JPS5911390A - Increase in strength of odorous, hydrous soft earth accompanied by deodorization - Google Patents

Abstract

PURPOSE:To economically and efficiently deodorize hydrous soft earth and to increase its strength at the same time, by adding gypsum dihydrate, fine blast furnace slag, portland cement and a water-soluble ferrous salt in specified order and proportion to the hydrous soft earth. CONSTITUTION:A method comprising adding and mixing additives A, B and C hereinafter described with odorous, hydrous soft earth, wherein the additives A and C are added separately or together before addition of the additive B, and a wt. ratio of A/B is selected to be 75/25-55/45. The additive A is a mixture consisting of 5-45wt% gypsum dihydrate and 95-55wt% fine blast furnace slag of particle size of 100-1mum. The additive B is portland cement. The additive C is a water-soluble ferrous salt. Said additives A and B are most pref. added in a ratio of 70/30-60/40, wherein the additive A is pref. a mixture consisting of 15-35wt% gypsum dihydrate and 85-65wt% fine blast furnace slag.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for economically and efficiently deodorizing water-containing soft soil having a foul odor and increasing its strength.

Water-containing soft soils include marine soils that are deposited in closed sea areas, open sea areas, low-tide rivers, etc., freshwater soils that are deposited in rivers, lakes, reservoirs, purification ponds, water purification plants, etc., earth drill method, and bed piles. It is classified as civil engineering work-related waste emitted during construction methods, etc. Generally, these soft soils containing water are rarely odorless, and in many cases, they emit a unique foul odor. This bad odor makes the living environment in the vicinity extremely unpleasant. In addition, this soft soil containing water is difficult to handle, and in order to use it as a construction site or to transport it for other uses, it must be treated to increase its strength.

Conventionally, with regard to the treatment of hydrated soft soil, it has been known to independently perform strength increase and deodorization, but there is no known method that can perform both at once.

As a treatment method for the sole purpose of deodorizing water-containing soft soil, a method of adding slaked lime or quicklime is known. In this case, the purpose is achieved by increasing the pH value of water-containing soft soil that has a bad odor, converting hydrogen sulfide and mercaptans, which cause the bad odor, into calcium salts, which is not practical. In other words, according to this method, hydrogen sulfide and mercaptans will undergo a deodorizing reaction (
Calcium salt production reaction) is insufficient. In other words,
Unless the p11 value of the treated soil is maintained at 10 or more so that calcium salts generated by the deodorizing reaction can stably exist, hydrogen sulfide and mercaptans, which are bad smells, will be generated again. Since soft soil has a large pH buffering effect, in order to obtain a good deodorizing effect using this method, it is necessary to add a large amount of slaked lime or quicklime that exceeds this large pH buffering effect. As described above, it is impractical to use a large amount of lime such as slaked lime or quicklime because it impairs economic efficiency.Furthermore, when this is subjected to the strength increasing treatment according to the present invention, the gel strength of the target soil increases by 3-3. Secondly, this viscosity becomes very high, resulting in a major drawback in that it makes the workability of strength increasing treatment extremely difficult. Moreover, when slaked lime or quicklime is used, there is a drawback in that it is a dangerous substance and is subject to various restrictions in its handling, storage, and preservation. In addition, as another method, a method of adding a water-soluble trivalent iron salt such as ferric sulfate or ferric chloride has been proposed, but in this case as well, the results are not satisfactory for the following reasons. not give.

(a) Water-soluble trivalent iron salts are easily hydrolyzed to become insoluble hydroxides. When handling water-soluble trivalent iron salts as stable aqueous solutions, the pH value must be maintained below 2.5; if the pH value exceeds 3, most of the salt will precipitate as hydroxide. Resulting in.

Fe"+3820=Fe(OH)R↓+3H+ (1) The reaction between the precipitated hydroxide and the malodorous components hydrogen sulfide and mercaptan is a heterogeneous reaction, so the reaction does not proceed smoothly.

