These databases will often provide index & abstracts to conference papers and proceedings, but you may have to apply through InterLibrary Loans for access to full text:
Academic Search Complete - is the world's most valuable and comprehensive scholarly, multi-disciplinary full-text database, with more than 8,000 full-text periodicals, including more than 6,300 peer-reviewed journals. In addition to full text, this database offers indexing and abstracts for more than 11,500 journals and a total of more than 12,000 publications including monographs, reports, conference proceedings, etc.
Compendex (Engineering Village) covers the following engineering areas: mechanical, civil, electrical, structural, chemical, bioengineering, energy, optics, materials science, optics, and pollution.
ICE Virtual Library is the most comprehensive online civil engineering resource in the world. Here the user can explore the full archive of the Institution of Civil Engineers back to 1836, browse their internationally renowned journals and books, and take advantage of their powerful searching tools to find the information one needs.
JSTOR offers multidisciplinary and discipline-specific collections that include complete runs of journals as well as select monographs, transactions, and conference proceedings
Papers First (OCLC) - This a database of OCLC index of papers presented at conferences worldwide
Proceedings (OCLC) - An index of worldwide conference proceedings
Scopus- is the largest abstract and citation database of peer-reviewed literature: scientific journals, books and conference proceedings
Zetoc - Mimas at the University of Manchester provides access to the British Library's Electronic Table of Contents of around 20,000 current journals and around 16,000 conference proceedings published per year.