Knowing that springback amount of bending material in bending dies is as important as the die itself, because the material leaving the die should be within the allowed tolerance limits.

The results show that the less the stretching value is,the more the springback value will be.

The results show that the thicker the elastic cushion is,the more the springback value and increase of shape error will be.

The splitting strength, elastic modulus, shrinkage and engineering economy of them are also tested, then the mixing proportions are further optimized.

Abatract:For the big dimension of sand-gravel,the test method of elastic modulus in test methods of soils for highway engi-neering cann’t be applied to sand-gravel.

Research on resilient modulus of soft foundation dealt with blasting;

Stress-dependent characteristics and prediction model of the resilient modulus of subgrade soils;

Considerations on resilient modulus of earth foundation;

The test results show that the compression modulus,modulus of resilience,cohesion and angle of internal friction of the compaction loess increase with the compactive effort.

So this paper analyzes the current problems of design parameters of highway base and pavement and aiming at the different areas puts forward improving proposals concerning the modulus of resilience of earth subgrade and the material design parameters of the surface course and base course.

The gradation of the appointed limestone adopted the standard gradation,and the experiment of the confining compression strength,the modulus of resilience and the shrink deformation was made by using different cement quantity in the different ages in this paper.

Subgrade resilience modulus measuring by portable falling weight deflectometer(PFWD);

Through analyzing the relations between unloading ratio and resilience modulus, a proper engineering measure is taken,that will quaran.