JP6021059B2 - Paving material and paving method using the same - Google Patents

Description

  The present invention relates to a paving material mainly composed of soil and magnesium oxide and a paving method using the same. Specifically, the present invention relates to a pavement material mainly composed of pure sand soil and containing special magnesium oxide as a solidifying material, and a pavement method for achieving further effects.

There are many structures (rail tracks, etc.) laid in the railway site, but weeds are prone to hinder the visibility of the track tracks. There are methods such as herbicides and mowing to remove overgrown weeds, but herbicides are not desirable because they have concerns about adverse effects on residents and the natural environment along the lines, and the visibility is mainly maintained by mowing. .
However, since the route site is narrow and structures such as cables and wire maintenance facilities are installed, workability is poor. For this reason, accidents such as breakage of equipment and injury of workers sometimes occurred. Furthermore, since the mowing work is interrupted when the train passes, the actual work time is short and the cost is considerably high.
In order to suppress the growth of weeds, a method of solidifying the ground using a commercially available soil solidifying material has been developed. For example, Patent Document 1 discloses a method for constructing a weed reproduction preventing agent that contains magnesium oxide and an extender and reacts with water to harden, and a weed reproduction preventing layer that supplies the same agent to the ground, agitates the soil, and sprinkles water. It is disclosed.

JP 2003-47388 A

  However, since the weed reproduction inhibitor described in Patent Document 1 is mixed with soil on the site and applied, it is difficult to mix uniformly enough, and a bulking agent or the like must be added to improve uniformity. There is a problem. In addition, as described above, since it is necessary to perform the construction in a limited time during the passage of the train in a narrow area, (1) it can be easily constructed without using heavy equipment, etc., (2) in a short time (3) Easy installation and removal of track marks after construction, (4) No environmental impact (recyclability, high alkali and heavy metal elution), ( 5) Maintenance after construction is not necessary (no need to sow herbicides, etc.) and all of these must be satisfied. In order to solve these problems, paving materials for narrow land (soil solidifying material, weed prevention material) are required. For example, a mixture of soil and magnesium oxide is known as having no environmental impact, but the strength of solidification with magnesium oxide is not sufficient, and there is a problem that solidification aids such as blast furnace slag must be used in combination. is there.

  The present invention has been made in view of the above problems, does not require a bulking agent, a solidification auxiliary material, etc., can be easily and quickly constructed without using heavy machinery, etc., and is easy to repair after construction. An object of the present invention is to provide a paving material that does not affect the environment and a paving method using the same.

  As a result of intensive studies to achieve the above object, the present inventors have previously mixed soil and magnesium oxide having excellent dispersibility into a pavement material, so that the soil and magnesium oxide particles are highly dispersed. In addition, the present inventors have found that a paving material excellent in environmental safety and excellent in strength can be obtained without adding blast furnace slag or the like with only magnesium oxide, and has been achieved. That is, the present invention relates to a pavement material characterized by being a mixture in which magnesium oxide having an average particle diameter of 1.0 to 10.0 μm and an average periclase crystallite diameter of 330 to 430 mm is mixed with soil.

  Further, the present invention has a pavement material leveling step of spreading the pavement material on the ground, and a solidification step of watering the ground where the pavement material is leveled to solidify the pavement material. It is related with the pavement method characterized by this.

  As described above, according to the present invention, it is not necessary to use a bulking agent or a solidification auxiliary material, and it can be easily and quickly constructed without using heavy machinery, etc., and it is easy to repair after construction and has an environmental impact. It is possible to provide a pavement material without a pavement and a pavement method using the pavement material.

  Magnesium oxide used in the present invention has an average particle size of 1.0 to 10.0 μm, and more preferably 1.0 to 5.0 μm. When the average particle size is 1.0 to 10.0 μm, it is finely dispersed in the soil. Thereby, intensity | strength can be expressed even with a small addition amount. When the average particle size is less than 1.0 μm, the cohesiveness of the particles becomes strong, so that the particles are not sufficiently dispersed when mixed with a mixer. When the average particle size exceeds 10.0 μm, the particles themselves are large, so the mixture with the soil In that case, the uniformity is inferior (the number of magnesium oxide particles contained in the same mass is small, and the distance between the particles becomes large).

