JP7044996B2 - Hard additive for cement and its manufacturing method - Google Patents

Description

The present invention relates to a hard-hardening additive for cement and a method for producing the same, and in particular, when added to any cement, imparts good initial strength to the cement not only at room temperature but also at high temperatures such as summer. The present invention relates to a hard-hardening additive for cement and a method for producing the same, which can sufficiently secure a predetermined fluidity and is excellent in workability.

In recent years, in the construction work of tunnels and underground spaces, a spraying method of spraying a cement mixture such as mortar or concrete onto a wall surface or an exposed surface to lining the wall surface or the exposed surface to prevent the wall surface or the exposed surface from collapsing has been widely implemented.
In such a concrete spraying method, concrete, etc. is prepared, the minimum usable time (handling time) required for handling it is secured, and after spraying on the wall surface or exposed surface, the concrete, etc. is immediately hardened. I need to let you.
In addition, it is necessary to secure the usable time of mortar and concrete and to cure them immediately even in water stoppage work and emergency work.

Conventionally, as a cement having a fast-hardening property, a hard-hardening cement such as a jet cement has been manufactured. Examples of the clinker used for these include a jet cement clinker, an Irwin clinker containing C4A3S as a main component, an alumina cement clinker containing CA as a main component, and the like.
There is also a method of obtaining amorphous C12A7 by melting a clinker containing C12A7, which is a rapidly hardening component, as a main component, and then quenching the clinker.

In particular, the conventional jet cement clinker is a clinker containing calcium silicate phase as a main component and C11A7 / CaF2 as a fast-curing component in an amount of about 20 to 30% by weight, and is formed by producing a melt phase such as C11A7CaF2 or C4AF. Is. Therefore, if the content of C12A7, which is a rapidly hardening component, is set to the above range or more, the amount of the melt phase becomes too large and the clinker melts, which makes it very difficult to manufacture, for example, in the current equipment.

Further, the Irwin-based clinker is used as a clinker for hard-hardening cement because it contains 70% by weight or more of Irwin (C4A3 S ) having a hard-hardening property. There is a problem that it is inferior in sharpness.
Further, the alumina cement clinker containing CA as a main component is inferior in rapid hardness to the clinker containing C12A7 as a main component.

As for the fast-hardening clinker, Japanese Patent No. 4616113 (Patent Document 1) states that the content of C12A7 or C11A7 / CaX2 (X indicates halogen) before firing in a reducing atmosphere is 20 to 30% by mass. , C12A7 or C11A7 · CaX2 (X indicates halogen) was calcined at 1300 to 1380 ° C. in a reducing atmosphere, and the lattice constant measured by X-ray diffraction was 11.93 to 11.96 Å. A characteristic, hard-hardening clinker is disclosed.

Further, Japanese Patent No. 3179702 (Patent Document 2) describes a clinker composition used for hard-hardening cement, quick-setting material, quick-hardening cement, ground improvement material, masking material, etc., and has 12CaO as a mineral phase.・ A clinker raw material containing 7Al ₂ O ₃ calcium aluminate as a main component contains 0.1 to 9% by weight of Fe ₂ O ₃ and 0.1 to 9% by weight of CaF ₂ in coexistence. By forming a low-temperature melt phase and a high-temperature melt phase, and adding 0.5 to 9% by weight of TiO ₂ to the whole, the start temperature of melt formation between the low-temperature melt phase and the high-temperature melt phase can be adjusted. Disclosed is a fast-hardening clinker composition characterized by being lowered and fired.

In these conventional cement clinker, it is necessary to positively generate a melt phase in order to promote the solid phase reaction, and if the amount of the melt phase is small, the solid phase reaction does not proceed and the clinker mineral production does not proceed well. On the other hand, excessive formation of the melt phase poses a problem in the production of clinker, so it is necessary to adjust the amount of the melt phase to be formed so as to be within a certain range.
In particular, the clinker of Patent Document 2 and the like has a C12A7-based mineral content increased as compared with the jet clinker, and produces a C12A7-based mineral phase by a solid-phase reaction. At this time, Fe and Ti are added to generate an appropriate amount of melt phase to obtain a clinker.
Further, the C12A7-based mineral of the conventional clinker is a solid solution, and the solid-dissolved state of the C12A7-based mineral changes depending on the content of Fe and Ti, which affects the hydration activity of the C12A7-based mineral.

