Experimental Study On Mechanical Properties Of Lime-fly Ash Cement Stabilized Gravel Base

In China,the low-grade highways have long mileage with severe structural damage such as pavement cracking,subsidence.These highways often do not have other roads for the diversion of traffic,so the road maintenance can not interrupt the traffic for a long time.It is of important engineering significance to find a road maintenance material with lower cost and opening to traffic fastly.The source of gravel is abundant,and the price is low,the stabilized gravel after adding a certain amount of lime,fly ash,cement and other inorganic binding materials to the gravel is often used as the road base and subbase material.Due to the characteristics of fast hardening,significant early strength,short setting time,frost resistance,and wide environmental adaptability,sulfoaluminate cement is widely favored in rapid repair projects.In this paper,lime-fly ash-sulfoaluminate cement stabilized gravel and lime-fly ash-525 ordinary Portland cement stabilized gravel are selected which based on unconfined compressive strength test,split tensile strength test,freeze-thaw test,Studied the influence of different factors on the mechanical properties of stabilized gravel and discussed the feasibility of lime-fly ash-sulfoaluminate cement stabilized gravel as a rapid curing material for pavement base.Stabilized gravel samples with different mix ratios are placed in a standard curing box for 1 day,4 days,7 days,28 days,90 days,then unconfined compressive strength test and split tensile strength test are carried out.From the results of unconfined compressive strength test,it can be seen that the compressive strength first increases and then decreases with the increase of the inorganic binder content,the maximum strength is when the inorganic binder content(Lime,fly ash,cement)is 25%.The compressive strength gradually increases with the curing age or the increase of the cement content,and the initial growth rate is relatively fast;The strength of sulphoaluminate cement comprehensively stabilized gravel after curing for 1 day is much higher than that of 525 ordinary Portland cement comprehensively stabilized gravel,and there is no shrinkage in the later strength.Finally,the functional relationship between curing age,cement content and unconfined compressive strength is established.It can be seen from the split tensile strength test that the tensile strength is mainly provided by the cementation,which from the inorganic binder and between the binder and the aggregate,and the skeleton plays a small role;The strength increases with the increase of the cement content or the increase of the curing age;The splitting tensile strength of sulphoaluminate cement comprehensively stabilized gravel cured for 1 day is much higher than that of 525 ordinary Portland cement comprehensively stabilized gravel;Through the analysis of the test data,the functional relationship between the curing age,the cement content and the split tensile strength is established.The 28-day-cured gravel samples were subjected to 5 freeze-thaw cycles to explore the influence of cement content,cement type,and inorganic binder content on the frost resistance of stabilized gravel,it is obtained that the structure type of the mixture has the greatest influence on the frost resistance of the material,and the dense frame structure has the best frost resistance.