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International Concrete Abstracts Portal

Showing 1-5 of 41 Abstracts search results

Document: 

SP93-39

Date: 

September 1, 1986

Author(s):

H. R. Woodhead

Publication:

Symposium Papers

Volume:

93

Abstract:

The Vesuvius to Crofton ferry plies the waters of the Strait of Georgia between the east coast of Vancouver Island and the west coast of Saltspring Island. At each end a floating pontoon supports the seaward end of the loading ramp. Prior to 1978, the pontoons were constructed of timber and Styrofoam but they had become waterlogged and badly deteriorated. It was therefore decided to replace them with concrete pontoons to utilize the durability of the material. Tenders were called for the design and construction of the pontoons and Dillingham Construction was the successful bidder. The pontoons were built as hollow boxes without a bottom slab. The walls and top were constructed of high quality reinforced concrete and the inside was filled with closed cell polystyrene to provide the necessary flotation. During the design, care was taken to ensure that the resistance to sea water attack and impact loads was maximized. They were fabricated in the graving dock at Dillingham's yard in North Vancouver and towed out to the site. They have now been providing satisfactory service for over seven years with no signs of deterioration. This rather novel project has shown that floating concrete struc-tures can be built economically and require little maintenance.

DOI:

10.14359/6332


Document: 

SP93-25

Date: 

September 1, 1986

Author(s):

F. Mendis

Publication:

Symposium Papers

Volume:

93

Abstract:

Polymer concretes are finding increasing use as bridge deck overlays. They are impermeable, skid resistant, lightweight and develop strong bonds to well prepared bridge decks. The properties of the polymeric binders and aggregates used to form the polymer concrete are important to the success of the polymer concrete overlays. The binders should be strong and yet flexible and low modulus and the aggregates should behard and resistant to polishing and fracturing. Case histories where such overlays were used in major projects are described in detail together with the methods and equipment used in their application.

DOI:

10.14359/6318


Document: 

SP93-14

Date: 

September 1, 1986

Author(s):

J. G. White

Publication:

Symposium Papers

Volume:

93

Abstract:

The paper reviews the history of development of concrete track ties in Canada with particular reference to the special requirements caused by Canadian climate and geography. Information is given on the extensive concrete tie testinq by CM since 1920 and the more recent CP tests since 1974. Details are also provided on the current CN, CP and QNS&L track tie designs. Information is provided on the current 1985 pad and tangent tie tests jointly sponsored by CN, Pandrol and Genstar Costain. Details are provided of the special precautions taken to minimize the risk of alkali/aggregate reaction in concrete ties which includes the pre-qualification of aggregates and the use of a low alkali Type 30 cement. Information is given on the latest methods of economic analysis of concrete ties together with the status report on concrete switch tie development, bridge tie development and the forthcoming AAR/AMTRAK energy saving study on concrete ties. An outline of future developments is also given.

DOI:

10.14359/6307


Document: 

SP93-37

Date: 

September 1, 1986

Author(s):

E. C. Lim

Publication:

Symposium Papers

Volume:

93

Abstract:

With limited land space in urban areas, more and more s tructures are being built underground. The housing of under-ground transport facilities requires the construction of structures such as tunnels and shafts. The progress of such works has often been affected by poor soil conditions and the ingress of water. To overcome problems associataed with the use of poured-in-place concrete in such conditions, an increasing number of projects rely on the use of precast concrete. This paper discusses the role of precast concrete segments in the lining of bored tunnels, the use of prefabricated diaphragm walls for cut-and-cover tunnels and precast concrete elements for immersed tube tunnels. Constructional aspects of the London Underground Piccadilly Line Extension, Toronto Subway, Hong Kong Mass Transit Railway, Ahmed Hamdi Road Tunnel, Suez and the Lyon Metro are discussed. The topics elaborated include the manufacture of precast concrete elements, their delivery to site, erection procedures, grouting, waterproofing and protection of concrete against aggressive environment.

DOI:

10.14359/6330


Document: 

SP93-34

Date: 

September 1, 1986

Author(s):

R. H. Hebden

Publication:

Symposium Papers

Volume:

93

Abstract:

Three segmental precast concrete arch culverts have been constructed for the recently opened Coquihalla Freeway in British Columbia. Buried structures were desired because of climatic conditions and topographic constraints on road align-The arch culverts are 20 m (65.6 ft.) in span, with a rise of 6 m (19.7 ft.) and length of approximately 65 m (213 ft.). The long span was chosen for debris passage and to erect the culvert over the creek without relocation. The span is 2 m (6.56 ft.) greater than the largest known metal arch culvert. Footings were built by the grading contractor while the arch design was underway. Half-arch slab segments of approxi-mately 250 mm thick were cast near Vancouver and shipped to the site. Erection employed a travelling temporary support truss but no staging was required for completion of backfill. The structures were completed in the summer of 1985. Segmental precast arch culverts offered the advantages of low cost for high-fill crossings, avoidance of bridge main-tenance compared to bridges, tolerance of backfill quality and compaction, and long life compared to very long-span plate arches. Longer spans and deeper fill-covers are foreseen as possible in the future.

DOI:

10.14359/6327


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