JP5189917B2 - Cement admixture and cement composition - Google Patents

Description

  The present invention mainly relates to a cement admixture and a cement composition used in the civil engineering and construction industries.

  With regard to the durability of mortar and concrete, not only engineers in this field but also the general public has come to receive great attention. There are various causes of deterioration of mortar and concrete. One of them, the “alkali silica reaction” derived from the quality of the aggregate, the so-called “alkali aggregate reaction” is also called concrete cancer, and no effective suppression method has been found.

  As a method of suppressing the “alkali silica reaction”, a method of adding an alkali aggregate reaction inhibitor or a method of impregnating or applying concrete is proposed (Patent Documents 1 to 5). However, these alkali-aggregate reaction inhibitors are not practical and are not practical from the viewpoint of economy because they are mixed with concrete and are used in large amounts. Therefore, development of a cement admixture that exhibits an excellent effect with a smaller addition amount is desired.

JP-A-62-278151 Japanese Patent Laid-Open No. 10-167781 JP-A-63-274644 JP 2006-62892 A JP 2006-89334 A

  On the other hand, a number of quick setting agents for mortar and concrete have been proposed and used as spray concrete for tunnels, for example (Patent Documents 6 to 10).

Japanese Patent Laid-Open No. 02-83245 JP-A-63-112448 JP-A-8-310850 JP-A-10-212149 Japanese Patent Laid-Open No. 2005-97060

The quick setting agent used for mortar and concrete contains a large amount of potassium and sodium that promote the alkali-aggregate reaction, so there is a concern about the influence on the alkali-aggregate reaction.
As a method for suppressing the alkali aggregate reaction, a method using a mixed cement substituted with blast furnace slag or fly ash, or a shotcrete using a rapid setting agent with little sodium or potassium is known. (Patent Documents 11 to 14).

Japanese Patent Laid-Open No. 10-101390 JP 2004-331423 A JP-A-2005-75668 JP 2006-191390 A

  Mixed cements replaced with blast furnace slag and fly ash, and quick setting agents with low sodium and potassium, are prone to delay in the initial setting, insufficient stabilization of the ground, and increased rebound rate . Increasing the addition rate can improve the setting properties, but there are problems such as increased dust generation and reduced long-term strength.

  The present inventors have found that the above problem can be solved by applying a cement admixture and a cement composition containing a specific zeolite containing lithium and a rapid setting agent to mortar and concrete.

  The present invention provides a cement admixture and a cement composition that can effectively suppress the alkali silica reaction of mortar and concrete and do not impair the rapid setting force.

That is, the present invention provides: (1) EDI type or ABW type or lithium-type zeolite which is a heat-treated product thereof , calcium aluminate type quick setting agent, calcium sulfoaluminate type quick setting agent, aluminate, carbonate Inorganic salt-based quick-setting agents based on inorganic salts of silicates, quick-setting agents based on aluminum sulfate, titanium-based quick-setting agents based on organic titanium and titanium sulfate, and silicates Ri Na contain quick-setting admixture which is either a rapid setting agent as a component, the content of lithium in the lithium-type zeolite is at least 5% by Li 2 _O conversion, the lithium-type zeolite Na 2 _O and K Cement admixture having a total content of ₂ O of less than 0.5%, 10 to 90 parts of quick setting agent and 10 to 90 parts of lithium type zeolite in a total of 100 parts of lithium type zeolite and quick setting agent , ( 2) cell and the instrument, and also contains the cement admixture of (1), a cement composition 100 parts consisting of cement and a cement admixture, a cement composition is 1 to 30 parts, (3) (2) A method of effectively preventing the alkali silica reaction of mortar and concrete and not impairing the rapid setting force of mortar and concrete .

  ADVANTAGE OF THE INVENTION According to this invention, there exists a remarkable effect that the alkali silica reaction of mortar and concrete can be suppressed effectively, and the rapid setting power of mortar and concrete is not impaired.

