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Conversely, cool air falls to the floor as it is heavier than the surrounding warmer air. [citation needed] In a stratified building, temperature differentials of up to 1.5°C per vertical foot is common, and the higher a building's ceiling, the more extreme this temperature differential can be. [2]
On regular hot summer days, the average air temperature dropped by 0.2 °C to 1.2 °C, while surface temperatures were lower by 2.6 °C to 4.9 °C. [21] Results suggest that cool pavements can enhance comfort for pedestrians, with mean radiant temperature reductions between 0.9 °C and 1.3 °C, and physiologically equivalent temperature ...
Concrete roadway in San Jose, California A concrete road in Ewing, New Jersey. Concrete surfaces (specifically, Portland cement concrete) are created using a concrete mix of Portland cement, coarse aggregate, sand, and water. In virtually all modern mixes there will also be various admixtures added to increase workability, reduce the required ...
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]
When concrete is subject to an excessive temperature increase during its setting and hardening as in massive concrete structures from where cement hydration heat cannot easily escape (semi-adiabatic conditions), the temperature gradients and the differential volume changes can also cause the formation of thermal cracks and fissures.
The formwork is commonly built from wooden planks and boards, plastic, or steel. On commercial building sites, plastic and steel are gaining popularity as they save labour. [27] On low-budget or small-scale jobs, for instance when laying a concrete garden path, wooden planks are very common. After the concrete has set the wood may be removed.
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Under floor radiant systems are evaluated for sustainability through the principles of efficiency, entropy, exergy [33] and efficacy. When combined with high-performance buildings, underfloor systems operate with low temperatures in heating and high temperatures in cooling [34] in the ranges found typically in geothermal [35] and solar thermal ...