However, it has been difficult to sufficiently develop the desired rapid hardness, for example, strength for 3 hours, and to sufficiently secure the fluidity of cement not only at room temperature but also in high temperature season such as summer. This is because the conditions for producing an appropriate amount of melt phase required for producing clinker do not always match the solid solution state of the rapidly rigid component, that is, the conditions for maximizing the hydration activity, and the rapidly rigid component It is related to the difficulty of designing to maximize the hydration activity of.
Furthermore, these clinker are materials used in the production of cement and are used to post-add to any cement to increase the hydration activity of the resulting cement during utilization and to obtain any desired fast hardness. is not it.

Japanese Patent No. 4616113 Japanese Patent No. 3179702

An object of the present invention is to exhibit sufficient strength not only at room temperature but also at high temperature such as summer, exhibit excellent hydration activity and good rapid hardening performance, and secure sufficient fluidity for construction. It is an object of the present invention to provide a fast-hardening additive for cement and a method for producing the same, which have excellent properties.

The hard-hardening additive for cement according to claim 1 has a C12A7-based mineral phase of 70% by mass or more, C2S of 25% by mass or less, C3A of 5% by mass or less, CA of 10% by mass or less, and C2AS of 20% by mass or less. It is a hard-hardening additive for cement, which is characterized by containing in.

The hard-hardening additive for cement according to claim 1 is a hard-hardening additive for cement , further comprising C4AF in an amount of 0.5% by mass or less.

The hard-hardening additive for cement according to claim 1 is a hard-hardening additive for cement, characterized in that the total mass of CaO and MgO and the remaining mineral phase is 15% by mass or less.

The hard-hardening additive for cement according to claim 2 is the hard-hardening additive for cement according to claim 1 , further containing Fe ₂ O ₃ in an amount of 5% by mass or less, and the L * value determined by the CIE color difference formula is , L * ≧ -3.4 × Fe ₂ O ₃ +55, which is a hard additive for cement.

The hard-hardening additive for cement according to claim 3 is the hard-hardening additive for cement according to claim 1 or 2 , wherein the L * value determined by the CIE color difference formula is 67 to 85. It is a hard additive.

The method for producing a hard-hardening additive for cement according to claim 4 has a C12A7-based mineral phase of 70% by mass or more, C2S of 25% by mass or less, C3A of 5% by mass or less, CA of 10% by mass or less, and C2AS of 20. Raw materials are blended and powdered so that the total mass of CaO and MgO and the remaining mineral phase is 15% by mass or less, C4AF is 0.5% by mass or less, and the powdered raw material is calcined. For cement, the oxygen concentration at the time of firing is adjusted so that the L * value of the obtained fired body is in the range of the formula L * ≧ -3.4 × Fe ₂ O ₃ +55. This is a method for producing a hard-hardening additive.

By mixing the hard-hardening additive for cement of the present invention with any cement, the obtained mortar or the like can sufficiently secure fluidity to obtain excellent workability and improve hydration activity. It is possible to show the desired excellent initial intensity for 3 hours.
Therefore, it can be effectively applied at work sites and the like in hard-hardening applications, and further, the hard-hardening additive for cement of the present invention can be easily adjusted and added in an arbitrary amount according to a desired initial strength. In addition to facilitating the design to obtain the desired sharp hardness, it is possible to improve the workability not only at room temperature but also at high temperature such as summer of 30 ° C. or higher.
Further, it is possible to have a fluidity such as a mortar using the hard additive for cement of the present invention, which improves pumping property, for example.

The method for producing a hard-hardening additive for cement of the present invention can effectively manufacture the hard-hardening additive for cement of the present invention, does not require special equipment or equipment, and utilizes existing equipment. Therefore, the above-mentioned hard-hardening additive for cement of the present invention can be economically and effectively produced.

