June 29, 2023 1:00 pm
Reid W. Castrodale, Ph.D., P.E., Castrodale Engineering Consultants, PC
FHWA’s Lightweight Concrete Bridge Design Primer – ABC Applications - pdf of presentation
- Lightweight Concrete Bridge Design Primer, FHWA-HIF-19-067, November 2021 - link to download a free copy from the FHWA website
Q&A Session - pdf
News - June 29, 2023 - pdf of presentation
Description: Using lightweight concrete reduces the weight of large precast concrete elements often used for ABC projects. This saves project costs by reducing equipment requirements for handling, transporting, and erecting ABC elements. Using lightweight concrete also allows use of fewer, larger elements which avoids joints in a structure; allows reuse of existing substructure elements; avoids driving additional piles; allows reuse of substructure elements; and reduces seismic demands. However, some bridge engineers are reluctant to use lightweight concrete. This presentation introduces the FHWA Lightweight Concrete Bridge Design Primer that addresses engineers’ concerns by providing the full range of information needed to use lightweight concrete in bridges. The document provides: an introduction to lightweight aggregate and lightweight concrete; information needed for design, including costs and recent revisions to the AASHTO LRFD Bridge Design Specifications that improved design using lightweight concrete; guidance for specifying and field use of lightweight concrete; and examples of bridges incorporating lightweight concrete.
Reid W. Castrodale, Ph.D., P.E.
Castrodale Engineering Consultants, PC
Email: reid.castrodale @castrodaleengineering.com
Reid, an engineering consultant, has worked as a bridge engineer at a design firm and at the Portland Cement Association. He is a Fellow of the Precast/Prestressed Concrete Institute (PCI) and has served in managing technical editor roles for ASPIRE magazine since 2014 and as the Bridge Consultant for the Georgia/Carolinas PCI since 1997. Reid has given and continues to give prestressed concrete bridge design seminars across the country since the PCI Bridge Design Manual was introduced in 1997. He has worked in the lightweight aggregate industry since 2005 and has authored the Lightweight Concrete Bridge Design Primer for FHWA as a subconsultant to WSP. He has degrees from Georgia Tech and the University of Texas at Austin.
1) Structural lightweight concrete is a manufactured product that has been used in US since 1920, so it is not a new product. An early use of lightweight concrete in bridges was the upper deck of the San Francisco Oakland Bay Bridge, which used all-lightweight concrete (95 pcf air-dry) and is still in service today.
6) An example of the information provided in the Primer regarding the properties of lightweight concrete. Data shown indicates that the creep and shrinkage for a lightweight concrete mixture are less than values for a similar normal weight concrete mixture, both being high strength concrete mixtures intended for use in pretensioned girders.
7) One of the examples provided in the Primer of a bridge project where lightweight concrete was used in an ABC application. In this case, lightweight concrete was used to reduce the weight of the prefabricated girder/slab units for two similar ABC superstructure replacement projects in Richmond, Virginia.