JP2965460B2 - Method for producing solidified material mainly composed of construction sludge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidified product containing construction sludge as a main component and a method for producing the same, and more particularly to a cement-type solidified product which can be used for civil engineering and building materials and has reduced alkalinity, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, sludge containing a large amount of water generated by excavation is treated as industrial waste. Processing construction sludge corresponding to the waste to absorb moisture by adding lime solidifying agent and a polymer-based water-absorbing agent, such as cement, the extent of losing fluidity, solidifies to a degree with plasticity,
Only part of it is used as backfill material. Most of the rest was transported to landfills. The treated product obtained by using a generally used lime-based solidifying agent uses a large amount of the lime-based solidifying agent to maintain a certain strength or more. Since the lime-based solidifying agent is an alkaline substance, the solidified product after the treatment is also strongly alkaline.

[0003] If the solidified material having a strong alkalinity is used for landfill, civil engineering aggregate, etc., the environment of soil and water quality will be deteriorated. Therefore, the solidified material after treatment is restricted from being directly used for landfill, civil engineering aggregate, etc. due to restrictions such as environmental standards. In addition, construction sludge that has only been dewatered dries when left to stand, and fine soil dust may fly into the air when the wind blows, causing air pollution. If clay-like construction sludge or solidified material after treatment is left unused at the final disposal site, it has harmed the environment and has become a social problem. Conversely, it is possible to produce a nearly neutral solid that is weak in alkalinity and conforms to environmental standards. However, the solidified product has a drawback that incapable of holding the Ruhodo required strength is provided for use as building materials.

[0004] In general, not only solidified matter after treatment of construction sludge, solidified matter using a lime-based solidifying agent such as cement exhibits strong alkalinity. High-strength cement solids exhibit strong alkalinity, and as they approach neutrality, their strength decreases as they approach, and eventually loses their function. This is the so-called neutralization (carbonation) phenomenon of concrete. Therefore, when treating construction sludge, it is difficult to meet the two requirements, that is, strong ones and those that are near neutral due to environmental impact, and if it meets one of the requirements, It was effectively used only when it was good, and most were disposed of at the disposal site.

[0005]

SUMMARY OF THE INVENTION Environmental regulations and the like are becoming increasingly strict, and in the future there will be more stringent situations. In particular, groundwater pollution is regarded as a major problem, and some local governments have their own regulations, which limit the effective use of waste and the like. Therefore, the present invention aims to solve the above-described problems of the conventional example,
It is an object of the present invention to provide a solidified material mainly composed of construction sludge and a method for producing the same, which can obtain a cement solidified material having a certain degree of strength, which suppresses alkalinity, has no adverse effect on the environment, and has a wide range of versatility. Aim.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a cementitious solidifying agent, which is incorporated into a hydrated construction sludge, and a blending agent which penetrates the construction sludge and the solidifying agent to enhance their physical strength and enhance their chemical resistance. Acid and phosphoric acid as a neutralizing agent to suppress alkalinity
A method for producing a solidified product containing construction sludge as a main component, in which an appropriate amount of a drug as a main component is added, and these are mixed using a high-speed mixer and granulated to a particle size of up to about 10 mm while mixing. Further, the present invention, to the water-containing construction sludge, cement-based solidifying agent, adding an admixture to enhance the physical strength and chemical resistance of these construction sludge and solidifying agent to penetrate the,
While mixing these using a high-speed mixer, the maximum particle size is 1
After granulating to about 0 mm and curing the granulated material for a certain period , phosphoric acid is mainly used as a neutralizing agent to suppress alkalinity.
A method for producing a solidified product containing construction sludge as a main component, which is treated with a predetermined amount of a chemical as a component . Thus, the obtained solidified cement has a certain strength or more while having properties close to neutrality. Therefore, the construction sludge is widely used as a civil engineering material such as backfill soil, and can be further used as an artificial aggregate. The solidified cement will not be stuck in the dumping site or disposed of at the disposal site.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention solves the problem of the treatment of construction sludge with a lime-based solidifying agent, and achieves effective utilization. First, an outline of the invention will be described. Construction sludge containing water is generated at construction sites and civil engineering construction sites.
During excavation, excavated soil is excavated by groundwater, and excavated soil is subjected to water sprinkling to prevent the dust from diffusing to the outside, so that construction sludge rich in water is generated.
The construction sludge is obtained by removing the supernatant water from the milky liquid of the collected construction sludge. Construction sludge has a high moisture content, and its particles are as fine as 10 μm to 500 μm. Furthermore, bentonite sludge cannot be reused as it is because it is alkaline, etc., and most of the sludge is dewatered and disposed of. A lime-based solidifying agent is generally used as a method for the regeneration treatment. However, according to this method, the material exhibits strong alkalinity and is backfilled by various regulations in order to minimize the effect on the environment. Was not fully utilized.

