Non-destructive ultrasonic evaluation of construction variability effect on concrete pavement performance

It is commonly recognized that non-uniformity of as-constructed Portland Cement Concrete (PCC) pavement may negatively affect long-term pavement performance. Conventional wisdom states that PCC thickness deficiency is the most important factor causing premature pavement failures. To address it, transportation agencies often impose strict penalties for not meeting the designed slab thickness requirements, thus contractors build slightly thicker slabs to avoid fines. However, other aspects of construction variability on pavement performance are mostly ignored by studies because conventional methods for construction uniformity assessment fail to provide sufficient information to quantify their effect. This study utilized a non-destructive ultrasonic test to evaluate in-situ pavement construction variability. To investigate the correlation between construction variability and surface distresses, a combination of non-destructive ultrasonic thickness measurements and visual distress surveys were performed in highways prior to rehabilitation. PCC slab thicknesses and shear wave velocities were computed from recorded ultrasound signals. An in-depth statistical analysis was performed to investigate possible relations between thickness or shear wave velocity and distresses using various pavement performance parameters. The main results of this analysis illustrate the importance of material quality and uniformity control during construction, since alterations in material properties significantly influence the presence of distresses. Shear wave velocity variations significantly correlate to cracked and broken slab panels in two sections, and, more importantly, to any type of distress in all tested pavement sections.