Case Study: Brownstown School Parking Lot

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Case Study Overview

Project: Brownstown School Parking Lot
Location: Brownstown, IL, United States
Project Type: Parking Lot
Application: Separation and Stabilization 
Product Used: GEOTEX® 200ST

Photo of Brownstown Elementary School parking lot construction in progress.

Problem

In the Spring of 2000, Brownstown Elementary began work on a new parking lot. For the project, the Brownstown, Illinois school district contracted Rooters American Maintenance Inc. Just after initial construction began, Rooters quickly realized that they were faced with an common problem when constructing paved parking lots and roadways-soft, wet subgrades. They knew the issue had to be addressed before construction of the road began in order to avoid future pavement failure and costly maintenance.

It is well known that if not corrected, subgrades with high moisture content will contaminate approximately 10% of the aggregate base thickness during construction. Fine soil particles will continue to move up from the subgrade under dynamic loading, ultimately weakening the aggregate layer and over time, lead to overall pavement failure. Many contractors will waste time and money either “farming” the soil to get it dry enough to establish a stable work platform or removing and replacing the soft subgrade with select fill or chemical stabilization products. Rooters did not. They chose to use a geotextile between the soil subgrade and aggregate layer. By providing permanent separation, geotextiles allow the individual layers to maintain their original strength and structural integrity.

Solution

The product Rooters selected was a woven slit film geotextile, GEOTEX® 200ST produced by Propex®. The polypropylene woven fabric with low elongations and a tensile strength of 200 lbs. is packaged in 12.5' x 432', 15' x 360' and 17.5' x 360' rolls and is easy to install by hand, making it ideal for this type of construction. After clearing the site and smoothing the subgrade, Rooters simply laid rolls of GEOTEX® 200ST across the subgrade with overlaps along the row. Propex® recommends overlaps of no less than 12" on stable soils and up to 36" of overlap on soft soils. Aggregate was then deposited over the geotextile and spread by a grader to a thickness of 12 inches. The layers of subgrade and aggregate were immediately separated ultimately providing long-term pavement performance. After the base was compacted, the parking lot was paved and ready to withstand the heavy load of vehicle traffic.

Woven geotextiles, like GEOTEX® 200ST, have a remarkable capacity for filtering soils, distributing loads, reducing rutting and extending the life of paved lots. Made from individual yarns woven together to provide a dimensionally stable geotextile, GEOTEX® 200ST is resistant to ultraviolet (UV) degradation and to biological and chemical environments normally found in soils. GEOTEX® 200ST is backed by decades of in-field performance in everything from separation and filtration to erosion control and waste containment applications.

Photo of Brownstown Elementary School parking lot construction in progress.

Solution

The product Rooters selected was a woven slit film geotextile, GEOTEX® 200ST produced by Propex®. The polypropylene woven fabric with low elongations and a tensile strength of 200 lbs. is packaged in 12.5' x 432', 15' x 360' and 17.5' x 360' rolls and is easy to install by hand, making it ideal for this type of construction. After clearing the site and smoothing the subgrade, Rooters simply laid rolls of GEOTEX® 200ST across the subgrade with overlaps along the row. Propex® recommends overlaps of no less than 12" on stable soils and up to 36" of overlap on soft soils. Aggregate was then deposited over the geotextile and spread by a grader to a thickness of 12 inches. The layers of subgrade and aggregate were immediately separated ultimately providing long-term pavement performance. After the base was compacted, the parking lot was paved and ready to withstand the heavy load of vehicle traffic.

Woven geotextiles, like GEOTEX® 200ST, have a remarkable capacity for filtering soils, distributing loads, reducing rutting and extending the life of paved lots. Made from individual yarns woven together to provide a dimensionally stable geotextile, GEOTEX® 200ST is resistant to ultraviolet (UV) degradation and to biological and chemical environments normally found in soils. GEOTEX® 200ST is backed by decades of in-field performance in everything from separation and filtration to erosion control and waste containment applications.

Photo of Brownstown Elementary School parking lot construction in progress.

Performance

Rooters selection of Geotex® 200ST is proving to be a wise investment by the Brownstown, Illinois school district. Six years after the project was completed, Geotex® 200ST is still performing under heavy traffic loads and there are no signs of pavement failure. By avoiding costly maintenance, Brownstown Elementary can focus on funding the education of many more generations of studens and not parking lot repair.


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