JP2011148667A - Cement composition using modified molten slag fine aggregate, production method thereof and cement hardened material using the cement composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement composition using modified molten slag fine aggregate, which avoids the entrainment or the pop-out phenomenon of excess bubbles when molten slag is used as the fine aggregate, which has improved compressive strength and suppressed neutralization, and to provide a production method of the cement composition and a cement hardened material using the cement composition. <P>SOLUTION: The cement composition using the modified molten slag fine aggregate and the cement hardened material using the cement composition each contains 50-100 mass% modified molten slag to total mass of the fine aggregate, wherein the modified molten slag is obtained by immersing the modified molten slag in magnesium silicofluoride solution having 5-30 mass% concentration for 30 min to 2 hr and after that, by removing the magnesium silicofluoride component stuck to the modified molten slag. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cement cement composition using a modified molten slag fine aggregate, a method for producing the same, and a cement cured product using the cement composition, and more particularly, entrainment or popping of excess bubbles caused by the molten slag. The present invention relates to a cement composition using a modified molten slag subjected to stabilization treatment to prevent an out phenomenon as a fine aggregate, a method for producing the same, and a hardened cement using the cement composition.

Molten slag is an inorganic material obtained by solidifying incinerated ash discharged from a waste incinerator, sludge discharged from a sewage treatment plant, etc. at 1200 ° C. or higher.
Conventionally, such molten slag has been utilized for paving fine aggregates, roadbed materials, concrete fine aggregates, freeze-preventing sand, ceramic materials, artificial stone materials, and the like.

For molten slag originating from general waste or sewage sludge, silicon dioxide (SiO ₂ ), calcium oxide (CaO), aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), iron oxide (Fe ₂ O ₃₎ ), Phosphorus oxide (P ₂ O ₅ ), and other trace amounts of harmful substances.
Since the molten slag has a single particle size of approximately 5 mm or less, its use as a fine aggregate for concrete is promising.
Therefore, JIS A 5031 (Non-patent Document 1) stipulates the use of molten slag as a fine aggregate for concrete, including calcium oxide (CaO), iron oxide (Fe ₂ O ₃ ), and harmful substances. The content and elution amount are described.

However, when using molten slag as a fine aggregate for concrete, the chemical components defined in the above JIS A 5031 are calcium oxide (CaO) that is a direct expansion component and sulfur that generates a secondary expansion component. It is only a compound (S or SO ₃ ), and further iron oxide (Fe ₂ O ₃ ) in consideration of prevention of contamination due to rust. The JIS A 5031 also describes the content and elution amount of harmful substances.

Aluminum oxide (Al ₂ O ₃ ) contained in the molten slag reacts with calcium hydroxide and water in the concrete to generate hydrogen gas, which causes excess bubbles to be entrained in the obtained concrete. A 5031 does not specifically define this amount.
Therefore, when molten slag is used as a fine aggregate for concrete, surplus bubbles are entrained in the concrete and the amount of air contained is increased.

  Further, even when the content of calcium oxide (CaO) specified by JIS A 5031 is satisfied, if CaO is present on the surface of concrete or mortar in the order of several millimeters, the expansion reaction between CaO and water Thus, a pop-out phenomenon that peels off the surface concrete or mortar occurs.

  Therefore, for the reasons described above, although molten slag is defined by JIS as a fine aggregate for concrete, there is a problem that it has not been put into practical use for obtaining a hardened cement.

JIS A 5031

The object of the present invention is to solve the above-mentioned problems, and when molten slag is used as a fine aggregate for use, it is possible to avoid entrainment of excess bubbles and a pop-out phenomenon, a cement composition, a production method thereof, and It is to provide a hardened cement product using the cement composition.
Furthermore, the objective of this invention is providing the cement hardened | cured material using the cement composition, its manufacturing method, and the said cement composition which increase a compressive strength and the neutralization is suppressed in addition to the said subject. It is.
Furthermore, in addition to the above-mentioned problems, the object of the present invention is to put the practical use as a material for obtaining a cement composition and a cement cured product using the composition by effectively reusing molten slag as waste. Another object of the present invention is to provide a cement composition, a method for producing the same, and a hardened cement product using the cement composition.

