Tsugio Nishimura

Properties and mechanical–environmental efficiency of concrete combining recycled rubber with waste materials

This paper investigated the effect of combining rubber crumbs with recycled aggregates and fly ash on the mechanical properties and environmental impact of concrete. Increasing the amount of rubber crumbs linearly reduced strength and Youngs modulus regardless of aggregate or binder type, but the effect of recycled aggregate on strength decreased as the amount of rubber crumbs increased. Air permeability also increased with the amount of rubber crumbs but the effect of recycled aggregates varied, as it was constant in the case of non-fly ash but completely reduced with fly ash. The mechanical–environmental efficiency was calculated by weighting the strength by the volume of raw materials, and recycled aggregates were found to have the highest efficiency whereas rubber crumbs were inefficient. When setting a specific strength level, the weighted strength could be used to select the most efficient combination of waste materials.

EVALUATION OF TIME-DEPENDENT PROPERTIES OF FIBER REINFORCED PLASTIC RODS

FRPロッドのプレストレストコンクリート用緊張材としての適用性を検討するための基礎的な研究として, ガラス繊維, アラミド繊維, 炭素繊維を用いたFRPロッドの疲労試験およびクリープ試験を行い, 平均応力, 応力振幅, 持続載荷応力の影響について検討するとともに, これら時間依存性を有する特性の破壊機構について検討を加えた. 疲労破断繰返し回数は平均応力および応力振幅の増大とともに減少し, ガラス繊維を用いたFRPロッドに対しては, 平均応力および応力振幅を用いることにより疲労破断繰返し回数を推定することが可能であることを示した. クリープによる破断時間は, 載荷応力の増大とともに減少するが, 応力比を用いることにより, 破断時間の予測が可能であることを示した.