Lightweight structural members

A lightweight structural member comprising:

• a first tubular member having a tubular configuration, wherein the first tubular member is characterized by interior and exterior surfaces;
• a second tubular member having a tubular configuration, wherein the second tubular member is characterized by interior and exterior surfaces;
• and
• foam material comprising hollow fly ash particulate material, an agglomerating agent and a metallic matrix material, wherein the agglomerating agent agglomerates individual particles of fly ash into agglomerated particles larger than the individual particles;
• wherein at least one member of the group consisting of the first tubular member and the second tubular comprises a metallic material;
• wherein the interior surface of the first tubular member is of such size and configuration and the exterior surface of the second tubular member is of such size and configuration as to permit disposition of the second tubular member within the first tubular member, thereby defining an annular volume between the interior surface of the first tubular member and the exterior surface of the second tubular member;
• and
• wherein the foam material fills at least a portion of the annular volume.

A method for manufacturing a lightweight composite member, comprising the steps of:

• providing at least a first metallic tubular member having tubular configuration, the first tubular member being characterized by interior and exterior surfaces, the interior surface defining an internal volume of the first tubular member therewithin;
• and
• filling at least a portion of the internal volume with a foam material, wherein said foam material comprises hollow fly ash particulate material, an agglomerating agent and a metallic matrix material, said fly ash particulate material comprising a bed thereof;
• and
• wherein the agglomerating agent agglomerates individual particles of fly ash into agglomerated particles larger than the individual particles.