JP2003267770A - Method of manufacturing autoclaved lightweight concrete (alc) and material for manufacturing alc - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively utilize a by-product fine powder yielded in recovering aggregate from waste concrete. <P>SOLUTION: In manufacturing an autoclaved lightweight concrete by casting a mixture comprising a siliceous material and a calcareous material as major ingredients with the addition of a proper amount of a foaming agent into a mold, foaming, hardening for a required period of time to form a semi-plastic body and curing it in an autoclave, a by-product fine powder yielded in recovering aggregate from waste concrete after heated at 100-500°C is used as a part of the materials. Besides, a raw material for manufacturing an autoclaved lightweight concrete is formed by a substance comprising the by-product fine powder. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ALC and a raw material for production thereof, which uses, as a raw material, fine powder produced as a by-product when an aggregate is recovered from waste concrete.

[0002]

2. Description of the Related Art A typical method for producing ALC is to use siliceous raw materials and calcareous raw materials as main raw materials, to which other raw materials such as gypsum are added, and further appropriate amounts of water, metal powder such as aluminum, and additives. Slurry kneaded by adding, etc., is poured into a formwork in which reinforcing bars are arranged as necessary to foam,
A method is used in which a semi-plastic material obtained by curing for a desired time is taken out from the mold, cut into desired dimensions, inserted into an autoclave, and steam-cured at high temperature and high pressure. As the siliceous raw material, for example, crushed silica stone or silica sand is used, and as the calcareous raw material, for example, quick lime or cement is used.

Further, slag, fly ash, etc., which are industrial by-products or industrial wastes, are also effectively used as a raw material in the production of the above ALC.

On the other hand, it is also a social problem to effectively use the concrete waste material generated when the concrete structure is dismantled. As for the aggregates (coarse aggregates and fine aggregates) contained in the concrete waste, it is possible to recover high quality aggregates. However, the by-product fine powder generated when the aggregate is collected is used as a soil improving material and the like, but further development of its application is desired.

Then, the inventors of the present invention have conducted extensive studies to further develop the use of the by-product fine powder, and have found that the by-product fine powder can be effectively used as a raw material for the ALC. It was

[0006]

The present invention has been made based on the above findings, and ALC which can effectively utilize as a raw material the fine powder produced as a by-product generated when the aggregate is recovered from the concrete waste material. It is an object of the present invention to provide a manufacturing method and a raw material for manufacturing.

[0007]

In order to solve the above problems, an ALC manufacturing method according to the invention of claim 1
Using a raw material mainly composed of siliceous raw material and calcareous raw material, adding a suitable amount of a foaming agent to this, injecting it into a mold to foam it, and curing it for a desired time to a semi-plasticized material by an autoclave A method for producing an ALC for carrying out a curing treatment, characterized in that fine powder produced as a by-product when an aggregate is recovered from a concrete waste material after being heated to 100 to 500 ° C. is used as a part of the raw material. .

The method for producing ALC according to claim 2 is the method according to claim 1, wherein the by-product fine powder is used in an amount of less than 60% by mass of all raw materials containing the by-product fine powder. It is characterized by being.

For manufacturing ALC according to the third aspect of the invention
The raw material is concrete after heating to 100-500 ° C
A using by-product fine powder generated when collecting aggregate from waste wood
The by-product fine powder, which is a raw material for LC production, contains 1% of CaO.
Contains 0-30% by mass, SiO₂35 to 60 mass%
Have, Al₂O₃2.0 to 10% by mass, Fe ₂
O₃0.1 to 2.0% by mass, Na₂0.5 for O
~ 2.0% by mass, K₂O will be 5% by mass or less
And the balance consists of unavoidable impurities.
It is a sign.

Claim 1 or 2 configured as described above
In the ALC manufacturing method according to the invention described in
Since it has been confirmed that the by-product fine powder generated when the aggregate is recovered from the concrete waste material after being heated to 0 to 500 ° C. actually contains the following components, the above-mentioned by-product fine powder is It can be used effectively and in large quantities as a main raw material for siliceous raw materials and calcareous raw materials. That is, the ranges of the respective components of a plurality of lots of by-product fine powder recovered from a plurality of concrete waste materials are summarized as follows.

CaO (calcium oxide) as a calcareous raw material
10 to 30% by mass, SiO as a siliceous raw material₂
35 to 60 mass% of (silicon dioxide), Al₂O₃(Al oxide
(Minium) is 2.0 to 10 mass%, Fe₂O₃(Iron oxide)
0.1-2.0 mass%, Na₂O (sodium oxide) is 0.
5 to 2.0 mass%, K₂O (potassium oxide) is 5 mass% or less
The balance below is unavoidable impurities. However, from one lot
If the fine powder obtained by sampling is taken, the above CaO, SiO ₂, Al₂
O₃, Fe₂O₃, Na₂OK₂Total of O and unavoidable impurities is 10
It goes without saying that it will be 0%.

