JP6180946B2 - Concrete composition - Google Patents
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- JP6180946B2 JP6180946B2 JP2014007212A JP2014007212A JP6180946B2 JP 6180946 B2 JP6180946 B2 JP 6180946B2 JP 2014007212 A JP2014007212 A JP 2014007212A JP 2014007212 A JP2014007212 A JP 2014007212A JP 6180946 B2 JP6180946 B2 JP 6180946B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description
本発明は、コンクリート組成物に関する。 The present invention relates to a concrete composition.
高強度コンクリートは、結合材に対する水の重量比（水結合材比）を低くして、硬化後のコンクリート組織を緻密にすることで圧縮強度を高めたものである。 High-strength concrete is obtained by increasing the compressive strength by reducing the weight ratio of water to the binder (water binder ratio) and densifying the concrete structure after hardening.
水結合材比が低い高強度コンクリートは、一般的に硬化時の自己収縮が大きくなる傾向にある。自己収縮が大きいと、ひびわれ発生の原因になるため、自己収縮の低減化を図る高強度コンクリートが開発されている。 High-strength concrete having a low water binder ratio generally tends to increase self-shrinkage when cured. High self-contraction causes cracking, so high-strength concrete has been developed to reduce self-contraction.
例えば、特許文献１には、設計基準強度が１００Ｎ／ｍｍ２を超える高強度コンクリートの配合において、粗骨材の３０容積％以下を人工軽量粗骨材に置換し、コンクリート１ｍ３当たり３０ｋｇ以下の膨張材を添加してなる高強度コンクリートが開示されている。
なお、人工軽量粗骨材には、吸水率が５〜２０％、圧壊荷重１０００〜２０００Ｎ、絶乾密度が１．４〜２．０ｇ／ｃｍ３のものが使用されている。
For example, in Patent Document 1, in the blending of high-strength concrete having a design standard strength exceeding 100 N / mm 2 , 30% by volume or less of the coarse aggregate is replaced with artificial lightweight coarse aggregate, and 30 kg or less per 1 m 3 of concrete. A high-strength concrete obtained by adding an expansion material is disclosed.
As the artificial lightweight coarse aggregate, those having a water absorption rate of 5 to 20%, a crushing load of 1000 to 2000 N, and an absolutely dry density of 1.4 to 2.0 g / cm 3 are used.
また、特許文献２には、４００〜６００ｋｇ／ｍ３のセメントを含む結合材と、１０ｗｔ％以上の水を含有させた２８０〜４００Ｌ／ｍ３の人工軽量粗骨材と、１５０〜１８５ｋｇ／ｍ３の水とを含有するコンクリートが開示されている。 Patent Document 2 discloses a binder containing 400 to 600 kg / m 3 of cement, 280 to 400 L / m 3 of artificial lightweight coarse aggregate containing 10 wt% or more of water, and 150 to 185 kg / m. Concrete containing 3 waters is disclosed.
特許文献１および特許文献２に記載のコンクリートは、粗骨材の一部に人工軽量粗骨材を採用することで、人工軽量粗骨材が保有する水分によりコンクリートの自己収縮や乾燥収縮の低減化を図っている。 The concrete described in Patent Document 1 and Patent Document 2 employs an artificial lightweight coarse aggregate as part of the coarse aggregate, thereby reducing the self-shrinkage and drying shrinkage of the concrete due to the moisture held by the artificial lightweight coarse aggregate. We are trying to make it.
ところが、人工軽量粗骨材を使用すると、人工軽量粗骨材を使用しない通常のコンクリートに比べて、圧縮強度が大きく低下する虞がある。
特許文献１では硬質な石炭灰系の人工軽量粗骨材を使用することで所望の圧縮強度を確保しているが、このような人工軽量粗骨材は入手が難しく、高価であった。
However, when an artificial lightweight coarse aggregate is used, the compressive strength may be greatly reduced as compared to ordinary concrete not using an artificial lightweight coarse aggregate.
In Patent Document 1, a desired coal strength is ensured by using a hard coal ash-based artificial lightweight coarse aggregate, but such an artificial lightweight coarse aggregate is difficult to obtain and expensive.
本発明は、圧縮強度が１２０Ｎ／ｍｍ２以上でありながら硬化時の自己収縮が小さいコンクリート組成物を提供することを課題とする。 An object of the present invention is to provide a concrete composition having a compressive strength of 120 N / mm 2 or more and a small self-shrinkage during curing.