The present invention will be described in the following form, but the present invention is not limited thereto.
The hard-hardening additive for cement of the present invention contains C12A7-based mineral phase in an amount of 70% by mass or more, C2S in an amount of 25% by mass or less, C3A in an amount of 5% by mass or less, CA in an amount of 10% by mass or less, and C2AS in an amount of 20% by mass or less. , A hard additive for cement.
The hard-hardening additive for cement of the present invention contains C 4AF in an amount of 0.5% by mass or less, and has a total mass of CaO (free lime) and MgO (periclase) and the remaining mineral phase of 15% by mass or less. ..
Here, the "remaining mineral phase" means a mineral phase other than C12A7-based mineral phase, C2S, C3A, CA, C2AS, CaO and MgO in the hard-hardening additive for cement, and the "remaining mineral phase" is used. "Does not contribute to the initial hydration reaction.

That is, the hard-hardening additive for cement of the present invention is an additive containing a C12A7-based mineral phase as a main component, and has C2S of 25% by mass or less, C3A of 5% by mass or less, CA of 10% by mass or less, and C2AS. Is contained in an amount of 20% by mass or less, preferably C4AF is contained in an amount of 0.5% by mass or less, and more preferably, the total mass of the remaining mineral phases other than CaO and MgO and C2S, C3A, CA and C2AS is 15% by mass or less. As a result, mortar and the like obtained by adding to cement that can be obtained in any market can secure excellent fluidity not only at room temperature but also in high temperature range and have excellent workability. It is possible to improve the initial strength for 3 hours.

The hard-hardening additive for cement of the present invention contains 70% by mass or more, preferably 83% by mass or more, of a C12A7-based mineral phase which is a calcium aluminate phase.
Therefore, the C12A7-based mineral phase can be contained in a high content and the hydration activity can be improved, and as a result, the above-mentioned effect of the present invention can be sufficiently exhibited.
If the content of the C12A7-based mineral phase is less than 70% by mass, sufficient rapid hardness cannot be obtained, the initial strength is lowered, and the above-mentioned effect of the present invention cannot be obtained.
Here, the C12A7-based mineral phase corresponds to C12A7 or C11A7 / CaX2 (X is a halogen such as F, Cl, Br, etc.), and may be a mixed phase thereof.

Further, C2S contained in the hard-hardening additive for cement of the present invention is 25% by mass or less, preferably 20% by mass or less, and it is desirable that it is not substantially contained, and C3A is 5% by mass or less. It is desirable that it is not substantially contained, and further, CA is 10% by mass or less, preferably 5% by mass or less, and it is desirable that it is not substantially contained, and C2AS is 20% by mass or less, preferably 10% by mass or less. It is desirable that it is not substantially included.
If each of the above minerals, C2S, C3A, CA, and C2AS, is contained in excess of each of the above ranges, the content of the C12A7-based mineral contained in the hard-hardening additive for cement is reduced, and the present invention It becomes impossible to exert the above-mentioned effect of.
Here, "substantially free" means that these mineral phases are not prevented from being produced by using a raw material rich in Si, Ca or Al, which are impurities contained in the raw material. Therefore, it is not actively produced and contained.

Further, it is desirable that the hard-hardening additive for cement of the present invention containing the C12A7-based mineral phase as a main component and having a C2S, C3A, CA, C2AS content of a certain level or less is substantially free of C4A3S. ..
The fact that it is not substantially contained means that it does not prevent the case where it is produced by SO ₃ which is an impurity contained in the raw material, and does not mean that it is positively produced and contained.
In this specification, S means SO ₃ and S means SiO ₂ .

Further, it is desirable that Fe ₂ O ₃ is not substantially contained in the hard-hardening additive for cement of the present invention. For example, the content of Fe is 5% by mass or less in terms of Fe ₂ O ₃ oxide. Since it is preferably 1.5% by mass or less, the contained C4AF is 0.5% by mass or less. Substantially, C4AF is hardly generated and is not included.

Further, the hard-hardening additive for cement of the present invention has a total content of MgO, CaO, and mineral phases other than the above-mentioned C2S, C3A, CA and C2AS (remaining mineral phase) of 15% by mass or less, preferably 15% by mass or less. It is preferably 12% by mass or less.
If it exceeds 15% by mass, the content of the C12A7-based mineral contained in the hard-hardening additive for cement becomes small, and the above-mentioned effect of the present invention may not be exhibited, which is not desirable.

