KR102450091B1 - Recycled aggregate medium temperature asphalt mixture - Google Patents

Abstract

The present invention relates to a recycled aggregate medium-temperature asphalt mixture comprising asphalt, new aggregate, recycled aggregate, a filler, a thermoplastic elastomer, polyethylene wax, sulfur powder, and alkyl pyridinium salt. The present invention is to provide an asphalt mixture which is eco-friendly by using recycled aggregate, has the advantage of improving crack resistance, and can improve physical properties such as water resistance.

Description

Recycled aggregate medium temperature asphalt mixture

The present invention relates to an asphalt mixture capable of improving physical properties such as crack resistance and water resistance even when recycled aggregate is used.

The existing recycled aggregate recycling technology aims to restore the properties of the new asphalt concrete with normal quality by mixing the waste asphalt concrete, new asphalt concrete, and oil-based regenerating additives together. However, the physical properties of the existing recycled asphalt concrete always fall short of the properties of the new asphalt concrete.

One of the main reasons is that the formulation design is carried out according to the waste asphalt cone prior to regeneration, but the actual regeneration is carried out in the subsequent high-temperature heating process, so that the formulation design and actual conditions may be different.

Additional oxidative aging of the waste asphalt due to heating in the regeneration process tends to cause premature cracking of the pavement. To overcome this, early cracking is prevented by adding more asphalt content than usual, but in this case, plastic deformation occurs. For this reason, the existing waste asphalt concrete recycling and pavement technology is not free from problems such as fatigue cracking, plastic deformation, and porthole generation.

For the above reasons, the existing waste ascon recycling technology limits the amount of waste ascon used, because the more the amount of waste asphalt concrete added, the worse the packaging quality.

As an example of the prior art related to such recycled aggregate, Korean Patent Registration No. 0317436 limits the mixing rate of waste asphalt to 30 to 50% by weight of new material when recycling waste asphalt, and SBR latex ( Latex), EVA, SBS, SIS, or waste tire powder with a maximum size of 2mm, etc., are prepared by melting asphalt with asphalt at a high temperature and using it together with a regenerating additive.

However, even in the case of the above technology, there is a problem that it is difficult to expect to sufficiently solve the problems associated with the use of the purified aggregate mentioned above.

Korean Patent Registration No. 0317436

An object of the present invention is to provide an asphalt mixture that is environmentally friendly by using recycled aggregate, has the advantage of improving crack resistance, and can increase physical properties such as water resistance.

As a means for solving the above problems, the recycled aggregate medium temperature asphalt mixture of the present invention (hereinafter referred to as "the mixture of the present invention") is asphalt, new aggregate, recycled aggregate, filler, thermoplastic elastomer, polyethylene wax, sulfur powder, alkyl It is characterized in that it contains a pyrinium salt.

As an example, the first reinforcing fiber and the second reinforcing fiber composed of a material having a higher melting point than the first reinforcing fiber are further added.

As an example, the second reinforcing fiber is characterized in that the surface is coated with a coating layer made of seaweed powder.

As an example, the filler includes silicon dioxide and dolomite.

As an example, the dolomite is characterized in that the magnesium carbonate film is formed inside and outside by reacting with a gas containing carbon dioxide.

As an example, the filler is characterized in that it contains a mixture of inorganic waste sludge powder and sulfite that are by-products in the soda ash production process.

As described above, the mixture of the present invention is environmentally friendly by using recycled aggregate, has the advantage of improving crack resistance, and has the advantage of increasing physical properties such as watertightness.

Hereinafter, the configuration and operation of the present invention will be described in more detail based on the accompanying drawings. In describing the present invention, the terms or words used in the present specification and claims are based on the principle that the inventor can appropriately define the concept of the term in order to best describe his or her invention. It should be interpreted as meaning and concept consistent with the technical idea of

The mixture of the present invention is characterized in that it contains asphalt, novel aggregate, recycled aggregate, filler, thermoplastic elastomer, polyethylene wax, sulfur powder, and alkylpyrinium salt. That is, it is characterized in that the modified asphalt binder and aggregate containing additives such as asphalt and thermoplastic elastomer are included.

Preferably, the modified asphalt binder contains 1 to 8 parts by weight of thermoplastic elastomer, 0.01 to 1 parts by weight of polyethylene wax, 0.01 to 1 parts by weight of sulfur powder, and 0.01 to 1 part by weight of alkylpyrinium salts based on 100 parts by weight of asphalt. justifiable

The type of asphalt is not limited, but BRA (Buton Rock Asphalt) or TLA (Trinidad Lake Asphalt) may be applied, for example. BRA (Buton Rock Asphalt) or TLA (Trinidad Lake Asphalt) has a lower flexural strength coefficient than general asphalt, so when it is applied to steel deck, it is dependent on the behavior of the steel deck, and problems such as lifting of the joint surface are controlled.