  In the present invention, “parts” and “%” are based on mass unless otherwise specified.

Here, the lithium type zeolite will be described.
Among lithium-type zeolites, lithium-type zeolite having a Si / Al atomic ratio of 1 is preferable because the effect of suppressing the alkali silica reaction is large. As the lithium type zeolite having a Si / Al atomic ratio of 1, there are EDI type, ABW type and LTA type.
Of these, EDI type and ABW type can be synthesized easily by using allophane or kaolinite as a raw material and allowing an aqueous lithium hydroxide solution to act at less than 100 ° C. On the other hand, synthesis of LTA requires hydrothermal treatment under pressure conditions exceeding 100 ° C., and it is difficult to directly synthesize LTA containing lithium. Lithium is supported by an ion exchange reaction after obtaining a type zeolite by hydrothermal synthesis. For this reason, it is difficult to completely replace sodium with lithium, and LTA may not provide a sufficient alkaline silica reaction suppression effect. Therefore, in the present invention, it is preferable to select the EDI type and the ABW type.

  The EDI-type zeolite is a general term for zeolites having a structure similar to a compound called Edingtonite.

ABW-type zeolite containing lithium was named for the first time reported by Barrer and White (Barrer RM and White ED, J. Chem. Soc., 1951, 1267). ). That is, it is often written as A (BW) in the meaning of A of zeolite found by Barrer and White. Here, the meaning of A will be supplemented. A is the first letter of the alphabet, meaning “found first” (respect: nomenclature and structure of zeolite, catalyst, Vol. 40, No. 3, pp. 185-190, 1998). ABW-type zeolite containing lithium has about 15 to 25% of crystal water. The SiO ₂ content and the Al ₂ O ₃ content are about 30 ± 5%, respectively.

  As a method for synthesizing a lithium zeolite, a method using silica sol and alumina sol as starting materials (T. Matsumoto et al., Journal of the European Ceramic Society, 26, pp. 455-458, 2006) has been known. It has been. In addition, a method of reacting lithium hydroxide with allophane as a raw material is also known (Yusuke Okino et al., Abstracts of the 112th Academic Lecture Meeting of the Society of Inorganic Materials, pp. 8-9, 2006).

In the present invention, lithium-type zeolite synthesized by any method can be used, and includes those obtained by heat-treating lithium-type zeolite.
The heat treatment temperature varies depending on the zeolite. For example, in the case of EDI type, it is preferable that it is 200-700 degreeC. When the lithium-containing EDI-type zeolite is heat-treated at 200 to 700 ° C., it changes into an amorphous substance. That is, the crystal structure of the EDI-type zeolite is maintained up to 200 ° C., and the crystal changes from amorphous to 200 ° C. or more. And although it is in an amorphous state up to 700 ° C., when it exceeds 700 ° C., it crystallizes and changes to eucryptite.
In the case of the ABW type, 300 to 650 ° C. is preferable. When ABW type zeolite containing lithium is heat-treated at 300 to 650 ° C., it is changed to anhydrous ABW type zeolite. That is, the crystal structure of the ABW type zeolite is maintained up to 300 ° C., and when the temperature exceeds 300 ° C., the crystal structure changes to a completely different crystal structure to become anhydrous ABW type zeolite. And it is in the state of anhydrous ABW type zeolite up to 650 ° C., but when it exceeds 650 ° C., it changes to γ-eucryptite. And when it heats further, it changes to (beta) -eucryptite at 900-1000 degreeC.
If the heat treatment conditions are not within the above temperature range, there may be a case where a sufficient expansion suppression effect of the alkali silica reaction and an effect of improving the initial setting force cannot be obtained.

