JPH0135786B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the plasticity of crushed stone waste containing fine particles such as clay and silt and having a high consistency. In the process of open-pit mining of rock and crushing it to produce crushed stone, in order to produce a product with excellent strength and other properties, crushed stone waste, usually called zuri, containing topsoil, soft stone, etc., and high-quality crushed stone are combined. It is essential to separate the crushed stone from rocks and dispose of this crushed stone waste. This type of crushed stone waste has a high consistency because it contains many fine particles such as clay, and when the moisture content increases, it becomes plasticized and becomes like a highly plasticized material or fluid, and its supporting capacity is significantly reduced, so it is not suitable for road use. It was also difficult to use it as a civil engineering material for building land, etc., and it required a great deal of cost and labor to dispose of it. In other words, in order to improve the above-mentioned properties, consideration must be given to waste disposal, such as mixing in a large amount of lump rock, and as a result, the amount of waste to be disposed of is increasing, and it is necessary to build dams in valleys and other places for sedimentation treatment. is common and is a cause of pressure on the profitability of the stone crushing industry. Conventional methods for using such crushed stone waste include physically separating and removing the fine particles, such as washing with water to remove fine particles such as clay and silt, and drying the crushed stone waste to remove fine particles. There are methods such as sieving the fraction. The former requires equipment and processing costs to treat the contaminated water containing fine particles used for washing, as well as rising costs.
The reality is that it is difficult to dispose of fine clay particles with high moisture content recovered from polluted water and to dispose of them. The latter method is not economical because it requires a huge amount of thermal energy and also requires the cost of collecting dust to prevent the dry dust from scattering. Therefore, most of the crushed stone waste is disposed of in a time-consuming manner, and it has been desired to utilize it effectively at low cost. In view of the above-mentioned circumstances, the present inventors have attempted to improve the plasticity of these crushed stone chips using a simple method so that they can be used as sub-base road materials for roads, etc., or as civil engineering materials such as materials for building land. Various studies were conducted on the addition of lime, cement, etc. As a result, by mixing a binder whose main component is cement and an appropriate amount of water and curing it naturally for more than 12 hours, the properties of fine particles such as clay contained in crushed stone waste are changed, and crushed stone waste is We succeeded in completely improving the plasticity of the material and converting it into a material with greater supporting capacity. An object of the present invention is to improve the properties of highly consistent crushed stone waste, thereby contributing to the utilization of resources. The gist of the present invention to achieve the above object is that 100 parts by weight of an anhydrous base of crushed stone waste containing fine particles and high consistency, 2 to 4 parts by weight of a binder mainly composed of Portland cement, and water.
10 to 15 parts by weight of crushed stone chips, kneaded, and naturally cured in the open air for 12 hours or more. The consistency of a soil material is a term that expresses the degree of difficulty in deforming the soil, and for soil materials that have plasticity, the consistency increases as the water content increases. As the water content ratio decreases, the state changes from liquid to plastic, from plastic to semisolid, and from semisolid to solid. The water content ratio at the boundary of each state is called the liquid limit, plastic limit, and shrinkage limit, respectively. I'm here. The test to determine the liquid limit and plastic limit of soil is
JISA1205 "Soil liquid limit test method",
It is specified in JISA1206 "Soil plasticity limit test method". If the liquid limit and/or plastic limit cannot be determined according to the method prescribed by JIS,
or if the liquid limit is less than the plastic limit, NP
(non-Plastic), and such materials do not increase in consistency even when hydrated. Crushed stone waste containing fine particles such as clay often has a moisture content of 8% to 10%, except during or after rain.
Also, materials that have been naturally deposited for several weeks or more usually have a moisture content of this level. In the present invention, such crushed stone waste is first sieved to a certain particle size, for example, 20 mm or less, and the water content is measured, and then the anhydrous base of this crushed stone waste is
Add 2 to 4 parts by weight of a binder whose main component is cement to 100 parts by weight, adjust the water content so that the total water content is 10 to 15 parts by weight, and quickly knead with a kneader. The binder containing Portland cement as a main component may be ordinary Portland cement alone, or may contain a small amount of lime, fly ash, etc., or a dispersant may be added thereto. The binder of the present invention coarsens fine particles of several micrometers to several tens of micrometers in crushed stone waste to several tens of micrometers to several hundred micrometers, thereby significantly reducing the number of fine particles that cause plasticity. In this respect, the present invention is fundamentally different from "soil cement," which produces concrete with a poor mix to form roadbeds and roadbeds. "Soil Cement"
It is a material made by adding about 2 to 6% cement and appropriate water depending on the material to on-site soil or crushed stone with a nearly continuous particle size whose particle size distribution has been properly adjusted to increase the compaction density. Immediately after kneading, the mixture is compacted and consolidated to integrate it into roadbeds and roadbeds. In contrast, the present invention coarsens only the fine powder of crushed stone chips with a large consistency, and preferably for 12 hours or more after kneading.
It is naturally cured in the outside air for 24 to 48 hours.
The binder does not solidify the entire material into a large mass. That is, in the material of the present invention, even if it is expanded and consolidated after natural curing, the binder has no ability to agglomerate the entire material, and the material only loses its plasticity. The amount of binder added is based on anhydrous crushed stone waste.