  In addition, in the present invention, magnesium oxide needs moderate activity, and if the activity is too low, it takes time to develop strength, so the work in the route is limited, and if the activity is too high, it solidifies rapidly after watering. Causes problems in construction. In particular, since the pavement material of the present invention can be applied to a narrow area in a route, it is essential that the pavement material can be quickly constructed without using heavy machinery or the like, and that the strength capable of quickly working after construction can be expressed. Even if it is the commercially available light-burned magnesium which baked magnesite, and the magnesium oxide derived from a seawater method, said characteristic is not expressed with the thing whose activity is too high or too low. The activity of the magnesium oxide can be evaluated by the average periclase crystallite diameter. Magnesium oxide having the above characteristics has an average periclase crystallite diameter of 330 to 430 mm, and more preferably 350 to 400 mm.

The magnesium oxide used in the present invention preferably has a BET specific surface area of 5 to 12 m ² / g. The BET specific surface area is one of the indexes representing the reactivity of magnesium oxide, and if the BET specific surface area is smaller than 5 m ² / g, the solidification of the soil is delayed, which is not preferable. On the other hand, if the BET specific surface area is larger than 12 m ² / g, the hygroscopicity is increased and there is a problem in storage stability, which is not preferable.

  The magnesium oxide used in the present invention is not particularly limited, but is preferably magnesium oxide derived from seawater. Seawater-derived magnesium oxide means magnesium oxide obtained by baking magnesium hydroxide precipitated by adding slaked lime to seawater.

  In the present invention, the content of magnesium oxide in the pavement material is preferably in the range of 2 to 20% by mass and more preferably in the range of 3 to 15% by mass with respect to the total amount of the pavement material. If the content of magnesium oxide is less than 2% by mass, the solidification ability of the soil is lowered. On the other hand, if it is more than 20% by mass, besides the cost and color tone, the pH tends to increase, which is not preferable.

  In the present invention, the soil to be used is not particularly limited, and examples thereof include true sand soil, Kanto loam, Kuroboku soil, red soil, and shirasu soil. Magnesium oxide is said to solidify mainly by the pozzolanic reaction, and is compatible with soil containing amorphous silica. The pavement material preferably has a color that is easy to harmonize with surrounding soil. In view of the above, true sand is particularly preferably used among these. The particle size of the true sand is not particularly limited since it is a natural product, but any particle having a size of about 4 mm or less from which pebbles, seeds and the like are removed can be preferably used.

  In the present invention, the content of soil in the pavement material is preferably in the range of 80 to 98% by mass, more preferably in the range of 85 to 97% by mass in accordance with magnesium oxide, with respect to the total amount of the pavement material. is there. Moreover, 2% or less is preferable and, as for the moisture content of the soil at the time of being used for mixing with magnesium oxide, 0.01-1.0% is more preferable. It is difficult to dry the soil to less than 0.01% by the usual drying method. If it exceeds 2%, mixing with magnesium oxide is not performed sufficiently, or magnesium oxide is hydrated when storing paving materials. Since it becomes easy to do, it is not preferable. In order to adjust the moisture content, the soil is preferably dried. For drying the soil, an industrial drying apparatus such as a box-type dryer, a rotary dryer, a band dryer, or a fluidized bed dryer can be used as appropriate.

  The pavement material of the present invention can be produced, for example, by previously mixing the above components using a known mixing device such as a mixer. In the present invention, mixing in advance means that the material is mixed before the paving material is spread on the ground to be paved. By mixing in advance, it is not necessary to mix with soil at the site, and it is preferable because it can be applied easily in a short time. Moreover, the pavement material of the present invention may package a premixed mixture. Packaging a premixed mixture is preferable because it is easy to carry and can be applied more easily and in a short time. In addition, although it can also include the process of drying a mixture like the said soil drying after mixing, in order to prevent the water vapor | steam which generate | occur | produces by drying, a carbon dioxide gas, and magnesium oxide reacting, the moisture content of a mixture Is adjusted by the moisture content of the soil before mixing, and preferably does not include the drying step of the mixture.

Next, a pavement method using the pavement material of the present invention will be described. The pavement method of the present invention preferably has a root removal step of removing roots of weeds that breed on the ground to be paved. Furthermore, after the root removal step, when the pavement is uneven, a leveling step for forming a flat ground using a rake or a scoop may be provided. In addition, the leveling process can also perform rolling pressure etc., when a roadbed is soft. Moreover, in order to improve adhesiveness with a pavement material, about 5 L / m < ² > of water can be sprinkled on the leveled flat ground.

