JP3321152B1 - How to recycle construction sludge - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a construction sludge recycling method capable of regenerating construction sludge discharged as a result of excavation work related to construction work as a reclaimed crusher run or reclaimed grain size crushed stone that can be used as a roadbed material. . SOLUTION: A dewatering cake obtained by dewatering construction sludge is granulated by adding a solidifying agent made of cement, water and an additive and kneading the resulting granulated material. After curing, drying, and mixing the granulated material having a predetermined particle size range obtained by classifying the granules after drying is mixed with a crushed material having a predetermined particle size range obtained by crushing a concrete shell and then classifying it. Thus, a method for recycling construction sludge, characterized in that a reclaimed crusher oran and / or a reclaimed particle size adjusted crushed stone is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling construction sludge, and more particularly, to an effective method for recycling construction sludge which makes it possible to reuse construction sludge as a roadbed material.

[0002]

2. Description of the Related Art Construction sludge composed of fine particles containing a large amount of water, which is discharged during excavation work related to construction work, is treated as industrial waste, and conventionally discharged construction sludge is dewatered. After reducing the water content, it was landfilled. However, it is becoming more difficult every year to secure landfill disposal sites, especially in metropolitan areas where construction sludge discharges are high.
It had to be transported to a distant disposal site, resulting in higher processing costs. Therefore, in recent years, attempts have been made to recycle construction sludge as a recycled resource by mixing and solidifying cement, quicklime and the like with construction sludge. However, the recycled material thus obtained is
It can only be used for backfill materials and fills,
Because of its limited use and low utility value, it was not necessarily an effective recycling method for treating the huge amount of construction sludge discharged.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to regenerate construction sludge discharged as a result of excavation work related to construction work as a reclaimed crusher run or reclaimed material that can be used as a roadbed material. It is an object of the present invention to provide a method for recycling construction sludge that can be regenerated as crushed stone.

[0004]

According to the present invention, in order to solve the above-mentioned problems, in the invention according to claim 1, a solidifying agent made of cement, water and slag are added to a dewatered cake obtained by dewatering construction sludge. Granulated by adding and kneading, after drying the obtained granules in water for a certain period of time, drying, and granulating the granules in a predetermined particle size range obtained by classifying the granules after drying, reproducing by mixing crushed material having a predetermined particle size range obtained by classifying after crushing the concrete shell crusher run and / or to obtain a reproduction control granularity crushed stone, the predetermined particle size
Granules larger than the range are broken together with the concrete shell.
Crushed to a granulated product within the specified particle size range,
A recycling method for construction sludge, characterized in that the lower small-sized granules are recovered as reclaimed sand .

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a construction sludge recycling method according to the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing a preferred embodiment of the construction sludge recycling method according to the present invention. The type of construction sludge used as a raw material in the present invention is not particularly limited,
Muddy sludge discharged by muddy water shield method, continuous underground wall method, earth drill method, etc., muddy sludge discharged by mud pressure shield method, earth drill method, etc., high-pressure jet stirring method, soil cement wall method, etc. Any of the self-hardening sludge discharged by the method can be used.

[0006] These construction sludges are first subjected to a dehydration treatment to form dewatered cakes. When dehydrating,
A device used for ordinary sludge dewatering treatment can be used, and for example, a vacuum filter, a pressure filter, a gravity filter, and the like can be used. Further, in the case of muddy sludge which is difficult to be mechanically dewatered, a dewatered cake may be obtained by drying in the sun. At the time of this dehydration treatment, if unnecessary substances such as gravel are mixed in the sludge, the gravel is removed by a crusher.

Next, the dewatered cake obtained by the dehydration treatment is granulated by adding a solidifying agent, water and additives and kneading them. In the present invention, cement is used as a solidifying material, and slag is used as an additive. The kneading process is performed by charging the dewatered cake, cement, water, and slag to the granulator.
First, the dehydrated cake is put into the granulator, the weight is measured by the measuring mixer, and when the input weight reaches the set value, a predetermined amount of cement, water, and slag are automatically added so as to be further added. Is done. As the granulator, any of known granulators used for sludge granulation can be suitably used, for example, a tornado fin-type granulator having a spiral stirring blade in a cylinder. Machine or the like can be used. The kneading process by this granulator is performed, for example, for about 3 to 6 minutes, and as a result, the sludge introduced increases its particle size,
It is sequentially taken out from the belt conveyor as a granular product (granulated material).

[0008] The product obtained by the kneading treatment by the granulator is cured in water in the pool for a certain period of time, for example, about one week. This curing in water for a certain period of time allows the cement incorporated as a solidifying material to absorb water, thereby improving the strength of the product. The product that has been cured for a certain period of time is then naturally dried (air-dried) for about one day, and the contained water is blown off.

