At our last virtual monthly meeting, Mr. Carl Larosche of Wiss, Janney, Elstner Associates presented on his ongoing research regarding concrete interface bond funded by ACI and PCI with additional support from the WJE In-House Research program. Currently, ACI 318-19 and ACI 562-19 design requirements limit the nominal strength of intentionally roughened, unreinforced interfaces to 80 psi. The low nominal strengths of unreinforced interfaces can lead to reinforcement being required which can result in considerable additional time and expense. The research consisted of shear testing of samples from 20 slabs with various unreinforced interface conditions and topping placement conditions. The research findings indicate that the shear strength of unreinforced interfaces may be significantly higher than the 80 psi nominal strength in ACI 318-19 and ACI 562-19. The research also shows that bond strength is not strongly dependent on the amplitude of surface roughness. This research could potentially lead to less conservative designs for toppings on precast elements, partial-depth repairs, and bonded overlays.
At our next virtual monthly meeting, we are happy to host Mr. David Peraza and Dr. James Bailey, both with Exponent, who will be presenting on “Engineering Investigations of Hurricane Damage: Wind versus Water”. Hope to see you there!