Frequently Asked Questions for Backer Rods

Does Nomaco backer rod conform to ASTM C1330?

Yes. This is the current specification for backer rod use with wet applied chemical curing sealant. SOF® ROD and Dual Rod® are Type B, HBR® & Green Rod® are type C, Foam Pak II is Type O.

What is ASTM D1056?

ASTM D1056 is a specification for Flexible Cellular Materials, Sponge or Expanded Rubber. This is an old spec used by specifying engineers for backer rod that don’t have current sealant backer material specification such as ASTM C1330 for buildings or ASTM D5249 for pavements. These specifying engineering firms should view our current literature.

What is ASTM D5249 and does Nomaco backer rod meet this specification?

ASTM D5249 is the current specification for backer material for use with cold and hot applied joint sealant in Portland-Cement-Concrete and Asphalt joints. Nomaco Inc. backer rod meets the following ASTM D 5249 classification: Type 1- HBR® XL; Type 3- SOF® ROD, HBR®, Green Rod®, Dual Rod®.

Do you have a MSDS for Backer Rod?

Yes.Click here to view the available MSDS.

Will Nomaco Backer rod absorb moisture?

All backer rods absorb moisture. ASTM C1083 is referred in ASTM D5249 as the test method for water absorption of the Backer materials used in pavement joint reservoirs. ASTM D 5249 Physical Property Requirement Table 1 limits water absorption to .5% by volume, max. ASTM C 1330 Standard Specification for Cylindrical Sealant Backing for Use with Cold Liquid- Applied Sealants; Table 1, Sealant Backer Properties reference ASTM C 1016 procedure B as test method. Various type backer materials have various water absorption levels and meet ASTM C 1330. Users are advised to get Nomaco or sealant manufacturers’ approval for project specific combinations of backer rod and sealant.

What size backer rod would I use for a specific joint size?

Backer rod should be 25% wider than the joint width opening for joints less than 1”. For varying joint openings over 1” width the backer rod should be on the order of 1/4” to 3/4” larger than the reservoir width. Joint reservoirs should be deep enough to accommodate the backer rod, the proper sealant shape factor (width to depth ratio) and any other recess in the joint as specified by the architect or sealant manufacturer.

What happens if I cut the backer rod and exposed the damaged cells to the sealant?

Outgassing can occur, depending on the type of backer rod used. Outgassing appears as bubbles in the sealant which may shorten its service life. Contractors get call backs for bubbles in the cured sealant because the closed cell backer rod is ruptured during insertion into the joint reservoir. Usually this condition causes the gas from within the ruptured cells to create bubbles in the soft uncured sealant. To avoid this condition SOF® ROD or Dual Rod® is specified. Unlike closed cell backer rod Dual Rod® and SOF® ROD are non gassing if ruptured by the contractor during placement into the joint opening.

What will happen if the backer rod is punctured?

Contractors are concerned with punctured closed cell backer rod because out gassing of the backer rod can occur. This will appear as bubbles in the sealant which may shorten the service life of the sealant. Contractors get call backs for bubbles in the cured sealant when the closed cell backer rod is ruptured during insertion into the joint reservoir. Usually this condition causes the gas from within the ruptured cells to create bubbles in the soft uncured sealant. To avoid this condition SOF® ROD or Dual Rod® is specified.

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