JP4318418B2 - Cement composition - Google Patents

Description

【００２５】
【発明の効果】
本発明のセメント組成物は六価クロムの低減能力を有し、アルミネート系化合物の含有量が多い廃棄物利用型セメントを主体としているにも関わらず、これを用いたコンクリートのスランプロスを小さくすることができる。
また、高炉徐冷スラグの有効利用や都市型廃棄物の減容にもなるなどの効果を奏する。[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a cement composition used in the civil engineering and construction industry.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.
[0002]
[Prior art and its problems]
In recent years, since the concrete durability problem has been greatly highlighted, the water / cement ratio of concrete has a major impact on durability. Therefore, high-performance water reducing agents and high-performance AE water reduction are aimed at reducing the unit water volume. The frequency of use of agents has increased rapidly and guidelines have been issued.
However, there is a problem that the more the unit water amount is reduced, the greater the change in consistency with time and the lower the fluidity, and there is currently no drastic measure for this problem.
[0003]
Recently, so-called eco-cement, which is produced using urban waste as a raw material, has been in the limelight, and there are great expectations from the viewpoint of reducing environmental impact and establishing a waste volume reduction system. (Kaihei 07-165446, JP-A-10-279332, and JP-A-11-199301).
However, this ecocement contains a large amount of calcium aluminate compounds 3CaO · Al ₂ O ₃ and 11CaO · 7Al ₂ O ₃ · CaCl ₂ compared to ordinary Portland cement, resulting in a decrease in fluidity. Has the problem of being prominent.
[0004]
The fluidity is extremely important because it is deeply related to the occurrence of construction defects, and it is necessary to hold it from the raw plant, transport it to the construction site, and maintain the fluidity for a certain period of time.
However, when it is involved in some trouble or traffic jam at the site, the elapsed time greatly exceeds the predetermined time, and the fluidity of the concrete often falls outside the predetermined standard.
In such a case, there is no method other than performing a so-called refluidization treatment in which a high-performance AE water reducing agent or the like is additionally added and fluidized again.
However, the fact is that this refluidization process can only be performed by skilled engineers.
In this way, today, there is a strong demand for the development of concrete that is excellent in fluidity retention performance even when using waste-use cement that is produced using municipal waste incineration ash as a raw material and has a large decrease in fluidity. .
[0005]
On the other hand, chromium, which is contained in a small amount in cementitious materials, is of great interest as a hexavalent chromium that adversely affects the human body from the viewpoint of environmental problems.
In particular, the component management of waste-use cement manufactured using municipal waste incineration ash as a raw material is strictly performed.
However, it is extremely difficult to completely grasp the amount of chromium derived from the raw material, and it cannot be said that the hexavalent chromium countermeasure is perfect only by component management.
Therefore, it is considered preferable to implement further measures against hexavalent chromium.
[0006]
Hexavalent chromium has been proposed to reduce the amount of elution with a reducing agent or adsorbent.
However, these materials are too expensive to be used in the cement concrete field, and the actual situation is that they are rarely used.
[0007]
As a result of repeated earnest efforts, the present inventor uses a waste-use cement produced from municipal waste incineration ash as a raw material, so that there is little decrease in fluidity and the ability to reduce hexavalent chromium. The present inventors have found that a product can be obtained and have completed the present invention.
[0008]
[Means for Solving the Problems]
That is, the present invention contains a waste-use cement manufactured using municipal waste incineration ash as a raw material and sulfur present as non-sulfate sulfur in an amount of 0.5% or more, a vitrification rate of 30% or less, and a brain specific surface area of 2,000. A cement composition containing 5 to 50 parts of the blast furnace annealed slag powder in 100 parts of a cement composition containing 8,000 cm ² / g of blast furnace annealed slag powder.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0010]
Waste-based cement (hereinafter referred to as eco-cement) manufactured using urban waste as a raw material in the present invention is a general term for cement manufactured using municipal waste incineration ash or sewage sludge as a main raw material. There is no particular limitation.
