 150 ℃) and into the plant mixer. At this time, the medium-temperature asphalt additive is to be stored in a separate tank, and the mixed asphalt is injected into the plant mixer. This method needs to improve the asphalt nozzle in the asphalt plant as shown in FIG. 1 in order to allow the natural asphalt mixture to mix naturally with the asphalt. This method can automatically add mesophilic asphalt additives without dependence on manpower, almost perfectly mix mesophilic asphalt additives and asphalt, and maintain the mixing time with aggregates almost similar to that of ordinary asphalt mixtures. The production efficiency of is also advantageous in that it can be increased. However, this method requires a special asphalt nozzle as shown in FIG. 1 in the asphalt plant, and also requires additional facilities such as a storage tank and a heating device of the medium-temperature asphalt additive.

Meanwhile, in order to produce a medium-temperature asphalt mixture, asphalt and aggregate should be composed of 3.0 to 7.0 wt% of asphalt and 93.0 to 99.0 wt% of aggregate, while medium to moderate asphalt additives should be 1.0 to 10 parts by weight based on 100 parts by weight of asphalt. It is desirable to design.

When asphalt is used less than 3.0% of the aggregate, the asphalt coating rate of the aggregate is low, and the durability of the asphalt mixture is low. In addition, when the asphalt is used in excess of 7.0%, the amount of asphalt remaining after the 100% coating of the aggregate occurs to soften the asphalt mixture, thereby causing plastic deformation.

Mid-temperature asphalt additives are used to reduce the viscosity of asphalt during asphalt mixture production and construction, so they are determined by the ratio of the weight of the asphalt, and it is advantageous to improve the density and recovery elastic modulus when used at 1.0 to 10% by weight. There is.

Hereinafter, the present invention will be described in more detail based on experimental examples. However, the following experimental examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Experimental Example]

(1) experimental materials

The experimental materials were rubbers having physical properties shown in Table 2, asphalt having an AP-5 grade of penetration 70, polyethylene wax having a softening point of 110 ° C., a viscosity of 140 ° C. of 30 cps, and a specific gravity of 0.93.

Rubber Properties of Test Materials SB Rubber SBS1 SBS2 Molecular structure Styrene-butadiene Styrene-butadiene-styrene Styrene-butadiene-styrene Weight average molecular weight 80,000 110,000 80,000 Styrene Content (%) 25 30 30 Styrene Block Rate (%) 60 100 100 Asphalt Softening Point (4.5% Mix) 53 ℃ 80 ℃ 65 ℃

(2) preparation of asphalt additives

Asphalt additive was prepared with the composition shown in Table 3 below with the experimental materials prepared above. In Comparative Examples 1, 2, 3, and 4, rubber and wax were separately prepared according to the conventional method of using the additive, and Examples 1, 2 and 3 were prepared by preparing the additive in pellet form according to the present invention.

Asphalt additive composition division Asphalt additive composition (% by weight) SB Rubber SBS1 SBS2 Wax Control - - - - Comparative Example 1 - 100 - - Comparative Example 2 - - - 100 Comparative Example 3 - - 45 55 Comparative Example 4 52 48 Example 1 40 60 Example 2 45 - - 55 Example 3 52 - - 48

(3) mixed asphalt production

Asphalt and asphalt additives were prepared in the composition shown in Table 4 based on 600 g of asphalt. Comparative Examples 1, 2, 3, 4 and Examples 1, 2, and 3 were prepared by mixing asphalt asphalt at room temperature with asphalt heated in a range of 140 ° C. (asphalt + asphalt additive).

Mixed asphalt composition division Mixed asphalt composition (parts by weight) Asphalt additive composition (parts by weight relative to asphalt) asphalt Asphalt additives SBS1 SBS2 SB Rubber Wax Control 100 - Comparative Example 1 100 3.00 3.00 Comparative Example 2 100 2.50 2.50 Comparative Example 3 100 4.55 2.05 2.50 Comparative Example 4 100 5.22 2.72 2.50 Example 1 100 4.17 1.67 2.50 Example 2 100 4.55 2.05 2.50 Example 3 100 5.22 2.72 2.50

(4) Evaluation of Mixed Asphalt Properties

Checking the physical properties of each mixed asphalt, it was shown as Table 5 below.

