JPH0881672A - Antifreezing agent for road pavement material - Google Patents

Abstract

PURPOSE: To obtain an antifreezing agent for a draining or a grooving pavement material, provide a method for preventing the pavement material from freezing using the antifreezing agent and produce the pavement material prevented from the freezing. CONSTITUTION: This antifreezing agent for a draining or a grooving pavement material comprises an acidic aqueous solution of chitosan, urea and a chitosan gelling agent. This method for preventing the pavement material from freezing is to scatter an ungelatinized solution of an acidic aqueous solution containing chitosan, urea and a chitosan gelling agent on the surface of the pavement material, make the solution flow into the interior of voids or grooves of the pavement material and gelatinize the solution in the method for preventing the draining or grooving pavement material from the freezing. Furthermore, this pavement material prevented from the freezing is produced by occluding a chitosan gel containing the urea in the interior of the voids of the draining pavement material or occluding the chitosan gel containing the urea into the interior of the grooves of the grooving pavement material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antifreezing agent for a road drainage pavement or a grooving pavement, a method for preventing the pavement from freezing, and a pavement protected from freezing.

[0002]

2. Description of the Prior Art Drainage pavements for roads using an open-grain size asphalt mixture as the surface layer, because of its high porosity, drain rainwater promptly, so when a vehicle is traveling, prevent hydroplaning during rainfall. It has the advantages of preventing water splash, improving visibility at night rainfall, and absorbing traffic noise. Therefore, such a drainage pavement is drawing attention as a functional pavement, and the number of constructions thereof is increasing year by year. On the other hand, grooving pavements having the same function as drainage pavements have also been adopted year by year. This method is 6 mm wide at intervals of about 20 mm in the transverse direction of the pavement surface,
A groove having a depth of about 6 mm is cut to improve drainage performance on the road surface. However, during the winter months in snowy and cold regions, problems occur with the function of these pavements. That is, in the drainage pavement, the interior of the voids of the pavement is filled with snow and ice, the drainage of water on the surface of which snow and ice are melted becomes poor, the water freezes at night, and the road surface becomes slippery. Or, there is a problem that the water that has entered the voids freezes and the pavement is destroyed. On the other hand, in the grooving pavement, the groove formed in the pavement is filled with snow or ice, the drainage function cannot be exerted, and the road surface becomes slippery with snow or ice.

As a means for solving such a problem, sodium chloride, calcium chloride,
A method of spraying snow-melting agents such as urea and calcium acetate / magnesium to melt the snow and ice embedded in the voids of drainage pavements and in the grooves of pavements of grooving pavements. and so on. However, this method is effective for a while after spraying the snow-melting agent, but as the melting action of snow and ice progresses, the snow-melting agent diluted with water from the voids of the drainage pavement or the grooves of the grooving pavement. However, it has a drawback that it easily flows out and the effect is not persistent. Therefore, it is necessary to frequently spray the snow-melting agent, and as a result, not only the economical demerits associated with the increase in the spraying labor and the increase in the amount of the snow-melting agent sprayed, but also the water pollution and the corrosion of vehicles and bridges due to the large amount of spraying. It also causes environmental problems such as effects on plants.

As a method for solving such a problem, a method disclosed in JP-A-63-236802 has been proposed. In this method, urea is heated and melted at a melting point of 135 ° C. or higher to form a liquid, which is sprayed on the surface of the drainage pavement, permeated into the voids, and solidified by natural cooling. However, according to this method, when snow or ice comes into contact with urea, the snow or ice is easily melted, but urea itself is also dissolved at a high concentration in the melted water. At this time, since the pavement is drainable, it has a drawback that dissolved urea also flows out. Therefore,
In this method, the initial effect is expected, but the sustainability of the effect is not always sufficient.

[0005]

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide an antifreezing agent for drainage pavements and grooving pavements, a method for antifreezing those pavements using the same, and those antifreeze pavements. Let's take that issue.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a solution of a chitosan acid aqueous solution in which urea as a freezing agent and a chitosan gelling agent are dissolved is gelled. Before pouring the reaction, the pavement is effectively and sustainably frozen when it is poured into the voids of the drainage pavement or the groove of the grooving pavement while it is being stored and gelated. They have found that they can be prevented, and have completed the present invention.

