JPS5846229B2 - Bituminous mixture used in rolled asphalt pavement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bituminous mixture containing nickel slag used when constructing rolled asphalt pavement for road pavement.

Rolled asphalt pavement uses asphalt mortar made of sand, stone powder, and asphalt (bituminous) as its base material.
A mixture of a certain amount of relatively single-grained crushed stone is mixed into the paving layer, and crushed stone coated with asphalt (called chipping material) is sprinkled on top of the mixture to give it a finishing touch, maintaining watertightness while maintaining slip resistance. This is a paving method that requires high quality, durability, and wear resistance.

The ``Asphalt Pavement Guidelines'' published by the Japan Road Association contains standard mix examples for rolled asphalt mixtures, but does not provide clear means for mix design, so when implementing it, it is necessary to Standard B5
-594/1973.

This B5-594 has a weight ratio of sand to stone powder of asphalt mixture used for rolled asphalt pavement.
It is set as 1 against stone dust.

However, as long as sand collected in Japan is used, a mixture with a weight ratio of 6:1 to stone powder has low stability and easily flows, and cannot be put to practical use. Modified asphalt with a 3:1 weight ratio of stone powder and Trinidad Lake asphalt added as a binder is used to improve watertightness and stability, but the process is complicated and difficult to manufacture. Currently, it is not possible to obtain a material that is satisfactory in terms of slip resistance, durability, and abrasion resistance, while being accompanied by an increase in cost.

In view of the above-mentioned reality, the present invention aims to obtain good results by using nickel slag instead of sand in the bituminous mixture used for rolled asphalt pavement, and in order to achieve the above object. The main invention is a bituminous mixture made by mixing nickel slag and stone powder in a predetermined composition ratio to form fine aggregate, and the remainder is asphalt (bituminous) and crushed stone in a certain amount, and furthermore, the bituminous mixture is The object of the present invention is to also disclose an invention of a bituminous mixture obtained by mixing an olefinic copolymer with a olefinic copolymer.

The bituminous mixture used in rolled asphalt pavement consists of sand, stone dust, asphalt (bituminous), and relatively single-grained crushed stone, and the stability of the mixture depends largely on the interlocking of the sand. The hardness, shape, and material have a very strong influence.

The sand in England, where rolled asphalt pavement was developed, is rich in ridges because it was created by glaciers scraping away rocks, while the sand in Japan is spherical because it is abraded by river water. Therefore, the particle size and shape are greatly different.

On the other hand, the nickel slag adopted in the present invention is made by pulverizing the slag produced when refining ferronickel from nickel oxide ore by the J Lefprene method using a ball mill, and contains enstite (MgO, 5i02) and holsterite (2Mg0).・Si02) is an aggregate with extremely small fluctuations in quality, mainly composed of glass and minerals, is hard enough to have a Mohs hardness of 7 or more, and microscopically has many ridges and is semi-molten. Since it is a crystal aggregate with different hardness because it is formed while being stirred in a state of It is filled with a filler bitumen mixture, which improves watertightness and exhibits high stability with respect to various physical properties required of the mixture.

In addition, as mentioned above, this nickel slag is a crystal aggregate with many edge angles and different hardness, so it exhibits high slip resistance and remains smooth even when subjected to impact from automobile driving or abrasive action. Because the paved surface wears out in stages and always maintains minute irregularities, the paved surface maintains sharp ridge angles, and there is no decline in slip resistance.By press-fitting chip material into the surface, slip resistance Durability and abrasion resistance can be strengthened.

Table 1 shows the main physical properties of nickel slag.

Next, the test construction of the bituminous mixture employed in the present invention will be described.

In the mix design, the weight composition ratio of nickel slag and stone powder was set to 6:1 (Examples I, n) and 9:1 (Examples IN, IV).
, V), and conforms to the limit conditions that were previously considered impossible when using Japanese sand. Test construction was conducted for two types.

Regarding the weight composition ratio of nickel slag and stone powder mentioned above, it is clear from experience that the physical properties of the asphalt mixture become stronger when the composition ratio of stone powder is increased. However, as shown in the above example using conventional sand, the weight composition ratio of nickel slag and stone powder was set to 3. It is easy to understand that there is no problem with tubules even if the ratio is 1:1.

The bituminous substances used as binders include straight asphalt, semi-blown asphalt, blown asphalt, modified asphalt based on these, cantopack asphalt, and even tar, etc. These bituminous compositions have high stability, durability, It may be used if it is mixed and applied with special care to maintain wear resistance.

Examples I, n, I, IV, and V will be explained below, and at the same time, the case where Japanese sand was conventionally used will be listed as a comparative example.

Examples I, II *
- The above-mentioned rolled asphalt pavement was test constructed using a mixture in which the weight composition ratio of nickel slag and stone powder was 6:1 as shown in Table 2.

In addition, in order to determine the effect of chip material made of coarse bone material during construction, dynamic stability (D, S times/mm) and porta pull were determined by wheel tracking tests (wheel running tests) when chip material was not press-fitted and when chip material was press-fitted. The skid resistance value was measured using a skid resistance tester.

