Avaliação experimental do fenômeno de retração em alvenaria de blocos de concreto.
Abstract
The shrinkage phenomenon is the cause of many verified pathological
manifestations in buildings, especially in those with masonry produced with concrete
blocks. The present work has as goal experimentally to evaluate the effect of shrinkage
in masonry of concrete blocks. Studies had been carried through of shrinkage tests with
blocks of different strength and processes of cure and also monitoring deformations of
small walls constructed with each type of block. The walls had its deformations
monitored for a period of one year, having been that the analyses had been formed
taking in account the three first months of age. With the shrinkage tests are expected to
get coefficients that allow the forecast of this effect in walls. From the necessary
knowledge of the shrinkage of the wall it is possible to foresee the possibility of the
appearance of cracks and to determine the necessity of the creation of control joints to
prevent pathology and also to foresee losses of protension in prestressed masonry.
As result of the work was possible to improve the procedure of test of
shrinkage of concrete blocks according to Brazilian normalization. From the tests of
walls it can be suggested values of shrinkage coefficient to be considered in project.
Also it was possible to quantify some relative characteristics to the phenomenon, as the
highest shrinkage observed in blocks produced with low quality control and in walls
executed in recent ages, the impediment of shrinkage in the first row due to restriction
of the support slab, the same order of magnitude for vertical and horizontal unrestricted
shrinkage, among others.