Fort Zimwalt School District in O’Fallon, Missouri, USA,
recently discovered long-term savings & benefits
pay well with the decision to GO CONCRETE!
As flowers bloom in spring and school graduations roll around, one thing that remains constant for school facilities administrators is the appearance of cracks in the acres of asphalt paving that they are responsible for maintaining. Among the big decisions a school district makes on a regular basis, choosing how it goes about paving/re-paving its parking lots wouldn’t seem to have a place on that list. However, this decision has more implications than meet the eye, as an uninformed one may cost the taxpayers more than necessary over time. Although other factors are at play, the decision usually comes down to the immediate savings asphalt provides versus the long-term savings concrete overlays provide:
Concrete Overlays—The Best Choice for Durable Pavement Overlays:
A deteriorated asphalt parking lot, full of potholes and puddles, is both
an eyesore and a safety hazard to everyone who uses it. Owners can transform
a rutted asphalt surface into an attractive, functional parking area
by covering it with a concrete overlay, or whitetopping (NRMCA 2011): www.concreteparking.org/whitetopping/http://concreteparking.org/whitetopping/
Concrete Overlays Design of Concrete Overlays for Ashpalt Parking Lot
Parking area joint layout—Joints in concrete parking areas aid construction and minimize uncontrolled cracking. They can also delineate parking areas and traffic lanes. Designing a joint layout requires good judgment based upon a few basic rules. Figure 2 shows a typical parking area that employs the following guidelines (NRMCA 2011):
http://concreteparking.org/whitetopping/overlaybrochure.html
20 projects over a dozen years was evidence that the
Fort Zumwalt School District made the right decision,
& they haven’t regretted it since!
Although the initial investment in concrete was more than asphalt, the savings from choosing concrete have been realized over the course of time through:
• Maintenance cost reduction
• Overall longevity of the asset
• Estimated that going with concrete would save 43% over asphalt over the life of the asset
• Avoided costly headaches that come with asphalt:
– seal coating
– additional overlays
– regular maintenance
Lisa Koester, Director-Construction Renovations and Building Systems-Fort Zumwalt School District (joined district in 2000; Director in 2015) is responsible for 25 schools and 9 support buildings. Fort Zumwalt schools and student support centers comprise 2.5 million square feet of floor space, and roof space.
As a way to circumvent the relentless maintenance required by asphalt surfaces, Lisa said, “My predecessor started working with Bax Engineering and The Concrete Council in 2008 to go over the top of the asphalt with concrete.” So far:
• Largest project completed in phases
— Phase 1 in 2010 at a total cost of $197,503 (7,700 sq. ft.)
— Phase 2 in 2012 at a total cost of $716,218 (23,600 sq. ft.)
• Smallest concrete overlay consisted of just a portion of a parking lot
— Completed in 2018 at a total cost of $150,000 (3,545 sq. ft.)
Koester said that — with some protocols that her team has implemented over time — the process is relatively straightforward and simple:
• Minimal surface preparation
• Concrete is poured over the existing asphalt
• Finished pavement is saw-cut, then
• Sealed
Koester encouraged facilities administrators to develop solid partnerships with consultants and to establish procedures to ensure success. Besides a basic cleaning and inspection of the surface to be overlaid, Koester said that Zumwalt has SCI do soil tests. Underlying water needs to be avoided, as it can turn to steam in 100-degree temps, causing the pavement to lift. She advises resloping some steep areas and putting in lugs to prohibit sliding in severe slopes.
She added that it is important to have good concrete contractors in place (Fort Zumwalt works with three). The district’s engineering partner Bax Engineering provides oversight of the installation and saw cuts to make sure that specs are met.
Fort Zumwalt School District. Click to enlarge.
The Concrete Council offers a design assistance program for owners. The Council also provides financial modeling for public institutions that allow them bank the savings from what would be spent on asphalt maintenance to pay off construction cost through Certificates of Participation (similar to a lease), which can be approved by a simple vote of the governing body.
For the Construction Forum online magazine article, please go to: www.constructforstl.org/concrete-overlays-help-fort-zumwalt-school-district-stay-on-top-of-paving-costs/