JP2003165763A - Fiber reinforced acid resistant concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acid resistant concrete having an increased bending strength. <P>SOLUTION: (g) Fiber is mixed to the acid resistant concrete containing (a) 10-85 wt.% fused slag powder whose CaO/SiO<SB>2</SB>molar ratio is 0.10-1.20, (b) 5-50 wt.% alkali silicate as solid content, (c) 1-30 wt.% alkali metals salt, (d) 5-50 wt.% alumina cement, (e) 2-40 wt.% binder selected among a blast furnace slag, a converter slag, a dephosphorized slag, a desilicinized slag and a desulfulized slag and (f) fine aggregate, coarse aggregate and water. <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 fiber-reinforced acid-resistant concrete which is fiber-reinforced to increase bending strength.

[0002]

2. Description of the Related Art With the recent improvement of sewerage system, the spread rate of sewage sludge and the amount of sewage sludge collected at sewage treatment plants are increasing year by year. Especially in large cities where the sewerage penetration rate is high, the amount of sewage sludge and municipal waste is large, so it is difficult to secure a landfill site that can be continuously used in the future when landfill disposal is performed by reducing the amount of incineration. Further, a large amount of heavy metals are contained in the incineration ash of sewage sludge and municipal solid waste, and when these are directly landfilled, there is a risk of environmental pollution such as elution of heavy metals.

In order to solve such a problem, sewage sludge molten slag obtained by converting these into molten slag (hereinafter referred to as sewage slag)
And municipal waste melting slag (hereinafter referred to as urban waste slag)
This method is expected to be a promising treatment method in the future, because the volume is about half that of incinerated ash and the heavy metal is immobilized on the glassy slag.

As a method of utilizing these molten slags, powdered sewage slag or municipal waste slag, alkali silicate,
Acid-resistant concrete using alkali metal salts, alumina cement, binder, aggregate and water has been proposed.
This acid-resistant concrete is characterized by having excellent acid resistance as compared with conventional concrete using cement (hereinafter referred to as cement concrete).

At present, the durability of concrete products in the event of an earthquake has been emphasized. This is because a concrete member is subjected to a bending load or a shearing load at the time of an earthquake, and the member may be greatly damaged. Therefore, increasing the bending strength of concrete is one factor for improving seismic resistance, and the same applies to acid-resistant concrete. As a method of increasing this bending strength, it is possible to increase the thickness of the concrete member and the ratio of reinforcing bars in the concrete member (hereinafter referred to as the reinforcing bar ratio), but if the thickness of the member is changed, the conventional formwork Since it cannot be used, there is a problem in terms of cost because the mold must be newly built. Further, an increase in the reinforcing bar ratio causes a problem that the reinforcing bars in the formwork become overcrowded, making it difficult to fill the concrete and degrading the formability.

As a method for increasing the bending strength of cement concrete, a method of mixing fibers is known. According to this method, the bending strength is increased, but the fluidity of the concrete is deteriorated by mixing the fibers into the concrete. This is considered to be because the amount of water that contributes to the fluidity decreased due to the absorption of the kneading water when the fibers had water absorbability, and the moisture etc. adhered to the fiber surface when the fibers had no water absorbency. It is considered that the liquidity is lowered by doing so. Therefore, in cement concrete, the maximum mixing ratio of fibers is about 3% by volume, and if the mixing ratio of fibers is higher than this, the fluidity of the concrete is remarkably reduced, and problems occur in mixing, pouring, molding, etc. , If greater bending strength is needed,
It was necessary to consider using it together with another method such as increasing the ratio of reinforcing bars, which was a big problem in terms of cost and productivity.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. The object of the present invention is to mix fibers to increase the flexural strength of an acid resistant material. The purpose of the present invention is to provide a high-performance concrete, and further to significantly increase the amount of fibers mixed in as compared with cement concrete.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have conducted extensive studies and found that the bending strength can be increased by mixing fibers into acid-resistant concrete. . Further, they have found that the amount of fibers mixed in can be higher than that of cement concrete, and completed the present invention.