Further, the hard-hardening additive for cement of the present invention can more effectively exhibit the effect of the present invention by satisfying the following formula.
L * ≧ −3.4 × Fe ₂ O ₃ +55
In the formula, L * indicates the color difference value (L * value) obtained by the CIE color difference formula of the rapid-hardening additive for cement of the present invention, and for example, a color difference meter (CR-300) manufactured by Konica Minolta Japan Co., Ltd. ) Is the value of the brightness (L * value) specified by the CIE (International Commission on Illumination), and Fe ₂ O ₃ is the oxide-converted amount of Fe contained.
If the degree of reduction during firing when preparing a hard additive for cement is too high, the L * value will decrease, the activity of the C12A7 system will decrease, and the initial strength will be insufficient. If the Fe ₂ O ₃ content in the material exceeds the above-mentioned content range, the L * value decreases, but if it is the above-mentioned Fe ₂ O ₃ content range, it does not matter.
The above formula shows the range for the elements whose L * value decreases due to the Fe ₂ O ₃ content and the elements whose L * value decreases due to reduction firing, so that the L * value satisfies the above formula. Try to adjust the oxygen concentration during firing.

Further, the hard-hardening additive for cement of the present invention has an L * value of 67 to 85 determined by the CIE color difference formula.
If the L * value is out of the above range, the activity of the contained C12A7 system is lowered, and the initial strength expression is deteriorated, which is not desirable. If the Fe ₂ O ₃ content in the hard-hardening additive for cement exceeds the above-mentioned content range, the L * value decreases, but if it is the above-mentioned Fe ₂ O ₃ content range, it does not matter. However, the L * value can be 67 to 85.

The hard-hardening additive for cement of the present invention includes calcium raw materials such as fresh lime, slaked lime, and limestone, aluminum hydroxide, alumina, aluminum raw materials such as bauxite and band spores, magnesium raw materials such as dolomite, and fluorite to be blended as necessary. Fluorine raw materials such as, etc. are mixed and crushed, or crushed and mixed, and this powder mixture is molded to obtain a molded product, which is fired and cooled using a heating furnace such as an electric furnace. Prepare a hard additive for cement.
It should be noted that the material used as a raw material for Fe (for example, red iron oxide) contained in the obtained hardened additive for cement is not positively blended. Fe contained in the obtained hardened additive for cement may be contained as an impurity in the compounding raw material, and may be contained as a result, but is not positively contained.

Specifically, the hard-hardening additive for cement of the present invention is a molded product obtained by powdering and mixing the compounding raw materials and molding the mixed powder, for example, 1250 to 1400 ° C., preferably 1300 to 1360 ° C. It can be produced by firing sufficiently at the temperature of, for example, 0.5 to 3 hours, and then cooling at a cooling rate of 40 ° C./min or less, preferably 5 to 40 ° C./min. The raw materials are blended so as to have the content ratio in the present invention.
By adjusting the content of each of the above minerals as described above, the workability at room temperature and high temperature is excellent, and the strength development for 3 hours is excellent.

In this way, the raw material mixed powder is fired, and if necessary, the molded body is fired and cooled at a cooling rate of, for example, 40 ° C./min or less, preferably 5 to 40 ° C./min. The oxygen concentration during such firing is measured, and the L * value of the obtained hardened cement additive is measured, so that L * ≧ −3.4 × Fe ₂ O ₃ +55 can be satisfied, preferably L *. Air or the like is introduced at the time of firing so that the value is within the range of 67 to 85, and the oxygen concentration is adjusted.
That is, in order to secure good fluidity and secure pot life and obtain rapid hardness, it is preferable to perform firing at the above-mentioned firing temperature or the like, cool at the above-mentioned cooling rate, and adjust the oxygen concentration. It is possible to obtain a quenching additive for cement.

