As we know that the centering is removed only by when the arch has attained sufficient strength. It must be lowered slightly 2 days before removing it finally. In this position. the voussoirs try to close in the compress the mortar.
The centering must be removed before constructing any masonry on the top of the arch otherwise a small settlement may be caused in the arch. It will further causes cracks in the masonry in which arch is constructed.
If span is large i.e. more than 8m, then lowering and removal of centering is done by using sand boxes in order to avoid shocks.
The box is filled with the sand and a plate is provided at the top surface. The prop rests on the plate. The box is provided with a hole at the bottom which is closed by a plug while filling the sand and so that it may not come out.
When the centering is to be removed , sand is allowed to leak from the box by slightly loosening the plug. Then the plug is again tightened and the centering is allowed to remain till the arch attains sufficient strength.
As we know that the centering is removed only by when the arch has attained sufficient strength. It must be lowered slightly 2 days before removing it finally. In this position. the voussoirs try to close in the compress the mortar.
The centering must be removed before constructing any masonry on the top of the arch otherwise a small settlement may be caused in the arch. It will further causes cracks in the masonry in which arch is constructed.
If span is large i.e. more than 8m, then lowering and removal of centering is done by using sand boxes in order to avoid shocks.
The box is filled with the sand and a plate is provided at the top surface. The prop rests on the plate. The box is provided with a hole at the bottom which is closed by a plug while filling the sand and so that it may not come out.
When the centering is to be removed , sand is allowed to leak from the box by slightly loosening the plug. Then the plug is again tightened and the centering is allowed to remain till the arch attains sufficient strength.
It is completely removed after 2 to 7 weeks.