JPH0753245A - High-ferrite hydraulic admixture, its production and mixed cement using the admixture - Google Patents

Abstract

PURPOSE:To obtain a marine cement excellent in sulfate resistance by adding a lime source, an alumina source and an iron oxide source to a slag powder generated dephosphorizing pig iron, firing the mixture and mixing the obtained high-ferrite hydraulic admixture in cement. CONSTITUTION:An iron oxide source is added to a slag powder generated in dephosphorizing pig iron, a lime source and an alumina source and mixed so that Fe2O3/(CaO+Al2O3)<=1/5(mol/mol). The mixture is fired at 1000-1200 deg.C for 6-150min, cooled and then crushed to the Blaine specific surface of about 2000-5000cm<2>/g to obtain a high-ferrite hydraulic admixture consisting of 30-50wt.% ferrite, 15-45wt.% beta-dicalcium silicate, 1-5wt.% calcium fluoroaluminate, 2-10wt.% fluoroapatite and inevitable components. The admixture is mixed in normal portland cement by 10-30wt.% to obtain a mixed cement of a low heat generation excellent in sulfate resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic admixture material having a high ferrite phase content, a method for producing the same, and a mixed cement using the hydraulic admixture material. In particular, it is produced by dephosphorizing pig iron in an iron making process. Slag (hereinafter referred to as slag)
The present invention relates to a hydraulic admixture material containing a ferrite phase at a high content, a method for producing the same, and a mixed cement using the hydraulic admixture material.

[0002]

2. Description of the Related Art A hydraulic material has been known for a long time, and a typical example is ordinary Portland cement which is used in large amounts for general concrete construction. Also,
With the expansion of applications, there are early-strength Portland cements with enhanced characteristics, moderate heat Portland cements, and sulfate-resistant Portland cements. However, even those Portland cements are not yet sufficient as Portland cements with added properties corresponding to the application, while:
There is a demand for even more excellent hydraulic materials, including inexpensive manufacturing.

On the other hand, the slag generated by dephosphorizing pig iron in the iron-making process contains 1% of phosphorus (P), which is a harmful component, even though it contains useful components such as CaO in the iron-making process. Since it contains ~ 3%, there is a limit to the recycling use. In addition, several percent of free (f) exists for use as civil engineering materials such as land reclamation materials and road materials.
ree) It is necessary to prevent the expansion and collapse phenomenon due to CaO, and for that purpose, there is a problem that it is necessary to carry out field accumulation (generally referred to as aging) for about one year to achieve stabilization. However, since it is inexpensive as a raw material, its use as the above-mentioned cement raw material has been studied and several methods have been proposed in order to develop effective utilization of slag.

Japanese Patent Laid-Open No. 63-206336 discloses a calcium fluoroaluminate (11CaO.7Al ₂ O ₃ .CaF) utilizing CaO and CaF ₂ contained in slag (referred to as dephosphorization slag in the publication). _A method for producing a quick-hardening cement, in which ₂ ) is produced at a lower temperature than before, is disclosed.

Further, in Japanese Unexamined Patent Publication No. 1-115819, slag (which is referred to as dephosphorization slag in the publication) is added with aluminum residual ash and gypsum, so that Irwin (3CaO.3Al ₂ O _{3 can be} produced at low cost and low temperature. · CaSO ₄₎ manufacturing method to produce is disclosed.

Further, JP-A-2-302347 discloses that β-dicalcium silicate, CaF _{2 and the} like contained in slag (referred to as dephosphorization slag in the publication) are used to produce β-dicalcium silicate and calcium fluoro. A method for producing a cement containing aluminate and the like, which has high initial strength and low exothermicity, is disclosed.

On the other hand, Japanese Patent Laid-Open No. 50-10314 discloses a method for producing iron cement. In this manufacturing method, blast furnace slag / converter slag is used as the main raw material, and limestone is added to the mixture, and the mixture is calcined at 1300 to 1450 ° C. The limestone and calcining heat amount are significantly reduced, and the initial strength development is excellent.

