Meeting the new anchor standard

Proper anchor selection can speed installation and assure it meets new cracked concrete standards

As the concrete anchor industry adapts to the new ICC-ES AC193 and AC308 cracked concrete standards, contractors are asking questions about installation requirements. Will the new anchor styles be harder to install? Will they cost more per piece? How do you assure building inspectors that anchors meet the new standard?

Jake Olsen, director of product development at Powers Fasteners, Inc., says anchors that meet the cracked concrete standard install in much the sameway as conventional anchors.

Consider installation methods
“Look at the installation instructions. Are the directions straightforward? You want an installation method that’s not too elaborate. Don’t just look at the cost of the anchor itself; look at performance, ease of installation and the level of confidence you have that crews will install them correctly.”

The ICC-ES AC193 and AC308 cracked concrete standards affect many types of post-installed anchors. The standards were created to help assure these anchors won’t fail if a crack – about the width of a business card – develops after the anchor is installed.

“An example of a questionable category is the drop-in anchor. The performance of drop-in anchors can be significantly affected by the installation conditions and the presence of a crack. That is why we expect very few drop-in anchors to be approved for cracked concrete applications. New anchor designs must be developed for this application,” he says.

“Most currently approved adhesive anchors should meet the new AC308 standard, but may need to be used with a special insert instead of a threaded rod,” says Olsen. “These are generically called Christmas tree rods due to their shape. When you pull on them, they create a wedging action inside the hole.”

Some existing mechanical anchors are expected to meet the new ICC-ES AC193 standard. “They must expand smoothly when loaded so if a crack appears sometime after installation, the mechanical anchor still functions by expanding into the extra space. That’s why drop-ins have trouble in cracked concrete tests. They don’t have any additional expansion after they are set,” he says.

Screw anchors, such as the Powers Wedge-Bolt, do not need any additional design work because the bolt cuts threads into the wall of the hole. However, they must be tested and approved as meeting the new standard.

Tighter tolerances for tight fit
“The new anchor styles will require similar installation tolerances to those with which installers are currently familiar. Specifiers, purchasers, supervisors and workers must continue to pay attention when acquiring tools and supplies to install the anchors correctly,” Olsen says.

Olsen offers some tips to help assure proper anchor installation:
1. Use the correct bit size. This is especially important with mechanical anchors. “It’s easy for workers to overuse a bit or to use a bit that is the wrong size. Workers must check the size to assure it matches the requirements of the hole and anchor. Building inspectors often check bit size, so make sure you are using the correct one,” says Olsen.
2. Replace worn bits. How fast a bit wears is a function of the aggregate and the hardness of the concrete. “In some situations, bits are good for 300 holes, but bits may be good for only 50, especially when drilling deep holes in hard concrete. Bits are expensive, but using a worn bit or using the wrong bit size will cost you much more in labor, rework or the costs associated with anchor failure down the road,” he says.
3. Clean the hole properly. This is especially important with adhesive anchors. “Dust in the hole has a significant effect on adhesive performance,” he says.
4. Torque the anchor correctly. “Anchors that are approved with a specific installation torque will require this torque to be applied during installation,” Olsen says. “This will likely require a calibrated torque wrench.”
5. Document the anchors. “Save the box lids and/or purchase records to show the inspector which anchor was used and pull the corresponding ICC-ES evaluation report to show the anchor meets the cracked concrete specification,” says Olsen.

Powers is developing a distinctive mark that will be used on the heads of its anchors to designate that it meets the cracked concrete standard so inspectors can easily see the correct anchor was used.

Published in the September/October 2006 issue of Contractor Tools and Supplies magazine.

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