Mixed Asphalt Properties original RFTO PAV Viscosity (140, cps) G * / sinδ (70, Pa) G * / sind (70, Pa) stiffness (-12, MPa) m-value (-12) Control 600 600 1,100 190 0.34 Comparative Example 1 1,200 1,300 2,900 240 0.31 Comparative Example 2 480 800 1,800 260 0.28 Comparative Example 3 800 1,400 2,900 250 0.28 Comparative Example 4 900 1,500 3,100 250 0.28 Example 1 550 1,100 2,700 220 0.30 Example 2 600 1,200 2,800 220 0.31 Example 3 650 1,300 2,900 210 0.32 RTFO: Simulates the aging process of mixing with aggregate, transporting and laying the aggregate at high temperature in the initial plant during the production of asphalt mixture PAV: Evaluation of the aging of asphalt over time

As shown in Table 5, it can be seen that the medium-temperature asphalt additive according to the present invention exhibits excellent overall physical properties.

Since the mixed asphalt of Comparative Example 1 can be confirmed that the G * / sin δ is improved in the original and RTFO compared to the control example to improve the plastic deformation resistance, the asphalt additive of Comparative Example 1 can be used as a general asphalt additive. However, since the viscosity appears to increase greatly from 600 cps to 1,200 cps, when the mixed asphalt of Comparative Example 1 is used to produce the asphalt mixture, it is expected that a high temperature is required for mixing with the aggregate. It is difficult to use for the production of medium temperature asphalt mixture.

Since the mixed asphalt of Comparative Example 2 shows a decrease in viscosity in Original, but a slight increase in G * / sind, compared to the comparative example, the asphalt additive of Comparative Example 2 may be referred to as a moderately warmed asphalt additive with a slight modification effect. In addition, the mixed asphalt of Comparative Example 2 can be confirmed that the low temperature characteristics of the asphalt, such as increased stiffness and reduced m-value after PAV compared to the control example, using the asphalt additive of Comparative Example 2 Low temperature cracking of the packaging is a concern.

As compared with Comparative Example 1, the mixed asphalt of Comparative Example 3 showed an improvement in G * / sind while the viscosity was lowered by 300 cps than that of Comparative Example 1, so that the asphalt additive of Comparative Example 3 had a moderately modified asphalt with good modifying effect. It may be referred to as an additive. However, in the mixed asphalt of Comparative Example 3, the stiffness and the m-value are shown in the same manner as in Comparative Example 2 after PAV, resulting in the same problem (cold cracking of asphalt pavement). Also in Comparative Example 4 with an increased SBS content, similar results to Comparative Example 3 were obtained.

On the other hand, the mixed asphalt of the embodiment can be seen that the effect of improving the plastic deformation resistance shown in Comparative Examples 1 to 4 while maintaining the viscosity similar to the control example. Furthermore, it can be seen that the stiffness and m-value values after PAV are improved compared to Comparative Examples 2-4. Accordingly, the asphalt additive of the embodiment may be preferably used as a medium-temperature asphalt additive to induce the effect of improving the plastic deformation resistance as well as the viscosity lowering effect and at the same time to compensate for the low temperature characteristics of the asphalt.

(5) Production of medium temperature asphalt mixture

Asphalt and aggregate were designed to be 5.1 wt% asphalt and 94.9 wt% aggregate, and the intermediate asphalt additive was added while varying from 0 to 5.0 wt% with respect to the asphalt content to produce a moderate asphalt mixture. The middle temperature asphalt mixture was produced by mixing the asphalt at 150 ° C., the aggregate heated at 130 ° C., and the normal temperature at room temperature asphalt additive in a plastic bag at the same time into a plant mixer. The middle temperature asphalt additive used at this time is prepared by the composition according to Example 2 in Table 3. The temperature of the produced medium-temperature asphalt mixture was found to be 120 ~ 130 ℃, and the sample was prepared by measuring the density and recovery modulus of elasticity. The measurement results are shown in Table 6 below.