That is, in claim 1, (a) 10 to 85% by weight of molten slag powder having a CaO / SiO ₂ molar ratio of 0.10 to 1.20, and (b) 5 to 40% by weight of alkali silicate as a solid content. , (C) 1 to 30% by weight of alkali metal salts, (d) 5 to 50% by weight of alumina cement, (e) a binder selected from blast furnace slag, converter slag, dephosphorization slag, decalcification slag and desulfurization slag. 2-40
It is characterized in that (g) reinforcing fibers are mixed in acid-resistant concrete containing wt% and (f) aggregate / water.
The reinforcing fiber (g) may be either long fibers or short fibers. This makes it possible to provide concrete capable of increasing bending strength. The second aspect is characterized in that 0.1 to 10.0% by volume of the reinforcing fiber of the component (g) is mixed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The molten slag powder of the component (a) used in the present invention is a raw material such as sewage sludge, incinerators such as municipal waste, clay and limestone so that the molar ratio of CaO / SiO ₂ is 0.10 to 1.20.
The slag is obtained by crushing the slag obtained by melting at a high temperature a mixture of two or more kinds and mixing at a high temperature. Of these, waste molten slag such as sewage slag and municipal waste slag is preferable in terms of economy and waste recycling. (a)
The molar ratio of CaO / SiO ₂ component is a 0.10 to 1.20, 0.10
A range of up to 0.60 is particularly preferred. When this molar ratio is less than 0.10, the reactivity of the composition is low, and a cured product having sufficient initial strength and being durable cannot be obtained. On the other hand, when this molar ratio exceeds 1.20, calcium hydroxide remains in the cured product, which forms dihydrate gypsum in the presence of sulfuric acid, causing expansion failure, resulting in insufficient acid resistance in the cured product. become.

The fineness of CaO / SiO _{2 as} the component (a) is preferably 2000 to 15 in terms of specific surface area from the viewpoint of strength development of the cured product.
000 cm ² / g, more preferably 3000 to 15000 cm ² / g, particularly preferably 4000 to 15000 cm ² / g. The specific surface area is 1
Even those having a content of more than 5000 cm ² / g can be suitably used in the present invention, but the upper limit is 15 because the grinding is costly and not economical.
It is 000 cm ² / g. On the other hand, this is 2000 cm ² / g
If it is less than the above range, the hydration activity is poor and the strength of the cured product may be insufficient. The specific surface area referred to here is a value measured by the Blaine method (JIS R 5201).

The molten slag powder of component (a) is preferably mixed in the cement composition in an amount of 10 to 85% by weight, more preferably 25 to 60% by weight. If it is less than 10% by weight, the acid resistance is lowered, and if it exceeds 85% by weight, the viscosity of concrete becomes high.

The alkali silicate as the component (b) is not particularly limited, and commercially available ones can be used. In addition to water glasses No. 1, No. 2, No. 3 and JIS No. It can also be used in products that do not conform to the JIS standard that are manufactured and sold by the manufacturer, and each can be used alone or in combination of two or more types.

The above-mentioned component (b), an alkali silicate, is contained in the cement composition in an amount of 5 to 40% by weight, preferably 20% by weight in terms of solid content.
~ 30% by weight. If this 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 the casting operation may become difficult.

Regarding the alkali metal salts of the component (c),
Sodium metasilicate, sodium orthosilicate, powdered sodium silicate 1
No., sodium hydroxide, potassium hydroxide, lithium hydroxide, etc., but sodium metasilicate, sodium orthosilicate, and sodium hydroxide are preferable. By cutting the -Si-O-Si- chain in component (b) with an alkali, the viscosity is reduced, which improves workability, and the addition of alkali stimulates the molten slag and cures it. Has the function of promoting The alkali metal salts may be used alone or in combination of two or more.

