JP2909335B2 - Sintered artificial aggregate for road pavement and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered artificial aggregate for road pavement and a method for producing the same, and more particularly to a sintered artificial aggregate for road pavement having excellent mechanical strength and wear resistance, and its advantages. The present invention relates to a simple manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as aggregate for road pavement, crushed stone which is naturally collected and relatively inexpensive has been used. However, natural crushed stone has a limited amount of collection, and it is difficult to obtain a large amount of particles having a desired particle size distribution. Therefore, in a road pavement aggregate using such natural crushed stone, the quality is stable. It is difficult to get a lot of things. Moreover, these natural crushed stones are inferior in abrasion resistance and mechanical strength. Therefore, when used as aggregate for road pavement, the following problems are caused.

That is, the natural crushed stone on the surface layer of the road is worn out by friction with the tires of vehicles traveling on the road, and the flatness of the road surface is impaired.
On roads with a large traffic volume, such wear is more remarkable, so that a rut is formed on the road surface, and it is easy for a passing vehicle to take a steering wheel on the rut. It can cause Therefore,
In such a road, it is necessary to repair the vehicle at a relatively short cycle. In particular, on a highway where vehicles pass at high speed, such road repair is performed more frequently in order to secure the safety of passing vehicles. Must be performed, and consequently,
Significant costs and labor will be spent on road maintenance and management.

[0004] In snowfall areas, natural crushed stone, which is used for the surface layer of a pavement road, is scraped off by the use of tire chains, spike tires, and the like of passing vehicles in winter, and the crushed natural crushed stone is used. Dust has caused serious dust pollution.

[0005]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a road paving sinter having excellent mechanical strength and high abrasion resistance. An object of the present invention is to provide an artificial bone aggregate and a manufacturing method capable of advantageously obtaining the aggregate.

[0006]

In order to solve the above problems, the present invention is characterized in that Al ₂ O ₃ is 60% by weight or more, SiO ₂ is 0 to 40% by weight, and MgO is 0% by weight.
-5% by weight and a total composition of unavoidable impurities derived from the raw materials thereof and 100% by weight, and has a dense porosity of 8.0% or less. A sintered artificial aggregate for road pavement having a structure.

Further, the present invention is that the aluminum hydroxide or aluminum oxide Al ₂ O ₃ source material, SiO ₂
Using silica or kaolin as a source material and magnesium hydroxide or magnesium oxide as a MgO source material, Al ₂ O ₃ is 60% by weight or more, SiO ₂ is 0 to 40% by weight, and MgO , And the raw materials are blended such that the total amount of them and the inevitable impurities derived from the raw materials is 100% by weight. Crush and mix so that the diameter is 300 μm or less,
A method of manufacturing a sintered artificial aggregate for road pavement, which is formed into a molded article having a predetermined size and then fired at a temperature of 1700 ° C. or more, is also characterized.

[0008]

More specifically, the sintered artificial aggregate for road pavement according to the present invention is a ceramic material containing Al ₂ O ₃ as a main component and SiO ₂ and MgO as subcomponents. In such sintered artificial aggregate,
Al ₂ O _{3, which} is a main component, must be contained in an amount of 60% by weight or more. Alkali, Al ₂
This is because when the content of O ₃ is less than 60% by weight, it is not possible to effectively improve the wear resistance and the mechanical strength as compared with the conventional aggregate for road pavement. In addition, of course, such a sintered artificial aggregate may be composed of only Al ₂ O ₃ , and by doing so, both of these properties are lower than those of a conventional road pavement aggregate. Will be further improved.

Generally, SiO ₂ is made of Al ₂ O
It can be obtained cheaper than ₃ . Further, as is well known, in a sintered body obtained by adding and mixing such SiO ₂ to Al ₂ O ₃ and sintering them, the crystal phase is SiO ₂ and Mullite crystals generated by Al ₂ O ₃ and corundum crystals by surplus Al ₂ O ₃ coexist, thereby exhibiting excellent properties in mechanical strength and wear resistance. Becomes However, on the other hand, Si
In the sintered body containing more than 40% by weight of O ₂ , the mullite crystals decrease and the vitreousness increases. On the other hand, the mechanical strength and the wear resistance are reduced. It will be lost.

Therefore, in the sintered artificial aggregate for road pavement according to the present invention, the content of SiO ₂ is permitted as a filler, but the content is within the range of 0 to 40% by weight. Must have been. By doing so,
Product cost can be advantageously reduced without impairing the mechanical strength and wear resistance of the sintered artificial aggregate.

