JP4822498B2 - Cement admixture and cement composition - Google Patents
Cement admixture and cement composition Download PDFInfo
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本発明は、セメント混和剤及びこれを用いたセメント組成物に関し、詳しくは、硬化体の乾燥収縮率が小さく、且つ膨張性状が良好でその保持に優れるセメント組成物が得られるセメント混和剤及びこれを用いたセメント組成物に関する。 The present invention relates to a cement admixture and a cement composition using the same, and in particular, a cement admixture from which a dry shrinkage rate of a cured product is small, and a cement composition having good expansion properties and excellent retention thereof can be obtained. The present invention relates to a cement composition using
一般に、セメントモルタルやセメントコンクリート等は、硬化後に乾燥収縮が起こる。この乾燥収縮により、ひび割れが発生することがある。この乾燥収縮によるひび割れの発生を低減する方法として、膨張材を用いる方法がある。この膨張材を用いる方法は、膨張材中の成分からエトリンガイトや消石灰等の水和生成物の結晶が成長することを利用し、セメントモルタル等の硬化体を予め膨張させておくことにより、その後に硬化体が乾燥収縮してもこの収縮による応力を小さくし、硬化体のひび割れを発生し難くする。また、別な乾燥収縮によるひび割れの発生を低減する方法として、乾燥収縮低減剤を用いる方法がある。この乾燥収縮低減剤は、硬化体中の自由水の表面張力を低減することにより、乾燥収縮率を低減し、硬化体のひび割れ発生を低減する。このような膨張材と乾燥収縮低減剤を併用することも知られている（例えば、特許文献１及び特許文献２）。
In general, cement mortar, cement concrete, and the like undergo drying shrinkage after curing. This drying shrinkage may cause cracks. As a method for reducing the occurrence of cracks due to drying shrinkage, there is a method using an expanding material. The method using the expanding material is based on the fact that crystals of hydration products such as ettringite and slaked lime grow from the components in the expanding material, and by expanding the cured body such as cement mortar in advance, Even if the hardened body shrinks by drying, the stress due to the shrinkage is reduced, and the hardened body is hardly cracked. Another method for reducing the occurrence of cracks due to drying shrinkage is to use a drying shrinkage reducing agent. This drying shrinkage reducing agent reduces the dry shrinkage rate by reducing the surface tension of free water in the cured body, and reduces the occurrence of cracks in the cured body. It is also known to use such an expanding material in combination with a drying shrinkage reducing agent (for example,
しかし、発明者等の研究により、膨張材と乾燥収縮低減剤を単に併用するだけでは、乾燥収縮低減剤を用いずに同量の膨張材単独使用のときに比べ最大膨張率が著しく低下するため、硬化体の乾燥収縮率が大きく且つひび割れ発生の低減が不充分となるという問題があることが分かった。図１は、この事実を示す長さ変化試験結果の模式的なグラフである。
本発明は、前記問題に鑑みてなされたもので、セメントモルタルやセメントコンクリート等の硬化体の乾燥収縮率が小さく且つひび割れの発生が少ないセメント混和剤及びセメント組成物を提供することであり、詳しくは、膨張材に乾燥収縮低減剤を併用することによる硬化体の最大膨張率の低下を防ぎ、即ち膨張材と乾燥収縮低減剤を併用するときの硬化体の最大膨張率が大きく、硬化体の乾燥収縮率が小さく且つ硬化体のひび割れの発生が少ないセメント混和剤及びセメント組成物を提供することを目的とする。 The present invention has been made in view of the above problems, and is to provide a cement admixture and a cement composition having a low drying shrinkage rate and a low occurrence of cracks in hardened bodies such as cement mortar and cement concrete. Prevents a decrease in the maximum expansion coefficient of the cured body by using a drying shrinkage reducing agent in combination with the expansion material, that is, when the expansion material and the drying shrinkage reducing agent are used in combination, the maximum expansion coefficient of the cured body is large. It is an object of the present invention to provide a cement admixture and a cement composition having a low drying shrinkage ratio and less occurrence of cracks in a cured product.
