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兼松 学*; 丸山 一平*; 野口 貴文*; 飯倉 寛; 土屋 直子*
Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.154 - 158, 2009/06
被引用回数：70 パーセンタイル：97.58(Instruments & Instrumentation)Improving the durability of concrete structures is one of the ways to contribute to the sustainable development of society, and it has also become a crucial issue from an environmental viewpoint. It is well known that moisture behavior in reinforced concrete is linked to phenomena such as cement hydration, volume change and cracking caused by drying shrinkage, rebar corrosion and water leakage that affect the durability of concrete. In this research, neutron radiography was applied for visualization and quantification of water penetration into concrete through cracks. It is clearly confirmed that TNR can make visible the water behavior in/near horizontal/vertical cracks and can quantify the rate of diffusion and concentration distribution of moisture with high spatial and time resolution. On detailed analysis, it is observed that water penetrates through the crack immediately after pouring and its migration speed and distribution depend on the moisture condition in the concrete.
丸山 一平*; 兼松 学*; 野口 貴文*; 飯倉 寛; 寺本 篤史*; 早野 博幸*
Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.159 - 162, 2009/06
被引用回数：32 パーセンタイル：88.55(Instruments & Instrumentation)In high-strength concrete with low water-cement ratio, self-desiccation occurs due to cement hydration and causes shrinkage and an increased risk of cracking. While high-strength concrete has a denser matrix than normal-strength concrete, resulting in lower permeability, early-age cracks would cancel out this advantage. For the mitigation of this self-desiccation and resultant shrinkage, water saturated porous aggregate, such as artificial lightweight aggregate, may be used in high-strength concrete. In this contribution, for the purpose of clarification of the volume change of high-strength concrete containing water-saturated lightweight aggregate, water transfer from the lightweight aggregate to cement paste matrix is visualized by neutron radiography. As a result, it is clear that water was supplied to the cement paste matrix in the range 3-8 mm from the surface of the aggregate, and the osmotic forces may yield water transfer around lightweight aggregate in a few hours after mixing.
兼松 学*; 野口 貴文*; 丸山 一平*; 飯倉 寛
コンクリート工学年次論文集(DVD-ROM), 29(1), p.981 - 986, 2007/00
非破壊可視化・定量化技術の一つである中性子ラジオグラフィを用い、コンクリートのひび割れ中の水分挙動の可視化及び定量化を目的とした基礎的な研究を行った。ペーストを用い本手法の定量精度確認した後、ひび割れ部の水分挙動の可視化を試みた。その結果、ひび割れ部及びマトリクス中に移動する水分挙動を高解像能で可視化・定量化可能であることが明らかとなった。
土屋 直子*; 兼松 学*; 野口 貴文*; 飯倉 寛
no journal, ,
近年鉄筋コンクリートの長寿命化が望まれており、そのため鉄筋コンクリートの耐久性能に強くかかわるコンクリート中の水分状態の精緻な評価が必要である。既往の水分定量化手法に比べて高解像能で非破壊測定が可能な中性子ラジオグラフィ装置を用いた水分定量化はコンクリート分野において有用である。そこで中性子ラジオグラフィを用いたコンクリート中の水分定量化手法として骨材・ペースト体積比を考慮した定量化手法の提案を行った。
