Deterioration Laws Of Semi-rigid Base Modulus

Because of its great bearing capacity, well water stabilization and low manufacturing cost, the semi-rigid base material has been used for highway base widespread. When traffic loads on semi-rigid base, its strength deteriorates and modulus reduces. So it is necessary to do research on deterioration laws of semi-rigid materials modulus.Firstly, this paper has summarized deterioration laws of various materials modulus domestic and foreign. Following the fatigue performance and modulus deterioration laws of three common semi-rigid base materials have been studied. Based on having indoor fatigue test on semi-rigid cement stabilized crushed stone (suspend-dense structure and framework-dense structure), semi-rigid cement stabilized fine-textured soil with homogeneous-dense structure and lime and fly-ash stabilized crushed stone with suspend-dense structure, the author has collected strain variation at the bottom of samples during fatigue loading. The paper has analyzed tension strain at the bottom of samples and presented the calculation method as well as value of limit tension strain. Through comparison analysis, the author has found that tension train develops in three stages. Strain growth rate is different in each stage. The proportion each stage accounting for total fatigue life only has relation with material itself but is independent of stress level.In this paper, deterioration laws of each material modulus under fatigue loading also have been analyzed. Modulus deterioration also has three stages. In the first stage, cement (fly-ash) stabilized crushed stone (gravel) modulus deteriorate to 60% of original modulus approximately accounting for 15%～20% of total fatigue life. In the second stage, modulus deteriorates more slowly and has linear relationship with loading number. It accounts for about 60%～75 %. Deterioration range varies with stress level. The third stage is destabilization damage accounting for 10%～20% of fatigue life. During this stage, modulus reduces rapidly. Deterioration rate differs from stress level. The higher the stress level is, the greater the deterioration rate is. At the same time, effective modulus of has been determined. At last, the author has made comparison research with other materials.