Agenda Packets - 1991/07/01 - Laserfiche WebLink

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also the method for repairing severe cracking distress called 'alligator' cracking. Sealing cracks in pavements is another method of keeping moisture out of the pavement system. This consists of applying an asphalt material, usually modified by adding some form of rubber, to the cracks after they are cleaned of sand and other materials. • Pavements deteriorate on a continually accelerating schedule. A pavement at 10 years is often 90% of the quality of a new pavement. At 15 years the quality is maybe 80%; and 50-60% at 20 • years . Left unchecked few pavements are functional after 25-30 years. Preventive maintenance is an attempt to alter the aging process of pavements. National research has shown that $1 .00 spent on preventive maintenance while a pavement still retains much of its original quality will restore the pavement system to a higher level and significantly slow the aging process. Quite often the research shows that the expenditure of $1 . 00 on preventive maintenance will save more that $5 . 00 on rehabilitation or reconstruction. Reconstruction/Rehabilitation Pavements that have deteriorated beyond a certain point can not • effectively be helped by preventive maintenance strategies. A chip seal may add a year or 2 of life, but long term improvement necessitates a more intense alternative . Reconstruction is required for pavements in very poor condition: Rehabilitation may be an alternative for marginal pavements. The computer program indicated that 7. 25 miles of streets were beyond preventive maintenance. The traditional answer would be reconstruction of these streets. In some cases this is required for utility work, storm sewer upgrades, or for correcting deep seated deficiencies. • In many cases an alternative is to rehabilitate the pavement. This may consist of a structural overlay of 3 or more inches of asphalt where grades allow or some method of pavement surface removal and new pavement construction. Ramsey County has been using a cold recycling process that grinds the existing pavement, - - reet incorpora • •' . ' . pavemen in e base course, and then pacing a new asphalt surface onthestreet. Another method occasionally utilized is a system of heating pavement surfaces until they are workable , scarifying the surface, and then adding additional asphalt material prior to compacting the surface. The appropriate strategy requires a detailed review of the conditions peculiar to each pavement . section. However, it a majority of cases one of the rehabilitation alternative is likely to be appropriate . By carefully choosing the appropriate alternative, it is estimated that the average cost of a • reconstruction/ rehabilitation program can be reduced to $25 to 3 da