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Sometimes they serve as mounts for a concrete block, which provides further isolation. Pads or sheets of flexible materials such as elastomers, rubber, cork, dense foam and laminate materials. Elastomer pads, dense closed cell foams and laminate materials are often used under heavy machinery, under common household items, in vehicles and even ...
Interest in concrete railway sleepers increased after World War II following advances in the design, quality and production of pre-stressed concrete. Chaired bullhead concrete sleepers have been around since at least the 1940s; the Great Western using a two-holed chair, thus saving both scarce wartime timber and steel fixing bolts. [ 4 ]
A section through Zibold's dew condenser. (a) is a truncated cone of beach pebbles 20 metres (66 ft) in diameter at the base and 8 metres (26 ft) in diameter at the top. (b) is a concrete bowl; a pipe (not shown) leads away from the base of the bowl to a collecting point. (c) is ground level and (d) is the natural limestone base. [11]
Schematic cross section of a pressurized caisson. In geotechnical engineering, a caisson (/ ˈ k eɪ s ən,-s ɒ n /; borrowed from French caisson 'box', from Italian cassone 'large box', an augmentative of cassa) is a watertight retaining structure [1] used, for example, to work on the foundations of a bridge pier, for the construction of a concrete dam, [2] or for the repair of ships.
Elastomeric bearing pads, to serve as bridge beam supports heads. An elastomeric bridge bearing, also known as a pot bearing or elastomeric bearing, is a commonly used modern bridge bearing. The term encompasses several different types of bearings including bearing pads, bridge bearings, laminated elastomeric bearings, and seismic isolators ...
The American Concrete Institute (ACI, formerly National Association of Cement Users or NACU) is a non-profit technical society and standards developing organization. ACI was founded in January 1905 during a convention in Indianapolis.
It is called an "over-under" configuration with the drywell forming a truncated cone on a concrete slab. Below is a cylindrical suppression chamber made of concrete rather than just sheet metal. Both use a lightweight steel or concrete "secondary containment" over the top floor which is kept at a slight negative pressure so that air can be ...
Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]