[0008]

The above-mentioned ordinary Portland cement is alite (3CaO.SiO ₂ ), belite (β-2CaO.SiO ₂ ), and an aluminate phase (3CaO.Al ₂ O ₃ ) which is a void phase. , Ferrite phase (4CaO ・ Al ₂ O ₃・ Fe ₂ O ₃ ) and gypsum (Ca
It is composed of SO ₄ .2H ₂ O) and is known as an excellent hydraulic material.

[0009] Further, the early-strength Portland cement with emphasized characteristics is a cement with a high amount of alite and high initial strength development, and the moderate heat Portland cement is a low hydration heat cement with a increased amount of belite. , Sulfate resistant Portland cement is a high sulfate resistant cement with a reduced amount of aluminate phase.

Further, cement using slag is also highly evaluated as having improved properties thereof.
That is, JP-A-63-206336 discloses a method for producing a quick-hardening cement which is produced at a low temperature, and JP-A-2-302.
Japanese Patent No. 347 describes a method for producing cement having high initial strength and low exothermicity.

However, a hydraulic material which has characteristics as a hydraulic material, particularly emphasizes the sulfate resistance, and which can be manufactured at low cost, has not been obtained yet. Nothing is described about the sulfate resistance property of the above-mentioned slag. Sulfate resistant Portland cement is generally done by reducing the amount of aluminate phase in the cement mineral.

The aluminate phase, when gypsum is present,
Ettringite (3CaO ・ Al ₂ O ₃ / 3CaSO ₄
・ 32H ₂ O) and monosulfate (3CaO ・ Al ₂
O ₃ · CaSO ₄ · 12H ₂ O) and other hydrates are formed. In particular, ettringite is an expansive mineral, and it is safe to form it in the very early hydration process (before hardening) where space still exists, but after hardening, sulfate ions are supplied from the outside. In that case, the monosulfate converted from the ettringite becomes ettringite again, and the strength may be reduced, or in an extreme case, expansion crack may occur. Therefore, in order to improve the sulfate resistance,
It is necessary to reduce the amount of aluminate phase.

On the other hand, when gypsum is present, the ferrite phase produces hydrates such as ettringite as in the aluminate phase. However, the reaction rate is slower and the heat of hydration is lower than that of the aluminate phase. The ferrite phase is
In order to generate ettringite, it is said that CaO is slightly insufficient, so that it hardly becomes ettringite, and that even if it becomes ettringite, it does not cause so much expansion.

However, as mentioned above, the ferrite phase is
It is known that it has excellent sulfate resistance, but its strength development is low, so that it is not actively used. The iron cement according to the above-mentioned Japanese Patent Laid-Open No. 50-10314 contains about 20% of the ferrite phase due to the converter slag which is one of the main raw materials, but it is for the purpose of resource saving and energy saving. The amount of alite is increased in order to improve the strength, and the heat of hydration tends to be high.

Further, the increased ferrite phase is replaced with belite and almost no belite is contained, so that the elongation of long-term strength tends to be small. Further, this cement having a high ferrite phase tends to exhibit a color different from the grayish green color of ordinary Portland cement, so that there is a problem that it is difficult to be accepted in the market.

The present invention has been made to solve the above problems, and uses a hydraulic admixture having excellent strength development, low heat buildup, sulfate resistance, etc., a method for producing the same, and a hydraulic admixture for the same. The purpose is to provide mixed cement that has been used.

[0017]

In order to achieve the above object, the first aspect of the present invention is that the ferrite phase is 30 to 50 w.
t-% and β-dicalcium silicate 15-45w
t%, calcium fluoroaluminate 1 to 5 wt%,
This is a hydraulic mixture material containing a high ferrite phase and containing 2 to 10 wt% of fluorapatite and an unavoidable component.

A second aspect of the present invention is a ferrite phase obtained by adding lime source, alumina source and iron oxide source to slag powder generated by dephosphorizing pig iron, followed by firing, and containing 30 to 50 wt% of ferrite phase. It is a high content hydraulically admixture material.

A third aspect of the present invention uses slag powder generated by dephosphorizing pig iron, a lime source and an alumina source, Fe ₂ O ₃ /
An iron oxide source was added and blended so that (CaO + Al ₂ O ₃ ) ≦ 1/5 (mol / mol), and then 1000
The method is for producing a hydraulically admixture having a high ferrite phase content, which is characterized by being fired at ˜1200 ° C. for 60 to 150 minutes.

