As deterioration of concrete occurs on large concrete structures, repair and future preventative action depends on a thorough understanding of the cause of the failure. RJ Lee Group (RJLG) has leveraged extensive petrography experience to analyze concrete failures and identify their causes. This skillset enabled RJLG to assist a parking garage manager protect the facility.  Visual observations, optical microscopy, and scanning electron microscopy with energy dispersive X-ray microanalyses have all contributed to the forensic investigation. Through source determination of the failure, RJLG provided the facility manager with the information necessary to effectively repair or replace the damaged cement.