前記課題を解決するために、本発明のコンクリート組成物は、少なくともセメントとシリカフュームとを含む結合材と、前記結合材に対する重量比が１０〜２０％となるように添加された１４５〜１５５ｋｇ／ｍ３の水と、絶対容積が２７０〜３３０Ｌ／ｍ３の粗骨材と、絶対容積が８８〜１６８Ｌ／ｍ３の人工軽量細骨材とを含有することを特徴としている。 In order to solve the above-mentioned problems, the concrete composition of the present invention includes a binder containing at least cement and silica fume and 145 to 155 kg / m added so that the weight ratio to the binder is 10 to 20%. 3 of water, absolute volume is characterized as coarse aggregate 270~330L / m 3, that the absolute volume contains a lightweight fine aggregate 88~168L / m 3.
かかるコンクリート組成物によれば、自己収縮の低減化を図りながらも優れた強度発現性を有したコンクリート製品を提供することが可能となる。
なお、単位水量が１５５ｋｇ／ｍ３を上回ると、強度を維持するために単位セメント量を増やす必要があり、自己収縮を増大させるおそれがある。一方、単位水量が１４５ｋｇ／ｍ３を下回るとフレッシュコンクリートの流動性が悪化し、施工性が低下する。また、単位粗骨材量が絶対容積で３３０Ｌ／ｍ３を上回るとフレッシュコンクリートの鉄筋間隙通過性が悪化し、施工性が低下する。一方、単位粗骨材量が絶対容積で２７０Ｌ／ｍ３を下回ると、単位水量および単位結合材量を増やすことになり、自己収縮を増大させるおそれがある。
According to such a concrete composition, it is possible to provide a concrete product having excellent strength development while reducing self-shrinkage.
If the unit water amount exceeds 155 kg / m 3 , it is necessary to increase the unit cement amount in order to maintain the strength, which may increase self-shrinkage. On the other hand, if the unit water amount is less than 145 kg / m 3 , the fluidity of fresh concrete deteriorates and the workability decreases. On the other hand, if the unit coarse aggregate amount exceeds 330 L / m 3 in terms of absolute volume, the rebar gap passing property of fresh concrete deteriorates and the workability deteriorates. On the other hand, when the unit coarse aggregate amount is less than 270 L / m 3 in absolute volume, the unit water amount and the unit binder amount are increased, which may increase self-shrinkage.
なお、前記粗骨材の絶対容積が２９０〜３１０Ｌ／ｍ３であれば、結合材量の増加（自己収縮量の増加）を抑えつつ良好な施工性を確保することができる。
さらに、細骨材の絶対容積が２７０〜２９０Ｌ／ｍ３である場合には、前記細骨材のうちの１３０〜１５０Ｌ／ｍ３を前記人工軽量細骨材に置換するとよい。すなわち、前記人工軽量細骨材の絶対容積が１３０〜１５０Ｌ／ｍ３であり、前記人工軽量細骨材の絶対容積と前記人工軽量細骨材以外の細骨材の絶対容積の合計が２７０〜２９０Ｌ／ｍ３であれば、材齢２００日におけるひずみが膨張側となるか、あるいは、収縮側となった場合でもゼロに近い値となる。
In addition, if the absolute volume of the coarse aggregate is 290 to 310 L / m 3 , good workability can be ensured while suppressing an increase in the amount of binder (increase in self-shrinkage amount).
Further, if the absolute volume of fine aggregate is 270~290L / m 3 is the 130~150L / m 3 of the fine aggregates may be replaced with the artificial lightweight fine aggregates. That is, the absolute volume of the artificial lightweight fine aggregate is 130 to 150 L / m 3 , and the total of the absolute volume of the artificial lightweight fine aggregate and the absolute volume of the fine aggregate other than the artificial lightweight fine aggregate is 270 to If it is 290 L / m 3 , the strain at the age of 200 days will be a value close to zero even when the strain is on the expansion side or the contraction side.
前記結合材が、スラグせっこう系混和材を含んでおり、前記セメントが普通ポルトランドセメントである場合には、前記普通ポルトランドセメント、前記スラグせっこう系混和材および前記シリカフュームの合計重量を１００としたとき、前記普通ポルトランドセメントの重量を６８〜７２、前記スラグせっこう系混和材の重量を１８〜２２、前記シリカフュームの重量を８〜１２とするとよい。このような結合材は、強度の発現が早いという長所がある一方、自己収縮が大きいという短所を有しているが、本発明で規定した粗骨材と人工軽量細骨材を採用すれば、当該短所を改善することができる。 When the binder contains a slag gypsum admixture and the cement is ordinary portland cement, the total weight of the ordinary portland cement, the slag gypsum admixture and the silica fume is 100. The normal Portland cement may have a weight of 68 to 72, the slag gypsum-based admixture may have a weight of 18 to 22, and the silica fume may have a weight of 8 to 12. Such a binding material has the advantage of rapid strength development, but has the disadvantage of large self-shrinkage, but if the coarse aggregate and artificial lightweight fine aggregate defined in the present invention are adopted, This disadvantage can be improved.
