Determination of Flow Number in Asphalt Mixtures from Deformation Rate during Secondary State

Abstract

Numerous research studies have been conducted on the connection between asphalt material properties and pavement performance. Asphalt mixture performance tests (AMPTs) have been part of these efforts in the past few years. One such test is the flow number test, the output of which is the flow number. Recent studies have found that flow number correlates well with the rutting potential of asphalt pavement. However, the current method used in AMPTs to examine the flow number also was highly sensitive to the variation of testing data (resulting in inaccurate flow number values) and time-consuming, especially when used on stiff asphalt mixtures. The main goal is to determine the flow number with the use of the deformation rate at the secondary state from the result of the flow number test. One hundred twenty-two flow number tests were conducted. A stepwise method was used to overcome variations in results from the flow number test. The flow number was determined with the stepwise method, then compared with the flow deformation rate. A strong correlation between flow number and deformation rate was found. Therefore, the deformation rate can be used to estimate flow number, which significantly reduces testing time. The proposed method also allows the flow number test to be terminated as soon as the permanent strain reaches 1.2%.