[0011] In such a sintered artificial aggregate, the total content of Al ₂ O ₃ and SiO ₂ is preferably 90% by weight or more, and 95% by weight or more. Is more preferable. In other words, impurities such as oxides other than Al ₂ O ₃ and SiO ₂
The content is desirably less than 10% by weight, and more desirably limited to less than 5% by weight. However, if impurities other than Al ₂ O ₃ and SiO ₂ are contained in a large amount in excess of 10% by weight, the production of vitreous will increase, and both of the above characteristics will be deteriorated. is there.

However, in the sintered artificial aggregate according to the present invention, the content of MgO is permitted within a range of 0 to 5% by weight, preferably 0 to 3% by weight. . Because MgO is contained in such a small amount in such a sintered artificial aggregate,
Advantageously, the coarsening of the corundum crystal is suppressed, and the grain structure is effectively densified, thereby greatly contributing to the improvement in mechanical strength and wear resistance of the sintered artificial aggregate. It is. It should be noted that, even if such MgO is contained in an amount exceeding 5% by weight with respect to the sintered artificial aggregate, problems such as an increase in vitreous generation are caused. Therefore, in such a sintered artificial aggregate, for example, the particle size of the raw material, the firing method, etc. are taken into consideration, and even if the content of such a small amount of MgO is not required, if the particle structure can be sufficiently densified, There is no need to intentionally include MgO.

That is, in this way, the sintered artificial aggregate according to the present invention has a dense particle structure, and the apparent porosity, which is an index, is 8.0. % Or less. This is because a material having a porous structure with an apparent porosity exceeding 8.0% cannot expect a drastic improvement in mechanical strength and abrasion resistance over the conventional aggregate.

[0014] In short, the sintered artificial aggregate for road pavement according to the present invention contains Al ₂ O in an amount falling within the above specified range.
₃ and MgO, the crystal phase of which is a corundum crystal alone or a corundum crystal and a mullite crystal coexisting, in terms of crystal structure, with excellent mechanical strength and wear resistance. Has become
Also, by containing a small amount of MgO, the particle structure is densified, and the apparent porosity is set to 8.0% or less, so that both of these characteristics are effective in the physical structure. It is configured so that it can be increased.

Therefore, in the sintered artificial aggregate for road pavement according to the present invention, both the mechanical strength and the wear resistance can be remarkably improved as compared with the conventional aggregate for road pavement. In addition, the use of such aggregates can advantageously extend the road repair cycle and reduce the cost and labor burden spent on road maintenance and management. Thus, the damage caused by dust generated when the road surface is scraped off can be reduced as much as possible.

Moreover, since such a sintered artificial aggregate for road pavement contains a large amount of Al ₂ O ₃ , it can advantageously contribute to whitening of the surface of the pavement road. Compared with conventional road pavement aggregates, fire resistance has also been improved, and fracture of aggregates due to frictional heat with tires of passing vehicles can be effectively prevented,
In addition, various excellent properties such as improvement in chemical resistance and erosion resistance can be exhibited.

Thus, such a highly useful and valuable sintered artificial aggregate for road pavement is manufactured as follows.

First, aluminum hydroxide or aluminum oxide is prepared as an Al ₂ O ₃ source material,
_{(2) A} predetermined amount of silica or kaolin is prepared as a source material, and a predetermined amount of magnesium hydroxide or magnesium oxide is prepared as an MgO source material.

The raw materials prepared there are those having the above-mentioned components, and are not particularly limited as long as they can give a specific chemical composition as described later after firing. Absent. That is, for example, Al ₂
Examples of the O ₃ source material include commercially available alumina clinker, aluminum hydroxide produced by the Bayer method, aluminum oxide obtained by heat-treating the same, natural bauxite, and a calcined product thereof.
As the iO ₂ source material, general silicon and silica sand having a silica component, kaolin having a silica component and a silica-alumina component, ban shale, and the like can be used. Still further, as the MgO source material, commercially available magnesia clinker, commercially available magnesium hydroxide and natural magnesite, and magnesium oxide obtained by heat-treating each of them can be used. In using these raw materials, it is not always necessary to select and use one kind from the above-described ones. Even if two or more kinds of each raw material are used in combination, there is no problem.