(b) In order for hydrogen sulfide, which is the main component of bad odor, to react with iron to produce iron sulfide, the pH value of the solution must be 4.5 to 8.
．． It needs to be 5. Therefore, it is difficult to obtain satisfactory results by adding water-soluble 34-valent iron salt alone.1゜(c) In order to harmonize the conditions in (a) and (b), water-soluble trivalent iron salt is added. It has been proposed to use it in combination with quicklime or slaked lime, but since hydrolysis of the iron salt occurs, it is not satisfactory unless a large excess of iron salt is added relative to the stoichiometry of hydrogen sulfide, which is the cause of the odor. You won't get the results you want.

(d) When iron salt is reacted with the iron salt in the form of an insoluble hydroxide, the deodorizing reaction becomes a heterogeneous reaction, so the amount supplied is even larger than under the conditions in (c). Satisfactory results cannot be obtained unless more iron is supplied and the processing time is lengthened.

(e) When the soil treated in section (b) is further subjected to the strength increasing treatment of the present invention, the pH value of the target soil has decreased, so the strength increasing effect is significantly inhibited.

In addition, as a deodorizing treatment, it is also possible to consider a method in which hydrogen sulfide, which is a malodorous substance, is physically adsorbed onto Barley 1 or the like. However, with this method, the adsorption equilibrium of hydrogen sulfide, etc. due to physical adsorption is greatly affected by temperature, and a large amount of adsorbent must be used to completely adsorb hydrogen sulfide, etc. without causing a bad odor. There are also problems such as the fact that it is necessary to remove the odor, and that it does not have the effect of sterilizing or preventing the proliferation of bacteria that cause the odor, so it must be treated as a secondary treatment. In order to chemically and efficiently deodorize water-containing soft soil that has a bad odor, the following problems (a) to (e) must be solved.

(a) The deodorizing agent to be reacted with the malodorous substance is water-soluble, and the product of the deodorizing reaction is an insoluble substance that is physically and chemically stable under the conditions of the strength increasing treatment of the target soil and in the treated soil. It is necessary to select the one that will.

(b) The conditions for deodorizing treatment include conditions that allow the water-soluble deodorizing agent to selectively and completely react with malodorous substances in preference to competitive reactions with impurities, and the deodorizing agent as a reaction raw material. Conditions must be met so that the substance does not change into an insoluble substance before it reacts with the substance causing the odor. For this purpose, it is necessary to specify the concentration of the deodorizing agent, the pH value and oxidation of the reaction atmosphere, the reduction potential and temperature, the method of addition to the target soil, and other various conditions.

(C) Even if the deodorizing agent is added in excess to the target soil, it will not remain and cause any harm to the strength increasing agent, and furthermore, it will not be physically affected by the presence of debris or other conditions. It is necessary to select a deodorizer and treatment conditions that will transform it into a chemically stable insoluble substance.

In general, strength increasing agents containing cement have a temporary deodorizing effect on soft, water-containing soil that generates bad odors due to the calcium hydroxide (slaked lime) that is produced as a by-product from the hydration reaction of the cement. As mentioned above, its deodorizing effect is greatly affected by the pH value condition of the water-containing soft soil, and is not stable over a long period of time.Furthermore, its strength-increasing effect is not very large. This is because the foul-smelling, hydrated soft soil contains a considerable amount of organic matter, and the hydraulic action (hydration reaction) of cement is significantly influenced by this organic matter. Therefore, in the case of a strength increasing agent containing cement, certain measures are required in order to apply it to soft, water-containing soil that gives off a bad odor.

In view of the above-mentioned circumstances regarding strength increase and deodorization of hydrated soft soil, the present inventors have conducted extensive research to develop a method that can achieve both strength increase and deodorization at once, and as a result, have completed the present invention. It has arrived.

The present invention consists of adding and mixing additives A, B, and C shown below to water-containing soft soil having a bad odor; Additive A
and C are added separately or simultaneously before addition of additive B; and the weight ratio A/B of additives A and B is 75/
25 to 55/45; This is a method for increasing strength accompanied by deodorization of water-containing soft soil having a bad odor.

