KR102753320B1 - Anti-freeze composition for asphalt concrete and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an anti-freezing additive for ascon and a manufacturing method thereof, wherein the anti-freezing additive comprises 70-90 wt% of sodium chloride, 3-10 wt% of a durability degradation inhibitor, and 0. The present invention relates to an anti-freezing additive and a manufacturing method thereof, wherein the anti-freezing additive comprises 1 to 3 wt% and 1 to 5 wt% of a dissolution inhibitor, prevents freezing on an asphalt road caused by a low temperature, and improves an anti-freezing effect by allowing the generated freezing to easily fall off to an external force applied from wheels of a vehicle or the like.

Description

{ANTI-FREEZE COMPOSITION FOR ASPHALT CONCRETE AND MANUFACTURING METHOD THEREOF}

The present invention relates to an anti-icing composition for asphalt concrete, which prevents freezing on an asphalt road caused by low temperatures and enhances the anti-icing effect by allowing the formed ice to easily fall off when subjected to external force from a vehicle's wheels, etc., and a method for manufacturing the same.

Ice on the road that occurs at low temperatures is a safety hazard for vehicles or pedestrians. Such ice on the road is defined as black ice. To easily remove the black ice, deicing agents such as calcium chloride or sodium chloride are sprayed on the road. Considering the cost of spraying and the impact on the environment, the use of such deicing agents has side effects, so an effective method that can replace it is needed.

Overseas, a technology is being developed to prevent freezing and slipping accidents by adding chlorides such as sodium chloride and calcium chloride, which can cause adverse effects such as vehicle corrosion, to asphalt, thereby making it easier for ice to fall off the road surface. In addition, in Korea, the Korea Expressway Corporation has set standards for anti-icing asphalt additives and is applying them to highway pavement.

These conventional technologies have been confirmed to be effective in preventing freezing on road surfaces. According to overseas research reports, the duration of the anti-icing effect on asphalt pavements to which anti-icing asphalt additives have been applied varies depending on the environment, but is reported to be approximately 4 to 7 years.

The main ingredient used for anti-icing in these additives is sodium chloride. In the case of calcium chloride, the decomposition is very high and the solubility is high, so if used, the asphalt pitch may be decomposed. Most additives are produced based on sodium chloride, and the sodium chloride surface is modified to prevent rapid dissolution. In this case, it is reported that the amount of sodium chloride dissolved on the asphalt pavement surface varies depending on the type of modifier. However, such sodium chloride modification treatment requires a lot of cost, and the process and equipment for treatment are also very expensive, so there is a problem in terms of production efficiency.

In general asphalt, the amount of additives used is about 5% of the total amount of asphalt, and in this case, they are used in place of fillers used in asphalt. These additives are known to prevent freezing as the anti-icing agent component is gradually dissolved during the period of asphalt use.

Korean Patent Publication No. 10-1780347 discloses a process for producing an anti-icing composition by mixing inorganic salt powder such as carbonate with organic acid, drying and calcining, then mixing it again with a porous body, dissolving it in a polar solvent containing a water-soluble polymer, and then drying. However, this process has the disadvantages of being too complex, having a very high production cost due to the calcination temperature of 750 to 1500°C, and requiring equipment for calcination.

In addition, Korean Patent Publication No. 10-2541279 proposes a technology for using ash, eggshell, mica, and coconut shell mixed with organic acid as an asphalt additive. However, organic acid has a disadvantage in that it is not effective in preventing freezing because the freezing point depression is not as great as that of salt, and therefore the amount used must be increased.

In addition, Korean Patent Publication No. 10-2161088 proposes a method of adding a road paving additive composition consisting of a liquid resin composed of silica nanoparticles and sucralose to concrete to make the concrete surface water-repellent and make ice fall off easily. However, there is a problem that it is difficult to implement an anti-icing effect in that it is difficult to maintain the surface water-repellent properties due to friction caused by tires on the road surface, and ice can easily stick to it if it is continuously compacted by the pressure applied from the wheels.

In addition, Korean Patent Publication No. 10-1971714 proposes a method of mixing sodium chloride and calcium chloride in water, impregnating the mixture into calcium carbonate, and drying it, and Korean Patent Publication No. 10-2592562 proposes a method of manufacturing the mixture by impregnating sodium chloride and calcium chloride into pulp, and coating the surface of the pulp by high-speed stirring. However, if calcium chloride is used as a component of an anti-icing composition, there is a problem that asphalt pitch may be damaged due to decomposition, which is disadvantageous for long-term use.

