In rainy and humid areas, the porosity of the asphalt surface of expressway and the first-class highway is large, which may cause serious water seepage, or when the paving base cannot pave the asphalt surface in time and vehicles need to pass, it is advisable to spray the oil layer before paving the lower seal coat.
The difference between seal coat and primer: the purpose of the lower seal coat is to seal the surface, and it is not necessary to penetrate it; Permeable oil needs to penetrate to a certain depth. At the same time, its function and purpose are quite different. At present, in some projects, aggregate and sand are sprinkled on the priming oil as the lower sealing layer because it can't penetrate the semi-rigid base, so it may play a sealing role, but it can't replace the priming oil.
Slurry seal coat is generally used for the preventive maintenance of secondary and below roads, and is also suitable for the lower seal coat of new roads.
The lower sealing layer is a structural layer set on the surface of semi-rigid base, which aims to protect the base from being damaged by construction vehicles, which is beneficial to the health of semi-rigid materials, and also prevents rainwater from infiltrating into the structural layer below the base and strengthens the combination between the surface layer and the base. Although there are many methods to make the lower seal coat, practice has proved that asphalt single-layer pavement is one of the economical and effective methods.
Functions and applicable conditions of the three:
Function and application conditions of permeable layer
The function of the prime coat is to make the asphalt surface layer and non-asphalt base layer combine well, and spray emulsified asphalt, coal asphalt or liquid asphalt on the base layer to form a thin layer on the surface of the base layer.
In the following cases, prime asphalt shall be poured:
① Graded macadam and graded macadam base of asphalt pavement.
② Cement, lime, fly ash and other inorganic binders stabilize the soil.
(3) Granular semi-rigid base must be sprayed with prime asphalt.
Function and application conditions of adhesive layer
Function of adhesive layer: a thin layer of asphalt material paved to strengthen the adhesion between asphalt layers and between asphalt layers and cement concrete pavement.
When the following conditions are met, sticky asphalt shall be sprinkled:
(1) before paving the upper layer, the asphalt layer under the double-layer or three-layer hot-mix asphalt mixture pavement has been polluted.
(2) Laying an asphalt layer on the old asphalt pavement layer.
(3) Paving asphalt pavement on cement concrete pavement.
④ Sides of kerbs, rainwater inlets, inspection wells, etc. Contact with the newly laid asphalt mixture.
Function and application conditions of seal coat
The function of the seal coat is to close the surface cracks and prevent moisture from infiltrating into the thin asphalt mixture layer laid on the surface or base.
What is spread on the surface of the surface layer is called the upper seal layer, and what is spread under the surface layer is called the lower seal layer.
In case of any of the following circumstances, a seal coat shall be paved on the asphalt surface:
(1) Asphalt pavement has a large gap and serious water seepage.
② Cracked or repaired old asphalt pavement.
(3) Old asphalt pavement that needs to be paved with wear layer to improve the anti-skid performance.
(4) New asphalt pavement that needs to be paved with wear layer or protective layer.
The function of slurry seal coat: it is an asphalt seal coat made of properly graded stone chips or sand and fillers (cement, lime, fly ash, stone powder, etc.). ), emulsified asphalt, additives and water are mixed in a certain proportion and evenly spread on the road surface.
Under the following circumstances, the lower seal coat shall be laid below the asphalt surface:
① Located in the rainy area, the asphalt surface has a large gap and serious water seepage.
(2) After the base course is paved, the asphalt surface can't be paved in time, so the traffic must be opened.