Our revolutionary mechanical reinforcement splice system is a new idea for many in the construction industry. Consequently, we hear a handful of objections when it comes to implementing PS=Ø®. In this blog, we take time to address the top objections from engineers, concrete contractors, and general contractors about PS=Ø® technology.
Engineers
Objection: “You can’t develop the full tensile strength of rebar in the PS=Ø® coupler.”
Response:
Actually, we can!
With a thread on one end of the coupler and a grout-filled sleeve on the other, PS=Ø® utilizes two ACI-permitted mechanical coupler technologies that have been successfully used for decades. Threaded technology originated in the 1980s and commonly appears in cast-in-place concrete where lapping rebar is prone to congestion. Grouted technology dates back to the late 1960s and is primarily used to connect pieces of precast concrete to each other, or to cast-in-place concrete.
Like other threaded and grouted couplers, PS=Ø® has undergone rigorous ICC-ES AC133 testing criteria. It meets Type 1 and Type 2 mechanical splice requirements as specified by IBC and ACI 318, and is ICC-approved.
The full strength of the reinforcement is developed through the thread at one end and the grouted sleeve at the other, using a high-strength, non-shrink grout.
Objection: “I don’t see how PS=Ø® is different from other threaded/grout-filled sleeve couplers on the market.”
Response:
Traditional threaded/grout-filled sleeve couplers on the market were specifically designed for the precast concrete industry. Where they connect pieces of precast concrete to each other, or to cast-in-place concrete and do not allow for temporary movement.
In other words, they’re designed for a static condition where the rebar that goes into the grouted sleeve is fully inserted into the coupler and grouted right away.
PS=Ø® is different in that it’s specifically designed to replace a pour strip lap splice. The system allows for temporary, dynamic movement in cast-in-place concrete.
It’s designed to accommodate temporary movement by allowing for concrete shrinkage between two separate pours. The continuation rebar starts out fully inserted into the grout-filled sleeve, but as the concrete shrinks the bar pulls out slightly.
PS=Ø® also has a small hole on the grout-filled sleeve end of the coupler that creates self-supporting concrete slabs.
This allows for the slab to be fully released from costly formwork and shoring prior to grouting the coupler. No formwork or backshoring needs to be left in place.
Other threaded/grout-filled sleeve couplers have a large hole on the grout-filled end of the coupler that cannot create self-supporting concrete slabs. Consequently, costly formwork and backshoring must be left in place until the coupler is grouted.
Please note: PS=Ø® holds patents on this coupler technology, and the method of connecting rebar to replace a lap splice. Using another system in this manner would be a patent infringement.
Concrete Contractors
Objection: “It seems that PS=Ø® is far more expensive than a traditional pour strip.”
Response:
Most concrete contractors do not estimate the cost of traditional pour strips accurately. When all things are considered—including the project delay when the concrete is curing and before the pour strip can be poured back—it becomes clear that using PS=Ø® is actually less expensive.
Material involved in building a traditional pour strip include:
- Custom formwork
- Plywood that remains in place
- Custom shoring
- Backshoring that cannot be removed until all the building’s pour strips arepoured back, and forms stripped from the top level down
- Two separate bulkheads with holes for rebar that lap in the pour strip
- Custom bridging (often metal plates) to cross over the 4’ to 8’-wide leave-out
- Fall protection and caution tape for safety around the pour strip
Labor involved in building a traditional pour strip:
- Fabrication and installation of custom formwork
- Installation of backshoring
- Fabrication and installation of two custom bulkheads
- Cleaning the leave-out before pouring it back
- Pouring back the small pour strip months later
- Large crews to place and finish
- Removal of custom formwork and backshoring
The labor aspect of this process should not be overlooked. It takes significant labor to build a traditional pour strip. You must consider the time gap in the project while the concrete is curing, as well as the striping of formwork and backshoring. When forming and pouring concrete, it costs a premium for workers to go back and place a pour strip, strip formwork and remove backshoring after the delay.
Less labor is involved with PS=Ø® because no special formwork or backshoring is needed.Typical formwork and shoring can be used and doesn’t need to stay in place. Which means it can be stripped along with all of the other formwork and shoring and workers don’t need to go back after the delay.
Other benefits when using PS=Ø® include:
- Only one bulkhead without holes for lapping rebar
- No special bridging, fall protection, or caution tape is required for safety because there
- is no leave-out
- No labor is required to clean out the leave-out
- No concrete trucks or pumps are required
- No large crews are required to place and finish the pour strip
- Only a small crew is needed to mix grout and fill the PS=Ø® couplers and reliefjoint!
General Contractors
Objection: “I don’t understand how PS=Ø® saves months on construction
schedules.”
Response:
Pour strips require special formwork and backshoring that must stay in place until the leave-out is poured back and formwork and backshoring stripped from the top level down, not bottom level up.
For example, even though lower level pour strips are placed, backshoring at those levels cannot be removed until the upper level pour strips are poured back. Once the upper level pour strips are placed, formwork and backshoring can safely be stripped from the top level down. Backshoring requirements are often overlooked, adding months to construction schedules.
Backshoring is different from reshoring. Reshoring can be safely removed after concrete slabs are self-supporting and no longer needed. Backshoring, on the other hand, cannot be removed at pour strip slabs because they don’t self-support. The load from the slabs above transfers down the building, accumulating higher loads from top to bottom.
The pour strip bay requires backshoring, and often one adjacent bay will be reshored as well. This is because the slab edge of a pour strip located near the column line will deflect vertically if the adjacent bay is not shored.
A traditional pour strip is left open anywhere from 28-120 days. In other words, the pour strip must remain open with backshoring in place until the leave-out is poured back for 1-4 months on each level. If there are multiple levels, this delay starts to compound because backshoring must remain in place until the pour strips on the upper levels are poured back.
When backshoring is present, it will delay the entire construction schedule because other trades will not have access to two bays of the building. Furthermore, it must be stripped from the uppermost level down to the lowest level, and the clock doesn’t begin until after the uppermost pour strip is placed. That is to say, while all the other trades have full access to the entire building, they will not be able to work in two bays from top to bottom. This creates a major impact on schedules. Our historical data confidently shows that PS=Ø® routinely saves 2-4 months on construction schedules. This equates to $100K-$350K per floor, depending on the project type and number of floors.
We would be happy to address any lingering questions or concerns you might have. Contact us today to schedule a meeting, or call us at 800.355.8414. We look forward to talking with you about how PS=Ø® can reduce costs, accelerate construction, and improve safety on your next project!