The heat treatment referred to in the present invention is not particularly limited, but usually means a treatment such as drying or baking. As a specific method, for example, after allophane is reacted in an aqueous lithium hydroxide solution to form a lithium-type zeolite, a predetermined heat treatment may be performed at the stage of the drying operation. After drying under the above conditions, heat treatment may be performed again under predetermined conditions. The time for the heat treatment is not particularly limited, but is preferably about 5 minutes to 24 hours, and more preferably 10 minutes to 12 hours. If the reaction time is less than 5 minutes, the reaction in which the EDI-type zeolite changes to an amorphous substance or the reaction in which the ABW-type zeolite changes to anhydrous ABW may not proceed sufficiently. It may become.
The drying device is not particularly limited, and a drum dryer, a shelf dryer, a cylindrical dryer, a rotary kiln, an electric furnace, or the like can be used.

The lithium content of the lithium-type zeolite of the present invention is not particularly limited, but is usually preferably 5% or more and more preferably 7% or more in terms of Li ₂ O. The maximum amount of lithium that can be supported can be calculated as 13.5% from the theoretical value at which the Si / Al molar ratio is 1. If the lithium content is less than 5%, there may be a case where a sufficient effect of suppressing expansion due to alkali silica reaction cannot be obtained.

The content of sodium or potassium in the lithium zeolite of the present invention is not particularly limited, but it is usually preferable that the total amount of Na ₂ O and K ₂ O is 0.5% or less. 3% or less is more preferable. When the total amount of Na ₂ O and K ₂ O exceeds 0.5%, there may be a case where a sufficient effect of suppressing expansion due to the alkali silica reaction cannot be obtained.

The specific surface area of the lithium-type zeolite of the present invention is not uniquely determined and is not particularly limited, but is usually in the range of ² to 200 m ² / g in terms of BET specific surface area.

  The quick setting agent used in the present invention is not particularly limited, and any quick setting agent can be used as long as it imparts quick setting property to concrete or mortar. For example, spray concrete or spray mortar. It is intended to provide quick setting. Specifically, calcium aluminate-based quick setting agents, calcium sulfoaluminate-based quick setting agents, inorganic salt-based quick setting agents mainly composed of inorganic salts such as aluminates, carbonates, silicates, aluminum sulfate There are rapid setting agents mainly composed of tantalum, titanium-based rapid setting agents composed mainly of organic titanium and titanium sulfate, and rapid setting agents mainly composed of silicate. The quick setting agent can be used in liquid form, suspension form or powder form.

  The blending ratio of the lithium zeolite and the quick setting agent in the cement admixture is not particularly limited, but usually 10 to 90 parts of the lithium type zeolite is preferable in the total 100 parts of the lithium type zeolite and the quick setting agent, 20-80 parts is more preferable. If the blending ratio of the lithium-type zeolite and the quick setting agent is not within the above range, there may be a case where a sufficient alkaline silica reaction suppressing effect cannot be obtained.

The amount of the cement admixture of the present invention is not particularly limited, usually, a cement composition 100 parts consisting of cement and cement admixture, preferably 1 to 30 parts, more preferably 3 to 20 parts . If it is less than 1 part, the effect of the present invention, that is, the effect of suppressing the expansion due to the alkali silica reaction may not be sufficiently obtained, and if it exceeds 30 parts, further enhancement of the effect cannot be expected. In addition, strength development may be reduced.

  Cement includes various types of Portland cement 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 and blast furnace slow cooling. Portland cement such as filler cement mixed with slag fine powder, etc., and environmentally friendly cement (eco-cement) manufactured using municipal waste incineration ash and sewage sludge incineration ash as raw materials. Two or more types can be used.

  In the cement admixture and cement composition of the present invention, the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance.

  In the present invention, fine aggregates such as sand, coarse aggregates such as gravel, water reducing agents, AE water reducing agents, high performance water reducing agents, high performance AE water reducing agents, antifoaming agents, thickeners, rust preventive agents, antifreeze agents , Shrinkage reducing agents, polymer emulsions, setting modifiers, various additives such as bentonite and other clay minerals and anion exchangers such as hydrotalcite, ground granulated blast furnace slag, ground granulated blast furnace slag and fine limestone powder It is possible to use together 1 type, or 2 or more types of the group which consists of admixture materials, such as a fly ash and a silica fume, in the range which does not inhibit the objective of this invention substantially.