本発明者等は、鋭意検討した結果、膨張材と乾燥収縮低減剤に加え、特定の無機塩を併用することで上記課題を解決することを見出し、本発明を完成した。即ち、本発明は、以下の（１）又は（２）で表すセメント混和剤、並びに（３）又は（４）で表すセメント組成物である。
（１）膨張材、乾燥収縮低減剤及びアルカリ金属塩を含有し、膨張材１００重量部に対して、乾燥収縮低減剤が２〜３０重量部、アルカリ金属塩が０．０１〜２．０重量部であり、膨張材がＪＩＳ Ａ ６２０２「コンクリート用膨張材 」に適合する石灰系膨張材又はエトリンガイト系膨張材であり、乾燥収縮低減剤が下記式（１）で表される化合物を有効成分とするものであり、アルカリ金属塩がアルカリ金属アルミン酸塩、アルカリ金属炭酸塩及びアルカリ金属硫酸塩から選ばれる一種又は二種以上であるセメント混和剤。
ＲＯ（ＡＯ） ｎ Ｈ （１）
（式中、Ｒは水素、炭素数１〜６のアルキル基又は炭素数５〜６のシクロアルキル基、Ａは炭素数２〜３の１種または２種のアルキレン基、ｎは１〜１００の数）
（２）アルカリ金属塩が、炭酸ナトリウム又は／及び硫酸ナトリウムである上記（１）のセメント混和剤。（３）セメントと、上記（１）又は（２）のセメント混和剤一種又は二種以上を含むセメント組成物。（４）上記セメント混和剤の使用量が、セメント組成物１００重量部に対して、膨張材、乾燥収縮低減剤及びアルカリ金属塩の合計が０．３〜５．０重量部となる量である上記（３）のセメント組成物。
As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by using a specific inorganic salt in combination with an expansion material and a drying shrinkage reducing agent, and thus completed the present invention. That is, the present invention is a cement admixture represented by the following (1) or (2 ) and a cement composition represented by (3) or (4).
(1) Contains an expanding material, a drying shrinkage reducing agent, and an alkali metal salt, and 2 to 30 parts by weight of the drying shrinkage reducing agent and 0.01 to 2.0 weight of the alkali metal salt with respect to 100 parts by weight of the expanding material The expansion material is a lime-based expansion material or ettringite-based expansion material that conforms to JIS A 6202 “Expanding material for concrete”, and the dry shrinkage reducing agent is a compound represented by the following formula (1) as an active ingredient It is intended to include alkali metal salts are alkali metal aluminates, one or two or more der Ru cement admixture selected from alkali metal carbonates and alkali metal sulfates.
RO (AO) n H (1)
Wherein R is hydrogen, an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 5 to 6 carbon atoms, A is one or two alkylene groups having 2 to 3 carbon atoms, and n is 1 to 100. number)
(2) The cement admixture according to the above (1), wherein the alkali metal salt is sodium carbonate and / or sodium sulfate . (3) cement and, above (1) or (2) the cement admixture one or cement composition comprising two or more. (4) The amount of the cement admixture used is an amount such that the total of the expansion material, the drying shrinkage reducing agent, and the alkali metal salt is 0.3 to 5.0 parts by weight with respect to 100 parts by weight of the cement composition. Cement composition of said (3) .
本発明によれば、セメントモルタルやセメントコンクリート等の硬化体の乾燥収縮率が小さく且つひび割れの発生が少ないセメント混和剤及びセメント組成物が得られる。本発明によれば、土木学会コンクリート標準示方書「膨張コンクリート設計施工指針」に示されている収縮補償用コンクリートに必要な、材齢７日の膨張率を１５０〜２５０×１０−６の範囲に保持でき、材齢２８日の乾燥収縮ひずみが１５０×１０−６以下の物性を有するセメント混和剤、及びセメント組成物が得られる。本発明のセメント混和剤及びセメント組成物は、セメントモルタルやセメントコンクリート等の硬化体の乾燥収縮率が小さく且つひび割れの発生が少ないので、高耐久性の硬化体が得られる。特に、壁、柱、梁、床等の外気と接する面積が大きいときでも、乾燥収縮によるひび割れが少ない壁、柱、梁、床等が得られる。また、鉄筋等の金属を内蔵するコンクリート等に本発明を用いると、乾燥収縮によるひび割れが著しく低減し、このようなコンクリートを用いる構造物は、乾燥収縮によるひび割れが少ない高耐久性の構造物となる。 According to the present invention, it is possible to obtain a cement admixture and a cement composition in which a hardened body such as cement mortar or cement concrete has a low drying shrinkage rate and less cracking. According to the present invention, the expansion rate required for the concrete for shrinkage compensation shown in the Japan Society of Civil Engineers Concrete Standard Specification “Expanded Concrete Design and Construction Guidelines” is within the range of 150 to 250 × 10 −6 . A cement admixture and a cement composition that can be retained and have a physical property of a drying shrinkage strain of 28 days of age of 150 × 10 −6 or less are obtained. Since the cement admixture and the cement composition of the present invention have a low drying shrinkage rate of hardened bodies such as cement mortar and cement concrete and are less likely to crack, a highly durable hardened body can be obtained. In particular, walls, columns, beams, floors, etc. that are less likely to crack due to drying shrinkage can be obtained even when the area in contact with the outside air, such as walls, columns, beams, floors, is large. In addition, when the present invention is used for concrete containing a metal such as a reinforcing bar, cracks due to drying shrinkage are remarkably reduced, and a structure using such a concrete is a highly durable structure with few cracks due to drying shrinkage. Become.
