Meridian Hill Park has been designated a National Historic Landmark in large part because of its incredible concrete. The Park is the birthplace of gap-graded, exposed aggregate, architectural concrete. Architectural sculptor John J. Earley invented this remarkable material for the Park’s initial construction in 1915. Earley Studio created dozens of unique mosaic effects in the Park by combining pebbles of many sizes and colors in the concrete mixtures. John Earley’s innovations sparked the worldwide adoption of exposed aggregate concrete for architectural finishes.
After decades of inconsistent repairs, the National Park Service sought a comprehensive process to restore and replicate the Park’s distinctive concrete. The Armbruster Company analyzed the original concrete mixtures, located matching aggregates, developed 18 new concrete mixtures, produced samples, and wrote specifications for the concrete materials, mixtures and repair methods. Next, Mr. Armbruster directed the reconstruction of a pier to demonstrate that the materials and procedures could successfully replicate the historic concrete.
The Armbruster specified process has been used effectively for phased restoration of concrete elements throughout the Park and will guide future generations of architects and craftsmen in their preservation work.