The use of the indirect tensile test to investigate the effects of ethylene vinyl acetate, polypropylene fiber, rubber, and sulfur as additives on the fatigue and strength characteristics of bituminous mixtures is discussed. The test apparatus, preparation of specimens, and selection of binder contents using the Marshall prodecure aredescribed. Experimental results on the effects of stress level, binder content, and additive on the mean load cycles to failure are given and compared with the work of other investigations. Relationshipsbetween fatigue life and applied stress difference are developed and compared with experimental results. The addition of additives in most cases increased fatigue life; significant improvements were observed when the bitumen incorporated ethylene vinyl acetate and when a50/50 sulfur/bitumen blend was used. Some improvement in fatigue properties was noted for rubber-modified mixes and 20/80 sulfur/bitumen mixes. Fiber-reinforced specimens had lower fatigue lives because of sample preparation difficulties.(A).
Samenvatting