国産針葉樹材を用いたコンクリート型枠用合板の単板構成と曲げ性能の検討

摘要

Bending performances of Concrete-form plywood were evaluated and the effects of veneer layups were discussed. Sugi (Cryptomeria japonica D.Don), Hinoki (Chamaecyparis obtusa Endl.) and Karamatsu (Lalix leptolepis Gordon) were chosen for the species of the veneers and 12 mm-thick and 15 mm-thick plywood were manufactured and tested according to the JAS standard for plywood. The results were summarized as following:1)MOR of 20～60MPa and MOE of 6.2～11GPa in strong-axis were observed and all plywood meet the requirements in JAS standard. 2) The density of plywood using Sugi was relatively lower than those of other species. 3) The range of bending performances of Sugi plywood was estimated by parallel ply theory and MOE of 8.58～3.84 GPa and MOR of 39.9～17.9 GPa in major-axis, MOE of 5.24～0.509 GPa and MOR of 29.3～6.13 MPa in minor-axis was obtained, assuming veneer MOE as 9.09 GPa and MOR as 42.3 MPa.%試作した合板は全て型枠用合板のJAS規格基準値を満足しており，スギ等の地域材を一部または全層に使用しても要求性能を満たす合板が製造可能であること力が確認できた。特にスギを用いると合板の密度が低くなり，現場での施工性が向上することは大きな利点と考えられる。