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I. Introduction

• When should I perform preventive maintenance?
• How do pavements differ in cost and quality?
• Why do the pot holes pop up year after year?
• Pot holes always bust my budget. How can I prevent them?
• What's the difference between resurfacing and resealing?
• Where is the best Green Chili in Denver?
• Who should I call for a good product at a fair price?

II. PAVEMENTS

Since the invention of the wheel, man has cursed the mud and devised ways to defeat it. Materials have evolved from Roman stone roads, to cobblestone streets, to concrete and asphalt pavements. Pavements act as a roof over the road base. If water gets under this roof, it loses its support and will fail. With asphalt, this is the beginning of the dreaded Pothole.

• Concrete pavement is basically a mixture of rock and sand held together by Portland cement. When water is added a chemical reaction takes place. The mud must be placed and finished before the reaction is too far along or it will lose its strength.

  In the chemical reaction heat is produced, the water evaporates, and a rigid (rock-like) pavement results. For some applications wire mesh, rebar or fiber mesh are included in the pavement for additional strength. Concrete does not bend. It is strong but brittle. It is especially useful for water courses (drain pans, curb and gutter) and high weight loading areas (dumpster pads). It is more expensive to install than asphalt but is a wise investment for certain locations.

• Asphalt pavement is a mixture of rock and sand held together by liquid asphalt cement. Liquid asphalt is a product of crude oil refining. It is heated and combined with the aggregate at a temperature of over 300 degrees. It is placed and compacted while hot and, when cooled, a flexible (spring-like) pavement results. Asphalt will bend with traffic loads and with expansive soils. If these factors are greater than the pavement is designed to withstand, it may crack or break instead of returning to its original shape. This kind of damage is commonly seen at dumpster loading areas and in parking stalls.

• Cracking in concrete can happen during the curing process. As the water evaporates the concrete may shrink. For that reason, control joints are placed at intervals to provide uniform weak points for the pavement to crack. After curing, overloading or a poor base under the pavement may also cause it to crack and break.

  Cracking in asphalt generally occurs as it ages. Exposure to the sun evaporates the light volatiles from the liquid asphalt that binds the aggregate together. This causes shrinking and eventually the asphalt pulls apart at a weak point. Control joints are not used in asphalt to guide this cracking as they are in concrete.

  Heavy loads are another cause of cracking in asphalt. They can compress the asphalt beyond its design, breaking the bond, and leaving cracks.

III. DAMAGE TO ASPHALT PAVEMENTS

The ultimate goal in asphalt pavement maintenance is to protect the surface from the elements and to prevent water from infiltrating through cracks into the base.

Nearly everything that contacts asphalt is bad for it.

• Vehicles can cause compression damage from overloading

• Car tires can, especially on turns, scrub away the finer aggregates from the pavement surface leaving a rough texture and a weaker pavement.

• Oil and fuel spills, which are petroleum products like the asphalt cement, can soak into and soften the pavements so the aggregate isn't bound together as good as it was originally.

• Water can cause damage several ways. As it runs across the pavement from sprinklers, (a daily occurrence 6 to 8 months a year), rain and snow melt it washes away the fines from the top of the pavement creating a rougher surface

• Water penetrating the pavement through cracks can cause damage in both warm and cold weather. In warm weather it soaks down into and softens the base under the pavement. Since asphalt is flexible, vehicle traffic will cause it to move up and down over the soft base and pump out the base. This creates a void under the pavement and allows it to fail under the weight of the vehicles on top.

• In cold weather you have the same expansion and contraction scenario plus the freeze - thaw action that can create the void under the pavement without the need for vehicles on top.

IV. PREVENTIVE MAINTENANCE

Parking lots represent a sizeable investment. The best and most cost efficient way to maintain this investment is to conduct various asphalt maintenance procedures on the lots periodically.

• The ultimate goal in pavement maintenance is to avoid water intrusion and to protect the surface from the elements. Asphalt generally cracks from the bottom up so when cracks appear on the surface they are full depth and will allow water to penetrate to the base.

• Cracks should be filled at least every other year. The rubberized material is designed to adhere to the sides of the crack, expand and contract with the temperature fluctuations, and keep moisture away from the base. Following crack filling, a coal tar sealer should be applied. Sunlight and chemical spills such as oil and gasoline prematurely age asphalt pavement.

• Sealcoating helps to eliminate the intrusion of water, sunlight and chemical spills. It seals in, and helps prevent the evaporation of, the liquid asphalt that is binding the pavement together. This helps to prevent the pavement from shrinking and becoming brittle, and holds in the finer aggregates better so the surface stays smooth. The jet black finish also adds to the curb appeal of the property.

• Crack filling and sealcoating are not repairs. Their purpose is to lengthen the life of the pavement and lessen the cost and frequency of repairs.

  When repairs are needed, quick attention can also be considered preventative maintenance by keeping the area from getting larger and therefore being more costly to repair.

• Yearly repairs, crack filling every two years and sealcoating every three to four years will cost approximately one third that of unmaintained pavement. These cost benefits are in addition to fewer complaints from customers and tenants, lower trip-hazzard problems and improved curb appeal. The first thing a prospective customer or tenant sees may be the last thing that you notice.

V. REPAIRS

There are three main options for repairing asphalt pavements.

• The least expensive is a surface patch where the area is cleaned, any loose debris is removed and a tack coat is applied. Hot-mix asphalt is placed in the hole and compacted and another layer is placed over the hole and surrounding area to seal it. There is no cutting involved, very little material to haul away and a relatively small amount of new asphalt needed.

  This process is best used where no cracks are evident such as an area where water and traffic have worn away the pavement and it is not broken or sunken. Another area would be where part of an overlay has popped off and can be patched in.

• In areas where the pavement is sunken, heaved up, or cracked into an "alligatored" pattern it is necessary to remove and replace the existing asphalt from the base up. The damaged asphalt is cut out and hauled away, the base material is graded and compacted and new hot-mix asphalt is placed in at least two layers and each layer is compacted. A surface patch doesn't work here because the cracks extend through the pavement to the base and will reappear unless a full depth repair is performed.

• When asphalt has reached a point where it has lots of patches, cracks and otherwise is showing its age, an overlay may be called for. The existing pavement is repaired to a point where it will provide a solid base for the overlay, and then two inches of hot-mix asphalt are placed and compacted.

  In some instances a paving fabric is incorporated with the overlay to separate the new asphalt from the old, cracked asphalt.

VI. PURCHASING PARKING LOT SERVICES

In order to get a proposal that fits the needs of the pavement it is best to know the condition of the parking lot. The best way to do this is to periodically walk the lot and make notes or indicate on a site plan areas of concern. Having accurate site plans and notations of major concerns available for the contractor is a good starting point and will improve the usefulness of the subsequent proposal.

If overseeing asphalt repair is a new experience (or if you are on a new property), it may help to look over old proposals to familiarize yourself with the history of the property and the terminology used. They may also be a source of questions on terminology and processes that can be cleared up when meeting with the estimator.

Formulate an idea of the extent of the maintenance or repairs that the budget will allow to be included in the bid.

• Is the main concern potholes?

• Is curb appeal a concern?

• Is the lot in need of an extensive overhaul?

Try to set aside time to walk the lot with the contractor. This allows both parties to note concerns and questions about specific areas to be included in the proposal.

Conclusion: Asphalt maintenance and repair is a positive for your pavement, for your property, and can be for you, too.

Allens Asphalt is here to answer questions, explain our services, give informed advice, and provide quality service.

And, in one persons opinion, Santiago's green chile is a killer (and I mean that in a good way)!