释义 |
> as lemmascement royal hydraulic cements harden under water, and are used for piers, dock-walls, etc. Roman cement, like all the hydraulic cements, is an argillaceous lime. Portland cement is so called because it resembles in colour the Portland stone. It is prepared by calcining a mixture of the clayey mud of the Thames with a proper proportion of chalk (Ure). Also cement royal.< |