本発明のコンクリート組成物によれば、圧縮強度が１２０Ｎ／ｍｍ２以上でありながら硬化時の自己収縮が小さい高品質なコンクリート製品を製造することが可能となる。 According to the concrete composition of the present invention, it is possible to produce a high-quality concrete product having a compressive strength of 120 N / mm 2 or more and small self-shrinkage during curing.
本実施形態のコンクリート組成物は、結合材と、水と、粗骨材と、細骨材と、を含むものであり、細骨材の一部が人工軽量細骨材に置換されている。収縮低減剤および膨張剤は含まれていない。
本実施形態では、コンクリート組成物を封緘養生する。
The concrete composition of the present embodiment includes a binder, water, coarse aggregate, and fine aggregate, and a part of the fine aggregate is replaced with artificial lightweight fine aggregate. Shrinkage reducing agents and swelling agents are not included.
In the present embodiment, the concrete composition is sealed and cured.
結合材は、ポルトランドセメントとスラグせっこう系混和材とシリカフュームとを含んでいる。結合材は、予め所定の配合で混合されたプレミックス品を使用してもよいし、コンクリート製造時に混合してもよい。
なお、結合材は、少なくともセメントとシリカフュームとを含む超高強度コンクリート用セメントであれば限定されるものではない。
The binder contains Portland cement, slag gypsum based admixture and silica fume. As the binder, a premixed product previously mixed in a predetermined composition may be used, or may be mixed during concrete production.
The binder is not limited as long as it is a cement for ultra high strength concrete containing at least cement and silica fume.
本実施形態では、結合材として、普通ポルトランドセメントとスラグせっこう系混和材とシリカフュームを含む超高強度コンクリート用セメントであって、密度が２．９９ｇ／ｃｍ３で、普通ポルトランドセメントとスラグせっこう系混和材とシリカフュームが重量比で概ね７０：２０：１０となるように配合された超高強度コンクリート用セメント（例えば、株式会社デイ・シイ社製ＶＫＣ１００ＳＦ）を使用する。なお、普通ポルトランドセメントの混合比率は、前記３成分の合計重量を１００としたときに、７０±２（６８〜７２）であればよく、同様に、スラグせっこう系混和材の混合比率は２０±２（１８〜２２）、シリカフュームの混合比率は１０±２（８〜１２）であればよい。
このような組成の超高強度コンクリート用セメントは、超高強度用（又は高強度用）コンクリートとして通常使用されるセメント（例えば、低熱ポルトランドセメント又は中庸熱ポルトランドセメントにシリカフュームを添過したセメント）と比較すると、強度の発現が早いという長所がある一方、自己収縮が大きいという短所を有している。また、粗骨材が多くなると、収縮は小さくなるが強度は低下する傾向がある。本実施形態では、粗骨材と人工軽量細骨材を後述の配合量としているが、かかる配合量を採用すれば、普通ポルトランドセメントとスラグせっこう系混和材とシリカフュームとを含む超高強度コンクリート用セメントの短所を改善することができる。
In this embodiment, a cement for ultra-high strength concrete containing ordinary Portland cement, slag gypsum admixture and silica fume as a binder, the density is 2.99 g / cm 3 , and ordinary Portland cement and slag gypsum. A cement for ultra-high strength concrete (for example, VKC100SF manufactured by Daishi Co., Ltd.) in which the system admixture and silica fume are mixed at a weight ratio of approximately 70:20:10 is used. The mixing ratio of ordinary Portland cement may be 70 ± 2 (68 to 72) when the total weight of the three components is 100. Similarly, the mixing ratio of the slag / gypsum admixture is 20 The mixing ratio of ± 2 (18-22) and silica fume may be 10 ± 2 (8-12).
