strength grade of concrete

The deterioration is accelerated because the strength grade of concrete is too low, depth of cover too thin, and drain off water unsuitable.

调查表明，原设计混凝土标号过低，保护层过薄，桥面排水不当，加速了劣化过程。

The consequence of experiment indicates that the splitting tensile strength of steel fiber concrete increases with the increase of volume fractions, length-diameter ratio, the length and concrete strength grade. The cold drawn steel fiber is superior to the mill steel fibers and shear steel fiber.

研究表明：钢纤维混凝土劈裂抗拉强度随着钢纤维掺量、长径比、长度和混凝土强度等级的增长而增加，切断型钢纤维的增强效果要优于铣削型和钢带剪切型。

The results showed that: axial capacity increases with strength grade of concrete, pipe wall thickness, the type and number of layers of FRP and self-stressing.

结果显示：轴压承载力随着混凝土强度等级、钢管壁厚、FRP层数以及自应力的增大而增大。