The hard-hardening additive for cement of the present invention is crushed into a hard-hardening additive powder for cement, and the powder is blended with arbitrary cement, for example, ordinary Portland cement or the like together with sulfate or the like to obtain a hard-hardening cement composition. It is possible to use it.
The hard-hardening additive for cement of the present invention is preferably used after being pulverized to a brain specific surface area of 4500 cm ² / g or more, and if it is less than 4500 cm ² / g, good hard-hardening may not be obtained. Because.
Further, if the specific surface area of the brain is too large, the fluidity is adversely affected, the crushing time is required, the productivity is lowered, and the cost is high. Therefore, 5000 to 7000 cm ² / g is desirable.
Further, when pulverizing, a pulverizing aid (diethylene glycol, triethanolamine, etc.) may be added.

Any commercially available cement can be applied as the cement to which the hard-hardening additive for cement of the present invention is blended, for example, early-strength Portland cement, ultra-early-strength Portland cement, ordinary Portland cement, and moderate. At least one selected from hot Portland cement, low heat Portland cement, sulfate resistant Portland cement, fly ash cement, blast furnace cement, silica cement and the like can be used.

Examples of the sulfate include alkali metal sulfates such as Glauber's salt (sodium sulfate) and potassium sulfate, alkaline earth metal sulfates such as magnesium sulfate and gypsum (calcium sulfate), and aluminum sulfate. From the viewpoint of sex, the use of gypsum or the combined use of gypsum and Glauber's salt is preferable.
Examples of gypsum include anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, or a mixture thereof.
In addition, slaked lime can be mentioned as another material that can be blended as needed.

The method for mixing the hard-hardening additive for cement, cement, sulfate, water, etc. of the present invention is not particularly limited, and the mixture may be mixed in a predetermined ratio and then mixed using a conventional mixing device.
In addition, coagulation adjusters (lignin sulfonic acid type, oxycarboxylic acid type, various organic acids such as saccharides or alkali metal salts of organic acids and alkaline earth metal salts) and water reducing agents (alkylallyl sulfonic acid type, naphthalene sulfonic acid). Liquid or powder admixtures such as system, melamine sulfonic acid system, polycarboxylic acid system, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, and fine aggregate (river sand, sea sand, mountain). Sand, crushed sand and a mixture thereof), coarse aggregate (river gravel, sea gravel, crushed stone and a mixture thereof) and the like can be blended.

As described above, by adding the hard-hardening additive for cement of the present invention to any cement, for example, fluidity can be ensured not only at room temperature but also at high temperature such as summer, and the workability can be improved. It is excellent, has good strength development for 3 hours, can obtain the desired sharp hardness in the field, and it is extremely easy to operate the design to obtain good initial strength development while ensuring workability. Is possible.

The present invention will be described with reference to the following examples, comparative examples and test examples.
(Examples 1 to 19, comparative examples 1 to 15)
1) Preparation of hard-hardening additive for cement As shown in Tables 1 to 3 below, raw materials of limestone, fluorite, aluminum hydroxide, iron oxide, titanium oxide and silica sand are mixed and powdered, and pressure-molded. Then, each molded product is calcined in an electric furnace at 1300 ° C. for 30 minutes at each oxygen concentration shown in Tables 1 to 3, and then cooled at a cooling rate of 40 ° C./min to obtain a fast-hardening additive for each cement. Obtained

2) Mineral analysis of hard-hardening additives for cement The obtained hard-hardening additives for cement were subjected to X-ray diffraction / Rietveld method (device: X'Pert MPD manufactured by PANalytical Co., Ltd., analysis software: HighScorePlus). , C12A7 series, C2S, C3A, CA, C2AS, C4AF, C4A3S , CaO (free lime) and MgO (periclase) were measured. The results are shown in Tables 1 to 3.
In the table, the amount of minerals other than the above minerals is indicated as "other".
Tube voltage: 45kV Tube current: 40mA

3) Measurement of Fe component content The obtained hard-hardening additive for cement was analyzed and contained according to JIS R 5204 using a fluorescent X-ray analyzer (manufactured by PANalytical Co., Ltd .; Axios). The content ratio of the Fe component was measured.
The results are shown in Tables 1 to 3.
However, as the Fe component, Fe contained in the hard additive for cement was converted into Fe ₂ O ₃ and displayed.

4) Measurement of color tone The color tone of the obtained hard additive for cement was specified by the CIE (International Commission on Illumination) using a color difference meter (CR-300) manufactured by Konica Minolta Japan Co., Ltd. It was measured by the value of brightness (L value). The results are shown in Tables 1 to 3.

