Height (the distance) are allowed, particularly in concrete walls and columns how?
Allowable height of concreting , particularly in concrete walls and columns how? and what is international codes idea?
Usually, people who believe in the necessity of making limited free space across the concrete are a major reason the possible detachment of the concrete, as.
First of all it must be said in the European concrete code & ACI code and many prestigious international codes, a certain height limits for concrete fall(free fall) have not seen concrete. While at the journal, 55 (technical specifications construction works) and national regulations (the ninth topic) such restrictions and strict type there.
The 20-year research in the city of Chicago which is ended in 80th ad showed that the height of free fall from 10 to 40 meters of concrete, no detachment for the slump more than 10 cm is not created and the concreting of the research mainly in our new (crate) and was done in depth Of different depths and to control the sampling has been done detachment. The result of this research indicates that it was merely the height of free fall is not the factor, but if the detachment operating concrete for there is a detachment, wherein an increase in height can be bolsters detachment.
Concrete vertical body to deal with 90 ° angle or less templates, horizontal and vertical wires to concrete encounter, the horizontal component of the speed of the exit tube in concrete pump and ramp (concrete chute) including the major and important factors are detachment. When the detachment with the help of these factors or one of them occurs by increasing the height of 2.1 meters high, usually to be intensified and that is somehow a detachment in the piece are evident and will be in the pool.
Beside all this content should have said various concrete detachment talent does not equal. The psychological boost, climbing to water ratio, increase the nominal maximum aggregate, coarse grain and texture than a lack of fine particles in sand and concrete and also some other factors to climb a concrete detachment leads a different talent. So there may be factors that cause detachment of the concrete are not a concrete measure to develop detachment because their detachment talent is different.
Since it is more or less a detachment because of factors create the problems and limitations of the Executive there, reducing the height of the free-pouring of concrete, it is better to be placed on the agenda. Also valid on all international regulations it is said that in total shall occur in concrete detachment. So you should take this up to tricks used to reduce the quality of the piece and the resulting concrete structures. For this purpose you must at first, low concrete detachment and talent, while the proper measures, factors create the detachment as possible from the ruined, otherwise free to reduce the height of the concrete plan to witness this phenomenon clearly. In its concrete density of concrete to free fall height of 5 or 6 meters is limited to tiny cavities and reduced concrete surface of the bottom of the template column and wall pumps.
From the journal of the Association of Iran’s concrete, issue 68