In order to solve the above problems, the present invention stabilizes molten slag by dissolving Al ₂ O ₃ and CaO, which are foaming components and expansion components, contained in the molten slag and solidifying them as harmless substances. By applying the treatment and containing the stabilized molten slag as a fine aggregate in a predetermined amount, entrainment of excess bubbles and pop-out phenomenon are manifested in the obtained cement composition and the hardened cement using the composition. It has been found that this can be avoided. Further, by using a predetermined amount of the molten slag subjected to the stabilization treatment as a fine aggregate, strength enhancement and neutralization suppression of the hardened cement material of the present invention are achieved.

The cement composition using the modified molten slag of the present invention removes the magnesium silicofluoride component adhering to the modified molten slag after being immersed in a magnesium silicofluoride solution having a concentration of 5 to 30% by mass for 30 minutes to 2 hours. The modified molten slag is contained in 50 to 100% by mass in the total mass of the fine aggregate.
Preferably, in the cement composition of the present invention, the magnesium fluorosilicate solution has a pH of 2 to 3.
More preferably, in the cement composition of the present invention, the modified molten slag obtained by removing the magnesium fluorosilicate component adhering to the modified molten slag by washing with water or heating at 100 ° C. or more is used as the fine aggregate. It is characterized by containing.

In the method for producing a cement composition using the modified molten slag of the present invention, the molten slag is immersed in a magnesium fluorosilicate solution having a concentration of 5 to 30% by mass for 30 minutes to 2 hours, and then the obtained modified molten slag is obtained. The modified molten slag from which the magnesium silicofluoride component adhering to the surface is removed is blended at a ratio of 50 to 100% by mass in the total mass of the fine aggregate.
Preferably, in the method for producing a cement composition using the modified molten slag of the present invention, the pH of the magnesium silicofluoride solution is set to 2 to 3.
More preferably, in the method for producing a cement composition using the modified molten slag according to the present invention, the magnesium fluorosilicate component adhering to the modified molten slag is removed by washing with water or heating at 100 ° C. or higher. It is characterized by that.

  The hardened cement material using the modified molten slag fine aggregate of the present invention is a hardened cement material cured using the above-described cement composition of the present invention.

  The modified molten slag refers to molten slag obtained by immersing molten slag in the magnesium silicofluoride solution, and the cement composition refers to a mortar composition or a concrete composition, and further cement hardening. A thing shall mean mortar hardened | cured material and concrete hardened | cured material.

In the cement composition using the modified molten slag of the present invention and the cured cement using the composition, Al ₂ O ₃ which is a foaming component originally present in the molten slag and CaO which is an expansion component disappear. Therefore, when a predetermined amount of modified molten slag is used as a fine aggregate in a cement composition such as concrete or mortar and a hardened cement using the composition, the resulting cement composition and the composition are used. It is possible to eliminate the entrainment of excess bubbles and the occurrence of pop-out phenomenon in the cured cement. Moreover, the intensity | strength increase of the cement hardened | cured material obtained using the cement composition of this invention can be aimed at, and neutralization can be suppressed.
Moreover, the manufacturing method of the cement composition using the modified molten slag of the present invention can efficiently manufacture the cement composition of the present invention.
Therefore, since the molten slag subjected to the stabilization treatment according to the present invention can be effectively used as concrete aggregate in concrete or mortar, the molten slag as waste can be effectively reused.

  The cement composition using the modified molten slag of the present invention and the cured product cured using the composition are modified and melted after being immersed in a magnesium fluorosilicate solution having a concentration of 5 to 30% by mass for 30 minutes to 2 hours. The modified molten slag from which the magnesium silicofluoride component adhering to the slag is removed is contained at 50 to 100% by mass in the total mass of the fine aggregate.

