Prime Coat Calculations for IDOT

About a year ago, the Illinois Department of Transportation (IDOT) changed the way they measure & pay for bituminous prime coat. What used to be a simple computation became complicated (just like everything in construction anymore….). The specification requirements were expanded, increasing the degree of surface prep, cleaning & application parameters than with former specifications. IDOT made the change in response to research that has shown the expanded role that prime/tack coats play in the longevity of HMA overlays.

With the new Special Provision (CLICK HERE FOR A COPY), payment calculations also changed. Instead of paying for the total quantity of emulsion applied (in either gallons or pounds of emulsion), IDOT now pays for the residual asphalt (or the actual quantity of bitumen) This requires that the engineering calculate and subtract ALL water (both dilution water AND water in the emulsion) from the volume of of material that was shipped & applied.

OK, so I’m a pretty capable guy. I like to occasionally geek-out on spreadsheets. But for whatever reason, this one was a doosy. Developing formulas, based on the Bill of Lading (as it was shipped to the plant) and then developing respective formulas for the actual delivery was quite tedious. But, with effort comes results. I think I got it.


If you are interested in getting a copy of this worksheet, send me an email link in the COMMENTS below and I’ll try to help you out.


Please follow and like us:


  1. Looks like a great work sheet. Appreciate that you are willing to share it. BTW, your blogs have been very interesting. Great job!

  2. Bob, I am a young Resident Engineer and was referred to your blog from a past manager. I have found the material to be extremely well written and a valuable resource to me. I would really appreciate a copy of this worksheet for it would be a great tool for me in the field. Thank you and I look forward to the blogs to come!

Leave a Reply

Your email address will not be published.