Concrete Admixtures - Project Profiles:
Lower North Outfall Sewer

Project: Lower North Outfall Sewer
Location: Los Angeles, CA, USA
Products: Self Consolidating Concrete
Ready Mix producer: CEMEX
Admixtures: Grace Construction Products
Contractor: Colich & Sons/J.R. Pipeline
Owner/Engineer: The City of L.A. Bureau of Engineering

The Challenge . . .

Creativity was needed to reach the underground forms through just three access points. SCC was poured into manholes to waiting pumps, sending the concrete as far as 2,000 feet.

The SCC needed to maintain its flowability through the angular, narrow forms to create solid concrete sections with no voids, bubbles or aggregate pockets.

The Solution . . .

Only a Self-consolidating concrete mix could meet the specs.

With some of the original wood frame still visible, the tunnel was excavated down to the rough aggregate. New 12-inch thick cast-in-place concrete is installed inside the existing tunnel using formwork that left a one-foot space between the forms and the old tunnel surface. The very flowable and low-shrink mix SCC design was achieved using Grace shrinkage reducing admixtures, high-range water reducing superplasticizers, viscosity modifier and hydration stabilizer.