JP7270423B2 - Method for estimating drying shrinkage strain - Google Patents
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Description
本発明は、セメントペースト硬化体、コンクリート、およびモルタル(以下「セメント質硬化体」という。)の、JIS A 1129-1、JIS A 1129-2、またはJIS A 1129-3(以下「JIS A 1129-1~3」という。)に準拠して測定した、乾燥期間が6か月における乾燥収縮ひずみの値を早期に推定する、乾燥収縮ひずみの推定方法に関する。 The present invention relates to hardened cement paste, concrete, and mortar (hereinafter referred to as "hardened cementitious material") according to JIS A 1129-1, JIS A 1129-2, or JIS A 1129-3 (hereinafter referred to as "JIS A 1129 -1 to 3”), and relates to a method for estimating drying shrinkage strain for early estimation of the value of drying shrinkage strain in a drying period of 6 months.
従来、セメント質硬化体の乾燥収縮ひずみを測定する方法は、JIS A 1129-1に規定するコンパレータを用いる方法、JIS A 1129-2に規定するコンタクトゲージを用いる方法、およびJIS A 1129-3に規定するダイヤルゲージを用いる方法がある。しかし、これらの方法はいずれも、乾燥期間が6か月における乾燥収縮ひずみの値を得るのに、6か月もの長期間を要するほか、所定の期間毎に、10cm×10cm×40cmの供試体(セメント質硬化体)の長さを測定しなければならず、測定作業に手間がかかった。 Conventionally, the method for measuring the drying shrinkage strain of hardened cementitious bodies is a method using a comparator specified in JIS A 1129-1, a method using a contact gauge specified in JIS A 1129-2, and a method using a contact gauge specified in JIS A 1129-3. There is a method using a prescribed dial gauge. However, all of these methods require a long period of 6 months to obtain the value of drying shrinkage strain in a drying period of 6 months. The length of the (hardened cementum) had to be measured, and the measurement work was troublesome.
そこで、特許文献1では、コンクリートの乾燥収縮ひずみを、早期に評価する方法が提案されている。該方法は、温度80℃における乾燥期間28日目の乾燥収縮ひずみの実測値と、温度20℃における最終乾燥収縮ひずみ値との関係式、または、温度80℃における最終乾燥収縮ひずみ値と、温度20℃における最終乾燥収縮ひずみ値との関係を、それぞれ一次式で近似した関係式を用いて、任意の長期材齢におけるコンクリートの乾燥収縮ひずみを早期に評価する方法である。しかし、この方法では、関係式を得るのに手間がかかるほか、温度80℃における最終乾燥収縮ひずみ値と、温度20℃における最終乾燥収縮ひずみ値との関係が線形でない場合は、評価の精度が低下する。
Therefore,
そこで、本発明は、JIS A 1129-1~3に準拠して測定した、乾燥期間6か月における乾燥収縮ひずみの値を早期に推定する、乾燥収縮ひずみの推定方法を提供することを目的とする。 Therefore, an object of the present invention is to provide a drying shrinkage strain estimation method for early estimation of the drying shrinkage strain value in a drying period of 6 months, measured in accordance with JIS A 1129-1 to 3. do.
本発明者は、前記目的にかなう乾燥収縮ひずみの推定方法を鋭意検討した結果、特定の乾燥収縮ひずみ測定装置を用いて測定した乾燥収縮ひずみの終局値に特定の係数を乗ずれば、前記目的を達成できることを見出し、本発明を完成させた。
すなわち、本発明は、以下の構成を有する乾燥収縮ひずみの推定方法である。
As a result of intensive studies on a method for estimating drying shrinkage strain that satisfies the above object, the present inventor found that if the ultimate value of drying shrinkage strain measured using a specific drying shrinkage strain measuring device is multiplied by a specific coefficient, the above object can be obtained. can be achieved, and completed the present invention.
That is, the present invention is a drying shrinkage strain estimation method having the following configuration.
[1]下記(A)および(B)の工程を経て取得した乾燥収縮ひずみの終局値に、表1に記載のセメントの種類に応じて選択した係数を乗じて得た値を、JIS A 1129-1、JIS A 1129-2、またはJIS A 1129-3に準拠して測定した、乾燥期間6か月における乾燥収縮ひずみの値として推定する、乾燥収縮ひずみの推定方法(ただし、推定対象のコンクリートの骨材と下記供試体の骨材は同一である。)。
(A)2個以上のレーザー変位計、乾燥収縮ひずみ測定用の供試体を支持するための正三角形の3つの頂点または正方形の4つの頂点を形成するように配置してなる支持部材、および、該支持部材の一部を埋設してなる台座、を少なくとも含む、乾燥収縮ひずみ測定装置の前記支持部材上に、円板状または四角板状の供試体の中心が、前記支持部材が形成する正三角形または正方形の中心と一致するように載置する、供試体の載置工程
(B)該供試体の周囲の側面に、レーザー変位計からレーザーを照射して、レーザー変位計と供試体の周囲の側面の間の距離を測定し、該距離が一定に達した時点の供試体の乾燥収縮ひずみを、該供試体の乾燥収縮ひずみの終局値として取得する、乾燥収縮ひずみの終局値の取得工程
[表1]
[2]2~4個の前記レーザー変位計を、前記支持部材が形成する正三角形または正方形の中心から等間隔の位置に、レーザー照射面を該中心に向けて配置してなる、前記[1]に記載の乾燥収縮ひずみの推定方法。
[3]2~6個の前記レーザー変位計を、該レーザー変位計から照射されたレーザーが60~300°の角度で交差するように配置してなる、前記[1]または[2]に記載の乾燥収縮ひずみの推定方法。
[4]前記供試体の厚さが5~20mmである、前記[1]~[3]のいずれかに記載の乾燥収縮ひずみの推定方法。
[5]前記支持部材上に前記供試体を載置したままの状態で、前記供試体を乾燥する、前記[1]~[4]のいずれかに記載の乾燥収縮ひずみの推定方法。
[1] The value obtained by multiplying the final value of the drying shrinkage strain obtained through the steps (A) and (B) below by a coefficient selected according to the type of cement described in Table 1, and JIS A 1129 -1, JIS A 1129-2, or JIS A 1129-3, estimated as the value of drying shrinkage strain in a drying period of 6 months, method for estimating drying shrinkage strain (However, the concrete to be estimated The aggregate of the following specimens is the same as that of the following specimens.) .
(A) two or more laser displacement gauges, a support member arranged to form three vertices of an equilateral triangle or four vertexes of a square for supporting a specimen for drying shrinkage strain measurement, and The center of a disk-shaped or square plate-shaped test piece is placed on the support member of the drying shrinkage strain measuring device, which includes at least a pedestal formed by embedding a part of the support member. (B) A step of placing the test piece so as to match the center of the triangle or square. A step of acquiring the final value of drying shrinkage strain, in which the distance between the sides of the specimen is measured, and the drying shrinkage strain of the specimen when the distance reaches a constant value is obtained as the ultimate value of the drying shrinkage strain of the specimen. [Table 1]
[2] 2 to 4 laser displacement gauges are arranged at equal intervals from the center of the equilateral triangle or square formed by the support member, with the laser irradiation surface facing the center, wherein the [1] ] Method for estimating drying shrinkage strain described in .
[3] The above [1] or [2], wherein 2 to 6 laser displacement gauges are arranged so that the laser beams emitted from the laser displacement gauges intersect at an angle of 60 to 300°. method for estimating the drying shrinkage strain of
[4] The method for estimating drying shrinkage strain according to any one of [1] to [3], wherein the specimen has a thickness of 5 to 20 mm.
[5] The drying shrinkage strain estimation method according to any one of [1] to [4], wherein the test piece is dried while the test piece is placed on the support member.
本発明の乾燥収縮ひずみの推定方法は、JIS A 1129-1~3に準拠して測定した、セメント質硬化体の乾燥期間6か月における乾燥収縮のひずみを、早期に精度よく推定できる。また、本発明で用いる供試体は、JIS A 1129-1~3で用いる供試体に比べ小さく、供試体を動かすなどの作業が容易なため、乾燥収縮ひずみの測定作業の労力を大幅に軽減できる。 The method for estimating the drying shrinkage strain of the present invention enables early and accurate estimation of the drying shrinkage strain of a hardened cementitious material during a drying period of 6 months, measured according to JIS A 1129-1 to 3. In addition, the specimen used in the present invention is smaller than the specimen used in JIS A 1129-1 to 3, and the work such as moving the specimen is easy, so the labor for measuring the drying shrinkage strain can be greatly reduced. .
本発明は、前記(A)および(B)の工程を経て取得した乾燥収縮ひずみの終局値に、表1に記載のセメントの種類に応じて選択した係数を乗じて得た値を、JIS A 1129-1~3に準拠して測定した、乾燥期間6か月における乾燥収縮ひずみの値として推定する、乾燥収縮ひずみの推定方法である。
以下、本発明について、乾燥収縮ひずみ測定装置、乾燥収縮ひずみの測定と乾燥収縮ひずみの終局値の取得、および、乾燥収縮ひずみの推定方法に分けて詳細に説明する。
In the present invention, the value obtained by multiplying the final value of the drying shrinkage strain obtained through the steps (A) and (B) by a coefficient selected according to the type of cement described in Table 1 is JIS A 1129-1 to 3, and estimated as the value of the drying shrinkage strain in a drying period of 6 months.
Hereinafter, the present invention will be described in detail separately for a drying shrinkage strain measuring device, measurement of drying shrinkage strain, acquisition of an ultimate value of drying shrinkage strain, and a method for estimating drying shrinkage strain.
1.乾燥収縮ひずみ測定装置
該装置は、図1~4に例示するように、(A)2個以上のレーザー変位計、(B)乾燥収縮ひずみ測定用の供試体を支持するための正三角形の3つの頂点または正方形の4つの頂点を形成するように配置してなる支持部材、および、(C)該支持部材の一部を埋設してなる台座を、少なくとも含む装置である。
1. Drying shrinkage strain measuring device As illustrated in FIGS. 1 to 4, the device includes (A) two or more laser displacement meters, (B) three equilateral triangles for supporting the specimen for drying shrinkage strain measurement. The device includes at least a supporting member arranged to form four vertices or four vertices of a square, and (C) a pedestal having a portion of the supporting member embedded.
(A)レーザー変位計
本発明で用いるレーザー変位計は、特に制限されず、反射型や透過型等の市販のレーザー変位計が挙げられる。ちなみに、図4に示す4個のレーザー変位計4は、反射型である。
本発明では、乾燥収縮ひずみの測定精度が向上するため、レーザー変位計を2個以上設置する。レーザー変位計が1個では、乾燥収縮ひずみの測定精度が低下するおそれがある。また、レーザー変位計を増やせばデータ数が増え、その分、さらに測定精度が向上するが、装置はコスト高になる。したがって、本発明において、レーザー変位計は、好ましくは2~6個、より好ましくは2~4個設置する。
レーザー変位計は、乾燥収縮ひずみの測定精度が向上し、また、供試体の載置が容易なため、好ましくは、支持部材が形成する正三角形または正方形の中心から等間隔の位置に、レーザー照射面を該中心に向けて設置する。また、乾燥収縮ひずみの測定精度がさらに向上するため、より好ましくは、2~6個の前記レーザー変位計を、該レーザー変位計から照射されたレーザーが60~300°の角度で交差するように配置する。
レーザー変位計を設置する態様は、レーザー変位計を2個設置する場合、例えば、図1に示すように、レーザー変位計を対向して設置するか、図2に示すように、レーザーが90°の角度で交差するように設置し、また、レーザー変位計を4個設置する場合、図3に示すように、2組のレーザー変位計を対向して設置する。
(A) Laser Displacement Gauge The laser displacement gauge used in the present invention is not particularly limited, and commercially available laser displacement gauges such as reflection type and transmission type can be used. Incidentally, the four
In the present invention, two or more laser displacement gauges are installed in order to improve the measurement accuracy of drying shrinkage strain. If there is only one laser displacement meter, there is a risk that the measurement accuracy of the drying shrinkage strain will decrease. Also, if the number of laser displacement meters is increased, the amount of data will increase, and the measurement accuracy will be improved accordingly, but the cost of the device will increase. Therefore, in the present invention, preferably 2 to 6, more preferably 2 to 4 laser displacement gauges are installed.
A laser displacement meter improves the measurement accuracy of drying shrinkage strain and facilitates placement of the test piece. Place the face toward the center. In order to further improve the measurement accuracy of drying shrinkage strain, more preferably, 2 to 6 laser displacement gauges are arranged so that the laser beams emitted from the laser displacement gauges intersect at an angle of 60 to 300°. Deploy.
When two laser displacement meters are installed, for example, as shown in FIG. 1, the laser displacement meters are installed facing each other, or as shown in FIG. If four laser displacement gauges are installed so as to intersect each other at an angle of , two sets of laser displacement gauges are installed facing each other as shown in FIG.
(B)支持部材
支持部材は、供試体を台座から離して、供試体と台座の間に空間を設けるために用いる。この空間を設けることにより、供試体は均質かつ早期に乾燥するため、乾燥収縮ひずみの終局値を早期に測定できる。支持部材の形状は、特に制限されず、図1等に示す球状や柱状等が挙げられる。なお、支持部材が柱状の場合、供試体と点で接触するように、好ましくは、供試体に接する支持部材の面を半球状にする。
また、支持部材の数は、3点以上あれば供試体を安定して載置できるが、支持部材が多すぎると、装置の製造に手間がかかるため、支持部材の数は、好ましくは3~4個である。また、前記支持部材は、供試体を安定して載置するためには、好ましくは正三角形または正方形を形成するように設置する。図1~3は、支持部材5が正方形を形成するように、支持部材を設置した例である。なお、前記支持部材は、熱や衝撃による変形を防ぐため、好ましくはインバー鋼材を用いて製造する。
(B) Support member The support member is used to separate the test piece from the pedestal and provide a space between the test piece and the pedestal. By providing this space, the specimen dries uniformly and quickly, so the ultimate value of the drying shrinkage strain can be measured early. The shape of the support member is not particularly limited, and examples thereof include a spherical shape and a columnar shape as shown in FIG. 1 and the like. If the support member is columnar, the surface of the support member contacting the test piece is preferably hemispherical so as to make point contact with the test piece.
If the number of support members is 3 or more, the specimen can be placed stably. There are four. Also, the support members are preferably installed to form an equilateral triangle or square in order to stably mount the specimen. 1 to 3 are examples in which the support members are arranged so that the
(C)台座
台座は、支持部材の一部(下部)を埋設して固定してなるものである。ちなみに、図1~3に示す台座2は正方形の板状である。また、測定精度を向上させるため、台座は水平に保たれていることが好ましい。なお、前記台座は、熱や衝撃による変形を防ぐため、好ましくはインバー鋼材を用いて製造する。
(C) Pedestal The pedestal is fixed by embedding a part (lower part) of the support member. Incidentally, the
(D)供試体載置補助治具
本発明で用いる乾燥収縮ひずみ測定装置では、支持部材上への供試体の載置を容易にするため、供試体載置補助治具を用いてもよい。該供試体載置補助治具は、図4に示すような、台座の外側に設置された2本のピンが挙げられる。図4の乾燥収縮ひずみ測定装置の支持部材上に、例えば、直径10cmの円板状の供試体を載置する場合、前記2本のピンと接触するように前記供試体を支持部材上に載置すれば、供試体の中心と支持部材が形成する正方形の中心が一致するように供試体を載置できる。
なお、供試体載置補助治具は、台座上に設置しても良いし、図4に示すように台座の外側に設置しても良い。また、供試体載置補助治具は、熱や衝撃による変形を防ぐため、好ましくはインバー鋼材を用いて製造する。
(D) Specimen Placement Auxiliary Jig In the drying shrinkage strain measuring apparatus used in the present invention, a specimen placement assistance jig may be used in order to facilitate the placement of the specimen on the supporting member. The test piece placement auxiliary jig includes two pins installed on the outside of the pedestal as shown in FIG. When placing, for example, a disk-shaped specimen with a diameter of 10 cm on the supporting member of the drying shrinkage strain measuring device of FIG. 4, the specimen is placed on the supporting member so as to contact the two pins. Then, the test piece can be placed so that the center of the test piece coincides with the center of the square formed by the supporting members.
Note that the test piece placement auxiliary jig may be installed on the pedestal, or may be installed outside the pedestal as shown in FIG. In order to prevent deformation due to heat or impact, the test piece placement auxiliary jig is preferably made of invar steel.
本発明で用いる乾燥収縮ひずみ測定装置は、図1~4に示すように、2個以上のレーザー変位計、台座、および、供試体の載置を容易にするために必要に応じて供試体載置補助治具を、一体化して構成することが好ましい。この場合、レーザー変位計と台座を設置するための基盤は、熱や衝撃による変形を防ぐため、好ましくはインバー鋼材を用いて製造する。 As shown in FIGS. 1 to 4, the drying shrinkage strain measuring device used in the present invention includes two or more laser displacement gauges, a pedestal, and, if necessary, a specimen mount for facilitating the mounting of the specimen. It is preferable to integrate the placement assisting jig. In this case, the base for installing the laser displacement gauge and the pedestal is preferably manufactured using invar steel in order to prevent deformation due to heat and impact.
2.乾燥収縮ひずみの測定と乾燥収縮ひずみの終局値の取得
本発明において乾燥収縮ひずみの測定は、まず、前記乾燥収縮ひずみ測定装置の台座上に、円板状または四角板状の供試体を載置する(供試体の載置工程)。
本発明では、(1)別の場所で乾燥している供試体を、所定の乾燥期間毎に台座上に載置して、乾燥収縮ひずみを測る方法と、(2)台座上に供試体を載置したままの状態で、供試体を乾燥して、所定の乾燥期間毎に、乾燥収縮ひずみを測る方法、のいずれも可能であるが、多数の供試体の乾燥収縮ひずみを並行して測定できるため、前記(1)の方法が好ましい。
本発明において、供試体が円板状の場合、供試体の直径は、10~30cmであれば、供試体の製造は容易で、また供試体の乾燥が速くなり好ましい。なお、供試体の直径は、より好ましくは10~20cmである。また、供試体の厚さは、5~20mmであれば供試体は割れ難く、また供試体の乾燥がさらに速くなるため好ましい。なお、供試体の厚さは、より好ましくは6~18mm、さらに好ましくは7~15mm、特に好ましくは8~12mmである。
また、供試体が四角板状の場合、四角板の1辺の長さは、好ましくは10~30cm、より好ましくは10~20cmであり、さらに好ましくは、1辺の長さが10~30cmの正方形、特に好ましくは、1辺の長さが10~20cmの正方形である。1辺の長さが10~30cmであれば、供試体の製造は容易で、また供試体の乾燥が速くなる。また、四角板状の供試体の厚さは、好ましくは5~20mm、より好ましくは6~18mm、さらに好ましくは7~15mm、特に好ましくは8~12mmである。供試体の厚さが5~20mmであれば、供試体は割れ難く、また供試体の乾燥はさらに速くなる。
2. Measurement of Drying Shrinkage Strain and Acquisition of Ultimate Value of Drying Shrinkage Strain In the present invention, measurement of drying shrinkage strain is carried out by first placing a disk-shaped or square plate-shaped specimen on the base of the drying shrinkage strain measuring device. (specimen placement step).
In the present invention, (1) a method for measuring drying shrinkage strain by placing a specimen dried in another place on a pedestal for each predetermined drying period, and (2) placing the specimen on the pedestal. It is possible to measure the drying shrinkage strain at each predetermined drying period by drying the test piece while it is placed, but measuring the drying shrinkage strain of a large number of test pieces in parallel. Therefore, the method (1) is preferable.
In the present invention, when the test piece is disk-shaped, it is preferable that the diameter of the test piece is 10 to 30 cm because the test piece can be easily manufactured and the test piece can be dried quickly. The diameter of the specimen is more preferably 10-20 cm. Also, if the thickness of the test piece is 5 to 20 mm, the test piece is less likely to crack and the test piece dries more quickly, which is preferable. The thickness of the specimen is more preferably 6-18 mm, still more preferably 7-15 mm, and particularly preferably 8-12 mm.
In addition, when the specimen is in the shape of a square plate, the length of one side of the square plate is preferably 10 to 30 cm, more preferably 10 to 20 cm, and still more preferably 10 to 30 cm. A square, particularly preferably a square with a side length of 10 to 20 cm. If the length of one side is 10 to 30 cm, the production of the specimen is easy and the drying of the specimen is quick. The thickness of the square plate-shaped specimen is preferably 5 to 20 mm, more preferably 6 to 18 mm, still more preferably 7 to 15 mm, and particularly preferably 8 to 12 mm. If the thickness of the test piece is 5-20 mm, the test piece is less likely to crack, and the drying of the test piece is faster.
本発明における乾燥収縮ひずみの測定では、レーザー変位計を用いて供試体の周囲の側面にレーザーを照射して、レーザー変位計と供試体の周囲の側面の間の距離を測定することにより、供試体の乾燥収縮ひずみを測る。そして、レーザー変位計と供試体の周囲の側面の間の距離が一定に達した時点の供試体の乾燥収縮ひずみを、該供試体の乾燥収縮ひずみの終局値として取得する(乾燥収縮ひずみの終局値の取得工程)。ここで、レーザー変位計と供試体の周囲の側面の間の距離が一定に達した時点とは、7日間での当該距離の変化量が0.001mm以下になった時点を意味する。
なお、本発明における乾燥収縮ひずみの測定では、乾燥収縮ひずみの測定間隔は任意であるが、乾燥収縮ひずみの終局値を早期に得るためや、測定の手間を軽減するため、好ましくは乾燥期間1~10日毎、より好ましくは乾燥期間1~7日毎である。
In the measurement of drying shrinkage strain in the present invention, a laser displacement meter is used to irradiate the side surface of the specimen with a laser, and the distance between the laser displacement meter and the side surface of the specimen is measured. Measure the drying shrinkage strain of the sample. Then, the drying shrinkage strain of the specimen when the distance between the laser displacement meter and the peripheral side surface of the specimen reaches a certain value is obtained as the ultimate value of the drying shrinkage strain of the specimen (ultimate drying shrinkage strain value acquisition step). Here, the point in time when the distance between the laser displacement meter and the peripheral side surface of the specimen reaches a constant point means the point in time when the amount of change in the distance becomes 0.001 mm or less in 7 days.
In the measurement of drying shrinkage strain in the present invention, the measurement interval of drying shrinkage strain is arbitrary, but in order to obtain the final value of drying shrinkage strain early and to reduce the labor of measurement, it is preferable that the drying period is 1 Every ~10 days, more preferably every 1-7 days during the drying period.
3.乾燥収縮ひずみの推定方法
本発明の乾燥収縮ひずみの推定方法は、前記(A)および(B)の工程を経て取得した乾燥収縮ひずみの終局値に、表1に記載のセメントの種類に応じて選択した係数を乗じて得た値を、JIS A 1129-1~3に準拠して測定した、乾燥期間6か月における乾燥収縮ひずみの値として推定する方法である。
本発明の推定方法によれば、図5に示すとおり、JIS A 1129-1~3に準拠して測定した乾燥期間6か月におけるセメント質硬化体の乾燥収縮ひずみの値、特に、圧縮強度が18N/mm2以上のセメント質硬化体の乾燥収縮ひずみの値を、100日以内という短期間で精度よく推定できる。
また、本発明の乾燥収縮ひずみの推定方法が適用できるセメント質硬化体の種類は、特に限定されず、普通コンクリートのほか、収縮低減剤または膨張材を含むコンクリート(図5参照)、速硬型コンクリート、軽量コンクリート、および高強度コンクリート等のセメント質硬化体にも適用できる。
また、コンクリートが収縮低減剤を含む場合、収縮低減剤の単位量は、好ましくは12kg/m3以下、より好ましくは9kg/m3以下、さらに好ましく6kg/m3以下であり、また、コンクリートが膨張材を含む場合、膨張材の単位量は、好ましくは30kg/m3以下、より好ましくは25kg/m3以下、さらに好ましく20kg/m3以下である。
また、セメントが高炉セメントである場合、該セメントは、好ましくは高炉セメントA種またはB種である。セメントがシリカフュームを含む場合、セメント中のシリカフュームの含有率は、好ましくは20質量%以下である。
3. Method for estimating drying shrinkage strain The method for estimating drying shrinkage strain of the present invention is based on the final value of drying shrinkage strain obtained through the steps (A) and (B) above, depending on the type of cement described in Table 1. This is a method of estimating the value obtained by multiplying the selected coefficient as the value of the drying shrinkage strain in a drying period of 6 months, measured in accordance with JIS A 1129-1 to 3.
According to the estimation method of the present invention, as shown in FIG. The value of drying shrinkage strain of hardened cementitious material of 18 N/mm 2 or more can be accurately estimated within a short period of 100 days.
The type of hardened cementitious material to which the drying shrinkage strain estimation method of the present invention can be applied is not particularly limited. It can also be applied to cementitious hardened bodies such as concrete, lightweight concrete, and high-strength concrete.
In addition, when the concrete contains a shrinkage reducing agent, the unit amount of the shrinkage reducing agent is preferably 12 kg/m 3 or less, more preferably 9 kg/m 3 or less, and still more preferably 6 kg/m 3 or less. When an expanding material is included, the unit amount of the expanding material is preferably 30 kg/m 3 or less, more preferably 25 kg/m 3 or less, and even more preferably 20 kg/m 3 or less.
Moreover, when the cement is blast-furnace cement, the cement is preferably blast-furnace cement A or B. When the cement contains silica fume, the content of silica fume in the cement is preferably 20% by mass or less.
以下、本発明を実施例により説明するが、本発明はこれらの実施例に限定されない。
1.使用材料
(1)セメント(太平洋セメント社製)
(i)普通ポルトランドセメント(略号:NC)
(ii)高炉セメントB種(略号:BB)
(iii)中庸熱ポルトランドセメント(略号:MC)
(iv)低熱ポルトランドセメント(略号:LC)
(v)フライアッシュセメントC種(略号:FA)
ブレーン比表面積は3300cm2/g、フライアッシュの含有率は30質量%である。
(2)細骨材(略号:S)
山砂(表乾密度2.56g/cm3)
(3)粗骨材(略号:G)
砂岩砕石(表乾密度2.61g/cm3)
(4)水(略号:W)
水道水
(5)AE減水剤(略号:LS)
リグニンスルホン酸系AE減水剤、商品名 ポゾリスNo.70[登録商標](BASF社製)
(6)AE剤
商品名 マスターエア404[登録商標](BASF社製)
(7)収縮低減剤(略号:SR)
商品名 テトラガードAS21(太平洋マテリアル社製)
(8)膨張材(略号:EX)
太平洋ハイパーエクスパン(太平洋マテリアル社製)
EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.
1. Materials used (1) Cement (manufactured by Taiheiyo Cement Co., Ltd.)
(i) Ordinary Portland cement (abbreviation: NC)
(ii) Blast furnace cement type B (abbreviation: BB)
(iii) Moderate heat Portland cement (abbreviation: MC)
(iv) Low heat Portland cement (abbreviation: LC)
(v) Fly ash cement Class C (abbreviation: FA)
The Blaine specific surface area is 3300 cm 2 /g, and the fly ash content is 30% by mass.
(2) Fine aggregate (abbreviation: S)
Mountain sand (surface dry density 2.56 g/cm 3 )
(3) Coarse aggregate (abbreviation: G)
Sandstone crushed stone (surface dry density 2.61 g/cm 3 )
(4) Water (abbreviation: W)
Tap water (5) AE water reducing agent (abbreviation: LS)
Lignin sulfonic acid-based AE water reducing agent, trade name Pozzolith No. 70 [registered trademark] (manufactured by BASF)
(6) AE agent Product name Master Air 404 [registered trademark] (manufactured by BASF)
(7) Shrinkage reducing agent (abbreviation: SR)
Product name: Tetraguard AS21 (manufactured by Taiheiyo Materials Co., Ltd.)
(8) Expansive material (abbreviation: EX)
Taiheiyo Hyper Expan (manufactured by Taiheiyo Materials Co., Ltd.)
2.乾燥収縮ひずみ測定用の供試体の作製
表2に示す配合に従い、前記の各材料を容量50リッターのパン型ミキサに一括して投入し、2分間混練した後、混練物を内径10cm、高さ20cmの型枠に打設し成形してコンクリートを得た。次に、該コンクリートを20℃で1日間湿空養生した後に脱型し、さらに20℃で7日間水中養生した。水中養生した後、コンクリートの高さ方向の中央部付近を切断して、直径10cm、厚さ10mmの乾燥収縮ひずみ測定用の供試体を各3個作製した。
なお、JIS A 1108「コンクリートの圧縮強度試験」に準拠して測定したコンクリートA、D、およびFの材齢28日の圧縮強度は、それぞれ47N/mm2、40N/mm2、および46N/mm2であった。
2. Preparation of test piece for drying shrinkage strain measurement According to the formulation shown in Table 2, each of the above materials was put into a pan-type mixer with a capacity of 50 liters at once and kneaded for 2 minutes. Concrete was obtained by pouring into a formwork of 20 cm and molding. Next, the concrete was cured in wet air at 20° C. for 1 day, removed from the mold, and further cured in water at 20° C. for 7 days. After curing in water, the vicinity of the central portion in the height direction of the concrete was cut to prepare three specimens each having a diameter of 10 cm and a thickness of 10 mm for measurement of drying shrinkage strain.
The compressive strengths of concretes A, D, and F measured in accordance with JIS A 1108 "Concrete Compressive Strength Test" at a material age of 28 days are 47 N/mm 2 , 40 N/mm 2 , and 46 N/mm, respectively. was 2 .
3.供試体の乾燥収縮ひずみの測定
乾燥収縮ひずみ測定用の供試体を、図1に示す乾燥収縮ひずみ測定装置の台座に固定した支持部材に、該供試体の中心と支持部材が形成する正方形の中心が一致するように載置したまま、室温20±2℃、相対湿度60±5%の条件で乾燥した。そして、乾燥期間7日毎に、対向する2組のレーザー変位計を用いて、レーザー変位計と供試体の周囲の側面の間の距離を測定して平均値を求め、この平均値と乾燥開始直前におけるレーザー変位計と供試体の周囲の側面の間の距離との差を、乾燥開始直前における供試体の直径で除した値を当該供試体の乾燥収縮ひずみとして算出し、さらに、この3個の供試体の乾燥収縮ひずみ(平均値)を平均して、全体の乾燥収縮ひずみを算出した。その結果を表3と図4に示す。
ただし、表3中の数値の意味は以下のとおりである。
(i)「ひずみの終局値 本発明」欄内の数値は、図1の乾燥収縮ひずみ測定装置を用いて測定した乾燥収縮ひずみの終局値を示す。
(ii)「ひずみの終局値 JIS法」欄内の数値は、JIS A 1129-2「モルタル及びコンクリートの長さ変化測定方法 第2部:コンタクトゲージ方法」(以下「JIS法」という。)に準拠して測定した、乾燥収縮ひずみの終局値を示す。
(iii)「乾燥期間6か月のひずみの実測値」欄内の数値は、前記JIS法に準拠して測定した、乾燥期間6か月における乾燥収縮ひずみの値(実測値)を示す(比較例)。
(iv)「乾燥期間6か月のひずみの推定値」欄内の数値は、実施例として、乾燥収縮ひずみの終局値に、表1から供試体中のセメントの種類に応じて選択した係数を乗じて得た値(推定値)を示す(実施例)。
3. Measurement of drying shrinkage strain of a specimen A specimen for drying shrinkage strain measurement is placed on a supporting member fixed to the pedestal of the drying shrinkage strain measuring device shown in FIG. It was dried under conditions of a room temperature of 20±2° C. and a relative humidity of 60±5%. Then, every 7 days during the drying period, using two pairs of laser displacement gauges facing each other, the distance between the laser displacement gauge and the side surface around the specimen is measured to obtain an average value, and this average value and immediately before the start of drying The difference between the distance between the laser displacement meter and the side surface of the specimen at the time is divided by the diameter of the specimen immediately before the start of drying, and the drying shrinkage strain of the specimen is calculated. The overall drying shrinkage strain was calculated by averaging the drying shrinkage strains (average values) of the specimens. The results are shown in Table 3 and FIG.
However, the meaning of the numerical values in Table 3 is as follows.
(i) Ultimate value of strain The numerical value in the "Invention" column indicates the ultimate value of the drying shrinkage strain measured using the drying shrinkage strain measuring device of FIG.
(ii) The values in the "Ultimate strain value JIS method" column are based on JIS A 1129-2 "Mortar and concrete length change measurement method Part 2: Contact gauge method" (hereinafter referred to as "JIS method") Shows the ultimate value of drying shrinkage strain measured according to the standards.
(iii) The numerical value in the column "Measured value of strain after 6 months of drying" indicates the value of drying shrinkage strain (actually measured value) after 6 months of drying, measured in accordance with the JIS method (comparison example).
(iv) The numerical value in the column "Estimated value of strain after drying for 6 months" is, as an example, the final value of drying shrinkage strain with the coefficient selected from Table 1 according to the type of cement in the specimen. A value (estimated value) obtained by multiplying is shown (Example).
