JP2022015947A - Fiber reinforced cement composition - Google Patents
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- JP2022015947A JP2022015947A JP2020119147A JP2020119147A JP2022015947A JP 2022015947 A JP2022015947 A JP 2022015947A JP 2020119147 A JP2020119147 A JP 2020119147A JP 2020119147 A JP2020119147 A JP 2020119147A JP 2022015947 A JP2022015947 A JP 2022015947A
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- 239000000835 fiber Substances 0.000 title claims abstract description 44
- 239000000203 mixture Substances 0.000 title claims abstract description 19
- 239000004568 cement Substances 0.000 title claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 44
- 239000002893 slag Substances 0.000 claims abstract description 26
- 239000011230 binding agent Substances 0.000 claims abstract description 10
- 238000010521 absorption reaction Methods 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims description 23
- 239000004570 mortar (masonry) Substances 0.000 claims description 20
- 229910000863 Ferronickel Inorganic materials 0.000 claims description 16
- 239000010881 fly ash Substances 0.000 claims description 13
- 239000012615 aggregate Substances 0.000 claims 7
- 239000011210 fiber-reinforced concrete Substances 0.000 abstract 2
- 230000000052 comparative effect Effects 0.000 description 49
- 239000004567 concrete Substances 0.000 description 26
- 230000000694 effects Effects 0.000 description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 10
- 230000007423 decrease Effects 0.000 description 10
- 239000004576 sand Substances 0.000 description 10
- 239000003638 chemical reducing agent Substances 0.000 description 6
- 229910021487 silica fume Inorganic materials 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 239000002184 metal Substances 0.000 description 4
- 230000001603 reducing effect Effects 0.000 description 4
- 239000011435 rock Substances 0.000 description 4
- 239000011372 high-strength concrete Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 235000019738 Limestone Nutrition 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 239000006028 limestone Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
Description
本発明は繊維補強セメント組成物に関する。 The present invention relates to a fiber reinforced cement composition.
モルタルやコンクリート(以下、セメント組成物という)の曲げ強度や引張強度を向上させるために、金属繊維などの繊維補強物をセメントに添加することが知られている。特許文献1には鋼繊維を含むコンクリートが開示されている。このコンクリートはセメントと、粗骨材と、細骨材と、鋼繊維と、フライアッシュと、高性能AE減水剤と、を含み、フライアッシュと高性能AE減水剤の配合量が所定の範囲に調整されている。特許文献2には金属繊維を含むセメント組成物が開示されている。このセメント組成物はセメントと、シリカフュームと、フライアッシュと、石膏と、金属繊維と、を含み、シリカフュームとフライアッシュの配合量が所定の範囲に調整されている。 It is known to add fiber reinforcements such as metal fibers to cement in order to improve the bending strength and tensile strength of mortar and concrete (hereinafter referred to as cement composition). Patent Document 1 discloses concrete containing steel fibers. This concrete contains cement, coarse aggregate, fine aggregate, steel fiber, fly ash, and high-performance AE water reducing agent, and the blending amount of fly ash and high-performance AE water reducing agent is within a predetermined range. It has been adjusted. Patent Document 2 discloses a cement composition containing a metal fiber. This cement composition contains cement, silica fume, fly ash, gypsum, and metal fibers, and the blending amount of silica fume and fly ash is adjusted to a predetermined range.
繊維はセメント組成物の強度の向上に寄与するが、反面フレッシュ時の流動性を低下させる。また、セメント組成物においては、ひび割れ防止などの観点から自己収縮の低減が求められている。本発明は流動性が改善され、自己収縮の抑えられた繊維補強セメント組成物を提供することを目的とする。 The fibers contribute to the improvement of the strength of the cement composition, but on the other hand, the fluidity at the time of freshness is reduced. Further, in the cement composition, reduction of self-shrinkage is required from the viewpoint of preventing cracks and the like. It is an object of the present invention to provide a fiber reinforced cement composition having improved fluidity and suppressed self-shrinkage.
本発明の繊維補強セメント組成物は細骨材と結合材と繊維と水とを含み、細骨材は吸水率が1.5%以上のスラグ細骨材であり、繊維の混入率が0.5~2.0%である。 The fiber-reinforced cement composition of the present invention contains a fine aggregate, a binder, fibers and water, and the fine aggregate is a slag fine aggregate having a water absorption rate of 1.5% or more, and the mixing rate of fibers is 0. It is 5 to 2.0%.
本発明によれば、流動性が改善され、自己収縮の抑えられた繊維補強セメント組成物を提供することができる。 According to the present invention, it is possible to provide a fiber reinforced cement composition having improved fluidity and suppressed self-shrinkage.
以下、本発明を、超高強度コンクリートを例に、実施例に基づいて説明する。まず、実施例1~3及び比較例1~3について説明する。表1に実施例1~3と比較例1~3のコンクリートの配合を、表2に使用材料の諸元を示す。なお、表2中、Ig.lossは強熱減量(試料を強熱した際に生じる質量の減少率)を意味し、BETはJIS R 1626「ファインセラミックス粉体の気体吸着BET法による比表面積の測定方法」による測定結果であることを意味する。実施例1~3のコンクリートは、水と、結合材と、細骨材と、粗骨材と、短繊維と、化学混和剤と、を含んでいる。結合材として、セメントとフライアッシュとシリカフュームを用いた。細骨材として大平洋金属株式会社製のフェロニッケルスラグ細骨材(商品名:パムコサンド)を用いた。実施例1~3は、水の単位水量をそれぞれ175kg/m3、155kg/m3、135kg/m3とした。比較例1~3では、細骨材として一般的な硬質砂岩砕砂を用いた。比較例1,2は結合材としてセメントとシリカフュームを用いており、水の単位水量をそれぞれ175kg/m3、155kg/m3とした。比較例1,2では,質量比でセメント:シリカフューム=9:1としている。比較例3は比較例2にフライアッシュを添加したもので、水の単位水量は155kg/m3である。比較例3では、シリカフュームの構成比率(容積比)を比較例2と同程度とし、比較例2のセメントの一部をフライアッシュに置換している。水粉体容積比、短繊維混入率、単位粗骨材量は実施例1~3、比較例1~3で同一とした。短繊維混入率はコンクリート1m3(水、粉体(結合材)、細骨材、粗骨材、空気、短繊維をすべて含む)当たりの短繊維の体積百分率であり、実施例1~3及び比較例1~3では1.0%とした。モルタル細骨材容積比s/morは、細骨材容積/(水、結合材、細骨材の総容積)である。細骨材率s/aは、細骨材の容積/(細骨材と粗骨材の総容積)である。 Hereinafter, the present invention will be described based on examples, using ultra-high-strength concrete as an example. First, Examples 1 to 3 and Comparative Examples 1 to 3 will be described. Table 1 shows the concrete formulations of Examples 1 to 3 and Comparative Examples 1 to 3, and Table 2 shows the specifications of the materials used. In Table 2, Ig.loss means loss on ignition (the rate of decrease in mass generated when the sample is ignited), and BET is JIS R 1626 "specific surface area of fine ceramic powder by gas adsorption BET method". It means that it is a measurement result by "measurement method". The concrete of Examples 1 to 3 contains water, a binder, a fine aggregate, a coarse aggregate, a staple fiber, and a chemical admixture. Cement, fly ash and silica fume were used as binders. Ferronickel slag fine aggregate (trade name: Pamco Sand) manufactured by Pacific Metals Co., Ltd. was used as the fine aggregate. In Examples 1 to 3, the unit water amounts of water were 175 kg / m 3 , 155 kg / m 3 , and 135 kg / m 3 , respectively. In Comparative Examples 1 to 3, general hard sandstone crushed sand was used as the fine aggregate. In Comparative Examples 1 and 2, cement and silica fume were used as binders, and the unit water amount of water was 175 kg / m 3 and 155 kg / m 3 , respectively. In Comparative Examples 1 and 2, the mass ratio is cement: silica fume = 9: 1. Comparative Example 3 is obtained by adding fly ash to Comparative Example 2, and the unit water amount of water is 155 kg / m 3 . In Comparative Example 3, the composition ratio (volume ratio) of silica fume is about the same as that of Comparative Example 2, and a part of the cement of Comparative Example 2 is replaced with fly ash. The water powder volume ratio, the staple fiber mixing ratio, and the unit coarse aggregate amount were the same in Examples 1 to 3 and Comparative Examples 1 to 3. The staple fiber mixing ratio is the volume percentage of the staple fibers per 1 m 3 of concrete (including all of water, powder (bonding material), fine aggregate, coarse aggregate, air, and staple fibers), and is the percentage of the volume of the staple fibers in Examples 1 to 3 and. In Comparative Examples 1 to 3, it was set to 1.0%. The mortar fine aggregate volume ratio s / mor is the fine aggregate volume / (total volume of water, binder, and fine aggregate). The fine aggregate ratio s / a is the volume of the fine aggregate / (total volume of the fine aggregate and the coarse aggregate).
