Asphalt Parking Lot Planning To Reduce Future Failure Issues

Paved parking lots are essential to many businesses so that customers can comfortably and easily visit your establishment. However, if your parking lot has failed and is covered in pot holes, cracks, and sink holes, then individuals may simply avoid your business altogether. While some parking lots can simply be repaired, others need to be repaved. If repaving is completed, then your contractor should spend time planning out the driveway properly. There are certain things that you should ask for if you do not want the asphalt to sink or fall in the future. 


The subgrade soil that sits beneath your asphalt needs to be kept dry or the asphalt can sink in either weak areas or spaces that retain the most stress from vehicles that park on your parking lot. However, if you also want to retain landscaping to beautify your business, then sprinklers and irrigation systems may be added to help hydrate grass and plants on islands and parking lot perimeters. In this case, drainage needs to be a part of the paving plan.

There are a few different types of drainage considerations that come into play during parking lot planning; underdrainage and provisions above the asphalt. Underdrainage consists of a subsurface system that moves water quickly away from the subgrade before the soil has an opportunity to absorb the fluid. The drainage system should be secured during the excavation and initial rebuild stages of the asphalt paving. Underdrains usually consist of a perforated conduit covered with landscape fabric. This type of formation is similar to drain tile that is installed on residential properties. 

Provisions above the asphalt that assist with drainage include an overall but gradual decline. In many cases, the decline should only be about 2% to 5%. For larger parking lots, a 2% slope is more likely and practical, since this can allow the edges to meet the ground along the edges without causing a noticeable hill towards the center of the parking lot. In some cases, cross-sectional drain lines may be needed along the center portions of the pavement to help direct water flow more consistently towards the edges.

Soil Preparation

You may understand that the strength of the subgrade is vital to the strength of the asphalt that sits on top. This is one reason why several inches to a foot or more of vegetation, soil, and rock is removed from underneath the excavated asphalt. While aggregate material will provide a lot of the strength to the asphalt above, your installation plan should outline soil preparation tactics before the aggregate is spread. 

Soil preparation should start with testing and additional excavation and soil replacement. This is wise in situations where soil content is hard or rocky. In addition to possible replacement, the asphalt specialists should apply something called a soil sterilant. This sterilant may be skipped by some asphalt professionals, but it is helpful to stop vegetation and plant growth underneath the asphalt. Plants can create openings in the soil where the asphalt above can fall. Also, plants can work their way up towards the surface and grow through cracks.

Once the soil is prepared, fabric should be set down. This can further prevent plant growth, minimize drainage through the soil, and add security. Specifically, the fabric can keep both the soil and the secured aggregate from shifting. 

When aggregates are placed, they should be untreated. Untreated means that the rock material has not been cleaned or rinsed in advance. Small bits of debris will then collect between the rocks and act as a sort of cement to keep this later secure and strong. 

If you have concerns about future issues concerning your asphalt parking lot, you should speak with your paving professional. This individual can help you to understand some of the other types of planning and practices that take place to ensure longevity.