本発明で使用する膨張材としては、水和により例えば水酸化カルシウムやエトリンガイト等の水和物の結晶が成長し、嵩体積が大きくなる物質であれば何れのものでも良く、具体的には、生石灰、カルシウムサルホアルミネート、石膏、マグネシア、石灰系膨張材、エトリンガイト系膨張材などがあり、これら又はこれらに類する物質の一種又は二種以上を使用することが可能である。ＪＩＳ Ａ ６２０２「コンクリート用膨張材 」に適合する石灰系膨張材又はエトリンガイト系膨張材が、混和量に対する膨張率が安定しているので、混和量に対するモルタルやコンクリート等の硬化体のひび割れ発生を抑制する性能も安定しているので好ましい。 The expansion material used in the present invention may be any material as long as the hydrate crystal such as calcium hydroxide or ettringite grows by hydration and the bulk volume is increased. Specifically, There are quick lime, calcium sulfoaluminate, gypsum, magnesia, lime-based expansive material, ettringite-based expansive material, and the like, or one or more of these substances can be used. The expansion rate of lime-based or ettringite-based expandable material that conforms to JIS A 6202 “Concrete expandable material” has a stable expansion coefficient with respect to the amount of mixing, so that the occurrence of cracks in cured bodies such as mortar and concrete with respect to the amount of mixing is suppressed. It is preferable because the performance is stable.
本発明で使用する乾燥収縮低減剤としては、硬化体中の水分が蒸発する際に発生する応力を低下させる機能を有する物質であれば何れのものでも良く、例えば、ポリオキシアルキレン化合物、ポリエーテル系化合物あるいはアルキレンオキシド化合物等があり、具体的には、ポリオキシエチレン・アルキルアリルエーテル、ポリプロピレングリコール、低級アルコールアルキレンオキシド付加物、グリコールエーテル・アミノアルコール誘導体、ポリエーテル、ポリオキシアルキレングリコール、エチレンオキシドメタノール付加物、エチレンオキシド・プロピレンオキシド重合体、フェニル・エチレンオキシド重合体、シクロアルキレン・エチレンオキシド重合体あるいはジメチルアミン・エチレンオキシド重合体等が例示でき、これらの一種又は二種以上を使用できる。このような乾燥収縮低減剤は、モルタルやコンクリート等の硬化体中の水分が蒸発する際に発生する応力を低下させることにより、モルタル・コンクリート硬化体の乾燥収縮を低減させる性質を有し、より詳しくは、収縮を支配する毛細管空隙の水に溶解して表面張力を低下させ、その結果、乾燥時の毛細管張力を小さくして収縮を低減させるものである。特に、乾燥収縮低減剤が、下記式（１）で表される化合物を有効成分とするものであると、膨張材と混合し長期間貯蔵した場合に品質が安定するので好ましい。
ＲＯ（ＡＯ）ｎＨ （１）
（式中、Ｒは水素、炭素数１〜６のアルキル基又は炭素数５〜６のシクロアルキル基、Ａは炭素数２〜３の１種または２種のアルキレン基、ｎは１〜１００の数）
The drying shrinkage reducing agent used in the present invention may be any substance as long as it has a function of reducing the stress generated when moisture in the cured body evaporates. For example, a polyoxyalkylene compound, a polyether Specific compounds such as polyoxyethylene / alkyl allyl ether, polypropylene glycol, lower alcohol alkylene oxide adduct, glycol ether / amino alcohol derivative, polyether, polyoxyalkylene glycol, ethylene oxide methanol Examples include adducts, ethylene oxide / propylene oxide polymers, phenyl / ethylene oxide polymers, cycloalkylene / ethylene oxide polymers or dimethylamine / ethylene oxide polymers. It can be used more species or two. Such a drying shrinkage reducing agent has the property of reducing the drying shrinkage of the cured mortar / concrete by reducing the stress generated when the moisture in the cured body such as mortar and concrete evaporates, More specifically, the surface tension is lowered by dissolving in water in the capillary gap that governs the shrinkage, and as a result, the capillary tension during drying is reduced to reduce the shrinkage. In particular, it is preferable that the drying shrinkage reducing agent comprises a compound represented by the following formula (1) as an active ingredient because the quality is stable when mixed with an expanding material and stored for a long period of time.
