JP2001163660A - Hardenable composition and hardened body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hardenable composition and a hardened body which is excellent in acid resistance and workability and allows the utilization of waste slag. SOLUTION: This hardenable composition and hardened body comprise molten slag powder (A) of 10-85 wt.% in which the molar ratio of CaO/SiO2 is 0.10-1.20, water glass (B) of 5-40 wt.% in terms of the solid content and alumina cement (C) of 5-70 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable composition capable of utilizing molten slag such as sewage sludge and municipal waste and having excellent acid resistance and workability, and a cured product thereof.

[0002]

2. Description of the Related Art Sewage sludge, incineration ash, fly ash, etc. of general garbage and the like contain a large amount of heavy metals, and therefore cannot be directly discarded in consideration of environmental pollution. Therefore, some municipalities fix heavy metals by converting sewage sludge and municipal waste into slag and use it for roadbed materials and landfills. In addition, for incinerated ash containing heavy metals, a method of fixing heavy metals with a chelating resin so as not to be re-eluted, then solidifying with cement and disposing of them is common. A method of using the incinerated ash as a cement raw material has also been considered.

However, in the method of fixing heavy metals with a chelate resin, since the chelate resin itself is extremely expensive, if a large amount of incinerated ash is solidified, the processing cost is enormous and uneconomical. Also, the method of using incinerated ash as a cement raw material is limited in the field of application in that the cement becomes expensive and the incinerated ash contains chlorine. Therefore, neither could be a complete recycling method.

[0004] On the other hand, blast furnace slag has already been reused as aggregate and roadbed material, and has been used as a raw material for mortar, concrete admixture and mixed cement. The purpose of using the blast furnace slag is to impart chemical resistance, that is, chemical resistance, sulfate resistance, and seawater resistance to the cured product. For Portland cement, C ₃ S, C ₂
The hydration of S produces a large amount of Ca (OH) ₂ and CSH gel. Ca (O 2) generated by adding blast furnace slag
H) ₂ immediately reacts with the blast furnace slag to form a CSH gel to increase the amount of CSH gel produced, thus improving the watertightness of the cured product. As a result, chemical resistance is exhibited.

However, the CSH gel produced here is not sufficiently resistant to acid, and reacts with sulfuric acid in a sulfuric acid atmosphere such as a sewage facility to produce gypsum. As a result, the cured product containing the same sometimes caused dissolution, expansion and destruction.

Water glass has been used to impart acid resistance to a cured product. This is because water glass produces silica gel having excellent acid resistance due to sodium silicofluoride, condensed aluminum phosphate and the like.

However, the silica gel produced here is inferior in water resistance and shrinks due to dehydration. Further, since unreacted water glass and soluble metal salts dissolve in water, the cured product becomes porous and has poor permeation resistance. It had the disadvantage of being bad. In order to improve such disadvantages, CaO / SiO
An acid-resistant cement composition containing a molten slag powder having a molar ratio of ₂ to 0.1 to 1.2, water glass, and aggregate has been devised (JP-A-10-218644). Although this is excellent in acid resistance and can use waste molten slag as a raw material, its dimensional stability and workability are not always satisfactory. For example, when an acid-resistant plaster mortar is produced using water glass and amorphous melted slag, the mortar has a high viscosity but has a high fluidity, so that it may flow down when applied to a wall surface or a ceiling. In addition, even if it can be applied thinly, remarkable cracking may occur after curing.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an acid-resistant curable composition and a cured product which do not have the above-mentioned disadvantages and can utilize waste molten slag.

[0009]

Means for Solving the Problems In view of such circumstances, the present inventors have conducted intensive studies, and as a result, the molar ratio of CaO / SiO ₂ including waste molten slag was 0.1 to 1.2. The present inventors have found that a composition containing a certain molten slag powder, water glass and alumina cement at a fixed ratio can provide a cured product having good workability and excellent acid resistance, and completed the present invention.

That is, the present invention relates to (A) CaO / Si
Molten slag powder 1 having a molar ratio of O ₂ of 0.10 to 1.20
The present invention provides a curable composition containing 0 to 85% by weight, (B) 5 to 40% by weight of water glass in solid content, and (C) 5 to 70% by weight of alumina cement.

The present invention also provides a cured product obtained by mixing the curable composition with water and curing.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The molten slag powder of the component (A) used in the present invention has a CaO / SiO ₂ molar ratio of 0.10.
Slag obtained by melting one or more raw materials such as sewage sludge, incinerated waste such as municipal garbage, clay, limestone, etc. at a high temperature, and quenching to obtain slag. It was done. Of these, waste melting slag such as sewage sludge melting slag and municipal waste melting slag is preferable in terms of economic efficiency and waste recycling. (A) Component C
The molar ratio of aO / SiO ₂ is from 0.10 to 1.20, and particularly preferably from 0.10 to 0.60. When the molar ratio is less than 0.10, the reactivity of the composition is low,
A durable cured product exhibiting sufficient initial strength cannot be obtained. On the other hand, when the molar ratio exceeds 1.20, calcium hydroxide remains in the cured product, which is reduced to 2% in the presence of sulfuric acid.
Since water gypsum is produced and causes expansion failure, the acid resistance of the cured product becomes insufficient.

