Title:
Lessons from Post-tensioned Grouting Problems
Author(s):
Soundar Sriram Balakumaran
Publication:
Web Session
Volume:
ws_S24_SoundarBalakumaran.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
3/24/2024
Abstract:
The Lord Delaware and Eltham Bridges, constructed in 2006 and 2007 using post-tensioned high-strength lightweight girders, carry traffic on US 33 over the Mattaponi and Pamunkey Rivers. These similarly designed bridges were expected to last for over 100 years with minimal maintenance. However, during a routine inspection in 2015, a problem was discovered with one of the bridge beams. A spall in the beam's web exposed a tendon duct, raising concerns about the overall condition of the lightweight concrete girders. Michael Sprinkel's expertise in grout mixture behavior and the post-tensioning process led to a shift in the investigation's focus, identifying the grouted tendons as the source of the problems. Consequently, significant voids, soft grout, and free water were found in several of the girders, and concerns about potential strand corrosion arose. Nondestructive test methods, including Ground Penetrating Radar for tendon location and Impact Echo for grout evaluation, were employed to assess the condition of the tendons and grout. Destructive drilling and sampling techniques were also utilized to corroborate the Impact Echo findings and further evaluate the grout condition. Unfortunately, the design of the beams prevented access to the tendons at the anchors and over the piers, where voids are typically found. Consequently, suitable repair options were limited. However, this experience has prompted the implementation of stricter post-tensioning practices and quality assurance research initiatives in Virginia.