Looking at the by-product fine powder in one lot, there is a certain relationship that when CaO increases, SiO ₂ decreases, and when CaO decreases, SiO ₂ increases. That is, when CaO is less than 10%, the proportion of cement hydrate is reduced, and as a main component of the coarse-grained portion of the aggregate.
Since the proportion of SiO ₂ increases, the total amount of Ca
The recommended value of O / SiO ₂ ratio (hereinafter referred to as “Ca / Si ratio”) of 0.4 to 0.6 (a value close to 0.5) cannot be obtained, and the reactivity of CaO and SiO ₂ is reduced. Will be reduced. Therefore, if CaO is contained at 10% or more as described above, the by-product fine powder can be effectively used as a raw material for ALC.
Further, when CaO is more than 30%, the proportion of cement hydrate increases, and SiO ₂ as the main component of the coarse-grained portion of the aggregate
In this case as well, the Ca / Si ratio of all raw materials including fine powder of by-products cannot be 0.4 to 0.6, and the reactivity between CaO and SiO ₂ will be reduced. . Therefore, if CaO is 30% or less as described above, ALC
It can be said that it can be effectively used as a raw material. From the above, the by-product fine powder can be used effectively and in large quantities as a raw material for ALC.

It should be noted that the concrete waste material is 100 to 500
The heating to ℃ makes the cement paste dehydrated and fragile without adversely affecting the aggregates, so that high quality aggregates can be easily and reliably taken out by, for example, scouring. This is to obtain by-product fine powder that is reliably dehydrated and finely pulverized. That is, heating to 100 ° C. or higher is not effective at weakening the cement paste of the concrete waste material at less than 100 ° C., so that the high-quality aggregate in which the cement paste and the mortar are reliably removed is obtained. This is because it is difficult to obtain the finer by-product fine powder as well as it is difficult to obtain. Moreover, there is also a drawback that it takes a lot of time to dehydrate the cement paste or the like. Also, 500 ℃
The reason for heating to the following temperature is that there is a possibility that the aggregate in the concrete waste material may be altered or deteriorated at a temperature higher than 500 ° C. And considering these points, the concrete waste material is 300 to 350 ° C.
It is more preferable to heat to.

In the method for producing ALC using the concrete waste material according to the second aspect of the present invention, since the amount of the by-product fine powder used is less than 60% by mass of all the raw materials containing the by-product fine powder, all the raw materials The recommended Ca / Si ratio of 0.4
~ 0.6 can be obtained. Therefore, it is possible to prevent the compressive strength of ALC from being lowered after the autoclave curing treatment. It should be noted that the reason why the content is less than 60 mass% is that when the content is 60 mass% or more, the Ca / Si ratio of all raw materials is 0.4
This is because it becomes difficult to secure 0.6 and the compressive strength sharply decreases.

Since the raw material for ALC production according to the third aspect of the present invention comprises fine powder by-products having the above-mentioned components, 60 mass% of all raw materials for producing ALC.
Even if it is used in a ratio of less than 0.4, the Ca / Si ratio of all the raw materials can be secured at 0.4 to 0.6, and the compressive strength can be maintained at the same level as that of normal ALC. Therefore,
A large amount of by-product fine powder can be effectively used.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

In the method for producing ALC shown in this embodiment, other raw materials such as gypsum dihydrate are added to the main raw materials of siliceous raw material and calcareous raw material, and by-product fine powder is also added as a raw material, and an appropriate amount of water, Slurry kneaded with a foaming agent such as aluminum, additives, etc. is poured into a mold in which reinforcing rebars are arranged as necessary, foamed, and cured into a semi-plastic material for a desired time. It is a method of taking out from the above-mentioned mold, cutting it to a desired size, inserting it into an autoclave, and curing it with steam at high temperature and high pressure. By this method, lightweight cellular concrete as ALC can be manufactured. As the siliceous raw material, crushed silica stone or silica sand is used, and as the calcareous raw material, quick lime, cement or the like is used.

