Keywords: special OGAB, multiple cracking, concrete surfacing, OGAB test cell, open graded aggregate base, drainability, gradation change, IRI, International Roughness Index, forensic evaluation, forensic engineering, limestone aggregate base, early failure
Forensic evaluation of multiple cracking of a concrete test cell built over an open graded aggregate base
In August 2011 a test cell of 6 inch thick concrete surfacing placed over of special open graded Limestone aggregate base predominantly 8 inches (203 mm) thick was constructed at the MnROAD research facility. The two layers overlaid an existing 6 inch (150 mm) of MnDOT non–drainable aggregate base that overlaid a clay/silt sub–grade. In July 2012, an extensive cracking pattern was observed. This paper discusses data analysis, semi–destructive testing investigations and design re–examination to ascertain cause(s) of the premature distress. The litany of test results suggested possible loss of support from the special Open Graded Aggregate Base (OGAB).