Like many municipalities, North Ogden, Utah had stopped using chip sealing as a preventative maintenance tool on their city streets. Reasons that the process was discontinued included cover aggregates or chips, as they are referred to, peeling off streets and ending up in gutters, rough surface texture on residential streets and resident complaints. That changed in 2012 when the Public Works Director, Mel Blanchard, discovered how ESCS (expanded shale, clay and slate) lightweight cover aggregate could prevent these problems from happening.
Surface treatments are called by different names depending on the local area. Chip seal (or seal coating or bituminous surface treatment) is constructed by spraying a asphalt emulsion or hot liquid asphalt onto the road surface, then covering it with an aggregate, and using pneumatic rubber-tire rollers to embed the aggregate into the asphalt. When ESCS lightweight aggregate is bonded to asphalt, it creates an advanced road surface that is safer, more economical and longer lasting than those created with traditional natural sands, stone and gravels.
Because of the increased surface area from micro-pores and the absence of fine dust, ESCS lightweight aggregates have a superior bond with asphalt emulsions and generally do not peel off pavements. Additionally, ESCS lightweight aggregates do not break windshields, which has been a concern in many areas. ESCS lightweight aggregates are usually darker in color and appear more like asphalt pavement than typical normal weight cover aggregates, even without fog coating.
Safety is also increased because ESCS lightweight aggregate road surfaces provide superior skid resistance, wet or dry. The high skid resistance is maintained throughout the road’s service life because of ESCS lightweight aggregate’s rough micro surface texture. Pavement made with natural aggregates can polish or become slick under the wearing action of traffic, and lose a large percentage of their skid resistance. Due to the internal void structure found in ESCS lightweight aggregates, they do not polish as they wear. The pavement maintains its high skid resistance because as it wears, fresh interior cells with rough ceramic edges are continually exposed.
The city of North Ogden has consistently used ESCS lightweight aggregate chips since 2012, to seal and prolong the life of their streets with great success. In fact, during their 2016 project, the Mayor of North Ogden City, Brent Taylor, produced a video to educate the public on the importance of chip seal as a preventative maintenance tool, as well as the benefits of ESCS lightweight aggregates. The video can be viewed at www.youtube.com/watch?v=3gtxP2yK5Ug. Visit the asphalt chip seal section of the ESCSI website for more information on the benefits of ESCS lightweight aggregates in road maintenance applications or contact your local ESCS supplier.