The cement for ultra-high-strength concrete having such a composition is a cement that is usually used as ultra-high-strength (or high-strength) concrete (for example, low-heat Portland cement or medium-heat Portland cement added with silica fume). In comparison, it has the advantage of rapid onset of strength, but has the disadvantage of large self-contraction. Moreover, when coarse aggregate increases, the shrinkage decreases, but the strength tends to decrease. In this embodiment, coarse aggregates and artificial lightweight fine aggregates are used in the following blending amounts. If such blending amounts are employed, ultra high strength concrete containing ordinary Portland cement, slag gypsum-based admixture, and silica fume. The disadvantages of cement can be improved.
水は、結合材に対する重量比が１０〜２０％、より好ましくは１５〜２０％となるように添加する。
なお、水結合材比が２０％を超えると圧縮強度１２０Ｎ／ｍｍ２以上を得るのは困難になり、１０％を下回ると練り混ぜが困難になる。
Water is added so that the weight ratio to the binder is 10 to 20%, more preferably 15 to 20%.
If the water binder ratio exceeds 20%, it becomes difficult to obtain a compressive strength of 120 N / mm 2 or more, and if it is less than 10%, kneading becomes difficult.
また、コンクリート組成物の単位水量が１５５ｋｇ／ｍ３を超えると、強度を維持するために結合材量を増加させる必要が生じる。結合材の量を増加させると、自己収縮が増大するおそれがある。 Moreover, when the unit water amount of a concrete composition exceeds 155 kg / m < 3 >, in order to maintain intensity | strength, it will be necessary to increase the amount of binders. Increasing the amount of binder may increase self-shrinkage.
一方、単位水量が１４５ｋｇ／ｍ３を下回ると、フレッシュコンクリートの流動性が悪化し、施工性が低下してしまう。
したがって、コンクリート組成物に添加する水の量は、１４５〜１５５ｋｇ／ｍ３とする。
On the other hand, if the unit water amount is less than 145 kg / m 3 , the fluidity of fresh concrete deteriorates and the workability deteriorates.
Therefore, the amount of water added to the concrete composition is 145 to 155 kg / m 3 .
粗骨材には、天然の砂利または砕石を使用する。なお、粗骨材を構成する材料は限定されない。本実施形態では、コンクリート組成物に対して、安山岩系砕石（表乾密度２．６０ｇ／ｃｍ３、吸水率２．７８％、最大粒径２０ｍｍ）からなり絶対容積が２７０〜３３０Ｌ／ｍ３の天然粗骨材（普通粗骨材）を添加する。
For the coarse aggregate, natural gravel or crushed stone is used. In addition, the material which comprises a coarse aggregate is not limited. In the present embodiment, the concrete composition is composed of andesite-based crushed stone (surface dry density 2.60 g / cm 3 , water absorption 2.78%,
ここで、粗骨材の絶対容積が３３０Ｌ／ｍ３を超えるとフレッシュコンクリートの鉄筋間隙通過性を悪化させて、施工性が低下するおそれがある。
一方、粗骨材の絶対容積が２７０Ｌ／ｍ３を下回ると結合材および水の量を増加させる必要が生じる。結合材量を増加させると自己収縮が増大するおそれがある。
なお、粗骨材の絶対容積が２９０〜３１０Ｌ／ｍ３であれば、結合材量および水の増加を抑えつつ良好な施工性を確保することができる。
Here, if the absolute volume of the coarse aggregate exceeds 330 L / m 3 , the rebar gap passing property of fresh concrete is deteriorated, and the workability may be lowered.
On the other hand, if the absolute volume of the coarse aggregate is less than 270 L / m 3 , it is necessary to increase the amount of the binder and water. Increasing the amount of binder may increase self-shrinkage.
In addition, if the absolute volume of the coarse aggregate is 290 to 310 L / m 3 , good workability can be ensured while suppressing an increase in the amount of binder and water.
本実施形態では、細骨材として安山岩系砕砂（表乾密度２．６２ｇ／ｃｍ３、吸水率２．８８％、粗粒率２．７２、微粒分量５．４％）を使用する。細骨材を構成する材料は、例えば、川砂、山砂等の天然細骨材（普通細骨材）のほか、高炉スラグ細骨材等も採用可能である。 In the present embodiment, andesite-based crushed sand (surface dry density 2.62 g / cm 3 , water absorption 2.88%, coarse particle rate 2.72, fine particle amount 5.4%) is used as the fine aggregate. As the material constituting the fine aggregate, for example, natural fine aggregate (ordinary fine aggregate) such as river sand and mountain sand, blast furnace slag fine aggregate and the like can be adopted.
