Deck Condition Survey I-95 over Union Street

An automated sonic/ultrasonic data acquisition system pictured below was used to acquire nondestructive bridge deck testing data in the center lane of I-95 over Union Street in Norwood, Massachusetts. The bridge is a three span 107 foot long steel stringer bridge with an 8 inch thick reinforced concrete deck and a 2 to 3 inch thick asphalt wearing surface. Four parallel lines of NDT data were acquired for 100% NDT survey coverage of the area. NDT survey results identified upper deck deterioration/ partial deck repairs in all the areas subsequently repaired. Repair areas were identified by traditional chain dragging methods after the asphalt wearing surface was removed. NDT results identified approximately 240 square feet for partial deck repair. Approximately 200 square feet of the area tested was partial deck repaired.

The deck testing system uses an automated impact energy source, with four sensors (three linear and one diagonally from the source), to evaluate internal deck concrete conditions on bridges with and without asphalt wearing surfaces. Data are acquired at one foot intervals along a series of parallel survey lines the length of the bridge. Typically approximately 60% of the bridge surface is tested.

Sonic/ultrasonic pulse velocity and pulse echo data are recorded simultaneously and used to evaluate the strength of the concrete and to identify internal delaminations, cracking etc. Direct and refracted compressional and shear wave velocity measurements are used to calculate the concrete deformational moduli values (Young’s, shear, bulk) and strength. Reflection/resonant frequency measurements, which are recorded simultaneously, are used to detect delaminations, and decomposed zones.