Experimental Study On The Mechanical Properties Of Lime Fly Ash Cement Stabilized Macadam Base

Lime-fly ash-ordinary Portland cement stabilized macadam base has the characteristics of high strength and good stability in the later stage,and is one of the commonly used pavement base materials in China.However,its early strength is low,and it cannot be used as pavement maintenance material to open traffic quickly.Sulfur aluminate cement(SAC)has the characteristics of early strength,high strength,high impermeability,high frost resistance,corrosion resistance and low alkalinity,and has been successfully used in rapid road construction,road repair,cold construction and so on.Therefore,in this paper,lime-fly ash-sulfur aluminate cement stabilized macadam as the base material,and lime fly ash-common Portland cement stabilized macadam unconfined compressive strength(UCS),splitting tensile strength(STS)and antifreeze performance were compared and studied,to provide a reference for engineering.In this paper,firstly,the grading of crushed stones was determined within the recommended range of the specification according to Tabor theory,and the fractal dimension of crushed stones was calculated according to the fractal theory,and then the mixture ratio of lime,fly ash and cement stabilized crushed stones was determined.Finally,the mechanical properties of the materials were tested and analyzed,the main research contents included:(1)Determination of maximum dry density and optimum moisture content of limefly ash-cement stabilized macadam.The results of the compaction test show that the maximum dry density decreases and the optimal water content increases with the increase of the content inorganic binder.At the same dosage of inorganic binder,when the coarse aggregate content in gravel increases,the optimal moisture content of the mixture decreases,and the maximum dry density increases.(2)Will different mixture ratio and the gradation of lime sulphur aluminate cement stable macadam mixture of fly ash and lime-fly ash-ordinary Portland cement stabilized macadam mixture respectively maintenance 1 day,4 days,7 days,28 days,90 days,and then to different age on the unconfined compressive strength tests were carried out(UCT),discusses the curing age,the type of cement,cement,the content of inorganic binder,gravel mixture of UCS effect.Experimental results show that with the increase of curing age and the increase of the dosage of cement,UCS also along with the increase of mixture,lime fly ash has significant effects on the later strength of materials,sulphur aluminate cement on the early strength of mixture increase obviously,and no obvious decrease late UCS,can satisfy the requirement of the base materials UCS,achieve the goal of rapid opening traffic.(3)Different mixture ratio and the gradation of lime sulphur aluminate cement stable macadam mixture of fly ash and lime fly ash Portland cement stable macadam mixture,respectively maintenance 1 day,4 days,7 days,28 days,90 days,and samples of different age splitting tensile strength test(STT),discusses the curing time,the type of cement,cement content,inorganic binder content,cleavage strength grade macadam matching mixture(STS).The results show that sulfoaluminate cement can improve the STS in the early stage of lime-fly ash cement-stabilized macadam.With the increase of cement content and curing time,the STS in the mixture also increases.Lime fly ash plays an important role in the uplift of the STS in the later stage of the material.(4)Using orthogonal test method,the unconfined compressive strength loss(BDR)of lime-fly ash-cement stabilized macadam after curing for 28 days after five freeze-thaw cycles were taken as the index to investigate the effects of cement content,gravel grading,cement type and inorganic binder content on it.The experimental results show that the content of cement and inorganic binder are the main factors affecting the BDR of lime-fly ash-cement stabilized macadam.Relatively,the type of cement and the grade of macadam have little influence on the BDR.The antifreeze performance of sulfur aluminate cement stabilized macadam is better than that of ordinary Portland cement stabilized macadam.It can be seen that the early strength of lime-fly ash-sulfate aluminate cement stabilized macadam is higher than that of lime-fly ash-Portland cement stabilized macadam,and the late strength is not significantly reduced,and the freeze-thaw performance is good,so it is a good stabilizing material for road base.It can be used for the quick construction and maintenance of road,and can achieve the purpose of opening traffic earlier.