Accordingly, the present invention has made it possible to maintain a certain strength or more while suppressing alkalinity even when a lime-based solidifying agent such as cement is used, and to expand its effective use. In order to maintain the strength of the solidified cement, a special admixture is added during the usual process of manufacturing the solidified cement,
Granulation was performed using a high-speed mixer, and treatment for neutralizing alkalinity was performed using a chemical containing phosphoric acid as a main component. According to this method, it was possible to produce a civil engineering material having a certain level of strength, which was suppressed in alkalinity and could not be achieved by conventional construction sludge treatment, from construction sludge.

[0009] The present invention relates to the use of an admixture for maintaining strength, granulation, and a phosphoric acid as a main component as a neutralizing agent in the production of a solidified cement. The use of a drug that does The use of the admixture produces a cement-based solid which is dense and resistant to chemical attack. The special admixture, Geodor, made in Denmark, which is mainly used this time, is an admixture that has an effect of evenly penetrating into the solidification target material, fully exerting the performance of cement, and producing a stronger solidified product. Has a proven track record.

First, a first experiment was conducted to prove that the admixture effectively acts on physical strength retention. Cement was kneaded with an aqueous solution of a neutralizing agent for suppressing alkalinity, and a so-called cement paste was allowed to stand for a predetermined time to be solidified, and a strength experiment was performed to compare with the solidified product (Table 1).
The results clearly show a difference in strength between the sample to which geodol was added and the sample without addition. Cement 100
Each sample (Nos. 113 and 114) obtained by adding only 15 ml and 20 ml of the neutralizing agent to g was in a state where it was fragile and collapsed. However, Geodor 10 in 100 g of cement
g, 20 g and the neutralizing agent in 20 ml, 20 ml (g,
%) Of each sample (No. 115, No. 1)
16) is solidified. Next, the amount of the neutralizing agent was increased, and 20 g of Gedol and 3 neutralizing agents were added to 100 g of the cement.
The sample (No. 117) to which 0 ml was added was also in a state similar to the sample (No. 114) in a state in which it was fragile and collapsed.

[0011]

[0012] Admixtures from this study demonstrated to act effectively on the strength retention, also in suppressing the alkaline
It can be understood that the strength is reduced when the amount of the wetting agent exceeds an appropriate value. It is expected that a similar effect can be obtained in a granulation test using a high-speed mixer described below. Regarding this admixture, according to the experiment of the inventor of the present application, according to the experiments of the present invention, a granulated material produced by a granulation test using a naphthalenesulfonic acid-based, ligninsulfonic acid-based high-performance water reducing agent,
Since the same strength as that of the granules using geodol was obtained, it is effective to use not only geodol and the above-mentioned admixtures but also other admixtures which exhibit chemical resistance and improve the strength.

Next, in order to prove that granulation and physical treatment have an effect of suppressing alkalinity, a second experiment was performed in comparison with non-granulation. Water is mixed with the cement by a mixer to form a cement paste, and the particle size is granulated to a maximum of about 10 mm to check whether alkalinity has been suppressed. The pH of the cement solidified by the cement paste thus obtained was measured by a third party laboratory. The following Measurement Certificate 1 was issued by a third party, inspected by a competent inspection laboratory.