If the amount is less than 2 parts by weight per 100 parts by weight, the plasticizing properties of crushed stone chips cannot be sufficiently improved.
On the other hand, if more than 4 parts by weight is added, the material will partially solidify and form large lumps during the natural curing period in the open air, which is undesirable, and the price will rise, making it uneconomical. Water content is 10 parts by weight of crushed stone waste anhydrous base.
~15 parts by weight. Normally, as above, crushed stone waste is 8
% to 10% of water (approximately 9 to 11 parts by weight of water per 100 parts by weight of crushed stone waste on an anhydrous basis), so in many cases there is no need to add water during kneading, but 1 to 2 parts by weight. It is often preferable to add water to achieve uniform kneading. If the water content is less than 10 parts by weight based on the anhydrous crushed stone waste, the effect of coarsening the fine particles of the binder will not be sufficient, and if it exceeds 15 parts by weight, the hydration of the binder will progress and the material will become agglomerated. Undesirable. The present invention makes it possible to improve the plasticizing properties of crushed stone waste, which conventionally had to be disposed of, and makes it possible to use it as a civil engineering material with performance comparable to crusher run, for example, as a sub-base course material for roads. Ta. Next, the effects of the present invention will be explained in more detail with reference to Examples. Example Crushed stone waste 1 separated from raw stone at a crushing factory was improved in plasticity according to the process shown in FIG. The crushed stone waste was sieved through a sieve 2 with a mesh size of 20 mm, and the undersize 3 (particle size 20 to 0 mm) was used as a raw material. Table 1 shows the water content ratio, particle size, liquid limit, plastic limit, plastic index, etc. of this raw material 3. This raw material has a liquid limit of 31.0%, a plastic limit of 21.0%, a plasticity index of 10.0,
Furthermore, the CBR is 29.8%, making it difficult to use as a civil engineering material. 100 tons of this raw material crushed stone waste is quantitatively discharged from the hopper 4 using a quantitative discharge feeder 5 at a constant discharge rate, and a total amount of 2 tons of ordinary Portland cement is evenly distributed to this crushed stone waste from a cement silo 6 by a quantitative feeder 7. The mixture was supplied as a binder, and a total of 0.5 tons of water was added evenly through a control valve 9 by a pump 8, and the mixture was kneaded in a paddle mixer 10 having a capacity of 200 tons/hour. Measurement of raw material moisture and control of flow rate were carried out by a control device 11 according to the system shown by broken lines in FIG. The amount of binder mixed and the amount of water in this example are: 2.3 parts by weight of cement, 13.9 parts by weight of water content of the raw material, 0.6 parts by weight of water, and 14.5 parts by weight of total water per 100 parts by weight of the raw material crushed stone waste on an anhydrous basis. It was hot. After kneading the above-mentioned materials, they were conveyed to a storage area 13 by a conveyor 12, piled up, and naturally cured for 24 hours.
The average temperature at this time was 22℃. The moisture content, particle size, liquid limit, plasticity limit, and plasticity index of the plasticity improving material after 24 hours of natural curing treatment were
Also listed in the table. As is clear from Table 1, the plastic limit and liquid limit of crushed stone waste disappear by the method of the present invention, and the NP
(Non-Plastic), and the plasticity of the raw material was completely improved. In addition, since the water content after plasticity improvement was 10 parts by weight based on the anhydrous base material, it is thought that 4.5 parts by weight was involved in the binder reaction. The particle sizes of this raw material crushed stone waste and the improved material are shown on a logarithmic scale in Figure 2. 20 is the raw material crushed stone waste, and 21 is the material after treatment. From FIG. 2, it is clearly recognized that the particle size of fine particles in the clay, silt, and fine sand regions is becoming coarser. In addition, sieve the part of these samples with a particle size of 2 mm or less, take 100 g of air-dried sample, and add 25 g of tap water.
Fig. 3 shows how the precipitate settled when the sample was poured into a graduated cylinder along with 100ml of the precipitate, shaken for 1 minute, and then allowed to stand still. A is the raw crushed stone waste, b is the treated material. In a, a fine particle layer of 21 mm was generated on a coarse particle height of 33 mm, but in the treated material, a fine particle layer of only 4 mm was generated on a coarse particle height of 39 mm. It was clear that coarsening of the fine particles was achieved by the treatment of the present invention. Therefore, these also prove that the plasticity of crushed stone waste can be improved according to the present invention. Another effect of this plasticity improvement treatment method was that the CBR increased to over 110, making it a material with excellent performance as a road bed, roadbed material, etc. 【table】

[Brief explanation of drawings]

Fig. 1 is a process diagram of the treatment method of the present invention, Fig. 2 is a graph showing the particle size distribution of raw crushed stone waste and the material after the treatment of the present invention, and Fig. 3 is a graph showing the particle size distribution of the raw crushed stone waste and the material after the treatment of the present invention. FIG. 2 is a side view of a graduated cylinder showing the results of a sedimentation test. 1... crushed stone waste, 2... sieve, 3... undersize, 4... hopper, 5... quantitative discharge feeder,
6...Cement silo, 7...Quantitative supply device, 8
... Pump, 9 ... Control valve, 10 ... Paddle mixer, 11 ... Control device, 12 ... Conveyor, 1
3... Storage site, 20... Raw crushed stone waste, 21... Processing material according to the present invention.

Claims (1)

[Claims] 1 100 parts by weight of anhydrous base of crushed stone waste with high consistency including fine particles, 2 to 4 parts by weight of a binder mainly composed of Portland cement, and 10 parts by weight of water.
1. A method for improving the plasticity of crushed stone waste, characterized by adding ~15 parts by weight, kneading, and naturally curing in the open air for 12 hours or more.