First, the modified molten slag contained in the cement composition of the present invention and the cured product using the composition will be described.
The modified molten slag is obtained by subjecting the molten slag, which is a waste material, to the following modification and stabilization treatment. Specifically, the molten slag is added to a magnesium fluorosilicate solution having a concentration of 5 to 30% by mass. It is obtained by dipping for 2 minutes to modify for 2 hours and removing the magnesium fluorosilicate component adhering to the modified molten slag.

That is, modified molten slag in which Al ₂ O ₃ as a foaming component and CaO as an expansion component that exist in molten slag are eliminated by immersing molten slag fine aggregate in a magnesium fluorosilicate solution having a specific concentration for a certain period of time. Can be obtained.

When molten slag is immersed in the magnesium silicofluoride solution, Al ₂ O ₃ and CaO contained in the molten slag are dissolved and removed by chemically reacting with the magnesium silicofluoride solution, and are reformed and stabilized. In the case where the modified molten slag is used as a fine aggregate, entrainment of surplus bubbles generated when the cement composition and the cement cured product using the composition are used with the molten slag before modification, The pop-out phenomenon is not generated, and further, strength enhancement and neutralization suppression are achieved.

The density | concentration of the magnesium silicofluoride solution which immerses molten slag is 5-30 mass%, and pH of this magnesium silicofluoride solution is 2-3.
When the concentration is less than 5% by mass, the pH of the solution cannot be set to the desired range, and Al ₂ O ₃ and CaO in the molten slag cannot be sufficiently dissolved.
In addition, from the viewpoint of the solubility of magnesium silicofluoride, it is virtually impossible to prepare the solution at a concentration exceeding 30% by mass, and the pH of the solution cannot be less than 2.

The time for immersing the molten slag in the magnesium silicofluoride solution is 30 minutes to 2 hours at room temperature (25 ° C.).
If it is less than 30 minutes, the components of CaO and Al ₂ O ₃ cannot be reliably dissolved, and the molten slag cannot be sufficiently modified. When it is contained as a fine aggregate, the cement composition and the composition As a result, excessive bubbles are entrained and pop-out phenomenon occurs in the hardened cement material.
On the other hand, when the immersion time exceeds 2 hours, the modified molten slag aggregates and solidifies, and therefore, when used as a fine aggregate, a crushing operation is required. When the pulverization operation is used, extra work is required when used as an aggregate, and the original particle size is impaired due to residual aggregates and generation of pulverized powder, making it unsuitable for use as a fine aggregate.

The molten slag after the immersion treatment with the magnesium fluorosilicate solution does not contain CaO or Al ₂ O ₃ , and a molten slag that has been sufficiently modified can be obtained.
Since excess magnesium silicofluoride is adhered to the modified molten slag, it is necessary to remove the excess magnesium silicofluoride.
As a removal method, the excess magnesium silicofluoride component is washed or decomposed by washing with water or by performing a heat treatment at 100 ° C. or higher.
This is because the magnesium silicofluoride component has the effect of delaying the hydration of the cement, and therefore when the modified molten slag is contained by performing the cleaning operation or the heat treatment, water for obtaining a cement cured product is obtained. This is to prevent sum delay.

When the modified molten slag is used as a fine aggregate, the modified molten slag is desirably blended in a range of 50 to 100% by mass with respect to the total mass of the fine aggregate.
If the fine aggregate replacement ratio of the modified molten slag is less than 50% by mass, excess air entrainment and pop-out phenomenon of the cement composition and a cured cement using the composition can be avoided, but strength enhancement and neutrality can be avoided. This is because it is not possible to suppress the conversion.
The fine aggregate other than the modified molten slag is not particularly limited, and is a fine aggregate with a relatively fine particle size such as river sand, mountain sand, land sand, crushed sand, sea sand, silica sand No. 3-7, Alternatively, fine powders such as silica stone powder and limestone powder can be used.

  The type of cement constituting the cement composition of the present invention is not particularly limited. For example, various portland cements such as ordinary and early strength, mixed cements of blast furnace cement, silica cement and fly ash cement, white portland cement and Various cements available on the market such as alumina cement can be exemplified, and these can be used alone or in combination.

