Search results
Results from the WOW.Com Content Network
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]
For massive concrete structures whose temperature at core will likely exceed 65 °C during the cement setting and hardening and moreover will be immersed under water or exposed to alkali leaching, the only effective solution to avoid, or to minimize, delayed ettringite formation is to eliminate the tricalcium aluminate C 3 A phase in the cement ...
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 ).
Concrete floor of a parking garage being placed Pouring and smoothing out concrete at Palisades Park in Washington, DC Workability is the ability of a fresh (plastic) concrete mix to fill the form/mold properly with the desired work (pouring, pumping, spreading, tamping, vibration) and without reducing the concrete's quality.
An asphalt concrete surface will generally be constructed for high-volume primary highways having an average annual daily traffic load greater than 1,200 vehicles per day. [19] Advantages of asphalt roadways include relatively low noise, relatively low cost compared with other paving methods, and perceived ease of repair.
Because axial fans are designed to blow air straight down at the floor, they can be used in ceiling and roof structures over 100 ft. tall. Because axial destratification fans can achieve destratification with low CFMs, it is imperative that the air leaving the nozzle achieve an air speed at the floor of between 0.2 and 0.5 m/s.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Air entrainment in concrete is the intentional creation of tiny air bubbles in a batch by adding an air entraining agent during mixing. A form of surfactant (a surface-active substance that in the instance reduces the surface tension between water and solids) it allows bubbles of a desired size to form.