The Special Features of Cement Standards in China

Abstract

Abstract A large amount of blended cement, special cement, and shaft kiln manufactured cement is produced in China. These cements form the basis for China's cement standards. These standards have many special features and constitute a unique cement standard system. The standard cements are divided into three groups: common cement, special performance cement, and special purpose cement. As common cements, which include ordinary portland cement, portland blast-furnace cement, portland pozzolana cement, and portland composite slag cement, etc., the required and allowable blended materials incorporated in their specifications are somewhat like those in the European cement standard EN V 197, but some kinds of metallurgical slags are allowed into composite portland cement to make good use of industrial wastes, and a series of strength grades (including type R, which have higher early strength criteria) are stipulated for satisfying the various technical level of cement production and the different construction requirements. As to the special performance cement group, there are several series of cements such as portland cement, aluminatc cement, sulfo-aluminate cement, and ferro-aluminate cement, etc. The specifications for these cements are characteristic of their performance requirements: moderate-heat portland cement stipulates the criteria for heat of hydration; rapid-hardening aluminate cement defines criteria for strength within three days; expansive sulfo-aluminate cement requires criteria for rate of expansion; and self-stressing ferro-aluminate cements need criteria for self-stressing values, etc. In addition, oil well cement and masonry cement, etc., belong in the special purpose cement group. A graphical standards system is presented which includes fundamental standards, product standards, and test method standards. Owing to the different strength of the test methods, the cement strength value cannot be compared between different countries. The author suggests an international cooperative test program be organized for establishing the interrelation of mortar strength between different testing methods and the ISO method to facilitate international trade and to exchange information.