Patent ID: 8303211

Claim:
A method for protecting highway subgrade in frozen soil areas, comprising: paving, on a subgrade, at least two pavement layers which have gradient thermal conductivity; arranging the at least two pavement layers in a descending order of thermal conductivity from top to bottom; wherein the pavement layers comprises a top layer, a medium layer and a bottom layer and thermal conductivity is layered among pavement layers, the top layer has the highest thermal conductivity, the bottom layer has the lowest thermal conductivity, and the thermal conductivity of the medium layer is between the thermal conductivity of the top layer and the thermal conductivity of the bottom layer; and wherein the arranging of the at least two pavement layers in a descending order of thermal conductivity from top to bottom comprises: adding micro nano powder having high thermal conductivity into the top layer; adding micro nano powder having low thermal conductivity into the bottom layer; and adding no micro nano powder into the medium layer, or adding micro nano powder having mid-value thermal conductivity into the medium layer or adding the micro nano powder having low thermal conductivity into the medium layer with the amount of the micro nano powder added into the medium layer being ½˜ 1/10 of the amount of the micro nano powder added into the bottom layer.