実施例1~3及び比較例1~3では、短繊維として鋼繊維を用いた。鋼繊維の寸法は直径0.2mm、長さ15mmであるが、直径は0.1~1mmの範囲で、長さは10~30mmの範囲で適宜選択することができる。材料としては、コストや強度の観点から鋼製が好ましいが、他の金属、有機繊維などを用いることもできる。 In Examples 1 to 3 and Comparative Examples 1 to 3, steel fibers were used as the short fibers. The dimensions of the steel fiber are 0.2 mm in diameter and 15 mm in length, but the diameter can be appropriately selected in the range of 0.1 to 1 mm and the length in the range of 10 to 30 mm. As the material, steel is preferable from the viewpoint of cost and strength, but other metals, organic fibers and the like can also be used.
図1(a)に実施例1~3と比較例1~3のスランプフローを示す。スランプフローはJIS A 1150:2007「コンクリートのスランプフロー試験方法」に従い測定した。比較例1ではスランプフローは570mm程度であり、実用上最低限の流動性が確保された。これに対し、比較例2ではスランプフローは430mm程度であり、流動性が不足する結果となった。比較例3ではフライアッシュを添加した効果により、流動性が改善された。実施例1~3はいずれも良好な流動性を示し、実施例3(単位水量135kg/m3)でも比較例3と同程度のスランプフローを示した。実施例1~3では比較例1,2と比べて、単位水量の変化に対するスランプフローの変化が緩やかである。これは、単位水量の選択の自由度が大きいことを意味しており、流動性以外のファクタで最適な単位水量を決定する余地が増えることにつながる。比較例1,2ではセメントの練上げが困難となる可能性を踏まえ、実施例1~3よりも高性能減水剤の使用量を増やしており、比較例3でも実施例1~3より高性能減水剤の使用量を若干増やしている。換言すれば、仮に高性能減水剤の使用量を実施例1~3と比較例1~3で同じとすれば、比較例1~3の流動性はさらに低下することになる。さらに別の言い方をすれば、実施例1~3では少ない量の高性能減水剤で、良好な流動性を確保することができることになる。
FIG. 1A shows the slump flows of Examples 1 to 3 and Comparative Examples 1 to 3. The slump flow was measured according to JIS A 1150: 2007 “Concrete slump flow test method”. In Comparative Example 1, the slump flow was about 570 mm, and the minimum fluidity for practical use was secured. On the other hand, in Comparative Example 2, the slump flow was about 430 mm, resulting in insufficient fluidity. In Comparative Example 3, the fluidity was improved by the effect of adding fly ash. All of Examples 1 to 3 showed good fluidity, and Example 3 (
図1(b)はモルタル細骨材容積比を横軸としてスランプフローを示したものである。モルタル細骨材容積比はモルタルの容積に対する細骨材の容積であるから、モルタル細骨材体積比が増加するほど、細骨材がモルタルの流動性を阻害する程度が高くなる。図1(b)より、実施例1、2では比較例1,2,3のいずれと比べても、同じモルタル細骨材容積比におけるスランプフロー値が大きく、モルタル細骨材容積比が22~40%の範囲で良好な流動性が確保されることがわかる。 FIG. 1B shows the slump flow with the mortar fine aggregate volume ratio as the horizontal axis. Since the mortar fine aggregate volume ratio is the volume of the fine aggregate to the volume of the mortar, as the volume ratio of the mortar fine aggregate increases, the degree to which the fine aggregate inhibits the fluidity of the mortar increases. From FIG. 1 (b), in Examples 1 and 2, the slump flow value at the same mortar fine aggregate volume ratio is larger than that of Comparative Examples 1, 2 and 3, and the mortar fine aggregate volume ratio is 22 to 22. It can be seen that good fluidity is ensured in the range of 40%.
図2は、実施例1~3と比較例1~3についてコンクリートの自己収縮ひずみを示す。測定は、日本コンクリート工学協会「超流動コンクリート研究委員会報告書(II)」に示される「高流動コンクリートの自己収縮試験方法」を参考に、20℃封緘状態とした100×100×400mmの角柱供試体の打込み直後からの長さ変化を供試体の中心に設置した埋込み型ひずみ計で測定することにより行った。比較例1~3はコンクリート打設直後の自己収縮が大きく、大きなひずみが生じた。特に、一般的な結合材と細骨材を使用した比較例1,2では、コンクリート打設後28日目に800(×10-6)程度の自己収縮ひずみが発生した。これに対し実施例1~3では、自己収縮が抑えられ、コンクリート打設後28日目のひずみは200~400(×10-6)程度に抑えられた。実施例1~3の比較より、単位水量が少ないほど(モルタル細骨材容積比が大きいほど)自己収縮は小さくなる傾向にある。図3は、実施例1~3と比較例1~3の圧縮強度の時間的変化を示す。コンクリートは打込み直後から20℃封緘状態とした。圧縮強度については実施例1~3と比較例1~3で大きな差は生じなかった。具体的には、実施例1~3は、強度発現は緩慢であるが、材齢14日程度以降は比較例1~3と同等以上の圧縮強度が得られた。実施例1~3の比較より、単位水量が少ないほど(モルタル細骨材容積比が大きいほど)圧縮強度は高くなる傾向にある。 FIG. 2 shows the self-shrinkage strain of concrete for Examples 1 to 3 and Comparative Examples 1 to 3. For the measurement, refer to the "self-shrinkage test method for high-fluidity concrete" shown in the "Superfluid Concrete Research Committee Report (II)" of the Japan Concrete Engineering Association, and set a square pillar of 100 x 100 x 400 mm in a sealed state at 20 ° C. The change in length immediately after the test piece was driven was measured by an embedded strain gauge installed in the center of the test piece. In Comparative Examples 1 to 3, the self-shrinkage immediately after the concrete was placed was large, and a large strain was generated. In particular, in Comparative Examples 1 and 2 using a general binder and a fine aggregate, a self-shrinkage strain of about 800 (× 10 -6 ) occurred on the 28th day after the concrete was placed. On the other hand, in Examples 1 to 3, self-shrinkage was suppressed, and the strain on the 28th day after concrete placement was suppressed to about 200 to 400 (× 10 -6 ). From the comparison of Examples 1 to 3, the self-shrinkage tends to be smaller as the unit water amount is smaller (the larger the volume ratio of the mortar fine aggregate). FIG. 3 shows the temporal changes in the compressive strength of Examples 1 to 3 and Comparative Examples 1 to 3. Immediately after the concrete was poured, it was sealed at 20 ° C. There was no significant difference in compressive strength between Examples 1 to 3 and Comparative Examples 1 to 3. Specifically, in Examples 1 to 3, the strength development was slow, but after about 14 days of age, compressive strength equal to or higher than that of Comparative Examples 1 to 3 was obtained. From the comparison of Examples 1 to 3, the smaller the unit water amount (the larger the volume ratio of the mortar fine aggregate), the higher the compressive strength tends to be.
実施例1~3の細骨材は風砕処理されたフェロニッケルスラグ細骨材である。風砕処理とは、フェロニッケルを製錬する際に副産される溶融状態のスラグに高圧の空気を吹き付け、細かな球状の粒子に分離し、分離されて空中を飛翔する粒子を壁に衝突させる処理である。高温の粒子は空中を飛翔する際に冷却され、最終的に球状に固められる。このようにして製造されたフェロニッケルスラグ細骨材は吸水率が比較的大きくなる場合がある。そしてこのフェロニッケルスラグ細骨材をコンクリートに用いると、吸水された水が放出されることで、ペーストの収縮を低減する「内部養生効果」が発揮される。このような理由により、風砕処理されたフェロニッケルスラグ細骨材は、コンクリートの自己収縮ひずみが抑えられると同時に、流動性を高めることができるものと考えられる。 The fine aggregates of Examples 1 to 3 are wind-crushed ferronickel slag fine aggregates. In the wind crushing process, high-pressure air is blown onto the molten slag produced by the smelting of ferronickel to separate it into fine spherical particles, and the separated particles that fly in the air collide with the wall. It is a process to make it. The hot particles are cooled as they fly through the air and eventually solidify into spheres. The ferronickel slag fine aggregate thus produced may have a relatively high water absorption rate. When this ferronickel slag fine aggregate is used for concrete, the absorbed water is released, and the "internal curing effect" that reduces the shrinkage of the paste is exhibited. For this reason, it is considered that the wind-crushed ferronickel slag fine aggregate can suppress the self-shrinkage strain of concrete and at the same time increase the fluidity.
ここで再び図1を参照し、単位水量が同一(155kg/m3)またはモルタル細骨材容積比が同一(31.6%)の実施例2、比較例2,3を比べると、比較例2,3の差の方が比較例3と実施例2の差より大きい。これは、流動性に関しては、フライアッシュを添加した効果の方がフェロニッケルスラグ細骨材を用いた効果より大きいことを意味している。一方、図2において実施例2、比較例2,3を比べると、比較例2,3の差よりも、比較例3と実施例2の差が大きくなっている。これは、自己収縮の低減に関しては、フェロニッケルスラグ細骨材を用いた効果の方がフライアッシュを添加した効果より大きいことを意味している。つまり、コンクリートの自己収縮の低減と流動性の向上を両立させるためには、フライアッシュを添加することが好ましいといえるが、フェロニッケルスラグ細骨材を用いることで、コンクリートの自己収縮のさらなる低減と流動性のさらなる向上が可能となることがわかる。 Here, referring to FIG. 1 again, when comparing Examples 2 and Comparative Examples 2 and 3 having the same unit water volume (155 kg / m 3 ) or the same mortar fine aggregate volume ratio (31.6%), Comparative Examples. The difference between a few is larger than the difference between Comparative Example 3 and Example 2. This means that the effect of adding fly ash is greater than the effect of using ferronickel slag fine aggregate in terms of fluidity. On the other hand, when Example 2 and Comparative Examples 2 and 3 are compared in FIG. 2, the difference between Comparative Example 3 and Example 2 is larger than the difference between Comparative Examples 2 and 3. This means that the effect of using ferronickel slag fine aggregate is greater than the effect of adding fly ash in terms of reducing self-shrinkage. In other words, it can be said that it is preferable to add fly ash in order to reduce the self-shrinkage of concrete and improve the fluidity, but by using ferronickel slag fine aggregate, the self-shrinkage of concrete is further reduced. It can be seen that the liquidity can be further improved.
次に、実施例4~7及び比較例4について説明する。表1に実施例4~7及び比較例4のコンクリートの配合を示す。使用材料の諸元は表2に示す通りである。実施例4~7及び比較例4では、短繊維混入率が実施例1~3及び比較例1~3と異なっている。 Next, Examples 4 to 7 and Comparative Example 4 will be described. Table 1 shows the concrete formulations of Examples 4 to 7 and Comparative Example 4. The specifications of the materials used are as shown in Table 2. In Examples 4 to 7 and Comparative Example 4, the staple fiber mixing rate is different from that of Examples 1 to 3 and Comparative Examples 1 to 3.
実施例4,5と比較例4では、短繊維混入率を2.0%としている。実施例4,5はそれぞれ、短繊維混入率以外は実施例1,2に対応している。実施例4と実施例5を比較すると、単位水量の低下(またはモルタル細骨材容積比の増加)とともにスランプフローが低下しており、その傾向は実施例1,2と同様である。さらに、実施例1,4と比較例1,4を比較すると、実施例1に対する実施例4のスランプフローの低下の程度(約150mm)は、比較例1に対する比較例4のスランプフローの低下の程度(約300mm)より小さい。実施例6は単位水量を実施例2と同じとして、短繊維混入率を1.5%としている。スランプフローは実施例2(短繊維混入率1.0%)と実施例5(短繊維混入率2.0%)の中間にある。実施例7は単位水量を実施例3と同じとして、短繊維混入率を0.5%としている。短繊維混入率が低いため、大きなスランプフローが得られている。実施例1~7より、単位水量135~175kg/m3の範囲(及びモルタル細骨材容積比約22~41%の範囲)且つ短繊維混入率0.5~2.0%の範囲では、短繊維混入率の変動に対し、スランプフローが実施例1~3と同様の傾向で変動すると考えられる。 In Examples 4 and 5 and Comparative Example 4, the staple fiber mixing rate is 2.0%. Examples 4 and 5 correspond to Examples 1 and 2, respectively, except for the staple fiber mixing ratio. Comparing Example 4 and Example 5, the slump flow decreases with the decrease in the unit water amount (or the increase in the volume ratio of the mortar fine aggregate), and the tendency is the same as in Examples 1 and 2. Further, when Examples 1 and 4 and Comparative Examples 1 and 4 are compared, the degree of decrease in the slump flow of Example 4 with respect to Example 1 (about 150 mm) is the decrease in slump flow of Comparative Example 4 with respect to Comparative Example 1. It is smaller than the degree (about 300 mm). In Example 6, the unit water amount is the same as that in Example 2, and the staple fiber mixing rate is 1.5%. The slump flow is between Example 2 (staple mixing rate 1.0%) and Example 5 (staple mixing rate 2.0%). In Example 7, the unit water amount is the same as that in Example 3, and the staple fiber mixing rate is 0.5%. Since the staple fiber mixing rate is low, a large slump flow is obtained. From Examples 1 to 7, in the range of unit water volume of 135 to 175 kg / m 3 (and the range of mortar fine aggregate volume ratio of about 22 to 41%) and the staple fiber mixing ratio of 0.5 to 2.0%. It is considered that the slump flow fluctuates in the same tendency as in Examples 1 to 3 with respect to the fluctuation of the staple fiber mixing ratio.
一方、図2には実施例4,7におけるコンクリートの自己収縮ひずみを示している。上述のように、実施例4は実施例1に対して短繊維混入率だけが異なっているが、自己収縮ひずみはほぼ実施例1と同様の傾向を示している。実施例7は実施例3に対して短繊維混入率だけが異なっているが、自己収縮ひずみはほぼ実施例3と同様の傾向を示している。これより、自己収縮の低下には、主に細骨材の種類が寄与しており、短繊維混入率はほとんど影響を及ぼさないことが分かる。また、実施例4と比較例4の比較から、短繊維混入率が2%の場合も、フライアッシュが流動性の向上に対して一定の効果を有することが分かり、自己収縮の抑制にも一定の効果を有することが推測される。 On the other hand, FIG. 2 shows the self-shrinkage strain of concrete in Examples 4 and 7. As described above, Example 4 differs from Example 1 only in the staple fiber mixing ratio, but the self-shrinkage strain shows almost the same tendency as in Example 1. Example 7 differs from Example 3 only in the staple fiber mixing ratio, but the self-shrinkage strain shows almost the same tendency as in Example 3. From this, it can be seen that the type of fine aggregate mainly contributes to the decrease in self-shrinkage, and the staple fiber mixing rate has almost no effect. Further, from the comparison between Example 4 and Comparative Example 4, it was found that fly ash has a certain effect on the improvement of fluidity even when the staple fiber mixing ratio is 2%, and it is also constant in suppressing self-shrinkage. It is presumed to have the effect of.
繊維はコンクリートの曲げ強度や引張強度を高めるために添加されるため、混入率が高いほどコンクリート強度は向上する。一方、混入率が高いと流動性は低下する。上述の実施例1~7及び比較例1~4からわかるように、0.5~2.0%程度の混入率でコンクリートの自己収縮の低下と流動性の向上を両立させることができる。 Since fibers are added to increase the bending strength and tensile strength of concrete, the higher the mixing ratio, the higher the concrete strength. On the other hand, if the mixing rate is high, the liquidity decreases. As can be seen from Examples 1 to 7 and Comparative Examples 1 to 4 described above, it is possible to achieve both a decrease in self-shrinkage of concrete and an improvement in fluidity at a mixing ratio of about 0.5 to 2.0%.