RO (AO) n H (1)
Wherein R is hydrogen, an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 5 to 6 carbon atoms, A is one or two alkylene groups having 2 to 3 carbon atoms, and n is 1 to 100. number)
本発明のセメント混和剤中の乾燥収縮低減剤の割合は、膨張材１００重量部に対して、乾燥収縮低減剤２〜３０重量部が最大膨張率が高く且つ乾燥収縮率が小さいので好ましい。より好ましくは５〜１０重量部とする。２重量部未満では充分な乾燥収縮低減効果が得られず最大膨張率からの収縮率が大きいため、乾燥収縮率が大きくなる。３０重量部を超えると、最大膨張率からの収縮量は小さいが、最大膨張率が小さいため乾燥収縮率が大きく、また硬化遅延を生じ易い。 The proportion of the drying shrinkage reducing agent in the cement admixture of the present invention is preferably 2 to 30 parts by weight of the drying shrinkage reducing agent with respect to 100 parts by weight of the expansion material because the maximum expansion rate is high and the drying shrinkage rate is small. More preferably, it is 5 to 10 parts by weight. If it is less than 2 parts by weight, a sufficient drying shrinkage reduction effect cannot be obtained, and the shrinkage rate from the maximum expansion rate is large, so that the drying shrinkage rate becomes large. If it exceeds 30 parts by weight, the amount of shrinkage from the maximum expansion rate is small, but since the maximum expansion rate is small, the drying shrinkage rate is large, and a curing delay is likely to occur.
本発明で使用するアルカリ金属塩としては、何れのものでも使用でき、例えば、アルミン酸塩、硫酸塩、及び炭酸塩が挙げられる。特に、本発明において配合する膨張材及び乾燥収縮低減剤との併用において、アルカリ金属炭酸塩及びアルカリ金属硫酸塩から選ばれる一種又は二種以上を使用することが最大膨張率が大きくなるので好ましく、この中でも炭酸ナトリウム又は／及び硫酸ナトリウムを使用することが、流動性のモルタルやコンクリートに本発明のセメント混和剤を用いたときに、流動性保持性が良好な点で好ましい。本発明において、アルカリ金属塩、特に、炭酸ナトリウムや硫酸ナトリウムを使用することで、セメントの水和反応を刺激し、膨張材と乾燥収縮低減剤を併用するときの硬化体の最大膨張率が大きく、硬化体の乾燥収縮率が小さく且つ硬化体のひび割れの発生が少ない。 Any alkali metal salt can be used in the present invention, and examples thereof include aluminate, sulfate, and carbonate. In particular, in combination with the expansion material and drying shrinkage reducing agent to be blended in the present invention, it is preferable to use one or more selected from alkali metal carbonates and alkali metal sulfates because the maximum expansion coefficient is increased, Among these, use of sodium carbonate and / or sodium sulfate is preferable in terms of good fluidity retention when the cement admixture of the present invention is used for fluid mortar or concrete. In the present invention, by using an alkali metal salt, particularly sodium carbonate or sodium sulfate, the hydration reaction of the cement is stimulated, and the maximum expansion coefficient of the cured product when the expansion agent and the drying shrinkage reducing agent are used in combination is large. The drying shrinkage rate of the cured body is small and the occurrence of cracks in the cured body is small.
本発明のセメント混和剤中のアルカリ金属塩各々の割合は、膨張材１００重量部に対して、アルカリ金属塩０．０１〜２．０重量部が好ましい。より好ましくは０．１〜１．０重量部とする。０．０１重量部未満では、最大膨張率が小さいため乾燥収縮率が大きく好ましくない。一方、２．０重量部を越えると、使用環境の温度変化による流動性の変動が大きくなり、安定した流動性を得ることが困難になる場合があり、また、流動性や軟度を維持する時間が短く、使用に適し難い。 The proportion of each alkali metal salt in the cement admixture of the present invention is preferably 0.01 to 2.0 parts by weight with respect to 100 parts by weight of the expansion material. More preferably, the content is 0.1 to 1.0 part by weight. If it is less than 0.01 parts by weight, the maximum expansion coefficient is small, so that the drying shrinkage is large, which is not preferable. On the other hand, if it exceeds 2.0 parts by weight, the fluctuation of the fluidity due to the temperature change of the use environment becomes large, it may be difficult to obtain a stable fluidity, and the fluidity and softness are maintained. Time is short and difficult to use.
本発明のセメント混和剤には、膨張材、乾燥収縮低減剤及びアルカリ金属塩以外に、本発明の効果を損なわない範囲でモルタルやコンクリートに使用できる混和材料を添加することができる。この混和材料としては、例えば高性能減水剤，高性能ＡＥ減水剤，ＡＥ減水剤及び流動化剤を含む減水剤、シリカフューム等のポゾラン、高炉スラグ等の潜在水硬性物質、急結剤、合成樹脂、保水剤、増粘剤、起泡剤、発泡剤、防錆剤、防凍剤、顔料、繊維、撥水剤、消泡剤、遅延剤、硬化促進剤等が挙げられる。 To the cement admixture of the present invention, an admixture that can be used for mortar and concrete can be added within the range not impairing the effects of the present invention, in addition to the expansion agent, the drying shrinkage reducing agent, and the alkali metal salt. Examples of the admixture include high-performance water-reducing agent, high-performance AE water-reducing agent, water-reducing agent containing AE water-reducing agent and superplasticizer, pozzolanes such as silica fume, latent hydraulic substances such as blast furnace slag, quick setting agent, synthetic resin , Water retention agents, thickeners, foaming agents, foaming agents, rust inhibitors, antifreeze agents, pigments, fibers, water repellents, antifoaming agents, retarders, curing accelerators and the like.
