#05 - Pavement Management Program

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Prepared by: Bolton & Menk, Inc. Pavement Management Plan ǀ City of Lake Elmo Page 6 CRACK SEALING: Crack sealing prevents surface water from getting beneath the bituminous surfaces and into the aggregate base. Crack sealing is generally performed using hot rubberized crack sealing material. The procedure includes routing small cracks, cleaning and sealing. The city completes a crack sealing project each year with a priority on newer pavements and for any street that will be programed for seal coating in the same year. SEAL COATING (AND CRACK SEALING): Seal coating is a preventative maintenance activity which involves spraying an emulsified asphalt uniformly across the surface of existing pavement followed by the application of a uniform cover of crushed aggregate (trap rock). Seal coats do not provide structural support to existing pavement surfaces, nor will they repair pavement that has reached a point of structural failure. Crack sealing is performed in conjunction with any seal coat application. The primary reason to sealcoat a pavement is to protect the pavement from the deteriorating effects of sun and water. When an asphalt pavement is exposed to sun, wind and water, the asphalt hardens or oxidizes. This causes the pavement to become more brittle. As a result, the pavement will crack easier when exposed to traffic and temperature changes. Cracking allows water to migrate below the pavement and into the gravel base which in turn can form potholes or soft spots in the road, further deteriorating the pavement. A seal coat combats this situation by providing a waterproof membrane which not only slows down the oxidation process but also helps the pavement to shed water. A secondary benefit to seal coating is to increase then surface friction of the pavement. This is accomplished by the additional texture the cover of aggregate adds to the pavement. MILL AND OVERLAY: A bituminous overlay is a cost-effective method to renew the structural integrity and extend the life a street by grinding off a portion of the existing pavement surface and placing a new top layer of bituminous surfacing. Mill and overlays are generally conducted at 1-1/2” or 2” thickness. This method can be utilized on roadways where the existing underlying gravel base and subbase remain structurally sound. The new overlay surface will extend the useful life of the street but not to the same extent as a reclamation or reconstruction project, as the surface cracking for an overlay will likely be more extensive due to reflective cracking, and the overlay surface will quickly fail in areas where the aggregate base has diminished support. Mill and overlays are intended to provide a useful service life of 7 to 15 years. FULL DEPTH RECLAMATION (NO CURB AND GUTTER). A Full Depth Reclamation (FDR) is an engineered rehabilitation technique in which the full thickness of the bituminous surface and a portion of the underlying aggregate base is extracted, pulverized and blended to provide an upgraded, homogeneous base material, generally to an approximate 8-inch depth. A new bituminous surface is then paved over