Additive A: 5-45% by weight of dihydrate lime and particle size 100-100%
Mixture of 95-55% by weight of 1 μm fine blast furnace water slag Additive B: Boltland cement additive C: Water-soluble divalent iron salt Additive C (deodorizer) is a water-soluble divalent iron salt, Q - Although any salt of an inorganic acid or an organic acid can be used, considering the influence on additives A and B and practicality such as economical efficiency, it is preferable to use ferrous sulfate and ferrous chloride. Among these, ferrous sulfate is the most preferred because it is produced in large quantities as a by-product during titanium production and is inexpensive. At the titanium manufacturing factory,
In many cases, ferrous sulfate is disposed of as industrial waste, so its use can kill two birds with one stone from the perspective of waste treatment and utilization.

The additive C1 used in the present invention, that is, the water-soluble divalent iron salt, is
It acts effectively under the usage conditions of Additive A in the present invention, that is, under slightly acidic to slightly alkaline conditions, does not adversely affect the strength increasing effect of Additives A and B, and has a foul odor in water-containing soft soil. Significantly increases the deodorizing effect of That is,
Under the treatment conditions of the present invention, this water-soluble divalent iron salt reacts efficiently with hydrogen sulfide and mercaptans, which are the causative substances of bad odor in sludge, etc., and fixes them. The reaction in this case is expressed by the following formula.

HzS +Fe2″-→Fe5 (solid) + 2H+
(2)2 RS H+ Fe 2-(RS)2
Fe (solid) + 2H+ (3) This reaction occurs selectively even in the presence of carbon dioxide gas and is not hindered by carbon dioxide gas. Carbon dioxide gas is present in the gas generated from hydrous soft soil, which has a bad odor, in a larger amount than hydrogen sulfide, which is the substance that causes the bad odor. It has the advantage of later reacting with this carbon dioxide gas to form non-polluting ferrous carbonate (siburite). In addition, in the case of water-soluble divalent iron salts, their solubility is affected by their pH value in the range of acidic and neutral solutions (hydrolysis does not result in precipitation products of ferrous hydroxide). First, the deodorizing reaction described above is smoothly performed within a pH range of 4.5 to 8.5. As mentioned above, this kind of thing
This was not observed in the case of divalent iron salts, and is a remarkable effect of water-soluble divalent iron salts.

The amount of water-soluble divalent iron salt to be added to hydrated soft soil is controlled by the amount of hydrogen sulfide contained therein and cannot be unambiguously determined, but in general, the amount of water-soluble divalent iron salt added to the hydrated soft soil is It may be added in an amount equal to or more than the same mole per minute. In this case, the total hydrogen sulfide content includes undissociated components and dissociated components dissolved in water in the soft soil, as well as solid substances; It does not contain insoluble sulfides. The total hydrogen sulfide content is determined by steam-distilling soft soil containing water and analyzing the hydrogen sulfide distilled out. Furthermore, insoluble sulfides bound to metals can be quantified by adding concentrated sulfuric acid to the distillation residue used for total hydrogen sulfide analysis, steam distilling it again, and analyzing the generated hydrogen sulfide. In the present invention, as mentioned above, the water-soluble divalent iron salt added in excess reacts with coexisting carbon dioxide gas to form Sibray 1-, and also reacts with the cation exchange component of soft soil. captured and immobilized. Therefore, in the present invention, the water-soluble divalent iron salt added will interfere with the strength increasing reaction by additives A and B, as long as the excess amount is within the range where it is fixed by such a reaction. Never. The cation exchange capacity of the target soil differs depending on the type and amount ratio of clay minerals and the amount ratio of humus contained in the soil particles. Therefore, the cation exchange capacity varies greatly depending on the target soil.

In order to efficiently deodorize hydrated soft soil with a bad odor using Additive C (soluble divalent iron salt), the soluble divalent iron salt must be added to the target hydrated soft soil prior to Additive B. It is necessary to disperse and mix the To this end, prior to the addition of Additive B, a soluble divalent iron salt may be dispersed and mixed in the form of an aqueous solution into the hydrated soft soil, or it may be uniformly dispersed in Additive A in advance and added to the hydrated soft soil. A method of mixing is used. When Additive C is added to water-containing soft soil after Additive B is added and mixed, the water-soluble divalent iron salt, which is the raw material of Additive C, becomes insoluble hydroxide due to the alkaline component of Additive B. Therefore, a rapid deodorizing reaction cannot be performed. Therefore, such a method of using Additive C is not preferred.

