Oct. 19, 2020
Foamed asphalt cold recycling technology is the recycling of recycled asphalt
pavement materials and cement stabilized base materials. It can not only give
full play to the "surplus value" of the old asphalt mixture, promote the
recycling of old pavement materials, protect the ecological environment, and
reduce resource waste, but also convert the semi-rigid pavement structure to a
semi-flexible structure, which extends the use of road asphalt life.
What is foamed asphalt?
Foamed bitumen is also called expanded bitumen, in which a certain amount of room temperature water is injected into hot bitumen to expand and form a large amount of bitumen foam. After a short period of time, the bitumen foam bursts. When the foamed asphalt is in contact with the aggregate, the asphalt foam is interspersed into tens of thousands of "small particles", which are scattered on the surface of the fine aggregate to form a fine joint filler with a large amount of asphalt. After mixing and compacting, these fine particles The material can fill the gap between the coarse materials and form a mortar-like effect to stabilize the mixture.
Foamed asphalt cold recycled mixture can be used as the lower layer and base layer of asphalt, and shows good performance. Its advantages are mainly reflected in the full-thickness regeneration of asphalt surface and base materials, and the conversion of semi-rigid base to semi-flexible base, which is in line with the international trend of flexible pavement bases; foamed asphalt regeneration technology only requires heating of the asphalt, no heating And drying aggregates. This saves energy; compared with the semi-rigid base, its maintenance time is short, the construction period is short, and the impact on traffic is small.
Practical performance of foamed asphalt
At present, the expansion rate and half-life are mainly used to evaluate the foaming characteristics of asphalt. Expansion rate refers to the ratio of the maximum volume reached when the asphalt is foamed and expanded to the volume when the foam completely disappears, reflecting the viscosity of the foamed asphalt. Half-life refers to the time required for foamed asphalt to drop from the maximum volume to half of the maximum volume, calculated in s, reflecting the stability of foamed asphalt. When evaluating the foaming effect of asphalt, the expansion rate and the half-life are two inseparable indicators. The best foaming effect should make both values relatively large, and cannot be controlled by a single indicator. It is recommended that the expansion rate of foamed asphalt is ≥10 times and the half-life is ≥8s.