Study On Application Of Vermiculite In The Thermal Resistance Pavement

Although asphalt pavement has been widely applied, its various diseases cause obstacles for management and road transportation. Rutting is one of the most damaging diseases, which not only affects the driving comfort, security, but also shorten the service life of pavement.Research shows that the rutting is mainly produced in middle surface layer, then in the first surface layer and the base surface layer. High temperature is cause rutting directly. Therefore, thermal resistance pavement arises at the historic moment, which controls rutting by reducing the pavement temperature. This study will apply the heat preservation material-vermiculite for asphalt pavement in different forms to reduce pavement temperature and slow down the occurrence of the rutting.Firstly, vermiculite is used as fine aggregate mixed with asphalt concrete, which is used as the first surface layer. As thermal resistance surface layer, the vermiculite asphalt concrete reduces internal and surface temperature in the first surface layer. Therefore, this study use vermiculite replacing the fine aggregate of SMA-13 and AC-13 respectively according to certain proportion, then test the surface and bottom temperature of vermiculite asphalt mixture specimen. The result shows that, SMA-13 with vermiculite content of 50% and 100% can reduce 3.5℃ and 6.0℃. The cooling effect of AC-13 with vermiculite content of 75% is more than 6℃. But road performance tests find that vermiculite mixed with the SMA-13 and AC-13 has a different degree of damage. Finally draw the conclusion: adding vermiculite AC-13 cannot be used for asphalt pavement, and SMA-13 with vermiculite content of about 50% can be used for the thermal resistance asphalt pavement surface.Secondly, vermiculite asphalt concrete is used to replace ordinary glue layer, laying between the first surface layer and the middle surface layer as thermal resistance layer in order to reduce the temperature of the middle surface layer. This research adopts the vermiculite asphalt concrete paving between two specimens with layer spread method and make double specimen. Testing double specimen surface temperature and bottom temperature learned that when the thickness of vermiculite thermal resistance is 3 and 5mm, it can reduce the temperature of 2.8℃ and 4.5℃ respectively, at the same time vermiculite thermal resistance is verified seal cooling effect using the infrared thermal imager. Detection of double specimen interlaminar shear strength finds that the bigger the thickness of vermiculite thermal resistance sealing layer is, the worse shearing strength between layers becomes. In order to ensure the good bonding between the layers, this article suggested that the thickness of vermiculite thermal resistance sealing layer should be 3mm and should be single.Finally, this study analyses the economic benefit of vermiculite thermal resistance pavement. SMA mixture of 13-50% vermiculite basiclly don’t change the cost of materials and the cost of 3mm vermiculite thermal resistance seal material is 1.5 times higher than normal glued layer.