人工軽量細骨材には、ＪＩＳ Ａ ５００２（構造用軽量コンクリート骨材）に規定される「人工軽量細骨材ＭＡ−４１７」を使用する。本実施形態で用いた人工軽量細骨材は、膨張性頁岩を粉砕・焼成して製造する汎用品で、表乾密度１．８８ｇ／ｃｍ３、吸水率１４．０％、粗粒率２．７６、微粒分量６．７％であり、表層に溶融ガラス質のシェルを有する全空隙率３０ｖｏｌ％程度の多孔質材料である。 As the artificial lightweight fine aggregate, “artificial lightweight fine aggregate MA-417” defined in JIS A 5002 (lightweight concrete aggregate for structure) is used. The artificial lightweight fine aggregate used in this embodiment is a general-purpose product produced by pulverizing and firing expansive shale, with a surface dry density of 1.88 g / cm 3 , a water absorption of 14.0%, and a coarse particle ratio of 2. 76, a porous material with a fine particle content of 6.7% and a total porosity of about 30 vol% having a molten glassy shell on the surface layer.
細骨材の量が多いと、強度が低下し、コンクリートの自己収縮が大きくなる傾向にある。そのため、本実施形態では、細骨材の一部を人工軽量細骨材に置換することで、人工軽量細骨材が含有する水分によりコンクリートの自己収縮の抑制を図っている。なお、置換前の細骨材の絶対容積（すなわち、人工軽量細骨材の絶対容積と人工軽量細骨材以外の細骨材の絶対容積の合計）は、３３６Ｌ／ｍ３とする。 If the amount of fine aggregate is large, the strength tends to decrease and the self-shrinkage of the concrete tends to increase. Therefore, in this embodiment, the self-shrinkage of the concrete is suppressed by the moisture contained in the artificial lightweight fine aggregate by replacing a part of the fine aggregate with the artificial lightweight fine aggregate. The absolute volume of the fine aggregate before replacement (that is, the sum of the absolute volume of the artificial lightweight fine aggregate and the absolute volume of the fine aggregate other than the artificial lightweight fine aggregate) is 336 L / m 3 .
なお、図３は、人工軽量細骨材の使用量と自己収縮ひずみの関係を示すグラフである。図中のプロットは、後記する表１のコンクリート組成物の硬化体（材齢２８日、９１日、１８２日）で実測した自己収縮ひずみである。図中に記載した回帰式によれば、コンクリート組成物に対する人工軽量細骨材の単位数量は、自己収縮又は膨張による長さの変化を±２００×１０−６に収める場合には１６５〜３１５ｋｇ／ｍ３（絶対容積に換算すると８８〜１６８Ｌ／ｍ３）とし、自己収縮又は膨張による長さの変化を±１００×１０−６に収める場合には２００〜２７０ｋｇ／ｍ３（絶対容積に換算すると１０６〜１４３Ｌ／ｍ３）とする。
In addition, FIG. 3 is a graph which shows the relationship between the usage-amount of an artificial lightweight fine aggregate, and a self contraction distortion. The plots in the figure are self-shrinkage strains measured on the hardened concrete compositions (
本実施形態のコンクリート組成物によれば、自己収縮の低減化を図りながらも優れた強度発現性を有したコンクリート製品を提供することが可能となる。
つまり、硬化時の自己収縮が小さく、かつ、圧縮強度が１２０Ｎ／ｍｍ２以上（設計基準強度１００Ｎ／ｍｍ２）のコンクリート組成物を提供することができる。これは、細骨材の一部として人工軽量細骨材を採用することで、人工軽量細骨材が有する細孔に含有されている水分がコンクリートの硬化時の自己収縮の軽減に寄与するためである。このように、人工軽量細骨材を採用すると、水結合材比が小さい場合であっても、自己収縮を小さくすることができる。
According to the concrete composition of the present embodiment, it is possible to provide a concrete product having excellent strength development while reducing self-shrinkage.
That is, it is possible to provide a concrete composition having a small self-shrinkage during curing and a compressive strength of 120 N / mm 2 or more (design standard strength 100 N / mm 2 ). This is because by using artificial lightweight fine aggregate as part of the fine aggregate, the moisture contained in the pores of the artificial lightweight fine aggregate contributes to the reduction of self-shrinkage when concrete hardens It is. As described above, when the artificial lightweight fine aggregate is employed, the self-shrinkage can be reduced even when the water binder ratio is small.
