Durability Research On Cement Stabilized Macadam Through Micro-crack Technique

Cement stabilized macadam during early period of maintenance would crack because of contraction.The crack could incur reflective crack in the surface layer of the road.This thesis introduces a solution for the crack problem: micro-crack technique.The technique requires a vibratory roller to process the road during early period to create micro-cracks,thus reducing the shrinkage stress.The reduction could prolong the durability of the road by preventing widely long cracks.Researchers home and abroad have done a lot about the technique,the result is simple: a temporary loss of the mechanical strength in base material,while the loss could be reinstated through years.However,researches on the durability of micro-crack-processed base material are rare.To further study the problem,this thesis,through durability of both fatigue and freezing,and by experiments and computer analog,indicates the durability of micro-crack-processed cement stabilized macadam.The research shows no apparent influence to the base material.The procedure is as follows:1.After the introduction of the mechanism of the micro-crack technique,we analyze the factors that influences the technique.We dedicate the attenuation percentage as the indicator of different material strengths against press.Through experiments we acquire the relationship between the degree of micro-crack and the time of the vibration in some certain parameters,also the method of micro-crack degree controlling.2.We use low temperature simulator to simulate the actual temperature of the surface of the road.By experiments of freeze-thaw cycle,we record the anti-freezing coefficient and mass loss rate in differed micro-crack conditions.3.We make different samples of cement stabilized macadam in different conditions.The samples are tested in flexural tensile strength experiments,and the results are analyzed by Weibull.4.We build a CZM model by ABAQUS,which is used in the analysis of changes of stress during flexural tensile tests,thus indicating the mechanism of micro-crack technique's effect on cement stabilized macadam,hoping to bring reasonable suggestions to the reduction of adversity.The final test results show that the micro cracking of cement stabilized macadam base in a certain range will not affect its normal working life...