JPS62260753A - Neutral consolidating agent and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an improvement in a neutral solidifying agent whose main ingredients are blast furnace water slag and expelled gypsum, and a method for producing the same. It is mainly used for solidification, mixing with cement, and as a substitute for cement.

(Conventional technology) For the improvement of soft ground and the solidification and treatment of sludge, blast furnace water slag has traditionally been dried and pulverized, followed by hydraulic slag to activate the hydraulic properties of the blast furnace water slag. A solidifying agent made by mixing a small amount of solidifying material is widely used, and assimilation treatment is performed by mixing a mixture of the solidifying agent and cement milk into soft soil or sludge and stirring it. The solidifying agent is produced by the reaction between the lime glass in the blast furnace water slag and the water-cum-lime in the mortar, etc., to produce silicate stone and aluminate lime, which are similar to the main compounds of Portland cement. It exhibits hardness and forms a dense hydrated mold to increase solidification strength.

However, the assimilation 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, sufficient assimilation effect cannot be obtained. Therefore, in actual use, a large amount of cement is required, leading to an increase 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, water content 120%, specific gravity 1.
When 459/cA of silty clay 1- is mixed with 120 hours of mixed milk of 1:1 of the solidification agent and cement milk, the indoor axial pressure strength after 30 bites is 2 to 3 kg.
/cri? degree (15 to 17 in the case of 300 kg mixed)
Kg/cyrf), and in order to increase the assimilation strength,
It requires a long curing period and large amounts of solidifying agent and cement milk.

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 by the action of an alkaline reaction accelerator such as cement or slaked lime, producing a so-called hardened ettringite material, which solidifies soft soil and the like.

However, in the case of assimilates manufactured using cement or slaked lime as stimulants, even if the amount of stimulants is increased (15-20%), the hydration reaction between alumina and gypsum is very slow and results in solidification. There are disadvantages in that it takes a long time, the solidified product exhibits strong alkalinity, and the compressive strength of the solidified product is extremely low.

In addition, in order to increase the hydration reaction rate between alumina and gypsum, potassium hydroxide (KOH) and sodium hydroxide (Na
A manufacturing method for a solidifying agent using a strong alkaline substance such as OH) as a stimulant is also being developed. However, even in this case, 15 to 20% by weight of a strong alkaline stimulant is required to promote the hydration reaction (the reaction rate will be saturated even if more is added).
As a result, the alkalinity of the solidified product becomes 10 to 11 in terms of pH, causing alkaline contamination of the soil and ground.
In the case of processing sludge, etc., there is a risk of secondary pollution due to the disposal of assimilated sludge. Furthermore, the assimilating agent produced by the above manufacturing method has a low rolling strength of the solidified product, and there is a risk of cracking due to alkali aggregate reaction, making it 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: (1) The solidified material is strongly alkaline, causing environmental pollution; (2) The solidified material is strongly alkaline and has low mechanical strength, making it unsuitable for use as a cement substitute. The solidified product has sufficient mechanical strength and can be used as a substitute for cement. The object of the present invention is to provide a method for dispensing assimilants that can also be used.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the inventors of the present invention have: ■ Added other substance components to the alkaline stimulant, thereby increasing the strength of the alkaline stimulant with a smaller amount of the alkaline stimulant. Obtaining the effect of accelerating the hydration reaction; ■ Neutralizing the solidified material by adding a substance component that exhibits a neutralizing effect as assimilation progresses; The idea was to increase the sensitivity to the stimulant and promote the hydration reaction by activating the alkaline stimulant itself; A number of tests were carried out using the mixing ratio of slag, waste gypsum, and Etsu gypsum as parameters, and various tests were conducted on the activation treatment of blast furnace water slag and waste gypsum using ozone.

