Pour Strip Zero
Reinforced concrete slab at a construction joint where a closure pour leave-out would traditionally sit open

Closure Pours and Delay Strips, and How PS=Ø Eliminates Them

What a closure pour is, why the leave-out sits open for weeks, the four names crews use for the same detail, and the mechanical rebar splice that removes it on reinforced and post-tensioned structures.

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One Detail, Four Names

The closure pour, the delay strip, the pour stop, the shrinkage strip: same leave-out, different label.

A closure pour is the strip of concrete left out at a construction joint and cast later, so the slabs on either side can shrink before the connection is made. Most guides define the term and stop there. Ours starts from what our engineers actually detail on live decks: closure pour, delay strip, pour stop, and shrinkage strip are four names for one detail, and every one of them leaves reinforcement exposed in an open gap for weeks on the critical path. That open leave-out is exactly the thing PS=Ø was built to remove. Our couplers and closure strip go in where the pour stop would sit, so the slab still shortens naturally but the crew is never leaving an open joint. PS=Ø is an ICC Approved, ACI 318 Type 1 and Type 2 compliant mechanical rebar splice engineered over 45 years to keep the reinforcement continuous across that seam.

What is a closure pour?

A closure pour is a strip of slab left out on purpose at a construction joint, then cast later once the adjacent concrete has done most of its drying shrinkage. Leaving the gap open lets the two sides shorten independently, so restraint-to-shortening does not build up and crack the finished slab. The reinforcement is left exposed across that open strip until the closure is poured. It is one member of the family of concrete movement joints, and the one tied specifically to sequencing placements.

That return trip is where PS=Ø changes the sequence. Instead of leaving the strip open and coming back to fill it, the reinforcement is spliced mechanically across the seam. The slabs still shorten and cure naturally, then the couplers are grouted to complete a continuous connection. You can see the full assembly on our system page, where the couplers and closure strip replace the traditional pour strip and closure pour.

The Vocabulary

Closure pour vs delay strip vs pour stop vs shrinkage strip

These four terms get used interchangeably on jobsites, and for good reason: structurally, they are the same detail. What changes is who is saying it and where. Here is how the vocabulary breaks down, and why it all points at one leave-out PS=Ø removes.

Closure pour

Also called: closure strip, closure joint

The concrete placed later to close a gap that was left open on purpose. The leave-out itself, and the pour that fills it, both get called the closure pour.

Delay strip

Also called: delayed pour strip, pour strip

A strip of slab intentionally left out and cast later so the two sides can shrink first. The most common term for the same detail on cast-in-place structures.

Pour stop

Also called: pour break, day joint

Where the day's placement stops. On the field it becomes the closure line the crew comes back to fill once the adjacent concrete has done most of its shrinking.

Shrinkage strip

Also called: restraint-to-shortening strip

A closure strip named for its job: relieving restraint-to-shortening by letting the slabs on either side shorten before the strip is cast to lock them together.

The takeaway for a detailer: it does not matter which of these words is on your drawings. If the design carries a leave-out at a construction joint to relieve restraint-to-shortening, that is the detail PS=Ø is engineered to replace. Not sure what your set calls it? Call (800) 355-8414 and our engineers will read the sheet with you.

Why a closure pour sits open on the critical path for weeks

The whole point of a closure pour is to wait. The strip stays open, commonly 30 to 60 days, so the adjacent slabs can shorten before they are tied together. That wait is baked into the schedule, and the open gap affects every trade that has to cross it. Here is the traditional sequence against the PS=Ø sequence.

Stage Traditional closure pour / delay strip PS=Ø splice
At the joint Strip left out, reinforcement exposed in an open gap Couplers and closure strip set where the leave-out would sit
While the slab shrinks Weeks of waiting, gap open on the critical path Slab shortens naturally, off the critical path
Other trades Work around an open gap collecting debris Cross a self-supporting seam, no leave-out
Closing it Return trip to form and pour the closure strip Grout the couplers, seam is continuous

Every closure pour is a place the reinforcement is interrupted, water can enter, and a return crew has to be scheduled. That is the trade the industry has accepted for decades. The alternative is not to detail the strip more carefully, but to keep the reinforcement continuous so the leave-out never has to sit open. For the expansion-joint side of the same argument, see our page on the closure pour at a construction joint and how expansion joints are eliminated.

How PS=Ø eliminates the closure pour

PS=Ø replaces the open closure pour with a self-supporting mechanical splice. The slab still shortens and cures on its own timeline, so you keep the movement the delay strip was there to provide, but the reinforcement stays continuous and the joint closes with a grout, not a return pour. Here is the sequence at a high level.