The by-product fine powder is a concrete waste material generated when a concrete structure is dismantled at 100 to 500 ° C.
After being heated to a high temperature, the concrete waste is put into a mill or the like to collect coarse aggregate and fine aggregate, which are collected by a bag filter or the like. It should be noted that heating the concrete waste material to 100 to 500 ° C. makes the cement paste dehydrated and fragile without adversely affecting the aggregate, for example, by grinding with a mill to obtain high quality aggregate. This is because it is possible to easily and surely take out, and to obtain by-product fine powder that is surely dehydrated and finely pulverized. That is, heating to 100 ° C. or higher is not effective at weakening the cement paste of the concrete waste material at less than 100 ° C., so that the high quality aggregate in which the cement paste and the mortar are surely removed is used. This is because it is difficult to obtain the finer by-product fine powder as well as it is difficult to obtain. Also, 500 ℃
The reason why it is heated to the following temperature is that there is a possibility that the aggregate in the concrete waste material may be deteriorated or deteriorated at a temperature higher than 500 ° C. And considering these points, the concrete waste material is 300 to 350 ° C.
It is more preferable to heat to.

The by-product fine powder is replaced with the main raw material of the siliceous raw material and the calcareous raw material, and the raw material such as gypsum, so that less than 60 mass% of the total raw material including the fine by-product is used. It has become.

The by-product fine powder is a calcium silicate hydrate (nCaO.mSiO ₂ ) produced mainly by hydration of cement.
・ H ₂ O) and slaked lime (Ca (OH) ₂ ), calcium carbonate (CaCO ₃ ) which is a carbonate of slaked lime, and coarse aggregate and fine aggregate partially crushed Has become.

The above-mentioned calcium silicate hydrate and slaked lime can be crystallized into tobermorite by autoclave curing and contribute to the strength development as ALC. further,
Since the calcium silicate hydrate is heated at 100 to 500 ° C., the adhered water is completely removed, and the crystal water is also partially removed. Further, since the adhered water is removed, the powder raw material does not condense, or does not cool during feeding, and is easy to handle.

Since part of the crystal water is removed, a hydration reaction occurs again when it comes into contact with water, and a hardening reaction as cement can be expected. Therefore, even if a part of the cement, which is the main raw material of ALC, is replaced with fine powder of by-products,
It has the feature that the strength of the cured product (semi-plastic or raw cake) before curing in the autoclave can be prevented.

The above-mentioned calcium carbonate does not have a particularly bad influence in the production of ALC. Rather, when there is an alkaline component (Na) mixed from the coarse aggregate and the fine aggregate, a part of the calcium carbonate is crystallized to tobermorite crystallization. You can also contribute.

The by-product fine powder produced by pulverizing a part of the coarse aggregate and the fine aggregate is mainly composed of α-quartz and alumina components. Since these are constituent components of alumina-substituted tobermorite, which is the main constituent mineral of ALC, they contribute to the production of tobermorite by autoclave curing.

The components of the plurality of lots of by-product fine powder recovered from a plurality of concrete waste materials are summarized as follows.

CaO: 10 to 30 mass% SiO ₂ : 35 to 60 mass% Al ₂ O ₃ : 2.0 to 10 mass% Fe ₂ O ₃ : 0.1 to 2.0 mass% Na ₂ O: 0. 5 to 2.0 mass% K ₂ O: 5 mass% or less Inevitable impurities: balance

Then, look at one lot of by-product fine powder.
And, when CaO increases, SiO₂Less, less CaO
When it comes to SiO₂There is a certain relationship that there will be more. sand
That is, if CaO is less than 10%, cement hydrate
The proportion of the
SiO₂Since the ratio of
O / SiO₂The recommended value of the ratio (hereinafter referred to as "Ca / Si ratio")
0.3 to 0.9, which is described later, is preferably 0.4 to 0.6.
No longer available, CaO and SiO₂Decrease in reactivity with
become. Therefore, as described above, CaO content of 10% or more is included.
If it is rare, the by-product fine powder can be used effectively as a raw material for ALC.
It can be used. Also, when CaO exceeds 30%, the
The proportion of ment hydrate increases and the main component of the coarse-grained part of the aggregate
SiO as a minute₂Since the ratio of
The Ca / Si ratio of all raw materials including by-product fine powder is 0.3 to 0.
9, preferably 0.4-0.6 is no longer obtained and CaO
And SiO ₂Reactivity with will decrease. Therefore,
As described above, if CaO is 30% or less, it is regarded as a raw material for ALC.
And can be effectively used.

From the above, it is understood that the by-product fine powder obtained by heat-polishing can be effectively used as a raw material for ALC.

