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The rate of flow of the ions between the anode and cathode areas, and therefore the rate at which corrosion can occur, is affected by the resistivity of the concrete. [5] To measure the electrical resistivity of the concrete a current is applied to the two outer probes and the potential difference is measured between the two inner probes.
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 ).
For a given drip chamber (when the fluid drips from the hole into the chamber) drop factor means number of drops per ml of the IV fluid. Flow rate can be calculated with the help of the observations from the drip chamber and its drop factor. The unit of flow rate is gtts/min, where gtts means guttae (Latin plural noun meaning “drops”).
The growth rate of stalactites is significantly influenced by supply continuity of Ca 2+ saturated solution and the drip rate. A straw shaped stalactite which has formed under a concrete structure can grow as much as 2 mm per day in length, when the drip rate is approximately 11 minutes between drops. [14]
No record exists of the first calculations of the strength of structural members or the behavior of structural material, but the profession of a structural engineer only really took shape with the Industrial Revolution and the re-invention of concrete (see History of Concrete). The physical sciences underlying structural engineering began to be ...
Degrading concrete has been the focus of many studies and the most obvious sign is calcium-rich leachate seeping from a concrete structure. [5] [6] [7]Calthemite stalactites can form on concrete structures and "artificial caves" lined with concrete (e.g. mines and tunnels) significantly faster than those in limestone, marble or dolomite caves.
In practice, creep during drying is inseparable from shrinkage. The rate of creep increases with the rate of change of pore humidity (i.e., relative vapor pressure in the pores). For small specimen thickness, the creep during drying greatly exceeds the sum of the drying shrinkage at no load and the creep of a loaded sealed specimen (Fig. 1 bottom).
The test is carried out using a metal mould in the shape of a conical frustum known as a slump cone or Abrams cone, that is open at both ends and has attached handles.The tool typically has an internal diameter of 100 millimetres (3.9 in) at the top and of 200 millimetres (7.9 in) at the bottom with a height of 305 millimetres (12.0 in).The cone is placed on a hard non-absorbent surface.