In addition, blast furnace slag powder, fly ash, silica fume, limestone powder, quartz powder, dihydrate gypsum, hemihydrate gypsum, type I, type II and type III anhydrous gypsum, alone or in combination, are used for the cement. Thus, an appropriate amount can be blended.
Furthermore, any known coarse aggregate such as gravel or crushed stone can be used as the coarse aggregate.
If necessary, the concrete or mortar can be mixed with concrete admixtures such as an expansion material, a shrinkage reducing agent, an AE agent, and an AE water reducing agent within a range not impairing the effects of the present invention.

  In addition, the amount of the kneading water for preparing the cement composition in the present invention can be changed depending on the type and blending of the materials to be used, and therefore is not uniquely determined. 25-60 mass% is a common compounding quantity by cement ratio.

By curing and curing the cement composition of the present invention prepared as described above, a cement cured product using the modified molten slag of the present invention is obtained.
The curing method is not particularly limited, and any method such as underwater curing or steam curing can be used.

  In this way, the cement composition using the modified molten slag in an amount of 50 to 100% by mass with respect to the total mass of the fine aggregate and the hardened cement using the composition cause entrainment of excess bubbles and occurrence of a pop-out phenomenon. Thus, strength enhancement and neutralization suppression are achieved, the molten slag is effectively reused, and the molten slag can be put to practical use in a cement cured product.

The present invention is illustrated by the following examples and comparative examples, but is not limited thereto.
Materials used : Magnesium fluorosilicate: Industrial chemicals manufactured by Morita Chemical Co., Ltd. Molten slag: Molten slag having the chemical components and physical properties shown in the following Table 1. The molten slag is specified in JIS A 5031 The longest diameter is 5 mm or less.

・ Water: Tap water, Cement: Ordinary Portland cement (Sumitomo Osaka Cement Co., Ltd.)
・ Normal fine aggregate: Land sand (from Kakegawa, Shizuoka Prefecture)
・ Coarse aggregate: A mixture of No. 5 crushed stone (Iwase Iwase) and No. 6 crushed stone (Iwase Iwase)
(Mass ratio 50:50)
-AE water reducing agent: Pozzolith 78S (manufactured by BASF Pozzolith)
-AE agent: (air amount adjusting agent): Micro Air 101 (manufactured by BASF Pozzolith)

(Examples 1-12, Comparative Examples 1-15)
Using the magnesium silicofluoride and the molten slag of Table 1, the treatment shown in Table 2 was performed to produce 13 types of molten slag fine aggregates (MS1 to MS13).

Specifically, an aqueous magnesium silicofluoride solution having each concentration and pH shown in Table 2 below was prepared using the above magnesium silicofluoride raw material. Here, SK-620PH manufactured by Sato Meter Co., Ltd. was used for pH measurement.
Next, the molten slag of Table 1 is immersed in each magnesium silicofluoride aqueous solution for the immersion time shown in Table 2 below, and then the molten slag after immersion is taken out with each magnesium silicofluoride solution, and sufficiently with water. Washed.

After the treatment, the presence or absence of Al ₂ O ₃ and CaO in the molten slag fine aggregate was measured for the presence or absence of a peak using a powder X-ray analyzer (Ultima IV, manufactured by Rigaku Corporation). Table 2 also shows the results of the presence or absence of detection.
When a peak is detected, “present” is indicated, and when no peak is detected, “not present” is indicated.
Table 2 also shows the presence / absence (visual observation) of aggregation of the molten slag particles obtained after the above treatment.

Using each molten slag fine aggregate shown in Table 2 and each of the materials used, each material was kneaded by a biaxial forced kneading mixer with the formulation shown in Table 3 below to prepare each cement composition. However, since MS5, MS9, and MS13 shown in Table 2 were coagulated and solidified, they could not be used for preparing the cement composition.
Each cement composition obtained by uniformly kneading was cast into a predetermined steel mold, and after one day had passed from the casting (room temperature: 20 ° C.), the mold was removed and molded. A hardened cement was obtained.