また、水、結合材、粗骨材および人工軽量細骨材の単位量を適切に配合することにより、細骨材を人工軽量細骨材に置き換えることによる強度低下を最小限に抑制している。人工軽量細骨材が有する細孔に含有されている水分は、セメントペースト部分の水和反応にも寄与する。 In addition, by properly blending unit quantities of water, binder, coarse aggregate and artificial lightweight fine aggregate, strength reduction due to replacement of fine aggregate with artificial lightweight fine aggregate is minimized. . The moisture contained in the pores of the artificial lightweight fine aggregate also contributes to the hydration reaction of the cement paste portion.
細骨材の全てを人工軽量細骨材に置換すると、人工軽量細骨材からの水の供給によってセメントペースト部分の強度は増大するが、人工軽量細骨材による空隙量（欠陥）の増加が大きいため、コンクリートとしての強度が低下する。一方、細骨材の半分を人工軽量細骨材に置換すると、セメントペースト部分の強度の増大と、空隙量の増加が相殺し、コンクリートとしての強度低下を抑えることができる。人工軽量粗骨材の場合は、コンクリート中に分散して配置される人工軽量細骨材に比べて、空隙欠陥の集中と水分供給の非効率さによって、強度低下が大きくなると考えられる。 When all the fine aggregates are replaced with artificial lightweight fine aggregates, the strength of the cement paste increases due to the supply of water from the artificial lightweight fine aggregates, but the amount of voids (defects) due to the artificial lightweight fine aggregates increases. Since it is large, the strength as concrete decreases. On the other hand, when half of the fine aggregate is replaced with the artificial lightweight fine aggregate, the increase in the strength of the cement paste portion and the increase in the amount of voids cancel each other, and the decrease in strength as concrete can be suppressed. In the case of the artificial lightweight coarse aggregate, it is considered that the strength reduction is increased due to the concentration of void defects and the inefficiency of water supply compared to the artificial lightweight fine aggregate dispersed and arranged in the concrete.
本実施形態では、細骨材の一部を人工軽量細骨材に置換しているが、天然細骨材と人工軽量細骨材の粗粒率および微粒分量をほぼ等しくしたので、フレッシュコンクリートの性状（スランプフローなど）は、人工軽量細骨材を使用しない場合と大きな違いはない。なお、細骨材の全部を人工軽量細骨材に置換した場合でも、天然細骨材と人工軽量細骨材の粗粒率および微粒分量をほぼ等しくしておけば、フレッシュコンクリートの性状（スランプフローなど）への影響を小さくすることができる。 In this embodiment, a part of the fine aggregate is replaced with the artificial lightweight fine aggregate, but since the coarse grain ratio and the amount of fine particles of the natural fine aggregate and the artificial lightweight fine aggregate are substantially equal, The properties (such as slump flow) are not significantly different from those when no artificial lightweight fine aggregate is used. Even if all of the fine aggregates are replaced with artificial lightweight fine aggregates, the properties of fresh concrete (slump) can be achieved if the coarse particles ratio and the amount of fine particles of natural fine aggregates and artificial lightweight fine aggregates are approximately equal. The influence on the flow etc.) can be reduced.
次に、本実施形態のコンクリート組成物について、圧縮強度試験を行った結果を示す。
本試験では、水結合材比が２０％と１５％のコンクリート組成物について、細骨材の絶対容積の０％、５０％、１００％を人工軽量細骨材量に置き換えて、圧縮強度試験を行った。
Next, the result of having performed the compressive strength test about the concrete composition of this embodiment is shown.
In this test, compressive strength tests were conducted on concrete compositions with water binder ratios of 20% and 15%, replacing 0%, 50% and 100% of the absolute volume of fine aggregate with the amount of artificial lightweight fine aggregate. went.
コンクリート組成物の調合を表１に示す。
表１に示す調合のコンクリート組成物について、水中養生と封緘養生を行い、それぞれ圧縮強度試験を行った。圧縮強度試験の結果を図１に示す。なお、粗骨材の表乾密度は２．６０ｇ／ｃｍ３であるので、粗骨材の単位量７８０ｋｇ／ｍ３を絶対容積に換算すると、３００Ｌ／ｍ３（＝７８０／２．６０）となる。また、人工軽量細骨材の表乾密度は１．８８ｇ／ｃｍ３であるので、例えば人工軽量細骨材の単位量２６２ｋｇ／ｍ３を絶対容積に換算すると、１３９Ｌ／ｍ３（＝２６２／１．８８）となる。
The composition of the concrete composition is shown in Table 1.