本発明のセメント混和剤の製造方法は、特に限定されない。例えば、ミキサで混合することにより製造する。また、本発明のセメント混和剤の使用方法は、特に限定されない。 The method for producing the cement admixture of the present invention is not particularly limited. For example, it manufactures by mixing with a mixer. Moreover, the usage method of the cement admixture of this invention is not specifically limited.
本発明のセメント組成物で使用するセメントは、水和反応により硬化する水硬性セメントであれば何れのものでも良く、例えば、普通，早強，超早強，低熱，中庸熱，白色などの各種ポルトランドセメント、エコセメント、並びにこれらポルトランドセメントまたはエコセメントにフライアッシュ，高炉スラグ，シリカフューム等を混合した各種混合セメント、アルミナセメント、カルシウムアルミネート・カルシウムナトリウムアルミネート・カルシウムサルホアルミネート等の急硬成分を主体とする急硬性セメント、超速硬セメント、ドロマイト、半水石膏等が例示でき、これらを単独で使用又は二種以上を併用できる。 The cement used in the cement composition of the present invention may be any hydraulic cement that hardens by a hydration reaction, for example, normal, early strength, ultra-early strength, low heat, moderate heat, white, etc. Portland cement, ecocement, and various hardened components such as various cements mixed with fly ash, blast furnace slag, silica fume, etc., alumina cement, calcium aluminate, calcium sodium aluminate, calcium sulfoaluminate, etc. Can be exemplified by quick-hardening cement, super-fast-hardening cement, dolomite, hemihydrate gypsum, etc., which can be used alone or in combination of two or more.
上記セメント混和剤の使用量は、セメント組成物１００重量部に対して、膨張材、乾燥収縮低減剤及びアルカリ金属塩の合計が０．３〜５．０重量部となる量とすることが好ましく、０．５〜２．０重量部となる量とすることがより好ましい。０．３重量部未満となる量では膨張率が不足する場合があり、５．０重量部となる量を超えると膨張率が過大になり、強度が低下する場合があるため好ましくない。 The amount of the cement admixture used is preferably such that the total amount of the expansion material, the drying shrinkage reducing agent, and the alkali metal salt is 0.3 to 5.0 parts by weight with respect to 100 parts by weight of the cement composition. More preferably, the amount is 0.5 to 2.0 parts by weight. If the amount is less than 0.3 parts by weight, the expansion rate may be insufficient. If the amount exceeds 5.0 parts by weight, the expansion rate may be excessive and the strength may be reduced.
本発明のセメント組成物には、セメントと上記セメント混和剤以外に、本発明の効果を損なわない範囲でモルタルやコンクリートに使用できる混和材料及び骨材を添加することができる。この混和材料としては、例えば高性能減水剤，高性能ＡＥ減水剤，ＡＥ減水剤及び流動化剤を含む減水剤、シリカフューム等のポゾラン、高炉スラグ等の潜在水硬性物質、急結剤、合成樹脂、保水剤、増粘剤、起泡剤、発泡剤、防錆剤、防凍剤、顔料、繊維、撥水剤、消泡剤、遅延剤、硬化促進剤等が挙げられ、これらを単独で使用又は二種以上を併用できる。また、骨材としては、例えば川砂、陸砂、海砂、砕砂、珪砂、川砂利、陸砂利、砕石、スラグ細骨材、再生細骨材及び人工骨材が挙げられ、これらを単独で使用又は二種以上を併用できる。 In addition to cement and the above-mentioned cement admixture, an admixture and an aggregate that can be used for mortar and concrete can be added to the cement composition of the present invention as long as the effects of the present invention are not impaired. Examples of the admixture include high-performance water-reducing agent, high-performance AE water-reducing agent, water-reducing agent containing AE water-reducing agent and superplasticizer, pozzolanes such as silica fume, latent hydraulic substances such as blast furnace slag, quick setting agent, synthetic resin , Water retention agents, thickeners, foaming agents, foaming agents, rust inhibitors, antifreeze agents, pigments, fibers, water repellents, antifoaming agents, retarders, curing accelerators, etc. Or two or more can be used in combination. Examples of aggregates include river sand, land sand, sea sand, crushed sand, quartz sand, river gravel, land gravel, crushed stone, slag fine aggregate, recycled fine aggregate, and artificial aggregate, and these are used alone. Or two or more can be used in combination.