The present invention was created based on the above-mentioned idea and various tests based on the idea, and the solidifying agent according to the first invention contains 1 to 4% magnesium and 1 to 5% magnesium. Calcium chloride, 1-5% by weight of cement and 0.1-5% by weight of cement
0.5% by weight of calcium hydroxide or both, 15% by weight or less of aluminum sulfate and 0.3% by weight or less of citric acid, 20-50% by weight or less of citric acid.
The basic 'R' composition consists of % by weight of flue gas desulfurization gypsum and the remainder being blast furnace water slag.

In addition, the second invention of the present application is to expose fine powder of blast furnace water slag and flue gas desulfurization gypsum in an ozone atmosphere for a certain period of time, and then to
-50% by weight of fine powder of ozonated flue gas desulfurization gypsum, 1-4% magnesium, 1-5% calcium chloride, 1-5% cement and 0.1% by weight ~
05% by weight of calcium hydroxide or both, up to 15% by weight of aluminum sulfate and 0.3 M
The basic structure of the invention is to mix one or both of citric acid of less than ffi% with the remaining part of the ozone-treated blast furnace slag fine powder.

(Function) In the solidifying agent according to the present invention, the hydration reaction between the alumina component in the water slag and gypsum is basically promoted by the alkaline stimulant, and the solidifying effect is achieved by producing hardened ettringite. is assumed to be played. At this time, by adding a small amount of magnesium and calcium chloride to an alkaline stimulant such as cement or calcium hydroxide, the stimulant is activated and its ability to promote the hydration reaction is greatly improved.As a result, The ettringite cured product is rapidly produced, the solidification time is shortened, and the solidification strength of the solidified product is significantly improved.

In addition, when the solidifying agent of the present invention is mixed with cement, etc., the lime-rich glass in the water slag reacts with the lime hydroxide in the cement, producing silicic acid similar to the main compound of Portland cement. Lime and aluminate lime are produced, and the resulting hydraulic action is superimposed on the solidification action.

Furthermore, it is assumed that the added aluminum sulfate and citric acid exert a neutralizing effect as solidification progresses, and neutralization of the solidified product is achieved.

In addition, by exposing the main components, the removed gypsum and blast furnace water slag, to an ozone atmosphere, the alumina components in the gypsum and water slag are activated, and together with the action of the stimulant, It is assumed that the production of ettringite is further promoted and a more dense hydrated aggregate 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, then drying it and pulverizing it (particle size 5
~307zm). 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-shaped chute from the top to the bottom inside the ozone generator, and the residence time of the fine powder in the ozone atmosphere is For 10-20 seconds, the power of the ozone generator light source is 2 KW x 10 units, and the processing capacity of slag fine powder is 10-15 Kg/min. As the blast furnace water slag, it is preferable to use molten blast furnace slag quenched with fresh water, and the exposure treatment in an ozone atmosphere is as follows: Retention for about 10 to 20 seconds is sufficient, and even if the ozone treatment is further strengthened, no significant change is observed in the increase in the a-loss strength of the solidified product.

Table 1 shows the chemical components of the blast furnace slag used in this example.

Table 1 Chemical composition of blast furnace water slag (wt%) On the other hand, flue gas desulfurization gypsum is produced by drying and finely pulverizing (particle size 5 to 20 μm) desulfurized gypsum from heavy oil-fired Akyo thermal power plants. It has chemical components as shown in Table 2. Furthermore, as in the case of blast furnace water slag, it has been proposed that the removed gypsum be exposed to an ozone atmosphere after drying and pulverization, and the ozone treatment conditions are the same as in the case of blast furnace water slag.

Table 2 Chemical components (wt%) of flue gas desulfurization gypsum Tables 3 and 4 show the mixing ratio of each component of the solidifying agent produced in this example.

