JPH0339984B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing a solidifying agent mainly composed of blast furnace water slag and expelled gypsum, and is a method for improving soft ground, solidifying sludge, and as an admixture for cement and a substitute for cement. It is mainly used for etc. (Conventional technology) To improve soft ground and solidify sludge, blast furnace water slag has traditionally been dried and crushed, and a small amount of hydraulic inorganic material is mixed in to activate the hydraulic properties of blast furnace granulation. A solidification agent manufactured by the above-mentioned method is widely used, and the solidification treatment is performed by mixing a mixture of the solidification agent and cement milk into soft soil or sludge and stirring the mixture. The solidifying agent is produced by the reaction between lime glass in blast furnace water slag and hydroxide lime in mortar, etc., to produce lime silicate and lime aluminate, which are similar to the main compounds of Portland cement, and improve hydraulic properties. At the same time, it forms a dense hydrated structure and increases the solidification strength. However, the solidifying agent produced from the blast furnace water slag usually needs to be mixed with cement milk at a ratio of about 1:1, and if the mixing ratio of cement milk is reduced, a sufficient solidifying effect cannot be obtained. Therefore, in actual use, a large amount of cement is required, leading to a rise in ground improvement costs and sludge treatment costs. Furthermore, the solidifying agent requires a considerable curing period to complete solidifying, and has the disadvantage that the compressive strength of the solidified product is not sufficiently increased. For example, for 1 m ³ of silty clay with a water content of 120% and a specific gravity of 1.45 g/cm ³ ,
When 120 kg of mixed milk with a 1:1 ratio of solidification agent and cement milk is mixed, the indoor axial compressive strength after 30 days is about 2 to 3 kg/cm ² (15 to 17 kg/cm ² if 300 kg is mixed) In order to increase the solidification strength, a long curing period and a large amount of solidification agent and cement milk are required. On the other hand, it has been known that blast furnace water slag undergoes a hydration reaction with gypsum in the presence of an alkaline stimulant and has the effect of solidifying soft soil and the like. That is,
The alumina component in the blast furnace water slag undergoes a hydration reaction with gypsum due to the action of alkaline reaction accelerators such as cement and slaked lime, producing so-called hardened ettringite, which solidifies soft soil and the like. However, with solidifying agents manufactured using cement or slaked lime as stimulants, even if the amount of stimulant is increased (15 to 20% by weight), the hydration reaction between alumina and gypsum is extremely slow, and solidification takes a considerable amount of time. Moreover, there are disadvantages in that the solid material exhibits strong alkalinity and the compressive strength of the solidified product is extremely low. In addition, in order to increase the rate of hydration reaction between alumina and gypsum, a method for producing a solidifying agent is being developed that uses strong alkaline substances such as potassium hydroxide (KOH) and sodium hydroxide (NaOH) as stimulants.
However, even in this case, 15 to 20
% by weight of a strong alkaline stimulant is required (the reaction rate will be saturated even if more is added), and as a result, the alkalinity of the solidified product will be about 10 to 11 in terms of PH value, which will prevent alkaline contamination of soil and ground. In addition, in the case of processing sludge, etc., there is a risk of secondary pollution due to the disposal of solidified sludge. Furthermore, the solidifying agent manufactured by the above-mentioned method has a low compressive strength, and there is a risk of cracking due to the reaction with the alkali aggregate, making it completely impossible to use it in construction as a substitute for cement. (Problems to be Solved by the Invention) The present invention solves the above-mentioned problems with conventional solidifying agents mainly composed of blast furnace water slag, namely, the solidifying time is quite long and the compressive strength of the solidified product is relatively low. This is an attempt to solve problems such as the solidified material is strongly alkaline, causing environmental pollution, and the solidified material is strongly alkaline and has low mechanical strength, making it unsuitable for use as a cement substitute. It is an