Next, additives A and B used as strength enhancers of the present invention
will be explained in detail.

191 Additive A used in the present invention is: 5 to 45% dihydrite
and 95 to 55% by weight of fine blast furnace water slag with a particle size of 100 to 1 μm (approximately the same or smaller particle size than cement). In the present invention, dihydrite, which is one of the raw materials for additive A, can be used in the form of powder or granules without any particular restriction on its particle size. Various types of by-product dihydrite can be used in the same form as they were recovered without increasing added value. In addition, blast furnace water slag, which is another raw material for additive A of the present invention, is;
In other words, granulated slag (hereinafter referred to as blast furnace slag) is made by quenching slag with wood and crushing it into sand or granules of about 1 to 5 mm.
was further pulverized to a particle size of 100 to 1 μm. The composition varies depending on the components of the iron ore and the operating policy of the blast furnace, but it is approximately as follows.

510230-35%, AQ20313-111%, C
aO3B~45%.

FezO30,5~1-0%, Mg03~6%, SO
,5-1,0%, Mn0O05~1.5%, Tl0Z
O, 5 to 1.0% Since this fine blast furnace water slag is used as a reactant as described above, it is essential to have latent hydraulic properties capable of exhibiting hydraulic properties due to the stimulating action of alkali or sulfate. This latent hydraulic property can be obtained by rapidly cooling the blast furnace slag, avoiding its crystallization, and making it amorphous (glass-like) in which crystallization energy is stored internally. The crystalline material obtained by slowly cooling blast furnace slag is melilite (Gehlenite Ca2 A f125107
・It is a dense crystalline substance whose main constituent minerals are okermanite (Ca2MgSi207 solid solution) and calcium orthosilicate, and it is unsuitable because it has no latent hydraulic properties. Furthermore, 1
Using ~5mm coarse grained blast furnace water slag as a raw material for additive A is difficult because the surface area that contributes to the reaction is too small.
This is not preferred because its reactivity is significantly reduced. When using fine blast furnace water slag with a particle size of 100 to 1 μm, which is one of the essential requirements of the present invention, the generally used 1 to 5 mm
Compared to the case where coarse-grained blast furnace water slag is used, the strength of the resulting treated soil is increased by 3 to 5 times. Dihydrite and fine blast furnace water slag included in Additive A can be added to soft soil containing water independently before Additive B is added and mixed.
Mixing is also possible, but in this case, it is not practical because the number of operations increases and a burden is placed on uniform mixing. It is important to uniformly mix these raw materials in advance in order to increase their reactivity. Additive A is a mixture of dihydrate slag and blast furnace slag prepared in a predetermined ratio.
It is made by pulverizing or by uniformly mixing a specified powder or unpulverized dihydrite into pulverized blast furnace slag alone. By-product dihydrate from flue gas desulfurization equipment is
In the separation process, it passes through a centrifuge and is recovered in a state containing about 10% free water by weight, but by mixing it with the dried blast furnace water slag at a predetermined ratio, it does not dry out.
Additive A can also be obtained by directly mixing and pulverizing.

In the additive A used in the present invention, dihydrite (×)
5-45% by weight and fine blast furnace water slag (Y) 95-55% by weight
It is necessary to consist of This was discovered through comprehensive experiments including the addition ratio with Additive B. If the dihydrate content in Additive A is less than 5% by weight, the effect of inhibiting the harmful effects of humus on the hydration reaction of Portland cement will not be satisfied, and additives A and B and the soil will be In between work 1 to ringite (3
CaO・A Q203-3CaSO4・28-3302
This is not preferable because the amount of gypsum necessary for the production reaction of 0) is insufficient, and the effect on increasing the strength of the hydrous soft soil is reduced. On the other hand, when the dihydrate slag content in Additive A is 45% by weight or more, that is, when the fine blast furnace slag content is 55% or less, more gypsum is supplied than is necessary for the above-mentioned ettringite production reaction. This is not preferable because the effect of increasing the strength of the hydrated soft soil becomes small due to the fact that the fine blast furnace water slag is insufficient as a reactant.