That is, according to the present invention, there is provided an antifreezing agent for drainage pavement or grooving pavement, which comprises an acidic aqueous solution of chitosan, urea and a chitosan gelling agent. Further, according to the present invention, in a method for preventing the drainage pavement or grooving pavement from freezing, a non-gelled solution of an acidic aqueous solution containing chitosan, urea and a chitosan gelling agent is sprayed on the surface of the pavement, There is provided a method for preventing freezing of a pavement, which is characterized by flowing into a void or a groove of the pavement to cause gelation. Further, according to the present invention, there is provided a pavement protected from freezing, which is obtained by occluding chitosan gel containing urea inside the voids of the drainage pavement. Further, according to the present invention, there is provided a pavement which is protected from freezing by occluding chitosan gel containing urea inside the groove of the grooving pavement.

In the antifreezing agent of the present invention, the acidic aqueous solution of chitosan can be obtained by adding chitosan to the acidic aqueous solution and dissolving it. Examples of the acidic aqueous solution include aqueous solutions containing an organic acid such as acetic acid, formic acid and lactic acid, and an acidic substance such as inorganic acid such as hydrochloric acid and nitric acid. The concentration of the acidic substance in the aqueous solution is 0.5 to 5% by weight, preferably 0.7 to 3% by weight. The amount of chitosan added to the acidic aqueous solution is such that the concentration of chitosan in the acidic aqueous solution is 0.5 to 5% by weight, preferably 0.7 to 3% by weight. Chitosan is a hydrolyzate of chitin that is often found in crustaceans such as crabs and shrimps, and insects such as cicadas and beetles. Glucosamine has β-1,
It is a 4-linked natural polysaccharide. The amount of urea added to the acidic aqueous solution is 10 to 60 parts by weight, preferably 25 to 45 parts by weight, based on 100 parts by weight of the acidic aqueous solution containing chitosan. The amount of the chitosan gelling agent added to the acidic aqueous solution is 3 to 33 parts by weight, preferably 6 to 24 parts by weight, relative to 1 part by weight of chitosan. As the chitosan gelling agent, any agent may be used so long as it can react with chitosan to crosslink or insolubilize chitosan to cause gelation, and various conventionally known agents are used. Aldehyde compounds such as acetaldehyde, formaldehyde, glutaraldehyde, and propionaldehyde are generally used as such compounds.

The antifreezing agent of the present invention comprises an acidic aqueous solution, chitosan, urea and a chitosan gelling agent. In this case, it is preferable to dissolve chitosan and urea in the acidic aqueous solution in advance to form a chitosan gel. The agent is added at the work site immediately before freezing the road pavement.
Of course, it can also be obtained by adding chitosan, urea and chitosan gel to an acidic aqueous solution at the work site.

The antifreezing agent of the present invention starts the gelling (polymerization) reaction of chitosan by the addition of the chitosan gelling agent, but the solution is fluid for a certain period of time after the addition of the chitosan gelling agent. However, it can be sprayed by a spray nozzle. After addition of chitosan gelling agent, after a certain period of time,
The gelation reaction of chitosan is completed, and the whole solution becomes a semi-solid gelled product. The time until the solution containing the chitosan gelling agent becomes a gelled product (gelling reaction time) can be changed depending on the concentration of chitosan in the solution and the amount of the chitosan gelling agent added, etc. Is 5 minutes to 1 hour. Within such gelling reaction time, the solution has fluidity and can be sprayed. The desired gelling reaction time is appropriately selected according to the actual spraying work time.

The amount of the antifreezing agent applied to the road pavement varies depending on the type of pavement, weather conditions, etc., but a small amount of 200 to 500 ml per 1 m ² is usually sufficient. The spraying method is not particularly limited, and it can be performed using a liquid spraying device having a spray nozzle. In short, any spraying method may be used as long as it can uniformly spray the antifreezing agent on the surface of the pavement. The solution-type antifreezing agent sprayed on the pavement surface permeates into the voids of the drainage pavement and the grooves of the grooving pavement, gels inside, and is occluded (adhered) to the inner surfaces of the voids and grooves. . The gelled substance occluded in the inner surface of the void or groove of the pavement is made of chitosan gel containing urea therein, and the urea is protected by the chitosan gel. Therefore, snow and ice,
Even when it comes into contact with water, the elution of urea is prevented, and its antifreezing effect lasts for a long time.