In addition, Korean Patent Publication No. 10-2600400 proposes an anti-icing composition containing at least one chloride selected from calcium chloride, sodium chloride, magnesium chloride, and aluminum chloride, and a mineral, but this composition is not economically feasible because it increases the production cost in the process, such as by including a drying step.

These conventional anti-icing agent compositions for asphalt have a period of about 4 to 7 years during which the anti-icing component completely dissolves and runs out over time when used. During this period, the asphalt shrinks by the weight of the anti-icing component, causing a change in volume, and the asphalt weakens to the extent of the volume loss, which has the problem of lowering the quality of the road surface.

The present invention has been made in consideration of the above-mentioned prior art, and its purpose is to provide an anti-icing composition and a method for producing the same, which exhibits an improved anti-icing effect by suppressing a decrease in the durability of a road surface constructed with asphalt, absorbing and removing heavy metals, and making it possible to easily remove ice formed by freezing on a road.

The anti-icing additive for asphalt of the present invention for solving the above-mentioned problems is characterized by comprising 82 to 90 wt% of sodium chloride, 3 to 10 wt% of a durability deterioration prevention agent, 0.1 to 3 wt% of a durability deterioration prevention auxiliary agent, and 1 to 5 wt% of a dissolution prevention agent.

At this time, the durability deterioration prevention agent may be one of calcium sulfoaluminate (CSA), type 1 ordinary portland cement, quicklime, slag powder, fly ash, or a mixture thereof.

Additionally, the durability degradation prevention auxiliary agent may be either illite or cordierite or a mixture thereof.

Additionally, the dissolution inhibitor may be one of zinc stearate and silicone powder or a mixture thereof.

In addition, it is preferable that the above-mentioned anti-icing additive for asphalt be added in a range of 3 to 8 wt% with respect to the entire asphalt.

The method for manufacturing an anti-icing additive for asphalt of the present invention is characterized by including the steps of adding sodium chloride to a mixer, adding a durability-decrease prevention agent to the mixer and mixing for 3 to 5 minutes, and adding a durability-decrease prevention auxiliary agent and a dissolution inhibitor to the mixer and mixing for 5 to 20 minutes.

The asphalt concrete anti-icing additive of the present invention can exhibit an effect of suppressing the phenomenon of reduction in the durability of a road surface by being added to asphalt concrete and used in asphalt construction.

In addition, by containing a durability deterioration prevention additive with heavy metal adsorption performance, it can exhibit the effect of adsorbing and removing heavy metals that may occur on the road surface.

In addition, it can exhibit an improved anti-icing effect by making it easy to remove ice formed by freezing on the road.

Figure 1 is a process diagram illustrating a process for manufacturing an anti-freezing additive of the present invention.

Hereinafter, the present invention will be described in more detail. The terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

The anti-icing additive for asphalt according to the present invention uses sodium chloride as an anti-icing agent, thereby resolving problems caused by potassium chloride, which was used as a conventional anti-icing agent.

Specifically, the above-mentioned anti-icing additive for asphalt is characterized by comprising 82 to 90 wt% of sodium chloride, 3 to 10 wt% of a durability deterioration prevention agent, 0.1 to 3 wt% of a durability deterioration prevention auxiliary agent, and 1 to 5 wt% of a dissolution inhibitor.

The above sodium chloride is a material with excellent freezing point depressing ability for anti-freezing, and has the advantage of being easily available and having relatively little impact on the environment. In addition, it is preferable that the moisture content of sodium chloride, an anti-freezing agent, does not exceed 1.0%. If the moisture content is too high, it must go through a drying process so as not to have a negative effect on the production of asphalt.

In addition, inorganic salts such as potassium chloride, calcium nitrate, and sodium nitrate, which can be used as anti-freezing agents for preventing freezing, and salts such as sodium acetate, potassium acetate, sodium formate, and potassium formate, are not only expensive, but also have lower freezing point depression ability than sodium chloride, making them undesirable in terms of effectiveness. In particular, polyvalent salts such as calcium chloride are not particularly desirable because their decomposition property is too high and may cause damage to asphalt concrete.

In addition, the anti-freeze additive of the present invention includes a durability degradation prevention agent so that durability can be maintained even when the anti-freeze agent is lost over time.

