JPS6076560A - Asphalt mixture - Google Patents

Abstract

PURPOSE:The titled mixture obtained by adding firbous magnesium oxysulfate (MOS) to asphalt concrete, and capable of sufficiently preventing the flow of paving surfaces with a small amount of an additive even if the compacting temperature is low. CONSTITUTION:An asphalt mixture obtained by adding >=0.1wt%, preferably 0.5-10wt% magnesium oxysulfate (MOS) expressed by formula I or II to asphalt concrete. The addition of MOS permits the absorbing and fixing of light oil causing the flow in the asphalt, increases the viscosity of asphalt cement and prevents the flow of paving surfaces. MOS is a very bulky fibrous material of needle-like crystal structure having 2.0-2.5 true specific gravity, 1-200mum length, 0.1-2mum diameter and 0.05-0.2 bulk specific gravity, and the oil absorption is 200-500ml based on 100g MOS.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to flow resistant asphalt pavement mixtures. Increase in car traffic on asphalt roads (1) h
1 Road surface ruts occur frequently and have become a major problem. The main reason for this is, of course, that the wheel load is large and the vehicle travels on the same track.
? The softening of the asphalt pavement due to the ν and the rutting phenomenon is the tentative title.

As a countermeasure to this problem, as described in the "Asphalt Pavement Guidelines" revised in June 1971, asphalt can be modified by adding rubber or resin, or hard asphalt with low penetration can be used to improve the A1i temperature of the asphalt mixture. It has been proposed to prevent rutting by increasing the viscosity of the aggregate and increasing the adhesion between the aggregate particles. However, this modified asphalt is not easily available everywhere and is expensive. Furthermore, conventional asphalt mixtures containing glass and rubber additives have had the problem of high tamping temperatures during paving and poor workability.

An object of the present invention is to provide an asphalt mixture that can sufficiently prevent the flow of an asphalt pavement surface with a small amount of additives even when the tamping temperature during paving is low.

A' for asphalt concrete according to the invention
i, MrSO, ・5Mc-0-RH-01+ M
A flow-resistant asphalt mixture is provided which includes the addition of a compound represented by MrSO, .5Mr(OH)-.3H20.

According to the present invention, the addition of fibrous magnesium oxysulfate (basic magnesium sulfate, hereinafter referred to as MO8) absorbs and fixes light oil in asphalt that causes fluidity, reducing the viscosity of asphalt cement. can be prevented from flowing on the asphalt pavement surface.

The MOS used in the present invention is MgSO4・5Mg0・8H2
It is a synthetic inorganic compound represented by 0 or MgSO4.5Mg(OH)2.3H20. This MOS is, for example,
It can be produced by dispersing magnesium oxide or magnesium hydroxide in an aqueous magnesium sulfate solution and subjecting it to a heating reaction, or by dispersing magnesium hydroxide in a sulfurized solution and subjecting it to a heating reaction (Patent Application No. 1983). -52364).

The general form of MOS is true specific gravity: 2. θ~2.5, length;
It is a fibrous material with an extremely bulky needle-like crystal structure having a diameter of 1 to 200 μm, a diameter of 0.1 to 2 ttm, S bulk specific gravity of 0.05 to 0.2. Also, the oil absorption amount of MOS is MO81
00/This D 200~5-00m1C.

The amount of S to be added is at least 0.1% by weight, preferably 0.3% by weight, based on asphalt concrete with a normal mix.
More preferably, the content is in the range of 0.5 to 1.0% by weight. Addition amounts exceeding 10% by weight are not preferred because they significantly impair the adhesive strength of asphalt concrete.

Furthermore, MOS may be added to the asphalt mixture in powder form, or it may be granulated to an appropriate size, e.g.
Preferably 2III11 or less, bulk specific gravity 0.1
It may be prepared in the form of granules of ~0.5.

MOS i Normally mixed asphalt concrete IJ-1
- When adding aggregate, filler, and asphalt, whether in the form of powder or granules, add aggregate, filler, and asphalt using conventional procedures.
Furthermore, MOS may be added, or even if MOS is added to the aggregate or filler in advance and asphalt is added, the physical properties of the resulting asphalt mixture will not be affected. Furthermore, there is no effect on the tamping temperature or workability. Furthermore, it can be used for road repair (heat reforming), which is a recent construction method, and can exhibit flow resistance even when compaction (tamping) temperatures are low (130 to I 10'C). .

