Pullout Test for Hardened Concrete Using Post-Installed Expandable Inserts

The ELE Pullout Test Equipment is an in-situ, semi-destructive method for estimating the compressive strength of hardened concrete. It involves installing an expandable insert into a drilled hole in the concrete, preparing the surrounding concrete by grinding where required, and applying a pullout load and pull the insert out together with a portion of the surrounding concrete.

The ELE Pullout Tester is useful for evaluating the in-place strength of newly constructed or exiting concrete structures.

Test procedure

• Site selection: Select a suitable test location, ensuring adequate clearance from edges, reinforcement, and adjacent test points.
• Drilling: Drill a hole perpendicular to the concrete surface using the specified drilling equipment.
• Cutting and undercutting: Prepare a flat bearing surface and cut an annular groove at the specified depth using a suitable cutting tool.
• Insert installation: Position the expandable insert in the undercut groove and expand it using the designated installation tool.
• Pullout loading: Install the bearing ring and calibrated loading apparatus, then apply a controlled tensile load until the concrete fails around the insert.
• Result assessment: Record the maximum pullout load and inspect the failure cone. Estimate the in-place compressive strength using an experimentally established correlation applicable to the concrete mix and test system.

Advantages

• Enables in-situ strength assessment without installing inserts during concrete casting.
• Provides results that can support decisions on formwork removal, prestressing, construction loading, retrofitting, rehabilitation etc.
• Can be used for both newly constructed and existing concrete structures.