We used air-powered external vibrators. Crews were able to adjust the consolidation force by controlling the air valve. Higher force should be used for deeper and thicker walls with more reinforcing and embeds. Additionally, with external vibration, vibrator men are not required to be on top of the wall — access is from the ground up with a ladder or scaffolding.
Since the project included a performance-based concrete specification, as opposed to a prescriptive specification, we had input into the best concrete mix design for the project. Based on specified compressive strengths of 5,000 and 8,000 psi, exposure classes of F0, S0, P0, C0, and expected SF2.0 finish, our budget and schedule were built around a high slump (8-inch +/-1) pea gravel mix. We choose not to use a self-consolidating concrete (SCC) as it would have increased our material and labor costs since SCC mixes require watertight forms.
This well-coordinated combination of psychology and science produced the desired result and provided for a successful finished product that all project participants are proud to call theirs.
Frank Salzano is Manager, Frame Development and Greg Smith is Regional Frame Manager with Ceco Concrete Construction, LLC. Visit Ceco Concrete Construction online at www.cecoconcrete.com.