There are two types of ecocement: normal ecocement and fast-cure ecocement.
Ordinary eco-cement has a very low chlorine content, and the main component of aluminate compounds is 3CaO · Al ₂ O ₃ ; fast-curing eco-cement has a high chlorine content and the main component of aluminate compounds is 11CaO · Al. ₂ O ₃ · CaCl ₂ is different.
[0011]
The blast furnace slow-cooled slag powder (hereinafter referred to as slow-cooled slag powder) used in the present invention is a powder of blast furnace slag that has been cooled and crystallized.
The components of slow-cooled slag powder have the same composition as granulated blast furnace slag. Specifically, SiO ₂ , CaO, Al ₂ O ₃ , MgO, etc. are the main chemical components, and other components , TiO ₂ , MnO, Na ₂ O, S, P ₂ O ₅ , Fe ₂ O _{3 and the} like.
In addition, as a compound, the main component is so-called melilite, which is a mixed crystal of gelenite 2CaO · Al ₂ O ₃ · SiO ₂ and akermanite 2CaO · MgO · 2SiO ₂ , other than that, dicalcium silicate 2CaO · SiO ₂ , and lanknite 3CaO · 2SiO _2, and wollastonite calcium silicates, such as CaO · SiO _2, calcium magnesium silicate, such as Merubinaito 3CaO · MgO · 2SiO ₂ and Monte celite CaO · MgO · SiO _2, anorthite _{CaO · Al 2 O 3 · 2SiO} 2 , Leucite (K ₂ O, Na ₂ O) · Al ₂ O ₃ · SiO ₂ , spinel MgO · Al ₂ O ₃ , magnetite Fe ₃ O ₄ , sulfides such as calcium sulfide CaS and iron sulfide FeS, etc. May include.
These sulfides are exposed on the surface of the particles by pulverizing the slowly cooled slag, and are eluted as thiosulfate ions and sulfite ions when in contact with water, and exhibit hexavalent chromium reduction performance.
[0012]
In the present invention, among the slow-cooled slag powder, for example, sulfur existing as non-sulfuric sulfur such as sulfide, polysulfide, sulfur, thiosulfuric acid, and sulfurous acid (hereinafter simply referred to as non-sulfuric sulfur). Slowly-cooled slag powder obtained by pulverizing a product containing 0.5% or more is used. If the non-sulfuric sulfur is less than 0.5%, the effects of the present invention, that is, the fluidity retention performance and the hexavalent chromium reduction performance may not be sufficiently obtained. Non-sulfuric sulfur is preferably 0.5% or more, more preferably 0.7% or more, and most preferably 0.9% or more.
The amount of non-sulfuric sulfur is determined by quantifying the total sulfur amount, single-body sulfur amount, sulfide sulfur amount, thiosulfate sulfur amount, and sulfate sulfur amount (sulfur trioxide) by the method of Yamaguchi and Ono. In addition, the amount of sulfate sulfur (sulfur trioxide) and the amount of sulfide sulfur can also be determined by quantifying by the method defined in JIS R 5202 ("Situation analysis of sulfur in blast furnace slag", Naoji Yamaguchi, (See Ono, Akira, Steel Research, No. 301, pp. 37-40, 1980).
[0013]
The vitrification rate of the slowly cooled slag powder used in the present invention is preferably 30% or less, more preferably 10% or less. If the vitrification rate exceeds 30%, sufficient fluid retention performance and hexavalent chromium reduction performance may not be obtained.
When the vitrification rate is high, the slag powder having a high vitrification rate compared to the slow-cooled slag that is crystalline has less elution of thiosulfate ions, etc., even though it contains almost the same amount of non-sulfuric sulfur. The reduction performance of valent chromium is small.
