JP2000290053A - Mixture for pavement excellent in skid resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a paved body having excellent skid resistance by controlling the difference of Los Angeles percentage of abrasion between regenerated aggregate and fresh aggregate to equal to or above a specific value. SOLUTION: The fresh aggregate having hardness different from that of the coarse aggregate part in a regenerated mixture for pavement is used. When the hardness is expressed by Los Angeles percentage of abrasion, the fresh coarse aggregate having the hardness different by >=3% compared to the regenerated coarse aggregate is used. The ratio of the fresh coarse aggregate and the regenerated coarse aggregate by weight is preferably 1:2 to 2:1. The harder fresh aggregate is preferably used from the view point of durability, through the fresh coarse aggregate can be used whether harder than that of the regenerated coarse aggregate or softer. As the hard aggregate, steel making slag or alloy iron slag is preferably used. The regenerated mixture using the slag can be used for a road, where the traffic is busy. The mixture can usually be manufactured in a regenerated mixture production plant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reclaimed pavement mixture, and more particularly to a reclaimed pavement mixture having excellent slip resistance.

[0002]

2. Description of the Related Art The slip resistance of a road surface when wet is mainly dependent on the frictional resistance between an aggregate and a tire used in a pavement mixture. Therefore, using a material that is square and wear-resistant, reducing the amount of fine particles including the binder and allowing more aggregate to appear on the surface, a macro-rough road surface is formed, and slip resistance is reduced. A pavement having excellent properties can be obtained. Such a paving mixture includes an open particle type mixture and a gap type mixture.

[0003] In order to increase the number of protrusions on the road surface, the open-grain-based mixture is formed by coarsening the aggregate particle size so that the aggregate particles are exposed to the surface as much as possible. However, the open-grain type mixture is inferior in durability and water resistance as compared with the dense-grain type mixture, and is very rarely applied to the surface layer of the road from the viewpoint of road maintenance.

[0004] On the other hand, the gap-based mixture is used to improve the disadvantages of the open-grained mixture and to maintain the surface roughness. Is removed. However, although the gap type mixture is superior in durability to the open particle size type mixture, it is inferior to the exclusion of water between the road surface and the tire, which causes slip when wet, and a dry surface of the road surface in contact with the tire is obtained. Hateful.

[0005] In recent years, asphalt binders have been improved, and it has become possible to apply an open particle size mixture to a road as a drainable pavement. However, drainable pavement mixtures
There is a problem in that the asphalt mortar on the surface of the pavement body is dragged by the running of the tire and the function of causing a phenomenon such as crushing of a gap or a clogging of a gap caused by dust particles closing the gap has been a problem. Therefore, the drainage pavement mixture uses a high-quality asphalt binder, and it is necessary to take measures to maintain the function, so that the total cost is much higher than the general mixture. I also have problems.

In addition, as a method of forming a rough road surface macroscopically, a pavement using two kinds of coarse aggregates having different wear characteristics is constructed, and the aggregate having a soft surface is worn by a tire of a passing vehicle. A method (JP-A-47-42271) is known. However, this method requires a complicated test of BS in the selection of coarse aggregate, uses a unique combination theory to design the blending particle size, and uses two types of aggregates having different wear characteristics. Therefore, it is hardly used because of the necessity of an extra stock yard in the mixture factory.

[0007] On the other hand, a great deal of research and development has been conducted on recycling-related technologies in the field of pavement, including construction by-products as well as by-products from other industries.
It has already been standardized according to outlines. A representative example is the “Plant for Recycling Pavement Technology” (December 1992
There is a recycled asphalt mixture shown in the Japan Road Association. Due to crushing and classification of asphalt concrete lumps and the like, the production amount of a recycled asphalt mixture reused as recycled asphalt aggregate has been increasing year by year, and in recent years, the proportion of the production amount of the asphalt mixture, which has remained almost unchanged, has also increased. However, the recycled aggregate is used only as a normal dense-grained mixture, a coarse-grained mixture, or a flow-resistant improvement mixture obtained by adding an asphalt modifier or the like thereto. Since the recycled aggregate is composed of coarse aggregate and asphalt mortar, it cannot be an open-grained mixture, and no effective mixture having excellent slip resistance has been obtained.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reclaimed pavement mixture having excellent slip resistance.