The fineness of the component (A) is preferably from 2000 to 150 in terms of specific surface area from the viewpoint of developing strength of the cured product.
00 cm ² / g, more preferably 3000-15000 cm ²
/ G, particularly preferably 4000-15000 cm ² / g. Although those having a specific surface area of more than 15000 cm ² / g can be suitably used in the present invention, the upper limit is set to 15000 cm ² / g because the cost is not high and the pulverization is not economical. On the other hand, if it is less than 2000 cm ² / g, the hydration activity is poor and the strength of the cured product may be insufficient.

The water glass (B) used in the present invention is not particularly limited, and a commercially available water glass can be used.
In addition to No. 1, No. 2 and No. 3 specified by the standard, it can be used for non-JIS standard products manufactured and sold by each water glass maker. Can be used in combination.

The amount of water glass used is 5 to 5 in the curable composition.
It is 40% by weight, preferably 10 to 30% by weight (as solid content). If the amount is less than 5% by weight, a cured product having sufficient acid resistance cannot be obtained, and if it exceeds 40% by weight, the viscosity becomes too large, and molding or working may be difficult.

The alumina cement (C) used in the present invention is not particularly limited, and a commercially available one can be used. Preferably, the one having a high CaO.Al ₂ O ₃ content is preferable. For example, Lafarge “Sekar 51B
TF "and" Alumina Cement No. 1 "manufactured by Denki Kagaku Kogyo KK are preferred. The content of (C) may be in the range of 5 to 70% by weight. If it exceeds 70% by weight, good acid resistance is not exhibited. In addition, particularly at room temperature curing, since the amount of shrinkage of the cured product of the present invention tends to increase, the content is preferably set to 5% by weight or more to reduce shrinkage.

The curable composition of the present invention may optionally contain one or more binders (D) selected from blast furnace slag, converter slag, dephosphorized slag, desilicated slag, and desulfurized slag. it can. Used in the present invention,
The binder (D) is not particularly limited, and a commercially available binder can be used, but one having a fineness of 4000 cm ² / g or more in specific surface area is preferable. The content of the binder may be in the range of 1 to 30% by weight, but is preferably in the range of 5 to 20% by weight. By using the molten slag (A) in combination with the binder (D), a cured product having good strength development at room temperature curing can be obtained. The early strength can be obtained by increasing the content of the binder (D), but at the same time, when the content exceeds 30% by weight, the acid resistance tends to decrease. Therefore, the molten slag powder (A) using the content of the binder (D)
By adjusting the molar ratio according to the CaO / SiO ₂ molar ratio, a cured product having good acid resistance can be obtained. The molar ratio of CaO / SiO ₂ of the mixture of the molten slag powder (A) and the binder (D) is 1.20 or less, preferably 0.80 or less, and more preferably 0.60 or less in a preferable range from the viewpoint of acid resistance. is there. Further, the total of the alumina cement (C) and the binder (D) is preferably 6 to 75% by weight.

Further, the curable composition of the present invention further comprises:
Alkali metal salts (E) can be added. Examples of the alkali metal salts (E) used in the present invention include sodium metasilicate, sodium orthosilicate, powdered sodium silicate No. 1, sodium hydroxide, potassium hydroxide, lithium hydroxide and the like. Soda and sodium hydroxide are preferred. These are-in water glass (B).
By cutting the Si-O-Si- chains with alkali, the viscosity is reduced and the workability when used as mortar and concrete is improved. In addition, the addition of alkali stimulates molten slag to promote hardening. There is work.
Each of the alkali metal salts is used alone,
More than one type can be used in combination. These alkali metal salts are preferably added in an amount of 1 to 15% by weight, particularly preferably 1 to 7% by weight. When the alkali metal salt is added in excess of 15% by weight, the effect of increasing the strength can be obtained, but the effect of lowering the viscosity is not increased, especially when an alkali having a high alkalinity is added excessively.
Unevenness may occur on the surface of the cured product, which is not preferable.

When both the binder (D) and the alkali metal salt (E) are added to the curable composition of the present invention,
The sum of the components (C), (D) and (E) is 11 in the composition.
It is preferable to set it to 75% by weight.

