Checking it off
May 30, 2012
Clear up the stack at the plant – check; get through a one-hour "hot stop" – check; improve workability - check; easily make density – check…..that's the way to use Evotherm WMA on a project. Branscome Eastern Shore tried Evotherm WMA to improve the workability and appearance of their 9.5-mm mix with PG64-22 and 30% RAP, for which they have a Virginia DOT contract. When using a foam technology, the mix was typically delivered to the jobsite at 280-285 F where the paving crew complained that it was "gummy" and difficult to work.
With weather in the upper 50's and gusty winds, Branscome produced the mix at 255-265 F. As the mix temperature was lowered, the parallel-flow drum plant's stack became completely clear. An electrical switchgear problem caused an hour-long "hot stop". The operator noted that this was usually a problem running hot mix or foamed mix asphalt, but using Evotherm the plant resumed production without problems or wasted mix.
At the jobsite, mix temperatures averaged 240-255 F. The paving crew noticed a large improvement in workability of the mix compared to foamed mix. They were able to easilty rake and shovel the mix at 240 F. The paving foreman questioned if this was the same 30% RAP mix, noting the smooth, dense, shiny mat texture and the invisibility of handwork after rolling.
The Virginia DOT project inspector was also pleased with the results. Branscome achieved density with minimal effort of one vibratory pass and 2-3 static passes from two rollers.
Author: Bryan Pecht