Page 20

2015SpringShotcreteEMag

The Durability of Shotcrete— Looking Back at Projects from 30 to 40 Years Ago A how incredibly difficult it can be to tear out. So I decided to revisit a few of those projects andconcrete repairs, nothing could be more relevant.gunite from a bridge or an overpass knows By Ted Sofis nyone who has ever had to remove old crete being a viable and accepted option for When the durability of shotcrete was selected as take a look at them today. the theme for this issue of Shotcrete magazine, There aren’t any secrets or shortcuts for the idea came up to look at some older projects. achieving good results. Surface preparation is I mentioned that there were projects that we did very important. Care has to be taken to remove 20 to 40 years ago that are still holding up well. the deteriorated concrete back to good, sound With questions that engineers ask regarding shot- material. If you gun over bad concrete, you’ll end Fig. 1(a): Dry-process shotcrete repairs on 31st Street Bridge in Pittsburgh, PA, were done in 1973 over bottom two-thirds of this pier. Architectural details were maintained and shotcrete repairs remain Fig. 1(b): This pier on Pittsburgh side of Allegheny River required in good condition 42 years after they were installed extensive repairs and shotcrete also remains in very good condition Fig. 2(a): Arches and parapets of this single-arch bridge in Bridgeville, PA, were badly deteriorated before shotcrete repairs Fig. 2(b): Concrete on both sides of parapets under in 1977. Dowels and reinforcing bars were installed and dry- capstones were badly deteriorated. They were chipped out process shotcrete placed across arches on both sides of bridge then replaced with dry-process shotcrete 38 years ago 18 Shotcrete • Spring 2015


2015SpringShotcreteEMag
To see the actual publication please follow the link above