| Lime-fly ash crushed stone was widely used in highway pavement in China because of its good mechanical and road performance.The early constructed these roads have entered a period of large and medium-sized repair,resulting in a large number of recycled Lime-fly ash base materials（RLBM）.On the basis of the existing research results,the material composition and physical properties were analyzed and studied by various modern materials analysis methods.These methods include:X-ray diffraction test（XRD）,scanning electron microscopy（SEM）,and Fourier transform infrared spectroscopy（FTIR）.In order to verify whether the RLBM was active,the cement mortar test of the RLABM with particle size less than 0.075mm was carried out.Then according to the requirements of subbase and base of secondary and secondary below roads,the mix proportion design of 100%and 70%two kinds of RLBM mixture ratio were carried out respectively.At the same time,the mechanism of RLBM was explored by using XRD.The dry shrinkage of RLBM base and sbbase were emphatically studied,and the improvement measures were put forward.In addition,the temperature shrinkage characteristics,fatigue resistance and frost resistance were discussed.The results are as follows:（1）Calcite were produced during the reuse of RLBM by cement and lime.The increase of calcite content leaded to the increase of unconfined compressive strength of recycled old two ash macadam.The height and area of the main peak of calcite can be used to determine the unconfined compressive strength of RLBM.The greater the height and the area of the main peak,the greater the unconfined compressive strength.（2）The change law of water loss rate with dry shrinkage test time was natural logarithmic type.In the beginning of the test,the water lost mainly for free water,the dry shrinkage strain produced the smallest contribution.Then,the main form of lost water was adsorbed water,and the contribution of adsorbed water to the shrinkage strain was approximately linear.Finally,when the water loss rate reached more than 90%of the water content,the bound water begined to lose,and the contribution of the bound water to the dry shrinkage strain was greater than that of the adsorbed water.（3）The dry shrinkage strain of 4%cement stabilized RLABM base layer was 275×10-6,an increase of 43%compared with cement stabilized virgin aggregate,dry shrinkage slightly attenuated.4%dry shrinkage strain of cement stabilized RLABM subbase was 452×10-6,which was 135%higher than cement stabilized virgin aggregate,and dry shrinkage property had obvious attenuation.Under the same condition,the lime stabilized RLABM dry shrinkage was 567.5×10-6 and 997.1×10-6for base and subbase respectively,difficult to meet base or subbase on dry shrinkage performance requirements after regeneration.（4）The dry shrinkage strain of wet curing 14days was 19%lower than that of wet curing 7 days,the dry shrinkage strain of wet curing21 was 25%lower than that of the 7 day,and the dry shrinkage strain of wet curing 28 days was 37%lower than that of wet curing 7 days.With the increase of wet curing time,the reduction effect of dry shrinkage strain becomes worse. |
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