本発明のセメント組成物の製造方法は、特に限定されない。例えば、各使用材料をミキサで混合すれば良い。また、本発明のセメント組成物の使用方法は、特に限定されない。通常は、混合容器内に本発明のセメント組成物及び水を投入、混合容器内でミキサにより混練することにより、セメントペースト、セメントモルタル又はセメントコンクリート等として用いる。グラウトミキサ、強制練りミキサ又は傾胴式ミキサ等のように、ミキサが混合容器を兼ねていても良い。混練時にセメント組成物中の各材料及び水を別々に混合容器に投入しても良いし、事前に一部又は全部をミキサで混合しておいても良い。混合する順序は特に限定されない。 The method for producing the cement composition of the present invention is not particularly limited. For example, each used material may be mixed with a mixer. Moreover, the usage method of the cement composition of this invention is not specifically limited. Usually, the cement composition of the present invention and water are put into a mixing container and kneaded with a mixer in the mixing container to be used as cement paste, cement mortar, cement concrete, or the like. The mixer may also serve as a mixing container, such as a grout mixer, a forced kneading mixer, or a tilted mixer. At the time of kneading, each material and water in the cement composition may be separately charged into a mixing container, or a part or all of them may be mixed in advance with a mixer. The order of mixing is not particularly limited.
本発明のセメント組成物をグラウトモルタルに用いる場合には、セメント１００重量部に対し、水３０〜６０重量部、砂５０〜３００重量部の配合とすることが好ましい。より好ましくは、砂８０〜２２０重量部とし、最も好ましくは砂１００〜２００重量部とする。砂の量がセメント１００重量部に対し３００重量部を超えると、グラウトモルタル中に含まれるセメントの量が少なくなるために、目標とする強度が得られなくなる場合があり、流動性を得難い。また、５０重量部未満では、硬化体の乾燥収縮率が大きく、またセメントの水和熱によるひび割れを生じ易い。 When using the cement composition of this invention for grout mortar, it is preferable to mix | blend 30-60 weight part of water and 50-300 weight part of sand with respect to 100 weight part of cement. More preferably, it is 80-220 weight part of sand, Most preferably, it is 100-200 weight part of sand. When the amount of sand exceeds 300 parts by weight with respect to 100 parts by weight of cement, the amount of cement contained in the grout mortar decreases, so that the target strength may not be obtained, and it is difficult to obtain fluidity. Moreover, if it is less than 50 weight part, the drying shrinkage rate of a hardening body is large, and it is easy to produce the crack by the heat of hydration of cement.
［実施例１］
以下に、本発明について実施例を挙げて更に詳しく説明する。
[Example 1]
Hereinafter, the present invention will be described in more detail with reference to examples.
膨張材、乾燥収縮低減剤及びアルカリ金属塩を混合して、表１に示す各配合のセメント混和剤を作製した。表１中の膨張材、乾燥収縮低減剤及びアルカリ金属塩の各配合量は、膨張材１００重量部に対する重量部である。普通ポルトランドセメント１００重量部、該セメント混和剤２重量部及び細骨材２００重量部を混合し、セメント組成物を作製した。更に、該セメント組成物中の普通ポルトランドセメント１００重量部に対して水３０重量部を加えてハンドミキサで混練してグラウトモルタルを作製した。作製した各グラウトモルタルの品質試験を実施し、最大膨張率及び長さ変化率を求め、ひび割れ抵抗性試験によるひび割れ発生の有無を調べた。その結果をセメント混和剤の配合とともに表１に示す。このときの使用材料及び品質試験の試験方法を、以下に示す。
＜使用材料＞
乾燥収縮低減剤：ｎ−ブチルアルコールのアルキレンオキシド付加物（プロピレンオキサイド（付加モル数２）及びエチレンオキサイド（付加モル数３））。
アルカリ金属塩Ａ：炭酸ナトリウム（市販品）。
アルカリ金属塩Ｂ：硫酸ナトリウム（市販品）。
アルカリ金属塩Ｃ：アルミン酸ナトリウム（市販品）。
普通ポルトランドセメント：太平洋セメント社製普通ポルトランドセメント。
細骨材：石灰石砕砂（比重２．６、粗粒率２．７０）。
膨張材：太平洋マテリアル株式会社製石灰系膨張材、商品名「太平洋エクスパン」、ＪＩＳ Ａ ６２０２「コンクリート用膨張材 」に適合。
水：水道水。
＜試験方法＞
膨張率：
ＪＩＳ Ａ ６２０２「コンクリート用膨張材」の付属書２（参考）「膨張コンクリートの拘束膨張及び収縮試験方法」に規定するＡ法に従ってグラウトモルタルの一軸拘束状態における膨張率を測定し、材齢７日までの最大値を求めた。全てのグラウトモルタルとも、材齢７日の膨張率は、材齢７日までの最大値であった。
長さ変化率：
ＪＩＳ Ａ １１２９−１「モルタル及びコンクリートの長さ変化試験方法−第一部：コンパレータ方法」に規定する試験方法に従って、作製したグラウトモルタルの長さ変化率を求めた。このとき、基長の測定は、グラウトモルタルの供試体を成型後１日湿空養生（温度２０±３℃、相対湿度９０％以上）し、脱型後７日間水中養生を行った直後に行った。基長の測定後、直ちに２０℃、相対湿度６０％の恒温室内に供試体を移し、２８日間保存した。２８日間保存後に測長し、このときの長さ変化率を算出した。長さ変化率の値は、全て負の値であったので、全て乾燥により収縮した。長さ変化率の絶対値が、ここでは乾燥収縮率であった。
ひび割れ抵抗性試験によるひび割れ発生の有無：
ＪＩＳ Ａ ６９０９「建築用仕上塗材」の「７．９ 初期乾燥によるひび割れ抵抗性試験」に準じ、２８日間風洞内（温度２０±３℃、相対湿度湿度６０％）に入れた試験体のひび割れの発生の有無を目視で調べた。試験体は、繊維強化セメント板（クラレ社製商品名「パワロンボード」、縦３００×横１５０×厚み５．５ｍｍ、平板）に断面正方形（１０×１０ｍｍ）の木製角材により作製した枠を貼り付け、この枠内（縦２８０×横１３０×深さ１０ｍｍ）にグラウトモルタルを塗り付け１日湿空養生（温度２０±３℃、相対湿度９０％以上）したものを用いた。