object of the present invention to provide a method for producing a solidifying agent that has a fast solidifying rate, is weakly alkaline, does not cause environmental pollution, and has sufficient mechanical strength as a solidified product, and can be used as a substitute for cement. This is the purpose. (Means for Solving the Problems) In order to solve the above-mentioned problems, the inventors of the present application have developed a method for achieving strong hydration with a smaller amount of alkaline stimulants by adding other substance components to the alkaline stimulants. The idea was to increase the sensitivity to stimulants and promote the hydration reaction by obtaining a reaction promoting effect and activating the main components, blast furnace water slag and expelled gypsum itself. Regarding combinations of stimulants and additives, we conducted numerous solidification tests using their mixing ratios and the mixing ratio of blast furnace water slag and removed gypsum as parameters, as well as the activation of blast furnace water slag and removed gypsum using ozone. Various tests were conducted regarding the treatment. The present invention was created based on the above idea and various tests based on the idea, and the present invention exposes fine powder of blast furnace water slag and flue gas desulfurization gypsum in an ozone atmosphere for a certain period of time, and then processes it for 20 days. ~50% by weight
fine powder of ozone-treated flue gas desulfurization gypsum, and 1
~4% by weight magnesium, 1-5% by weight calcium chloride, 1-5% by weight cement and
1. A method for producing a solidifying agent, which comprises mixing 0.1 to 0.5% by weight of either or both of calcium hydroxide and the remaining portion of fine powder of blast furnace slag treated with ozone. (Function) The solidifying agent produced according to the present invention basically has a solidifying effect by promoting the hydration reaction between the alumina component in the blast furnace water slag and gypsum by an alkaline stimulant to produce a hardened ettringite product. is assumed to be played. In addition, when used in combination with cement, etc., the high lime glass in the blast furnace water slag reacts with the hydroxide lime in the cement to produce lime silicate and lime aluminate, which are similar to the main compounds of cement. However, the hydraulic action caused by these is superimposed on the solidification action. By adding a small amount of magnesium and calcium chloride to an alkaline stimulant such as cement or calcium hydroxide, the stimulant is further activated, its ability to promote the hydration reaction is improved, and the formation of the hardened ettringite product is promoted. The solidification time is shortened and the mechanical strength of the solidified product is also improved. In addition, by exposing the main components, expelled gypsum and blast furnace water slag, to an ozone atmosphere, alumina components in the gypsum and water slag slag are activated, and together with the action of the stimulant, ettringite It is assumed that the formation of is further promoted and a more dense hydrated structure is formed, thereby achieving a significant improvement in the mechanical strength of the solidified product. (Example) Hereinafter, the present invention will be explained in detail based on an example of the present invention. Blast furnace slag is produced by rapidly cooling molten blast furnace slag discharged from a blast furnace with fresh water or seawater, drying it, and pulverizing it (particle size: 5 to 30 μm). The pulverized blast furnace water slag is subsequently introduced into an ozone generator, where it is exposed to an ozone atmosphere for a certain period of time. The ozone exposure treatment is carried out by dropping fine slag powder along a zigzag chute from top to bottom inside the ozone generator, and the residence time of the fine powder in the ozone atmosphere is 10 minutes. ~20 seconds, the power of the ozone generator light source is 2KW x 10 units, and the processing capacity of slag fine powder is 10-15Kg/min. It is preferable to use molten blast furnace slag quenched with fresh water as the blast furnace water slag, and for exposure treatment in an ozone atmosphere, as mentioned above, the power of the ozone generator light source is 2KW.
In the case of ×10 groups, retention for about 10 to 20 seconds is sufficient, and even if the ozone treatment is further strengthened, no significant change in the increase in mechanical strength of the solidified product is observed. Table 1 shows the chemical components of the blast furnace slag used in this example.