The thermoplastic elastomer is a component that improves the viscosity at high temperature while enhancing elasticity at low temperature. Examples of the thermoplastic elastomer include styrene-butadiene rubber (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butadiene-styrene block copolymer (SEBS) ), styrene-isoprene-styrene block copolymer (SIS), etc.); Olefin copolymers (more specifically, ethylene-vinyl acetate copolymers (EVA), etc. may be applied.

The polyethylene wax functions as a medium-temperature additive, and lowers the temperature required for manufacturing and/or construction of the asphalt binder by about 20 to 40° C., thereby minimizing the emission of carbon dioxide and harmful substances. Preferably, the polyethylene wax has a melting point of 90 to 130° C., and a melt viscosity of about 130° C. of 80 to 300 cPs.

When the melting point of the polyethylene wax is less than 90 ℃, the strength of the asphalt may be weakened when mixed with the asphalt, and when the melting point exceeds 130 ℃, uniform dispersion is not made and non-uniform physical properties may be expressed. will be.

The sulfur powder is such that functions such as plastic deformation and fatigue crack resistance increase are expressed. As the sulfur powder, natural sulfur derived from mines may be used as a general sulfur element, but the amount of sulfur generated during desulfurization during the refining process of domestic oil refinery plants reaches about 1.5 million tons per year, and securing and usability of mass demand. It is preferable to use sulfur generated during the refining process of an oil refinery plant, an industrial by-product, in view of a situation where there is a limit to the increase.

The alkylpyrinium salt corresponds to a configuration for improving the adhesion between the asphalt binder and the aggregate.

On the other hand, new aggregate and recycled aggregate are applied to the mixture of the present invention.

In general, the quality or particle size of aggregate greatly affects the performance of the pavement, and physico-chemical properties differ depending on the production area. In general, coarse aggregate means the aggregate remaining in the 2.5 mm (No. 8) sieve, while fine aggregate is the aggregate remaining in the 0.08 mm (No. 200) sieve after passing through the 2.5 mm sieve.

means

Here, the coarse aggregate is crushed aggregate (crushed stone), crushed slag, crushed gravel, and the like, and preferably does not contain harmful substances such as clay, silt, and organic matter (refer to KS F 2357 standard). Fine aggregate is crushed sand (screenings) obtained by breaking rocks and gravel, natural sand, or a mixture thereof, and preferably does not contain harmful substances such as dust, clay, and organic matter (refer to KS F 2357 standard).

The recycled aggregate refers to an aggregate obtained by pulverizing pre-manufactured asphalt concrete, and the asphalt used in manufacturing the conventional asphalt concrete is attached, and generally 1.0 to 1.5 parts by weight of asphalt is attached based on 25 to 30 parts by weight of the recycled aggregate. .

Preferably, it is reasonable to mix 10 to 30 parts by weight of the recycled aggregate with respect to 100 parts by weight of the new aggregate.

In the present invention, the crack resistance is improved by further including reinforcing fibers in addition to the above composition. The present invention is characterized in that the first reinforcing fiber and the second reinforcing fiber of materials having different melting points are further added. That is, the first reinforcing fiber and the second reinforcing fiber composed of a material having a higher melting point than the first reinforcing fiber are further added.

Preferably, it is reasonable to mix 0.01 to 1 part by weight of the reinforcing fiber with respect to 100 parts by weight of the asphalt, and the first reinforcing fiber and the second reinforcing fiber are blended in a weight ratio of (4:6) to (6:4). justifiable

Here, the first reinforcing fiber and the second reinforcing fiber are selected from the group consisting of a cellulose fiber, a polyvinyl fiber, a nylon fiber, a polyethylene fiber, and a glass fiber, and are selected from two types having different melting points.

The first reinforcing fiber with a low melting point imparts adhesiveness to the binder by molecular bonding with the asphalt binder during the mixing process, and the second reinforcing fiber with a high melting point covers the aggregate in the form of bonding with the binder to form a bond between the aggregate and the binder and between the aggregate and the aggregate. It is to improve the shear strength and tensile strength of the asphalt mixture by greatly increasing the frictional force through the bridge effect.

On the other hand, polyethylene wax is added as a medium temperature additive to the mixture of the present invention as described above, but since the aggregate is heated at a lower temperature than that of the conventional heated asphalt mixture, there is a limit in removing moisture present in the aggregate in the process of preparing the asphalt mixture.

As a result, the asphalt mixture to which the medium temperature additive is added has lower moisture sensitivity than the heated asphalt mixture, so the cohesion and adhesion between the aggregate and the asphalt are weakened by the water flowing into the asphalt pavement. cause tally. This phenomenon, that is, the phenomenon that the asphalt flows down from the aggregate is called a "drain-down" phenomenon, and this phenomenon causes the problem of the aggregate to be detached from the asphalt after construction.

