Pavement Preservation Journal, Winter 2013, Vol. 6, No. 4
After a hiatus of several decades, Florida DOT once again is employing hot in-place recycling (HIR) with simultaneous hot mix asphalt overlay, this on U.S 41, the Tamiami Trail, a process known as repaving.
There, late last season, about 35 miles west of Miami, four miles of the Tamiami Trail was hot in-place recycled with virgin HMA overlay, from mile posts 0.00 to 3.9, with 12-ft. driving lanes each way. In addition, two 4-ft.-wide shoulders were overlaid monolithic with the pavement. Before this work, both the existing pavement and shoulders were milled of their open-graded friction course 1-in. deep.
For this work Florida DOT applied a “developmental specification,” which permits use of a new or unique process. Dev 325 permits “[Construction of] a repaved asphalt concrete pavement by milling and constructing a binder course layer and friction course layer using a paving machine capable of recycling the existing asphalt using the hot-in-place process and placing plant-produced virgin hot-mix asphalt simultaneously.”
“This was a brand-new spec,” said John S. Fowler, P.E., quality assurance engineer for Florida DOT. “During our previous era of recycling we used one spec for surface recycling, and it did not permit the repaving method used here. After seeing a couple of demonstrations we wanted to open the competition up to other processes, so we wrote a brand-new spec that permitted the HIR repaving process.”