JPH06305793A - Softening and deformation-preventing material for asphalt mixture - Google Patents

Abstract

PURPOSE:To obtain a softening and deformation-preventive material for asphalt mixture provided with adequate oil absorptivity and uniform dispersibility by blending a formed material obtained by alkali-treating a fly ash, the fly ash, steel making dust and a blast furnace cement to form a granulated material. CONSTITUTION:This softening and deformation-preventive material for asphalt mixture is composed of the granulated material prepared by kneading 10-20 pts.wt. porous formed material obtained by alkali-treating the fly ash, 20-40 pts.wt. fly ash, 10-20 pts.wt. steel making dust containing >90% iron and30-50 pts.wt. blast furnace cement, then by granulating, aging and drying. It is preferable that 60-70wt.% molded material is 3-0.6mm in particle diameter and balance is <=0.6mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asphalt pavement material, and more particularly to an anti-flow deformation preventing material for an asphalt mixture.

[0002]

[Prior Art] Asphalt pavement road surface anti-flow measures such as so-called modified asphalt with organic modifiers such as semi-blown asphalt, asphalt with rubber, and asphalt with thermoplastic resin are used. There is.

However, these modified asphalts are
There are drawbacks in the construction work such as that the construction temperature of the mixture must be maintained at a high temperature, the mixture easily adheres to the rollers during compaction, and joint breakage occurs. Further, there is a problem that the material cost and the construction cost are increased.

As another anti-flow measure, asbestos, methyl cellulose, slaked lime, cement, etc. are added,
How to absorb light oil during asphalt paving work,
Attempts have been made to add a special oil absorbing material for preventing the flow of asphalt, which is granular.

For example, the particle size of 10 disclosed in JP-A-57-187402 and JP-B-57-22350 is disclosed.
mm or less of natural aggregate or artificial aggregate as a seed stone, to which powder rubber or thermoplastic resin alone or a mixture of both,
Alternatively, it is a material coated with three kinds of hydraulic materials such as cement, blast furnace slag and gypsum.

However, these oil-absorbing aggregates for asphalt flow prevention use relatively large amounts of cement and granulation, which are hydraulic materials, as raw materials, so that the inner diameter of pores exhibiting oil absorption is large, The adsorption rate is slow due to the capillary phenomenon.

Therefore, when used as an asphalt pavement material for cold regions, which contains a larger amount of filler than the ordinary asphalt pavement material, after the paving work, the temperature of the pavement layer should be lowered to a predetermined traffic release temperature. Even if you wait, there is no time to absorb the light oil in the asphalt,
The initial rut occurs and the so-called flow prevention effect is not exhibited early.

As another anti-flow measure, Japanese Patent Application No. 1-
No. 46820 discloses the use of coal ash sand in which fly ash is granulated with cement or the like, and it is said that the asphalt pavement material having a significantly improved resistance to initial ruts and high fluidity resistance can be obtained.

The coal ash sand used is 10 to 20 μm.
Since very fine fly ash is used as the main raw material for granulation, many very fine holes are distributed on the surface.

When this coal ash sand is added to the asphalt mixture, the light oil component contained in the asphalt mixture is efficiently adsorbed or absorbed in a short time.

However, since the specific gravity of the above coal ash sand is very small as compared with the specific gravity of other aggregates forming the asphalt mixture, the dispersion of the asphalt mixture at the time of kneading is not sufficient, and at the time of construction, it is not applied to the road surface. It becomes easy to be unevenly distributed.

[0012] As a result, the oil absorption progresses partially due to the uneven distribution of coal ash sand, and the workable time is shortened due to the oil absorption speed being too high. There was a problem of cracking. Further, there is a drawback that the amount of wear of the unevenly distributed portion of coal ash sand is large.

Further, as another anti-flow measure, Japanese Patent Laid-Open No.
No. 001242 discloses an oil-absorbing aggregate obtained by granulating zeolite powder obtained by treating fly ash with alkali as a main raw material.

In this granulated oil-absorbing aggregate, the raw material itself has fine pores having an oil-absorbing property, and secondary pores due to granulation are present in the same manner as in the case where the fly ash is granulated. The oil absorption rate is very high because the holes are concentrated in the fine parts.