Accordingly, in the present invention, the second reinforcing fiber uses a modified reinforcing fiber coated with a coating layer of seaweed powder on the surface of the second reinforcing fiber. By expressing the viscosity upon contact with the second reinforcing fiber and the aggregate, the drain-down phenomenon is controlled. That is, the second reinforcing fiber coated with seaweed powder doubles the force holding the asphalt from the aggregate to control the drain-down phenomenon.

In addition, the seaweed powder applied to the second reinforcing fiber absorbs the moisture contained in the aggregate, thereby controlling the factors that decrease the water resistance of the binder due to the moisture.

Here, the type of seaweed powder is not limited, and for example, seaweed powder belonging to brown algae may be applied.

On the other hand, in the present invention, as mentioned above, in the case of the asphalt mixture to which polyethylene wax is added, moisture sensitivity is lowered than that of the heated asphalt mixture, and another embodiment is provided to solve the problem of lowering water resistance.

In this embodiment, an example in which silicon dioxide and dolomite are included in the filler is presented.

The silicon dioxide functions and serves to increase resistance to temperature change and humidity change by reducing thermal conductivity and reducing temperature deviation.

In addition to this, dolomite is included to impart water resistance to the paste, and the dolomite reacts with silicon dioxide to impart water resistance to water.

That is, a mixture of silicon dioxide and dolomite is added to the filler. Silicon dioxide improves the stability of the paste against changes in humidity. In addition, more dolomite is added so that the dolomite reacts with the silicon dioxide to give the paste water resistance to water. will do

As a result, even if sufficient moisture is not removed from the aggregate during the mixing process of the medium-temperature asphalt mixture, stability is obtained by silicon dioxide against humidity changes due to exposure to such moisture, and in addition to the moisture exposed by the reaction of silicon dioxide and dolomite This is to improve the water resistance of the paste.

The silicon dioxide and dolomite mixture is preferably mixed in a weight ratio of (6: 4) to (8: 2).

In addition to this, the present invention provides an example in which water resistance is doubled by mixing modified dolomite to improve reactivity with silicon dioxide.

In the present embodiment, the dolomite reacts with a gas containing carbon dioxide to include modified dolomite formed inside and outside the magnesium carbonate film.

Dolomite has pores inside and outside. Modified dolomite reacts dolomite particles with a gas containing carbon dioxide so that a film of magnesium carbonate is applied inside and outside dolomite. It is to supply a gas containing carbon dioxide to the furnace to form a film of magnesium carbonate on the surface and inside by diffusion.

As described above, the film is formed to generate magnesium carbonate (MgCO ₃ ) in the internal and external pores of the dolomite to double the reactivity with silicon dioxide, thereby improving water resistance as described above.

On the other hand, the mixture of the present invention includes recycled aggregate, and the recycled aggregate is used to regenerate waste asphalt. Since this cannot be completely reproduced, there may be problems such as a decrease in strength due to this point.

Accordingly, in the mixture of the present invention, the filler contains a mixture of inorganic waste sludge powder and sulfite that are by-products in the soda ash production process so that physical properties such as strength are supplemented.

The inorganic waste sludge powder produced by the soda ash production process is composed of sodium chloride and potassium carbonate as the main raw materials, and the inorganic waste sludge discharged from the plant producing soda ash (Na ₂ CO ₃ ) is sedimented and washed with water to be included in the sludge. It is manufactured by removing about 70% of the chlorine group (Cl ^- ), drying it at a predetermined temperature, and grinding it through a mesh of a predetermined size.

Such inorganic waste sludge powder is a material with a small specific gravity but high strength and does not expand even when heat is applied to improve the strength of asphalt. will be.

However, when only the inorganic waste sludge powder is used, the strength can be reinforced to some extent. However, the inorganic waste sludge powder contains a chlorine group (Cl ^- ) component that acts as an inhibitor of strength enhancement, so it can be used to reinforce asphalt strength. There are limits.

Accordingly, in the present invention, a mixture of inorganic waste sludge powder and sulfite is added to the filler. The sulfite promotes the decomposition of chlorine group (Cl ⁻ ) components from inorganic waste sludge powder by decomposition action and makes it immobilized into solid zinc chloride through hydrogen chloride, thereby inactivating chlorine group (Cl ⁻ ) as a strength inhibiting factor. .

Preferably, it is appropriate that the inorganic waste sludge powder and the sulfite are mixed in a weight ratio of (95:5) to (99:1).

Hereinafter, preferred embodiments of the present invention will be described by way of experimental examples.

