Trr No. 1171 Asphalt Materials And Mixtures, pp. 1-11
The basis for using mechanical property ratios to predict moisture sensitivity in asphalt concrete is discussed. Initial test data from the mositure damage test sections of NCHRP projects 4-8(3)/1 and 4-8(4) are used in two relative life mechanistic models developed to predict wet performanc e lives. Periodic core properties obtained during a 10 year period are used to evaluate in situ wet lives of the test sections. Comparisons indicate that predicted lives and in situ lives are similar. Implications are that additional built in complexity in moisture damage models may not be needed in the near future. Control of moisture damage is more reliably achieve through the application of both indirect tensile strength and resilient modulus cutoff ratios, which are readily calculated from prediction models. These ratios are dependent on strength and modulus test data, pavement location, and performance requirements. There is reason to think that a high reliability of zero moisture damage can be achieved in the field when cutoff ratios are exceeded