The vitrification rate (X) referred to in the present invention is determined as X (%) = (1−S / S ₀ ) × 100. Here, S is the main crystalline compound in slow-cooled slag powder obtained by powder X-ray diffraction method (mixed crystal of gelenite 2CaO · Al ₂ O ₃ · SiO ₂ and akermanite 2CaO · MgO · 2SiO ₂ ) S ₀ represents the area of the main peak of melilite after the slowly cooled slag powder was heated at 1,000 ° C. for 3 hours and then cooled at a cooling rate of 5 ° C./min.
[0014]
Although the fineness of the slowly cooled slag powder is not particularly limited, it is preferably 2,000 to 8,000 cm ² / g or more, more preferably 4,000 to 8,000 cm ² / g, in terms of the specific surface area of the brane (hereinafter referred to as the brane value). 5,000 to 8,000 cm ² / g is most preferable. If the brain value is less than 2,000 cm ² / g, the effects of the present invention, that is, the fluidity retention performance and the hexavalent chromium reduction performance may not be obtained sufficiently, and the powder is ground to exceed 8,000 cm ² / g. In this case, the pulverization power is increased, which is uneconomical, and the gradually cooled slag powder is likely to be weathered, which may cause deterioration of quality over time.
It is possible to control the elution amount of thiosulfate ions and sulfite ions by this fineness. By increasing the fineness, the initial hexavalent chromium reduction performance is enhanced, and conversely, by reducing the fineness, long-term It is possible to provide a wide range of hexavalent chromium reduction performance.
[0015]
Although the usage-amount of slow-cooled slag powder is not specifically limited, Usually, 5-50 parts are preferable in 100 parts of cement compositions which consist of ecocement and slow-cooled slag powder, and 10-30 parts are more preferable. If it is less than 5 parts, the effects of the present invention may not be sufficiently obtained, and if it is used in excess of 50 parts, strength development may be deteriorated.
[0016]
In the present invention, in addition to the cement composition of the present invention, a conventional cement can be used in combination.
As cement, various Portland cements such as normal, early strength, ultra-early strength, low heat, and moderate heat, various mixed cements in which blast furnace slag, fly ash, or silica is mixed with these Portland cements, limestone powder, etc. The filler cement etc. which were mixed are mentioned, The 1 type (s) or 2 or more types of these can be used.
[0017]
The fineness of the cement composition of the present invention is not particularly limited because it depends on the purpose and application of use, but it is usually preferably 2,000 to 8,000 cm ² / g in terms of brain value, and 3,000 to 5,000 cm ² / g is more preferred. If it is less than 2,000 cm ² / g, strength development may not be sufficient, or the effects of the present invention, that is, fluidity retention performance and hexavalent chromium reduction effect may not be sufficiently obtained, 8,000 cm ² / g. If it exceeds, workability may deteriorate.
[0018]
In the present invention, in addition to cement composition, aggregates such as sand and gravel, admixture materials such as blast furnace granulated slag powder, limestone powder, fly ash, and silica fume, water reducing agent, AE water reducing agent, high performance water reducing agent, High performance AE water reducing agent, antifoaming agent, thickener, rust inhibitor, antifreeze agent, shrinkage reducing agent, polymer emulsion, setting modifier, clay minerals such as bentonite, anion exchanger such as hydrotalcite, etc. Of these, one or more of them can be used within a range that does not substantially impair the object of the present invention.
[0019]
In the present invention, the mixing method of each material is not particularly limited, and the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance.
Any existing apparatus can be used as the mixing apparatus, and for example, a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer can be used.
[0020]
【Example】
Hereinafter, further description will be given based on experimental examples of the present invention.
[0021]
Experimental example 1
Eco cement and various slowly cooled slag powders (slag) were blended as shown in Table 1 to prepare cement compositions.
Next, concrete having a unit cement composition amount of 350 kg / m ³ , a unit water amount of 175 kg / m ³ , s / a = 46%, and an air amount of 4.5 ± 1.5% was prepared, and the change of slump with time was measured.
Moreover, the hexavalent chromium reduction capability of the cement composition was evaluated. The results are also shown in Table 1.
A high-performance AE water reducing agent was used so that the slump value of concrete would be 18 ± 1.5 cm.
