March 14, 2013
Penetron Chosen to Ensure Waterproofing and Durability for Historic Pennsylvania Railway Tunnel
Technical support from PENETRON provided a waterproofing solution – and a precise concrete mixture – for the recently completed upgrade of the historic Allegheny Tunnel. PENETRON ADMIX met performance goals and kept the project on track.
Originally built in 1904, the Allegheny Tunnel in Gallitzin, Pennsylvania, was known as an engineering marvel and a crucial improvement to the nation’s railroad system. The tunnel allowed freight to be transported from the bustling ports on the Eastern seaboard to the Allegheny Plateau high above the Chesapeake Bay and beyond to Pittsburgh and the growing markets farther west.
The Allegheny Tunnel is the highest and longest tunnel on the original Pennsylvania Railroad system, measuring approximately 3,605 feet in length, at 2,167 feet above sea level. In 1994, the tunnel was one of the first to be expanded to accommodate two parallel tracks and double-stacked container cars below its arches.
Upgrading for more durability
The construction and design team of LRL Construction Co. and Jacobs Associates specified enhanced waterproofing and freeze thaw resistance for the over 100-year old concrete structure. The wider entrance structures of the tunnel were upgraded with a concrete mixture treated with PENETRON ADMIX, a key ingredient to waterproof the tunnel structure.
“PENETRON ADMIX reacts with water and mineral compounds in the concrete to form insoluble, thread-like crystalline structures that seal pores, capillaries and cracks,” explains Christopher Chen, Director of The PENETRON Group. “In addition, the admixture drastically reduces permeability and the effects of freeze/thaw cycles.”
PENETRON ADMIX was pre-blended by the Quikrete Company into their shotcrete mix, mixed with water on-site, and pneumatically applied – along with additional reinforcing – to the interior of the tunnel entrance. The mix design was placed successfully with minimal rebound and met all targeted set times for the project.
“This project is further validation of Penetron’s effectiveness on shotcrete and older existing concrete applications,” notes Chen. “Just as importantly, we are pleased to have provided a successfully implemented solution for the contractor and tunnel owner.”