The Texas Department of Transportation (TxDOT) has adopted QC/QA specifications for hot mix asphalt (HMA) projects. Under these specifications, the contractor is responsible for the HMA design and testing for pay-factors. The testing and pay-factors are broken into three areas: mixture, pavement density and smoothness. The contractor is also required to have a QC program to monitor the non-pay items of the job mix design. The contractor uses the data to make the decision to proceed, make corrections or shut down. The area TxDOT office is responsible for testing split samples taken by the contractor for acceptance. The TxDOT district laboratory is responsible for independent assurance samples. TxDOT, Division of Materials and Tests in Austin has been designated as the referee laboratory to settle any testing disputes not solved at the area office level.
This paper will summarize the construction of three QC/QA projects across Texas. The projects include Highway projects in Abilene and San Antonio and a project on I-20 near Eastland. The HMA used on these projects included a number of asphalt types and mixture designs. The projects used both polymer modified and conventional asphalts. The mixes used included both a dense graded surface mix as well as a coarse matrix high binder (CMHB) mix. The paper will also cover the problems and successes of mix design, testing which included using a nuclear asphalt content gage and communications.