Table 3 Components of solidifying agent (wt%) Table 4 Components of solidifying agent (% by weight) Cement and calcium hydroxide constitute the main irritants, and when cement is used alone, the amount of 1 to 5 w
t% addition is required. If the cement content is less than 1wt%, the hydration reaction between alumina and gypsum in the blast furnace water slag will not be promoted, and if the cement content is 5wt%, not only will the alkalinity of the assimilates increase, but the This is because the oxidation effect of the hydration reaction is 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. This is because the reaction rate does not improve much at the same time, and a mixing ratio of 0.1 to 0.2 Wt% is the optimum value. Incidentally, in this example, cement and calcium hydroxide are each used alone, but both can be used together, for example, cement I W t% and calcium hydroxide 0.1 W.
Of course, t% may also be used.

Magnesium and calcium chloride serve a supplementary function to the main stimulant, activating the main stimulant and significantly promoting the hydration reaction through a synergistic action with the main stimulant. In addition, in order to promote the hydration reaction, gold,
1 to 4 wt% of magnesium or magnesium oxide (
Optimum value is 1-2W t%), calcium chloride 1-5W
t% (optimal rg is 1 to 3 W t%), and if either falls below the minimum (direct), the promoting effect will decrease.Also, if the amount of magnesium and calcium chloride is 4
and 5 W, toto, the effect of promoting the hydration reaction is saturated. Therefore, the respective addition amounts are 4 and 5~V
t% or less.

If aluminum sulfate is added in an amount of 1.5 weight 1% or more, the expansion rate of the solidified product becomes too large and the solidified product tends to crack. As a result, the amount added was 15
It should be less than 0.08% to 1.2%.

If more than 0.3% by weight of Kuenshun is added, the solidification time of the assimilating agent will be significantly delayed, causing a serious problem in practical use. Therefore, when using a solidifying agent at high temperatures, it is desirable to add it in an amount of 0.3% by weight or less.

Depleted gypsum and blast furnace water slag (or blast furnace water slag treated with ozone) are the basic components of the solidifying agent, and the ratio of the two (blast furnace water slag/depleted gypsum) is approximately 1 to 4. The height is appropriate, preferably 1.2 to 2.0. Even if the amount of gypsum is insufficient and becomes less than 20 wt%, or even if the amount of gypsum exceeds sowt% and the blast furnace water slag becomes insufficient, the solidifying performance and assimilation strength of the solidifying agent will decrease.

Therefore, in this example, the amount of removed gypsum is 20 to 50%.
Wt%, and the remainder after removing the stimulant and activator is blast furnace water slag. It should be noted that the ratio between the amount of blast furnace water slag and the amount of gypsum includes a considerably larger value than the theoretical value,
The reactivity of the alumina component in the blast furnace water slag with removed gypsum (dihydrate gypsum) is related to the solubility of gypsum, so even if there is a considerable shortage of gypsum, it is not possible to obtain extremely good solidification characteristics than theoretically suggests. It has been confirmed that

FIG. 1A shows the solidification test results of the solidifying agent according to the first invention of the present application as described in Table 3 above, and the mixing ratio of the solidifying agent and water (solidifying agent/water) was 1°7. This is the first shift at the time. In the case of this solidifying agent, the compressive strength is 1soK in 7 days after mixing.
y/ffl, 270 Kg/cffl % in 14 days
It becomes 390 Kg/ffl in 28 days, and exhibits a solidification rate and solidification strength that are approximately close to those of Portland cement (190 Kg/cn in terms of compressive strength after 7 days when the cement/water mixing ratio is 17).

Furthermore, the alkalinity of the solidified product caused by the assimilating agent is P H
7.7 to 7.8, which is slightly alkaline and almost neutral, and the alkalinity is significantly lower than that of conventional cement-based hardeners whose main ingredient is blast furnace water slag.

Furthermore, when 1 m' of silty clay with a water content of 120% and a specific gravity of 1.45 Kg/ffl is mixed with 120 kg of molten milk of the solidifying agent according to the present invention, the temperature at atmospheric temperature (average 18°C) In natural solidification, the indoor-axial compressive strength after 30 days is 4 to 5 Kg/cyf, and the compressive strength of the solidified product is 4 to 5 Kg/cyf, compared to the conventional cement-based solidifying agent mainly made of blast furnace water slag. It is improved by 20-30% and the solidification time is also significantly shortened.