Next, after firing, Al ₂ O ₃
0 wt% or more, the SiO ₂ 0 to 40 wt%, and MgO
, And the raw materials are blended in the same manner as before so that the total amount of the raw materials and the inevitable impurities derived from the raw materials is 100 wt%.

Thereafter, the thus obtained composition is subjected to a pulverizing treatment. In the pulverizing treatment, it is necessary to carry out the pulverization so that the average particle diameter of the compound is 300 μm or less. . However, if the pulverized product obtained by the pulverization treatment has an average particle size of more than 300 μm, the particle size is too large.
In the subsequent heat treatment, homogenization and densification of the structure cannot be sufficiently achieved by firing, and it becomes difficult to obtain a sintered body having a dense structure with an apparent porosity of 8.0% or less. Because. From such a point, it is desirable that the average particle diameter of the compound after the pulverization treatment is 50 μm or less. Further, in the pulverization treatment, any conventionally known apparatus can be used as long as the average particle diameter as described above can be obtained, and any method of a wet type or a dry type can be employed. obtain.

Subsequently, the pulverized materials are uniformly mixed by a general method according to the pulverization method to obtain a mixture. That is, for example, when all the pulverized products are obtained by a wet pulverization method and all of them are in a slurry state, they are directly stirred by a stirrer, If any of the pulverized materials is in the form of a slurry and the others are in the form of a cake, or if all of the pulverized products are in the form of a cake, they are kneaded with a kneading machine. A mixture is obtained, and any of the pulverized products is a slurry or cake obtained by a wet pulverization method, and the other is a dry powder obtained by a dry pulverization method. After adding pure water to the dried powder to make a cake, the pulverized materials are kneaded with a kneading machine, and further, all of the pulverized materials are dry powders obtained by a dry pulverization method. In some cases, the pulverized With or kneaded in a machine,
You get a mixture.

In addition, the pulverizing process and the mixing process for the raw material mixture can be performed simultaneously.
Of course, it can be carried out by any conventionally known device, but also in this case, for the same reason as described above, the average particle size of the obtained pulverized mixture is 300 μm.
These processes must be performed so as to be less than or equal to m. Also, even when such an apparatus is used, it goes without saying that either a wet method or a dry method can be adopted.

Next, a granulation operation is performed on the pulverized mixture thus obtained to obtain a granulated product. In addition, such a granulation operation is performed by a general method according to a pulverization and mixing technique of the pulverized mixture to be granulated. For example, the slurry obtained by the wet mixing method is granulated into pellets or the like by an extruder or the like, and the slurry obtained by the dry mixing method is dry granulated by a rolling granulator or the like. It does. In any case, by such a granulation operation, the crushed mixture is generally 5 to
It is granulated to have an average particle size of 50 mm.

Thereafter, the granules are dried as necessary, and then dried at a temperature of 1700 ° C. or more, preferably 1700 to 190 ° C.
Bake at a temperature of 0 ° C. Thus, the apparent porosity is 8.0
% Is obtained. When firing such granules, any general firing equipment such as a rotary kiln, a tunnel kiln, or a shaft kiln may be used, but at that time, if the firing temperature is lower than 1700 ° C, The internal structure of the obtained sintered body cannot be sufficiently densified, and the apparent porosity is 8.0%.
May be larger than

The sintered body thus obtained is used as it is or after being subjected to a general sizing operation, and is used as a target sintered artificial aggregate for road pavement. They are mixed and used as concrete. In addition, such a sintered artificial aggregate for road pavement may be used only on the surface layer of the road when used, and in such a case, the same excellent effects as described above can be obtained. . Further, in such a sintered artificial aggregate for road pavement, one having a size according to the form of use is used, but one having an average particle size of about 3 to 20 mm is generally used. Will be done.

As described above, by adopting such a manufacturing method, a high-quality sintered artificial aggregate for road pavement excellent in mechanical strength and wear resistance can be industrially advantageously obtained. It becomes.

[0028]

EXAMPLES Hereinafter, some examples of the present invention will be described to clarify the present invention more specifically. However, the present invention imposes some restrictions by the description of such examples. It goes without saying that you don't receive anything. In addition, the present invention, in addition to the following examples, in addition to the above specific description, various modifications based on the knowledge of those skilled in the art, unless departing from the spirit of the present invention,
It should be understood that modifications, improvements and the like can be made.

