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ColorGraphics Weather Systems was a computer graphics company that pioneered the use of computer graphics for displaying weather forecasts on local television. [1] Formed in 1979 by Terry Kelly and Richard Daly, it is now part of Weather Central , another of Kelly's companies.
Each white lump marks the top of a deep ground-freezing tap. Cross section of a ground freezing pipe as used in the Big Dig. Ground freezing is a construction technique used in circumstances where soil needs to be stabilized so it will not collapse next to excavations, or to prevent contaminants spilled into soil from being leached away. [1]
The tremie concrete placement method uses a vertical or nearly vertical pipe, through which concrete is placed by gravity feed below water level. [4]The lower end of the pipe is kept immersed in fresh concrete so that concrete rising from the bottom displaces the water above it, thus limiting washing out of the cement content of the fresh concrete at the exposed upper surface.
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If the surface of the concrete pour is insulated from the outside temperatures, the heat of hydration will prevent freezing. The American Concrete Institute (ACI) definition of cold weather placement, ACI 306, [128] is: A period when for more than three successive days the average daily air temperature drops below 40 °F (~ 4.5 °C), and
A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Steel- reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner mud slabs may be used for exterior paving ( see below ).
A pervious concrete street in 2005. Pervious concrete (also called porous concrete, permeable concrete, no fines concrete and porous pavement) is a special type of concrete with a high porosity used for concrete flatwork applications that allows water from precipitation and other sources to pass directly through, thereby reducing the runoff from a site and allowing groundwater recharge.
The rebuilt upper reservoir of the Taum Sauk plant, nearing completion in this photo, is the largest RCC dam in North America. [1]Roller-compacted concrete (RCC) or rolled concrete (rollcrete) is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for portland cement. [2]