Award of Excellence: High-Rise Category
One and Four Longfellow Towers Project
Submitted by Sika Corporation
Equity Residential Properties
Simpson Gumpertz and
P.J. Spillane Company, Inc.
Structural HealthCare Associates/C-Probe
Chelford, Cheshire, England
The prestigious Longfellow complex is located in the heart of downtown Boston on the Charles River. This project focused on two 38-story apartment buildings, constructed between 1970 and 1972. Inspections conducted in 1997 identified numerous areas of spalls due to corrosion of the steel reinforcement. More recently, sealant joints at the sliding glass doors, ac units, and windows were failing and allowing water to leak into the apartments.
In 2001, inspecting engineers carried out a comprehensive investigation to determine the extent of damage and the root cause. Among other things, they determined spalling had increased by 25% since 1996. Exposed column faces, balcony edges, and floor slab edges had the least cover and most spalls. There was chloride contamination, carbonation, and low cover throughout. Wherever the cover was less than 2 in. there was high levels of active corrosion. The goal of the owner and the engineer was to repair the spalled concrete and leaking joints and to provide long-term protection to the building.
A repair program was designed to repair the spalls and leaking joints and protect the building by mitigating active corrosion. A preview was completed to confirm the design met the objectives.
The contractor completed the installation using an organized work plan that was sensitive to the owners scheduling requirements, provided a comprehensive checklist for installation and involved an inspection engineer to confirm compliance with the design documents. Finally, areas of the building were monitored to confirm effectiveness of the repair and protection program. All of this resulted in a repair program that will no doubt provide long-term durability for this owner.