The product after drying is classified by a classifier according to a predetermined particle size. As the classifier, for example, a vibration sieve is used. In this vibrating sieving machine, the input product first has a component exceeding 40 mm in particle size and 40 m
m or less, and then the components of 40 mm or less are further separated into components having a plurality of particle size ranges. The particle size range of this separation is, for example, 0 to 3 mm, 3 to 10 mm,
Although it is set to 10 to 25 mm and 25 to 40 mm, the particle size range to be separated is not particularly limited to this size, and each particle size range may be differentiated for separation. And
Among the components having a particle size of 40 mm or less classified into a plurality of particle size ranges, the component having the smallest particle size (the component having a size of 0 to 3 mm in the above example) is recovered as recycled sand, and the other components are recycled crusher run as described later. And it is used for the production of crushed stone with adjusted regenerated particle size. Here, the reason that the component having the smallest particle size is not used for the production of the reclaimed crusher ore and the regenerated particle size adjusted crushed stone is that if such a small-diameter component is used, the particle size distribution as the regenerated crushed ore and the regenerated particle size adjusted crushed stone is not satisfied This is because the possibility is high.

[0010] The present invention provides a reclaimed crusher-run and a reclaimed particle size-adjusted crushed stone by mixing a product from the construction sludge obtained in this way with a regenerated aggregate obtained from a concrete shell without using it as a regenerated material as it is. The recycled aggregate mixed with the product from the construction sludge can be obtained, for example, as follows.

First, concrete husks discharged by the demolition of a building are firstly crushed by a primary crushing facility such as a jaw crusher, and then secondary crushed by a secondary crushing facility including an impact crusher such as an impeller. Thereby, the particle size is reduced to 40 mm or less. Here, among the products from the above-mentioned construction sludge, the components exceeding 40 mm are supplied to the secondary crushing equipment and crushed, thereby reducing the amount of the components.
mm or less.

[0012] The product from the concrete shell and the construction sludge whose size is reduced to 40 mm or less by the secondary crushing equipment is classified according to a predetermined particle size by a classifier such as a vibrating sieve. This classification is performed so as to have the same particle size range as the classification of the product from the construction sludge described above.
It is separated into four components of 10 mm, 10 to 25 mm, and 25 to 40 mm. In FIG. 1, the components of 0 to 3 mm are regenerated sand, 3 to 10 mm, 10 to 25 mm, 25 to 40 mm.
Is expressed as recycled crushed stone.

The four components obtained by the classification are 3 to 10 mm, 10 to 2
It is mixed with three components of 5 mm, 25 to 40 mm. By performing such mixing, a reclaimed crusher orchid (RC-40) usable as a lower subgrade material and a reclaimed grain size crushed stone (RM-30) usable as an upper subgrade material
Can be obtained.

As described above, the present invention does not use the product from construction sludge as it is as a recycled resource.
By mixing with recycled aggregate obtained from concrete shells, it is possible to obtain recycled resources (recycled roadbed materials) with higher utility value.

[0015]

Test Examples Hereinafter, the effects of the present invention will be clarified by showing test results on products from construction sludge obtained by the method according to the present invention and finally obtained recycled aggregate.

1) Sieving test The construction sludge before granulation (before the kneading step) by a granulator (hereinafter referred to as “sludge”)
Both the sludge or construction sludge) and the product after granulation (after the kneading step) (hereinafter, referred to as granulated material) were sieved to examine the particle size distribution. The test method was performed in accordance with "Soil grain size test" (JISA 1204). The test results are shown in Table 1 and FIG.

[Table 1] From Table 1 and FIG. 2, it can be seen that, through the kneading step, the fine particles of the sludge are granulated, and the particle size distribution has changed to the properties of large-size gravels and sand. This is considered to be due to the coagulation action of the granules due to the solidification of the cement.

2) Water permeability test A water permeability test was performed on both the construction sludge and the granulated material. The test method is “Soil permeability test (variable water level)” (JIS A 12
18), "Permeability test of soil (constant water level)" (JIS A 1218) was performed, and the compaction of the test piece was performed with water. The test results are shown in Table 2 and the hydraulic conductivity for each soil type is shown in FIG.

[Table 2] As is clear from Table 2 and FIG. 3, the sludge had a water permeability equivalent to that of fine sand or silt, whereas the granulated material was equivalent to sand. This indicates that the construction sludge was improved to have good water permeability by the method of the present invention.

