Slipform Curb Installation: Step-by-Step 2026 Spec Guide
Direct Answer (60 words): Slipform curb is installed by a self-propelled paver that extrudes concrete continuously through a steel form box, leaving a fully shaped curb behind it. A trained crew using a Power Curbers 5700-D produces 50 to 100 linear feet per hour at a 1/4-inch grade tolerance. The pour requires a 1 to 2 inch slump mix and a compacted 95 percent Proctor base.
Slipform paving is the production engine behind every commercial parking-lot curb run over a few hundred feet. The machine carries the form, the concrete, and the line-and-grade reference in one chassis, then walks the entire run pouring a continuous shape. The construction efficiency only works when the subgrade, the mix, and the operator settings are dialed in together. This guide covers the full sequence we use on Salem and Portland-area commercial work.
What is slipform curb?
Slipform curb is concrete extruded through a steel form box mounted on a self-propelled paver. The Federal Highway Administration documents slipform paving as the standard high-production method for curbs, gutters, and barriers on highway and commercial work (FHWA Pavement Design). The output looks like the final curb the moment it leaves the form: no stripping, no patching, no second pass.
Slipform curb vs extruded curb: are they the same?
The two terms overlap in casual contractor talk, but they describe different equipment classes:
| Feature | Slipform Paver | Extrusion Machine |
|---|---|---|
| Track width | 6 to 12 ft | 4 to 6 ft |
| Production rate | 50 to 100 lf/hr | 30 to 50 lf/hr |
| Profile size capability | Up to 8 ft barrier | Up to 24-inch ribbon |
| Reference system | String line + sensor wand | String line + sensor wand |
| Best fit | High-volume commercial | Mid-volume commercial |
What machine do we run?
We run a Power Curbers 5700-D, the model widely cited in commercial curb work. It carries an 18 to 25 cubic-foot hopper, a 6 to 12 inch tall form box capability, and a four-string sensor mast for line and grade. ODOT references the 5700-D class machine in its guidance for curb-and-gutter placement (ODOT Standard Specifications, Section 00759).
How do you prepare the subgrade for slipform?
Subgrade tolerance is what separates a clean slipform pour from a wavy curb that gets rejected on inspection.
- Compact to 95 percent Proctor per ASTM D1557.
- Trim the base to plus or minus 1/2 inch of design grade.
- Verify with a stringline check before the machine arrives.
- Remove organics and frozen material. Replace with crushed aggregate to the project frost depth (12 to 18 inches in Oregon's I-5 corridor).
- Wet the subgrade ahead of the machine on hot days to prevent moisture loss from the bottom of the curb.
How do you set the line and grade?
Slipform machines reference a taut string line on both sides of the form box. The string controls horizontal alignment, vertical grade, and slope simultaneously.
- Set steel line pins every 25 feet.
- Pull a nylon mason's line at the design top-of-curb plus the sensor offset.
- Walk the line, sight for sag, and pull tighter at any low spot.
- Flag every transition (radius start, joint location, ramp tie-in) on the line itself.
ODOT 00759 limits surface tolerance to 1/4 inch in 10 feet and alignment to 1/2 inch from the design line.
What concrete mix design works for slipform?
A slipform mix is a low-slump, high-fines concrete that holds its shape the moment the form box releases.
| Mix Property | Spec |
|---|---|
| Compressive strength | 4,000 PSI at 28 days (ODOT Class 4000) |
| Slump | 1 to 2 inches |
| Maximum aggregate | 3/8 to 1/2 inch |
| Air entrainment | 5 to 7 percent |
| Cement content | 564 to 658 lb/cy |
| Water-cement ratio | 0.40 to 0.45 |
How do you operate the slipform paver?
- Stage trucks ahead of the machine. Cycle time should keep the hopper at half-full or better.
- Engage the auger and drive. The 5700-D walks at 50 to 100 lf/hr in commercial mode.
- Watch the form box. A trailing inspector flags any tearing, sagging, or cap voids.
- Cut joints in real time. A trailing crew member tools control joints every 10 to 15 feet.
- Run a finisher behind the paver. A broom finish gives the cap traction.
How do you handle radii and ramps?
Tight radii under 25 feet inside cannot be slipformed. Stop the machine, hand-form the radius with traditional lumber, then restart the slipform run on the next tangent. ADA curb ramps tie into the slipform run via a pre-formed transition block placed before the machine reaches the ramp station.
How do you cure and protect a slipform curb?
Cure with a sprayed curing compound (ASTM C309 Type 2) within 30 minutes of finish. The American Concrete Pavement Association documents that early curing is the single biggest predictor of long-term curb durability (ACPA).
- Day 1: No traffic. Cure compound or wet burlap.
- Day 2 to 7: Light foot traffic only.
- Day 7 to 14: Vehicles allowed if cap shows fingernail-resistance.
- Day 28: Full design strength. Snowplow and lateral-impact safe.
What does slipform curb cost?
Industry Baseline Range
| Component | Range |
|---|---|
| Slipform curb installed (commercial) | $9 to $16 per linear foot |
| Mobilization | $1,200 to $3,500 per project |
| Subgrade prep | $2 to $5 per linear foot |
| Joint sealing | $1 to $2 per linear foot |
Current Market Reality
2026 fuel prices, equipment service rates, and ready-mix delivery surcharges have pushed Oregon slipform pricing up 12 to 20 percent over historical baselines. Mobilization costs hit small projects under 1,000 linear feet hardest because the slipform paver is sized for sustained production.
Real install reference
In February 2026 we slipformed 4,800 linear feet of 6-inch barrier curb at a Salem retail center off Lancaster Drive. The crew set the line on a Tuesday, slipformed the run in a single 9-hour production day on Wednesday, and tooled joints behind the machine. Final inspection measured 1/8-inch surface tolerance. The owner's structural engineer signed off on the first walkthrough.
Frequently Asked Questions
What is the production rate for slipform curb? A trained crew on a Power Curbers 5700-D produces 50 to 100 linear feet per hour on tangent runs. Daily output runs 400 to 800 linear feet for commercial parking-lot work, depending on truck cycle time and joint-tooling complexity.
Can slipform curb be poured on tight radii? No. Slipform pavers cannot negotiate radii under 25 feet inside. Sharp radii are hand-formed traditionally, then the slipform run picks up on the next tangent.
Does slipform curb need rebar? Standard 6-inch slipform barrier curb does not require continuous rebar in most parking-lot applications. Heavy-duty 8-inch curbs and integral curb-sidewalk pours include #4 longitudinal rebar per ACI 318.
What tolerance does Oregon DOT require? Oregon DOT Standard Specification 00759 sets surface tolerance at 1/4 inch in 10 feet and alignment tolerance at 1/2 inch from the design line for slipform curb in commercial applications.
How long before slipform curb can take vehicle traffic? At 24 to 48 hours the curb resists fingernail pressure and can take adjacent paving traffic. Full design strength is reached at 28 days. Snowplow contact during the first 7 days will spall the cap.
We run slipform curb across the Willamette Valley and Central Oregon. To plan your run, start with our concrete curb guide, the extruded curb installation walk-through for shorter projects, or get a quote on curbing in Salem Oregon.