The above component (c) is added to the cement composition in an amount of 1
It is desirable to add ~ 30 wt%, especially 1-10 wt%
Incorporation reduces viscosity and provides sufficient strength. When the amount added exceeds 30% by weight, the effect of enhancing the strength is obtained, but the effect of decreasing the viscosity is not enhanced, and especially when an excessive amount of alkalinity is added, the surface of the cured product becomes white. It is not preferable because it may cause flowering.

The alumina cement as the component (d) is not particularly limited, and commercially available ones can be used, but preferably
It is preferable that the content of CaO / Al ₂ O ₃ is high. For example, Lafarge's "Secal 51BTF", Denki Kagaku Kogyo's "Alumina Cement No. 1" and the like can be preferably used.

The above-mentioned (d) component alumina cement may be added to the cement composition in an amount of preferably 5 to 50% by weight, particularly preferably 10 to 45% by weight. If it is less than 5% by weight, sufficient compressive strength cannot be obtained, and if it exceeds 50% by weight, good acid resistance cannot be obtained.

The binder as the component (e) is not particularly limited, and commercially available ones can be used. For example, blast furnace slag can be used, and the fineness thereof is 4000 cm ² / g or more in terms of specific surface area by the Blaine method. Are preferred.

The amount of the binder as the component (e) added may be in the range of 2 to 40% by weight in the cement composition, but a preferable range is 5 to 20% by weight. If it is less than 2% by weight, sufficient early strength cannot be obtained, and if it exceeds 40% by weight, sufficient acid resistance cannot be obtained.

Therefore, the CaO / SiO ₂ molar ratio of the component (a), the mixture of the components (a) and (e) is 1.20 or less, preferably 0.80 or less, more preferably 0.60 or less from the viewpoint of acid resistance. It is a range. Furthermore, the total amount of component (d) and component (e) is 7-75.
%, Especially 15 to 50% by weight is preferable because it has good acid resistance and good workability.

The aggregate of the component (f) mixed with the above cement composition is not particularly limited as long as it has acid resistance, and examples thereof include quartz rock, andesite, basalt, crushed ceramics and the like. . Further, granular or lump-shaped waste molten slag can be used as an aggregate. Then, it is preferable to use a fine aggregate and a coarse aggregate in combination as the aggregate, and the aggregate is 200 with respect to the cement composition.
It is preferably used in an amount of from about 800% by weight, particularly from 400 to 600% by weight.

Further, in the present invention, workability is improved by adding an appropriate amount of water and kneading. Water is preferably used in a proportion of 25 to 60% by weight, particularly 30 to 45% by weight, based on the cement composition.

Mix in the acid resistant concrete
The fiber as the component (g) is not particularly limited, but short fibers or long fibers are preferably used alone or in combination of two or more kinds. The short fiber has a diameter of 0.3 to 0.6 mm and a length of 20 to 40 mm, and examples thereof include steel fiber, polyester fiber, acrylic fiber and vinylon fiber.
The long fibers refer to those having a fiber length not less than the above short fibers, and examples thereof include polyester fibers and nylon fibers. Also,
It is possible to mix 0.1 to 10% by volume, but 0.3 to 5.0
Volume% is preferred. If the content is less than 0.1% by volume, the increase in bending strength due to the incorporation of fibers is not so much observed, and 10.0
When the content is more than the volume%, it becomes difficult to mix.

The amount of the component (g) mixed with the fiber according to the present invention is increased as compared with the cement concrete because the fiber-reinforced acid-resistant concrete is physically impaired in fluidity of the concrete by mixing the fiber into the concrete. However, by mixing the alkali silicate, which is the component (b) in the fiber-reinforced acid-resistant concrete, with kneading water,
This is because the viscosity is increased and the absorption of water on the fiber and the adhesion of water on the surface of the fiber are prevented.

The method for molding the fiber-reinforced acid-resistant concrete of the present invention is not particularly limited, and any conventionally used method such as centrifugal force molding, cast molding, pressure molding, extrusion molding, and instant demolding can be used. You can do it.

