المواضيع الاكثر مشاهده
12:01 ص | Posted by
Eman Seif |
Fresh concrete tests
*Slump test*
1) The
internal surface of the mould is thoroughly cleaned and applied with a light
coat of oil
2) The mould is placed on a smooth, horizontal, rigid
and nonabsorbent surface.
4) Each layer
is tamped 25 times by the rounded end of the tamping rod (Strokes
are distributed evenly over the cross section).
5) After the top layer is rodded, the concrete is struck off the level with a trowel.
6) The mould is removed from the concrete immediately by raising it slowly in the vertical direction.
7) The difference in level between the height of the mould and that of the highest
point of the subsided concrete is measured.
8) This difference in height in mm is the slump of the concrete.
*V-B test*
1)A conventional slump test is performed,
placing the slump cone inside the cylindrical
part of the consistometer
2) The glass disc attached to the swivel arm is turned and placed on the Top of the concrete in the pot.
3) The electrical vibrator is switched on and a stop-watch is started, simultaneously.
4) Vibration is continued till the conical shape of the concrete disappears and the concrete assumes a cylindrical shape.
5) When the concrete fully assumes a cylindrical shape, the stop-watch is switched off immediately. The time is noted. The consistency of the concrete should be expressed in VB-degrees, which is equal to the time in seconds recorded
* Flow table test*
1)the flow table is wetted.
1)the flow table is wetted.
2)The cone is
placed on the flow table and filled with fresh concrete in two layers, each layer 25 times tamp with tamping
rod.
3) The cone is lifted, allowing the concrete
to flow.
4) The flow table is then lifted up several centimeters and then
dropped, causing the concrete flow a little bit further
5) After this the diameter of the concrete is
measured.
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