As the above durability deterioration prevention agent, any one of calcium sulfoaluminate (CSA), type 1 ordinary portland cement, quicklime, slag powder, fly ash, or a mixture thereof can be used.

The above CSA, ordinary portland cement, etc. components are hydraulic substances and absorb water molecules in the form of bound water when in contact with water. Therefore, they can suppress volume changes in asphalt by filling the space created after the anti-icing agent disappears. In addition, with a very stable chemical structure, they can help improve the durability of asphalt. In particular, among the hydraulic substances, CSA has 32 water molecules in the form of bound water when in contact with water, so it can function as a shrinkage compensator that eliminates volume changes. In addition, components such as slag fine powder and fly ash can obtain the effect of improving durability as pozzolanic substances.

In addition, the durability degradation prevention auxiliary agent may use one of illite and cordierite or a mixture thereof. In particular, it is preferable to use illite. Illite is a material for supplying moisture supplied from the outside to CSA, and is a porous material of the mica series with a chemical composition of K _0.8-0.9 (Al, Fe, Mg) ₂ (Si, Al) ₄ O ₁₀ (OH) _2. Depending on the porous characteristics of the surface, it can store moisture and has a heavy metal adsorption ability, so it can adsorb asphalt pitch or heavy metals in the air.

In addition, cordierite, like illite, has porous characteristics and a coefficient of thermal expansion of 1.7 to 2.2×10 ^-6 /K, so it is not only effective in adsorbing asphalt pitch or heavy metals in the air, but can also have the effect of improving heat resistance.

It is preferable that the above durability deterioration prevention auxiliary agent have a particle size of 75㎛ or less. This is because if the particle size is too large, it may have a negative effect on asphalt.

In addition, a dissolution inhibitor is added to prevent the sodium chloride from dissolving quickly. As the dissolution inhibitor, either one of zinc stearate and silicone (silicone resin) powder or a mixture thereof can be used. The zinc stearate and silicone powder are super-hydrophobic substances having a surface contact angle of 130° or more, and exhibit excellent water repellency, so that even when used in small quantities, they exhibit the characteristic of preventing rapid dissolution of salt. In the case of other fatty acid salts similar to the zinc stearate, the water contact angle is less than 130°, which is disadvantageous.

As described above, the anti-icing additive for asphalt of the present invention comprises 82 to 90 wt% of sodium chloride, 3 to 10 wt% of a durability-decrease prevention agent, 0.1 to 3 wt% of a durability-decrease prevention auxiliary agent, and 1 to 5 wt% of a dissolution inhibitor, and the content range is optimized in consideration of changes in physical properties according to each component.

If the anti-freezing additive for the above asphalt concrete contains too little of the anti-freezing agent, the anti-freezing effect may be insufficient or the period of use as an additive may be shortened. If the anti-freezing additive contains too much, the proportion of other components in the entire composition may be reduced, shortening the period of anti-freezing.

In addition, if the durability-deterioration inhibitor is contained too little, the durability may be reduced, and if it is contained too much, the durability of the asphalt may be reduced due to an increase in the number of bonds.

In addition, if the content of the durability-lowering prevention additive is too low, the durability-lowering agent may not work smoothly, and if it is contained too much, the economic efficiency may be poor.

It is preferable to use the above durability deterioration prevention auxiliary agent after forming a slurry by adding 2 to 10 times the total mass used. When forming a slurry, if the amount of water is too small, a slurry with an appropriate viscosity is not formed, and if it is too large, the amount of water is too large and a drying process must be performed. In addition, the water constituting the slurry can enable the dissolution inhibitor and the durability deterioration prevention agent to bind well to the surface of the anti-icing agent.

In addition, if the amount of the anti-freezing agent used is too small, the sodium chloride may easily melt, shortening the period during which the anti-freezing effect is exhibited, and even if it is contained in excess of the above range, the anti-freezing performance does not increase any further, which is not economical.

In addition, the process for manufacturing the anti-icing additive for asphalt is as follows.