Table 5 below shows data when the solidifying agent according to the first invention of the present application was used at a landslide site (Constructed by Nippon Koei Co., Ltd., Uchiyama landslide site, January 30, 1986) )0 Table 5 On the other hand, B in FIG. 1 above shows the solidification test results of the solidifying agent produced according to the second invention of the present application, and the mixing ratio of the solidifying agent and water (solidifying agent/water) is: As in the case of the first invention, 1.7 is selected.

In the case of the assimilate produced according to the second invention, the compressive strength is 2ooKg/m in 7 days after mixing and 330Kg/cr in 14 days.
r.

It reached 540 kg/cm in 28 days, and has approximately the same solidification speed and compressive strength as Portland cement.

Furthermore, it has been found that the compressive strength is improved by approximately 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 slightly alkaline, which is approximately neutral at pH 73, and the alkalinity is significantly lower than that of the conventional cement-based hardening agent whose main ingredient is blast furnace water slag.

Furthermore, using the solidifying agent produced according to the present invention, the water content ratio is 12.
Silty clay 1 with 0%, specific gravity 1.45 h/crd
When the molten milk of the solidification agent is mixed with 120 to 7 on the door, during natural solidification due to atmospheric temperature (average 18°C),
After 30 days, the indoor-axial compressive strength is 6 to 7 Kg/cM, which improves the compressive strength of the solidified product by 30 to 40% compared to the conventional cement-based solidifying agent based on blast furnace water slag, and also reduces the solidification time. is also significantly shortened.

(Effect) The anabolic agent according to the present invention significantly enhances the effect of promoting the hydration reaction of the alkaline stimulant by adding magnesium oxide, etc., so that a rapid solidification effect can be achieved with a small amount of the alkaline stimulant. In addition, the added aluminum sulfate and citric acid have a neutralizing effect during the solidification process of the solidifying agent.As a result, even if the assimilating agent is used for soil improvement or sludge assimilation, So-called alkali contamination hardly occurs, and the time required for the solidification work is significantly shortened, thereby improving work efficiency.

In addition, the solidifying agent according to the present invention has a solidifying speed and compressive strength of the solidified product that are approximately the same as those of Portland cement, and can be used for construction and building materials as a cement substitute. There is also almost no risk of cracking of the structure due to so-called alkaline aggregate 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.

In addition, in the solidifying agent according to the second invention of the present application, the main components, blast furnace water slag and expelled gypsum, are exposed for a certain period of time in an ozone atmosphere, so that both of them are With a small amount of irritants, the degree of hydration, the core progresses rapidly, and a dense water deposit structure is formed. As a result, the assimilation rate and compressive strength of the solidified material are largely improved.

[Brief explanation of drawings]

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 first invention of the present application. B Characteristic curve of the solidifying agent according to the second invention of the present application. 1 other person

Claims (2)

[Claims] (1) 1-4% by weight of magnesium, 1-5% by weight of calcium chloride, 1-5% by weight of cement and 0.1% by weight
~0.5% by weight of either or both of calcium hydroxide, 1.5% by weight or less of aluminum sulfate, and 0.3% by weight of aluminum sulfate or less.
Either or both of citric acid in an amount of 20 to 20% by weight or less
A neutral solidifying agent consisting of 50% by weight flue gas desulfurization gypsum and the balance consisting of blast furnace water slag. (2) 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
% by weight of ozone-treated flue gas desulfurization gypsum fine powder, and 1
-4% by weight magnesium, 1-5% by weight calcium chloride, 1-5% by weight cement and 0.1-0.5% by weight
% by weight of either or both of calcium hydroxide and 1
．． A medium characterized by mixing either or both of 5% by weight or less of aluminum sulfate and 0.3% by weight or less of citric acid, and the balance equivalent to the fine powder of the blast furnace water slag subjected to the ozone treatment. Method for producing a solidifying agent.