The single most common mistake we see with rigid pavement design in Shreveport is treating the subgrade like it’s anywhere else. It’s not. You get a concrete slab looking perfect on paper—until four wet-dry cycles later, the clay underneath swells, shrinks, and the slab cracks at the joints. Shreveport sits on Pleistocene terrace deposits and alluvial silty clays that can push plasticity indices past 35. When you skip a proper Atterberg limits analysis or assume a generic k-value from a textbook, you’re setting the pavement up for distress within the first three years. Our approach starts with the soil, not the slab, and works upward from there.
In Shreveport, the subgrade k-value can drop by half between a dry August and a wet February. Slab thickness has to match the worst case, not the average.
Process and scope
Site-specific factors
The Eocene-age Cook Mountain Formation underlies much of Shreveport’s southern half—a mix of glauconitic clay and silt that turns to soup when saturated. Combine that with a groundwater table often at 3 to 5 feet and a city that averages 51 inches of rain a year, and you have a recipe for pumping failures at transverse joints if the base layer isn’t free-draining. Curling stresses at slab corners spike when daytime highs hit 95°F and nighttime lows drop 25 degrees, which happens regularly here in late spring. A rigid pavement design that ignores thermal gradient—or worse, relies on a single temperature assumption—will open up at the joints within the first two seasonal cycles. We model the temperature differential explicitly and tie dowel diameter to expected slab movement, not a standard table.
Standards used
ACI 360R – Guide to Design of Slabs-on-Ground, PCA – Thickness Design for Concrete Highway and Street Pavements, ASTM D1586 – Standard Test Method for Standard Penetration Test (SPT), ASTM D2487 – Classification of Soils for Engineering Purposes, IBC Chapter 18 – Soils and Foundations
Complementary services
Subgrade Evaluation for PCC Pavement
Field CBR and plate load tests to establish the modulus of subgrade reaction (k) across the site. We correlate with lab Atterbergs and moisture-density curves to predict seasonal k-value loss.
Thickness & Joint Design
Pavement thickness per PCA and ACI 360R, including dowel and tie bar schedules, joint spacing plans, and reinforcing steel layout for crack control in Shreveport’s expansive clay environment.
Drainage & Base Course Specification
Cement-treated or open-graded base design to intercept rising groundwater and prevent pumping at slab joints. Gradation specs tied to local aggregate availability from the Red River gravel sources.
Typical parameters
FAQ
Why does rigid pavement in Shreveport crack so soon after construction?
The biggest culprit is moisture-sensitive clay subgrade. When the subgrade swells during wet months and shrinks during dry spells, the slab loses uniform support. Without a stable base course and proper joint load transfer, corners and edges crack under traffic. Our designs address this with a moisture-stable subbase and conservative joint spacing.
What thickness of concrete pavement do you typically recommend here?
It depends on the subgrade k-value and the expected traffic loading, but most industrial and commercial pavements in Shreveport end up between 7 and 9 inches. Residential driveways can work at 5 or 6 inches if the subgrade is treated. We never give a number without seeing the soil data first.
How do you account for Shreveport’s high groundwater in the design?
We measure the water table depth during the geotechnical investigation—usually between 3 and 5 feet in the valley areas—and design a free-draining base layer that prevents water from accumulating under the slab. The goal is to eliminate pumping at joints, which is the primary failure mechanism in wet subgrade conditions.
Do you use dowel bars in all rigid pavement designs here?
For any pavement carrying truck traffic or heavy forklift loads, yes. Dowel bars transfer shear across joints and prevent faulting. We size the dowels based on the expected slab movement from thermal curling and moisture warping, not just a prescriptive table.
What is the typical cost range for a rigid pavement design package in Shreveport?
For a standard commercial lot or industrial yard, the full design package—including field investigation, lab testing, and the stamped pavement report—falls between US$2,020 and US$6,290 depending on the number of borings and the complexity of the subgrade conditions.