Durability assessment of carbonated concrete in terms of water transport properties

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23562
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0304:Architecture, building engineering, and related fields
• Research Institution: Building Research Institute
• Principal Investigator: NAKADA Kiyofumi 国立研究開発法人建築研究所, 材料研究グループ, 研究員 (40848941)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: 中性化 / 炭酸化 / セメント硬化体 / 水分移動特性 / 水分保持特性

Outline of Final Research Achievements

Experiments were conducted on hardened cement, which is considered to have a dominant effect on neutralization (carbonation) and water movement in reinforced concrete members, and the following results were obtained. (1) The water content at equilibrium decreases with carbonation, and the equilibrium water content curve after neutralization may have a similar shape regardless of the water-powder ratio or cement type. The equilibrium moisture content curve may have a similar shape regardless of the water-powder ratio or cement type. (2) The moisture diffusion coefficient changes with the degree of carbonation, and this change can be evaluated by a single equation using the pore structure as an index.(3) Microcracks generated on the surface of the hardened cement during the accelerated carbonation process do not have a significant effect on the moisture diffusion coefficient. In addition to the above, the effect of carbonation on the water absorption rate was also investigated.

Free Research Field

コンクリートの耐久性

Academic Significance and Societal Importance of the Research Achievements

コンクリートの水分移動特性・水分保持特性に与える中性化の影響については，鉄筋腐食の進行速度と密接な関係があると考えられることから，本研究の成果は中性化を受けた鉄筋コンクリート造部材の耐久性評価に資する基礎的知見であると考えられる。また，中性化と水分移動特性・水分保持特性の変化の関係については，これまで十分な検討がなされておらず，なぜこのような変化が生じるのかについて議論の途上にあると言える。本研究では，この変化の原因について空隙構造およびひび割れの観点から検討を行い，空隙構造に関わる指標によりこの変化を評価できる可能性を示した点で学術的意義を有するものと考えられる。