About the concrete composition of the mixing | blending shown in Table 1, underwater curing and sealing curing were performed, and the compressive strength test was each performed. The results of the compressive strength test are shown in FIG. In addition, since the surface dry density of the coarse aggregate is 2.60 g / cm 3 , the unit amount of 780 kg / m 3 of the coarse aggregate is converted to an absolute volume of 300 L / m 3 (= 780 / 2.60). Become. Moreover, since the surface dry density of the artificial lightweight fine aggregate is 1.88 g / cm 3 , for example, when the unit amount 262 kg / m 3 of the artificial lightweight fine aggregate is converted into an absolute volume, 139 L / m 3 (= 262 / 1.88).
図１に示すように、本実施形態のコンクリート組成物によれば、水結合材比を２０％として細骨材の絶対容積の５０％を人工軽量細骨材に置き換えた場合には、圧縮強度が１３０Ｎ／ｍｍ２以上となった。特に、封緘養生であれば、人工軽量細骨材を採用することによる圧縮強度の低下を３％以下とすることができる。 As shown in FIG. 1, according to the concrete composition of the present embodiment, when the water binder ratio is 20% and 50% of the absolute volume of the fine aggregate is replaced with the artificial lightweight fine aggregate, the compressive strength Was 130 N / mm 2 or more. In particular, in the case of sealing, the reduction in compressive strength due to the use of artificial lightweight fine aggregate can be reduced to 3% or less.
また、水結合材比を１５％として細骨材の５０％を人工軽量細骨材に置き換えた場合には、水中養生と封緘養生とがいずれも人工軽量細骨材を使用しない場合と同等の強度が発現された。 In addition, when the water binder ratio is 15% and 50% of the fine aggregate is replaced with artificial lightweight fine aggregate, both underwater curing and sealing curing are the same as when artificial lightweight fine aggregate is not used. Strength was developed.
また、細骨材の全てを人工軽量細骨材に置き換えた場合であっても、水結合材比を１５％であれば圧縮強度が１３０Ｎ／ｍｍ２以上となり、特に、封緘養生を採用すれば圧縮強度が１４０Ｎ／ｍｍ２以上となる。 Moreover, even when all of the fine aggregates are replaced with artificial lightweight fine aggregates, if the water binder ratio is 15%, the compressive strength becomes 130 N / mm 2 or more, and in particular, if sealing curing is adopted. The compressive strength is 140 N / mm 2 or more.
さらに、水結合材比を２０％として、細骨材の全てを人工軽量細骨材に置き換えた場合であっても、水中養生であれば圧縮強度が１２０Ｎ／ｍｍ２程度、封緘養生であれば１３０Ｎ／ｍｍ２を超える強度となった。 Furthermore, even if the water binder ratio is 20% and all of the fine aggregates are replaced with artificial lightweight fine aggregates, the compressive strength is about 120 N / mm 2 for the underwater curing, and the sealing curing The strength exceeded 130 N / mm 2 .
次に、本実施形態のコンクリート組成物について、自己収縮量の確認を行った結果を示す。
図２の（ａ）および（ｂ）に示すように、人工軽量細骨材を用いていない水結合材比２０％および１５％のコンクリートの自己収縮は、材齢２００日において各々−８３０×１０−６、−８９０×１０−６と大きな収縮ひずみを示した。
Next, the result of having confirmed the self-shrinkage amount about the concrete composition of this embodiment is shown.
As shown in FIGS. 2 (a) and (b), the self-shrinkage of the concrete with 20% and 15% water binder ratio without using artificial lightweight fine aggregates is −830 × 10 at the age of 200 days. A large shrinkage strain of −6 and −890 × 10 −6 was exhibited.
また、細骨材の１００％を人工軽量細骨材に置換した水結合材比２０％および１５％のコンクリートでは、材齢２００日において各々＋５１０×１０−６、＋３００×１０−６の膨張ひずみを示した。 Further, in concrete with 20% and 15% water binder ratio in which 100% of the fine aggregate is replaced with artificial lightweight fine aggregate, the expansion strain is + 510 × 10 −6 and + 300 × 10 −6 respectively at the age of 200 days. showed that.
