Abstract: A lightweight cementitious composite material includes expanded synthetic polymer particulate having a particle size of between 0.0625 and 0.5 inches. A dispersant coating on said particulate suppresses electrostatic attraction between particulate particles. A matrix surrounds the particulate and is present from 0.25 to 1 pound per gallon of dispersant coated particulate.

Abstract: The present invention provides an improved composite material structure having large portions of additive material aligned over a substantial width of a material structure and occupying a larger percentage of the structure volume. The material structure includes a resilient substrate layer or conventional decking having a plurality of elongated rods arranged on a surface of the substrate layer to form at least one rod layer. The spaces between rods are filled with a slurry material which is allowed to set causing the component elements to bond together to form a lightweight durable and high strength composite material structure.