[Table] On the other hand, flue gas desulfurization gypsum is produced by drying and finely pulverizing (particle size 5 to 20μ
m) and has the chemical components as shown in Table 2. Further, as in the case of blast furnace water slag, the removed gypsum is subjected to a bleaching treatment in an ozone atmosphere after drying and pulverization, and the ozone treatment conditions are the same as in the case of the blast furnace water slag.

[Table] Tables 3 and 4 show the mixing ratio of each component of the solidifying agent produced in this example.

【table】

[Table] Cement and calcium hydroxide constitute the main stimulants, and when cement is used alone, it is necessary to add 1 to 5 Wt%. If the cement content is less than 1 Wt%, the hydration reaction between the alumina and gypsum in the blast furnace water slag will not be promoted, and the cement
If it exceeds 5 Wt%, not only will the alkalinity of the solidified product increase, but the effect of promoting the hydration reaction will be saturated, and a mixing ratio of 1 to 3 Wt% is most suitable. The same is true when using calcium hydroxide as the main stimulant; below 0.1 Wt%, the hydration reaction is too slow, and above 0.5 Wt%, the alkalinity of the solidified product increases and the reaction rate increases. This is because the improvement is not so great in this case, and a mixing ratio of 0.1 to 0.2 Wt% is the optimum value. Although cement and calcium hydroxide are used alone in this example, it is also possible to use both together, for example, 1Wt% of cement and 0.1Wt% of calcium hydroxide. Of course. Magnesium and calcium chloride serve a supplementary function to the main stimulant, activate the main stimulant, and significantly promote the hydration reaction by acting synergistically with the main stimulant. In addition, in order to promote the hydration reaction, it is necessary to add 1 to 4 Wt of magnesium.
% (optimal value is 1-2 Wt%), calcium chloride 1
~5Wt% (optimal value is 1 to 3Wt%) is required, respectively.
If either falls below its minimum value, the promoting effect decreases. Furthermore, when the amounts of magnesium and calcium chloride exceed 4 and 5 Wt%, respectively, the effect of promoting the hydration reaction is saturated. Therefore, the amounts added should be 4 and 5 Wt% or less, respectively. Ozone-treated degassed gypsum and ozone-treated blast furnace water slag are the basic components of the solidifying agent, but the ratio of the two (blast furnace water slag/degassed gypsum)
is approximately 1 to 4, but is appropriate, preferably 1.2 to 4.
2.0 is optimal. 20Wt% due to insufficient amount of gypsum
Even if the amount of gypsum exceeds 50 Wt% and the blast furnace water slag becomes insufficient, the solidifying performance and solidifying strength of the solidifying agent will decrease. Therefore, in this embodiment, the amount of removed gypsum is 20 to 50 Wt%, and the remainder after removing the stimulant and activator is blast furnace water slag. Although the ratio of the amount of blast furnace water slag to the amount of gypsum includes a value considerably larger than the theoretical value, the reactivity of the alumina component in the blast furnace water slag to removed gypsum (dihydrate gypsum) is due to the reactivity of gypsum. Because it is related to solubility, etc., even if there is a considerable shortage of gypsum compared to the theoretical value,
It has been confirmed that extremely good solidification properties can be obtained. FIG. 1 shows the solidification test results of the solidification agent produced according to the present invention described in Table 3 above,
Curve A relates to the solidifying agent according to the invention. In addition, curve B has the same chemical components,
These are the values when using blast furnace water slag and gypsum that have not been subjected to ozone treatment, and both values are when the mixing ratio of solidifying agent and water (solidifying agent/water) is 1.7. In the case of the solidifying agent produced according to the present invention, the compressive strength is 200 Kg/cm ² after 7 days and 330 Kg/cm ² after 14 days after mixing.
It has a solidification rate and compressive strength of 540Kg/cm ² per day, which is approximately the same as that of Portland cement.
Furthermore, it has been found that the compressive strength is improved by about 30% compared to the case where blast furnace water slag and gypsum are not exposed to an ozone atmosphere. The alkalinity of the solidified product by the solidifying agent is PH
8.5, it is weakly alkaline, almost neutral,
The alkalinity is significantly lower than that of conventional cement-based hardeners based on blast furnace water slag. Furthermore, 1 m ³ of silty clay with a water content of 120% and a specific gravity of 1.45 Kg/cm ² was prepared using the solidifying agent produced according to the present invention.
When 120 kg of molten milk of the solidification agent is mixed with
During natural solidification due to atmospheric temperature (average 18℃),
After 30 days, the indoor unconfined compressive strength is 6 to 7 Kg/ ^cm2 , which improves the compressive strength of the solidified product by 30 to 40% compared to the conventional cement-based solidifying agent that mainly uses blast furnace water slag, and also reduces the solidifying time. is also significantly shortened. (Effects) The solidifying agent according to the present invention is made by exposing the main components, blast furnace water slag and expelled gypsum, in an ozone atmosphere for a certain period of time, so that both are activated and less irritants are used. As the hydration reaction progresses rapidly, a dense hydrated structure is formed. the result,
The solidification speed and compressive strength of the solidified product are greatly improved. Further, since the solidifying agent according to the present invention significantly enhances the effect of promoting the hydration reaction of the alkaline stimulant by adding magnesium or the like, a rapid solidifying effect can be achieved even with a small amount of the alkaline stimulant. Therefore, even if soil improvement treatment or sludge solidification treatment is performed using the solidification agent, so-called alkali pollution will hardly occur, and the time required for solidification work will be significantly shortened, making it easier to work. Efficiency can be improved. Furthermore, the solidifying agent according to the present invention has a solidification speed and compressive strength of the solidified product that are approximately the same as those of Portland cement, and can be used for building materials as a cement substitute. There is also almost no possibility that cracks or the like will occur in the structure due to the reaction. Furthermore, the present invention aims to effectively utilize blast furnace water slag and removed gypsum, and has superior effects in terms of resource saving and low cost compared to conventional cement or cement-based solidifying agents. As mentioned above, the present invention has high practical utility.

[Brief explanation of the drawing]

FIG. 1 shows the curing and strength properties of the solidifying agent of the present invention. A...Characteristic curve of the solidifying agent according to the present invention. B...
Characteristic curve of a solidifying agent using blast furnace water slag and gypsum that have the same chemical components as those of the present invention but have not been subjected to ozone bleaching treatment.

Claims (1)

[Claims] 1. The fine powder of blast furnace water slag and the fine powder of flue gas desulfurization gypsum are exposed in an ozone atmosphere for a certain period of time, and then
20-50% by weight of fine powder of ozonated flue gas desulfurization gypsum, 1-4% by weight of magnesium, and 1-4% by weight of magnesium.
5% by weight of calcium chloride, 1 to 5% by weight of cement and 0.1 to 0.5% by weight of calcium hydroxide, or both, and the balance of fine powder of blast furnace slag that has been subjected to ozone treatment is mixed. A method for producing a solidifying agent, characterized by: