JP3672526B2 - Method and apparatus for estimating strength of concrete - Google Patents

Description

【００２５】
上記の（３）式を変形することで、コンクリートの未中性化部分における反発度Ｒｉに関する演算式（次の（４）式）が得られる。
Ｒｉ＝β・Ｒｓ−(１−β)・ｂ／ａ …（４）
【００２６】
本願発明者等は、図２に示す中性化深さＣと表面硬度補正係数βの関係に基づき、図２に破線で示すように、中性化深さＣがＣ≦１[mm]の場合は表面硬度補正係数βとしてβ＝１を、中性化深さＣが１[mm]＜Ｃ≦５[mm]の場合には表面硬度補正係数βとしてβ＝0.5/Ｃ+0.5を、中性化深さＣがＣ＞５[mm]の場合には表面硬度補正係数βとしてβ＝0.6を各々用い、コンクリートの表面における反発度Ｒｓの測定結果から、上記の（４）式に従ってコンクリートの未中性化部分における反発度Ｒｉを求めた。そして、反発度Ｒｉとコンクリートの圧縮強度Ｆｃとの関係を回帰分析によって求めた（図３（Ｂ）参照）。その結果、
Ｆｃ[kgf/cm²]＝15.9Ｒｉ-246 …（５）
なる回帰式が得られ、相関係数ｒもｒ＝0.96と極めて高い値になった。
【００２７】
図３（Ａ）にはコンクリートの表面（中性化部分）における反発度Ｒｓとコンクリートの圧縮強度Ｆｃとの関係（相関係数ｒ＝0.61）を示すが、図３（Ｂ）を図３（Ａ）と比較しても明らかなように、コンクリートの未中性化部分における反発度Ｒｉ（図３（Ｂ）における修正反発度Ｒｉ）は、コンクリートの圧縮強度Ｆｃの推定に従来用いられていたコンクリートの表面における反発度Ｒｓと比較して、コンクリートの圧縮強度Ｆｃとの相関が非常に高く、コンクリートの圧縮強度Ｆｃを高い推定精度で推定できることが明らかである。
【００２８】
続いて本願発明者等は、コンクリートの表面における反発度Ｒｓを、表面硬度補正係数βを用いてコンクリートの内部（未中性化部分）における反発度に相当する修正反発度Ｒｉに補正した後に、この修正反発度Ｒｉからコンクリートの圧縮強度Ｆｃを推定する方法の有効性を確認するために、過去に実施された実験の実験データを用いて修正反発度Ｒｉの演算、及び修正反発度Ｒｉと圧縮強度Ｆｃの相関を確認する作業を行った。
【００２９】
上記過去の実験は、コンクリートの表面における反発度Ｒｓを測定する際のコンクリート表面に対する含水処理条件として、無処理（乾燥状態）、水噴霧、２４時間給水の３種類の処理条件を用意し、水／セメント比＝40％，55％，70％のコンクリート・ブロックを各々複数製作して屋外暴露の環境下におき、所定の材齢に達した時点で、水／セメント比が同一の各コンクリート・ブロックに対し、コンクリート表面に対する含水処理条件を互いに相違させて反発度Ｒｓを各々測定すると共に、前述した実験と同様に、圧縮試験機を用いたコンクリートの圧縮強度Ｆｃの測定及び中性化深さＣの測定を各々行ったものである。
【００３０】
図４（Ａ）には過去の実験によって得られたコンクリートの表面における反発度Ｒｓとコンクリートの圧縮強度Ｆｃとの関係を示し、図４（Ｂ）には、中性化深さＣに対応する表面硬度補正係数βを用い、前出の（４）式に従って反発度Ｒｓから演算した修正反発度Ｒｉとコンクリートの圧縮強度Ｆｃとの関係を示す。図４（Ｂ）を図４（Ａ）と比較しても明らかなように、反発度Ｒｓに代えて修正反発度Ｒｉを用いることで、コンクリートの圧縮強度Ｆｃとの相関係数ｒは0.36→0.76と大幅に向上することが確認された。
【００３１】
本願発明者等は、前述した実験及び過去の実験データを用いた確認作業の結果に基づき、コンクリートの表面における反発度Ｒｓを、コンクリートの表面部（中性化している部分）の硬さ（押込硬さ）とコンクリートの内部（中性化していない部分）の硬さ（押込硬さ）との関係に基づいて補正した後に、補正後の反発度Ｒｉに基づいてコンクリートの圧縮強度Ｆｃを推定すれば、コンクリートの圧縮強度Ｆｃを高精度に推定できるとの知見を得た。
【００３２】
上記に基づき請求項１記載の発明に係るコンクリートの強度推定方法は、圧縮強度の推定対象のコンクリートの表面部の反発度Ｒｓをコンクリート・テスト・ハンマを用いて測定し、表面部が中性化しているコンクリートにおける表面部（中性化している部分）の硬さと中性化していない内部の硬さとの関係に基づいて、推定対象のコンクリートの表面部の反発度Ｒｓを補正し、補正後の反発度Ｒｉに基づいて推定対象のコンクリートの圧縮強度を推定するので、上述した実験結果からも明らかなように、推定対象のコンクリートの表面部が中性化していたとしても、その影響を受けることなく、推定対象のコンクリートの圧縮強度を高精度に推定することができる。
【００３３】
また、請求項１記載の発明では、コンクリート・テスト・ハンマを用いて測定した推定対象のコンクリートの表面部の反発度Ｒｓから、推定対象のコンクリートの圧縮強度を推定することができるので、圧縮強度Ｆｃを圧縮試験機によって直接測定する場合のように建造物からコンクリートを採取する必要もなく、非破壊的な試験方法によりコンクリートの圧縮強度を推定することができる。
【００３４】
なお、請求項１記載の発明において、表面部が中性化しているコンクリートにおける表面部の硬さと内部の硬さとの関係としては、例えば請求項２に記載したように、表面部が中性化しているコンクリートにおける表面部の硬さと内部の硬さの比率に相当する表面硬度補正係数βを用いることができる。また、この表面硬度補正係数βに代えて、コンクリートの表面部の硬さ及び内部の硬さに応じて値が変化する任意のパラメータを用いることも可能である。
【００３５】
ところで、請求項２に記載した表面硬度補正係数βは、先に説明した図２からも明らかなようにコンクリートの中性化深さと相関があり、コンクリートの中性化深さに応じて値が変化する。このため、請求項２記載の発明のように、表面部の硬さと内部の硬さとの関係として表面硬度補正係数βを用いる場合には、請求項３に記載したように、表面硬度補正係数βを、表面部が中性化しているコンクリートにおける中性化深さと関係付けておき、推定対象のコンクリートの中性化深さを測定し、推定対象のコンクリートの中性化深さに対応する表面硬度補正係数βを用いて、推定対象のコンクリートの表面部の反発度Ｒｓを補正することが好ましい。
【００３６】
これにより、圧縮強度の推定対象のコンクリートの中性化深さがばらついている場合にも、表面硬度補正係数βとして、前記推定対象のコンクリートの中性化深さに対応する値、すなわち推定対象のコンクリートの表面部の硬さと内部の硬さの比率を精度良く表す値が用いられ、この表面硬度補正係数βを用いて表面部の反発度Ｒｓが補正され、コンクリートの圧縮強度が推定されることになるので、コンクリートの圧縮強度の推定精度を更に向上させることができる。
【００３７】
なお、推定対象のコンクリートの中性化深さを測定するためには、中性化していない部分に到達する深さまで推定対象のコンクリートを削り取る必要がある。しかしながら、コンクリートの中性化は、コンクリートがおかれている暴露環境における空気中の炭酸ガスとコンクリートが反応することが原因であり、中性化部分はコンクリートの表面から徐々に内部へ進行していくが、既往の中性化速度式（岸谷式等）によると、水／セメント比が60％のコンクリートの屋外暴露環境下で経過年数が１００年でもコンクリートの中性化深さは30mm〜40mmである。水／セメント比が60％より小さい場合や経過年数が少ない場合は、コンクリートの中性化深さはこれより小さい。
【００３８】
このため、建造物のコンクリートの圧縮強度Ｆｃを推定するために、建造物のコンクリートの中性化深さを測定する場合にも、圧縮強度Ｆｃを圧縮試験機によって直接測定するためにコンクリート・コアを採取する場合と比較して、中性化していない部分に到達するために建造物から削り取るべきコンクリートの量はごく僅かであり、中性化深さの測定（圧縮強度Ｆｃの推定）のためにコンクリートを削り取ることで建造物に影響を及ぼすことは殆どない。
【００３９】
また、請求項３に記載した表面硬度補正係数βとコンクリートの中性化深さの関係付けは、例えば請求項４に記載したように、推定対象のコンクリートの中性化深さＣがＣ≦１[mm]の場合には表面硬度補正係数βとしてβ＝１を用い、中性化深さＣが１[mm]＜Ｃ≦５[mm]の場合には表面硬度補正係数βとしてβ＝0.5/Ｃ+0.5を用い、中性化深さＣがＣ＞５[mm]の場合には表面硬度補正係数βとしてβ＝0.6を用いるように行うことができる。請求項４に記載した中性化深さＣと表面硬度補正係数βとの関係は本願発明者等が実験結果から導き出した関係であり、推定対象のコンクリートの圧縮強度の推定精度を更に向上させることができる。
【００４０】
また、請求項２記載の発明のように、表面部の硬さと内部の硬さとの関係として表面硬度補正係数βを用いる場合、例えば請求項５に記載したように、推定対象のコンクリートの内部の反発度に相当する修正反発度Ｒｉを、表面硬度補正係数βを用いて、
Ｒｉ＝β・Ｒｓ−(１−β)・ｂ／ａ
なる演算式（但しａ及びｂは定数）によって演算することで、推定対象のコンクリートの表面部の反発度Ｒｓを補正することができる。また、上記の演算式の定数ａ，ｂとしては、例えば請求項６に記載したようにａ＝1.82、ｂ＝-36.2を用いることができる。
【００４１】
請求項５に記載の演算式及び請求項６に記載の定数ａ，ｂの値は、何れも本願発明者等が実験結果から導き出したものであるので、上記の演算式及び定数ａ，ｂの値を用いることにより、先に説明した実験結果と同様に、高い推定精度で推定対象のコンクリートの圧縮強度を推定することができる。
【００４２】
ところで、図４（Ｂ）に示す結果を参照しても明らかなように、特に水／セメント比＝70％のコンクリートのデータについては、（５）式の回帰式を表す直線との偏差が大きいデータも多く、修正反発度Ｒｉからの圧縮強度Ｆｃの推定精度が比較的低いことが理解できる。本願発明者等は、上記現象はコンクリート表面に対する含水処理条件が影響しているのではないかと考え、図４（Ｂ）に示す結果を含水処理条件（無処理、水噴霧、２４時間給水）毎に分け、修正反発度Ｒｉと圧縮強度Ｆｃの関係を含水処理条件毎に回帰分析によって求めた。結果を図５に示す。
【００４３】
それぞれの含水処理条件毎のコンクリート表面の含水量は（無処理＜水噴霧＜２４時間給水）であり、図５の（Ａ）〜（Ｃ）を相互に比較しても明らかなように、コンクリート表面の反発度を測定する際のコンクリート表面の含水量が多くなるに従って、修正反発度Ｒｉと圧縮強度Ｆｃとの相関が高く（相関係数ｒの値が高く）なっており、特に水／セメント比＝70％のコンクリートのデータについては、コンクリート表面の含水量が多くなるに従って回帰式を表す直線との偏差が小さくなっていることが理解できる。
【００４４】
このため、請求項１記載の発明において、例えば請求項７に記載したように、圧縮強度の推定対象のコンクリートの表面部の反発度をコンクリート・テスト・ハンマを用いて測定するに際し、反発度を測定する推定対象のコンクリートの表面部を湿潤状態にすることが好ましい。これにより、上述した実験結果からも明らかなように、コンクリートの圧縮強度の推定精度を更に向上させることができる。
【００４５】
また、図５（Ａ）〜（Ｃ）にそれぞれ示す実験データにおける測定条件の相違は、コンクリート・テスト・ハンマを用いてコンクリートの表面部の反発度Ｒｓを測定する際の含水処理条件のみであり、表面部の反発度Ｒｓから修正反発度Ｒｉへの補正が線形変換であることを考えると、コンクリート表面部の反発度Ｒｓを修正反発度Ｒｉへ補正することなく、反発度Ｒｓから圧縮強度Ｆｃを直接推定する場合にも、コンクリートの表面部の反発度Ｒｓを測定する際にコンクリートの表面部を湿潤状態にしておけば、圧縮強度Ｆｃの推定精度が向上することは容易に推察できる。
【００４７】
なお、請求項７記載の発明において、コンクリートの表面部を湿潤状態にするに際しては、例えば請求項８に記載したように、推定対象のコンクリートの表面部に水を噴霧するか、又は所定時間以上給水することで行うことができる。また、図５（Ａ）〜（Ｃ）に示す実験結果から、コンクリート表面の反発度を測定する際のコンクリート表面の含水量を多くした方がコンクリートの圧縮強度の推定精度が向上することが明らかであるので、コンクリートの表面部を湿潤状態にする際には、コンクリートの表面部の含水量がなるべく多くなるように、コンクリートの表面部に、望ましくは１０分以上、より望ましくは１時間以上給水することが好ましい。
【００４８】
請求項９記載の発明に係るコンクリートの強度推定装置は、コンクリート・テスト・ハンマを用いて測定された圧縮強度の推定対象のコンクリートの表面部の反発度を、表面部が中性化しているコンクリートにおける前記表面部の硬さと中性化していない内部の硬さとの関係に基づいて補正する補正手段と、前記補正手段による補正後の反発度に基づいて前記推定対象のコンクリートの圧縮強度を推定する推定手段と、を含んで構成されているので、請求項１記載の発明と同様に、非破壊的な試験方法により、コンクリートの圧縮強度を高精度に推定することができる。
【００４９】
また、請求項９記載の発明において、例えば請求項１０に記載したように、表面部の硬さと内部の硬さとの関係として、表面部が中性化しているコンクリートにおける表面部の硬さと内部の硬さの比率に相当する表面硬度補正係数βを、表面部が中性化しているコンクリートにおける中性化深さと関係付けて記憶する記憶手段と、推定対象のコンクリートの中性化深さを測定可能な測定手段を更に設け、補正手段は、前記測定手段によって測定された推定対象のコンクリートの中性化深さに対応する表面硬度補正係数βを用いて、推定対象のコンクリートの表面部の反発度を補正するように構成することが好ましい。これにより、請求項３記載の発明と同様に、推定対象のコンクリートの圧縮強度の推定精度を更に向上させることができる。
【００５０】
また、コンクリートの中性化深さの測定は、例えばコンクリートからコンクリート・コアを採取し、採取したコンクリート・コアの側面に試薬を塗布し、変色が発生した領域を確認する等によって行うことも可能ではあるが、作業が非常に煩雑であるという問題がある。このため、請求項１０記載の発明に係る測定手段は、例えば請求項１１に記載したように、コンクリートに孔を穿設可能な穿孔手段と、前記穿孔手段による孔の穿設に伴って生ずるコンクリート粉に試薬を供給する供給手段と、前記供給手段によって供給された試薬により前記コンクリート粉に色変化が生じたか否かを検出する検出手段と、を含んで構成することが好ましい。
【００５１】
請求項１１記載の発明では、コンクリートへの孔の穿設に伴って生ずるコンクリート粉に試薬（例えばフェノールフタレイン溶液等）を供給し、コンクリート粉に色変化が生じたか否かを検出するので、検出手段による検出結果が変化したときに、穿孔手段によって穿設された孔の深さが、コンクリートのうち中性化している部分と中性化していない部分の境界に達したと判断することができ、そのときの孔の深さを測定することで、中性化深さを測定することができる。
【００５２】
従って、コンクリートからコンクリート・コアを採取したり、採取したコンクリート・コアの側面に試薬を塗布する等の作業が不要となるので、中性化深さの測定を容易に行うことができる。また、検出手段による検出結果が変化したときの孔の深さを検知する検知手段を更に設ければ、中性化深さを測定するための作業を更に簡略化できる。
【００５３】
【発明の実施の形態】
以下、図面を参照して本発明の実施形態の一例を詳細に説明する。図６には本実施形態に係る強度推定装置１０が示されている。なお、強度推定装置１０は本発明に係るコンクリートの強度推定装置に対応している。
【００５４】
強度推定装置１０は装置本体１２を備えており、この装置本体１２は、ＣＰＵ，ＲＯＭ，ＲＡＭ，入出力ポートがバスを介して互いに接続されて成るマイクロコンピュータを内蔵し、任意の情報を表示可能なディスプレイ１２Ａを含んで構成されている。なお、装置本体１２は請求項９に記載の補正手段及び推定手段としての機能を備えており、ＲＯＭは請求項１０に記載の記憶手段に対応している。装置本体１２には、コンクリート表面の反発度Ｒｓを測定するためのコンクリート・テスト・ハンマ１４と、コンクリートの中性化深さＣを測定するための中性化深さ測定機１６が通信線を介して各々接続されている。なお、中性化深さ測定機１６は請求項１０に記載の測定手段に対応している。
【００５５】
コンクリート・テスト・ハンマ１４としては、公知の種々の構成の中から任意の構成を採用可能であり、例えば図示は省略するが、測定時に先端部がコンクリートの測定面に当接されるプランジャ１８が本体１４Ａから突出するように設けられていると共に、本体１４Ａには、プランジャ１８を打撃するためのハンマと、ハンマを所定位置に保持する保持機構が内蔵されており、プランジャ１８の先端部がコンクリートの測定面に当接された状態で本体１４Ａがコンクリート側へ向けて押圧され、プランジャ１８が本体１４Ａ内に所定量押込まれると、保持機構によるハンマの保持が解除されてハンマがプランジャ１８を介してコンクリートの表面を打撃し、コンクリート表面の反発度Ｒｓに応じて跳ね返るプランジャ１８の跳ね返り量を計測することで、コンクリート表面の反発度Ｒｓを測定する構成を採用することができる。
【００５６】
本実施形態に係るコンクリート・テスト・ハンマ１４は、プランジャ１８の跳ね返り量を計測するセンサと、該センサによって計測された跳ね返り量を所定の演算式に従ってコンクリート表面の反発度Ｒｓに換算し、通信線を介して装置本体１２へ反発度Ｒｓの測定値を送信する信号処理回路を内蔵している。
【００５７】
一方、図７に示すように、中性化深さ測定機１６は、本体１６Ａに内蔵されたフレーム２０に、所定値以上の厚みの底を有する有底円筒状の回転体２２が一対のベアリング２４を介して回転可能に支持されている。回転体２２の外周部のうち一対のベアリング２４の間に相当する箇所にはマグネット２６が取付けられており、フレーム２０には、マグネット２６に対応する位置に、マグネット２６と間隙を隔てて励磁コイル２８が取り付けられている。従って、回転体２２は励磁コイル２８が通電されることで回転される。
【００５８】
回転体２２の軸線に沿った一端側（開口２２Ａが形成されている側と反対側）には小径の円孔３０が穿設されており、円孔３０の内壁には、カートリッジ３２を螺入するための雌ねじ（逆ねじ）が形成されている。カートリッジ３２は中空で全体として略円柱状とされ、軸線に沿った一端部に孔が穿設されており、この孔の周囲に、カートリッジ３２本体と同軸に円筒状のリブ３２Ａが立設されている。リブ３２Ａの外周には雄ねじ（逆ねじ）が形成されている。これにより、カートリッジ３２（のリブ３２Ａ）が回転体２２（の円孔３０）に螺入された状態で、カートリッジ３２は回転体２２と一体に回転される。
【００５９】
カートリッジ３２の内部には、フェノールフタレイン溶液等の試薬を貯留するための貯留部が形成されていると共に、貯留部に空気を送り込むことで貯留部に貯留された試薬に圧力を加えることが可能な加圧機構が設けられている（何れも図示省略）。回転体２２の円孔３０の底部にはＯリング３４が取り付けられており、カートリッジ３２が螺入された状態で、カートリッジ３２のリブ３２ＡはＯリング３４を介して円孔３０の底部に密着される。
【００６０】
また回転体２２には、試薬が通過するための通路３６が軸線に沿って形成されており、通路３６の一端は円孔３０の底部中央に開口しており、他端は開口２２Ａの底部中央に開口している。そして通路３６の途中にはバルブ３８が設けられている。このバルブ３８は図示しないリンク機構と連結されており、回転体２２の回転と連動して開閉され、詳しくは、回転体２２の回転が停止しているときにはバルブ３８が閉止され、回転体２２が回転しているときにはバルブ３８が開放されるようになっている。
【００６１】
回転体２２の軸線に沿った他端側（開口２２Ａが形成されている側）には、ドリルビット４０を把持するための複数のチャック４２が開口２２Ａの内側に配置されており、この複数のチャック４２は、チャック４２相互の間隔を変更可能なギア機構（図示省略）を介して回転体２２に支持されている。複数のチャック４２は、開口２２Ａにドリルビット４０の基部が挿入された状態で、チャック４２相互の間隔が小さくなるようにギア機構のギアが図示しない工具によって回転されることで、ドリルビット４０を回転体２２と同軸となる位置に位置決めして把持する。これにより、ドリルビット４０は回転体２２と一体に回転される。
【００６２】
中性化深さ測定機１６に使用されるドリルビット４０は、コンクリートへの穿孔に十分な強度を有する金属材から成り、外周に螺旋状の溝４４が形成されている。ドリルビット４０は、測定対象のコンクリートの中性化深さＣを測定する際に、測定対象のコンクリートに孔を穿設するために用いられる。また、ドリルビット４０は、ドリルビット４０の軸線に沿ってドリルビット４０を貫く孔４６が形成されており、孔４６はドリルビット４０の先端部で複数に分岐され、各々ドリルビット４０の先端付近の互いに異なる位置に貫通している。
【００６３】
一方、開口２２Ａの底部にはＯリング４８が取り付けられており、ドリルビット４０の基部側が、ドリルビット４０の底面が開口２２Ａの底面に突き当たる位置まで開口２２Ａに挿入され、複数のチャック４２によってドリルビット４０が把持された状態で、ドリルビット４０の底面はＯリング４８を介して開口２２Ａの底部に密着される。
【００６４】
これにより、貯留部に試薬が貯留されたカートリッジ３２が円孔３０に螺入され、加圧機構によって貯留部が加圧されると、貯留部内の試薬は、カートリッジ３２から噴出して通路３６へ流入し、バルブ３８配設位置に到達し、回転体２２が回転されることでバルブ３８が開放されると、通路３６からドリルビット４０の孔４６内に流入して孔４６を通過し、ドリルビット４０の先端付近の複数箇所から噴出することになる。
【００６５】
また、中性化深さ測定機１６の本体１６Ａには、本体１６Ａ（回転体２２）に取り付けられたドリルビット４０と同一方向に突出するように、穿孔深さスケール５０及び色変化検出部５２が取り付けられている。
【００６６】
穿孔深さスケール５０は、図７矢印Ａ方向（本体１６Ａに収納される方向）及びその逆の方向（本体１６Ａから突出する方向）にスライド移動可能とされており、測定対象のコンクリートの中性化深さＣを測定する際には、本体１６Ａからの突出量がドリルビット４０と同一となる測定開始位置（図７に示す位置）までスライド移動される。また、ドリルビット４０が測定対象のコンクリートに孔を穿設している間、穿設された孔の深さの増大に伴って穿孔深さスケール５０の先端部が測定対象のコンクリートの表面により押圧され、穿孔深さスケール５０は図７矢印Ａ方向にスライド移動される。なお、本体１６Ａ内には、測定開始位置からの穿孔深さスケール５０のスライド量を検出するセンサが設けられている。
【００６７】
また、色変化検出部５２は外形が略Ｌ字状で、先端部がドリルビット４０を向くように取り付けられており、先端部には、ドリルビット４０へ向けて光を射出する発光素子と、発光素子から射出されてドリルビット４０で反射された光を受光する受光素子が内蔵され、受光素子は信号処理回路に接続されている（何れも図示省略）。
【００６８】
中性化深さＣを測定する際にはドリルビット４０によって測定対象のコンクリートに孔が穿設されるが、このとき同時にドリルビット４０の先端付近の複数箇所から試薬が噴出するので、孔の穿設に伴って生ずるコンクリート粉は、試薬と混合された状態でドリルビット４０の溝４４に付着して孔から排出されることになる。従って、溝４４に付着して排出されるコンクリート粉は、中性化していれば色が変化せず、中性化していなければ試薬と反応して紅色に変化する。このため、受光素子に接続された信号処理回路は、受光素子から入力された信号に基づいて、溝４４に付着して排出されるコンクリート粉が紅色に変化したか否かを判断し、紅色に変化したと判断した場合に信号を出力する。
【００６９】
色変化検出部５２の信号処理回路は制御回路（図示省略）に接続されており、図示しないスイッチがオンされる等により中性化深さＣの測定が指示されると、励磁コイル２８に通電することで回転体２２（及びドリルビット４０）を回転させ（この回転に伴いバルブ３８が開放され、ドリルビット４０の先端付近から試薬が噴出する）、溝４４に付着して排出されるコンクリート粉が紅色に変化したことを表す信号が信号処理回路から入力されると、励磁コイル２８への通電を停止して回転体２２（及びドリルビット４０）の回転を停止させる。
【００７０】
また、制御回路には穿孔深さスケール５０のスライド量を検出するセンサが接続されており、回転体２２（及びドリルビット４０）の回転を停止させた際のセンサ出力に基づき、穿孔深さスケール５０のスライド量（ドリルビット４０によって穿設された孔の深さ）、すなわち中性化深さＣの測定値を、通信線を介して装置本体１２へ送信する。
【００７１】
なお、上述した中性化深さ測定機１６のうち、ドリルビット４０は請求項１１に記載の穿孔手段に、カートリッジ３２（加圧機構）、通路３６、バルブ３８及びドリルビット４０の孔４６は請求項１１に記載の供給手段に、色変化検出部５２は請求項１１に記載の検出手段に各々対応しており、穿孔深さスケール５０及び該穿孔深さスケール５０のスライド量を検出するセンサは、検出手段による検出結果が変化したときの孔の深さを検知する検知手段として機能する。
【００７２】
一方、装置本体１２のＲＯＭには、表面硬度補正係数βが中性化深さＣと関係付けられて予め記憶されており、詳しくは以下の（６）式が記憶されている。
【００７３】

また、装置本体１２のＲＯＭには、コンクリート表面の反発度Ｒｓから修正反発度Ｒｉを推定演算するための演算式（次の（７))式が予め記憶されている。
Ｒｉ＝β・Ｒｓ−(１−β)・-36.2／1.82 …（７）
【００７４】
更に、装置本体１２のＲＯＭには、修正反発度Ｒｉからコンクリートの圧縮強度Ｆｃを推定演算するための演算式（次の（８))式が予め記憶されている。
Ｆｃ＝ｄ・Ｒｉ−ｅ …（８）
なお（８）式における定数ｄ，ｅの値は、修正反発度Ｒｉから圧縮強度Ｆｃを精度良く推定演算可能な値であればよい。後述するように、本実施形態では、圧縮強度Ｆｃの推定精度を向上させるため、反発度Ｒｓを測定するコンクリートの表面に事前に給水し、コンクリート表面の含水量を増大させた後に反発度Ｒｓの測定を行うが、図５（Ａ）〜（Ｃ）に示す回帰式からも明らかなように、相関係数ｒが最小となる回帰式の定数ｄ，ｅの値は、コンクリート表面への給水条件（含水処理条件）によって相違している。このため、（８）式の定数ｄ，ｅの値としては、反発度Ｒｓの測定に際して行う給水の条件（含水処理条件）に対応する値を用いればよい。
【００７５】
次に本実施形態の作用として、強度推定装置１０を用いて建造物のコンクリートの圧縮強度Ｆｃを調査する際の作業者の作業及び強度推定装置１０で行われる処理について、図８を参照して説明する。
【００７６】
建造物のコンクリートの圧縮強度Ｆｃを調査する場合、作業者は、まず対象となる建造物のうち、圧縮強度Ｆｃを調査したい箇所（表面の反発度Ｒｓ及び中性化深さＣを測定すべき箇所）を選定し（ステップ７０）、選定した測定箇所に給水することで測定個所のコンクリートの表面の含水量を増大させる（ステップ７０）。なお、この給水は、単に水を噴霧するのみでもよいが、圧縮強度Ｆｃの推定精度向上が目的であるので、望ましくは１０分以上、更に望ましくは１時間以上給水することで、コンクリート表面の含水量を大幅に増大させて所定値以上とすることが好ましい。
【００７７】
測定個所への給水が完了すると、作業者は、強度推定装置１０の電源を投入する等により強度推定装置１０を起動する（ステップ７４）。これにより、強度推定装置１０の装置本体１２で強度推定処理が実行され、ステップ８０では、測定個所のコンクリート表面の反発度Ｒｓの測定を要請するメッセージをディスプレイ１２Ａに表示する等により、反発度Ｒｓの測定を作業者に要請する。また、次のステップ８２ではコンクリート・テスト・ハンマ１４から反発度Ｒｓの測定データが入力されたか否か判定し、判定が肯定される迄ステップ８２を繰り返す。
【００７８】
ディスプレイ１２Ａに表示されたメッセージを確認すると、作業者は、コンクリート・テスト・ハンマ１４を用いて測定個所のコンクリート表面の反発度Ｒｓを測定する作業を行う（ステップ７６）。すなわち、コンクリート・テスト・ハンマ１４のハンマが保持機構によって所定位置に保持されている状態で、プランジャ１８の先端部が測定個所のコンクリート表面に当接するようにコンクリート・テスト・ハンマ１４を保持し、更にプランジャ１８が本体１４Ａ内に所定量押込まれるように、本体１４Ａをコンクリート側へ向けて押圧する。
【００７９】
これにより、保持機構によるハンマの保持が解除されることでハンマがプランジャ１８を介してコンクリートの表面を打撃し、コンクリート表面の反発度Ｒｓに応じて跳ね返るプランジャ１８の跳ね返り量がセンサによって計測される。センサによって計測された跳ね返り量は信号処理回路によってコンクリート表面の反発度Ｒｓに換算され、通信線を介し反発度Ｒｓの測定データとして装置本体１２へ送信される。
【００８０】
コンクリート・テスト・ハンマ１４からコンクリート表面の反発度Ｒｓの測定データを受信すると、装置本体１２では、ステップ８２の判定が肯定されてステップ８４へ移行し、測定個所のコンクリートの中性化深さＣの測定を要請するメッセージをディスプレイ１２Ａに表示する等により、中性化深さＣの測定を作業者に要請する。また、次のステップ８６では中性化深さ測定機１６から中性化深さＣの測定データが入力されたか否か判定し、判定が肯定される迄ステップ８６を繰り返す。
【００８１】
ディスプレイ１２Ａに表示されたメッセージを確認すると、作業者は、中性化深さ測定機１６を用いて測定個所のコンクリートの中性化深さＣを測定する作業を行う（ステップ７８）。すなわち、まず準備作業として、中性化深さ測定機１６にドリルビット４０が取り付けられているか否かを確認し、ドリルビット４０が取り付けられていなければドリルビット４０の取り付けを行う。次に本体１６Ａにカートリッジ３２が装填されているか否か確認し、未装填であればカートリッジ３２の装填（円孔３０への螺入）を行い、続いてカートリッジ３２に設けられている加圧機構を操作してカートリッジ３２の貯留部への加圧を行う。更に、穿孔深さスケール５０を本体１６Ａから引き出して測定開始位置までスライド移動させる。そして、上述した準備作業が完了すると、ドリルビット４０の先端部が測定個所のコンクリート表面に当接し、ドリルビット４０がコンクリート表面に対して垂直となるように本体１６Ａを保持し、この状態を維持したまま図示しないスイッチをオンすることで中性化深さＣの測定開始を指示する。
【００８２】
これにより、ドリルビット４０が回転して測定個所のコンクリートへの穿孔が開始されると共に、ドリルビット４０の先端付近から試薬が噴出し、溝４４に付着して排出されるコンクリート粉が紅色に変化したことを色変化検出部５２によって検出されると（すなわちドリルビット４０によって穿設される孔が、測定個所のコンクリートの未中性化部分に達すると）、ドリルビット４０の回転が停止され、穿孔深さスケール５０のスライド量が、通信線を介し中性化深さＣの測定データとして装置本体１２へ送信される。
【００８３】
中性化深さ測定機１６から中性化深さＣの測定データを受信すると、装置本体１２では、ステップ８６の判定が肯定されてステップ８８へ移行し、中性化深さ測定機１６から受信した測定データが表す中性化深さＣをＲＯＭに記憶されている（６）式と比較し、１[mm]＜中性化深さＣ≦５[mm]の場合には表面硬度補正係数βを演算することで、表面硬度補正係数βとして、測定個所のコンクリートの中性化深さＣに対応する値を設定する。
【００８４】
次のステップ９０では、ステップ８８で求めた表面硬度補正係数β、コンクリート・テスト・ハンマ１４から受信した測定データが表す反発度Ｒｓを、ＲＯＭに記憶されている（７）式に各々代入することで、測定個所のコンクリート内部（中性化していない部分）の反発度に相当する修正反発度Ｒｉを演算する。またステップ９２では、ステップ９０で求めた修正反発度Ｒｉを、ＲＯＭに記憶されている（８）式に代入することで、測定個所のコンクリートの圧縮強度Ｆｃを推定演算する。そしてステップ９４では、ステップ９２の推定演算によって得られた圧縮強度Ｆｃの推定値をディスプレイ１２Ａに表示させる等によって出力する。
【００８５】
このように、本実施形態では、測定個所のコンクリート表面の反発度Ｒｓ及び中性化深さＣを測定した後に、表面硬度補正係数βとして、測定個所のコンクリートの中性化深さＣに対応する値を用いて、コンクリート表面の反発度Ｒｓをコンクリートの内部の反発度に相当する修正反発度Ｒｉに補正し、修正反発度Ｒｉからコンクリートの圧縮強度Ｆｃを推定演算しているので、コンクリート表面の中性化の影響を受けることなく、コンクリートの実際の圧縮強度Ｆｃを精度良く表す圧縮強度Ｆｃの推定値を得ることができる。
【００８６】
また、コンクリート・テスト・ハンマ１４を用いた反発度Ｒｓの測定はコンクリートの表面を打撃するのみであり、中性化深さ測定機１６を用いた中性化深さＣの測定も中性化していない部分が出現するまで孔を穿設するのみであるので、圧縮強度Ｆｃの推定のために建造物等からコンクリート・コアを採取する必要はなく、圧縮試験機によって圧縮強度Ｆｃを直接測定する場合と比較して、建造物に与える影響を非常に小さくすることができる。
【００８７】
なお、上記では中性化深さＣと表面硬度補正係数βの関係付けの一例として、中性化深さＣの数値範囲を複数のクラスに分け、表面硬度補正係数βを規定する数式を各クラス毎に設定する例((６）式参照）を説明したが、これに限定されるものではなく、中性化深さＣと表面硬度補正係数βの関係を単一の数式で表したり、テーブル等の形態で表すことで中性化深さＣと表面硬度補正係数βを関係付け、上記の単一の数式又はテーブル等を用いることで中性化深さＣから表面硬度補正係数βを求めるようにしてもよい。
【００８８】
また、コンクリート表面の反発度Ｒｓと表面硬度補正係数βから修正反発度Ｒｉを求める場合や、修正反発度Ｒｉからコンクリートの圧縮強度Ｆｃを求める場合についても、（７）式や（８）式のような演算式を用いることに限定されるものではなく、テーブル等を用いて行う（例えば修正反発度Ｒｉを求める場合には２次元ルックアップテーブルが好適である）ことも可能である。
【００８９】
また、上記では本発明に係るコンクリートの強度推定装置の一例として、コンクリート・テスト・ハンマ１４及び中性化深さ測定機１６と装置本体１２が通信線で接続された構成の強度推定装置１０を説明したが、これに限定されるものではなく、コンクリート・テスト・ハンマ１４や中性化深さ測定機１６によって測定された測定値を、作業者が手入力で装置本体１２に入力する構成であってもよい。
【００９０】
【発明の効果】
以上説明したように請求項１記載の発明は、コンクリート・テスト・ハンマを用いて測定した圧縮強度の推定対象のコンクリートの表面部の反発度を、表面部が中性化しているコンクリートにおける表面部の硬さと中性化していない内部の硬さとの関係に基づいて補正し、補正後の反発度に基づいてコンクリートの圧縮強度を推定するので、非破壊的な試験方法により、コンクリートの圧縮強度を高精度に推定できる、という優れた効果を有する。
【００９１】
請求項３記載の発明は、請求項２記載の発明において、表面部の硬さと内部の硬さとの関係としての表面硬度補正係数βを、表面部が中性化しているコンクリートにおける中性化深さと関係付けておき、推定対象のコンクリートの中性化深さに対応する表面硬度補正係数βを用いてコンクリートの表面部の反発度を補正するので、上記効果に加え、コンクリートの圧縮強度の推定精度を更に向上させることができる、という効果を有する。
【００９２】
請求項７記載の発明は、請求項１記載の発明において、コンクリートの表面部の反発度をコンクリート・テスト・ハンマを用いて測定する際に、コンクリートの表面部を湿潤状態にするので、上記効果に加え、コンクリートの圧縮強度の推定精度を更に向上させることができる、という効果を有する。
【００９４】
請求項９記載の発明は、コンクリート・テスト・ハンマを用いて測定された圧縮強度の推定対象のコンクリートの表面部の反発度を、表面部が中性化しているコンクリートにおける表面部の硬さと中性化していない内部の硬さとの関係に基づいて補正する補正手段と、補正後の反発度に基づいてコンクリートの圧縮強度を推定する推定手段と、を含んで構成したので、非破壊的な試験方法により、コンクリートの圧縮強度を高精度に推定することができる、という優れた効果を有する。
【００９５】
請求項１０記載の発明は、請求項９記載の発明において、表面部が中性化しているコンクリートにおける中性化深さと関係付けて表面硬度補正係数βを記憶する記憶手段と、コンクリートの中性化深さを測定可能な測定手段を更に設け、補正手段は、測定された推定対象のコンクリートの中性化深さに対応する表面硬度補正係数βを用いて、推定対象のコンクリートの表面部の反発度を補正するので、上記効果に加え、推定対象のコンクリートの圧縮強度の推定精度を更に向上させることができる、という効果を有する。
【００９６】
請求項１１記載の発明は、請求項１０記載の発明において、測定手段を、コンクリートに孔を穿設可能な穿孔手段と、孔の穿設に伴って生ずるコンクリート粉に試薬を供給する供給手段と、供給された試薬によりコンクリート粉に色変化が生じたか否かを検出する検出手段と、を含んで構成したので、上記効果に加え、中性化深さの測定を容易に行うことができる、という効果を有する。
【図面の簡単な説明】
【図１】 本願発明者等が実施した実験によって得られた、コンクリートの表面における反発度Ｒｓとコンクリートの表面から深さ1mmの位置におけるヴィッカース硬さＨｓとの関係を示す線図である。
【図２】 本願発明者等が実施した実験によって得られた、中性化深さＣと表面硬度補正係数βとの関係を示す線図である。
【図３】 本願発明者等が実施した実験によって得られた、（Ａ）はコンクリート表面における反発度Ｒｓと圧縮強度Ｆｃの関係、（Ｂ）はコンクリート内部における反発度の推定値（修正反発度Ｒｉ）と圧縮強度Ｆｃの関係を各々示す線図である。
【図４】 （Ａ）は他の実験によって得られたコンクリート表面における反発度Ｒｓと圧縮強度Ｆｃの関係、（Ｂ）は（Ａ）の反発度Ｒｓから推定演算したコンクリート内部における反発度の推定値（修正反発度Ｒｉ）と圧縮強度Ｆｃの関係を各々示す線図である。
【図５】 （Ａ）〜（Ｃ）は、本願発明者等が実施した実験によって得られた修正反発度Ｒｉと圧縮強度Ｆｃの関係を、コンクリート表面に対する含水処理条件毎に示す線図である。
【図６】 本実施形態に係る強度推定装置の概略構成図である。
【図７】 中性化深さ測定機の概略構成を一部破断して示す概略図である。
【図８】 コンクリートの圧縮強度の推定にあたり、作業者によって行われる作業及び強度推定装置によって行われる処理を示すフローチャートである。
【図９】 反発度Ｒｓから圧縮強度Ｆｃを推定する従来の方法における推定精度を説明するための線図である。
【符号の説明】
１０ 強度推定装置
１２ 装置本体
１４ コンクリート・テスト・ハンマ
１６ 中性化深さ測定機[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a concrete strength estimation method and apparatus, and more particularly, to a concrete strength estimation method for estimating the compressive strength Fc of concrete, and a concrete strength estimation apparatus to which the concrete strength estimation method can be applied.
[0002]
[Prior art]
The compressive strength Fc of concrete can be measured by collecting a cylindrical concrete core from a concrete building, pressurizing it with a compression tester, and measuring the applied pressure when the concrete core is crushed. However, the size of the core used for pressurization in the compression tester is very large with a diameter of about 10 cm and a length of about 20 cm, and it takes a lot of labor to collect the core itself. There is also a problem that the number of points that can be collected is limited. For this reason, the compressive strength Fc of concrete is generally measured (estimated) indirectly by a nondestructive test method instead of direct measurement using a compression tester. .
[0003]
As an indirect measurement (estimation) method of the compressive strength Fc of concrete, the rebound degree Rs of the concrete surface is measured by a concrete test hammer, and a predetermined arithmetic expression (for example, the Japan Society of Materials Science concrete strength is carried out from this repulsion degree Rs. A method for estimating and calculating the compression strength Fc using the “commitment strength estimation formula (1958) by Schmitt hammer: Fc = 13Rs−184”) of the judgment committee is widely used. A strength estimation method by pulling out a nail or a bolt is also known.
[0004]
In addition, as a technique related to the above, JP-A-11-51933 discloses measurement data on the properties of concrete (for example, rebound hardness or compressive strength with respect to the depth from the surface of the concrete structure, drying shrinkage with respect to the age of the concrete) (Strain, neutralization depth)
Y = (A1-A2) / [1 + exp [(X-X0)] / dx]] + A2
The technique of specifying the property or final value of concrete by performing regression analysis using is disclosed.
[0005]
JP-A-10-19881 discloses a first estimation method for estimating compressive strength Fc from the rebound hardness of concrete and the water absorption weight before drying of the hardened concrete specimen to be measured. Then, the specimen is dried at a constant temperature at a predetermined temperature, the dry weight after drying is measured, and the water absorption rate Q obtained from the ratio of the water absorption amount obtained by subtracting the dry weight from the water absorption weight and the water absorption weight before drying is obtained. Each of the second estimation methods for estimating and calculating the compressive strength of concrete is described by substituting into a predetermined arithmetic expression.
[0006]
[Problems to be solved by the invention]
However, the various techniques described above have drawbacks as described below. That is, the method of estimating the compressive strength Fc from the rebound degree Rs of the concrete surface measured using a concrete test hammer has a problem that the estimation accuracy of the compressive strength Fc is low. That is, the rebound degree Rs of the concrete surface is affected by the neutralization and wet state (moisture content) of the concrete surface, and when the concrete surface is neutralized over time, the hardness of the concrete surface increases. The estimation result of the compression strength Fc tends to be higher than the actual compression strength Fc. Moreover, when the moisture content of the concrete is high, the hardness of the concrete surface decreases, and the estimation result of the compressive strength Fc tends to be lower than the actual compressive strength Fc.
[0007]
Further, in estimating the compressive strength Fc of long-term concrete, it is widely performed to further correct the estimated value of the compressive strength Fc obtained from the rebound degree Rs using a correction coefficient called the age coefficient α. Yes. However, the age coefficient α currently used in Japan is stipulated in DIN 4240 (1962 version) for spring impact hammers (the spring impact hammers are different from concrete test hammers). This is a value, and the basis for applying this value is sparse, and the compression strength Fc after correction by the age coefficient α is often very different from the actual compression strength Fc.
[0008]
The inventors of the present application manufactured a plurality of types of concrete each having a different water / cement ratio (water / cement ratio = 40%, 55%, 70%), and put a concrete test hammer on each concrete. In addition to measuring the resilience Rs of the concrete surface, the core specimen was pressed with a compression tester to measure the compressive strength Fc. FIG. 9 is a plot of the above experimental results, and two typical arithmetic expressions for calculating the compressive strength Fc from the resilience Rs (the above-mentioned arithmetic expression of the Japan Society of Materials: Fc = 13Rs−184, Oba / Akita et al.'S calculation formula at Tokyo Building Materials Laboratory: Fc = 10Rs-110) It is. In addition, as a material age coefficient (alpha), the value ((alpha) = 0.63) applied to the concrete which passed for about 8 years or more by reference is used.
[0009]
As is clear from the experimental results shown in FIG. 9, the relationship between the resilience Rs and the compressive strength Fc varies greatly depending on the water / cement ratio of the concrete (indicated as W / C in the figure), and the regression is applied to all data. The correlation coefficient r between the regression equation and the data at the time of analysis is very low, r = 0.36. 9 may not take into account the water / cement ratio of concrete, and the correlation with the experimental results dispersed in FIG. 9 is very low. It can be understood that the estimation accuracy of the compressive strength Fc is very low. It is also clear that the estimation result of the compressive strength Fc particularly when the correction is made by the age coefficient α tends to show a considerably lower value than the actual compressive strength Fc.
[0010]
On the other hand, with respect to the method of estimating the compressive strength Fc of concrete by pulling out a nail or bolt, when a part of concrete is pulled out in a cone shape and destroyed, the aggregate existing near the test position is pulled out to the breaking load. Because of this, the estimation accuracy of the compressive strength Fc is insufficient. For example, according to “Reinforced Concrete Course 4th Edition” (by Shizuo Saka, Sangyo Tosho, 1952 p.56), the compressive strength Fc is 50 [kgf / cm²] (4.903325 [MPa]) ~ 300 [kgf / cm²] (29.41995 [MPa]), it has been reported that only an estimated accuracy of about ± 15% is obtained.
[0011]
Japanese Patent Laid-Open No. 11-51933 discloses that the rebound hardness of a concrete core sampled by boring is measured at a plurality of locations having different depths from the surface, and the surface weakening depth is estimated by regression analysis. Although it is described that the change in the adiabatic temperature rise is measured in a time series over a period of time and the age of the ultimate adiabatic temperature rise is estimated, and the age at which the ultimate adiabatic temperature rise is estimated, the compression of the concrete Regarding the estimation of the strength Fc, it is only described that “the rebound hardness measured with a Schmitt hammer can be converted into the compressive strength of concrete”. Even if the technique described in the above publication is used, the compressive strength Fc is increased. It is difficult to estimate with accuracy.
[0012]
Furthermore, among the estimation methods of the compressive strength Fc described in Japanese Patent Laid-Open No. 10-19881, the first estimation method is a well-known estimation method and arithmetic expression for estimating the compressive strength Fc from the rebound degree Rs of concrete. However, there is a problem that the estimation accuracy of the compression strength is low. In the second estimation method, it is necessary to dry the concrete specimen in a predetermined temperature range (for example, 100 to 105 ° C.) with a constant temperature dryer, and it is also necessary to measure the weight before and after drying with a measuring device. There is a problem that the measurement takes time and labor.
[0013]
The present invention has been made in consideration of the above facts, and it is an object of the present invention to obtain a concrete strength estimation method and a concrete strength estimation device capable of estimating the compressive strength of concrete with high accuracy by a nondestructive test method. is there.
[0014]
[Means for Solving the Problems]
In the method of estimating the compressive strength Fc of concrete from the rebound degree Rs of the concrete surface measured using a concrete test hammer, the inventors of the present application mainly cause the high estimation accuracy as described above. We thought that the surface of the concrete was neutralized, and we predicted that the degree of repulsion inside the non-neutralized concrete was highly correlated with the compressive strength Fc of the concrete. And in estimating the internal rebound, we expect that the indentation hardness of concrete may be used, and the Vickers hardness of concrete, which is a kind of indentation hardness, and the rebound of concrete In order to investigate the relationship, an experiment described below was conducted.
[0015]
That is, concrete with water / cement ratio = 40%, 55%, 70% is placed in the form of blocks and placed in an outdoor exposure environment. Separately from these concrete blocks, water / cement ratio = 55% Is placed in a block shape and placed in a neutralization-promoting environment (carbon dioxide concentration 5%, temperature 20 ° C, humidity 60% RH), and at a specified age (the number of days since placement) At that time, the compressive strength Fc of concrete and the resilience Rs on the concrete surface are measured, the neutralization depth C of the concrete, the Vickers hardness Hs at a depth of 1 mm from the concrete surface, the concrete surface The Vickers hardness Hi at a position 20 mm deep was measured.
[0016]
The compressive strength Fc of concrete is measured by collecting a cylindrical concrete core having a diameter of 10 cm and a length of 20 cm, and pressing the collected core with a compression tester.・ Measured using a test hammer. On the other hand, the neutralization depth C of concrete and the Vickers hardness Hs of concrete were measured as follows.
[0017]
In other words, a small cylindrical concrete core with a diameter of 32 mm and a length of 30 mm was sampled, and the sampled core was cut parallel to the axis of the cylinder with a concrete cutter to cut out a substantially flat test piece with a thickness of 10 mm. How much neutralization has progressed from the concrete surface, such as by applying a phenolphthalein solution to the separated concrete piece and confirming the area where discoloration has occurred (the part that has been neutralized does not discolor) The neutralization depth C representing whether or not was measured. In addition, the measurement surface (cut surface) of the approximately 10mm-thick test piece that was cut out was polished to a mirror finish, and the Vickers hardness Hs and depth 1mm deep from one side of the test piece corresponding to the concrete surface. A Vickers hardness Hi of 20 mm was measured.
[0018]
The Vickers hardness Hs, Hi is a diamond square pyramid indenter with a face angle of 136 °, a test load of 25 [g] is maintained for 20 seconds, and the test load F [N] when the test surface is indented and a permanent indentation. Surface area S [mm] obtained from the diagonal length of the sample (mean value d [mm])²] Was calculated (measured) based on the following formula.
Hs (Hi) = 0.102 F / S = 0.1891 F / d²
Also, the number of measurements is 20 points, the average value of the measured values of Vickers hardness Hs (Hi) is calculated, the measured values exceeding the range of ± 20% of the average value are discarded, and the number of measured values is always a predetermined number The measured value was replenished so that the standard was 20 points, and the re-averaged value was taken as Vickers hardness Hs (Hi).
[0019]
In this experiment, the age at the time of measurement was set so that the 1 mm depth part from the concrete surface was neutralized and the 20 mm depth part from the concrete surface was not neutralized. By selecting and measuring the neutralization depth C, it was confirmed that the neutralization depth C was 1 mm <C <20 mm.
[0020]
The inventors of the present application, among the measurement results obtained from the above experiments, firstly, the rebound degree Rs on the concrete surface and the Vickers hardness Hs at a position 1 mm deep from the concrete surface, that is, the neutralized portion of the concrete. Was obtained by regression analysis (see FIG. 1). as a result,
Hs = 1.82Rs-36.2 (1)
The following regression equation was obtained, and the correlation coefficient r was a very high value of r = 0.84. Therefore, as is apparent from FIG. 1, the rebound degree Rs on the concrete surface was found to have a strong correlation with the Vickers hardness Hs of the neutralized portion of the concrete.
[0021]
Subsequently, the inventors of the present invention have a strong correlation with the internal non-neutralized Vickers hardness Hi in the same manner as described above for the repulsion degree Ri inside the concrete that is not neutralized. Similar to the equation (1), it is assumed that there is a relationship as the following equation (2).
Hi = a · Ri + b (2)
However, Ri is a hypothetical resilience degree when it is assumed that the resilience degree can be measured inside the non-neutralized concrete, and a and b are constants, and a = 1.82, b = − as in the equation (1). 36.2. If the above equation (2) holds, if the relationship between the Vickers hardness Hs of the neutralized portion of the concrete and the Vickers hardness Hi of the non-neutralized portion is known, the rebound degree Rs on the concrete surface The repulsion degree inside the concrete (unneutralized portion) can be derived using the equations (1) and (2).
[0022]
For this reason, the inventors of the present application, as a parameter representing the relationship between the Vickers hardness Hs of the neutralized part of concrete and the Vickers hardness Hi of the non-neutralized part, is the ratio β (= Hi / Hs: The surface hardness correction coefficient β is obtained from the above experimental results, and the relationship with the neutralization depth C estimated to be correlated with the surface hardness correction coefficient β is obtained. (See FIG. 2). As a result, as is apparent from FIG. 2, the surface hardness correction coefficient β was found to have a certain degree of correlation with the neutralization depth C.
[0023]
Moreover, the following (3) Formula is obtained by dividing (2) Formula by (1) Formula,
[0024]
[Expression 1]

[0025]
By transforming the above expression (3), an arithmetic expression (the following expression (4)) regarding the rebound degree Ri in the non-neutralized portion of the concrete is obtained.
Ri = β · Rs− (1−β) · b / a (4)
[0026]
Based on the relationship between the neutralization depth C and the surface hardness correction coefficient β shown in FIG. 2, the inventors of the present application have a neutralization depth C of C ≦ 1 [mm] as shown by a broken line in FIG. In this case, β = 1 as the surface hardness correction coefficient β, and β = 0.5 / C + 0.5 as the surface hardness correction coefficient β when the neutralization depth C is 1 [mm] <C ≦ 5 [mm] When the neutralization depth C is C> 5 [mm], β = 0.6 is used as the surface hardness correction coefficient β, and the measurement result of the resilience Rs on the concrete surface indicates that the concrete according to the above equation (4) The repulsion degree Ri in the non-neutralized portion of was determined. Then, the relationship between the rebound degree Ri and the compressive strength Fc of the concrete was obtained by regression analysis (see FIG. 3B). as a result,
Fc [kgf / cm²] = 15.9 Ri-246 (5)
The following regression equation was obtained, and the correlation coefficient r was an extremely high value of r = 0.96.
[0027]
FIG. 3 (A) shows the relationship (correlation coefficient r = 0.61) between the rebound degree Rs on the concrete surface (neutralized portion) and the compressive strength Fc of the concrete. FIG. 3 (B) is shown in FIG. As is clear from comparison with A), the rebound degree Ri in the non-neutralized portion of the concrete (the modified repulsion degree Ri in FIG. 3B) has been conventionally used for estimating the compressive strength Fc of the concrete. Compared with the rebound degree Rs on the concrete surface, the correlation with the compressive strength Fc of the concrete is very high, and it is clear that the compressive strength Fc of the concrete can be estimated with high estimation accuracy.
[0028]
Subsequently, the inventors of the present application corrected the resilience degree Rs on the concrete surface to a modified resilience degree Ri corresponding to the resilience degree inside the concrete (unneutralized portion) using the surface hardness correction coefficient β. In order to confirm the effectiveness of the method for estimating the compressive strength Fc of concrete from the modified resilience Ri, calculation of the modified resilience Ri using the experimental data of experiments conducted in the past, and the modified resilience Ri and compression Work to confirm the correlation of intensity Fc was performed.
[0029]
In the past experiments, three types of treatment conditions were prepared as non-treatment (dry state), water spray, and 24-hour water supply as water treatment conditions for the concrete surface when measuring the resilience Rs on the concrete surface. / Concrete ratio = 40%, 55%, 70% of each concrete block is manufactured and placed in an outdoor exposure environment. When the specified age is reached, each concrete with the same water / cement ratio For each of the blocks, the water repellent treatment conditions for the concrete surface were made different from each other, and the rebound degree Rs was measured. Each of C was measured.
[0030]
FIG. 4 (A) shows the relationship between the rebound degree Rs on the concrete surface obtained by past experiments and the compressive strength Fc of the concrete, and FIG. 4 (B) corresponds to the neutralization depth C. The relationship between the modified resilience Ri calculated from the resilience Rs according to the above equation (4) and the compressive strength Fc of concrete using the surface hardness correction coefficient β is shown. As is clear from comparison of FIG. 4B with FIG. 4A, the correlation coefficient r with the compressive strength Fc of concrete is 0.36 →→ It was confirmed that it improved significantly to 0.76.
[0031]
The inventors of the present application determined the rebound degree Rs on the concrete surface based on the result of the above-described experiment and the confirmation work using the past experimental data, the hardness (indentation) of the concrete surface part (neutralized part). After correcting based on the relationship between the hardness (hardness) and the hardness (indentation hardness) inside the concrete (the part that has not been neutralized), the compressive strength Fc of the concrete is estimated based on the rebound degree Ri after the correction. For example, the knowledge that the compressive strength Fc of concrete can be estimated with high accuracy was obtained.
[0032]
Based on the above, the concrete strength estimating method according to the first aspect of the present invention measures the rebound degree Rs of the surface portion of the concrete whose compression strength is to be estimated using a concrete test hammer, and the surface portion is neutralized. The rebound degree Rs of the surface portion of the concrete to be estimated is corrected based on the relationship between the hardness of the surface portion (the neutralized portion) and the internal hardness of the non-neutralized concrete, and after the correction Since the compressive strength of the concrete to be estimated is estimated based on the rebound degree Ri, even if the surface portion of the concrete to be estimated is neutralized, as is clear from the above-described experimental results, it is affected by that. In addition, the compressive strength of the concrete to be estimated can be estimated with high accuracy.
[0033]
In the invention according to claim 1, the compressive strength of the estimation target concrete can be estimated from the rebound degree Rs of the surface portion of the estimation target concrete measured using a concrete test hammer. There is no need to extract concrete from the building as in the case where Fc is directly measured by a compression tester, and the compressive strength of the concrete can be estimated by a nondestructive test method.
[0034]
In the first aspect of the invention, the relationship between the hardness of the surface portion and the internal hardness of the concrete having a neutralized surface portion is, for example, as described in claim 2, the surface portion is neutralized. It is possible to use a surface hardness correction coefficient β corresponding to the ratio of the hardness of the surface portion and the internal hardness of the concrete that is being used. Further, in place of the surface hardness correction coefficient β, it is also possible to use an arbitrary parameter whose value changes according to the hardness of the surface portion and the internal hardness of the concrete.
[0035]
By the way, the surface hardness correction coefficient β described in claim 2 has a correlation with the neutralization depth of the concrete as is clear from FIG. 2 described above, and the value depends on the neutralization depth of the concrete. Change. Therefore, when the surface hardness correction coefficient β is used as the relationship between the hardness of the surface portion and the internal hardness as in the invention described in claim 2, as described in claim 3, the surface hardness correction coefficient β Is related to the neutralization depth in the concrete whose surface is neutralized, the neutralization depth of the concrete to be estimated is measured, and the surface corresponding to the neutralization depth of the concrete to be estimated is measured. It is preferable to correct the resilience Rs of the surface portion of the estimation target concrete using the hardness correction coefficient β.
[0036]
Thereby, even when the neutralization depth of the concrete whose compression strength is to be estimated varies, the surface hardness correction coefficient β is a value corresponding to the neutralization depth of the estimation target concrete, that is, the estimation object. A value that accurately represents the ratio of the hardness of the surface portion of the concrete to the hardness of the inside is used, and the rebound degree Rs of the surface portion is corrected using the surface hardness correction coefficient β, and the compressive strength of the concrete is estimated. As a result, it is possible to further improve the estimation accuracy of the compressive strength of the concrete.
[0037]
In order to measure the neutralization depth of the estimation target concrete, it is necessary to scrape the estimation target concrete to a depth that reaches a portion that has not been neutralized. However, the neutralization of concrete is caused by the reaction of carbon dioxide in the air with the concrete in the exposed environment where the concrete is placed, and the neutralized part gradually progresses from the surface of the concrete to the inside. However, according to the existing neutralization rate formula (Kishiya method, etc.), the neutralization depth of concrete is 30mm to 40mm even if the elapsed time is 100 years under the outdoor exposure environment of concrete with a water / cement ratio of 60%. It is. When the water / cement ratio is less than 60% or when the age is small, the neutralization depth of concrete is smaller.
[0038]
For this reason, in order to estimate the compressive strength Fc of the concrete in the building, even when measuring the neutralization depth of the concrete in the building, the concrete core is used to directly measure the compressive strength Fc by a compression tester. The amount of concrete that must be scraped from the building to reach the non-neutralized part is very small compared with the case of collecting the sample, for measuring the neutralization depth (estimating the compressive strength Fc) There is little effect on the building by scraping the concrete.
[0039]
Further, the relationship between the surface hardness correction coefficient β and the neutralization depth of the concrete described in claim 3 is, for example, as described in claim 4, the neutralization depth C of the estimation target concrete is C ≦ When 1 [mm], β = 1 is used as the surface hardness correction coefficient β, and when the neutralization depth C is 1 [mm] <C ≦ 5 [mm], the surface hardness correction coefficient β is β = When 0.5 / C + 0.5 is used and the neutralization depth C is C> 5 [mm], β = 0.6 can be used as the surface hardness correction coefficient β. The relationship between the neutralization depth C and the surface hardness correction coefficient β described in claim 4 is a relationship derived from the experimental results by the inventors of the present application, and further improves the estimation accuracy of the compression strength of the estimation target concrete. be able to.
[0040]
Further, when the surface hardness correction coefficient β is used as the relationship between the hardness of the surface portion and the internal hardness as in the invention described in claim 2, for example, as described in claim 5, Using the surface hardness correction coefficient β, the modified resilience Ri corresponding to the resilience is
Ri = β · Rs− (1−β) · b / a
The repulsion degree Rs of the surface portion of the concrete to be estimated can be corrected by calculating with the following equation (where a and b are constants). As constants a and b in the above arithmetic expression, for example, a = 1.82 and b = −36.2 can be used as described in claim 6.
[0041]
The values of the arithmetic expression according to claim 5 and the constants a and b according to claim 6 are both derived from the experimental results by the inventors of the present application. By using the value, the compressive strength of the concrete to be estimated can be estimated with high estimation accuracy, similarly to the experimental results described above.
[0042]
By the way, as is clear from the result shown in FIG. 4B, the deviation from the straight line representing the regression equation of formula (5) is large particularly for the concrete data with water / cement ratio = 70%. There is also a lot of data, and it can be understood that the estimation accuracy of the compression strength Fc from the corrected rebound degree Ri is relatively low. The inventors of the present application consider that the above phenomenon is affected by the water treatment conditions on the concrete surface, and the results shown in FIG. 4B are obtained for each water treatment condition (no treatment, water spray, 24 hours water supply). The relationship between the modified resilience Ri and the compressive strength Fc was determined by regression analysis for each water treatment condition. The results are shown in FIG.
[0043]
The moisture content of the concrete surface for each moisture treatment condition is (no treatment <water spray <24 hours water supply), and it is clear from comparison between (A) to (C) in FIG. As the moisture content of the concrete surface when measuring the surface resilience increases, the correlation between the modified resilience Ri and the compressive strength Fc increases (the value of the correlation coefficient r is high), especially water / cement. It can be understood that the deviation from the straight line representing the regression equation decreases as the concrete surface data with a ratio = 70% increases in water content on the concrete surface.
[0044]
For this reason, in the invention described in claim 1, for example, as described in claim 7, when measuring the resilience of the surface portion of the concrete whose compression strength is to be estimated using a concrete test hammer, It is preferable that the surface of the concrete to be estimated is wet. Thereby, as is clear from the experimental results described above, it is possible to further improve the estimation accuracy of the compressive strength of the concrete.
[0045]
Moreover, the difference in the measurement conditions in the experimental data shown in FIGS. 5 (A) to 5 (C) is only the moisture treatment conditions when measuring the rebound degree Rs of the surface portion of the concrete using a concrete test hammer. Considering that the correction from the rebound degree Rs of the surface portion to the corrected rebound degree Ri is linear conversion, the rebound degree Rs is compressed from the rebound degree Rs to the compressive strength Fc without correcting the rebound degree Rs of the concrete surface part to the corrected repulsion degree Ri. Even when directly estimating the rebound degree Rs of the concrete surface portion, if the concrete surface portion is kept in a wet state, it can be easily estimated that the estimation accuracy of the compressive strength Fc is improved.
[0047]
  Claims7In the described invention, when the surface portion of the concrete is wetted, for example, the claim8As described in, it can be performed by spraying water on the surface portion of the concrete to be estimated or by supplying water for a predetermined time or more. Further, from the experimental results shown in FIGS. 5A to 5C, it is clear that the estimation accuracy of the compressive strength of the concrete is improved by increasing the water content of the concrete surface when measuring the resilience of the concrete surface. Therefore, when the surface of the concrete is wet, water is supplied to the surface of the concrete, preferably 10 minutes or more, more preferably 1 hour or more, so that the water content of the concrete surface is as high as possible. It is preferable to do.
[0048]
  Claim9The concrete strength estimation apparatus according to the invention described above is characterized in that the rebound degree of the surface portion of the concrete to be estimated for compressive strength measured using a concrete test hammer is the surface of the concrete in which the surface portion is neutralized. Correction means for correcting based on the relationship between the hardness of the part and the internal hardness that has not been neutralized, and an estimation means for estimating the compressive strength of the estimation target concrete based on the degree of rebound after correction by the correction means; Therefore, the compressive strength of the concrete can be estimated with high accuracy by the non-destructive testing method as in the first aspect of the invention.
[0049]
  Claims9In the described invention, for example, claim 10As described in the above, as the relationship between the hardness of the surface portion and the internal hardness, the surface hardness correction coefficient β corresponding to the ratio of the hardness of the surface portion and the internal hardness in the concrete where the surface portion is neutralized, A storage means for storing in relation to the neutralization depth in the concrete having a neutralized surface portion, and a measurement means capable of measuring the neutralization depth of the concrete to be estimated are further provided, and the correction means includes the measurement It is preferable that the degree of resilience of the surface portion of the estimation target concrete is corrected using the surface hardness correction coefficient β corresponding to the neutralization depth of the estimation target concrete measured by the means. Thereby, similarly to the invention according to claim 3, it is possible to further improve the estimation accuracy of the compressive strength of the concrete to be estimated.
[0050]
  In addition, the neutralization depth of concrete can be measured by, for example, collecting a concrete core from concrete, applying a reagent to the side of the collected concrete core, and confirming the area where discoloration has occurred. However, there is a problem that the work is very complicated. For this reason, claim 10The measuring means according to the described invention is, for example, claim 1.1As described above, a perforation means capable of perforating concrete, a supply means for supplying a reagent to concrete powder generated by the perforation means by the perforation means, and a reagent supplied by the supply means And detecting means for detecting whether or not a color change has occurred in the concrete powder.
[0051]
  Claim 11In the described invention, a reagent (for example, a phenolphthalein solution or the like) is supplied to the concrete powder generated as a result of drilling holes in the concrete to detect whether or not color change has occurred in the concrete powder. When the detection result changes, it can be determined that the depth of the hole drilled by the drilling means has reached the boundary between the neutralized part and the non-neutralized part of the concrete. The neutralization depth can be measured by measuring the depth of the holes.
[0052]
Accordingly, it is not necessary to collect a concrete core from concrete or to apply a reagent to the side surface of the collected concrete core, so that the neutralization depth can be easily measured. Further, if a detection means for detecting the depth of the hole when the detection result by the detection means changes is further provided, the operation for measuring the neutralization depth can be further simplified.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 6 shows an intensity estimation apparatus 10 according to this embodiment. The strength estimation device 10 corresponds to the concrete strength estimation device according to the present invention.
[0054]
  The intensity estimation apparatus 10 includes an apparatus main body 12. The apparatus main body 12 includes a microcomputer in which a CPU, a ROM, a RAM, and an input / output port are connected to each other via a bus, and can display arbitrary information. A display 12A is included. The device body 12 is claimed.9The ROM is provided with the functions as the correcting means and the estimating means described in claim 1.0This corresponds to the storage means described in (1). In the apparatus main body 12, a concrete test hammer 14 for measuring the repulsion degree Rs of the concrete surface and a neutralization depth measuring machine 16 for measuring the neutralization depth C of the concrete are connected to the communication line. Are connected to each other. The neutralization depth measuring machine 16 is claimed in claim 1.0It corresponds to the measuring means described in.
[0055]
As the concrete test hammer 14, an arbitrary configuration can be adopted from various known configurations. For example, although illustration is omitted, there is a plunger 18 whose tip is brought into contact with a concrete measurement surface during measurement. The main body 14A is provided with a hammer for striking the plunger 18 and a holding mechanism for holding the hammer in a predetermined position. The tip of the plunger 18 is made of concrete. When the main body 14A is pressed toward the concrete side while being in contact with the measurement surface, and the plunger 18 is pushed into the main body 14A by a predetermined amount, the holding of the hammer by the holding mechanism is released and the hammer pushes the plunger 18. The amount of rebound of the plunger 18 that rebounds according to the rebound degree Rs of the concrete surface is measured. By, it is possible to adopt a configuration for measuring the rebound of Rs of concrete surface.
[0056]
The concrete test hammer 14 according to the present embodiment includes a sensor for measuring the amount of rebound of the plunger 18, and the amount of rebound measured by the sensor is converted into a rebound degree Rs of the concrete surface according to a predetermined arithmetic expression. The signal processing circuit which transmits the measured value of the repulsion degree Rs to the apparatus main body 12 via is incorporated.
[0057]
On the other hand, as shown in FIG. 7, the neutralization depth measuring machine 16 includes a frame 20 built in the main body 16A and a bottomed cylindrical rotating body 22 having a bottom having a thickness of a predetermined value or more as a pair of bearings. 24 is supported rotatably. A magnet 26 is attached to a position corresponding to the gap between the pair of bearings 24 in the outer peripheral portion of the rotating body 22, and the exciting coil is disposed on the frame 20 at a position corresponding to the magnet 26 with a gap from the magnet 26. 28 is attached. Therefore, the rotating body 22 is rotated by energizing the exciting coil 28.
[0058]
A small-diameter circular hole 30 is formed on one end side (the side opposite to the side where the opening 22A is formed) along the axis of the rotating body 22, and a cartridge 32 is screwed into the inner wall of the circular hole 30. An internal thread (reverse thread) is formed. The cartridge 32 is hollow and has a substantially cylindrical shape as a whole. A hole is formed at one end along the axis, and a cylindrical rib 32A is provided around the hole so as to be coaxial with the cartridge 32 body. Yes. A male screw (reverse screw) is formed on the outer periphery of the rib 32A. Accordingly, the cartridge 32 is rotated integrally with the rotating body 22 in a state where the cartridge 32 (the rib 32A thereof) is screwed into the rotating body 22 (the circular hole 30 thereof).
[0059]
A storage part for storing a reagent such as a phenolphthalein solution is formed inside the cartridge 32, and pressure can be applied to the reagent stored in the storage part by sending air into the storage part. A pressurizing mechanism is provided (not shown). An O-ring 34 is attached to the bottom of the circular hole 30 of the rotating body 22, and the rib 32 </ b> A of the cartridge 32 is brought into close contact with the bottom of the circular hole 30 through the O-ring 34 in a state where the cartridge 32 is screwed. The
[0060]
In addition, a passage 36 through which the reagent passes is formed in the rotating body 22 along the axis. One end of the passage 36 is opened at the center of the bottom of the circular hole 30, and the other end is the center of the bottom of the opening 22A. Is open. A valve 38 is provided in the middle of the passage 36. The valve 38 is connected to a link mechanism (not shown), and is opened and closed in conjunction with the rotation of the rotating body 22. Specifically, when the rotation of the rotating body 22 is stopped, the valve 38 is closed and the rotating body 22 is When rotating, the valve 38 is opened.
[0061]
On the other end side (the side where the opening 22A is formed) along the axis of the rotating body 22, a plurality of chucks 42 for gripping the drill bit 40 are disposed inside the opening 22A. The chuck 42 is supported by the rotating body 22 via a gear mechanism (not shown) that can change the interval between the chucks 42. The plurality of chucks 42 are rotated by a tool (not shown) of the gear mechanism so that the distance between the chucks 42 is reduced with the base of the drill bit 40 inserted into the opening 22A. It is positioned and held at a position coaxial with the rotating body 22. Thereby, the drill bit 40 is rotated integrally with the rotating body 22.
[0062]
The drill bit 40 used in the neutralization depth measuring machine 16 is made of a metal material having sufficient strength for drilling into concrete, and a spiral groove 44 is formed on the outer periphery. The drill bit 40 is used to make a hole in the concrete to be measured when measuring the neutralization depth C of the concrete to be measured. In addition, the drill bit 40 is formed with a hole 46 penetrating the drill bit 40 along the axis of the drill bit 40, and the hole 46 is branched into a plurality of portions at the tip of the drill bit 40, each near the tip of the drill bit 40. It penetrates in different positions.
[0063]
On the other hand, an O-ring 48 is attached to the bottom of the opening 22A, and the base side of the drill bit 40 is inserted into the opening 22A until the bottom surface of the drill bit 40 abuts against the bottom surface of the opening 22A. With the bit 40 gripped, the bottom surface of the drill bit 40 is brought into close contact with the bottom of the opening 22 </ b> A via the O-ring 48.
[0064]
Thereby, when the cartridge 32 in which the reagent is stored in the storage part is screwed into the circular hole 30 and the storage part is pressurized by the pressurizing mechanism, the reagent in the storage part is ejected from the cartridge 32 and into the passage 36. When the valve 38 is opened by reaching the position where the valve 38 is arranged and the rotating body 22 is rotated, the valve 38 is opened from the passage 36 into the hole 46 of the drill bit 40 and passes through the hole 46. It will be ejected from a plurality of locations near the tip of the bit 40.
[0065]
Further, the main body 16A of the neutralization depth measuring device 16 has a perforation depth scale 50 and a color change detection unit 52 so as to protrude in the same direction as the drill bit 40 attached to the main body 16A (rotating body 22). Is attached.
[0066]
The drilling depth scale 50 is slidable in the direction of arrow A in FIG. 7 (the direction in which it is housed in the main body 16A) and in the opposite direction (the direction in which it protrudes from the main body 16A). When measuring the chemical depth C, it is slid to the measurement start position (position shown in FIG. 7) where the protrusion amount from the main body 16A is the same as that of the drill bit 40. Further, while the drill bit 40 is drilling a hole in the concrete to be measured, the tip of the drilling depth scale 50 is pressed by the surface of the concrete to be measured as the depth of the drilled hole increases. Then, the drilling depth scale 50 is slid in the direction of arrow A in FIG. A sensor for detecting the slide amount of the drilling depth scale 50 from the measurement start position is provided in the main body 16A.
[0067]
The color change detection unit 52 has a substantially L-shaped outer shape, and is attached so that the tip part faces the drill bit 40. The light-emitting element that emits light toward the drill bit 40 is attached to the tip part, A light receiving element that receives light emitted from the light emitting element and reflected by the drill bit 40 is incorporated, and the light receiving element is connected to a signal processing circuit (none of which is shown).
[0068]
When measuring the neutralization depth C, holes are drilled in the concrete to be measured by the drill bit 40. At this time, the reagent is ejected from a plurality of locations near the tip of the drill bit 40. The concrete powder generated by the drilling is attached to the groove 44 of the drill bit 40 in a state of being mixed with the reagent and discharged from the hole. Therefore, the concrete powder that adheres to the groove 44 and is discharged does not change its color if it is neutralized, and changes to a red color by reacting with the reagent if it is not neutralized. For this reason, the signal processing circuit connected to the light receiving element determines whether the concrete powder adhering to and discharged from the groove 44 has changed to a red color based on the signal input from the light receiving element. A signal is output when it is determined that there has been a change.
[0069]
The signal processing circuit of the color change detection unit 52 is connected to a control circuit (not shown). When the measurement of the neutralization depth C is instructed by turning on a switch (not shown), the excitation coil 28 is energized. As a result, the rotating body 22 (and the drill bit 40) is rotated (with this rotation, the valve 38 is opened and the reagent is ejected from the vicinity of the tip of the drill bit 40), and the concrete powder that adheres to the groove 44 and is discharged. When a signal indicating that the color changes to red is input from the signal processing circuit, the energization to the exciting coil 28 is stopped and the rotation of the rotating body 22 (and the drill bit 40) is stopped.
[0070]
Further, a sensor for detecting the slide amount of the drilling depth scale 50 is connected to the control circuit, and the drilling depth scale is based on the sensor output when the rotation of the rotating body 22 (and the drill bit 40) is stopped. A measured value of 50 slide amount (depth of the hole drilled by the drill bit 40), that is, the neutralization depth C is transmitted to the apparatus main body 12 via the communication line.
[0071]
  Of the neutralization depth measuring machine 16 described above, the drill bit 40 is claimed in claim 1.1The hole 32 of the cartridge 32 (pressure mechanism), the passage 36, the valve 38, and the drill bit 40 is provided in the punching means described in claim 1.1The color change detection unit 52 is provided in the supply means described in claim 1.1The perforation depth scale 50 and a sensor that detects the slide amount of the perforation depth scale 50 detect the depth of the hole when the detection result of the detection means changes. It functions as a detection means.
[0072]
On the other hand, the surface hardness correction coefficient β is stored in advance in the ROM of the apparatus main body 12 in association with the neutralization depth C. Specifically, the following equation (6) is stored.
[0073]

Further, the ROM of the apparatus main body 12 stores in advance an arithmetic expression (the following (7)) for estimating and calculating the corrected repulsion degree Ri from the rebound degree Rs of the concrete surface.
Ri = β · Rs− (1-β) · −36.2 / 1.82 (7)
[0074]
Further, the ROM of the apparatus main body 12 stores in advance an arithmetic expression (the following (8)) for estimating and calculating the compressive strength Fc of concrete from the corrected resilience Ri.
Fc = d · Ri-e (8)
It should be noted that the values of the constants d and e in the equation (8) may be values that can accurately calculate the compression strength Fc from the modified resilience Ri. As will be described later, in the present embodiment, in order to improve the estimation accuracy of the compressive strength Fc, the surface of the concrete to be measured for the resilience Rs is supplied in advance, and the water content of the concrete surface is increased before the resilience Rs is increased. As is apparent from the regression equations shown in FIGS. 5A to 5C, the values of the constants d and e in the regression equation that minimizes the correlation coefficient r are the conditions for supplying water to the concrete surface. It differs depending on (moisture treatment conditions). For this reason, as the values of the constants d and e in the equation (8), values corresponding to the water supply conditions (moisture treatment conditions) performed when measuring the repulsion degree Rs may be used.
[0075]
Next, as an operation of the present embodiment, with reference to FIG. 8, the operator's work when investigating the compressive strength Fc of the concrete of the building using the strength estimation device 10 and the processing performed by the strength estimation device 10 will be described. explain.
[0076]
When investigating the compressive strength Fc of concrete in a building, an operator should first measure the portion of the target building where the compressive strength Fc is to be investigated (surface resilience Rs and neutralization depth C). (Step 70), and the water content on the surface of the concrete at the measurement location is increased by supplying water to the selected measurement location (Step 70). Note that this water supply may be simply sprayed with water, but since the purpose is to improve the accuracy of estimation of the compressive strength Fc, it is desirable to supply water for 10 minutes or more, and more desirably for 1 hour or more. It is preferable to greatly increase the amount of water to a predetermined value or more.
[0077]
When the water supply to the measurement location is completed, the operator activates the strength estimation device 10 by turning on the power of the strength estimation device 10 (step 74). Thereby, the strength estimation process is executed in the apparatus main body 12 of the strength estimation apparatus 10, and in step 80, the degree of restitution Rs is displayed by displaying on the display 12A a message requesting the measurement of the rebound degree Rs of the concrete surface at the measurement location. Ask the operator to measure In the next step 82, it is determined whether or not the measurement data of the rebound degree Rs is input from the concrete test hammer 14, and step 82 is repeated until the determination is affirmed.
[0078]
After confirming the message displayed on the display 12A, the operator performs an operation of measuring the rebound degree Rs of the concrete surface at the measurement location using the concrete test hammer 14 (step 76). That is, in a state where the hammer of the concrete test hammer 14 is held at a predetermined position by the holding mechanism, the concrete test hammer 14 is held so that the tip of the plunger 18 abuts against the concrete surface of the measurement location, Further, the main body 14A is pressed toward the concrete side so that the plunger 18 is pushed into the main body 14A by a predetermined amount.
[0079]
As a result, the hammer is released by the holding mechanism and the hammer strikes the concrete surface via the plunger 18, and the amount of rebound of the plunger 18 that rebounds according to the rebound degree Rs of the concrete surface is measured by the sensor. . The amount of rebound measured by the sensor is converted into the rebound degree Rs of the concrete surface by the signal processing circuit and transmitted to the apparatus main body 12 as measurement data of the repulsion degree Rs via the communication line.
[0080]
When the measurement data of the rebound degree Rs of the concrete surface is received from the concrete test hammer 14, the apparatus main body 12 affirms the determination of step 82 and proceeds to step 84, and the neutralization depth C of the concrete at the measurement location is determined. The operator requests the operator to measure the neutralization depth C by, for example, displaying a message requesting measurement of the above on the display 12A. In the next step 86, it is determined whether or not the measurement data of the neutralization depth C is input from the neutralization depth measuring device 16, and step 86 is repeated until the determination is affirmed.
[0081]
When the message displayed on the display 12A is confirmed, the operator performs an operation of measuring the neutralization depth C of the concrete at the measurement location using the neutralization depth measuring machine 16 (step 78). That is, as a preparatory work, first, it is confirmed whether or not the drill bit 40 is attached to the neutralization depth measuring device 16, and if the drill bit 40 is not attached, the drill bit 40 is attached. Next, it is confirmed whether or not the cartridge 32 is loaded in the main body 16A, and if it is not loaded, the cartridge 32 is loaded (screwed into the circular hole 30), and then the pressure mechanism provided in the cartridge 32 To pressurize the storage portion of the cartridge 32. Further, the perforation depth scale 50 is pulled out from the main body 16A and slid to the measurement start position. When the above-described preparatory work is completed, the tip of the drill bit 40 comes into contact with the concrete surface of the measurement location, and the main body 16A is held so that the drill bit 40 is perpendicular to the concrete surface, and this state is maintained. The measurement start of the neutralization depth C is instructed by turning on a switch not shown.
[0082]
As a result, the drill bit 40 rotates to start drilling the concrete at the measurement location, and the reagent is ejected from the vicinity of the tip of the drill bit 40, and the concrete powder attached to the groove 44 and discharged is changed to red. Is detected by the color change detection unit 52 (that is, when the hole drilled by the drill bit 40 reaches the non-neutralized portion of the concrete at the measurement location), the rotation of the drill bit 40 is stopped, The slide amount of the drilling depth scale 50 is transmitted to the apparatus main body 12 as measurement data of the neutralization depth C via the communication line.
[0083]
When the measurement data of the neutralization depth C is received from the neutralization depth measuring device 16, the apparatus main body 12 affirms the determination of step 86 and proceeds to step 88, and from the neutralization depth measuring device 16. The neutralization depth C represented by the received measurement data is compared with the formula (6) stored in the ROM. If 1 [mm] <neutralization depth C ≤ 5 [mm], surface hardness correction By calculating the coefficient β, a value corresponding to the neutralization depth C of the concrete at the measurement location is set as the surface hardness correction coefficient β.
[0084]
In the next step 90, the surface hardness correction coefficient β obtained in step 88 and the restitution degree Rs represented by the measurement data received from the concrete test hammer 14 are respectively substituted into the equation (7) stored in the ROM. Then, the modified rebound degree Ri corresponding to the repulsion degree inside the concrete (the part that is not neutralized) at the measurement location is calculated. In step 92, the corrected repulsion degree Ri obtained in step 90 is substituted into the equation (8) stored in the ROM to estimate and calculate the compressive strength Fc of the concrete at the measurement location. In step 94, the estimated value of the compression strength Fc obtained by the estimation calculation in step 92 is output by displaying it on the display 12A.
[0085]
Thus, in this embodiment, after measuring the rebound degree Rs and the neutralization depth C of the concrete surface at the measurement location, the surface hardness correction coefficient β corresponds to the neutralization depth C of the concrete at the measurement location. Since the rebound degree Rs of the concrete surface is corrected to the corrected rebound degree Ri corresponding to the repulsion degree inside the concrete using the value to be calculated, the compressive strength Fc of the concrete is estimated and calculated from the corrected rebound degree Ri. Thus, it is possible to obtain an estimated value of the compressive strength Fc that accurately represents the actual compressive strength Fc of the concrete without being affected by neutralization.
[0086]
In addition, the measurement of the resilience Rs using the concrete test hammer 14 only hits the concrete surface, and the measurement of the neutralization depth C using the neutralization depth measuring machine 16 is also neutralized. It is only necessary to drill a hole until an unexposed part appears, so it is not necessary to collect a concrete core from a building or the like for estimating the compressive strength Fc, and the compressive strength Fc is directly measured by a compression tester. Compared to the case, the influence on the building can be made very small.
[0087]
In the above description, as an example of the relationship between the neutralization depth C and the surface hardness correction coefficient β, the numerical value range of the neutralization depth C is divided into a plurality of classes, and mathematical expressions defining the surface hardness correction coefficient β Although the example (refer to Formula (6)) set for each class has been described, the present invention is not limited to this, and the relationship between the neutralization depth C and the surface hardness correction coefficient β can be expressed by a single formula, The neutralization depth C is related to the surface hardness correction coefficient β by expressing it in the form of a table or the like, and the surface hardness correction coefficient β is calculated from the neutralization depth C by using the above-described single equation or table. You may make it ask.
[0088]
Further, when the modified resilience Ri is obtained from the rebound degree Rs of the concrete surface and the surface hardness correction coefficient β, and when the compressive strength Fc of the concrete is obtained from the modified resilience Ri, the equations (7) and (8) It is not limited to using such an arithmetic expression, and it is also possible to use a table or the like (for example, a two-dimensional look-up table is suitable for obtaining the corrected repulsion degree Ri).
[0089]
Moreover, in the above, as an example of the concrete strength estimation apparatus according to the present invention, the concrete test hammer 14, the neutralization depth measuring device 16 and the apparatus main body 12 are connected by a communication line. Although explained, it is not limited to this, It is the structure which an operator inputs into the apparatus main body 12 the measured value measured by the concrete test hammer 14 or the neutralization depth measuring machine 16 manually. There may be.
[0090]
【The invention's effect】
As described above, the invention according to claim 1 is the surface portion in the concrete in which the surface portion is neutralized with respect to the degree of resilience of the surface portion of the concrete to be estimated for compressive strength measured using a concrete test hammer. The compressive strength of the concrete is estimated based on the relationship between the hardness of the steel and the non-neutralized internal hardness, and the compressive strength of the concrete is estimated based on the rebound after the correction. It has an excellent effect that it can be estimated with high accuracy.
[0091]
The invention according to claim 3 is characterized in that, in the invention according to claim 2, the surface hardness correction coefficient β as the relationship between the hardness of the surface portion and the internal hardness is set to the neutralization depth in the concrete where the surface portion is neutralized. In addition to the above effects, the estimation of the compressive strength of the concrete is performed by using the surface hardness correction coefficient β corresponding to the neutralization depth of the concrete to be estimated. There is an effect that the accuracy can be further improved.
[0092]
In the invention according to claim 7, in the invention according to claim 1, when the degree of resilience of the surface portion of the concrete is measured using a concrete test hammer, the surface portion of the concrete is brought into a wet state. In addition, it has the effect that the estimation accuracy of the compressive strength of concrete can be further improved.
[0094]
  Claim9In the described invention, the degree of resilience of the surface portion of the concrete to be estimated for compressive strength measured using a concrete test hammer is determined by the hardness of the surface portion of the concrete having a neutral surface portion and the neutrality of the surface portion. Since the correction means for correcting based on the relationship between the internal hardness and the estimation means for estimating the compressive strength of the concrete based on the degree of resilience after correction, the non-destructive test method, It has an excellent effect that the compressive strength of concrete can be estimated with high accuracy.
[0095]
  Claim 10The described invention is claimed.9In the described invention, the storage means for storing the surface hardness correction coefficient β in relation to the neutralization depth in the concrete having a neutralized surface portion, and the measurement means capable of measuring the neutralization depth of the concrete The provided and correcting means corrects the resilience of the surface portion of the estimation target concrete using the surface hardness correction coefficient β corresponding to the measured neutralization depth of the estimation target concrete. And, it has the effect that the estimation accuracy of the compressive strength of the concrete to be estimated can be further improved.
[0096]
  Claim 11The invention described in claim 10In the described invention, the measuring means is a perforation means capable of perforating concrete, a supply means for supplying a reagent to the concrete powder generated by the perforation, and a color change to concrete powder by the supplied reagent. In addition to the above effects, the neutralization depth can be easily measured in addition to the above effects.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a rebound degree Rs on a concrete surface and a Vickers hardness Hs at a depth of 1 mm from the concrete surface, obtained by an experiment conducted by the inventors of the present application.
FIG. 2 is a diagram showing a relationship between a neutralization depth C and a surface hardness correction coefficient β obtained by an experiment conducted by the inventors of the present application.
3A shows the relationship between the resilience degree Rs and the compressive strength Fc on the concrete surface, and FIG. 3B shows the estimated resilience degree inside the concrete (corrected resilience degree) obtained by experiments conducted by the inventors. It is a diagram which shows the relationship between Ri) and compressive strength Fc, respectively.
4A is a relationship between the rebound degree Rs and the compressive strength Fc on the concrete surface obtained by another experiment, and FIG. 4B is an estimate of the repulsion degree inside the concrete estimated from the repulsion degree Rs of FIG. It is a diagram which shows each the relationship between a value (correction repulsion degree Ri) and compression strength Fc.
FIGS. 5A to 5C are diagrams showing the relationship between the modified resilience Ri and the compressive strength Fc obtained by experiments conducted by the inventors of the present invention for each moisture treatment condition on the concrete surface. .
FIG. 6 is a schematic configuration diagram of an intensity estimation apparatus according to the present embodiment.
FIG. 7 is a schematic diagram illustrating a schematic configuration of the neutralization depth measuring machine with a part thereof broken.
FIG. 8 is a flowchart showing work performed by an operator and processing performed by the strength estimation device in estimating the compressive strength of concrete.
FIG. 9 is a diagram for explaining the estimation accuracy in the conventional method for estimating the compression strength Fc from the repulsion degree Rs.
[Explanation of symbols]
10 Strength estimation device
12 Device body
14 Concrete test hammer
16 Neutralization depth measuring machine

Claims (11)

Measure the resilience of the surface of the concrete whose compression strength is to be estimated using a concrete test hammer,
Based on the relationship between the hardness of the surface portion and the internal hardness that is not neutralized in the concrete having a neutralized surface portion, the degree of resilience of the surface portion of the concrete to be estimated is corrected,
A concrete strength estimation method for estimating the compressive strength of the estimation target concrete based on the rebound degree after correction.   As the relationship between the hardness of the surface portion and the internal hardness, a surface hardness correction coefficient β corresponding to the ratio of the hardness of the surface portion and the internal hardness in the concrete in which the surface portion is neutralized is used. The concrete strength estimation method according to claim 1. The surface hardness correction coefficient β is related to the neutralization depth in the concrete where the surface portion is neutralized,
Measure the neutralization depth of the estimation target concrete,
The strength of the concrete according to claim 2, wherein the rebound degree of the surface portion of the estimation target concrete is corrected using a surface hardness correction coefficient β corresponding to the neutralization depth of the estimation target concrete. Estimation method.   When the neutralization depth C of the estimation target concrete is C ≦ 1 [mm], β = 1 is used as the surface hardness correction coefficient β, and the neutralization depth C is 1 [mm] <C ≦ In the case of 5 mm, β = 0.5 / C + 0.5 is used as the surface hardness correction coefficient β, and in the case where the neutralization depth C is C> 5 [mm], the surface hardness correction coefficient β is β = 0.6. The concrete strength estimation method according to claim 3, wherein: Using the surface hardness correction coefficient β, the modified resilience Ri corresponding to the resilience inside the concrete to be estimated,
Ri = β · Rs− (1−β) · b / a
The concrete strength estimation method according to claim 2, wherein the repulsion degree Rs of the surface portion of the estimation target concrete is corrected by calculation using the following equation (where a and b are constants).   6. The concrete strength estimation method according to claim 5, wherein a = 1.82 and b = -36.2 are used as the constants a and b of the arithmetic expression.   The surface of the concrete to be estimated for measuring the degree of repulsion is wetted when the degree of rebound of the surface of the concrete to be estimated for compressive strength is measured using a concrete test hammer. Item 2. A method for estimating the strength of concrete according to Item 1. The concrete strength estimation method according to claim 7, wherein the surface portion is made wet by spraying water on the surface portion of the estimation target concrete or supplying water for a predetermined time or more. The repulsion degree of the surface part of the concrete for which the compressive strength is measured using a concrete test hammer is used to determine the hardness of the surface part and the internal hardness of the concrete part. Correction means for correcting based on the relationship between
Estimating means for estimating the compressive strength of the estimation target concrete based on the degree of rebound after correction by the correcting means;
Concrete strength estimation device including As the relationship between the hardness of the surface portion and the internal hardness, a surface hardness correction coefficient β corresponding to the ratio of the hardness of the surface portion and the internal hardness in the concrete in which the surface portion is neutralized, Storage means for storing in relation to the neutralization depth in the neutralized concrete;
A measuring means capable of measuring the neutralization depth of the estimation target concrete;
The correction means corrects the resilience of the surface portion of the estimation target concrete using a surface hardness correction coefficient β corresponding to the neutralization depth of the estimation target concrete measured by the measurement means.
The concrete strength estimation device according to claim 9. The measuring means includes
Drilling means capable of drilling holes in concrete;
A supply means for supplying a reagent to the concrete powder produced in association with the drilling of the hole by the drilling means;
Detecting means for detecting whether or not a color change has occurred in the concrete powder by the reagent supplied by the supplying means;
The concrete strength estimation apparatus according to claim 10, comprising:

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