【单选题】我国规范规定,用边长为( )的标准立方体试件,在标准养护条件下(温度20°C±3°C,相对湿度不小于90%)养护28d后在试验机上试压。试验时,试块表面不涂润滑剂,全截面受力,加荷速度约为0.15~0.25N/mm 2 /s。试块加压至破坏时,所测得的极限平均压应力作为混凝土的立方体抗压强度,用符号 f cu 表示,单位为N/mm 2 。
【简答题】Nancy and Peter McCall like sports. In the summer they swim and in the winter they ski. They are planning ski trip for this weekend, but they don't know about the weather. It's 7:30 now, and they are ...