The curable composition of the present invention further comprises an aggregate (F)
Can be contained. The mixing ratio of the aggregate can be 30 to 300% by weight based on the curable composition (not including the aggregate). As the aggregate, silicate fine aggregate or coarse aggregate is preferable. As fine aggregate, silica sand, silica powder and river sand, sea sand, and crushed sand having the same particle size and particle size as these are preferable. . The mixing ratio of the fine aggregate is as described above, but the mixing ratio of the coarse aggregate is 50 to 300% by weight.
It is preferable that The mixing ratio of the aggregate is 300
If the content is more than 10% by weight, acid resistance of the cured product can be obtained, but it is not preferable because strength is reduced and workability is deteriorated. On the other hand, if the blending ratio of the aggregate is less than 30% by weight, there is little significance in blending the aggregate.

The curable composition of the present invention can be made into plaster mortar, grout material, backfill material, and acid-resistant concrete by adding an appropriate amount of water and mixing. In addition, 8
No. silica sand and / or silica powder and specific surface area 8000 to 12000
If melted slag powder of cm ² / g is blended and an appropriate amount of water is added, it can be used as a ground injection material.

When the curable composition of the present invention is used as a plaster mortar, a grout material, a backfill material, etc., the method of application includes troweling, spraying, pumping, pouring and the like. The curing method is usually performed at the environmental temperature of the construction site except during the cold season. During the cold season, heating and curing may be applied after construction to avoid frost damage. When used as acid-resistant concrete, there are pumping and pouring depending on the construction volume. The curing method is usually performed at the environmental temperature of the construction site, and may be heated in a cold season.

[0023]

The curable composition of the present invention can be used as a cured product which can utilize waste molten slag and is excellent in acid resistance and workability.

[0024]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Examples 1-4, Comparative Example 1 Sewage sludge incineration molten slag [Ca
O / SiO ₂ molar ratio: 0.46, specific surface area: 5000 cm ²
/ G], water glass No. 1, water glass 3
No., blast furnace slag powder [specific surface area: 8000 cm ² / g],
Sodium metasilicate powder was used as the alkali metal salt, and JIS standard sand (JIS R 5201 compliant product) was used as the aggregate. Water was added to this in consideration of the water content in the water glass, and the total water content was adjusted and kneaded. Thereafter, the mixture was poured into a 40 × 40 × 160 mm triple-column formwork, cured at 20 ° C. in humid air for 3 days, demolded, and cured in water at 20 ° C. for 4 days to obtain a cured product.

Examples 5 to 10 and Comparative Example 2 After kneading in the mixing ratio shown in Table 1 in the same manner as in Example 1,
After pouring into a 50 × 100 mm cylindrical form and curing for 1 day in a moist air at 20 ° C., it was demolded and cured in water at 20 ° C. for 2 days.

Examples 11 and 12 and Comparative Example 3 After kneading at the compounding ratio shown in Table 1 in the same manner as in Example 1,
After pouring into a 50 × 100 mm cylindrical formwork and curing for one day at 20 ° C. in moist air, it was cured in water until each age.

Examples 13 and 14, Comparative Example 4 In the same manner as in Example 1, kneaded at the mixing ratios shown in Tables 1 and 2, to obtain a cured product.

Examples 15-17 Molten municipal waste slag [CaO / SiO ₂ molar ratio: 0.6
7, specific surface area: 5000 cm ² / g], and kneaded at the compounding ratio shown in Table 3 in the same manner as in Example 1 except for the above to obtain a cured product.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

Test Example 1 A change in drying shrinkage was measured according to JIS A 1129. FIG. 1 shows the results of measuring the drying shrinkage of Examples 1 to 4 and Comparative Example 1. 14 days after the start of the drying test,
Example 1 in which alumina cement was added to Comparative Example 1
In Example 4, the drying shrinkage was reduced by about 70 to 80%.

Test Example 2 The cured products obtained in Examples 5 to 10, 15 to 17 and Comparative Example 2 were measured for compressive strength in accordance with JISA 1108. The sample was immersed in a 1% by weight sulfuric acid solution, and the acid resistance was evaluated based on the change in weight after 3 days. Table 4 shows the results.

[0035]

[Table 4]

<Test Method> (Compressive strength) Specimen size: 5 mm in diameter × 10 mm in height Curing method: Demolding 1 day after molding, then curing in water at 20 ° C. Test method: JIS A 1108 (exposure to sulfuric acid) Size: 5mm diameter x 10mm height column Curing method: Demolding 1 day after molding, curing in water at 20 ° C for 6 days Test method: Exposure to 1% sulfuric acid at 20 ° C, measure weight change after 3 days

In Examples 5 to 10, 16 and 17,
When cured at room temperature at 20 ° C., the strength was equal to or higher than that of the cured ordinary cement shown in Comparative Example 2. In the sulfuric acid resistance test, the ordinary cement shown in Comparative Example 2 was dissolved, but the cured products shown in Examples 5 to 10 and 15 to 17 were:
It showed excellent acid resistance with almost no change.