However, since the specific gravity of the granules of zeolite made from fly ash is small, the dispersion of the asphalt mixture at the time of kneading is not sufficient like the above-mentioned coal ash sand, and it is unevenly distributed on the road surface during construction. It will be easier.

As a result, if the oil absorption progresses partially due to the uneven distribution of zeolite, or the oil absorption speed is too high, the workable time becomes short, and the time until the compaction after kneading is long,
There were problems such as poor compaction and cracks.

Further, there is a drawback that the amount of wear of the zeolite unevenly distributed portion is large. It is possible to reduce the amount of oil-absorptive aggregate added in order to alleviate the problem of poor compaction, but since it is premised that pavement work is performed throughout the winter and summer, the amount added should be based on winter. Then, there is a problem that the flow resistance effect becomes insufficient during the high temperature period of summer and ruts occur.

[0018]

As described above, the kneading material for imparting flow resistance to conventional asphalt is expensive, has excessive oil absorption, has a short construction time, and has a short asphalt mixture. There are merits and demerits, such as the problem of uniform dispersibility with, and there is a demand for an asphalt mixture that solves these problems, especially from the viewpoint of securing a safe pavement surface against the increasing trend of heavy vehicle traffic. Is extremely high.

In order to meet such a demand, the present invention is an additive composition of an asphalt mixture exhibiting excellent economical efficiency and workability and fluidity resistance, that is, an asphalt mixture having appropriate oil absorption and uniform dispersibility. It is an object of the present invention to provide a softening and deformation preventing material.

[0020]

According to the present invention, 10 to 20 parts by weight of a porous product obtained by subjecting fly ash to alkali treatment, 20 to 40 parts by weight of fly ash, and 10 to steelmaking dust containing iron of 90% or more. A softening and deformation preventing material for an asphalt mixture, which comprises a granulated product obtained by kneading, granulating, curing and drying 20 parts by weight and 30 to 50 parts by weight of blast furnace cement.

In the present invention, the granules have a particle size of 3 to
0.6 mm: 60 to 70% by weight, the balance being less than 0.6 mm, the softening and deformation preventing material for an asphalt mixture according to claim 1.

[0022]

[Function] Since a porous product obtained by treating fly ash with alkali, so-called zeolite, has many fine pores of 10 nm or less, it has the property of rapidly absorbing light oil contained in the asphalt mixture. There is.

The particle diameters of the above porous product, fly ash and blast furnace cement are approximately the same as 10 to 30 μm, and when a mixture of this mixture and steelmaking dust having a particle diameter of 10 to 40 μm is granulated. Since the particle size composition of the mixture has a narrow distribution of 10 to 40 μm, pores are formed between the particles in the obtained granulated product.

Moreover, during the hydraulic setting process of the mixture, the blast-furnace cement is bonded together with the hydraulic material such as fly ash while forming a relatively large acicular ettringite.
The size of the pores is 10 to 50 nm, and although the oil absorption rate is not fast, it has an oil absorption property of continuing oil absorption.

The present invention provides a granulated product in which the amounts of the porous product, fly ash and blast furnace cement are adjusted, whereby the granulated product has fine pores of 10 nm or less and 1
The amount of pores of 0 to 50 nm is adjusted, and it is possible to secure pores having two different oil absorbing properties, that is, absorbing light oil contained in the asphalt mixture rapidly and in an appropriate amount and gradually absorbing oil. The possible time can be appropriately extended and adjusted, and the flow resistance corresponding to the initial rut is expressed, and further, the flow resistance effect in the high temperature period of summer can be achieved.

Further, according to the present invention, the above oil-absorbing granules are blended with a proper amount of specific steelmaking dust, so that the granulation can be carried out without disturbing the above-mentioned formation of 10 to 50 nm pores having the property of gradually absorbing oil. The specific gravity of the granules is, for example, 2.5 to 2.6.
Since it can be adjusted in the range of, and can be approximated to the specific gravity of other aggregates constituting the asphalt mixture,
When the asphalt mixture is kneaded and the pavement construction work is performed, uneven distribution of granules due to the difference in specific gravity is eliminated, and the granules can be dispersed almost evenly in the pavement layer, so that stable flow resistance can be imparted.