5) Preparation of mortar Next, the above-mentioned hard-hardening additive for cement was pulverized to a brain specific surface area of about 5200 ± 200 cm ² / g to obtain a hard-hardening additive powder for each cement.
Fast-hardening additive powder for each cement, anhydrous gypsum (reagent, brain specific surface area 6800 cm ² / g), Na ₂ SO ₄ (reagent) and slaked lime in early-strength cement (HC: manufactured by Sumitomo Osaka Cement Co., Ltd.) (Reagent) was blended in the blending ratio shown in Table 4 below to prepare a cement composition.
A coagulation adjuster (reagent; tartrate acid, manufactured by Wako Pure Chemical Industries, Ltd.) was added to each of the cement compositions in the ratio shown in Table 4 by external division with respect to the cement composition, and water was added to the cement composition. As shown in Table 4 below, they were mixed and kneaded uniformly so that the cement composition substance amount ratio was 0.38, and each mortar was obtained.

(Test example)
1) Intensity measurement and flow value measurement For each mortar obtained above, the strength (initial intensity) at 30 ° C. for 3 hours and the flow value at 30 ° C. were measured according to JIS R 5201.
The results are also shown in Tables 1 to 3 above.

2) Condensation time For each mortar obtained above, the condensation time of each mortar was measured according to JIR R5201 (physical test method for cement).
However, as the closing needle, a conical needle having a diameter of 1 inch and a height of 2 inches was used, and the time when the penetration depth became 1.5 mm was defined as the setting (closing) time.

In the above test, those having a flow value of 250 mm or more, a setting time of 40 minutes or more and a strength of 25 N / mm ² or more for 3 hours are marked with ⊚, and a flow value of 200 mm or more, a setting time of 30 minutes or more and a setting time of 30 minutes or more. Those having a physical property of 20 N / mm ² or more for 3 hours are evaluated as ◯, and the evaluation results are also shown in Tables 1 to 3.

From Tables 1 to 3 above, the examples of the present invention can impart good initial strength to the cement not only at room temperature but also at high temperatures such as summer, and have a predetermined fluidity. It can be seen that it is excellent in workability by ensuring sufficient.

By adding the hard-hardening additive for cement of the present invention to any cement, it becomes easy to design the desired hard-hardening not only at room temperature but also at high temperature such as summer, and it becomes easy to design the desired hardness in tunnels and underground spaces. Construction work, civil engineering work, water stoppage work, spraying work on walls, etc., repair work on urgent roads, etc., and as a soil improvement material, while ensuring a predetermined handling time, promptly after the pot life has elapsed It can be usefully applied to work places where strength is required to be exhibited.

Claims (4)

Contains 70% by mass or more of C12A7 mineral phase, 25% by mass or less of C2S, 5% by mass or less of C3A, 10% by mass or less of CA, 20% by mass or less of C2AS, 0.5% by mass or less of C4AF, and CaO. A rapid-hardening additive for cement, wherein the total mass of MgO and the remaining mineral phase is 15% by mass or less . In the hard-hardening additive for cement according to claim 1 , Fe ₂ O ₃ is further contained in an amount of 5% by mass or less, and the L * value determined by the CIE color difference formula is the formula L * ≧-3.4 × Fe ₂ O. A hard-hardening additive for cement, characterized by a range of ₃ +55. The hard-hardening additive for cement according to claim 1 or 2 , wherein the L * value determined by the CIE color difference formula is 67 to 85. C12A7 mineral phase is 70% by mass or more, C2S is 25% by mass or less, C3A is 5% by mass or less, CA is 10% by mass or less, C2AS is 20% by mass or less , C4AF is 0.5% by mass or less, CaO and MgO. In addition, the L * value of the calcined product obtained by blending and pulverizing the raw materials so that the total mass of the remaining mineral phase is 15% by mass or less and calcining the pulverized raw materials is the formula L * ≧ -3. .. A method for producing a hard additive for cement, which comprises adjusting the oxygen concentration at the time of firing so as to be in the range of 4 × Fe ₂ O ₃ +55 and firing.