Bleeding or flushing asphalt appears shiny, glossy or glass-like, as opposed to dull black. Bleeding and flushing are two terms often used interchangeably but they are unique in a couple of fundamental ways. While bleeding asphalt requires immediate maintenance, flushing asphalt may not.
What Is Bleeding Asphalt?
Bleeding asphalt is defined as the upward movement of asphalt in a seal coat or surface treatment that creates a film of asphalt on the surface of roadways. The cause relates to excess asphalt binder filling empty space in the aggregate mat, this material moves upward to the surface of the asphalt. Then, under the pressure of heat and traffic, it creates a non-reversible problem that worsens over time.
When traffic drives over bleeding pavement it creates a smacking sound, similar to the sound made by tires driving over wet pavement. Bleeding is most common during seal coat or surface treatments when the binder has not yet fully cured.
Is Bleeding Pavement A Big Deal?
Bleeding pavement leads to a couple of issues if left unresolved. For one, bleeding asphalt will stick to tires and cause tracking. Over time the seal coat or surface treatment aggregate will start to separate from the asphalt, leading to entire chunks of pavement peeling away. Bleeding pavement should be fixed as soon as possible. The quicker you conduct repairs the less likely it is that fresh seal coat or surface treatment will lift off the pavement.
What Causes Bleeding Asphalt?
-Binder issues, too much or the wrong type of binder.
-Weather issues, such as temperature or high humidity levels.
-High levels of consistent traffic volume.
What Is Flushing Asphalt?
Flushing asphalt is similar to bleeding asphalt in that it involves excess asphalt binder building up on the surface layer of pavement. There are a few defining differences between bleeding and flushing asphalt.
For one, flushed pavement is not always the urgent maintenance problem that bleeding is. Flushed pavement incurs a similar process in which asphalt fills the voids in the aggregate mat, but when the binder comes to the surface it is not liquid, instead it is solid or semi-solid. That means flushed pavement still maintains its seal coat.
Flushing can occur even after asphalt goes through the proper curring process, while bleeding is more likely to occur when the binder remains tender. Flushed pavements have usually already survived through one full year. Even properly constructed seal coat commonly undergo progressive flushing as the aggregate naturally wears down over time.
How To Identify Flushed Asphalt
Flushed pavement may appear darker or discolored during moderate stages of flushing. As flushing increases the surface may lose texture or appear glossy and shiny. High severity flushing will begin to show tire marks in the asphalt when the weather is warm.
Over time, flushed pavements may begin to track and bubble, resulting in bleeding asphalt. At this point, it’s common to notice excess asphalt building up along the wheelpaths.
Is Flushing Asphalt A Big Deal?
While in some cases flushing requires no maintenance or overall concern, it can present some issues over time. If necessary maintenance is overlooked the pavement will become slick and provide low skid resistance. Wet weather conditions create very slippery roadways. The most severe cases transpire when flushing occurs alongside rutting and water accumulation in the wheelpaths.
What Causes Bleeding & Flushed Pavements?
Aggregate Issues: If the seal coat or surface treatment becomes void of its rock content, bleeding or flushing will result. Loss of rock content, too much rock, use of overly soft rock or dirty rock and modified aggregate grades are all examples of aggregate issues.
Binder Issues: Binder issues such as binder selection, binder application rate, binder curing, binder quality and notoriously problematic binders can lead to bleeding and flushing.
Traffic Issues: Heavy volumes of traffic, consistent traffic from heavy trucks and stop and go traffic, commonly related to intersections, are all types of traffic that contribute to a greater risk.
Weather & Environment: High temperatures, low temperatures, fluctuating temperatures and humidity play a big role in the development of flushing and bleeding.
Faulty Construction: The most common contributing factor to flushing and bleeding is poor construction. Good design and proper application practices can prevent a lot of issues from the get-go. In order to help prevent bleeding and flushing pavements, proper assessment of existing pavement conditions are adamant. Also, it’s important to apply a quality seal coat, treat any issues regarding rutting in wheelpaths, take care of any special curing needs and use fog seals to offset rock loss.
How To Treat & Prevent Flushing & Bleeding Asphalt
The experts at Kleenco Construction know exactly how to treat and repair flushed and bleeding pavements. We are also skilled at constructing asphalt that is far less likely to incur preventable damages in the first place, all thanks to high quality materials and proper construction practices.