After molding, the fiber-reinforced acid-resistant concrete of the present invention is obtained by heating and curing. The heating and curing method is not particularly limited, but steam curing is preferable, and as the steam curing method, it is preferable to carry out at 40 to 90 ° C. for 2 hours or more, particularly at 65 to 80 ° C. for 2 hours or more, and further preferable , 65-80 ° C for 5-10 hours.

The fiber-reinforced acid-resistant concrete of the present invention is
Pipe, gutter, manhole, box culvert, joint groove,
Products such as segments, blocks, fishing reefs, flat plates, trusses, retaining walls, storage tanks, stencil forms, flumes, etc. can be used. Further, in these products, the fiber-reinforced acid-resistant concrete may be entirely used, but the fiber-reinforced acid-resistant concrete may be used only for a part of the constituent members.

[0029]

The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
The symbols used in Examples 1 to 10 and Comparative Example 1 and the symbols used in Table 1 are shown below. (a) Component: Sewage sludge molten slag Fine powder: CaO / SiO ₂ molar ratio 0.4
6, specific surface area 5000 cm ² / g (b) component: alkali silicate: water glass (c) component: alkali metal salt: sodium metasilicate (d) component: alumina cement: Lafarge Secar 5
1BTF (e) Component: Blast furnace slag: Specific surface area 4000 cm ² / g (f) Component: Fine aggregate: Katabama City, Ibaraki Prefecture Katataiwa Coarse aggregate: Kasama City, Ibaraki Prefecture Katataiwa Water: Tap water (g) component : Aramid fiber (I): Density 1.39 g / cm ³ Glass fiber (alkali resistant) (II): Density 2.70 g / cm ³ Vinylon fiber (III): Density 1.30 g / cm ³ Stainless steel fiber (IV): Density 7.80 g / cm ³ W / P: water-solids ratio

Test Example 1 (Examples 1 to 10 and Comparative Example 1) The concrete kneaded with the composition of Examples 1 to 10 and Comparative Example 1 shown in Table 1 was 100 × 100 × under vibration.
It was poured into a 400 mm prismatic formwork. After that, steam curing was carried out at 75 ° C for 10 hours to prepare a concrete specimen. Using the obtained concrete specimen, a test was performed at a material age of 7 days in accordance with JIS A 1106 (concrete bending strength test method). The results are also shown in Table 1.

[0031]

[Table 1]

From the results shown in Table 1, the bending strengths of Examples 1 to 9 were higher than those of Comparative Example 1. Therefore, it was confirmed that the bending strength increases in various fibers in the range of 0.1% by volume to 10% by volume of the fiber. Also, when the fibers were mixed in an amount of more than 10% by volume, it became difficult to mix the fiber-reinforced acid-resistant concrete and to form the specimen.

[0033]

Industrial Applicability According to the present invention, it is possible to provide a fiber-reinforced acid-resistant concrete which can increase the fiber mixing rate as compared with cement concrete and can obtain higher bending strength.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C04B 14:38 C04B 14:38 Z 16:06) 16:06 A 111: 20 111: 20 111: 23 111 : 23 F term (reference) 4G012 PA07 PA17 PA19 PA24 PA26 PA29 PA30 PB03 PB06 PC04 PC06 PC11 PC12 PD03

Claims (2)

[Claims] 1. (a) 10 to 85% by weight of molten slag powder having a CaO / SiO ₂ molar ratio of 0.10 to 1.20, (b) 5 to 40% by weight of alkali silicate in solid content, and (c) alkali. 1 to 30% by weight of metal salts, 5 to 50% by weight of (d) alumina cement, and (e) 2 to 40% by weight of a binder selected from blast furnace slag, converter slag, dephosphorization slag, decalcification slag and desulfurization slag. , And (f)
Fiber-reinforced acid-resistant concrete characterized by mixing (g) reinforcing fibers in acid-resistant concrete containing aggregate and water. 2. The fiber-reinforced acid-resistant concrete according to claim 1, wherein 0.1 to 10.0% by volume of the reinforcing fiber of the component (g) is mixed.