In response to a shortage of plate steel during the Second World War, the United States Maritime Commission ordered 24 ships and 58 barges to be constructed with lightweight concrete. The ships were typically about 336 ft (110 m) long with a beam of 54 ft (16.5 m) and a displacement of about 11,000 tons (10,000 t). These ships and barges performed various levels of military service but typically for relatively short times due to several factors, not the least of which was the end to hostilities shortly after their launches. The useful service of these vessels (as ships and barges) was measured in months, with some being decommissioned immediately after delivery. However, at Powell River in British Columbia, Canada, as a floating breakwater and impoundment for the log storage pond, most of the surviving hulks have over 50 years of service in a saltwater environment. The Powell River floating breakwater is comprised of seven WWII steam-ships, two WWII barges, and one WWI steamship. The paper mill in Powell River acquired these ships between 1948 and 1966. After their arrival, the ships were stripped of amenities and machinery and the hulks placed in service as a breakwater.
For most of the hulks™ life as a breakwater, they were protected from direct barge impact by the numerous logs floating in the storage pond deï¬ned by the hulks. With the changing operations of the mill and the removal of the logs, the hulks became vulnerable to impact by barges also operating in the pond. This article describes the recent shotcrete repair of the impact damage to some of the hulks.
Need for Repair
While the hulks are showing deterioration related to the corrosion of the reinforcing steel due
The Setenave Dry Docks Rehabilitation
Sentenave is ageneral designation for a shipyard built in the ninty seventies at the right end of Portugal
Silica Fume in Shotcrete
Silica fume is a highly pozzolanic mineral admixture that has been used mainly to improve concrete durability and strength and as portland cement replacement. Silica fume has been used primarily in the United States, Canada, and the Scandinavian countries, but is now finding increasing use elsewhere in the world.
Shotcrete Repair Saves Baltimore Bridges
This Shotcrete Classic was selected for reader interest. While ï¬rst published 23 years ago, most of the dry-mix shotcrete technology described for repair of bridges still remains relevant today. There are a few areas where things have changed. Small line wet-mix shotcrete equipment is now available with suitable start and stop characteristics for small volume wet-mix shotcrete repair of bridges and other structures and is now also widely used for this purpose. Also, with proper surface preparation and the incorporation of silca fume in shotcrete, bonding agents are now seldom used, or needed. Good guidance regarding current recommendations for shotcrete repair of bridges can be found in the AASHTO-AGC-ARTBA Task Force 37 Report œGuide Speciï¬cation for Shotcrete Repair of Highway Bridges, published in 1998 by AASHTO in Washington, DC.
Architectural Finishes for Retaining Walls
What kind of architectural ï¬nishes are possible with shotcrete? From the most basic natural gun ï¬nish to exotic carved sculptures, from the gray color of regular portland cement concrete to custom-colored and stained mixtures, shotcrete can take on many different types of ï¬nished appearance. Today™s designers are continually challenged to provide quality finishes that ï¬t the surroundings; and in many applications, shotcrete can ï¬ll these needs. Cut and Finish Methods Achievement of an architectural ï¬nish starts with the establishment of the ï¬nal surface plane. Perimeter forms and guide wires are used to
Jefferson Street Bridge: The “Million Dollar Bridge” Listed on the National Register of Historic Places
Dubbed the “million dollar bridge” by town residents, referring to the cost of building the structure in 1921, the Jefferson Street Bridge in Fairmount, WV, is a three-span reinforced concrete arch bridge that crosses the Monongahela River. Listed on the National Register of Historic Places, the bridge was originally designed by The Steel Engineering Company of New York and was dedicated to the town of Fairmont on May 20, 1921. The John F. Casey Company of Pittsburgh completed the original construction.
Having been used by Fairmont residents for more than 70 years, the Jefferson Street Bridge needed restoration work to ensure the continued safety of the structure. The goal of the restoration project was to take down 80% of the structure with only the original arches remaining intact, reconstruct the bridge with new materials, and retain the same appearance as the original 1921 design.
In 1998, the Mosites Construction Company of Pittsburgh began the two-year restoration project. Working with architectural ï¬rm Howard Needles Tammen & Bergendoff (HNTB) of Alexandria, VA; engineering ï¬rm Gannett-Fleming of Pittsburgh; and RCS Consulting of Ripley, WV, Mosites Construction Company had to overcome numerous challenges related to the design and location of the bridge. Before any demolition could be done, precautions were taken to protect a communi-cations ï¬ber optic cable that ran under the south sidewalk of the bridge. Also, to preserve the six original arches, special engineering methods were employed to keep the demolition of other areas of the bridge from harming the arches. To duplicate the original appearance of the structure parapet and light poles, special architectural precast forms were designed.
To help restore the piers and arches, Mosites Construction Company turned to The QUIKRETE® Companies for its high-quality commercial-grade products. Using 6400 m2 (69,000 ft2) of 37.5 mm (1.5 in) thick pneumatically applied QUIKRETE® Gunite MS®, Mosites successfully restored all four sides of the existing arches.
Construction and Repair with Wet-Process Sprayed Concrete and Mortar
A technical report has just been published in the UK by the Concrete Society. This new the Department of Civil and Building Engineering at Loughborough University: Simon Austin, professor of structural engineering; Peter Robins, senior lecturer; and Chris Goodier, a former research associate at Loughborough University, now a senior consult-ant with BRE™s Centre for Concrete Construction.
Artistic Shotcrete for a Historic Auditorium
The Goetheanum (Fig. 1) in Dornach, near Basel, Switzerland, was constructed in the late 1920s from a design by Austrian social philosopher and œspiritual scientist Rudolf Steiner. This building represents the first use of reinforced concrete for monumental, sculptured forms.
Shotcrete Lions for Calgary’s Centre Street Bridge
The Goetheanum (Fig. 1) in Dornach, near Basel, Switzerland, was constructed in the late 1920s from a design by Austrian social philosopher and œspiritual scientist Rudolf Steiner. This building represents the first use of reinforced concrete for monumental, sculptured forms.