Structural Engineering

Bridges Of The Nineteenth Century
Science, Technology, Structural Engineering, Bridge - Digital Bridges. Online library of historical bridge design manuals and books from Lehigh University.
http://bridges.lib.lehigh.edu/
PCA - The Portland Cement Association
Based in Skokie, Ill., the Portland Cement Association represents cement companies in the United States and Canada. It conducts market development, engineering, research, education, and public affairs programs.
https://www.cement.org/