A ribbon mixer can be used as a mixer. In the ribbon mixer, first, sodium chloride is added, then a durability deterioration prevention agent is added, and stirred for 3 to 5 minutes to make a homogeneous phase. A dissolution prevention agent is added thereto, and mixed evenly for 3 to 5 minutes. A durability deterioration prevention auxiliary agent is added thereto, and by mixing for more than 5 minutes, the target bonding prevention composition for asphalt is completed. If the process order is changed in the above process, a certain performance deterioration may occur, so it is preferable to perform the process according to the above order. In addition, if the mixing time is shorter than 3 minutes, uniform mixing may not be achieved, and if it is longer than 5 minutes, recombination may occur, which is not preferable. In addition, if the mixing after adding the durability deterioration prevention auxiliary agent is shorter than 5 minutes, there is a concern that uniform mixing may not be achieved.

The anti-icing additive of the present invention can prevent the problem of deterioration of the durability of asphalt by utilizing hydraulic properties, and exhibits the effect of adsorbing heavy metals on the road. In addition, it can easily remove or suppress ice that occurs on asphalt pavement.

The properties of the above anti-icing additives were evaluated based on the standards for anti-icing agents of the Korea Expressway Corporation. The standards for anti-icing agents of the Korea Expressway Corporation include a method of observing the change in dissolution rate in water over time for 1 hour and 24 hours and a method of comparing the adhesion by mixing it with bitumen, which is a binder of asphalt, in a 1:1 ratio and attaching ice. In addition, the durability of asphalt concrete can be evaluated by using 3 to 5% of the total weight of asphalt concrete as a substitute for asphalt filler and comparing the dynamic stability values of asphalt concrete to observe the decrease in durability.

Table 1 shows the composition ratio of the anti-freezing additives of the present invention (Examples 1 to 3). For comparison, commercially available sodium chloride-based anti-freezing additives, ZTA-MS (particles) (Comparative Example 1) and ZTA-MS (powder) (Comparative Example 2), were evaluated. The unit in Table 1 is weight %.

Name of substance Example 1 Example 2 Example 3 NaCl 82 86.7 82 CSA 10 8 7 quicklime 0 0 3 Illite 3 0.3 3 Zinc stearate 5 5 0 Silicone Powder 0 0 5 total 100 100 100

To evaluate the anti-icing additive, the change in solubility in water over time (1 hour and 24 hours), the content of insoluble matter, and the adhesion strength of ice after mixing with bitumen were measured.

The change in dissolution rate over time is to observe the dissolution rate, and to observe the solubility of the additive at 1 hour and 24 hours to confirm that it dissolves from the asphalt packaging to the surface over a long period of time. For each 1 liter of material, 500 cc of distilled water is put into two beakers, and 10 g of the anti-freezing additive is evenly spread on the surface of the distilled water. After 1 hour and 24 hours, it is filtered through a ceramic Buchner funnel with an 11 ㎛ filter, and dried at a temperature of 100℃ until there is no change in weight, and the ratio of the mass decreased at this time is defined as the dissolution rate at 1 hour and 24 hours. To test the total dissolved matter content, 1 g of material and 10 g of distilled water are placed in a mortar and pestle, crushed with a pestle for 30 minutes, filtered through a filter paper, and the dissolved matter remaining on the filter paper is sufficiently washed by additional distilled water, and 1% silver nitrate is dropped into the water that has passed through the filter paper, and the test is complete if no white precipitate occurs. The mass is measured at this time, and the dissolved matter content is obtained by multiplying the amount reduced from 1 g by 100.

To measure the ice adhesion strength, mix the above materials in a mass ratio of 1:1 with bitumen heated to about 150℃, cool completely at room temperature, place a cotton towel (20 counts of cotton yarn) that has absorbed water on the surface, install a jig, and measure the adhesion strength after 3 hours in a low-temperature chamber at -6℃. At this time, the pulling speed is 0.035 MPa per second and the value is used as the ice adhesion strength.

The test results are shown in Table 2. In Table 2, the dynamic stability test was performed with 4% of additives applied to the weight of 10 mm of asphalt mixture.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Content of dissolved components (%) 81.0 84.1 82.3 99.2 94.0 1 hour change rate (%) 35.0 38.8 32.5 89.2 69.4 24-hour change rate (%) 64.9 59.38 49.3 98.0 99.4 Ice adhesion strength (Mpa) 0.01 0.01 0.01 0.1 0.1 Dynamic stability (times/mm) ^※ 3,400 3,340 3,890 2,830 2,360