  The pavement method of the present invention includes a pavement material leveling step of spreading the pavement material on the ground after the leveling step. In the pavement material leveling step, it is preferable to first spread the pavement material as uniformly as possible, and then spread the leveled pavement material using a trowel or rake. Moreover, it is preferable that the leveled paving material has a thickness of about 1 to 7 cm from the ground. If it is less than 1 cm, peeling and cracking are likely to occur, which is not desirable. If it exceeds 7 cm, the sprayed water does not penetrate to the bottom, and it is difficult to form a uniform solidified layer. The pavement material of the present invention is mainly intended to prevent weeds from breeding, unlike soil hardeners intended to improve soft soil. In order to improve soft soil, it is necessary to solidify not only the surface layer of the ground but also to the deep part, but in the case of preventing weed reproduction, the pavement material of the present invention is spread on the ground surface and a relatively thin solidified layer is provided. Achieved.

  Since the pavement material of the present invention is premixed with magnesium oxide and soil, it is not necessary to mix the pavement material with the ground to be paved in the pavement material leveling step, and it is simple even without using heavy machinery or the like. It is possible to construct. In addition, in the case of normal application and treatment of a soil solidifying agent in the field, it is necessary to remove the seeds from the soil because the soil on the ground to be paved must be used, but the paving material of the present invention is made of magnesium oxide. Since soil and soil are mixed in advance, this is not always necessary, and rapid construction is possible.

The pavement method of the present invention has a solidification step of solidifying the pavement material by sprinkling water on the ground leveled with the pavement material after the pavement material leveling step. In the solidification step, the amount of water used for watering is preferably changed as appropriate depending on climatic conditions and the like, but usually, for example, about 15 to 20 L / m ² is preferable in the case of a thickness of 5 cm. Moreover, it is preferable to perform watering with a shower-like soft water quantity using a watering hose or a hose. After watering, the magnesium oxide in the paving material can be solidified satisfactorily by curing for one to two days. Since the paving material after solidification can effectively prevent weeds from growing, maintenance is not required, such as eliminating the need to spray a herbicide or the like on the paved ground.

  Since the pavement material of the present invention is a mixture of magnesium oxide and soil, there is no elution of high alkalis, heavy metals, etc., and magnesium oxide is generally used as a fertilizer and is therefore excellent in safety. Moreover, since the pavement material of the present invention does not require a solidification auxiliary material such as blast furnace slag or a bulking agent, the pavement material can be easily broken, and repair after construction is easy. Furthermore, the broken pavement material is excellent in recyclability because it can be used as soil having a fertilizer effect.

  The pavement method of the present invention can be easily applied in a short time without using heavy machinery, etc., and is particularly suitable for use in railway route sites, but is not limited thereto, and is a viewpoint of safety, recyclability, etc. It can be installed on any ground such as sidewalks, parks, residential areas, and graves.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, these do not limit the objective of this invention. First, the average particle diameter, the average periclase crystallite diameter, and the BET specific surface area of the magnesium oxide powder used in Examples and Comparative Examples were measured by the following methods.

[Average particle size]
Magnesium oxide powder was put into ethanol and subjected to ultrasonic dispersion treatment for 2 minutes, and then the particle size distribution was measured using a laser diffraction particle size distribution measuring device (Microtrack HRA manufactured by Nikkiso Co., Ltd.).

[Average periclase crystallite diameter]
Using an X-ray diffraction apparatus, the X-ray diffraction pattern of the (200) plane of magnesium oxide was measured under the conditions of a tube voltage of 40 kV and a tube current of 40 mA, and the average periclase crystallite was calculated from the half width using Scherrer's formula. The diameter was determined. A standard silicon powder for X-ray diffraction was used as a standard sample.

[BET specific surface area]
About 0.3 g of sample magnesium oxide powder is put into a sample filling cell of a BET specific surface area measuring apparatus (MONOCHROME manufactured by monosorb) and heated at a temperature of 200 ° C. for 15 minutes to remove adhered water of the magnesium oxide powder. , Measured by the BET one-point method.

[Workability]
The workability was evaluated as follows.
In accordance with JIS A 1101 concrete slump test method, prepared by adding 25 parts by mass of water to a pavement material (105 parts by mass in total) prepared by adding 5 parts by mass of magnesium oxide to 100 parts by mass of pure sand. The sample was packed in a slump cone (upper end inner diameter 100 mm, lower end inner diameter 200 mm, height 300 mm), and then the slump cone was pulled up and the fall at the center portion was measured to obtain a slump value.
A ratio S3 / S0 between the slump value (S0) measured immediately after filling the slump cone and the slump value (S3) measured after 3 hours passed after filling the slump cone, and 6 hours passed after filling the slump cone. The ratio S6 / S0 of the slump value (S6) measured later was obtained, and the reduction ratio of the slump value was used as an evaluation index for workability.

[Moisture percentage]
The moisture content was measured according to JIS K 0067 at a heating and drying temperature of 105 ° C.

