National Concrete Pavement Technology Center

Project description

Thickness is currently a pay item for PCC pavements and a quality control item for both PCC and HMA pavements. A change in pavement thickness of 0.5 in. can result in a change of multiple years of service. Current thickness measurements are performed by destructively coring the finished pavement and measuring the thickness of the core. Many times this is performed at the end of the project construction and only five representative samples are collected for each lot. Devices such as the MIT-SCAN-T2 are excellent examples of non-destructive technology capable of accurately measuring the pavement thickness. The objective was to evaluate the MIT-SCAN-T2 as a non-destructive pavement thickness measuring device for quality control and quality assurance purposes. A ruggedness study was performed in the laboratory to determine factors of influence on thickness measurements. Field evaluations were performed to test the device in actual production conditions. The ruggedness test showed the presence of steel-toe boot, surface area, plate manufacturer, and depth as potentially significant factors. However, the influence of these factors on the measured depth was large, causing significant errors in the depth readings. An additional factorial was performed with a control sample and additional runs, varying only one factor at a time. The readings obtained with this factorial were significantly more accurate, with an error of 0.2 in. for the control sample. These results show that the device is capable of accurately measuring thickness if used within the parameters recommended by the manufacturer. The field results support the finding of the ruggedness study. If all of the negative influencing factors are controlled the MIT-SCAN-T2 can accurately measure the in-place depth of pavement. If any of these factors are present, then results can be skewed heavily.