A fourth aspect of the present invention is a hydraulic admixture having a high ferrite phase content, which is obtained by mixing 10 to 30 wt% of the hydraulic admixture of the first, second or third aspect of the invention with a cement raw material. This is the mixed cement used.

In the first invention, the content of the ferrite phase is 3
It is necessary to be 0 to 50 wt%. If it is less than 30%, the sulfate resistance of the ferrite phase cannot be sufficiently exhibited. On the other hand, when it exceeds 50%, the amount of β-dicalcium silicate, calcium fluoroaluminate, fluoroapatite, etc. decreases, resulting in low heat of hydration,
It will not be possible to fully exhibit the characteristics such as improvement in initial strength.

The β-dicalcium silicate has a low initial strength development property, but is characterized by low heat of hydration and high long-term strength development property. If the content is less than 15 wt%, it is difficult to satisfy the long-term strength development. The higher the upper limit, the more effective it is, but it was set to 45 wt% based on the ratio with other mineral components.

Calcium fluoroaluminate is a quick-hardening mineral and is known as a mineral contained in jet cement. If the content is less than 1 wt%, the initial strength development is lowered, which is not desirable. The higher the upper limit, the more effective it is, but it is 5 wt% from the ratio with other mineral components.
And

Fluorapatite has a low strength developing property, but the fluorine (F) portion in its structure is C.
By partially substituting with O ₃ ²⁻ , Cl ^−, etc., there is a possibility that carbonation (neutralization), which is a problem in reinforced concrete, and salt damage to marine concrete can be suppressed. When the content deviates from 2 to 10 wt%, it is difficult to suppress carbonation (neutralization) in reinforced concrete and salt damage to marine concrete as described above.

In the second invention, the components of β-dicalcium silicate, calcium fluoroaluminate, and fluoroapatite described above are obtained from slag powder generated by dephosphorizing pig iron, and the ferrite phase component is added to the slag. , A lime source, an alumina source, and an iron oxide source were added and fired.

The chemical composition of the slag powder generated by dephosphorizing pig iron is approximately 40 to 60 wt% CaO and S.
_{iO 2: 10~20wt%, Al 2} O 3: 0.5~ 4
wt%, MgO: 0.5-4 wt%, F: 1-4 w
t%, P: 1 to 3 wt%, T · Fe: 5 to 20 wt
%, In the range. Here, the metallic iron contained in the slag has been removed by magnetic separation or the like and can be stably obtained.

By utilizing the slag powder, an inexpensive hydraulic admixture can be obtained. In the third invention, Fe ₂ O ₃ / (CaO + A) is added to the slag powder, the lime source, and the alumina source.
It is necessary to add and formulate an iron oxide source so that 1 ₂ O ₃ ) ≤ 1/5 (mol / mol).

Here, the ferrite phase, that is, 4CaO.Al
The theoretical molar ratio required to produce a ₂ O ₃ · Fe ₂ O ₃ to allow minimally maintained, formulated by adding an iron oxide source.
Lime source and iron oxide source are free C contained in slag powder.
It is added in consideration of aO and iron components.

The above formulation is calcined at 1000-1200 ° C. If it is less than 1000 ° C, the ferrite phase is not sufficiently formed. On the other hand, when the temperature exceeds 1200 ° C, the production of ferrite phase increases, but calcium fluoroaluminate or the like may be decomposed, which is not preferable.

When the firing time is less than 60 minutes, the ferrite phase is not sufficiently formed, and when it exceeds 150 minutes, it does not increase so much. Therefore, the firing time is set to 60 to 150 minutes. After firing and cooling, the fired product is pulverized to obtain the hydraulic admixture material of the present invention. The degree of pulverization is from 2000 to 2000 in terms of Blaine specific surface area.
A range of 5000 cm ² / g is suitable. 2000 cm ² /
If it is less than g, the hydration reactivity becomes small and it is not practical. If it exceeds 5000 cm ² / g, the crushing requires a high cost.

