Materials Testing Consultants has been providing pavement management and testing services on hundreds of MDOT local agency projects for many years. Along with services like asphalt engineering and surface evaluation, one of the services provided is the hot mix asphalt (HMA) mixture verification testing.
The purpose of the test is to verify the correct amount of asphalt cement and the gradation of the aggregates are within the specified tolerance of the job-mix-formula (JMF) submitted by the paving contractor and specified by the MDOT Special Provision of Acceptance of HMA Mixture on Local Agency Projects.
As with MDOT, many municipalities, road commissions and consultants incorporate similar requirements in their specifications. In general, the special provision requirements consist of obtaining two mixture samples per day per mixture and a minimum of three mixture samples per mixture type.
In addition to the MDOT Local Agency projects, MDOT’s trunk line projects generally contain HMA Percent Within Limits (PWL) special provisions. These added provisions specify a two- to four-day turnaround for testing and reporting of the mixture samples’ test results.
Unlike concrete, where many of the specified parameters can be tested in the field during placement, HMA mixture verification testing needs to be performed in the laboratory. At times, we can test the mixture in the plant’s laboratory. However, most testing is done in our own laboratory.
In understanding the needs and desires of our clients for prompt, accurate results, MTC has trained and certified more field technicians for field testing at the plant.
We have also hired and trained additional certified laboratory technicians for when a plant’s laboratory is unavailable and cast samples are required to be tested in-house.
We believe these changes have given the boost needed to exceed our client’s expected turnaround times in reporting test results.
Our continued goal is to provide rapid, accurate results to allow adjustments at the plant to be made quickly and efficiently to gain our clients’ confidence in test results and, in the long-term, provide better roads for us all.
