Cement Asphalt Mastic Constitutive Model And Microstructure Research

Cement asphalt mortar is a kind of organic-inorganic material composite ofcement, asphalt, mortar and additives; it is nowadays used in high-speed railwayballastless track and work for supporting, regulating and vibration reduction.Cement asphalt mastic is binder of cement and asphalt which is the key compositeto determine cement asphalt mortar mechanic properties. Meanwhile cement asphaltmastic is also widely used in road maintenance and semi-flexible pavementstructure. Paper aims at cement asphalt mastic dynamic mechanic properties,combined viscoelastic theory mastic constitutive equations were established, andinfluence factors of mastic mechanical performance was analyzed.Based on viscoelastic theory cement asphalt mastic constitutive equations wereestablished and DMA experiment method was put forward. Bsed on threeparameters solid model, generalized Kelvin model, three element fractionalderivative model and2S2P1D model cement asphalt mastic constitutive equationswere deduced, complex modulus was used to describe its dynamic mechanicproperties. DMA method was used to test cement-asphalt material dymamicmechanic properties and experiment conditions were determined.Based on analysis of CAM model effect of temperature and A/C on cementasphalt mastic dynamic mechanic properties was studied. Different A/C cementasphalt mastic viscoelastic parameters viriation with frequency was tested by DMAmethod at different temperatures, and according to Time-Temperature SuperpositionPrinciple master curves were obtained. Different A/C cement asphalt mastic20?complex modulus and phase angle master cureves were analyzed, combined withCAM model fit curve paramenters dynamic mechanic properties were compared.Accordiong to comparison it can be known CAM model parameters can accuratelydescribe mastic high, low temperature modulus and maximum phase angle value butcannot accurately describe mastic dynamic properties, and mastic dynamicproperties is obviously affected by A/C and temperature that shows character ofviscoelasticity.Based on dynamic properties analysis mastic constitutive models wereestablished and models feasibility were verified. Three parameters solid model, generalized Kelvin model, three element fractional derivative model and2S2P1Dmodel were adopted to fit cement asphalt mastic20?storage modulus mastercurves to confirm parameters value. Parameters of constitutive equations werecompared to analyze different A/C and temperatures effect on mastic dynamicmechanic properties. With comparison of different constitutive equationsparameters amount, accuracy of fitting, physical significance and applicability eachconstitutive model characters were confirmed.Based on mastic microstructure experiment results, mastic microstructuremodels were established, effect of microstructure on mechanic properties wasanalyzed and modulus prediction model was put forward. SEM, MIP and particlesize analysis experiment were conducted to test cement asphalt mastic apparentstructure, pore structure and cement product particle size. cement asphalt masticmicrostructure types,parameters and asphalt membrane thickness computationalmode were proposed based on test results. Different A/C mastic asphalt membranethicknesses were calculated and minimum network membrane thickness wasconfirmed. Combined with volume parameters and raw materials properties masticcomplex modulus was calculated.