Abstract: A composite load bearing structure comprises a main body portion having a top surface and a bottom surface defining a dimension of thickness therebetween, first and second side surfaces defining a dimension of width therebetween, first and second end surfaces defining a dimension of length therebetween, and a first longitudinal axis oriented along the length of the main body portion. The thickness is significantly less than at least the length of the load bearing structure. The main body portion is made of a first composite material comprising a binding constituent in a proportion of about 10% to about 20% by volume, and an aggregate material in a proportion of about 80% to about 90% by volume. The binding constituent comprises polyethylene or a polyethylene blend having at least 10% polyethylene.

Abstract: A composite railway tie, and process for manufacture thereof, is disclosed. The composite railway tie comprises a main body portion being made of a first composite material comprising a binding constituent in a proportion of about 10% to about 20% by volume, and an aggregate material in a proportion of about 80% to about 90% by volume. The binding constituent comprises a plastic material chosen from the group of polyethylene and a polyethylene blend having at least 10% polyethylene. The aggregate material is in the form of irregular multi-faceted pieces chosen from the group consisting of crushed furnace slag, crushed gravel, crushed limestone, crushed granite, crushed basalt, and crushed trap rock, and mixtures thereof. The pieces of the aggregate material are distributed and otherwise arranged within the main body portion of the second material so that opposed surfaces of the pieces of the aggregate material have at least partial contact, one with another, in a contiguous manner.