Next, the Pol 1-land cement used as the additive B is one that complies with Japanese Industrial Standard JIS R5210, and one of these that complies with ordinary Portland cement is generally used. However, depending on the conditions of hydrous soft soil treatment, portland cements conforming to standards such as medium-temperature heat portland cement, early-early-strength portland cement, and ultra-early-strength cement may be used alone or in combination.

The weight ratio A/B of additives A and B used in the present invention to be added to the hydrated soft soil is maintained in the range of 75/25 to 55/45 in terms of the effect on increasing the strength of the hydrated soft soil. is important. Under conditions other than these, a comprehensive optimum balance ratio of components cannot be obtained, the effect of increasing the strength of hydrated soft soil is small, and the treated soil is not preferable.

That is, if the addition weight ratio A/B is larger than 75/25, the proportion of Portland cement 1- is too small, and the calcium hydroxide (slaked lime) produced as a by-product by the water utilization reaction (hydraulic reaction) is too small. The purpose cannot be achieved because the various reactions that increase the strength of soft soils containing water, such as fine blast furnace water slag, in which reactions are induced as gold, do not occur sufficiently. On the other hand, if the addition weight ratio A/B is smaller than 55/45 (if the addition ratio of additive B is too large), dihydrate slag and fine blast furnace water slag will be insufficient, and the purpose of improving hydrated soft soil will be insufficient. cannot be achieved. If there is a shortage of dihydrate gypsum, not only will it be impossible to prevent the harmful effects of humification on the water use reaction of Portland cement, but also there will be a shortage of gypsum, which is necessary as a raw material for the ettringite production reaction that contributes to increased strength. A problem arises. In addition, if there is a shortage of fine blast furnace water slag, there will be a shortage of raw materials necessary for the ettringite production reaction, which will reduce the effect on increasing the strength of hydrated soft soil, as well as the following (,) to (d). Problems such as this arise.

(a) During the strength increasing treatment, heat generation increases, causing problems such as internal distortions occurring in the treated soil. (b
) The treated soil contains a large amount of calcium hydroxide, which is a by-product due to the hydration reaction of Pol 1-land cement, making the treated soil highly alkaline. (
C) Treated soil becomes more easily eroded by sewage and seawater.

(d) The cost of strength enhancers is high.

The most preferable addition amount ratio A of additives A and B in the present invention
/B is 70/30 to 60/40, and the preferred blending ratio of additive A at this time is 15 to 35% by weight of dihydrite (X) and 85 to 65% of heavy bases of fine blast furnace water slag (V). It is.

In order to preferably carry out the present invention, it is necessary to add additives A, B and C to water-containing soft soil in the following order (a) to (c).

(a) Additives A and C are simultaneously added and mixed to the water-containing soft 21-, and then additive B is added and mixed.

(b) Additive A and B after adding Additive C to soft soil containing water
Add and mix sequentially.

(c) After adding Additive A to the water-containing soft soil, Additive C is added and mixed, and then Additive B is added and mixed.

In this way, the hydrogen sulfide that causes the odor in the pre-processing process before adding and mixing Additive B reacts with the water-soluble divalent iron salt according to the reaction formula (1) above, and the hydrogen sulfide ( In addition, due to the action of additive A, the water-containing soft soil is converted into soft soil that exhibits high reactivity to the subsequent additive B.

The workability of adding and mixing Additive A in the pre-processing to the soft soil with water is extremely good, and the subsequent addition and mixing of Additive B to the soft soil with Additive A is uniform. In addition, the workability is improved so that it can be carried out easily, and the soil base is effectively modified so that the reaction caused by the addition of the additive B can occur smoothly.

