The key innovation in his work was the "wet" grinding of raw materials, which became fundamental to the early development of Portland cement.
He ground the soft local chalk together with alluvial clay from the Medway estuary and added water in a washmill to produce a thin slurry from which coarse particles could be removed by settling.
The fine, homogenous mixture of chalk and clay particles was dried to a stiff plastic consistency before being burned in a kiln.
Charles Pasley communicated frequently with Frost, and gave a detailed description of his techniques[2] based on a visit to Swanscombe in December 1828.
In 1832, he sold the Swanscombe plant to John Bazely White's, and migrated to New York City, where he set up as a civil engineer.