3) Specific gravity and water absorption test The specific gravity and water absorption of the granulated product were measured. The test method was based on “Specific gravity and water absorption test of fine aggregate” (JIS A 1109). Table 3 shows the test results.

[Table 3] As can be seen from Table 3, the granulated product had a high water absorption of 27.11%.

4) Abrasion weight loss test Abrasion weight loss test was carried out to examine whether the granulated product did not become finely divided during loading and spreading. The test method was as follows: 7 days after production, using a 2.5 to 5 mm particle size component as a sample, "Abrasion test of coarse aggregate by Los Angeles tester"
(JIS A 1121). Note that the steps of washing and drying were omitted because curing conditions might change. Table 4 shows the test results.

[Table 4] As shown in Table 4, the abrasion loss of the granulated material was 25.6%
Met. Since the recycled aggregate has a grinding loss of 50% or less, it is considered that the granulated material has resistance to the grinding that can be used as the recycled aggregate and is hard to be granulated.

5) Dissolution test In order to confirm the safety of the granules, a dissolution test of the granules was performed. The test method was carried out using a sample on the 7th day after the production in accordance with the “test method for metals and the like contained in industrial waste”. Table 5 shows the test results. "Reference value" in the table means
Shows the numerical values stipulated in the "Prime Minister's Ordinance for Decision Criteria for Industrial Waste Including Metals, etc."

[Table 5] As shown in Table 5, the granulated material satisfied all the reference values.

6) Cone index According to the “Construction waste treatment guidelines”, the cone index of sludge is 200 kN.
/ M ² or less. Therefore, the strength of the granulated material was examined. The test method is "cone index test of compacted soil" (JGS
0716, 25 times / 3 layers). Table 6 shows the test results.
Table 7 shows the soil classification criteria.

[Table 6]

[Table 7] From the results shown in Tables 6 and 7, the cone index of the granulated product exceeds the standard value of the Type II improved soil, and because it is in the form of sand and gravel, it is considered to be a Type 1 improved soil. Can be

7) CBR test A CBR test is performed on RC-40 obtained by mixing the granulated material with recycled aggregate obtained from a concrete shell (obtained according to the flowchart of FIG. 1) and adjusting the particle size. Was. The test method was based on a "compacting test" (JIS A1210) and a "modified CBR test" (JIS A1211 pavement manual). The test results are shown in Table 8, and the standard values are shown in Table 9.

[Table 8]

[Table 9] From the results shown in Tables 8 and 9, the standard value of RC-40 was also R
It was found that the standard value of M was also satisfied. From this, it can be said that the recycled aggregate as the final product obtained by the method according to the present invention can be sufficiently used as a roadbed material.

[0023]

As described above, the present invention provides a dewatered cake obtained by dewatering construction sludge, adding a solidifying agent made of cement, water and slag , and kneading the resulting granulated granules. After curing the granulated material in water for a certain period of time and drying, the granulated material having a predetermined particle size range obtained by classifying the granulated material after drying is obtained by crushing a concrete shell and then classifying the granulated material. A method of recycling construction sludge characterized by obtaining reclaimed crusher oran and / or regenerated crushed stone by mixing with a crushed material having a predetermined grain size range, and a part of the sludge is conventionally reused as backfill material or embankment. Construction sludge that has only been used can be reused as a roadbed material with higher utility value, which can greatly contribute to recycling of construction sludge.

The present invention further provides a granulated material having a diameter larger than the predetermined particle size range together with the concrete shell to form a granulated material having a predetermined particle size range. Since this is a method of recycling construction sludge characterized by being recovered as sand, it is possible to increase the processing efficiency and to improve the quality of finally obtained recycled aggregate.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a preferred embodiment of a method for recycling construction sludge according to the present invention.

FIG. 2 is a graph showing the results of a sieving test.

FIG. 3 is a diagram showing the hydraulic conductivity for each type of soil.

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 11/00-11/20 B09B 3/00 C04B 18/04

Claims (1)

(57) [Claims] 1. A dewatered cake obtained by dewatering construction sludge is granulated by adding a solidifying agent made of cement, water and slag , and kneading the granulated product. After curing, drying, and mixing the granulated material having a predetermined particle size range obtained by classifying the granules after drying is mixed with a crushed material having a predetermined particle size range obtained by crushing a concrete shell and then classifying it. As a result, a reclaimed crusher oran and / or a reclaimed particle size-adjusted crushed stone is obtained, and a reclaimed crushed stone having a diameter larger than the predetermined particle size range is obtained.
The granules are crushed together with the concrete shell to a specified particle size.
Granulated material within the specified range, and a small-sized
A method for recycling construction sludge, which is recovered as recycled sand .