According to the above manufacturing method, the ferrite phase is 3
0 to 50 wt% and 1 of β-dicalcium silicate
5-45 wt%, calcium fluoroaluminate 1-
It is possible to obtain a hydraulic admixture material having a high ferrite phase content of 5 wt%, fluoroapatite 2 to 10 wt% and an unavoidable component.

The hydraulic admixture material of the present invention is usually added to a commercially available cement such as Portland cement, that is, used as an admixture material. The cement to be added is usually ordinary Portland cement, but may be other Portland cement, or mixed cement such as blast furnace / fly ash / silica cement.

The addition rate varies depending on the type of cement, but is 10 to 30 wt% in the present invention. If it is less than 10 wt%, the properties of low heat of hydration and sulfate resistance cannot be sufficiently exhibited, and if it exceeds 30 wt%, the initial strength is lowered, which is not preferable.

As described above, the hydraulic admixture manufactured according to the present invention contributes to the improvement of sulfate resistance by containing the ferrite phase, and at the same time, the β-dicalcium silicate contained in the slag as the main raw material is contained. Reduction of hydration heat,
Calcium fluoroaluminate contributes to the improvement of initial strength for the improvement of long-term strength. Fluorapatite contained in the slag also contributes to suppressing deterioration of concrete due to carbonation and salt damage.

[0035]

EXAMPLES Experimental examples of the present invention will be described below. (Experimental Example 1) As the slag, one produced in the process of removing phosphorus (P) in pig iron by using a flux of quicklime, fluorite or the like in pig iron in the iron making process was used. The slag was first crushed to 5 mm or less with a jaw crusher, and separated into magnetic and non-magnetic substances with a magnet. Then, the non-magnetized material was further crushed and magnetically separated by a ball mill to obtain a slag sample of 0.1 mm or less. The chemical components of this slag are shown in Table 1, and the powder X-ray diffraction results are shown in FIG.

[0036]

[Table 1]

From FIG. 1, it can be seen that the slag contains β-dicalcium silicate, calcium fluoroaluminate, fluoroapatite and the like. The blending of the hydraulically admixture material with a high ferrite phase content is based on the goal of 50 wt% ferrite phase content, 100 wt% slag, and reagent C.
ACO ₃ 63 wt%, reagent Al ₂ O ₃ 18wt%, was plus reagent Fe ₂ O ₃ 16wt%.

Each sample, which was weighed a predetermined amount, was wet-mixed with methanol in an automatic mortar. The mixed sample was put into an alumina crucible and baked in an electric furnace at a predetermined temperature for a predetermined time. After the fired product was cooled, it was pulverized and a 200 mesh (74 μm) pass was used as a sample for various measurements.

First, in order to obtain the relationship between the firing temperature and the amount of ferrite phase produced, the firing time was kept constant at 120 minutes, and
900, 950, 1000, 1050, 1100, 11
Samples were prepared at temperatures of 50, 1200 and 1250 ° C, respectively. Powder X-ray diffraction was performed in order to examine the amount of ferrite phase produced in the produced sample. The amount of ferrite phase generated is (020) plane [2θ = 11.99] of the ferrite phase.
Degree, d = 7.39 angstrom].

The results are shown in FIG. 2 to 900-10
In the range of 50 ° C, the peak intensity increases with temperature,
It is clear that the range of 050 to 1150 ° C. is flat and further improves at 1200 ° C. or higher. In order to increase the ferrite phase, it is desirable that the firing temperature is higher, but the reason why the temperature exceeds 1200 ° C is considered to be due to the decomposition of calcium fluoroaluminate, and the original properties of the slag deteriorate. Is not preferable. Therefore,
The firing temperature is preferably in the range of 1000 to 1200 ° C.

(Experimental Example 2) In order to obtain the relationship between the firing time and the amount of ferrite phase produced, the firing temperature was kept constant at 1150 ° C. and the firing time was 30, 60, 90, 120, 18
A sample was prepared in the same manner as in Experimental Example 1 except that the time was 0 or 240 minutes. In order to investigate the amount of ferrite phase produced in the produced sample, powder X-ray diffraction was performed in the same manner as in Experimental Example 1. The results are shown in Fig. 3. From FIG. 3, it is clear that the amount of ferrite phase produced does not change after 60 minutes. Therefore, 60 minutes is sufficient for the firing time, but 60 to 150 minutes is a preferable range in consideration of fluctuations in actual production.

