Investigation of the Rapid Analysis Machine (RAM) for Determining the Cement Content of Fresh Concrete.

摘要

The Rapid Analysis Machine (RAM) is a semiautomatic means of determining the cement content of freshly mixed concrete. Developed in England, the RAM incorporates the concepts of particle behavior as a function of size and mass in its determination of cement content. Five minutes after an 8-kg sample of concrete has been introduced in the RAM, the cement content can be determined from a set of calibration curves. A series of typical concrete field mixtures was used to evaluate the RAM. These mixtures had cement contents ranging from 300 to 1000 lb/cu yd; several contained fly ash at a 30 percent replacement rate by volume, and one contained an admixture which entrained a total air content of 6 percent. The actual RAM unit evaluated could detect and determine the cement content to within + or - 12.3 percent of the original cement content. It was found that air-entrained concrete must be treated differently before testing to ensure that the results have been affected by the entrained air bubbles. (Author)