Cast-in-Place vs. Post-Installed Anchors

Anchor bolts come in several different configurations, such as 90-degree bent, headed, rods with threads on each end, or fully threaded rods to name a few. Anchor bolts can be made in many grades. shapes and sizes, however, there are two distinct categories of anchor bolts: post-installed anchors and cast-in-place anchors. Although both types essentially perform the same function, the configuration will differ depending on the application. The following information will lay out the differences between the two.

Yipeng supply professional and honest service.

Cast-In-Place Anchors

Cast-in-place anchors are anchor bolts that are cast in wet concrete before the concrete sets. Normally the anchor bolt will be installed in the foundation, which is then filled with wet concrete, only leaving the projecting thread of the anchor bolt exposed. The most common configurations of a cast-in-place anchor are a headed anchor bolt, a 90-degree bent anchor, or a rod with threads on each end with the embedded end having an assembled nut and often an anchor plate to keep the rod from pulling out. Cast-in-place anchors are normally used when large embedment lengths and high tensile strengths are required for a given load.

Post-Installed Anchors

Post-installed anchors are anchor bolts that are installed after the concrete base has been set. A hole is drilled into the concrete and the anchor is then installed into the hole. There are two main types of post-installed anchors: mechanical expansion anchors (MEA) and adhesive anchors.

Mechanical expansion anchors are first placed into the pre-drilled hole. They then expand, bearing against the concrete surface. Wedge anchors are a common type of MEA. MEAs are easy to install, however they have a relatively low tensile strength and are not recommended for use in tension zones where concrete is likely to crack.

Adhesive anchors are anchor bolts that are placed in a pre-drilled hole, which contains an adhesive that dries and bonds to the anchor rod thread as well as the concrete. Adhesive anchors, also known as epoxy anchors, are capable of reaching high bond-stress values in relatively fast cure times. Adhesive anchors are fully threaded rods that can be supplied in many different grades and finishes and can be cut to any length required for a given application.

Contact us to discuss your requirements of anchor bolt installation. Our experienced sales team can help you identify the options that best suit your needs.

IRC R403.1.3.5.3 Support and cover. said:

Reinforcement shall be secured in the proper location in the forms with tie wire or other bar support system to prevent displacement during the concrete placement operation...

Click to expand...

The IBC and ACI have similar restrictions. ACI 301, Specifications for Structural Concrete, state this:

ACI 301-10 5.3.1.3 said:

Before placing concrete in forms, complete the following:...Position and secure in-place expansion joint materials, anchors, and other embedded items.

Click to expand...

I'm not sure of anything in the IRC that specifically prohibits it for anchors, but there's enough other evidence out there that it's a bad practice that I have no problem disallowing it on projects I'm associated with. As EOR, it's my prerogative to enforce rules above and beyond the minimums in the code (I just can't require less).

Also, search on here for wet setting...there are a lot of threads that discuss it.

EDIT: oh yea, I hate post-installed in residential work. 99.% of foundation walls here are CMU, and options for post installed anchors that provide a meaningful uplift connection into CMU (as part of a complete load path) are essentially zero. There just isn't enough room to drill and epoxy while also missing either bond beam rebar or vertical rebar (either of which is required to develop the strength of the anchor because masonry design codes prohibit the use of unreinforced masonry to resist directly applied tension - only flexural tension is permitted to be resisted by mortar alone). And it never gets inspected. I once walked a jobsite and, for the fun of it, reached down and grabbed the anchor in a hold down...and picked it up out of the hole. The contractor almost recovered his shocked look before I turned to face him - he was 'going to do the epoxy later'. yeah, right...

MyCupboard - I do mostly residential now, but I cut my teeth in commercial/industrial, so my expectations make most residential contractors cringe. I don't care, though - reduced need for reliability of a structure is accounted for in design, not by the builders doing bad work. The practices should be similar - the difference is in the embedment of that anchor for higher loads in higher reliability buildings.The IBC and ACI have similar restrictions. ACI 301, Specifications for Structural Concrete, state this:I'm not sure of anything in the IRC that specifically prohibits it for anchors, but there's enough other evidence out there that it's a bad practice that I have no problem disallowing it on projects I'm associated with. As EOR, it's my prerogative to enforce rules above and beyond the minimums in the code (I just can't require less).Also, search on here for wet setting...there are a lot of threads that discuss it.EDIT: oh yea, I hate post-installed in residential work. 99.% of foundation walls here are CMU, and options for post installed anchors that provide a meaningful uplift connection into CMU (as part of a complete load path) are essentially zero. There just isn't enough room to drill and epoxy while also missing either bond beam rebar or vertical rebar (either of which is required to develop the strength of the anchor because masonry design codes prohibit the use of unreinforced masonry to resist directly applied tension - only flexural tension is permitted to be resisted by mortar alone). And it never gets inspected. I once walked a jobsite and, for the fun of it, reached down and grabbed the anchor in a hold down...and picked it up out of the hole. The contractor almost recovered his shocked look before I turned to face him - he was 'going to do the epoxy later'. yeah, right...

For more Anchor Boltinformation, please contact us. We will provide professional answers.