The dihydrite contained in additive A is C per 100g of water.
Since it has a suitable solubility of about 0.2 g in terms of aSO4, when it is added and mixed onto a water-containing soft material, it does not have any adverse effects on gel strength, etc. (a)
Adverse effects such as humus in the target soil that adversely affect the hydration reaction to Pau 1-Land Cement 1 are suppressed, and (b) the cation exchange reaction with soil particles reaches a favorable equilibrium state. Therefore,
When additive B is added in the post-treatment step, various reactions necessary to increase the strength of the hydrous soft soil effectively occur.

Next, as a post-treatment step, additive B is added and mixed to this hydrous soft soil with increased reactivity. When the addition of Additive B starts the hydration reaction of its material, Portland cement 1~, the pH value of the target soil temporarily increases due to calcium hydroxide produced as a by-product, and Reactions between dihydrite (X) and fine blast furnace water slag constituting agent A, and various reactions between each material of these additives A and B and fine soil components are induced,
The strength of hydrated soft soil is increased. In this case, as mentioned above, the hydrated soft soil to which Additive A has been added and mixed has been modified into a soil base that easily induces various reactions that increase its strength, and furthermore, workability has been improved. Subsequent addition and mixing of additive B is uniform.

Moreover, it is easy to perform and achieves its purpose efficiently.

The strength increasing reaction of the hydrated soft soil in the present invention is (
a) Ion exchange reaction of soil fine soil particles and humus (b) Ettringite production reaction (C) Pozzolanic reaction producing tobermolite mineral-like phase (3Ca0, 2SiO□, 3H□0) (d) Non-contamination by W reaction Examples include crystalline gel material production reaction (e) and others.

Furthermore, when this additive B is added to the target soil, calcium hydroxide (slaked lime) is produced as a by-product during the reaction process, so the pH value of the target soil inevitably becomes temporarily high.

Therefore, the bacteria involved in the generation of foul-smelling gases in the target soil are killed, and the generation of foul-smelling gases is stopped.

As described above, in the present invention, when deodorizing and increasing the strength of water-containing soft soil with a bad odor, Additive A and Additive C are added and mixed in the pre-treatment process, and the additives A and C are added and mixed in the post-treatment process. Add and mix additive B. If you want to increase the strength of target soil that has been deodorized with Additive C, if Additive B is added and mixed with the target soil after Additive B is added and mixed, the workability of the operation will deteriorate. Furthermore, even if a special construction machine is used, it is difficult to achieve the purpose as efficiently as the present invention. That is, when Additive B is added to hydrated soft soil that has been deodorized with Additive C, it has a significant adverse effect on the viscosity, gel strength, and pH value of the hydrated soft soil. Due to this, the workability of the operation treatment inevitably deteriorates, and it becomes difficult to uniformly mix the water-containing soft soil. Along with this, the subsequent addition and mixing of additive A has an adverse effect on uniform dispersion and its various reactions, making it difficult to increase the strength of the hydrated soft soil. The cause of the adverse effect on the viscosity, gel strength, and pH value of hydrous softening caused by adding Additive B first is Ca''- and O1+- generated by the hydration reaction of Pol 1-land cement. Ca2+ and OH-, which are the causes, can be improved by using the strength increasing agent of the present invention and by specifying the order of addition of additives A and B to the hydrous soft material. Moreover, its various chemical properties can be effectively utilized.

As mentioned above, the major features of the present invention are that (a) a soluble divalent iron salt (additive C) is used as a deodorizing agent, and (b) the strength increasing agent is a highly reactive fine blast furnace water slag, dihydrite, etc. Three materials: Kou and Portland cement C) Their strength enhancers 3
The materials are divided into Additive A consisting of fine blast furnace water slag and dihydrite, and Additive B consisting of Pol-H Land Cement 1.d) Additive C (deodorizing agent) and Additive A. B
To efficiently achieve deodorization and strength-increasing treatment on the water-containing soft soil having a bad odor by adding and mixing additive B to the water-containing soft soil having a bad odor before addition and mixing thereto.

When carrying out the present invention, both additives A and B can be added in the form of powder or slurry.

According to the present invention, as described above, unlike conventional methods, the reaction between additives A and B and each component of the soil occurs extremely efficiently, and the strength of the treated soil is maximized. These additives A are taken into consideration to obtain the required strength increase.

