Generally, a bituminous patch repair work or surface treatment (BST), also known as a seal coat or chip seal, which is a thin protective wearing surface that is applied to a pavement or base course. It can provide all of the following:
a) A waterproof layer to protect the underlying pavement.
b) Increased skid resistance.
c) A filler for existing cracks or raveled surfaces.
d) An anti-glare surface during wet weather and an increased reflective surface for night driving.
A bituminous patch repair work contains the following steps:
1. Surface preparation:- Surface defects, such as potholes, are repaired and the existing surface is cleaned (e.g., by a street sweeper).
2. Asphalt material application:- Typically, an asphalt emulsion is applied from a spray truck to the surface of the existing pavement.
3. Aggregate application:- A thin aggregate cover (only one stone thick) is spread over the asphalt material before it has set. The aggregate usually has a uniform gradation.
4. Aggregate embedding:- A roller (usually a pneumatic tire roller) is used to push the aggregate into the asphalt material and seat it firmly against the underlying pavement. Generally, about 50 percent of each aggregate particle should be embedded in the asphalt material after final rolling. About 70 percent of each aggregate particle will be embedded after several weeks of traffic. It is common to place an aggregate “chokestone” on top of the uniformly graded larger aggregates after embedment. Chokestone is essentially a finer aggregate gradation (e.g., less than 12.5 mm (1/2 inch)) used to make a more dense aggregate matrix at the level of embedment. This more dense matrix helps prevent excessive aggregate loss due to traffic.