Measurement certificate 1 Aug. 25, 1993 Tester: Nippon Inspection Co., Ltd. Tokyo Physical and Chemical Laboratory Test method: According to the Environment Agency Notification No. 13 Client: Nippon Chemitac Co., Ltd. Material: Granulated cement paste Analysis item: pH value Result: 8.10

The solidified cement produced with exactly the same composition had a strongly alkaline pH of 11.3 in a normal solidified product, whereas the granulated product had a pH of 8.1. This means that the hydration reaction of cement is promoted by granulation, and the unhydrated cement paste (the one obtained by kneading cement only with water), which is the largest cause of alkalinity, is reduced. In the neutralization treatment of the process, the penetration of the drug can be accelerated.

Finally, the neutralizing agent for suppressing alkalinity will be described. Various neutralizing agents can be considered, but in this experiment, mainly a phosphoric acid-based agent was used.
Phosphoric acid-based chemicals react with Ca and Na components in unhydrated cement paste that exhibits alkalinity to form insoluble compounds, or even more water-soluble compounds that are more neutral. . The amount used depends on the amount of alkali content of the target substance and the amount of cement used for solidification, but in general construction sludge, excluding bentonite sludge mainly containing sodium, it is generally 1 to 1.5 times the weight of the target sludge.
% Based. The method of mixing the neutralizing agent includes a method used when mixing and granulating using a high-speed mixer, and a method of mixing after granulation and curing, and it is possible to select either depending on the required strength. . The above three points, namely, high density by mixing with an admixture, neutralization treatment by mixing with a neutralizing agent , weak alkalinization by granulation, while maintaining strength and having properties closer to neutrality. It becomes a cement-based solid.

[0017]

Embodiment 1 About 8% of cement (weight ratio of object) is added as a cement-based solidifying agent to construction sludge generated by excavation work and the like, and is used as an admixture having an effect of improving strength and improving chemical resistance. 2% (weight ratio of material) is added, and the mixture is kneaded and granulated by a high-speed mixer for a required time. While kneading and granulating, a neutralizing agent for suppressing alkalinity (1.0% based on the raw material) was added, and the mixture was granulated to a predetermined particle size and then discharged from the mixer. As a result, test results as shown in the following test report 2 could be obtained.

Test report 2 Sep. 20, 1993, Material No. 33 Tester: Kumamoto Prefectural Industrial Technology Center Analysis item: pH value, disintegration test Test method: pH: JIS X 0102, disintegration test: as noted Client: UK Environmental Service Co., Ltd. (Note: Nippon Chemi-Tac Co., Ltd. provided the test sample and the required expenses) Test sample: granular solid Result pH value 7.1 Disintegration test Material Disintegration rate 24 hours immersion After 3.4% After shaking for 6 hours 35.2% Remarks: Disintegration test Washed and dried material is sieved, shaken continuously with a 10-mesh sieve top shaker (200 rpm), and shaken continuously for 10 hours.
The weight on the mesh screen was measured to determine the disintegration rate. Remarks: The disintegration rate after standing for 24 hours in immersion is only 3.4% and 35.2% after shaking. Judging from the results of this test alone, it is inferred that the material has the strength as a landfill material even if the wear during loading on a truck or the like is considered. Similar results were obtained when other admixtures (products of three companies) were used.

[0019]

Example 2 Further, a cement-based solidifying agent and an admixture such as Geodol were added to the construction sludge and the oil-containing sludge at the following ratios.
Granulation was performed with a high-speed mixer. That is, a cement-based solidifying agent 1 is added to a sludge material obtained by mixing about 10% of oil-containing sludge with construction sludge.
0-20% (weight ratio of material) and admixture 2 such as geodol
% (Material weight ratio) was added and after curing for 7 days was kneaded and granulated at the required time high-speed mixer, in the 1.5% original material ratio
A neutralizing treatment was performed by mixing a wetting agent . The following is shown in the composition table.

As a result, a particle size distribution as shown in FIG. 1 corresponding to Tables 2 and 3 was obtained.