Changes in Density and Recovery Modulus of Middle-Medium Asphalt Mixtures According to Additive Use Ratio Additive ratio (wt%) Density (g / cm ³ ) Recovery modulus of elasticity (GPa) 0 2.431 1.26 1.5 2.433 1.28 2.0 2.435 1.32 2.5 2.438 1.43 3.0 2.441 1.62 4.0 2.442 1.72 4.5 2.444 1.75 5.0 2.445 1.76

As shown in Table 6, it was shown that the density and recovery modulus of elasticity increased as the use rate of the medium-temperature asphalt additive increased. Increasing the density means that the compaction effect is improved, and as the use ratio of the medium-temperature asphalt additive increases, the compaction can be made at a lower temperature as well as more effective compaction at the same temperature. In addition, the recovery elastic modulus is related to the durability of the asphalt pavement to the continuous traffic load, it is expected that the durability becomes better as the use ratio of the medium-temperature asphalt additive according to the present invention increases.

1 illustrates an asphalt nozzle used in the method for producing a mesophilic asphalt mixture according to the present invention.

Claims (9)

Styrene-butadiene block copolymers having a styrene content of 10 to 25% by weight, a styrene block rate of 40 to 70%, and a weight average molecular weight of 50,000 to 90,000; And, Consists of a softening point of 90 ~ 140 ℃ and a wax of 140 ℃ ℃ 15 ~ 300cps; The styrene-butadiene block copolymer: the weight ratio of wax is 1.5 to 5: 1.5 to 5, the medium temperature asphalt additive composition characterized in that the composition. In claim 1, The wax is any one of polyethylene wax, polyamide wax, hydroxy wax, steamide wax, polyolefin wax, polypropylene wax, ethylene propylene wax. (A) step of mixing the intermediate temperature asphalt additive composition of claim 1 in the melt kneader and mixing at 80 ~ 120 ℃; (b) discharging the mixture of step (a) through a discharge die in a strand form; (c) cooling the discharge in the form of strand of step (b); (d) cutting the coolant of step (c) into pellets; Method for producing a medium temperature asphalt additive, characterized in that it comprises a. 4. The method of claim 3, After step (d), (e) treating the surface of the product in the form of pellets with the release agent powder; a method for producing a moderate-temperature asphalt additive, further comprising. In claim 4, The step (e) is a method for producing a medium-temperature asphalt additive, characterized in that the processing to 0.1 parts by weight of the release agent powder with respect to 100 parts by weight of the product in the form of pellets. The method of claim 4 or 5, The release agent powder is a method of producing a moderate temperature asphalt additive, characterized in that any one of talc, calcium carbonate, zinc stearic acid, calcium stearic acid.  Method for producing a mesophilic asphalt mixture, characterized in that the medium-temperature asphalt additive prepared by the method of claim 3, the asphalt melted at 90 ~ 180 ℃, the aggregate heated at 90 ~ 150 ℃ by mixing together in a plant mixer to produce . The mesophilic asphalt additive prepared by the method of claim 3 is melt-mixed with the asphalt at 90 ~ 180 ℃, and the mixed asphalt is produced by mixing with the aggregate heated to 90 ~ 150 ℃ in a plant mixer. Method for producing a medium temperature asphalt mixture. In claim 7 or 8, The asphalt and aggregate is designed to be composed of 3.0 to 7.0% by weight of asphalt and 93.0 to 99.0% by weight of aggregate, The middle temperature asphalt additive is a method for producing a medium temperature asphalt mixture, characterized in that the composition is designed to 1.0 to 10.0 parts by weight based on 100 parts by weight of the asphalt.

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