[Magnesium oxide]
In Example 1 and Comparative Examples 1 and 2, baked magnesium hydroxide produced by the seawater method at different temperatures in a rotary kiln was used.
The comparative example 3 used the commercially available magnesium oxide which baked the magnesite from China, and the reference example 1 used what grind | pulverized the magnesium oxide of the comparative example 3 for 30 minutes with the ball mill.

Example 1
An average particle size of 2.9 μm, an average periclase crystallite size of 366 mm, and a BET specific surface area of 6.8 m ^{2 with} respect to 100 parts by mass of dry sand sand (water content: 0.34%) that has passed through a sieve with a mesh opening of 4 mm A pavement material was prepared by mixing 5 parts by mass of magnesium oxide / g. A specimen for a uniaxial compressive strength test was prepared by adding 12 parts by mass of water to 105 parts by mass of the pavement material. The specimen preparation method was prepared by mixing the pavement material and water with a soil mixer for 4 minutes and using a mold (cylindrical container) having a diameter of 5 cm and a height of 10 cm and a 1.5 kg rammer (weight). . The obtained mixture was divided into 4 layers in a mold (cylindrical container), and the first layer 10 times, the second layer 20 times, the third layer 20 times, the fourth layer 40 times, a total of 90 times, Rammer (Weight) was repeatedly dropped from a height of 30 cm to form a mixture into a cylindrical shape.
The molded cylindrical molded body was extracted from the mold, covered with a polyethylene film and sealed, and then cured in air for 7 days to obtain a specimen. The specimens were measured for uniaxial compressive strength by a method in accordance with JIS A 1216 “Soil Uniaxial Compression Test Method”.
As a result, the uniaxial compressive strength was 1.937 N / mm ² . Further, S3 / S0 indicating workability was 0.93, which was good.

(Comparative Example 1)
A uniaxial compressive strength test was performed in the same manner as in Example 1 except that magnesium oxide was changed to magnesium oxide having an average particle size of 3.1 μm, an average periclase crystallite size of 445 mm, and a BET specific surface area of 5.7 m ² / g. .
As a result, the uniaxial compressive strength was 1.209 N / mm ² . Further, S3 / S0 indicating workability was 0.91, which was good.

(Comparative Example 2)
A uniaxial compressive strength test was conducted in the same manner as in Example 1 except that the magnesium oxide was changed to magnesium oxide having an average particle size of 3.5 μm, an average periclase crystallite size of 302 mm, and a BET specific surface area of 19.8 m ² / g. .
As a result, the uniaxial compressive strength was 2.946 N / mm ² . Further, S3 / S0 indicating workability was 0.56, which was poor.

(Comparative Example 3)
A uniaxial compressive strength test was conducted in the same manner as in Example 1 except that the magnesium oxide was changed to magnesium oxide having an average particle diameter of 20.1 μm, an average periclase crystallite diameter of 473 mm, and a BET specific surface area of 17.5 m ² / g. .
As a result, the uniaxial compressive strength was 0.815 N / mm ² . Moreover, S3 / S0 which shows workability was 1.00 and was favorable.

(Reference Example 1)
A uniaxial compressive strength test was conducted in the same manner as in Example 1 except that magnesium oxide was changed to magnesium oxide having an average particle diameter of 3.2 μm, an average periclase crystallite diameter of 401 mm, and a BET specific surface area of 20.8 m ² / g. .
As a result, the uniaxial compressive strength was 1.401 N / mm ² . Moreover, S3 / S0 which shows workability was 1.00 and was favorable.

  Table 1 lists the results of evaluating the physical properties of magnesium oxide and the uniaxial compressive strength and workability of the specimen.

(Example 2)
Weeds were removed from the pavement area, and roots were removed to make the construction surface. Then, the same pavement material as that prepared in Example 1 was spread on the construction surface so as to have a thickness of 30 mm, and 20 L of water was sprayed per 1 m ^{2 of} the construction surface using a watering device. Observation was made after one month from the construction, but no grass was grown on the construction surface.

Claims (4)

Magnesium oxide having an average particle size of 1.0 to 10.0 μm, an average periclase crystallite size of 330 to 430 mm , a BET specific surface area of 5 to 12 m ² / g , and a soil having a moisture content of 0.01 to 2% , A pavement material characterized by being a mixture in which   The pavement material according to claim 1, wherein the soil is sand sand. A paving material leveling step of spreading the paving material according to claim 1 or 2 on the ground;
Watering the ground where the pavement material is spread and leveling, a solidification step of solidifying the pavement material;
A pavement method characterized by comprising: The pavement method according to claim 3 , further comprising a root removal step for removing roots of the weeds that propagate on the ground before the paving material spreading step.