[0009]

SUMMARY OF THE INVENTION A first aspect of the present invention is a regenerated mixture for pavement comprising a coarse aggregate portion composed of recycled coarse aggregate and a new coarse aggregate. A recycled pavement mixture characterized by a Loss Loss Loss from Coarse Aggregate of 3% or more, preferably 5% or more. A second aspect of the present invention is the above-mentioned recycled mixture for paving, wherein the novel coarse aggregate is selected from steel slag and ferroalloy slag.

The pavement mixture is produced from aggregates called coarse aggregates, fine aggregates and fillers, asphalt, binders typified by cement and resin, and other additives as required. Coarse aggregate is aggregate having a larger particle size (greater than 2.36 mm) than sand, and crushed stone, crushed stone,
Gravel, steel slag, recycled aggregate, artificial aggregate, etc. Usually, the pavement mixture contains 20 to 85% by weight of coarse aggregate with respect to all aggregate.

The recycled asphalt mixture is obtained by adding a new aggregate, a new asphalt, and a regenerating additive as a supplement to the recycled aggregate and heating and mixing the mixture. As the recycled aggregate, the asphalt recycled aggregate is mainly used. Used for Recycled asphalt aggregate is obtained by crushing and classifying asphalt lump, and is often divided into 20 to 13 mm, 13 to 5 mm, 5 to 0 mm, or 20 to 13 mm, 13 to 0 mm. In the asphalt regenerated mixture, the regenerated aggregate is generally used in an aggregate weight ratio of 10 to 40%.

According to the present invention, a new coarse aggregate having a hardness different from that of the recycled aggregate is used for the coarse aggregate portion of the recycled mixture. Aggregate hardness, Mohs hardness, aggregate impact value,
In the present invention, the new coarse aggregate used in the present invention differs from the regenerated coarse aggregate by 3% or more, preferably 5% or more, in Los Angeles abrasion loss. In addition, the new coarse aggregate has a weight ratio of the recycled coarse aggregate of 1: 2.
２2: 1 is preferred.

The new coarse aggregate may be harder or softer than the recycled coarse aggregate.
It is preferable to use hard coarse aggregate from the viewpoint of durability. As the hard aggregate, silica sand, emery, silica, hard slag, fused alumina, etc. are used,
More preferably, steel slag or alloy slag is used. About 66% of crushed pavement stone produced in Japan is
Investigations have reported that Los Angeles abrasion loss is 20% (average 18%), and of course the quality of most recycled aggregates is presumed to be the same, and crushed stone that is usually used in a certain area is obtained in that area. New aggregates are often of the same quality as recycled aggregates, and it is difficult to find harder natural aggregates.
However, among steel slags, steelmaking slag has a quality of loss of less than 15% in Los Angeles abrasion, and is much easier to procure than natural hard aggregates.

The steel slag is obtained by crushing a product mainly composed of a nonmetal oxide produced in the iron making process, and comprises a blast furnace slag purified from a blast furnace in a pig iron manufacturing process, and a steel manufacturing process. And steelmaking slag produced in Blast furnace slag is divided into blast furnace decooled slag and blast furnace granulated slag according to the difference in cooling method, and steelmaking slag is divided into converter slag and electric furnace slag according to the method of producing steel. Iron and steel slag must be piled up outdoors to retain the appropriate moisture, so that free lime reacts with water to make the slag stable (aging).
The steel slag used for the pavement mixture is used after aging for three months or more. Loss of abrasion loss of steel slag which is generally commercially available is 15% or less as described above for steelmaking slag and 25% or more for blast furnace slag. Ferrochrome slag is harder than steelmaking slag. These slags, which are originally in a molten state, are artificial magmas, so that natural rocks differ in quality and hardness depending on the composition of the magma and the cooling conditions, for example, granite and basalt or eruptive and plutonic rocks. By controlling manufacturing conditions such as speed, a desired hard product can be obtained.

[0015] Steel slag and the like can be easily obtained when there is an ironworks or a harbor nearby, but otherwise transportation costs are high. However, in the present invention, one-third to two-thirds of the coarse bone portion of the regenerated mixture is made of, for example, steel slag, so that the dense-grained asphalt mixture (generally, the weight ratio of coarse aggregate to total aggregate is 40 to 60) is used. %) And the weight ratio of coarse aggregate to total aggregate is 50% by weight, the required amount of steel slag is only about 17 to 35% by weight, and the asphalt binder requires the production cost of expensive drainage mixture. It is not particularly expensive by comparison.