First, predetermined amounts of commercially available calcined alumina, kaolin, and magnesium hydroxide were prepared as Al ₂ O ₃ source material, SiO ₂ source material, and MgO source material. Then, they were mixed in different amounts to obtain eight kinds of compounds. Among these compounds, those having a composition such that the theoretical chemical composition after sintering is within the scope of the present invention are referred to as Compounds A to D, respectively, and the theoretical chemical composition after sintering. Were mixed with each of the above-mentioned raw materials so as to fall outside the range specified in the present invention, respectively, and were designated as compounds E to H, respectively. Furthermore, for comparison, natural crushed stones of hard sandstone and limestone were used, and these were designated as natural aggregate 1 and natural aggregate 2, respectively. The theoretical chemical compositions of the compounds A to H after sintering and the chemical compositions of the natural aggregates 1 and 2 are shown in Table 1 below. The chemical compositions of the natural aggregates 1 and 2 were analyzed by X-ray fluorescence analysis.

[0030]

[Table 1]

Next, each of the compounds A to E was charged into a ball mill, and water was further added.
Grinding and mixing were carried out by a wet method until the thickness was reduced to not more than 00 μm to obtain each slurry. Subsequently, the thus obtained slurry was dehydrated by a filter press, and then subjected to granulation using an auger machine to obtain a pellet-shaped granulated product. Then, after drying these granulated products, each was fired at a firing temperature shown in Table 2 in a gas furnace for 1 hour.

[0032]

[Table 2]

Thus, eight types of sintered bodies having a chemical composition within the specified range of the present invention or outside the specified range were obtained. Then, among them, the blends A to D and H were sintered at a temperature within the range specified in the present invention, and the sintered bodies obtained as Examples 1 to 4 and Comparative Example 4, respectively. In addition, the sintered bodies obtained by firing the compounds EG at a temperature outside the specified range of the present invention were Comparative Examples 1 to 3, respectively. In addition,
Comparative Examples 1 to 4 have chemical compositions outside the specified range of the present invention.

Subsequently, the sintered bodies thus obtained, Examples 1-4 and Comparative Examples 1-4, and the natural aggregates 1-2,
Each physical property, that is, apparent porosity, bulk specific gravity, apparent specific gravity,
The water absorption was measured, respectively. The results are shown in Table 3 below. Note that the measurement of these physical properties was conducted by the Japan Society for the Promotion of Science, 124th Committee, Examination Method Subcommittee. The measurement was carried out according to "Magnesia clinker measurement method".

[0035]

[Table 3]

As is evident from Table 3, it has the chemical composition defined in the present invention and is 1700.
In Examples 1-4 fired at a temperature of at least ℃,
All of them have an apparent porosity of about 1.0%, and have a very dense structure. On the contrary,
Having a chemical composition outside the specified range of the present invention, and 1700 ° C.
In Comparative Examples 2 and 3 fired at a lower temperature, the apparent porosity was 8.5% and 9.0%. Densification,
What can not be done effectively is the result shown.

Next, in order to examine the mechanical strength of these sintered bodies and natural aggregates, the following tests were performed. That is, first, Examples 1-4, Comparative Examples 1-4, natural aggregates 1
2 were each crushed to obtain a crushed product, and the obtained crushed product was sized according to a conventional method so as to have a particle size distribution of 9.5 to 8.0 mm. Next, 200 g of each of the crushed particles thus sized was weighed, and 50 mmφ × 14
Then, they were put into a 0 mmh container, and then they were each crushed by applying a pressure of 300 kg / cm ^{2 with} an Amsler pressure tester. And after such crushing,
Each particle size distribution was measured. The results are shown in Table 4 below.
It was shown to.

[0038]

[Table 4]

As is evident from the results in Table 4, in Examples 1 to 4 according to the present invention, even after crushing with an Amsler tester, particles having a particle size of 9.5 to 6.7 mm Particles occupying 70% or more of the whole and having a particle size of 2.8 mm or less are extremely small at about 3.0 to 9.0%. On the other hand, in Comparative Examples 1 to 4 and natural aggregates 1 and 2 having a chemical composition outside the scope of the present invention, 9.5 was obtained.
The relatively crushed particles having a particle size of ~ 6.7 mm and having a relatively small degree of crushing are as small as about 60% or 40% or less, and conversely, particles having a particle size of 2.8 mm or less are crushed. The size of the large particles is 12% or more in each case, and exceeds 30% in Comparative Example 2 and the natural aggregates 1 and 2. That is, it has been proved that the sintered artificial aggregate for road pavement according to the present invention has extremely excellent mechanical strength as compared with natural crushed stone and the like.

