Q: How many bar sizes differential can be accommodated?
A: Any given size sleeve can connect the bar designated or any combination of smaller bars. For example, the #11U-X sleeve can connect, #11, #10, #9, #8, #7, etc. The minimum embedment length for the bars in the sleeve must follow the requirements for the sleeve size, not the bar size.

Q: What is the difference between a Type 1 and Type 2 splice?
A: Type 1 is the old 125% of specified yield minimum. The definition of Type 2 depends on the code being referenced. ACI-318-02 requires 100% of specified ultimate strength which is the same as 150% of specified yield for ASTM A615. UBC-97 and IBC-2000 require Type 2 to meet 160% of specified yield and the ICBO Evaluation Service adds cyclic testing under Acceptance Criteria (AC) 133. The NMB has been reviewed for Type 2 as noted in Evaluation Report ER-5645.

Q: Do I need to specify Type 2?
A: Type 2 splices are only needed if the coupler is deemed to be in a plastic hinge zone in the structural system and the building is in a high seismic zone that requires following provisions of Chapter 21 of the ACI 318 code.

Q: Is the Type 2 NMB Splice-Sleeve® different?
A: No, it’s the same sleeve. The minimum grout strength changes from 9,300-psi for Type 1 (125%) to 11,000-psi for Type 2 (160%).

Q: Do I need to specify different grout for Type 2?
A: No, the only grout approved for use in the NMB Splice-Sleeve® is SS Mortar®. We have designed SS Mortar® to achieve well over 11,000-psi at 28-days when mixed as directed.

Q: Can I use the NMB upside down?
A: Yes, this is called Pre-Grout position. The sleeve is filled (pre-grouted) just before the precast piece above is erected. This is especially good to create blind architectural connections. If you want the option of pumping grout after erecting, you can detail the use of the 14mm PVC tube and seal off the 22mm port.

Q: Do I need to stagger sleeves?
A: No, sleeves are not usually staggered. It is highly impractical to stagger sleeves on either side of a joint. Many tests have been done over 33 years that show staggering is not necessary. Further, you can refer to the ACI Committee 349 “Code Requirements for Nuclear Safety Related Concrete” that gives design criteria for eliminating staggering that normally is required in Chapter 21 of the ACI 318 code.

Q: How close can I space NMB’s?
A: The NMB is treated like it’s the rebar. You must be able to get concrete around it. If the maximum size aggregate is ¾”, then you should maintain at least 1” between sleeves.

Q: How much concrete cover is required over the NMB?
A: The NMB is treated like it’s the main bar. Depending on the exposure, you need to maintain the cover that would have been required over the main bars.

Q: What is the embedment length of a bar and sleeve assembly?
A: The NMB is considered to be part of the bar and its length is part of the embedment length for the situation in question.

Q: Can the NMB connect Epoxy Coated Rebar?
A: Yes and the coating does not have to be removed. The NMB should also be specified as epoxy coated if the bar is coated.

Q: Can the NMB be hot-dip galvanized?
A: No, we recommend you specify epoxy coated sleeves to connect galvanized bars.