The components of the by-product fine powder sampled from one lot are as shown in Table 1 by-product fine powder A and by-product fine powder B in consideration of the loss on ignition. That is, the above
_{CaO, SiO 2, Al 2 O} 3, Fe 2 O 3, Na 2 O, K 2 O, and other total (inevitable impurities) and an ignition loss becomes 100 wt%.
Note that the ignition loss is a decrease in mass that occurs when ignited, and occurs when the ALC raw material is heated at about 1000 ° C.

ALC takes into account the reactivity of raw materials in order to secure the physical properties of the product after curing in an autoclave,
The above-mentioned Ca / Si ratio, which is the molar ratio of CaO / SiO ₂ , is 0.3-
It is desirable to adjust to 0.9, preferably 0.4 to 0.6. That is, the chemical composition of the by-product fine powder is analyzed in advance (see Table 1), and the Ca / Si ratio after the addition of the by-product fine powder as a raw material is adjusted to fall within the above range.

It should be noted that the compressive strength of ALC after completion as a product decreases as the amount of by-product fine powder added increases. However, by increasing the density of ALC, it is possible to prevent the compressive strength from decreasing. You can However, if the amount of by-product fine powder added is 60% by mass or more, the density will be JIS A
Even if the pressure is increased to 550 kg / m ³ or more specified in 5416, the compressive strength will drop sharply. For this reason,
The amount of by-product fine powder used is 60% of the total raw materials including this by-product fine powder.
It is preferable to set it to be less than mass%.

ALC using the above-mentioned fine powder of by-product as a part of the raw material can be manufactured by using the same equipment as a normal ALC.

According to the method for producing ALC configured as described above, SiO _{2 is} added to the fine powder produced as a by-product when the coarse aggregate and the fine aggregate are recovered from the concrete waste material after heating to 100 to 500 ° C. Is contained in an amount of 35 to 60% by mass and CaO is contained in an amount of 10 to 30% by mass. Therefore, the by-product fine powder can be reused effectively and in large amounts instead of the main raw materials of the siliceous raw material and the calcareous raw material. In addition, the amount of by-product fine powder used is 60
Since it is less than mass%, it is possible to prevent the compression strength of the ALC from decreasing.

[0034]

EXAMPLES Next, examples of the present invention will be described.

1. Experimental Results Table 1 shows the results of analyzing the chemical components of by-product fine powder added as a raw material for ALC, and describes the analysis results of by-product fine powders A and B sampled at different manufacturing times of aggregate. . Tables 2 and 3 show the experimental results and the like for ALC. That is, Table 2 is
Conventional example and 1-1 to 1-4 with addition of fine powder A and B by-products
Table 3 shows the contents (mass%) of the raw materials, the Ca / Si ratio, the compressive strength (N / mm ² ) and the density kg / m ³ for the Examples 2-1 to 2-4. The experimental results and the like are described. The compressive strength and the density are measured on the block portion after the autoclave curing in the portion not containing the reinforcing bar described later. In addition, the content rate of the by-product fine powder is A including this by-product fine powder.
It is shown as a ratio to all raw materials for producing LC.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

The Ca / Si ratio was calculated using the following formula. Ca / Si = ((92C1 + 63C2 + MC3) / (92S1 + 21S2 + MS3)) x (5
6/60) However, C1 is the content rate of quick lime (mass%) C2 is the content rate of cement (mass%) C3 is the content rate of CaO in the by-product fine powder (mass%) S1 is the content of silica stone Rate (mass%) S2 is the content rate (mass%) of cement, the same as C2 above S3 is the content rate (mass%) of SiO ₂ in the by-product fine powder M is the by-product fine powder in each example The content (mass%) 56 is the molecular weight of CaO 60, and the molecular weight of SiO ₂ .

92C1 means the content rate (% by mass) of CaO in quicklime. 63C2 means the content rate (mass%) of CaO in cement. MC3 means the content rate (mass%) of CaO in the by-product fine powder when added as a raw material. 92S1 means the content rate (mass%) of SiO ₂ in silica stone. 21S2 means the content rate (mass%) of SiO _{2 in} the cement. MS3 means the content rate (mass%) of SiO _{2 in} the by-product fine powder when added as a raw material.

2. Blending method of raw materials When blending raw materials, the CaO and SiO ₂ contents of Table 1 are taken into consideration, and CaO and SiO are added as by-product fine powder.
₂ and the Ca / Si ratio calculated by the sum of CaO in quicklime and SiO _{2 in} silica that are input as raw materials do not change significantly, so that by-product fine powder, quicklime, silica, gypsum dihydrate, cement, etc. The input amount was adjusted.