In the drainage pavement or grooving pavement containing the antifreezing agent of the present invention, even if snow accumulates on the surface of the pavement, the snow melts at the point of contact with the surface of the pavement and the water freezes. Drains easily through voids and ditches in the pavement without. Further, since snow and ice do not solidify on the surface of the pavement, snow and ice can be easily peeled off by the passage of a vehicle, and the pavement surface can be easily exposed.

[0013]

EXAMPLES Next, the present invention will be described in more detail by way of examples. (1) Preparation of antifreezing agent and gelation reaction time In preparing an acidic aqueous solution of chitosan, the chitosan concentration and the acid concentration were adjusted to be the same. First, chitosan powder was added to and dissolved in a 0.7 wt% aqueous solution of acetic acid in an amount to give a chitosan concentration of 0.7 wt%. Industrial urea was added to this aqueous solution to prepare a urea concentration of 30 wt%. An amount of glutaraldehyde having a concentration of 10% was added to the chitosan-urea aqueous solution, and the time until the solution gelled was measured. In the same manner as above, a chitosan-urea aqueous solution having different chitosan concentrations was prepared, and the time from the addition of glutaraldehyde to the gelation of the solution into a semi-solid state was measured. The results are shown in Table 1.

[0014]

[Table 1] From the above results, the higher the ratio of chitosan to aldehyde, the shorter the gelling time.

(2) Storage of antifreezing agent and antifreezing effect (Preparation of test specimen of drainage pavement) Preparation of drainage pavement is carried out by Marshall stability test, which is a general method for examining the characteristics of asphalt mixture. The process was carried out according to the method for producing the specimen to be used. Table 2 shows the mixing ratio of the aggregate and the asphalt per one test body.

[0016]

[Table 2] The test body of the drainage pavement was manufactured according to the following procedure. First, add each of the aggregates listed in Table 2 to a mixer,
Heat and mix to 180 ° C. Next, asphalt preheated to 160 ° C. is added, and further mixed by heating at 188 ° C. The asphalt mixture thus obtained was placed in a cylinder for producing a Marshall test specimen, and 170
The front and back were compacted at 0 ° C., naturally cooled, and then removed from the cylinder to obtain a test body having a diameter of 100 mm and a thickness of 70 mm. The porosity of the test body of this drainage pavement was about 20 vol%.

(Anti-freezing test) The bottom and side surfaces of the test piece prepared as described above are sealed with a resin film, and the anti-freezing agents A to D shown in Table 1 are poured from the surface of the test piece to form the inside of the void. It was made to gel and occluded. After the gel was sufficiently gelled, water was poured from the surface of the test body to fill the voids. For comparison, water was poured from the surface of the test body that did not contain the antifreezing agent, and the voids were filled with water. These test bodies are -5 ℃
I left it in the refrigerator for 24 hours. After that, these test bodies are tumbled and held for 30 minutes to collect water that has not frozen,
The antifreezing effect was investigated. Table 3 shows the results.

[0018]

[Table 3]

Water was frozen in the voids of the test bodies that did not occlude the antifreezing agent, and no water was recovered. However, in all the other test bodies, the water did not freeze inside the voids. Water was injected again into the test bodies A and B having a relatively large storage amount of the antifreezing agent, and the same test was repeated. Table 4 shows the results.

[0020]

[Table 4]

From the above results, the antifreeze agent occluded is
It did not flow easily, and the sustainability of the effect was confirmed.

Claims (5)

[Claims] 1. An antifreezing agent for drainage pavement or grooving pavement, which comprises an acidic aqueous solution of chitosan, urea and a chitosan gelling agent. 2. The antifreezing agent for pavements according to claim 1, wherein the chitosan gelling agent is an aldehyde compound. 3. A method for preventing freezing of a drainage pavement or a grooving pavement, wherein a non-gelled solution of an acidic aqueous solution containing chitosan, urea and a chitosan gelling agent is sprayed on the surface of the pavement, A method of preventing freezing of a pavement, which comprises causing gelation by flowing into voids or grooves. 4. An anti-freezing pavement in which a chitosan gel containing urea is occluded inside the voids of the drainage pavement. 5. A pavement protected from freezing, which is obtained by occluding chitosan gel containing urea inside the groove of the grooving pavement.