Subsequently, the following tests were conducted to examine the wear resistance of these sintered bodies and natural aggregates.
That is, first, Examples 1-4, Comparative Examples 1-4, and natural aggregate 1
To 2 were each crushed to obtain a crushed product, and the obtained crushed product was sized according to a conventional method so as to have a particle size distribution of 15.0 to 12.7 mm. Next, 2600 g of each of the crushed particles thus sized was weighed and charged into a pot mill having an internal capacity of 4500 ml, and further poured thereinto with 1200 ml of pure water to promote abrasion of the crushed particles. Then, 2250 g of alumina particles sized to a range of 1.18 to 0.60 mm were charged. And
Thereafter, the pot mills were rotated at 55 rpm for one week, and then the crushed particles were taken out of each pot mill and sieved to separate particles having a particle size of 12.7 mm or more from particles having a particle size of 12.7 mm or more. Separately, only the weight of the particles having a particle diameter of 12.7 mm or more was measured.
Then, the measured value is calculated by the following formula: [2600 (weight before test)]
-Weight (measured value) of particles having a particle size of 12.7 mm or more after test] / 2600 (weight before test) x 100, that is, the value obtained by substituting into 100, that is, the total weight of the crushed particles subjected to the test. The ratio of the weight of the crushed particles that became less than 12.7 mm due to the abrasion in the test to the abrasion rate was defined as the abrasion rate, and their abrasion resistance was evaluated. The wear rates of the respective crushed particles thus obtained are shown in Table 5 below.

[0041]

[Table 5]

As is apparent from Table 5, the wear rates of the natural aggregates 1 and 2 are about 30%, and the wear rates of the sintered bodies of Comparative Examples 1 to 4 are 22.4 to 25.1%. On the other hand, the wear rates of Examples 1 to 4 are clearly low values of 17.3 to 19.4%. This indicates that the sintered artificial aggregate according to the present invention is remarkably excellent in abrasion resistance as compared with the others.

[0043]

As is apparent from the above description, the sintered artificial aggregate for road pavement according to the present invention has a predetermined chemical composition and an apparent porosity of 8.0% or less. Since it has a dense structure, both mechanical strength and abrasion resistance can be dramatically improved as compared with conventional road pavement aggregates using natural crushed stone. That was it.

Therefore, by using such a sintered artificial aggregate for road pavement, the repair cycle of the road can be advantageously extended, and the cost and labor burden spent on the maintenance and management of the road can be increased. Therefore, the damage caused by dust generated by shaving off the road surface can be reduced as much as possible.

According to the method of the present invention, the sintered artificial aggregate for road pavement having the above-mentioned excellent characteristics can be industrially produced in large quantities with stable quality.

Continuation of front page (56) References JP-A-58-130157 (JP, A) JP-A-56-140077 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 35 / 00-35/22

Claims (2)

(57) [Claims] 1. An Al ₂ O ₃ source material, a SiO ₂ source material and M
It is obtained by sintering the granulated mixture with the gO source material.
An aggregate having an average particle size of 3 to 20 mm, wherein Al ₂ O
₃ 60 wt% or more, the SiO ₂ 0 to 40 wt%, and MgO and containing 0 to 5 wt%, and the total amount of the inevitable impurities resulting from the their raw materials thereof such that 100 wt% It has a chemical composition and an apparent porosity of 8.
Have a dense structure is less than 0%, further from 9.5 to 8.0
According to Amsler testing machine for particle size distribution of mm
Occupation of particles having a particle size of 9.5 to 6.7 mm after the crushing test
A sintered artificial aggregate for road pavement, characterized in that the ratio is 70% or more . _{2. An} aluminum oxide or aluminum oxide source is used as an Al ₂ O ₃ source material, silica or kaolin is used as an SiO ₂ source material, and magnesium hydroxide or magnesium oxide is used as an MgO source material. , Al ₂ O ₃ at 60% by weight or more and SiO ₂ at 0%
The raw materials are blended such that they contain -40% by weight and 0-5% by weight of MgO, and the total amount of them and unavoidable impurities derived from the raw materials is 100% by weight. The resulting formulation has an average particle size of 300μ.
m, pulverize, mix and granulate
To obtain a granulated product having an average particle size of 5 to 50 mm.
A method for producing a sintered artificial aggregate for road pavement, comprising firing at a temperature of 0C to 1900C .