In the present invention, the particle size of the granulated product is 3 to 0.
6 mm: 60 to 70% by weight, the balance is less than 0.6 mm, and it was specified in correspondence with the particle size of other aggregates constituting the asphalt mixture, so other coarse aggregates, medium aggregates, fine grains It can be evenly distributed in the gaps of the aggregate.

Therefore, the oil absorption of the oil-absorbent granules is evenly expressed in the pavement layer in synergy with the effect of adjusting the specific gravity of the granules, so that the flow-preventing effect is enhanced on average.

In the present invention, the porous product obtained by subjecting the fly ash having a particle size of 10 to 30 μm to alkali treatment is a particle having a large number of fine pores of 10 nm or less and having a high water absorption property. Is.

If the blending amount is less than 10 parts by weight, the amount of light oil contained in the asphalt mixture to absorb oil rapidly becomes insufficient, and the effect of preventing the occurrence of initial ruts decreases.

On the other hand, if it exceeds 20 parts by weight, the rapid oil absorption becomes excessive, the workable time is shortened, and the workability is lowered.

Further, the fly ash and the blast furnace cement combine to form needle-like ettringite by a hydraulic reaction between them to form predetermined pores, and when the content of the fly ash is less than 20 parts by weight. , Gradually absorb the light oil contained in the asphalt mixture 10
The 50 nm pores are reduced and the oil absorption is reduced. On the other hand, if it exceeds 40 parts by weight, excessive pores will be formed.

The blast-furnace cement functions as a binder for the granulated material. By limiting the blast-furnace cement to cement among the cements, it is possible to form a needle-like ettringite that is larger than cement such as Portland cement. It is a thing.

If the blending amount of this blast furnace cement is less than 30% by weight, the strength of the granulated product is lowered.

If it exceeds 50% by weight, it is 10 to 50n.
The number of pores of m becomes small and the oil absorption becomes insufficient.

Steelmaking dust containing 90% or more of iron is dust separated and recovered from exhaust gas generated when steel is blown in a converter, which is a steelmaking furnace, for example.

The steelmaking dust has a particle size of 10 to 40 μm.
So-called converter secondary ash, which is composed of m iron particles and 90% iron oxide, is optimum.

If the blending amount of the steelmaking dust is less than 10%, the amount of adjusting the specific gravity of the mixture is insufficient. Further, if it exceeds 20% by weight, the strength of the granulated product decreases.

Further, in the present invention, the particle size of the granulated product is
3 to 0.6 mm: 60 to 70% by weight, the balance 0.6 mm
As the particles are composed of less than, it is an asphalt constituent, such as rubble stone, for example, 5 to 13 mm and 2.5 to 5
mm coarse aggregate, 2.5 mm or less river sand, 0.6 mm or less sea sand, 0.15 mm filler such as limestone, etc. blended in a predetermined ratio between particles or in pores formed between the particles It can be dispersed.

3 to 0.6 mm: If less than 60% by weight or more than 70% by weight, the dispersion in the pores formed between coarse-grained and medium-grained aggregate particles becomes insufficient.

If less than 0.6 mm is less than 30% by weight, the dispersion in the pores formed between the trickle-grain aggregate particles becomes insufficient.

[0042]

[Example] 30 parts by weight of fly ash, blast furnace cement 4
0 parts by weight, 10 parts by weight of a porous product obtained by subjecting fly ash to alkali treatment, and 10 parts by weight of secondary converter secondary ash were kneaded and granulated with an Erich mixer while adding water.

After curing for 7 days, 3 to 0.6 mm: 65
%, Less than 0.6 mm: 35% was used as the material of the present invention.

Conventional material 1 is coal ash sand having a particle diameter of 2.5 to 0.15 mm, which is similar to that of JP-A-01-046820, and conventional material 2
The oil-absorbing aggregate made of natural aggregate having a size of 5 mm or less, cement, blast furnace slag and gypsum similar to JP-A-57-187402 was used.

The properties are shown in Table 1. The materials of the present invention are characterized by high crush strength, relatively high oil absorption, and high specific gravity. The specific gravity was adjusted to the same value as the aggregate that constitutes the asphalt mixture.

