Study On Construction Technology Of Cement-stabilized Macadam Base In Low Temperature Environment

Due to the influence of climate in northern China,many highway construction projects still need to carry out the basic course construction in the low temperature environment in late autumn or early winter.However,cement stabilized macadam is a temperature-sensitive material.The hydration process of cement is slow at low temperature,which seriously affects its early strength,modulus and other properties.In order to meet the engineering requirements,it often prolongs the health age and ensures the strength requirement.In order to shorten the construction period and ensure the engineering quality in the environment of low temperature at the end of autumn or the beginning of winter,in this paper,based on the actual project,the influence of temperature,early strength agent and cement dosage on the properties of cement stabilized macadam is studied on the basis of analyzing the temperature variation law of cement stabilized macadam base under low temperature environment.Furthermore,the construction scheme of base course based on early strength cement stabilized macadam is put forward.The specific contents of the study are as follows:(1)Research on the determination method of indoor test curing temperatureTemperature is an important factor affecting the strength growth of cement stabilized macadam.In actual projects,the temperature of cement stabilized macadam base varies with atmospheric temperature,weather conditions,measured time,cement stabilized macadam mixture ratio,maintenance conditions and other factors.In order to fully simulate the outdoor temperature change,the indoor test curing temperature was determined by comparing the measured temperature change law of the pavement base with the internal temperature change law of the specimen under different curing temperatures.(2)Study on the change of Mechanical Properties of cement stabilized Macadam Base under low temperature EnvironmentThrough laboratory test of cement stabilized crushed stone strength under simulated low temperature environment,the unconfined compressive strength of cement stabilized macadam with different factors is analyzed.The influence of compressive resilience modulus,splitting strength and the change of strength of cement stabilized macadam base during freeze-thaw cycle are discussed.The important measures to improve the early strength of base course under low temperature environment are put forward.(3)Study on mix dcesign of cement stabilized macadam base material with early strength agentBy analyzing the influence of the early strength principle of additives and the amount of additives on the performance of skeleton dense graded cement stabilized macadam.Based on comprehensive experience,theoretical calculation and fatigue test,the dense gradation range of skeleton,cement dosage and early strength agent dosage suitable for low temperature environment are recommended,and then the design method of cement stabilized macadam base material composition with high strength characteristics and good durability at low temperature is proposed.(4)The control of vehicle axle load and health age based on different spreading construction schemesKen Pave’s mechanical analysis software was used to analyze the damage of cement stabilized macadam structure layer.The required curing time and allowable load range for the subbase during the construction period were proposed,and the technical measures to reduce the damage of construction load to the subbase were proposed by adopting a continuous paving scheme and increasing the curing age.