水の単位水量は上述の実施例1~7の範囲、すなわち135~175kg/m3の範囲から適宜選択することができる(同様に、モルタル細骨材容積比は約22~41%の範囲から適宜選択することができる)。135~175kg/m3の範囲であれば、流動性の確保と自己収縮の低減を両立することができる。流動性を重視する場合、単位水量を大きくすることが好ましく、自己収縮の低減を重視する場合、単位水量を小さくすることが好ましい。 The unit water amount of water can be appropriately selected from the above-mentioned range of Examples 1 to 7, that is, the range of 135 to 175 kg / m 3 (similarly, the mortar fine aggregate volume ratio is from the range of about 22 to 41%). Can be selected as appropriate). If it is in the range of 135 to 175 kg / m 3 , it is possible to secure fluidity and reduce self-shrinkage at the same time. When emphasis is placed on fluidity, it is preferable to increase the unit water amount, and when emphasis is placed on reducing self-shrinkage, it is preferable to decrease the unit water amount.
以上本発明を実施例によって説明したが、本発明は上述の実施例に限定されない。例えば、本発明は超高強度コンクリートだけでなく、高強度コンクリートや一般的なコンクリートにも適用することができる。あるいは、粗骨材は省略することができる。すなわち、本発明はコンクリートだけでなくモルタルにも適用可能である。また、細骨材としては一定以上の吸水率、例えば1.5%以上、好ましくは2.5%以上の吸水率を有するスラグ細骨材であれば、実施例1~7で用いたフェロニッケルスラグ細骨材と同等の効果を奏すると考えられる。 Although the present invention has been described above by way of examples, the present invention is not limited to the above-mentioned examples. For example, the present invention can be applied not only to ultra-high-strength concrete but also to high-strength concrete and general concrete. Alternatively, the coarse aggregate can be omitted. That is, the present invention can be applied not only to concrete but also to mortar. Further, as the fine aggregate, if the slag fine aggregate has a water absorption rate of a certain level or more, for example, a water absorption rate of 1.5% or more, preferably 2.5% or more, the ferronickel used in Examples 1 to 7 is used. It is considered to have the same effect as slag fine aggregate.
他のスラグ細骨材として、高炉スラグ細骨材が挙げられる。一実施例では、細骨材として、実施例1~7で用いたフェロニッケルスラグ細骨材と、高炉スラグ細骨材と、安山岩砕砂と、硬質砂岩砕砂と、石灰岩砕砂を用い、水結合材比、混和剤添加量などの他の配合条件を同一としてモルタルを作製し、自己収縮ひずみを測定した。図4に示すように、高炉スラグ細骨材はフェロニッケル細骨材と同等の自己収縮低減効果が確認された。モルタルの流動性を示すJPロート14を、土木学会基準JSCE-F541-1999「充填モルタルの流動性試験方法」に従って測定した。JPロート14はフェロニッケルスラグ細骨材で66(s)、高炉スラグ細骨材で57(s)、安山岩砕砂委で131(s)、硬質砂岩砕砂で147(s)、石灰岩砕砂で70(s)であり、高炉スラグ細骨材はフェロニッケル細骨材と同等の流動性を有することが確認された。高炉スラグ細骨材の吸水率は1.6%であった。本実施例では繊維を混入していないため、繊維を混入した場合、流動性は低下する可能性があるが、繊維を混入した場合でも自己収縮の低減効果と流動性に関しては、高炉スラグ細骨材はフェロニッケル細骨材と同等の性能を発揮すると考えられる。
Other examples of slag fine aggregate include blast furnace slag fine aggregate. In one embodiment, the ferronickel slag fine aggregate used in Examples 1 to 7, the blast furnace slag fine aggregate, the Anzan rock crushed sand, the hard sand rock crushed sand, and the limestone crushed sand are used as the fine aggregate, and the water binder is used. A mortar was prepared under the same other compounding conditions such as the ratio and the amount of admixture added, and the self-shrinkage strain was measured. As shown in FIG. 4, it was confirmed that the blast furnace slag fine aggregate had the same self-shrinkage reducing effect as the ferronickel fine aggregate. The
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