"Example 1"
Cement admixtures were prepared by blending 50 parts of various lithium zeolites shown in Table 1 and 50 parts of various quick setting agents. A cement composition was prepared by blending 10 parts of cement admixture in a total of 100 parts of cement and cement admixture. Furthermore, 225 parts of sand and 50 parts of water were blended to prepare a mortar. Using this mortar, an alkali silica reactivity test was carried out. In addition, a setting test and a compressive strength test were also performed.
In addition, as a comparative example, a test was also conducted when the same amount of a commercially available alkali silica reaction inhibitor was used and when a general quick-setting agent was used. The results are also shown in Table 1.

<Materials used>
Cement A: Commercially available ordinary Portland cement Cement B: Blast furnace cement B type sand: Sanucitic pyroxene andesite, measured according to JIS A 1145 (chemical method). It is determined that the amount of dissolved silica is 750 mmol / l and the decrease in alkali concentration is 200 mmol / l, which is not harmless.
Lithium type zeolite A: EDI type zeolite containing lithium (Li-EDI), Li ₂ O content 7.1%, total content of Na ₂ O and K ₂ O 0.26%, BET specific surface area 50 m ² / G.
Lithium type zeolite B: ABW type zeolite containing lithium (Li-ABW), Li ₂ O content 9.0%, total content of Na ₂ O and K ₂ O 0.27%, BET specific surface area 40 m ² / G.
Lithium-type zeolite C: amorphous material obtained by heat-treating lithium-containing EDI-type zeolite (Li-EDI) at 400 ° C., Li ₂ O content 9.0%, Na ₂ O and K ₂ O Total content of 0.21%, BET specific surface area 30 m ² / g.
Lithium-type zeolite D: anhydrous Li-ABW obtained by heat-treating lithium-containing ABW-type zeolite (Li-ABW) at 400 ° C., Li ₂ O content 10.8%, Na ₂ O and K ₂ The total content of O is 0.19%, and the BET specific surface area is 20 m ² / g.
Commercially available alkaline silica reaction inhibitor (1): Ca-type zeolite Commercially available alkaline silica reaction inhibitor (2): Lithium nitrite aqueous solution (concentration 30%)
Quick setting agent a: calcium aluminate, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Natomic T-5”
Quick setting agent b: calcium sulfoaluminate, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Natomic T-10”
Quick setting agent c: inorganic salt type, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Natomic TL”
Quick setting agent d: Aluminum sulfate system, commercial product, aluminum sulfate aqueous solution, solid content concentration 27%
Quick setting agent e: No. 3 water glass, commercial product quick setting agent f: titanium lactate, commercial product, solid content concentration 39%
Water: tap water

<Measurement method>
Alkali-silica reactivity test (mortar bar method): Measured according to JIS A 1146. Those showing an expansion of 0.100% or more are determined not to be harmless.
Setting test: measuring the time to reach the end time, 20 ° C
Compressive strength: Measured according to JIS R 5201. Age 28 days

<Synthesis of lithium-type zeolite>
Lithium-type zeolite was synthesized by reacting allophane and lithium hydroxide as raw materials in water. At this time, the Li ₂ O / Al ₂ O ₃ molar ratio is 2.0, the SiO ₂ / Al ₂ O ₃ molar ratio is 1.73, the reaction temperature is 60 or 90 ° C., the reaction time is 24 hours, The reaction was carried out with stirring. The obtained composite was separated into solid and liquid, washed with warm water at 60 ° C., and dried at 70 ° C. Allophane was used in an amount of 10 kg, and lithium hydroxide was dissolved in water. The lithium hydroxide solution was 100 kg. As a result of identifying the synthesized product by powder X-ray diffractometry (XRD), it was an EDI type zeolite when the reaction temperature was 60 ° C. When the reaction temperature was 90 ° C., it was ABW type zeolite.