Furthermore, MOS can be used in combination with other additives such as combs, resins, inorganic anti-flow agents, and even softeners.

Next, the present invention will be specifically explained using examples.

[Reference Example] Production Example of MOS Magnesium sulfate, heptahydrate 9 y is dissolved in 120 t of water, and 2.25 kg of magnesium hydroxide and about 400 y of MO8 serving as seed crystals are dispersed in this solution.

This dispersion was placed in an autoclave with an internal volume of 170 tons,
1701: for 3 hours. The formed precipitate was taken out and washed with water to remove excess magnesium sulfate.
Dry and crush at 0°C, bulk specific gravity 0.08, average length 401
A MOS with a 1 m % average diameter of 0.7 was obtained.

The obtained MOS was confirmed by powder X-ray diffraction and an infrared spectrophotometer, and was used as a sample for the following experiment.

Example 1 The aggregate particle size was adjusted to the median value of the standard particle size formulation of asphalt pavement outline dense particle size Ascon, and asphalt with a penetration degree of 60 to 80 was prepared. The asphalt mixture was prepared with an og temperature of 1, and a MOS of 0.3 and 0.5, respectively.

A test piece was prepared in accordance with the Asphalt Paving Guidelines by adding 0.7% by weight, and a Marshall stability test was conducted in accordance with the Asphalt Paving Guidelines.

The test piece preparation conditions are shown in Table 1, and the results are shown in Table 2.

Table 1 Comparative Example 1 of Test Piece Preparation Conditions A test piece was prepared under the same conditions as in Example 1 without adding any additives, and a Marshall stability test was conducted. The results are shown in Table-2.

Example 2 The same aggregate and asphalt as in Example 1 were used, the amount of asphalt added was 5.8% by weight, MOS was added in a predetermined amount, and test pieces were made under the conditions shown in Table 3 according to the asphalt pavement guidelines. The model was created and subjected to Marshall stability tests. The results are shown in Table-2.

Table 3 Comparative Example 2 of Test Piece Preparation Conditions A test piece was prepared under the same conditions as in Example 2 without adding any additives, and a Marshall stability test was conducted.

The results are shown in Table-2.

Comparative Example 3 Under the same conditions as in Example 2, a commercially available oil-absorbing additive (0R-60 manufactured by Osaka Cement Co., Ltd.) coated with gypsum and cement was applied to the surface of a blast furnace sill at 4 and 6.8 g, respectively.
A test piece to which heavy liquid H was added was prepared and subjected to a Marshall stability test. The results are shown in Table 2.

Example 3 MOS was set to 0 under the same conditions as in Example 2.
．． Wheel tracking test pieces containing 0.3%, 0.5%, and 0.7% by weight were prepared and tested in accordance with the asphalt pavement guidelines. The results are shown in Table-4.

Comparative Example 4 A test piece for wheel tracking was prepared under the same conditions as in Example 2 without adding any additives, and tested in accordance with the asphalt pavement guidelines. The results are shown in Table-4.

Comparative Example 5 Under the same conditions as in Example 2, gypsum and cement-coated commercially available oil-absorbing additives (0R-60 manufactured by Osaka Cement Co., Ltd.) were added at 4 and 6.8 wt. A test piece was created and tested in accordance with the asphalt pavement guidelines. The results are shown in Table-4.

Example 4 MOS was granulated, and 31! A test piece was prepared by adding 0.5 weight of the granulated product under the conditions shown in Table 1. Marshall stability tests were conducted on these in accordance with the asphalt pavement guidelines.

The results are shown in Table-2.

Table-4 Wheel tracking test Test temperature: 60℃ Load: 6.4 kg/d Improvement in shimmar stability was observed with the addition of MOS.
It is clear that high flow resistance can be obtained with an extremely small amount compared to commercially available inorganic oil absorbents, and that sufficient performance can be exhibited even at low rolling (compaction) temperatures.

Claims (3)

[Claims] (1) A flow-resistant asphalt mixture obtained by adding a compound represented by the following formula % to asphalt concrete. (2) The mixture according to item 1, wherein the amount of the compound added is 0.1 to 10% by weight. (3) The shape of the compound is 1 to 200 μm in length and 0.5 μm in diameter.
2. The mixture according to item 1, which is acicular or fibrous with a diameter of 1 to 2 μm.