Test Example 3 The compressive strengths of the cured products obtained in Examples 11 and 12 and Comparative Example 3 were measured. The specimens subjected to the sulfuric acid resistance test were 2
After curing in a moist air at 0 ° C., sealing and curing were performed at 20 ° C. for 7 days, and then immersed in a 5% by weight sulfuric acid solution, and acid resistance was evaluated by weight change at each age.

FIG. 2 shows the results of the compression test of Examples 11, 12 and Comparative Example 3 at each material age, and FIG. 3 shows the results of the sulfuric acid resistance test. The hardened bodies of Examples 11 and 12 are particularly excellent in strength development at the initial stage as compared with the hardened ordinary cement shown in Comparative Example 3, and exceed 40 N / mm ² at one day of age. Shows the strength. In the sulfuric acid resistance test, the cured ordinary cement of Comparative Example 3 was dissolved in the acid in one day.
The cured product shown in No. 2 hardly changed even at the age of 28 days, and showed high acid resistance.

Test Example 4 Workability after kneading of Examples 13 and 14 and Comparative Example 4 and the presence or absence of cracks were observed. The workability was evaluated by applying a resin iron to the vertical surface of the concrete retaining wall,
The adhesion to a trowel and the thickness were evaluated. The presence or absence of cracks is determined by applying a 30 cm x 60 cm RH on a sidewalk board specified in JIS A 5304 of 30 x 30 x 6 cm to a thickness of 1 cm.
, And visually confirmed 7 days later.

Table 5 shows Examples 13, 14 and Comparative Example 4.
4 shows the evaluation results of the workability and cracking test. Comparative Example 4
On the other hand, in Examples 13 and 14, the sagging during plastering work was suppressed by the improvement in plasticity, and the adhesion to the iron was reduced due to the decrease in viscosity, so that the workability was improved. In addition, cracking was suppressed by the reduction of drying shrinkage by the addition of alumina cement.

[0042]

[Table 5]

<Test Method and Evaluation Method> Plastering workability: The vertical surface of the concrete retaining wall was painted using a resin iron to evaluate the workability. Adhesion to iron ○: Adhesion to iron Low: good workability △: Some adhesion to iron is recognized but applicability possible ×: Difficult to apply to base due to strong adhesion to iron Thickness ○: 2cm thick, no sag until next day △ 1: Thickness applied, no sagging until next day ×: Sagging due to plasticity of mortar, impossibility of thickening Cracking: Thickness on 30 × 30 × 6 cm sidewalk board specified in JIS A 5304 Apply 1cm, 20
Cured at 60 ° C. and 60% RH. After 7 days, the degree of cracking was visually observed. ○: Almost no cracking was observed. △: Fine cracking was slightly observed. ×: Clear cracking was observed on the entire surface.

[Brief description of the drawings]

FIG. 1 is a view showing the results of a drying shrinkage test of a cured product.

FIG. 2 is a view showing the compressive strength of a cured body.

FIG. 3 shows the results of a sulfuric acid exposure test.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 111: 20 C04B 111: 20 111: 23 111: 23 (72) Inventor Masaki Ishimori Daisakuji, Sakura City, Chiba Prefecture Chome 4-2 Taiheiyo Cement Co., Ltd.Sakura Laboratory (72) Inventor Toshiyuki Saeki 2-4-2 Daisaku, Sakura City, Chiba Prefecture Onoda Development Laboratory Co., Ltd. (72) Inventor Akinori Hamanaka Daisaku Sakura City, Chiba Prefecture F-term (Reference) 4G012 PA03 PA09 PA29 PA29 PB03

Claims (6)

[Claims] (A) The molar ratio of (A) CaO / SiO ₂ is 0.1.
10 to 1.20 molten slag powder 10 to 85% by weight,
(B) A curable composition containing 5-40% by weight of water glass in solid content and (C) 5-70% by weight of alumina cement. 2. The molten slag powder has a fineness of 20 in specific surface area.
00-15000cm ^TwoThe curability according to claim 1, which is / g.
Composition. (D) blast furnace slag, converter slag,
The curable composition according to claim 1, wherein the curable composition contains 1 to 30% by weight of a binder selected from dephosphorized slag, desilicated slag, and desulfurized slag. 4. The method according to claim 1, wherein (E) the alkali metal salt is 1 to 1
4. The curable composition according to claim 1, which contains 5% by weight. 5. A curable composition comprising (F) 30 to 300% by weight of the curable composition according to claim 1. 6. A cured product obtained by mixing the curable composition according to claim 1 with water and curing.