  1. 1

    Engineered shop drawings

    Our engineers detail the splice into your structural design so it carries the reinforcement across the seam where a closure pour or delay strip would otherwise interrupt it.

  2. 2

    Couplers set where the pour stop would sit

    The couplers and closure strip go in exactly where the leave-out would sit, so crews are not leaving an open gap and exposed rebar across the deck for the trades to work around.

  3. 3

    The slab shortens and cures naturally

    The concrete goes through its natural volume change off the critical path. No 30 to 60 day open strip, no waiting on a closure pour to keep the schedule moving.

  4. 4

    Grout the couplers to close the seam

    Once shrinkage is complete, the couplers are grouted to finish a continuous, ICC Approved, ACI 318 Type 1 and Type 2 compliant connection. The closure pour is gone.

End view of a PS=Ø mechanical rebar coupler that replaces the closure pour at a construction joint

The method has been used to eliminate closure pours and delay strips on live commercial jobsites including Gaylord Pacific, The Ottawa Hospital, and IU Health Downtown. See more on the case studies page, then call (800) 355-8414 to talk through your structure.

What removing the closure pour changes on the jobsite

Taking the closure pour out of the sequence changes the day for everyone who touches the slab. Engineers hold structural intent without detailing an extra leave-out. Placement and finishing crews pour continuously and skip the return trip to close the delay strip. For a crew-level view of how that plays out, read what eliminating the leave-out means for placement and finishing crews.

Want the full mechanics of the seam, the couplers, the closure strip, and the grouting that replace the leave-out? Our system page walks through the couplers and closure strip that replace the closure pour and how the whole assembly installs.

Questions Engineers Ask

Closure pour FAQ

What is a closure pour in concrete? +
A closure pour is the section of concrete left out at a construction joint and cast later, after the slabs on either side have shrunk. Leaving the strip open lets the adjacent concrete go through most of its drying shrinkage first, so restraint-to-shortening does not crack the finished slab. The reinforcement sits exposed in that open leave-out until the closure is poured. It is the same detail engineers also call a delay strip, pour strip, pour stop, or shrinkage strip. PS=Ø replaces that open leave-out with an ICC Approved, ACI 318 Type 1 and Type 2 compliant mechanical rebar splice that keeps the reinforcement continuous while the slab still shortens naturally.
What is the difference between a closure pour and a delay strip? +
There is no structural difference. Closure pour, delay strip, pour stop, and shrinkage strip all describe the same thing: a strip of slab left out at a construction joint and cast later so the adjacent concrete can shrink first. Which name a project uses comes down to region, trade, and habit. A structural engineer might spec a delay strip, a superintendent calls it the closure pour, and the concrete crew calls it the pour stop. PS=Ø targets that one detail regardless of what it is labeled on the drawings.
How long does a closure pour stay open? +
Traditionally a closure pour or delay strip is left open for weeks, commonly cited as 30 to 60 days, so the adjacent slabs can complete most of their drying shrinkage before the strip is cast. The exact window depends on the mix, curing conditions, span, and how much restraint-to-shortening the engineer of record needs to relieve, so the final number belongs to the design team. During that whole period the leave-out sits open on the critical path with exposed rebar, and other trades have to work around the gap. PS=Ø removes that wait by carrying the reinforcement across the seam with a mechanical splice, so the concrete still shortens but the joint does not sit open blocking the schedule.
Can you eliminate closure pours on post-tensioned slabs? +
Yes. Post-tensioned slabs shorten more than conventionally reinforced ones because the tendons actively compress the concrete, which is exactly why PT structures rely so heavily on closure strips and delay strips to release that shortening. PS=Ø is engineered for reinforced and post-tensioned work: the splice lets the slab shorten and cure naturally, then the couplers are grouted to complete a continuous, code-compliant connection. That eliminates the open closure pour without eliminating the movement the strip was there to allow.
Do you still need a closure pour if you use PS=Ø? +
No open leave-out. PS=Ø replaces the traditional open closure pour with a small grouted closure strip built around the couplers. The couplers and closure strip go in where the pour stop would sit, so the crew is not leaving an open gap with exposed rebar across the deck. The concrete on either side still shortens as it would with a delay strip, then the couplers are grouted to close a continuous, ICC Approved, ACI 318 Type 1 and Type 2 compliant connection.
Is a closure pour a type of construction joint? +
Yes. A closure pour lives at a construction joint, the stop-and-start line between two placements poured on different days. The construction joint is the interface; the closure pour is the strip of concrete left out at that interface and cast later. It sits alongside expansion, contraction (control), and isolation joints in the broader family of concrete movement joints, but it is the one specifically tied to sequencing placements and relieving shrinkage before the connection is made.
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Design the Closure Pour Out of Your Next Slab.

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