Research On Diatomite Modified Asphalt In Permafrost Region

The permafrost regions on Tibetan Plateau have many characteristics, such as cold weather, great temperature difference between day and night, annual average temperature is low, frequent freeze-thaw cycle, solar radiation is strong. The application environment of asphalt pavement built in permafrost regions is so harsh, that the early damage of low-temperature cracking, deformation, loose, pit slot easily occur, seriously reduce the use quality and service level of the road, the requirement of asphalt pavement is not satisfied with common asphalt mixture.This article takes diatomite as asphalt modifier, studies the pavement performance of diatomite mucilage of modified asphalt by general indicators tests and DSR,BBR tests; it also studies the low-temperature crack resistance of diatomite modified asphalt mixture, and the influence of aging towards low-temperature crack resistance by cold bending rupture test; then it gives research on mixture's water stability through marshall immersion test and freeze-thaw splitting test, and at last on mixture's thermal insulation performance through indoor environment of solar radiation source simulation method,simulated the temperature field of general asphalt pavement and diatomite modified asphalt pavement.The results show that, diatomite particle is loose and porous, has large surface area, and its strong oil absorption is able to make asphalt become sticky; asphalt combining with diatomite increases the adhesion between mucilage and aggregates, and asphalt film thickness, then it possesses good retractility and recoverability under external load, and its low-temperature crack resistance also can be improved; diatomite disperses among the mixture void evenly, therefore, the porosity is decreased and the water stability is increased; the thermal conductivity of diatomite asphalt mixture which has excellent thermal insulting properties is only 1/2~1/3 of common asphalt mixture.The excellent performance of diatomite modified asphalt mixture is so suitable for using in permafrost regions, that the distresses of asphalt concrete surface such as low-temperature crack, loose, pit slot and so on can be significantly prevented; diatomite modified asphalt mixture has better thermal insulation properties, which could effectively prevent external heat from entering frozen layer below subgrade through surface layer, so that the frozen layer in the range of subgrade can be positively protected.