Results are given of fatigue tests under direct stress axial loading conditions on a typical rolled asphalt base-course material, to investigate the significance of varying the load-time history. Rest periods between successive loading cycles had a beneficial effect on fatigue performance, both by increasing the resistance to cracking and by reducing the rate of loss of dynamic stiffness due to repeated loading. Rest periods of the order of 1 s increased the number of cycles to failure by a factor of up to 25, when compared with the life under continuous sinusoidal cyclic loading. The improvement in life was less at high temperatures; it also appeared to be affected somewhat by the magnitude of the applied cyclic stress, although this effect was not clearly established. A comparison of fatigue performance under square, sinusoidal and triangular waveforms compared with the effects of rest periods. (Author/publisher)
Samenvatting