一方、細骨材の５０％を人工軽量細骨材で置換した水結合材比２０％のコンクリート（すなわち、２７８Ｌ／ｍ３の細骨材のうちの半分（＝１３９Ｌ／ｍ３）を人工軽量細骨材に置換したコンクリート）では、材齢２００日において＋５０×１０−６のやや膨張側のひずみを示した。なお、この結果を考慮すれば、細骨材の絶対容積が２７０〜２９０Ｌ／ｍ３である場合において、そのうちの１３０〜１５０Ｌ／ｍ３を人工軽量細骨材に置換したときは、材齢２００日におけるひずみが膨張側となるか、あるいは、収縮側となった場合でもゼロに近い値になると解される。また、細骨材の５０％を人工軽量細骨材で置換した水結合材比の１５％については、材齢２００日において−２００×１０−６程度の収縮ひずみに抑制された。 On the other hand, 50% of the fine aggregate is replaced with artificial light-weight fine aggregate, which is 20% concrete (that is, half of the 278 L / m 3 fine aggregate (= 139 L / m 3 ) is artificially lightweight. (Concrete replaced with fine aggregate) showed a slightly expanded strain of + 50 × 10 −6 at the age of 200 days. In consideration of this result, when the absolute volume of the fine aggregate is 270 to 290 L / m 3 , when replacing the 130 to 150 L / m 3 with the artificial lightweight fine aggregate, the age of 200 It is understood that even when the strain at the day becomes the expansion side or the contraction side, the value becomes close to zero. Further, about 15% of the water binder ratio in which 50% of the fine aggregates were replaced with artificial lightweight fine aggregates, the shrinkage strain of about −200 × 10 −6 was suppressed at the age of 200 days.
したがって、本実施形態のコンクリート組成物によれば、人工軽量細骨材を採用することによりコンクリートの自己収縮を低減させるとともに、高強度コンクリートとして十分な強度を発現することが可能である。 Therefore, according to the concrete composition of the present embodiment, it is possible to reduce the self-shrinkage of the concrete by adopting the artificial lightweight fine aggregate and to exhibit sufficient strength as high-strength concrete.
以上、本発明の実施形態について説明した。しかし、本発明は、前述の実施形態に限られず、前記の各構成要素については、本発明の趣旨を逸脱しない範囲で、適宜変更が可能である。
例えば、前記実施形態では、細骨材を使用するものとしたが、人工軽量細骨材の量を増加することで細骨材を省略してもよい。
The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and the above-described components can be appropriately changed without departing from the spirit of the present invention.
For example, in the above embodiment, the fine aggregate is used, but the fine aggregate may be omitted by increasing the amount of the artificial lightweight fine aggregate.
また、コンクリート組成物の養生方法は封緘養生に限定されるものではなく、例えば水中養生であってもよい。 Moreover, the curing method of the concrete composition is not limited to sealing curing, and may be, for example, underwater curing.
Claims (3)
前記結合材に対する重量比が１０〜２０％となるように添加された１４５〜１５５ｋｇ／ｍ３の水と、
絶対容積が２７０〜３３０Ｌ／ｍ３の粗骨材と、
絶対容積が８８〜１６８Ｌ／ｍ３の人工軽量細骨材と、を含有することを特徴とする、コンクリート組成物。 A binder comprising at least cement and silica fume;
145 to 155 kg / m 3 of water added so that the weight ratio to the binder is 10 to 20%;
Coarse aggregate having an absolute volume of 270 to 330 L / m 3 ;
A concrete composition comprising: an artificial lightweight fine aggregate having an absolute volume of 88 to 168 L / m 3 .
細骨材の絶対容積が２７０〜２９０Ｌ／ｍ３であり、前記細骨材のうちの１３０〜１５０Ｌ／ｍ３が前記人工軽量細骨材に置換されている、ことを特徴とする、請求項１に記載のコンクリート組成物。 The coarse aggregate has an absolute volume of 290 to 310 L / m 3 ;
The absolute volume of fine aggregate is 270~290L / m 3, the 130~150L / m 3 of fine aggregate is replaced with the artificial lightweight fine aggregates, it is characterized in claim The concrete composition according to 1.
前記セメントが普通ポルトランドセメントであり、
前記普通ポルトランドセメント、前記スラグせっこう系混和材および前記シリカフュームの合計重量を１００としたとき、前記普通ポルトランドセメントの重量が６８〜７２であり、前記スラグせっこう系混和材の重量が１８〜２２であり、前記シリカフュームの重量が８〜１２であることを特徴とする請求項１又は請求項２に記載のコンクリート組成物。 The binder includes a slag / gypsum admixture;
The cement is ordinary Portland cement,
When the total weight of the ordinary Portland cement, the slag gypsum admixture and the silica fume is 100, the weight of the ordinary Portland cement is 68 to 72, and the weight of the slag gypsum admixture is 18 to 22. The concrete composition according to claim 1 or 2, wherein the silica fume has a weight of 8-12.
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