The regenerated mixture of the present invention using steel slag and / or ferroalloy slag can be used mainly on roads with heavy traffic. This regenerated mixture can be said to be harder on average than the ordinary regenerated mixture, but the road surface is in a state where the hard coarse aggregate and the ordinary aggregate are mixed,
Since hard aggregates are less worn than normal tires wear due to running of tires, a rough road surface is formed macroscopically, and a pavement with excellent slip resistance can be obtained. is there. If the present invention is not applied to heavy traffic roads, and if it is desired to form a macro-rough road surface at an early stage or to form a similar road surface over the entire width, sand blast, shot blast, Is preferably performed.

The production of the mixture of the present invention can be carried out in a usual regenerated mixture production plant. There are two methods for heating the recycled coarse aggregate: a method of heating with a drum dryer, a method of directly feeding into a mixer and heating by heating of new heated aggregate, and a method of synthesizing with new aggregate under the hot elevator. However, care must be taken to keep the ratio of new coarse aggregate and recycled coarse aggregate constant.

[0018]

EXAMPLES As a regenerated asphalt mixture, a dense particle gap asphalt mixture having a synthetic particle size as shown in Table 1 was prepared. Only 13 to 5 mm of the recycled coarse aggregate was used, and the blending ratio was 30%. 33% of new coarse aggregate ratio
Regarding (3), specimens were prepared from three types of (A) crushed stone, (B) iron and steel slag, and (C) silica stone. Table 2 shows the Loss Loss Loss of recycled coarse aggregate and each new coarse aggregate. The fine aggregate used was ordinary natural sand, the filler used was stone powder, and the binder used was 5% of petroleum asphalt 60 to 80 for paving. The specimen is 400 × 4
It was molded to a size of 00 × 50 mm, and a wear test was performed. The abrasion test was performed on the entire surface of the specimen with a diameter of 100 mm and a weight of 350 g.
Is run while rotating the donut-shaped wire brush with only the ground pressure of its own weight. During the test, the specimen surface is kept moist. In this test, the operation of the wire brush 2,000 times corresponds to the operation of D traffic for 10 days, and the operation of 3000 times corresponds to the operation after 100 days of traffic operation.

Slip resistance (BPN) before and after the test
Is as shown in Table-3. From the above results,
It was found that the slip resistance was better in the order of (C) and (B) than in (A). That is, when the coarse aggregate of the asphalt regenerated mixture is composed of the regenerated aggregate and the new aggregate, if the Loss on the grinding loss of the regenerated aggregate and the new aggregate is adjusted to be 3% or more different, the asphalt regenerated mixture is used. It was confirmed that the slip resistance of the pavement to be constructed after service was improved, and that the greater the difference in weight loss in Los Angeles slip, the greater the effect of improvement in slip resistance.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

According to the present invention, a regenerated mixture for pavement having a Loss Loss Loss of 3% or more between the recycled coarse aggregate and the new coarse aggregate can produce a regenerated mixture excellent in slip resistance and easily excellent in slip resistance. It became possible to obtain a paved body. In addition, the recycled mixture for pavement using steel slag as the new coarse aggregate has made it possible to cope with heavy traffic roads. The slip resistance of the mixture of the present invention is caused by a difference in abrasion of the aggregate due to a difference in hardness, and forms a rough road surface macroscopically, thereby obtaining a pavement having excellent slip resistance. it can. In addition, the road surface of the pavement using the mixture of the present invention eliminates water between the tire and the road surface, which causes slippage when wet, and provides a dry surface of the road surface in contact with the tire. Has the same effect as paving. Therefore, it is possible to use an expensive binder and apply it to a place where the application is hesitated because of an increase in maintenance costs, which can contribute to ensuring the safety of vehicle traffic.

Claims (2)

[Claims] 1. A recycled mixture for pavement comprising a coarse aggregate portion composed of recycled coarse aggregate and new coarse aggregate, wherein the loss of Los Angeles abrasion between the recycled coarse aggregate and the new coarse aggregate is 3%. A recycled mixture for paving, characterized in that it is different from the above. 2. The recycled mixture for pavement according to claim 1, wherein the new coarse aggregate is selected from steel slag and ferroalloy slag.