macadam

Concise Oxford English Dictionary © 2008 Oxford University Press:
macadam /məˈkadəm/

▶noun broken stone used in compacted layers for surfacing roads and paths, typically bound with tar or bitumen.

– derivatives
macadamed adjective,
macadamized (or macadamised) adjective.

– origin C19: named after the British surveyor John L. McAdam.