表3に示すように、本発明によれば、乾燥収縮ひずみの終局値に、供試体中のセメントの種類に応じて係数を乗じるだけで、JIS法に準拠して測定した乾燥期間6か月の乾燥収縮ひずみの値を、誤差が3.1%以内という高い精度で、労せず早期に推定できる。また、本発明の高い推定精度はセメントの種類に依らないため、汎用性が高い。 As shown in Table 3, according to the present invention, by simply multiplying the final value of the drying shrinkage strain by a coefficient according to the type of cement in the specimen, the drying period of 6 months measured in accordance with the JIS method The value of the drying shrinkage strain can be estimated at an early stage without much effort, with a high accuracy of within 3.1% error. Moreover, since the high estimation accuracy of the present invention does not depend on the type of cement, the versatility is high.
1 供試体
2 台座
4 レーザー変位計(ただし、黒色の矢印はレーザーを示す。)
5 支持部材
1
5 support member
Claims (5)
(A)2個以上のレーザー変位計、乾燥収縮ひずみ測定用の供試体を支持するための正三角形の3つの頂点または正方形の4つの頂点を形成するように配置してなる支持部材、および、該支持部材の一部を埋設してなる台座、を少なくとも含む、乾燥収縮ひずみ測定装置の前記支持部材上に、円板状または四角板状の供試体の中心が、前記支持部材が形成する正三角形または正方形の中心と一致するように載置する、供試体の載置工程
(B)該供試体の周囲の側面に、レーザー変位計からレーザーを照射して、レーザー変位計と供試体の周囲の側面の間の距離を測定し、該距離が一定に達した時点の供試体の乾燥収縮ひずみを、該供試体の乾燥収縮ひずみの終局値として取得する、乾燥収縮ひずみの終局値の取得工程
[表1]
The value obtained by multiplying the final value of the drying shrinkage strain obtained through the following steps (A) and (B) by a coefficient selected according to the type of cement described in Table 1, is JIS A 1129-1, JIS A 1129-2, or JIS A 1129-3, estimated as the value of drying shrinkage strain in a drying period of 6 months, method of estimating drying shrinkage strain (however, aggregate of concrete to be estimated and the aggregates of the following specimens are the same.) .
(A) two or more laser displacement gauges, a support member arranged to form three vertices of an equilateral triangle or four vertexes of a square for supporting a specimen for drying shrinkage strain measurement, and The center of a disk-shaped or square plate-shaped test piece is placed on the support member of the drying shrinkage strain measuring device, which includes at least a pedestal formed by embedding a part of the support member. (B) A step of placing the test piece so as to match the center of the triangle or square. A step of acquiring the final value of drying shrinkage strain, in which the distance between the sides of the specimen is measured, and the drying shrinkage strain of the specimen when the distance reaches a constant value is obtained as the ultimate value of the drying shrinkage strain of the specimen. [Table 1]
The method for estimating drying shrinkage strain according to any one of claims 1 to 4, wherein the test piece is dried while the test piece is placed on the support member.
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JP2012107994A (en) | 2010-11-17 | 2012-06-07 | Taiheiyo Cement Corp | Estimation method of drying shrinkage strain of concrete to which shrinkage suppressing material is added |
JP2014020866A (en) | 2012-07-17 | 2014-02-03 | Sumitomo Osaka Cement Co Ltd | Method for early estimating concrete drying shrinkage strain |
JP2018173400A (en) | 2017-01-16 | 2018-11-08 | 太平洋セメント株式会社 | Drying shrinkage strain measuring device, drying shrinkage measuring method, and drying shrinkage estimation method |
JP2018200293A (en) | 2017-05-26 | 2018-12-20 | 太平洋セメント株式会社 | Dry shrinkage distortion measurement device, dry shrinkage distortion measurement method, and dry shrinkage distortion estimation method |
JP2019020306A (en) | 2017-07-19 | 2019-02-07 | 太平洋セメント株式会社 | Method for predicting final value of drying shrinkage deformation of concrete |
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JP2012107994A (en) | 2010-11-17 | 2012-06-07 | Taiheiyo Cement Corp | Estimation method of drying shrinkage strain of concrete to which shrinkage suppressing material is added |
JP2014020866A (en) | 2012-07-17 | 2014-02-03 | Sumitomo Osaka Cement Co Ltd | Method for early estimating concrete drying shrinkage strain |
JP2018173400A (en) | 2017-01-16 | 2018-11-08 | 太平洋セメント株式会社 | Drying shrinkage strain measuring device, drying shrinkage measuring method, and drying shrinkage estimation method |
JP2018200293A (en) | 2017-05-26 | 2018-12-20 | 太平洋セメント株式会社 | Dry shrinkage distortion measurement device, dry shrinkage distortion measurement method, and dry shrinkage distortion estimation method |
JP2019020306A (en) | 2017-07-19 | 2019-02-07 | 太平洋セメント株式会社 | Method for predicting final value of drying shrinkage deformation of concrete |
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