The results are shown in Table-3. In the above, the wheel tracking test was conducted at a test temperature of 60℃, and the ground pressure was 5.5kg.
/(, f.

The chip material was pre-coated crushed stone (20 to 13 m2) and was spread and press-fitted at 10 kg per square meter.

Example 1. IV, V Table-4 shows the compounding ratio when the weight composition ratio of nickel slag and stone powder is 9:1, and Table-5 shows the results of test construction.

Note that the test method and result items are the same as in Examples I and II.

As can be seen from the characteristic values in Table 3, when the weight composition ratio of nickel slag and stone powder is 6:1, when the penetration is 40-60 and when 60-80 is used, the dynamic stability is as follows: ~80 gives a slightly smaller value, but has sufficient stability and wear resistance to withstand heavy traffic roads.

Furthermore, from the results in Table 5, even if the weight composition ratio of nickel slag and stone powder is 9:1, it shows a value that can withstand use in areas with heavy traffic.

In addition, in Example ■, the olefin copolymer described later was used as *C
It has been found that by adding an appropriate amount, durability can be increased without changing the amount of asphalt, and further, physical properties can be greatly improved by press-fitting the chip material.

In addition, Table 6 shows the results of an investigation of changes in slip resistance over time between the conventional rolled asphalt using sand and the rolled asphalt pavement containing nickel slag of the present invention.

The test used a portable skid resistance tester.

When conventional sand was used, the expected value of 60 was not reached from the beginning, but the value decreased over time.

This shows that when nickel slag is used, a high resistance value is maintained over a long period of time.

Next, test construction was carried out using conventional sand and varying the weight composition ratio of sand and stone powder for bituminous mixtures used in rolled asphalt pavement, and the results are described as a comparative example. According to the above, the stability is set at 500 kg or more except in special cases, but Comparative Examples 1 and 2
, 3, and 4, the stability did not reach 500 kg.

Only Comparative Example 5 satisfies the stability, but when the dynamic stability of this is determined, it is 222 times/clothing, and durability is difficult to expect.

In addition, the olefin copolymer has an affinity with asphalt and can melt and flow at a temperature below the heating mixing temperature of the asphalt mixture, such as ethylene vinegar picopolymer,
One or several types of copolymers selected from the group of ethylene/ethyl acrylate copolymer, ethylene/methacrylate copolymer, and ethylene(meth)acrylic acid copolymer are used, and the shape of these copolymers is powdery,
It is desirable to have a uniform surface area in the form of fine particles, fragments, or flakes.

The effect of using this olefin copolymer is clear from the above-mentioned Example (2), but it can also be proven from the results of wheel tracking tests and labeling tests performed on layered asphalt concrete.

Table 8 shows the results. In the example described above, nickel slag and stone powder are mixed in a preset arbitrary composition ratio to form fine aggregate, and the remainder is mixed with a certain amount of bituminous material and crushed stone to form a bituminous mixture. However, it has been confirmed that a practically satisfactory mixture can be obtained even when sand is mixed into the fine aggregate at a weight ratio of less than 50% and applied to rolled asphalt pavement.

Therefore, the present invention is not limited only to nickel slag, but it is also within the scope of the invention to add some sand.

As explained in detail above, the present invention provides a bituminous mixture in which nickel slag, which is a nickel slag refined by the Kurzprene process, is mixed as a fine aggregate and is suitable for rolled asphalt pavement, and the asphalt used is also easily available. The normally used penetration of 60 to 80 is sufficient, and therefore there is no need to mechanically improve the asphalt plant that has been used up until now, and there is no need to clean or add asphalt keradors. Nickel slag has the advantage of realizing a bituminous mixture that satisfies the properties required for road pavement, such as slip resistance, durability, abrasion resistance, and other properties. Together with these characteristics, it provides a bituminous mixture with extremely high usability.

Claims (1)

[Scope of Claims] 1. Nickel slag and stone powder produced when refining ferronickel from nickel oxide ore by the Kurzprene method are mixed in a weight ratio of 3:3 of nickel slag to 1:1 to 9:1 of stone powder to form fine bones. A bituminous mixture used for rolled asphalt pavement, characterized in that the remainder is mixed with a certain amount of bituminous material and crushed stone. 2. The bituminous mixture used for rolled asphalt pavement according to claim 1, wherein less than 501% by weight of sand is mixed into the slag. 3 Nickel slag and stone powder produced when refining ferronickel from nickel oxide ore by the Krunpuren method are mixed to form a fine aggregate in a weight ratio of 3 parts nickel slag to 1 part to 9 parts stone powder, and the remainder is bitumen. It is characterized in that it is made by heating and kneading an appropriate amount of an olefin copolymer that has an affinity for asphalt and can melt and flow at a temperature below the heating mixing temperature of the asphalt mixture into a mixture containing a certain amount of crushed stone and crushed stone. A bituminous mixture used in rolled asphalt pavement.