<Production of Psalms>

After preheating while stirring the asphalt, 5 parts by weight of thermoplastic elastomer, 0.5 parts by weight of polyethylene wax, 0.5 parts by weight of sulfur powder, 0.5 parts by weight of alkylpyrinium salt, 0.1 parts by weight of polypropylene reinforcing fiber, 0.1 parts by weight of glass fiber based on 100 parts by weight of asphalt The modified asphalt binder is prepared by sequentially adding parts by weight, maintaining the stirring temperature at 140° C., and stirring for 30 minutes, and the modified asphalt is based on 100 parts by weight of a mixture of new aggregate, recycled aggregate (80: 20 by weight) and filler. An asphalt mixture was prepared by mixing 20 parts by weight of a binder while maintaining 140°C.

Here, in Example 1, glass fiber is added to the modified asphalt binder, and in Example 2, glass fiber coated with seaweed powder is added.

In addition, Example 3 is the same as Example 2, except that 20 parts by weight of a mixture of silicon dioxide and dolomite is mixed with 100 parts by weight of stone powder in the filler, and silicon dioxide and dolomite are blended in a weight ratio (6: 4), Example 4 was the same as Example 3 except that modified dolomite in which dolomite was reacted with a gas containing carbon dioxide to form a magnesium carbonate film inside and outside was used, Example 5 was the same as Example 2, except that 100 stone powder in the filler was used. 20 parts by weight of inorganic waste sludge powder was mixed with respect to parts by weight, Example 6 was the same as Example 5, except that 20 parts by weight of inorganic waste sludge powder and nitrite mixture (99 by weight ratio: 99: 1) was mixed.

The following experiment was performed with six specimens as shown above, and the results are shown in Table 1.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Water resistance (%) 61 66 74 78 67 66 Crack resistance (N) 19,760 19,810 19,910 19,970 19,920 19,960 Dynamic stability (times/mm) 920 970 965 970 980 990 Compressive strength (MPa, 28 days) 71 73 72 74 79 83

Water resistance (aggregate coverage after dynamic water immersion, %) was based on the EN-12697-11 Determination of the affinity between aggregate and bitumen test method. The Marshall stability and flow value test method of the asphalt mixture used was used as a standard, and the dynamic stability was measured by applying a force of 6.4kg/cm2 of ground pressure to a specimen of 300mm×300mm×50mm at 60℃ according to the wheel tracking test (KS F 2374) method. The number of reciprocations per dent depth (times/mm) was measured, and the compressive strength was measured using an asphalt compressive strength tester.

As shown in Table 1, it can be seen that Example 2 is superior to Example 1 in dynamic stability. It is considered that this is due to the control of the drain-down phenomenon.

In addition, it can be seen that Example 3 exhibits a superior effect than Example 2 in terms of water resistance, which is considered to be due to the fact that, as mentioned above, in the case of Example 3, a mixture of silicon dioxide and dolomite is further included in the filler, It can be seen that Example 4 exhibits a better effect in terms of water resistance than Example 3, which is believed to be due to the addition of modified dolomite to facilitate the reaction between silicon dioxide and dolomite as described above. .

In addition, it can be seen that Example 5 exhibits a superior effect than Example 2 in terms of compressive strength. It can be seen that Example 6 exhibits a more excellent effect in terms of compressive strength than Example 5, which is that nitrite is further contained in the inorganic waste sludge powder to inactivate chlorine groups (Cl ^- ) contained in the inorganic waste sludge powder. It is believed to be due to the In addition, it can be seen that Examples 5 and 6 are more advantageous than Example 2 in terms of dynamic stability.

Those skilled in the art from the above description will be able to see that various changes and modifications are possible without departing from the technical spirit of the present invention. Accordingly, the technical scope of the present invention is not limited to the content described in the detailed description of the specification, but should be defined by the claims.

Claims (6)

Including asphalt, new aggregate, recycled aggregate, filler, thermoplastic elastomer, polyethylene wax, sulfur powder, alkylpyrinium salt,
The filler is a recycled aggregate medium temperature asphalt mixture, characterized in that it contains a mixture of inorganic waste sludge powder and sulfite that are by-product in the soda ash production process.
The method of claim 1,
Recycled aggregate medium temperature asphalt mixture, characterized in that the first reinforcing fiber and the second reinforcing fiber composed of a material having a higher melting point than the first reinforcing fiber are further added.
The method of claim 1,
The second reinforcing fiber is a recycled aggregate medium temperature asphalt mixture, characterized in that the surface is coated with a coating layer of seaweed powder.
The method of claim 1,
Recycled aggregate medium temperature asphalt mixture, characterized in that the filler includes silicon dioxide and dolomite.
5. The method of claim 4,
The circulating aggregate medium temperature asphalt mixture, characterized in that the dolomite reacts with a gas containing carbon dioxide to form a film of magnesium carbonate inside and outside.
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