[0046]

[Table 1]

Note) Measurement of oil absorption and water absorption: The dried aggregate is immersed in water or kerosene for 3 hours, and then the attached water or oil is removed by a centrifuge.

The weight increase of the sample after water absorption or oil absorption is measured, and the weight ratio with the sample before the test is determined.

Next, four kinds of asphalt mixture A containing the material of the present invention, asphalt mixture B containing the conventional material 1, asphalt mixture C containing the conventional material 2 and asphalt mixture D containing no flow resistance additive are used. Wheel-tracking tests were performed on the asphalt mixture.

The amount of asphalt added is 5.5%, and the amount of each oil-absorbing aggregate added is 40% when added in volume ratio to the amount of asphalt because the specific gravity of each oil-absorbing aggregate is different.
And Table 2 is a comparison table of DS values based on the test results.

[0051]

[Table 2]

Note) DS value (dynamic stability): 1 mm number of passages of traveling wheels required for sinking (times / mm)

As shown in Table 2, the DS values of the asphalt mixtures A, B and C containing the oil-absorbing aggregates are higher than those of the asphalt mixture D containing no oil-absorbing aggregates.

In particular, after curing at 60 ° C. for 7 days, the DS values of the materials A and B reached the level of 6000 times / mm, respectively, and exhibited the effect as a rut-proofing material.

However, the material B has a DS value of 55 immediately after paving.
As is clear from the very large value of 00 times / mm, it was difficult to carry out pavement construction, particularly rolling work, from excessive oil absorption due to the rapid oil absorption characteristics.

The material C has a DS value immediately after paving and is a material A.
It was smaller than that of No. 1, and there was an initial rut just after paving.

The material A has a DS value of 4000 times / mm immediately after paving without fear of initial rubbing, and the DS value is steadily improving with subsequent curing.

Next, three kinds of asphalt mixture A containing the material of the present invention, asphalt mixture B containing the conventional material 1, asphalt mixture C containing the conventional material 2 and asphalt mixture D containing no flow resistant additive. Table 3 shows the results of the abrasion resistance test conducted on the asphalt mixture.

The samples were cut out of use after the wheel tracking test after 7 days of curing.

[0060]

[Table 3]

Note) Abrasion test: A sample is set on the inner surface of a ball mill, and it is rotated together with water and steel balls for 24 hours to measure the amount of abrasion loss.

In the materials B and C, uneven distribution of the oil-absorbing aggregate is unavoidable, and the wear loss is large. Compared with the base asphalt mixture D, the material A of the present invention has a smaller amount of wear.

Since the material of the present invention has a large specific gravity and has an optimum particle size distribution, it is uniformly dispersed in the asphalt mixture.
It is thought that this was due to the fact that even the gaps between the small aggregates entered the oil and absorbed the oil to exert its effect.

[0064]

EFFECTS OF THE INVENTION The asphalt mixture containing the flow-deformation-preventing material (oil-absorbing aggregate) according to the present invention exhibits an effect as an asphalt pavement with little initial rubbing immediately after paving and high dynamic stability. You can

Further, the anti-fluid deformation preventing material for an asphalt mixture according to the present invention is used for processing fly ash generated during coal combustion in a thermal power plant, a porous product obtained by subjecting the fly ash to alkali treatment, and blast furnace slag generated during iron making. Industrial wastes such as blast furnace slag and steelmaking dust are recycled as raw materials and can be manufactured at low cost.

Claims (2)

[Claims] 1. 10 to 20 parts by weight of a porous product obtained by treating fly ash with an alkali, and fly ash 20 to 20 parts by weight.
Steelmaking dust containing 40 parts by weight and iron content of 90% or more 10
Knead 20 parts by weight and 30 to 50 parts by weight of blast furnace cement,
A softening and deformation preventing material for an asphalt mixture, characterized by comprising granulated, cured and dried granules. 2. The particle size of the granulated product is 3 to 0.6 mm:
The softening and deformation preventing material for an asphalt mixture according to claim 1, wherein the content is 60 to 70% by weight and the balance is less than 0.6 mm.