Study On Mixture Ratio Design And Road Performance Of Cement Stabilized Gravel Base Of Fracture Resistant Highway

The cement stabilized macadam base layer is a semi-rigid base layer.Due to its good overall performance,strong bearing capacity and economical application,it is widely used in domestic highway construction.However,due to the effects of temperature shrinkage and shrinkage,cement stabilized macadam is prone to generate a large number of shrinkage cracks,and extends to the asphalt surface layer to form reflective cracks,which seriously affects the road performance and service life of the road.Therefore,this paper focuses on the problem of easy cracking of cement stabilized macadam base layer by optimizing mix design,strengthening indoor laboratory control and improving construction process;the combination of customs clearance indoor test and engineering actual paving test section.The mix design and road performance of the anti-cracked cement stabilized macadam base mixture were developed.In the optimization of mix design,through the analysis of the structural composition and grading design of cement stabilized macadam materials,the gradation design of the coarse and fine aggregates was carried out separately,and then the 7d no side of the mass ratio of different aggregates was determined by computer.The compressive strength value is limited,and the synthetic gradation of the mixture is finally determined,and verified by the Beray method to finally determine the anticracking gradation of the mixture.Finally,on the basis of the determined gradation,the cement dosage was determined to be 4% by experiment.In order to determine the crack resistance and road performance of the designed grading,the design grading and the specification median level were respectively formulated into corresponding test pieces.Comparative analysis of the performance of the two grades of mechanical properties and road performance.The test shows that the unconfined compressive value,compressive rebound modulus and frost resistance of the design gradation are 13.9%,8.6%,and 2.3% higher than the average of the normative median gradation respectively;dry shrinkage strain and dryness The shrinkage coefficient,average temperature shrinkage coefficient,and cumulative scouring mass loss were 16.4%,17.7%,14.2%,and 35.1%,respectively.Tests have shown that the design gradation has good crack resistance.In terms of laboratory control,the surface vibratory compactor is mainly used to replace the heavy-duty compactor.Comparative analysis by vibration method,heavy-duty compaction method and static pressure forming test piece showed that the maximum dry density average determined by vibration method was 1.036 times determined by heavy-duty compaction method,and the optimum moisture content was 0.924 times.The 7d unconfined compressive strength of the specimens formed by the vibration method is much higher than that of the hydroformed specimens.The influence on the grading,the dry shrinkage strain and the dry shrinkage coefficient are much smaller than those of the hydroformed specimens.The surface vibration compaction method can effectively improve the crack resistance of the cement stabilized macadam mixture.In terms of construction technology,combined with Changjiu high-speed reconstruction and expansion project,the traditional static stirring technology was replaced by vibration mixing technology in mixing warfare.Related research shows that the vibration mixing technology can shatter the water and cement mass and ash group in the cement stabilized macadam,so that it is evenly distributed in the mixture,wrapped in the aggregate,and the quality of the cement stabilized material is mixed.Stable and improved durability;the uniformity of the mixed mixture is good,which stimulates the performance of the material itself,thereby reducing the cement dosage,saving cement,creating additional economic benefits for the use unit;not separating from transportation and paving works,construction The performance is good,the core of the mixture is easy to be taken,the compactness is good,and the cracks in the base layer of the road surface are greatly reduced.