3. Method for producing ALC A slurry prepared by adding an appropriate amount of water, a foaming agent of aluminum powder, and the like to the above raw materials and kneading the mixture is adjusted to 45 ° C., and a steel mold having a size of 150 × 600 × 60 cm in which a reinforcing bar is arranged is placed inside. Inject to foam. After the injection, a semi-plastic material that was cured for a predetermined time was cut with a piano wire, and then autoclave-cured at 180 ° C. under a saturated steam pressure of 10.5 atm.

4. Consideration The compressive strength of each of Examples 1-1 to 1-3 and 2-1 to 2-3 has the density increased with an increase in the amount of the fine powder produced as a by-product, so that the fine powder produced by-product is added at all. It was possible to obtain a result equal to or higher than that of the conventional example. Also,
Regarding the compressive strength of each of Examples 1-4 and 2-4,
There is no problem at all, as it exceeds the specified value of JIS A 5416. However, as can be seen from the results of each of Examples 1-4 and 2-4, the amount of the by-product fine powder added was 60% by mass.
It becomes equal to or larger than, be set to a density greater than defined by the scope range of less than 450 kg / m ³ to more than 550 kg / m ³ is the density in JIS A 5416, the expression of the compressive strength is lowered, the compression The strength will drop sharply. 5. Conclusion By setting the addition amount of the by-product fine powder to less than 60% by mass of all raw materials including the by-product fine powder, it is possible to obtain ALC having no problem in strength. By setting the addition amount of by-product fine powder to 50% by mass or less of all raw materials including this by-product fine powder, JIS A 5416
Within the range of the density defined by, it is possible to obtain an ALC having a strength equal to or higher than that in the case where the by-product fine powder is not added.

[0044]

As described above, claim 1 or 2
ALC using the concrete waste material according to the invention described in 1.
According to the manufacturing method of, the by-product fine powder generated when the aggregate is recovered from the concrete waste material heated to 100 to 500 ° C. contains SiO ₂ as a siliceous material in an amount of 35 to 60 mass%,
Since CaO as a calcareous raw material is contained in an amount of 10 to 30% by mass, the by-product fine powder can be used effectively and in large amounts as a main raw material for ALC.

According to the ALC manufacturing method of the second aspect of the present invention, since the amount of the by-product fine powder used is less than 60% by mass, it is possible to prevent the compression strength from decreasing.

According to the raw material for ALC production according to the third aspect of the present invention, since SiO ₂ and CaO are contained in the above-described proportions, less than 60% by mass of the total raw material for producing ALC is contained. Even if it is used in a ratio, a compressive strength equivalent to that of normal ALC can be secured. Therefore, a large amount of by-product fine powder can be effectively used.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koichi Imazawa             1117-11, Seki-cho, Suzuka-gun, Mie Sumitomo Metals             Mine Sipolex Co., Ltd.             Within (72) Inventor Hisashi Tachiyashi             1-3-25 Koishikawa, Bunkyo-ku, Tokyo Koishikawa Univ.             Kuni Building Mitsubishi Materials Corporation Environmental Lisa             Uccle Business Center (72) Inventor Hirokazu Shima             1-3-25 Koishikawa, Bunkyo-ku, Tokyo Koishikawa Univ.             Kuni Building Mitsubishi Materials Corporation Environmental Lisa             Uccle Business Center F-term (reference) 4G012 PA03 PA30 PE06                 4G019 HA02 HA05 HC02

Claims (3)

[Claims] 1. A semi-plastic material is obtained by using a raw material mainly composed of a siliceous raw material and a calcareous raw material, adding a suitable amount of a foaming agent to the mold, and foaming the mixture to cure for a desired time. A method for producing an ALC in which a cured product is subjected to a curing treatment by an autoclave, wherein by-product fine powder produced when collecting aggregate from concrete waste after heating to 100 to 500 ° C. is used as a part of the above raw material. A method for producing an ALC, comprising: 2. The method for producing an ALC according to claim 1, wherein the amount of the by-product fine powder used is less than 60% by mass of all raw materials containing the by-product fine powder. 3. A raw material for ALC production using by-product fine powder produced when aggregate is recovered from a concrete waste material after being heated to 100 to 500 ° C., wherein the by-product fine powder contains 10 to 30 CaO. Mass% content, S
35 to 60 mass% of iO ₂ is contained, and Al ₂ O ₃ is 2.0
10 to 10% by mass, Fe ₂ O ₃ 0.1 to 2.0% by mass, Na ₂ O 0.5 to 2.0% by mass, K
_A raw material for ALC production, containing ₂ O in an amount of 5% by mass or less, and the balance being inevitable impurities.