The Kansas Department of Transportation (KDOT) in cooperation with Kansas State University (KSU) and the American Concrete Pavers Association (ACPA) is developing an instrument capable of assessing tie bar placement accuracy suitable for use in a paving environment. The instrument is now in its fourth prototype. The third-generation prototype used a single magnetic sensor and was capable of assessing depth accuracy at a rate of approximately two miles of construction joint per hour on projects during the 2004 construction season. KDOT is developing a new placement specification appropriate for this type of sensing technology. The fourth-generation prototype will possess multi-sensor capability to assess lateral placement as well as depth accuracy. Due to cooperation with the ACPA, this instrument is targeted to be integrated into paving equipment for real-time quality control. This paper reviews the basic sensing principles of magnetic tomography and how it can be successfully integrated with microprocessors and communications into a nondestructive instrument for use in a concrete construction environment.
Abstract