<Materials used>
Allophane: water-purified product from Tochigi Prefecture, commercial product, SiO ₂ content 33.6%, Al ₂ O ₃ content 33.1%, Fe ₂ O ₃ content 2.3%, CaO content Amount 0.4%, MgO content 0.1%, Na ₂ O content 0.03%, K ₂ O content 0.02%, ignition loss 30.1%
Lithium hydroxide: Commercial water: Tap water

  From Tables 1, 2, and 3, the setting of the mortar blended with the cement admixture of the present invention is equivalent to the setting property when a general quick setting agent is used, and setting is possible even when using blast furnace cement type B. It can be seen that the time is not delayed and tends to be faster. It can be seen that the strength development is also good. Moreover, in the alkali silica reactivity test, all were 0.100% or less, and were determined to be harmless. On the other hand, when the ratio is varied using commercially available alkali silica reaction inhibitors such as calcium-type zeolite and lithium nitrite, the setting time is delayed and the strength is reduced.

"Example 2"
Example except that cement A was used, lithium type zeolite C and quick setting agent a were used, and the blending ratio of lithium type zeolite C and quick setting agent a in the cement admixture was changed as shown in Table 4. 1 was performed. The results are also shown in Table 2.

  From Table 4, it can be seen that the alkali silica reaction of the mortar is suppressed even when the ratio between the quick setting agent and the lithium zeolite in the cement admixture is changed. Moreover, it turns out that the cement admixture of this invention has the effect of providing a big quick setting force by combining with a quick setting agent, even when the compounding ratio of a quick setting agent is small.

"Example 3"
Cement A is used as the cement, and as the cement admixture, a cement admixture composed of 50 parts of lithium zeolite C and 50 parts of the quick setting agent is used. The amount of the cement admixture used in 100 parts of the cement composition is shown in Table 5. The procedure was the same as in Example 1 except that changes were made. The results are also shown in Table 5.

  Table 5 shows that the alkali silica reaction of the mortar is effectively suppressed even when the amount of the cement admixture of the present invention is changed. It can also be seen that the setting time is shortened by increasing the amount of cement admixture added.

  Since the cement admixture of the present invention can effectively suppress the alkali silica reaction of mortar and concrete with a small addition rate, it is rich in economic efficiency. Further, even when blast furnace cement is used, the setting time can be significantly increased by increasing the addition amount without delaying the setting time. Therefore, it can be widely used in the civil engineering and construction fields.

Claims (3)

EDI-type or ABW-type or lithium-type zeolite, which is heat-treated, and calcium aluminate-based quick setting agent, calcium sulfoaluminate-based quick setting agent, aluminate, carbonate, silicate inorganic salt Either an inorganic salt quick-setting agent as a component, a quick setting agent containing aluminum sulfate as a main component, a titanium-based quick setting agent containing organic titanium or titanium sulfate as a main component, or a quick setting agent containing silicate as a main component Ri Na contain quick-setting admixture is, the content of lithium in the lithium-type zeolite is at least 5% by weight Li 2 _O conversion, the total content of Na 2 _O and K _{2 O} of the lithium-type zeolite A cement admixture that is less than 0.5% by mass and is 10 to 90 parts by mass of the quick setting agent and 10 to 90 parts by mass of the lithium type zeolite in a total of 100 parts by mass of the lithium type zeolite and the quick setting agent . And cement, and also contains the cement admixture according to claim 1, a cement composition 100 parts by mass consisting of cement and a cement admixture, a cement composition is 1 to 30 parts by weight.   A method of using the cement composition according to claim 2, wherein the alkali silica reaction of mortar and concrete can be effectively suppressed and the rapid setting force of mortar and concrete is not impaired.