The amount of B used can be small, and the time required to reach the required strength can be shortened. Regarding the soil to be treated, generally,
Those containing a large amount of clay minerals such as allophane, hydrated halosite 1-, montmorillonite, etc. have high reactivity, while those containing a large amount of olinite, chloride 1-, chloride 1-, etc. have lower reactivity than the former.

In addition, the reactivity varies depending on the content of fine particles such as clay (soil texture), the content of organic components such as humus, and the pH value, and the initial water content ratio also affects the effect of water content on softening and increasing strength. receive. However, the amount of the strength increasing agent of the present invention used to achieve the purpose of normal required strength is 1
The total amount of additives A and B is about 50 to 150 kg per m3. If the hydrated soft soil is suitable for strength-increasing reactions, such as when it contains a large amount of highly reactive clay minerals or has a small amount of organic matter, the amount of strength-increasing agent used should be reduced per 1 m3 of hydrated soft soil. Usually 50
~100Kg.

The method of the present invention can be applied not only to soft soil with a moisture content of 50 to 200%, but also to soft soil with an extremely high moisture content of 500 to 1000%. The initial water content ratio of the soil to be treated affects the improvement effect of the treated soil, but when the present invention is applied to soft soil with a high water content ratio,
More than a certain amount of water is separated from the treated soil by breathing and released onto its surface.

According to the present invention, as described above, it is possible to efficiently deodorize and increase the strength of odor-containing soft soil, but in this case, the amount of Portland cement that is the material of additive B added Since the amount of alkaline is relatively small, the heat generated by the hydration reaction is significantly suppressed, and no distortion occurs in the treated soil.Furthermore, since the amount of residual alkali in the treated soil is small, There is no increase in alkalinity in the soil, and the treated soil is not eroded by sewage or seawater. In addition, in the case of the present invention, the total amount of additives used is small, the proportion of Portland cement in the strength increasing agent is small, and the proportion of inexpensive blast furnace water slag is large, so it is extremely economical. It is. Furthermore, all of the additive raw materials used in the present invention are extremely inexpensive, except for cement.
In many cases, it can be obtained as industrial waste, so the present invention is very superior not only economically but also from an ecological perspective.

Next, the present invention will be explained in more detail with reference to Examples and Reference Examples.

In addition, in the examples described later, as additive A;
μm, water content 9%, composition: CaO31.2%, 5O3
44.1%) and commercially available fine blast furnace water slag (Y) (specific surface area 3600-4000 cm2/g, i.e., average particle size approximately 4 pm, as measured by the Blaine method, composition: 5i0232-35%, A
Q20315-16%, Ca041-44%, Mg04
~6%, Fe20B 0.5~1.2%, 5O08~1
．． (0%, which was glassy with almost no crystalline material when observed under a polarizing microscope) was used. In addition, as additive B; ordinary cement in Pol 1 to land cement (specific surface area 3 as measured by Blaine method)
300 cm2/g) was used. In addition, as the raw material water-containing soft soil; in the examples, sedimentary soft soil from Katagawa, Koto-ku, Tokyo was used.

This product has a water content of 348.4% and a particle size composition of 0 to 5 μm.
46%, 5-20 μm, 49%, 20 μm or more, and 25%, showing an average particle size of 5.2 μm. Moreover, this material has a density of 1.15 g/cm3 at a water content of 348%. pH
It shows a value of 8.0, a loss on ignition of 23.7%, an organic matter content of 21.2% by weight according to the dichromic acid test method, and a concentration of hydrogen sulfide in the generated gas of 1800 to 2000 ppm.
The total hydrogen sulfide content measured by iodometric titration of the steam distillate was 430 B (12.6 mmol) per Ikg of the sample. In addition, concentrated sulfuric acid was added to the distillation residue after analyzing the total hydrogen sulfide content, steam distilled again, and the insoluble sulfide bound to the metal was similarly analyzed and quantified.
6 mg (70.2 mmol). Also, reference example 1
~4-27=-5μm 42%, 5-1.0μm 1.9%, 1.0
-20 μm 25% and a density of 1.21 g/cm 3 at a water content of 260%, Osaka Nanko dredging bottom mud was used.