[0021] The sludge pellet is a granulated material that fits in the fine aggregate particle size distribution of the Japan Society of Civil Engineers, so the coarse particle ratio is close to the rough value of natural sand.

The following pH value of certificate 3 was obtained: Measurement certificate 3 January 25, 1994 Tester: Nippon Inspection Co., Ltd. Tokyo Physical and Chemical Laboratory Test method: According to the Notification of the Environment Agency Notification No. 13 Client: Nippon ChemiTAC Co., Ltd. : 8.0

A concrete casting test using 100% of the building sludge pellets was conducted. Concrete mixing conditions were as follows. W: water, C: cement, S: sludge pellet (granulated material),
A: Total aggregate amount, G: Coarse aggregate amount, W / C = 53.7%, S / A = 49%, W = 171.7 by weight ratio.
Kg, C = 320 Kg, G = 973.3 Kg, (coarse aggregate maximum dimension = 20 mm), slump = 8 cm, air volume = 4
%. As a result, the strength as shown in the following Test Report 3 was obtained.

[0024]

As described above, according to the present invention, cement-based solidifying agents, and construction sludge and solidifying agents penetrate into hydrated construction sludge to enhance their physical strength and chemical resistance. And a mixing method for adding a neutralizing agent for suppressing alkalinity, mixing these with a high-speed mixer, and granulating while mixing, or, on construction sludge, a cement-based solidifying agent, After adding an admixture that enhances physical strength and enhances chemical resistance, mix them using a high-speed mixer, granulate them to a maximum particle size of about 10 mm, and cure this granulated product for a certain period of time. , A predetermined amount to suppress alkalinity
The manufacturing method of processing by neutralization agent, inhibiting admixtures and alkali and solidifying agent of cementitious construction sludge neutralization
The agent was added and mixed to obtain a granulated solid. According to the present invention, the possibility of effective use of construction sludge, which has been mostly disposed of as industrial waste, is greatly increased, and the future disposal of shortage of final disposal sites and the accompanying increase in disposal costs are significant. effective. In addition, from the particle size distribution as shown in Table 1 corresponding to Table 2 and Table 3, the pH value of the measurement certificate 3 and the test report 3 data, this granulated material itself can be used as a fine aggregate as a civil engineering material. It is possible and could be used as a substitute for natural sand, which is expected to run short in the future. In particular, since the granulated product obtained by the present invention has a spherical shape, it is effective for utilization as fine aggregate such as fluidized concrete. It can also be used to produce industrial waste and other artificial raw materials with reduced alkalinity. The present invention is a solidified cement characterized in that it has a property of suppressing alkalinity and having a certain strength or more, so as a backfill material in places where the pH value of drainage standards is restricted by the Water Pollution Prevention Law etc. It can also be used as an artificial aggregate for concrete that does not cause an aggregate reaction.

[Brief description of the drawings]

1 is a graph showing the particle size distribution of the solidified product obtained by suppressing the alkaline present invention.

Continuation of front page (56) References JP-A-5-78664 (JP, A) JP-A-5-220498 (JP, A) JP-A-60-1006878 (JP, A) JP-A-4-349158 (JP) , A) JP-A-60-141785 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C02F 11/00-11/20 B09B 3/00 E02D 3/12 C09K 17/00 -17/52

Claims (2)

(57) [Claims] 1. A cement-based solidifying agent, an admixture which penetrates the construction sludge and the solidifying agent into water-containing construction sludge, enhances their physical strength and increases chemical resistance, and suppresses alkalinity. Add an appropriate amount of phosphoric acid-based agent as a wetting agent, mix them using a high-speed mixer, and granulate to a maximum particle size of about 10 mm while mixing. Method. 2. Addition of a cement-based solidifying agent and an admixture that penetrates the construction sludge and the solidifying agent to enhance the physical strength and enhance chemical resistance of the construction sludge containing water. Particle size up to 10mm while mixing using high speed mixer
After granulating to a degree and curing this granulated material for a certain period , phosphoric acid is the main component as a neutralizing agent to suppress alkalinity.
A method for producing a solidified product containing construction sludge as a main component, which is treated with a predetermined amount of a chemical .