Study On The Influence Of Loads During Constryction And Curing Period On The Damage To Cement-stabilized Macadam Base

At present, there are no strict regulations on the load of the construction period and the effect of the construction vehicle load on the pavement stru cture design is not considered in domestic norms. In addition, in the construction process of semi rigid base asphalt pavement construction process, limited by season and time, it is relatively common to see the phenomenon of catching the rush deadlines. During the construction, superstructure is generally paved after 7days or in a shorter time( not reaching 90 or 180 days), vehicles, transport vehicles, paving machine, roller and other construction equipment will inevitably make damage to the lower bearing layer of unformed enough strength and stiffness. During the construction period, it produces the internal damage of pavement structure, and produces micro cracks in cement stabilized macadam base structure. So it lead s to hidden trouble for early damage. Although at the beginning of the road to traffic, the micro cracks in the basic level will not affect the road performance. However, with the repeated action of traffic load, the strength of the base structure will decline sharply, crack propagation, and serious influence the road performance and service life. From the construction of the old road transformation, we can see that the serious damage of construction vehicle load on the pavement, so the new road construction load and non load factors, such as curing time, temperature, may produce congenital damage to the road, and the road may produce different degrees of damage after the quick operation.In this study, through the statistics of construction of vehicle load, using the theoretical analysis and experimental method, the author analyzed the cement stabilized gravel structure damageFirstly, the author adopted different curing temperature, different instars of health of cement stabilized macadam in order to imitate the weather conditions that may encounter in the construction process. And then he carried on the unconfined compressive strength, splitting strength and compressive resilient modulus test. The results showed that the low temperature has great influence on cement stabilized material strength and modulus. The strength and modulus of the materials are in a low level in the low temperature, especially in the period of low temperature and low age, the indexes of the material is very low.Secondly, bases on vehicle load action of the construction period, the author adopted the ABAQUS finite element software, which is based on the experimental data, and calculated the cement stabilized macadam bottom layer of the primary tensile stress at the bottom, then put forward the curing time and allowed loa d scope that the bottom base does not have the ultimate destruction during the construction.Finally, the author conducted the bending tensile strength test in different curing temperature and curing time. On the basis, he did bending tensile fatigue test in different temperature of early age and established the fatigue prediction model of early age indoors. Miner linear damage theory is used to analyze the damage of the subbase course at different working conditions of construction. The result showed that the damage of the subbase is the most under direct load action, that is the most serious damage to the subbase. Through the analysis, it can be concluded that the damage of the subbase can be reduced by increasing the strength of the base material and increasing the age of the curing.