(Experimental Example 3) In order to investigate the strength development of the hydraulically admixable material according to the present invention, the compressive strength was measured. The sample was prepared according to the composition of Experimental Example 1, and the firing temperature was 10
The temperature was 50 ° C. and the firing time was 120 minutes. After firing, as in Experimental Example 1, a sample was crushed to 200 mesh or less. The powder X-ray diffraction pattern of the prepared sample is shown in FIG. From FIG. 4, this sample has a high content of the ferrite phase indicated by ●, β-dicalcium silicate indicated by ▲, calcium fluoroaluminate indicated by ■, ◆.
It is clear that it contains the fluorapatite indicated by the mark.

Next, 10, 20, 30 wt% of this sample was added to a commercially available ordinary Portland cement and mixed sufficiently. The hydraulic admixture material of the present invention had a fairly dark color, but when added to ordinary Portland cement, no visual difference was observed with ordinary Portland cement.

The compressive strength was measured using four types of plain Portland cement alone and plain Portland cement with the hydraulic admixture of the present invention added at 10, 20 and 30 wt%. To prepare the test body, 25 wt% of water (water cement ratio: 25%) was added to 100 wt% of this sample, and the mixture was sufficiently kneaded and then put into a 4 × 4 × 16 cm mold and molded. This was aged at 20 ° C. and a relative humidity of 95% or more for 24 hours, demolded from the mold, and further aged for a predetermined time under the same conditions. The age of measuring the compressive strength was 7 days and 28 days.

The results are shown in FIG. The mark ● indicates the case of ordinary Portland cement alone, the mark ▲ indicates the addition rate of 10 wt%, the ■ mark indicates the addition rate of 20 wt%, and the ◆ mark indicates the case of the addition rate of 30 wt%. From FIG. 5, the 7-day strength decreases as the addition rate of the hydraulic admixture of the present invention increases. However, regarding the 28-day strength, when the addition rate of 10 wt% exceeds the ordinary Portland cement strength, the addition rate of 20 wt% is equivalent. When the addition rate is 30 wt%, the 28-day strength is low, but the elongation from 7 to 28 days exceeds the ordinary Portland cement strength, and it can be expected to be equivalent to that when it is cured for a long time.

Experimental Example 4 The heat of hydration was measured for the hydraulically admixture material of the present invention. The samples to be measured were four types of commercially available ordinary Portland cement alone and ordinary Portland cement used in Experimental Example 3, and the hydraulic admixture of the present invention was added at 10, 20, and 30 wt%. The heat of hydration was obtained by doubling the weight ratio of water to these samples (cement ratio: 2
(00%) was measured with a conduction calorimeter manufactured by Tokyo Riko. The measurement time was 24 hours.
The results are shown in FIG.

Further, the heat generation rate per unit time was calculated from the heat generation area of the hydration heat generation rate curve of FIG. The results are shown in Table 2. From these results, it is clear that the addition of the hydraulically admixture material of the present invention significantly reduces the initial hydration heat generation rate. Also, due to the increase in the addition rate,
The hydration heat generation rate is increasing.

This is because the calcium fluoroaluminate contained in the hydraulic admixture of the present invention increased the hydration heat generation rate at the very initial stage. The decrease at 30 wt% is again observed because the hydration of the whole sample is delayed due to the increase of β-dicalcium silicate.
All of the materials to which the hydraulic admixture of the present invention is added are characterized in that the secondary peak due to conversion to conventional monosulfate is significantly reduced.

[0049]

[Table 2]

The ferrite phase was replaced with the reagents CaCO ₃ and A.
In the case of synthesizing only 1 ₂ O ₃ and Fe ₂ O ₃ , the firing temperature is 1
A temperature of 300 ° C or higher is required. However, Experimental Example 1 of the present invention
As can be seen from ~ 3, it is possible to synthesize even at about 1000 ° C. Therefore, it is possible that the slag affects the decomposition temperature of CaCO ₃ and the formation of the ferrite phase.

Therefore, for the sample containing the reagent CaCO ₃ and slag added thereto in an amount of 10, 20, and 30 wt%,
The decomposition temperature of CaCO ₃ was measured. A differential thermal analyzer manufactured by Rigaku Denki was used for the measurement.

The results are shown in FIG. It can be seen from FIG. 7 that the decomposition temperature of CaCO ₃ is lowered by the addition of slag. The reason why the ferrite phase can be generated at low temperature is Ca
Although it cannot be explained only by the decomposition temperature of CO ₃ , phosphorus (P), fluorine (F), etc. in the slag act catalytically,
It is presumed that low temperature generation of the ferrite phase is achieved.

[0053]

As described above, according to the present invention, a hydraulic admixture having excellent strength development, low heat build-up, sulfate resistance and the like can be satisfied at the same time, and the versatility of hydraulic properties is high. It is an admixture. Moreover, there are the following effects. (1) Slag that has not been effectively utilized can be effectively utilized as a hydraulic admixture material. (2) Since the mixed cement containing a predetermined amount of the hydraulic admixture has a high ferrite phase content, it has excellent sulfate resistance and is particularly suitable as a marine cement.

(3) It has low heat buildup and is suitable as a cement for mass concrete which requires low heat buildup in order to prevent temperature cracking. (4) The CaO content of slag can be used, limestone resources can be saved during cement production, and CO ₂ gas emissions can be reduced. (5) It is an energy-saving material because it can be fired at a low temperature.

As described above, the hydraulic admixture produced by the method of the present invention and the mixed cement containing the same are excellent from the viewpoints of resource saving, energy saving and improvement of the global environment, and their industrial value is great. .

[Brief description of drawings]

FIG. 1 is a view showing a powder X-ray diffraction pattern of slag used in the present invention.

FIG. 2 is a diagram showing the relationship between the firing temperature and the amount of ferrite phase produced according to the present invention.

FIG. 3 is a diagram showing the relationship between the firing time and the amount of ferrite phase produced according to the present invention.

FIG. 4 is a diagram showing an experimental example of a powder X-ray diffraction pattern of the hydraulically admixture material obtained by the present invention.

FIG. 5 is a view showing the results of compressive strength test when the hydraulic admixture obtained according to the present invention is added to ordinary Portland cement.

FIG. 6 is a diagram showing a hydration heat generation rate curve when the hydraulic admixture obtained according to the present invention is added to ordinary Portland cement.

FIG. 7 is a diagram showing a differential thermal analysis result of a sample in which slag is added to the reagent CaCO ₃ .

Front page continuation (72) Inventor Naoki Tsurugi 6-2035 Kanesugi, Funabashi City, Chiba Prefecture (72) Masaki Kanai 3-23 Nosato, Minato-ku, Nagoya City, Aichi Prefecture

Claims (4)

[Claims] 1. A ferrite phase of 30 to 50 wt%, β
-A hydraulic mixture material having a high ferrite phase and containing 15 to 45 wt% dicalcium silicate, 1 to 5 wt% calcium fluoroaluminate, 2 to 10 wt% fluoroapatite, and an unavoidable component. 2. A ferrite phase high content water obtained by adding 30% to 50% by weight of a ferrite phase to a slag powder generated by dephosphorizing pig iron, adding a lime source, an alumina source and an iron oxide source and firing the mixture. Hard admixture. 3. Fe ₂ O ₃ / (CaO + A) is added to the slag powder, lime source, and alumina source generated by dephosphorizing pig iron.
l ₂ O ₃ ) ≦ 1/5 (mol / mol), iron oxide source is added and blended, and then 1000 to 1200 ° C.
A method for producing a hydraulically admixture having a high ferrite phase content, characterized by being baked for 60 to 150 minutes. 4. A cement material containing 10 to 10 of the hydraulically admixable material having a high ferrite phase content according to claim 1 or 2 or the hydraulically admixable material having a high ferrite phase produced by the production method according to claim 3. A mixed cement containing 30 wt%.