[0022]
<Materials used>
Cement I: Normal type Ecocement, commercially available products, C _{3 S} content of 45.3% C _{2 S} content of 16.0% C _{3 A} content 14.9%, and C ₄ AF content 11.9%
Cement b: rapid-eco cement, commercial product, C _{3 S} content of 48.4% C _{2 S} content of _{8.5%, C 11 A 7 ·} CaCl 2 content of 16.2%, and C ₄ AF content 6.7%
Slag a: Slowly cooled slag powder, brain value 2,000cm ² / g, vitrification rate 5%, specific gravity 3.00, non-sulfate sulfur 0.9%
Slag b: Slowly cooled slag powder, brain value 4,000 cm ² / g, vitrification rate 5%, specific gravity 3.00, non-sulfate sulfur 0.9%
Slag c: Slowly cooled slag powder, brain value 5,000cm ² / g, vitrification rate 5%, specific gravity 3.00, non-sulfuric sulfur 0.9%
Slag d: Slowly cooled slag powder, brain value 6,000cm ² / g, vitrification rate 5%, specific gravity 3.00, non-sulfate sulfur 0.9%
Slag e: Slowly cooled slag powder, brain value 8,000cm ² / g, vitrification rate 5%, specific gravity 3.00, non-sulfate sulfur 0.9%
Slag f: Slowly cooled slag powder, slag d immersed in water and aged to 0.7% non-sulfate sulfur, brain value 6,000cm ² / g, vitrification rate 5%, specific gravity 3.00
Slag g: Slowly cooled slag powder, slag d dipped in water and aged to 0.5% non-sulfuric sulfur, brain value 6,000cm ² / g, vitrification rate 5%, specific gravity 3.00
Slag h: Slowly cooled slag powder, brain value 6,000cm ² / g, vitrification rate 10%, specific gravity 2.97, non-sulfate sulfur 0.7%
Slag i: Slowly cooled slag powder, brain value 6,000cm ² / g, vitrification rate 30%, specific gravity 2.94, non-sulfate sulfur 0.5%
Slag j: Blast furnace granulated slag powder, brain value 6,000cm ² / g, vitrification rate 95%, specific gravity 2.90, non-sulfate sulfur 0.1 %
Fine aggregate: Sand from Himekawa, Niigata Prefecture, specific gravity 2.62
Coarse aggregate: Himekawa, Niigata, crushed stone, specific gravity 2.64
High-performance AE water reducing agent: polycarboxylic acid, commercially available water: tap water [0023]
<Measurement method>
Slump loss: The slump value was measured according to JIS A 1101, and the slump value after 60 minutes was subtracted from the slump value after kneading to obtain the slump loss value.
Hexavalent chromium residual concentration: To confirm the hexavalent chromium reduction ability of the cement composition, dilute the hexavalent chromium standard solution to prepare a solution with a hexavalent chromium concentration of 50 mg / l. Evaluation was performed by putting 10 g of each cement composition in 50 cc, stirring, solid-liquid separation after 7 days, and measuring the residual hexavalent chromium concentration in the liquid phase. However, the residual concentration of hexavalent chromium was measured by ICP emission spectroscopic analysis according to JIS K 0102.
[0024]
[Table 1]

[0025]
【The invention's effect】
The cement composition of the present invention has the ability to reduce hexavalent chromium, and despite being mainly composed of waste-use cement with a high content of aluminate compounds, it reduces the slump loss of concrete using this. can do.
In addition, there are effects such as effective use of blast furnace slow cooling slag and volume reduction of municipal waste.

Claims (1)

Waste-use cement manufactured using municipal waste incineration ash as a raw material, and 0.5% or more of sulfur present as non-sulfate sulfur, vitrification rate of 30% or less, Blaine specific surface area 2,000 to 8,000cm ² / g A cement composition comprising 5 to 50 parts of the blast furnace slow-cooled slag powder in 100 parts of a cement composition comprising the blast furnace slow-cooled slag powder .