The Korea Expressway Corporation has set and is using the standard values for anti-icing additives, and stipulates that the content of soluble components is 76 to 86%, the dissolution rate after 1 hour is 55% or less, and the dissolution rate after 24 hours is 75% or less. In addition, the adhesion strength of ice is 0.1 MPa or less. As can be seen from the results above, the content ratios of soluble components in the cases of Examples 1 to 3 were 81.0%, 84.1%, and 83.3%, which all satisfy the standard values, and in the case of the change rates over 1 hour and 24 hours, Examples 1 to 3 were 35.0%, 38.8%, and 32.5%, and 64.9%, 59.38%, and 49.3%, respectively. On the other hand, in the case of Comparative Examples 1 and 2, the content ratio of dissolved components was 99.2% and 94.0%, respectively, which exceeded the standard, and in the case of the change rates over 1 hour and 24 hours, they were 89.2%, 69.4% in Comparative Examples 1 and 2 and 98.0% and 99.4%, which were all unsatisfactory. This means that the lifespan of the anti-icing agent is very short because the lifespan of the additive is very short, making it difficult to use for a long period of time, and that it may not be usable for several months or the following winter if it rains a lot in the summer. However, the ice adhesion strength was confirmed to be a value that satisfied the standard, so it was determined that it would be effective immediately after the asphalt concrete was laid. In particular, the dynamic stability in SMA (Stone Mastic Asphalt), which is a durability index, was 3,400 times/mm, 3,340 times/mm, and 3,890 times/mm for Examples 1 to 3, whereas it was 2,830 times/mm for Comparative Example 1 and 2,360 times/mm for Comparative Example 2, showing significantly worse durability. This suggests that durability may deteriorate when the anti-icing agent component dissolves and escapes. Therefore, it was confirmed that the anti-icing additive of the present invention can maintain durability by compensating for the escape of the anti-icing agent.

In addition, the heavy metal adsorption capacity of illite, which is used as an additive to prevent durability degradation, was measured and compared by measuring the amount of heavy metals released from the asphalt mixture after use using AAS (atomic absorption spectroscopy). Atomic absorption spectroscopy is a method for detecting trace elements, and 10 g of the mixture was dissolved in 100 g of trichloroethylene and then evaporated before measurement.

Content (ppm) Element name Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Pb Not detected Not detected Not detected Not detected Not detected Ni 18 15 23 64 62 Hg Not detected Not detected Not detected Not detected Not detected Cr 0.1 0.1 0.1 0.3 0.3

Table 3 shows the results of measuring the heavy metal content in the additives of the examples and comparative examples. As can be seen in the results, in the case of Examples 1 to 3 where illite was used, Ni was measured as 18, 15, and 23 ppm and 0.1, 0.1, and 0.1 ppm, whereas in the case of Comparative Examples 1 and 2, it was measured as 64 and 62 ppm and 0.3, 0.3 ppm, confirming that the heavy metal adsorption property of the anti-icing additive of the present invention is improved by the added illite.

The rights of the present invention are not limited to the embodiments described above, but are defined by what is described in the claims, and it is obvious that a person skilled in the art in the field of the present invention can make various modifications and adaptations within the scope of the rights described in the claims.

Claims (6)

It is composed of 82 to 90 wt% of sodium chloride, 3 to 10 wt% of a durability deterioration inhibitor, 0.1 to 3 wt% of a durability deterioration prevention auxiliary agent, and 1 to 5 wt% of a dissolution inhibitor.
An anti-icing additive for asphalt, characterized in that the durability deterioration prevention agent is calcium sulfoaluminate (CSA) or a mixture of calcium sulfoaluminate and quicklime.
delete In claim 1,
An anti-icing additive for asphalt, characterized in that the above durability degradation prevention auxiliary agent is either illite or cordierite or a mixture thereof.
In claim 1,
An anti-freezing additive for asphalt, characterized in that the above-mentioned anti-dissolution agent is one of zinc stearate and silicone powder or a mixture thereof.
In claim 1,
An anti-icing additive for asphalt, characterized in that the above-mentioned anti-icing additive for asphalt is added in a range of 3 to 8 wt% with respect to the entire asphalt.
A method for manufacturing an anti-icing additive for asphalt according to claim 1,
Step of adding sodium chloride into the mixer;
A step of adding a durability deterioration prevention agent to the above mixer and mixing for 3 to 5 minutes;
A step of adding a durability deterioration prevention auxiliary agent and a dissolution inhibitor to the above mixer and mixing for 5 to 20 minutes;
A method for producing an anti-icing additive for asphalt, characterized in that it includes: