JP4616113B2 - Quick-hardening clinker and cement composition - Google Patents

Description

  The present invention relates to a rapid clinker and a cement composition using the clinker, and in particular, exhibits rapid hardening and can reduce the content of hexavalent chromium, which is a harmful heavy metal, and the rapid clinker and the clinker. The present invention relates to a cement composition using a clinker.

In recent years, in construction work for tunnels and underground spaces, a spraying construction method has been widely practiced in which a cement mixture such as mortar and concrete is sprayed and lined on a wall surface or an exposed surface to prevent collapse of the wall surface or the exposed surface.
In this concrete spraying method, concrete is prepared, and the minimum usable time (handling time) necessary for handling it is secured, and after spraying on the wall surface or exposed surface, the concrete is immediately cured. It is necessary to let
In addition, it is necessary to secure the pot life of mortar and concrete in water stoppage work and emergency work and to harden it immediately.

Conventionally, as a clinker used for a rapid-hardening cement, there are a jet cement clinker, an Irwin clinker whose main component is C ₄ A ₃ SO ₃ , an alumina cement clinker whose main component is CA, and the like.
There is also a method of obtaining amorphous C ₁₂ A ₇ by melting a clinker mainly composed of C ₁₂ A ₇ which is a rapid hardening component and then rapidly cooling it.

However, the conventional jet cement clinker is a clinker containing a calcium silicate phase as a main component and containing about 20 to 30% by weight of C ₁₁ A ₇ · CaF ₂ as a fast-hardening component, and is a rapid hardening component of C ₁₂ A ₇ . It is not satisfactory as a clinker for a rapid hardening cement because it has a low content and cannot exhibit sufficient rapid hardening.
Irwin-based clinker is used as a clinker for quick-hardening cement because it contains 70% by weight or more of erwin (C ₄ A ₃ SO ₃ ) having quick-hardening properties. There is a problem that it is inferior in rapid hardening at low temperatures.

Alumina cement clinker composed mainly of CA, compared to clinker mainly composed of C ₁₂ A _7, is inferior suddenly rigid, the clinker mainly composed of conventional C ₁₂ A _7, for example, the aforementioned The clinker based on C ₁₂ A ₇ which is a rapid hardening component is once melted and then rapidly cooled to synthesize amorphous C ₁₂ A ₇ . The method of manufacturing a clinker is complicated. In this manufacturing method, since the electrofusion method is used for melting the clinker, a large amount of power is consumed, the power cost is increased, and the manufacturing cost is eventually increased. is there.

  There is also a quick-setting cement that adds quick setting material to Portland cement to give rapid hardening, but usually a large amount of quick setting material such as calcium aluminate or Irwin is added to Portland cement. For this reason, in addition to an increase in cost, there is a disadvantage in that a high quick setting property cannot be obtained and a problem arises in strength.

In Japanese Patent Laid-Open No. 2002-293594, a predetermined hard working time can be secured, and as a hardened cement composition and a quick setting material that harden rapidly after the working time has passed, it has a certain range of lattice constants. A sintered body containing a crystalline C ₁₁ A ₇ · CF ₂ solid solution is blended, and preferably 40% by weight or more, a rapid setting material for rapid hardening cement, and the rapid setting material is fixed to the base cement. A hardened cement composition with added content is disclosed.

Japanese Patent Application Laid-Open No. 2003-267762 discloses calcium aluminate, sulfate, sodium aluminate having a molar ratio of NaO ₂ / Al ₂ O ₃ of less than 1.0, and Portland cement as a rapid setting material for concrete. A rapid setting material to be contained, wherein the amount of Na ₂ O in the quick setting material is 1.5 to 10.0% by mass, and the total amount of calcium aluminate, sulfate and sodium aluminate is 100 parts by mass. On the other hand, a quick setting material in which the amount of Portland cement is 1.0 part by mass or more is disclosed.

  However, both of these conventional quick setting materials and quick setting cements require special raw materials and equipment to obtain the quick setting materials, which makes the manufacturing complicated and increases the manufacturing cost. In addition, a cement composition in which a quick setting material is added to Portland cement has a problem that it is difficult to express a quick setting performance as expected.

On the other hand, in recent years, for the purpose of reducing hexavalent chromium in cement, baking in a cement reducing atmosphere has also been studied, and Japanese Patent Application Laid-Open No. 2002-249775 discloses that it is manufactured in a reducing atmosphere at 1000 ° C. or higher. In addition, a fast-hardening type solidifying material is disclosed that includes calcium aluminate, cement, lime, and gypsum and reduces the elution of hexavalent chromium by the action of calcium aluminate.
Japanese Patent Application Laid-Open No. 2004-18339 discloses a method for reducing hexavalent chromium in a cement clinker in which a cement clinker containing hexavalent chromium is heat-treated at 650 to 1100 ° C. in a reducing atmosphere.

However, these methods have a problem in that although the amount of hexavalent chromium is reduced, C ₃ S is decomposed and hydration activity is reduced, resulting in a decrease in strength.
JP 2002-293594 A JP 2003-267762 A JP 2002-249775 A JP 2004-18339 A

Accordingly, an object of the present invention is to provide a quick-cure clinker that is easy to manufacture, does not require special equipment and equipment, has excellent hydration activity, has good quenching performance, and is economically inexpensive. It is.
Another object of the present invention is to provide an economically inexpensive cement composition that can secure a predetermined pot life using the rapid-hardening clinker and exhibits excellent quick-hardness.

In the present invention, C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) is calcined in a reducing atmosphere to obtain C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen). This is achieved by finding that the amount of substitutional solid solution from Al ³⁺ to Fe ³⁺ in the solid solution can be reduced, the hydration activity can be improved, and the rapid hardening action can be expressed.

That is, the rapid clinker of the present invention has a content of C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) before firing in a reducing atmosphere, and is 20 to 30% by mass, The C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) is baked at 1300 to 1380 ° C. in a reducing atmosphere , and the lattice constant measured by X-ray diffraction is 11.93 to it characterized in that it is a 11.96Å.
The rapid-hardening cement composition of the present invention includes the rapid-hardening clinker of the present invention and a sulfate.
Preferably, the cement composition of the present invention contains 70 to 90% by mass of the rapid-hardening clinker and 10 to 30% by mass of sulfate.

The quick-hardening clinker of the present invention does not require special equipment or equipment, is easy to manufacture, has excellent quick-hardening performance by improving hydration activity, and reduces the content of hexavalent chromium, which is a hazardous heavy metal Economically and inexpensively.
In addition, the cement composition of the present invention can ensure a predetermined pot life, exhibits excellent rapid hardening performance by improving hydration activity, and reduces the content of hexavalent chromium which is a harmful heavy metal, It becomes possible to make it economically cheap.
Therefore, the present invention can be effectively applied to rapid hardening applications at work sites and the like, and it is possible to greatly improve problems such as water contamination and soil contamination due to hexavalent chromium contained in cement.

The present invention is illustrated by the following preferred examples, but is not limited thereto.
The rapid hardening clinker of the present invention will be described.
The rapid-hardening clinker of the present invention is obtained by firing C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) in a reducing atmosphere, preferably at 1300 to 1380 ° C. .
In this way, by firing C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ in a reducing atmosphere, Al ³⁺ in C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ is substituted with Fe ³⁺ . A rapid hardening clinker that can reduce the amount of solution, improve hydration activity, develop a rapid hardening action, is relatively inexpensive, does not require special equipment, and has a low hexavalent chromium content, and the clinker Thus, a quick-hardening cement composition can be obtained.

First, calcium aluminate of C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents a halogen) is based on, for example, the Bogue formula, calcareous raw material (eg, quick lime, slaked lime, limestone), alumina raw material (eg; (Aluminum hydroxide, alumina) and calcium fluoride raw material (eg, fluorite) are blended as necessary.
Next, the blended raw material is calcined in a reducing atmosphere to obtain a clinker. The calcining temperature varies depending on the raw material, the calcining method, etc., and cannot be determined in general, but C ₁₂ A ₇ or C ₁₁ A _7. Clinker is obtained by firing at a temperature lower than the melt temperature of the CaX ₂ (X represents halogen) solid solution, for example, at a temperature of 1300 to 1380 ° C., preferably 1330 to 1370 ° C.
For example, when the firing temperature is less than 1300 ° C., firing becomes insufficient, and when it exceeds 1380 ° C., decomposition of C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ occurs.
The firing time cannot be generally determined by the amount of clinker to be treated, but is usually about 1 to 2 hours.

  The atmosphere at this time is a reducing atmosphere, but the reducing atmosphere is not particularly limited. Usually, reducing properties such as carbon monoxide and hydrogen are suppressed in a state where oxygen supply is suppressed in a sealed container. Use a reducing atmosphere by a method of heating while supplying gas, a method of heating to supply flammable materials such as various solid fuels and flammable waste in a sealed container with oxygen supply suppressed. In particular, a method of supplying a reducing gas is preferable from the viewpoint of preventing a change in the quality of the clinker due to residual combustion products.

The reducing gas may be supplied directly to the portion to be fired, or may be supplied after being diluted with an inert gas such as argon. The degree of dilution is not particularly limited, and usually the reducing gas is used. It is sufficient if the concentration is at least about 1% by volume or more.
When supplying the reducing gas, it is preferable to completely shut off the supply of oxygen.

At this time, when C ₁₂ A ₇ or C ₁₁ A ₇ .CaX ₂ (X represents halogen) is produced in the course of firing in a reducing atmosphere, the rapid hardening clinker of the present invention is produced.
Note that a clinker containing C ₁₂ A ₇ or C ₁₁ A ₇ .CaX ₂ (X represents halogen) produced separately may be reduced and fired instead of the above-described blended raw materials. For example, a cement cooler The clinker in a heated state taken out from an appropriate path may be the target of processing, and the clinker that has been cooled after firing may be the target of processing, and a normal lump clinker can be processed in the same size. .

_Thus, the _C 12 _{A 7} or _{C 11 A 7 · CaX 2 (} X is a halogen) containing clinker by firing in a reducing atmosphere, _{typically, C 11 A 7 · CaX 2 (} X is a halogen 8-9 mass% of Fe ³⁺ is substituted and dissolved in Al ³⁺ in (shown), but since Fe ³⁺ is reduced to Fe ²⁺ , the amount of Fe ³⁺ is reduced by hydration. The activity is improved and good rapid hardening can be exhibited.
Moreover, since Cr ⁶⁺ is reduced to Cr ³⁺ , the effect that hexavalent chromium contained can be reduced can also be expected.

Such C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) -containing clinker includes C ₁₂ A ₇ , C ₁₁ A ₇ · CaX ₂ (X represents halogen) in addition to C ₃ A. ), C ₃ S, C ₂ S, C ₄ AF, or the like.
Preferably, during the _C 12 _{A 7} or _{C 11 A 7 · CaX 2 (} X is a halogen) containing _{clinker, C} 12 _{A 7} or _{C 11 A 7 · CaX 2 (} X is a halogen) is , Ru contains 20 to 30 wt%.
If it is 20% by mass or more, sufficient rapid hardening and strength development can be obtained, and if it is 30% by mass or less, it is possible to produce a clinker while maintaining good properties without being excessively melted. .

The C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) -containing clinker after firing in a reducing atmosphere has a lattice constant measured by X-ray diffraction of 11.93 to 11.96Å.
By different lattice constants, the setting speed, that is, the degree of rapid hardening, is different, so in order to secure the pot life and obtain rapid hardening, the range of lattices can be obtained by firing at the above firing temperature. It would be desirable to obtain a constant number of hard clinker.
If the lattice constant is within this range, the properties of the resulting rapid-hardening clinker will not vary, and the setting time can be easily and accurately controlled, ensuring the specified handling time and obtaining rapid hardening. Is possible.
However, the lattice constant is a value measured by powder X-ray diffraction. The metal silicon powder manufactured by High Purity Chemical Laboratory is used as an internal standard, and X-Pert Pro system manufactured by Spectris Co. is used for powder X-ray diffraction. The measurement conditions will be described in detail in the following examples.

The rapid hardening clinker, which is the C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) -containing clinker, is pulverized and used as a powder in a cement composition.
The clinker preferably has a brain specific surface area of 4500 cm ² / g or more, and if it is less than 4500 cm ² / g, good rapid hardening may not be obtained.
Further, the larger the specific surface area of the brain, the longer the pulverization time is required, the lower the productivity and the higher the cost, so 5000-7000 cm ² / g is desirable.
Further, a grinding aid (diethylene glycol, triethanolamine, etc.) may be added when grinding.

The quick-hardening cement composition of the present invention is a rapid-hardening clinker powder of the present invention, which is a clinker powder containing C ₁₂ A ₇ or C ₁₁ A ₇ .CaX ₂ (X represents halogen) fired in the reducing atmosphere. It contains a sulfate.
The sulfate functions as a setting regulator.
Specific examples include alkali metal sulfates such as sodium sulfate (sodium sulfate) and potassium sulfate, alkaline earth metal sulfates such as magnesium sulfate and gypsum (calcium sulfate), and aluminum sulfate. Or the combined use of gypsum and mirabilite.
Examples of the gypsum include anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, or a mixture thereof.
Moreover, slaked lime is mentioned as a material which can be mix | blended as needed. The slaked lime is added for strength enhancement.

The fineness of these sulfates and slaked lime is not particularly limited, but is preferably 3000 cm ² / g or more.
In view of strength development and cost, a fineness of 4000 to 10000 cm ² / g is more preferable.

C ₁₂ A ₇ or C _{11 A 7} · _CaX 2 produced in a reducing atmosphere is steeper rigid clinker powder of the present invention of the present invention _(X is a halogen) clinker powder is added as needed also sulfates, The ratios of slaked lime are 70 to 90% by mass, 10 to 30% by mass, and 0 to 1% by mass, respectively.
From the standpoint of ensuring rapid hardening and handling time, 79 to 84% by mass of C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) clinker powder after firing in the above reducing atmosphere, and 15 to 15% of sulfate. It is desirable that -20 mass% and slaked lime are 0-1 mass%.

In the above ratio, when the C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) powder is less than 70% by mass, the rapid hardening becomes small, and when it exceeds 90% by mass, the solidification occurs and the handling time is short. Cannot be ensured, both of which are undesirable.
On the other hand, if the sulfate content is less than 10% by mass, it is difficult to secure a handling time due to instantaneous setting.

The mixing method of the C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents a halogen) clinker powder, sulfate, and slaked lime is not particularly limited, and after blending in a ratio within the above numerical range. What is necessary is just to mix using a conventional mixing apparatus.

  In addition, the cement composition of the present invention includes a set retarder (lignin sulfonic acid, oxycarboxylic acid, various organic acids such as saccharides, alkali metal salts or alkaline earth metal salts of organic acids) and water reducing agents. (Alkyl allyl sulfonic acid type, naphthalene sulfonic acid type, melamine sulfonic acid type, polycarboxylic acid type, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent are also included), etc. Fine aggregates (river sand, sea sand, mountain sand, crushed sand and mixtures thereof), coarse aggregates (river gravel, sea gravel, crushed stones and mixtures thereof) and the like can be blended.

Mortar and concrete can be produced by blending water into the cement composition using these raw materials, and the method for producing these mortar and concrete is not particularly limited, and the raw material is obtained using a conventional mixer. Mix it.
These mortars and concretes can be applied to, for example, a wet spraying method, and a conventional apparatus can be used as it is as a spraying apparatus.

The present invention will be described based on the following examples and test examples.
Test example
1) Clinker raw materials were prepared by blending reagents so that the clinker chemical composition after firing and firing was as shown in Table 1.
The theoretical clinker mineral composition obtained by the Borg method based on the chemical composition of Table 1 is as shown in Table 2.

The clinker raw material was baked in an electric furnace at each temperature shown in Table 7 for 1 hour in the air, then taken out from the electric furnace and rapidly cooled in the air to obtain an oxidized baked clinker.
As for the reduced fired product, a clinker raw material and activated carbon were placed in a crucible, and fired at a temperature shown in Table 7 for 1 hour in a reducing atmosphere to obtain a reduced fired clinker.

2) Analysis of mineral composition Each clinker obtained was diffracted using an X-ray diffraction apparatus (manufactured by Rigaku Corporation; RAD-rC), and the mineral composition was as theoretical.

3) Measurement of clinker lattice constant The clinker lattice constant obtained was measured as follows, and the results are shown in Table 3 and FIG.
Metallic silicon powder manufactured by High-Purity Chemical Laboratory is used as an internal standard, and X'Pert Pro system manufactured by Spectris is used. Measured by powder X-ray diffraction.
i) Measurement conditions-Tube: Cu
-X-ray monochromatic color: Counter monochromator-Tube voltage: 45kV
・ Tube current: 40 mA
・ Measurement mode: Step scan ・ Step width: 0.0167 °
・ Counting time: 1 second ・ Slit: SS 1 mm
: DS 1mm
: RS 0.15mm
-Scanning range (2θ): 5-60 °
ii) Calculation of lattice constant The diffraction angle was read by the half-width midpoint method, and the diffraction angle was corrected by calculating the correction value from the diffraction line of the obtained internal standard sample and by the least square method.

4) Elemental analysis of clinker by EPMA Each clinker obtained was roughly crushed to 2 to 3 mm, embedded in resin, mirror-polished and subjected to carbon deposition, and JXA-8621 type X-ray microanalyzer analysis made by JEOL Ltd. Elemental analysis (Al2O3 and Fe2O3) was measured as follows using the apparatus, and the results are shown in Table 4 and FIG.
Measurement conditions ・ Acceleration voltage: 15.0 KV
・ Irradiation current: 30 nA
・ Probe diameter: 1μm
・ Quantitative correction calculation method: Oxide / ZAF method

5) Preparation of cement composition Next, 100 parts by mass of each clinker was coarsely pulverized, 1 part by mass of mirabilite (sodium sulfate) was mixed with each clinker, and 0.08 parts by mass of pulverization aid (diethylene glycol) was added. It was used and pulverized until the specific surface area of the brain was about 5200 ± 100 cm ² / g to obtain each clinker powder.
The clinker powder, anhydrous gypsum (trade name; non-clave, manufactured by Sumitomo Osaka Cement Co., Ltd.), hemihydrate gypsum (trade name; baked gypsum, manufactured by Wako Pure Chemical Industries, Ltd.) and slaked lime (Wako Pure Chemical Industries, Ltd.) Were mixed at a ratio shown in Table 5 so that the molar ratio of SiO ₂ / Al ₂ O ₃ was 1.2 and mixed uniformly to prepare each cement composition.

6) Preparation of mortar Each of the above cement compositions, sand (Toyoura standard sand), setting agent (reagent; citric acid, manufactured by Wako Pure Chemical Industries, Ltd.), water and admixture (manufactured by Kao Corporation, product) Name: Mighty 150) was blended in the proportions shown in Table 6 and kneaded uniformly to obtain a mortar.

7) Handling time and milling temperature test The handling time of each mortar obtained above was measured.
For each handling time, a cone cone (350 g) having a diameter of 1 cm and a height of 2 cm was attached instead of the bigger needle of the condensation test method of JIS R5201-1997, and the time until the penetration degree was 1.5 mm was defined as the handling time.
The kneading temperature is a value obtained by measuring the temperature immediately after kneading after adding each material and water to obtain the mortar.
The results are shown in Table 7.

From Table 7, Examples 1-2 have higher refining temperatures and shorter handling times than Comparative Examples 1-2.
From this, it can be seen that Examples 1 and 2 have high rapid hardening performance.

  The quick-hardening clinker and the quick-hardening cement composition using the clinker according to the present invention include tunnels and underground space construction work, civil engineering work, water stoppage work, spraying work on wall surfaces, repair work for emergency roads, etc. In addition, as a soil improvement material, while ensuring a predetermined handling time, it is possible to control water pollution and soil contamination, etc. It can be usefully applied to the required work location.

Graph showing the relationship between the firing temperature and the C _{11 A} 7 _· CaF ₂ lattice constant of clinker in an oxidizing atmosphere or a reducing atmosphere. Diagram showing the clinker calcination in an oxidizing atmosphere or a reducing _atmosphere, the relationship between the _Al 2 _{O 3} content and _Fe 2 _{O 3} content of C ₁₁ A 7 · CaF _2.

Claims (3)

The content of C ₁₂ A ₇ or C ₁₁ A ₇ · CaX ₂ (X represents halogen) before firing in a reducing atmosphere is 20 to 30% by mass, and the C ₁₂ A ₇ or C ₁₁ A ₇ CaX ₂ (X represents halogen) is fired in a reducing atmosphere at 1300 to 1380 ° C. , and the lattice constant measured by X-ray diffraction is 11.93 to 11.96 Å A quick-hardening clinker. A sudden hard clinker according to claim 1 Symbol mounting, characterized in that it comprises a sulfate salt, rapid hardening cement composition. The cement composition according to claim 2, wherein the cement composition contains 70 to 90% by mass of a rapid hardening clinker and 10 to 30% by mass of a sulfate.

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