For each cement composition obtained in each of the above Examples and Comparative Examples, the amount of air according to JIS A 1128, the compression strength according to JIS A 1108 for each cement cured product, and the accelerated neutralization depth according to JIS A 1153 It was measured. Furthermore, the occurrence of pop-out on the surface of each cured cement was visually observed.
However, in Table 4, with respect to the concrete composition of the comparative example whose air amount is not within the range of 4.5 ± 0.5, when the composition is used for visual observation of compressive strength, accelerated neutralization and pop-out, the concrete composition The product was defoamed by adding micro air 404 manufactured by BASF Pozzolith Co., Ltd., and the air amount was adjusted to a range of 4.5 ± 0.5, and then measured. These measurement results are shown in Table 4.

As shown in Table 4 above, the cement composition of the example in which the modified molten slag subjected to the stabilization treatment according to the present invention was used in an amount of 50% by mass or more based on the total mass of the fine aggregate and the composition were used. The hardened cement material had almost the same amount of air as the cement composition (concrete composition) of Comparative Example 1 prepared using ordinary fine aggregates without using molten slag as fine aggregates, and pop-outs were also generated. It was not confirmed.
Further, the cement cured product of the example of the present invention showed an increase in compressive strength after 28 days of age with respect to Comparative Example 1, and a significant decrease in the neutralization depth after 91 days of age.
From the above, the disappearance of Al ₂ O ₃ and CaO, which is the cause when modified molten slag is used as a fine aggregate, eliminates excess bubble entrainment and pop-out phenomenon, and improves strength and neutralization. It means that suppression was obtained.

On the other hand, the cement compositions of Comparative Examples 2 to 5, Comparative Examples 8 to 9, and Comparative Examples 12 to 13 and the cured cements using the compositions are subjected to the modification and stabilization treatment of the molten slag used as fine aggregates. Insufficient, not only does the amount of air increase and pop-outs occur, but also the compressive strength is small and the neutralization depth is slightly larger than the hardened cement material (hardened concrete material) of Comparative Example 1. became.
Moreover, although the cement hardened | cured material of Comparative Examples 6, 7, 10, 11, 14, and 15 used the molten slag which performed the modification | stabilization stabilization process concerning this invention, the usage-amount becomes fine aggregate total mass. On the other hand, since it is less than 50% by mass, it is impossible to achieve strength enhancement or significant neutralization suppression.

  The cement composition using the modified molten slag of the present invention and the cement cured product using the cement composition can be applied as any cement cured body in the field of architecture and civil engineering. In addition, the molten slag, which is waste, can be effectively used.

Claims (7)

  The modified molten slag from which the magnesium silicofluoride component adhering to the modified molten slag after being immersed in a magnesium silicofluoride solution having a concentration of 5 to 30% by mass for 30 minutes to 2 hours is removed is 50 to 50% of the total mass of fine aggregate. A cement composition using a modified molten slag fine aggregate, characterized by containing 100% by mass.   The cement composition using the modified molten slag fine aggregate according to claim 1, wherein the magnesium silicofluoride solution has a pH of 2 to 3.   The cement composition according to claim 1 or 2, wherein the modified molten slag obtained by removing the magnesium silicofluoride component adhering to the modified molten slag by washing with water or heating at 100 ° C or higher is contained as a fine aggregate. A cement composition using a modified molten slag fine aggregate.   The modified molten slag obtained by immersing the molten slag in a magnesium silicofluoride solution having a concentration of 5 to 30% by mass for 30 minutes to 2 hours and then removing the magnesium silicofluoride component adhering to the obtained modified molten slag, A method for producing a cement composition using a modified molten slag fine aggregate, comprising blending at a ratio of 50 to 100% by mass in the total mass of the fine aggregate.   The method for producing a cement composition according to claim 4, wherein the pH of the magnesium silicofluoride solution is 2 to 3, wherein the modified molten slag fine aggregate is used.   The method for producing a cement composition according to claim 4 or 5, wherein the magnesium silicofluoride component adhering to the modified molten slag is removed by washing with water or heating at 100 ° C or higher. A method for producing a cement composition using slag fine aggregate.   A hardened cement product using a modified molten slag fine aggregate hardened by using the cement composition according to any one of claims 1 to 3.