The expansion agent, the drying shrinkage reducing agent, and the alkali metal salt were mixed to prepare cement admixtures with various formulations shown in Table 1. Each compounding quantity of the expansion | swelling material in Table 1, a drying shrinkage reducing agent, and an alkali metal salt is a weight part with respect to 100 weight part of expansion | swelling materials. A cement composition was prepared by mixing 100 parts by weight of ordinary Portland cement, 2 parts by weight of the cement admixture and 200 parts by weight of fine aggregate. Further, 30 parts by weight of water was added to 100 parts by weight of ordinary Portland cement in the cement composition and kneaded with a hand mixer to prepare grout mortar. A quality test was conducted on each of the produced grout mortars, the maximum expansion rate and the rate of change in length were obtained, and the presence or absence of cracks was examined by a crack resistance test. The results are shown in Table 1 together with the cement admixture. The materials used at this time and the test method of the quality test are shown below.
<Materials used>
Drying shrinkage reducing agent: alkylene oxide adduct of n-butyl alcohol (propylene oxide (added mole number 2) and ethylene oxide (added mole number 3)).
Alkali metal salt A: Sodium carbonate (commercially available).
Alkali metal salt B: Sodium sulfate (commercially available product).
Alkali metal salt C: sodium aluminate (commercially available product).
Ordinary Portland cement: Ordinary Portland cement manufactured by Taiheiyo Cement.
Fine aggregate: Limestone crushed sand (specific gravity 2.6, coarse particle ratio 2.70).
Expansion material: Compliant with Taiheiyo Material Co., Ltd. lime-based expansion material, trade name “Pacific Expan”, JIS A 6202 “Concrete Expansion Material”.
Water: tap water.
<Test method>
Expansion rate:
Measure the expansion rate in uniaxial restraint state of grout mortar according to A method specified in Annex 2 (Reference) “Constrained Expansion and Shrinkage Test Method of Expanded Concrete” of JIS A 6202 “Expanding Material for Concrete”, age 7 days The maximum value up to was obtained. In all the grout mortars, the expansion rate at 7 days of age was the maximum value until 7 days of age.
Length change rate:
According to the test method prescribed | regulated to JISA1129-1 "Mortar and concrete length change test method-1st part: Comparator method", the length change rate of the produced grout mortar was calculated | required. At this time, the measurement of the base length is carried out immediately after the grout mortar specimen is molded after wet molding (temperature 20 ± 3 ° C., relative humidity 90% or more), and after demolding, underwater curing for 7 days. It was. Immediately after the measurement of the base length, the specimen was transferred into a constant temperature room at 20 ° C. and a relative humidity of 60%, and stored for 28 days. The length was measured after storage for 28 days, and the length change rate at this time was calculated. Since the values of the rate of change in length were all negative values, they all shrunk by drying. The absolute value of the rate of change in length is here the drying shrinkage.
Presence or absence of cracking by crack resistance test:
In accordance with JIS A 6909 “Finish Finishing Coating Material”, “7.9 Crack Resistance Test by Initial Drying”, cracks in the test specimen placed in the wind tunnel (temperature 20 ± 3 ° C., relative humidity and humidity 60%) for 28 days The presence or absence of occurrence was visually examined. The test body is a fiber reinforced cement board (trade name “Powerlon Board” manufactured by Kuraray Co., Ltd., length 300 × width 150 × thickness 5.5 mm, flat plate) with a frame made of wooden square material having a square cross section (10 × 10 mm), In this frame (vertical 280 × width 130 × depth 10 mm), grout mortar was applied, and one day wet air curing (temperature 20 ± 3 ° C., relative humidity 90% or more) was used.
