Performance Research On Diatomite Asphalt Mortar And Concrete

With the rapid development of the economy as well as the continuous progress ofscience and technology, the requirements on high temperature stability and low temperaturecrack resistance as well as temperature sensitivity of asphalt pavement material becomehigher and higher, which force us to make study on the basic performances which decideasphalt material strength.This paper focuses on asphalt and its mixture performance tests with10μm and35μmparticle size diatomites as the modifier. In order to study whether the technical performanceof the diatomite asphalt is the same to the matrix asphalt, and whether different-sizediatomites have the same effect on asphalt, some conventional indexes tests includingpenetration, softing point and ductility are done. And then, the apparent viscosity is testedas the high temperature performance evaluation indicator of asphalt mortar, while-15℃low temperature bending test using the homemade asphalt mortar beam specimen is donewith the bending strength R_Band the maximum bending tensile strain ε_Bfas well as thebending strain energy E as the indicators comprehensively analyzing the low temperatureperformances of asphalt mortar. For studying whether diatomite’ improvement effect onasphalt mixture is consistent with its performance in asphalt mortar, firstly, usingorthogonal test is used for determining the mixing ratio of diatomite, mine filler and asphaltand then, high temperature rutting test and low-temperature three-point bending test aredone to analyze diatomite asphalt mixture’s high and low temperature performance, endingup with the following main conclusions:1. Conventional indicators tests of diatomite asphalt mortar show that compared to35μm diatomite,10μm diatomite is easier to make asphalt stiff and its improvement effecton asphalt temperature sensitivity is stronger as well. By comparing softening point,equivalent softening point T₈00and equivalent brittle point T_1.2as well as5℃ductility ofasphalt mortar, it is known that10μm and35μm diatomite are both conducive to enhancingthe high and low temperature performance of asphalt, but10μm diatomite’s improvement effect is better;2. Brookfield Rotational viscosity test showed that, the apparent viscosity values of10μm and35μm diatomite asphalt mortar decrease with temperature increasing, butincrease with the content increasing. Under the same conditions, the apparent viscosity of10μm diatomite asphalt mortar is higher than35μm diatomite asphalt mortar, indicatingthat10μm diatomite has better effect on improving asphalt’s temperature performance. UseSaal test formula to analyze the viscosity-temperature relationship of diatomite asphaltmortar, and results show that the order of temperature sensitivity coefficient m is m_{10μmdiatomite asphalt mortar}<m_{35μm diatomite asphalt mortar}<m_{matrix asphalt}, further verifing10μm diatomite ismore conducive to weakening asphalt temperature sensitivity. In addition, theviscosity-temperature curve infers the calculated mixing and compaction temperatures of10μm diatomite asphalt mixture are higher than35μm diatomite asphalt mixture;3.-15℃beam bending test of diatomite asphalt mortar indicates that, the results ofusing R_Band ε_Bto characterize the low temperature performance10μm and35μmdiatomite asphalt mortar are not consistent. But according to the definition of the bendingstrain energy E,10μm diatomite asphalt mortar has the best low temperature performance,followed by35μm diatomite asphalt mortar, with matrix asphalt last. Range analysis oforthogonal test shows that diatomite content affects the level of the high and lowtemperature performance of the asphalt mortar more than diatomite particle size;4. According to orthogonal test,16specimens are arranged to determine the bestmixing combination that evaluates high-temperature asphalt viscosity:15%diatomitecontent:100%mine filler:100%matrix asphalt content; while the best mixing combinationthat evaluates low temperature cracking performance:15%diatomite content:90%minefiller:100%matrix asphalt content;5. The asphalt mixture rutting test indicates that both dynamic stability indicator andrutting permanent deformation indicator show10μm diatomite asphalt mixture has the besthigh temperature performance, followed by35μm diatomite asphalt mixture, with matrixasphalt mixture last. The test conclusions are consistent with diatomite’s improvementeffect on high temperature performance of asphalt mortar, further validating asphaltmortar’s important influence on the high temperature performance of the overall asphalt mixture.6.-15℃three-point bending test of asphalt mixture indicates that the order of R_Bandε_Bas well as E are the same, which is10μm diatomite asphalt mixture the largers, followedby35μm diatomite asphalt mixture, with matrix asphalt mixture smallest. Although themaximum bending tensile strain ε_Bresult of diatomite asphalt mortar is not the same todiatomite asphalt mixture, their comprehensive performance test results are consistent,further validating diatomite has better improving effect on the low temperatureperformance of both asphalt and asphalt mixture.