Example: For soft raw material with bad odor ±1 m3, divalent F in IQ
Additive C3Q consisting of a ferrous sulfate solution containing 15.6 g (0.28 mol) (equivalent to 4 kg of ferrous sulfate), 78 kg of additive A (X/'/ = 33/67) and 852 kg of additive They were added and mixed in the order of addition shown in Table 1. The mixture was thoroughly mixed using a mixer at each step. Next, this mixed sample was prepared with an inner diameter of 50 mm and a height of 10 mm.
It was poured into a 0mm cylindrical mold, kept at 20±1℃ in a thermostatic curing chamber for the required period of time, and then removed from the mold.
The pH was measured by the dissolution test specified in No. 3. The results are shown in Table 1. Note that C-A shown in the table indicates that Additive C and Additive A were added at the same time.

28- Reference Example 1 Additive A (X/Y = 3
0/70) was added and mixed uniformly with a mixer, and then 823.5 kg of additive was added and thoroughly mixed with a mixer.

Next, this mixed sample was treated in the same manner as in the example, and the uniaxial compressive strength was measured. In addition, in order to clarify the influence of the particle size of blast furnace water slag on the strength, a comparative test was conducted under the same conditions except that coarse-grained blast furnace water slag (V') was used. The results are shown in FIG. The particle size distributions of the blast furnace water slags Y and v' used are shown in Table 2.

In addition, the horizontal axis of Fig. 1 shows the number of days after treatment (wood age), and the vertical axis shows the uniaxial compressive strength of the treated soil (kgf/Cm2), and curve 1 in the figure is the reference side result of the present invention, the curve 2 shows the comparative test results.

Table 2 Reference Example 2 Same as Reference Example 1 except that 40.3 kg of Additive A was used for 1 m3 of soft raw material, the X/Y weight ratio was changed from 4/96 to 50150, and 26.9 kg of Additive B was used. The test was conducted as follows. The results on the 14th day of age are shown in Figure 2.

The horizontal axis of FIG. 2 shows the weight percentage of the wax contained in Additive A, and the vertical axis shows the axial compressive strength (kgf/cm2) of the treated soil.

The total amount of Additives A and 13 added to 1 m3 of raw material soft soil was 67.2 kg, and the test was conducted under the operating conditions of Reference Example 1 while varying the weight ratio of Additives A and B. The results on the 14th and 28th days of wood age are shown in Figure 3. The horizontal axis in Figure 3 is the weight percentage of additive B to the total amount of additives A and B added.
The vertical axis shows the uniaxial compressive strength (kgf/cm") of the treated soil. Curves 1 and 2 in the figure show the results for the treated soil 14 and 28 days after treatment (wood age). There is.

Reference Example 4 Figure 3 shows a comparison of test results when the order of addition of Additives A and B was reversed for the same sample hydrated soft soil as in Reference Example 1.

Table 3

[Brief explanation of the drawing]

Figures 1 to 3 are graphs showing the treatment results for hydrated soft soil, where Figure 1 shows the type of blast furnace water slag in Additive A, Figure 2 shows the stone wax content in Additive A, and Figure 3 shows the results of treatment of soft soil containing water. shows the influence of the proportions of additives A and B on the strength increase of treated soil. Patent applicant Toshiaki Ikeura, patent attorney representing Chiyoda Corporation

Claims (2)

[Claims] (1) For water-containing soft soil with bad odor; Additive A shown below,
Additives A and C are added separately or simultaneously before addition of Additive B; and the weight ratio A/B of Additives A and B is 75. /25
55/45. Additive A: Dihydrite 5-45% by weight and particle size 100-1
Mixture additive B of 95-55% by weight of micron fine blast furnace water slag
: Bol 1-Landcemen I~ Additive C: Water-soluble divalent iron salt (2) Additive A is 15 to 35% by weight of dihydrite and has a particle size of 1
00-1 μm fine blast furnace water slag 85-65% by weight, and the weight ratio A/B of additive A and additive B is in the range of 70/30 to 60/40. Method of Section 1.