Specimen size effect on dynamic modulus measurement of Cold recycled and full depth reclamation mixtures

Abstract

Dynamic modulus was measured using large-scale (LS) and small-scale (SS) specimens of four cold recycled (CR) and one full depth reclamation mixtures. The study found emulsified mixtures showed similar and repeatable dynamic modulus (E*) results with both specimen geometries (<15% difference) and foamed mixtures showed poor agreement between specimens (>24% difference), likely due to the differences in the mix matrices. The mechanistic-empirical pavement design analysis showed that E* differences in LS and SS of CR mixtures with foam resulted in error in asphalt concrete (AC) rutting predictions for sections with a thin surface layer (25 mm [1 in.]) and did not affect rutting predictions once the surface layer thickness was above 76 mm (3.0 in.). An empirical SS to LS shift factor method is presented.