Trr No. 1323 Materials And Construction, pp. 112-122
Asphalt concrete pavement layers are sometimes weakened by moisture when the adhesive bond between the aggregate the aggregate surface and the asphalt cement is broken. The problem of stripping, or disbonding of asphalt cement from aggregates in asphaltic concrete mixtures, has produced serious pavement distress, has increased pavement maintenance, and has resulted in poor pavement performance. Use of antistrip additive is often necessary to prevent stripping in asphaltic concrete pavements. The selection of an appropriate antistrip additive for a particular project is not an easy task because of the many factors involved. Most highway agencies perform tests on an asphaltic concrete mixture to determine its moisture-susceptibility performance. Som of these tests may include indirect tensile strength, resilient modulus test, boiling test, and moisture susceptibility tests (e.g., Lottman or Tunnicliff-Rot). The results obtained from some or all of these tests are used to determine the moisture susceptibility of a mixture. However, depending upon the agency or individuals involved,each test property may be evaluated differently. Therefore, fuzzy set theory is introduced for selecting the best-performance antistrip additive based on the performance of several asphaltic concrete mixture properties. The Tunnicliff-Root procedure was used to evaluate the effect of antistrip additives on the strength of 960 Marshall specimens. The average dry and wet indirect tensile strength ratio, visual stripping, and the price of the antistrip additives were used in a computer program developed to analyze the data using the fuzzy set theory. In this research project, it was shown that fuzzy sets can be successfully used for evaluating the effectiveness of antistrip additives in asphaltic concrete mixtures.