本発明のセメント混和剤を使用した全てのグラウトモルタルは、材齢７日までの最大膨張率即ち材齢７日における膨張率が１５０〜２５０×１０−６の範囲、且つ長さ変化率が−１５０×１０−６以下の物性を有し、ひび割れの発生を抑制できることが確認された。本発明のセメント混和剤を使用した全てのグラウトモルタルは、材齢７日における膨張率が１５０〜２５０×１０−６の範囲であるので、土木学会コンクリート標準示方書「膨張コンクリート設計施工指針」に示されている収縮補償用コンクリートに適合するので、膨張性状が良好であった。参考品１は、最大膨張率は大きいが、長さ変化率が−４０３×１０−６と大きく収縮している。また、参考品１は、ひび割れ抵抗性試験においてひび割れが発生した。また、参考品２〜４は、乾燥収縮低減剤の含有量が増えるに従い乾燥収縮が抑制されているが、最大膨張率が小さくなり、ひび割れが発生した。
All the grout mortars using the cement admixture of the present invention have a maximum expansion rate of up to 7 days of material, that is, an expansion rate of 150 to 250 × 10 −6 at a material age of 7 days, and a length change rate of − It was confirmed that it has physical properties of 150 × 10 −6 or less and can suppress the occurrence of cracks. Since all grout mortars using the cement admixture of the present invention have an expansion rate in the range of 150 to 250 × 10 −6 at the age of 7 days, the Japan Society of Civil Engineers Concrete Standard Specification “Expanded Concrete Design and Construction Guidelines” Since it is compatible with the shrinkage-compensating concrete shown, the expansion property was good. Although the
本発明の本発明のセメント混和剤及びセメント組成物は、セメントモルタルやセメントコンクリート等の硬化体の乾燥収縮率が小さく且つひび割れの発生が少ないので、鉄筋コンクリート、鉄骨鉄筋コンクリート、充填モルタル、セルフレベリング材、壁・床・柱・梁等の補修用又は補強用モルタル等に好適に用いることができる。特に、ボックスカルバートやコンクリート製矢板等のように膨張材によるケミカルプレストレスを導入し且つ乾燥収縮ひび割れを抑制したいコンクリート二次製品、壁、屋根及び床等のように単位体積当りの表面積の大きな部位の構築に好適に用いることができる。本発明のセメント混和剤又はセメント組成物を用いた構造物は、乾燥収縮率が小さく且つひび割れの発生が少ないので、高耐久性の構造物となる。 The cement admixture and the cement composition of the present invention have a low drying shrinkage rate and less cracking of hardened bodies such as cement mortar and cement concrete, so reinforced concrete, steel reinforced concrete, filled mortar, self-leveling material, It can be suitably used for repairing or reinforcing mortar for walls, floors, columns, beams and the like. In particular, parts that have a large surface area per unit volume, such as concrete secondary products, walls, roofs, and floors that require chemical prestress due to expansion material such as box culverts and concrete sheet piles, and that want to suppress dry shrinkage cracks It can use suitably for construction of. Since the structure using the cement admixture or cement composition of the present invention has a low drying shrinkage rate and little occurrence of cracks, it becomes a highly durable structure.
１ 膨張材を単独で使用する場合
２ 乾燥収縮低減剤を単独で使用する場合
３ 膨張材と乾燥収縮低減剤を単に併用する場合
４ 本発明のセメント混和剤を使用する場合
1 When using an expansion material alone 2 When using a drying shrinkage reducing agent alone 3 When simply using an expansion material and a drying
Claims (4)
ＲＯ（ＡＯ） ｎ Ｈ （１）
（式中、Ｒは水素、炭素数１〜６のアルキル基又は炭素数５〜６のシクロアルキル基、Ａは炭素数２〜３の１種または２種のアルキレン基、ｎは１〜１００の数） It contains an expanding material, a drying shrinkage reducing agent and an alkali metal salt . The drying shrinkage reducing agent is 2 to 30 parts by weight and the alkali metal salt is 0.01 to 2.0 parts by weight with respect to 100 parts by weight of the expanding material. The expansion material is a lime-based expansion material or ettringite-based expansion material that conforms to JIS A 6202 “Expansion material for concrete”, and the drying shrinkage reducing agent comprises a compound represented by the following formula (1) as an active ingredient. There, the alkali metal salt is an alkali metal aluminate, one or two or more der Ru cement admixture selected from alkali metal carbonates and alkali metal sulfates.
RO (AO) n H (1)
Wherein R is hydrogen, an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 5 to 6 carbon atoms, A is one or two alkylene groups having 2 to 3 carbon atoms, and n is 1 to 100. number)
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