Author
C S BARBOSA1 and J B HANAI2
1PhD Student, Department of Structural Engineering, University of Sao Paulo at Sao Carlos, Brazil
2Professor of Structural Engineering, Department of Structural Engineering,
University of Sao Paulo at Sao Carlos, Brazil

Abstract
The standard test of hollow concrete blocks assigns the use of flat steel platens for uniform stress distribution. The friction forces between the platens and the unitinduce a confinement effect that increases the real compression strength. The present analysis aims to correlate the standard situation with a condition where the confinement effect is reduced by the use of a brush platen. The brush platen is constituted by thin steel sticks that allow almost free transversal strains at the top and bottom of the blocks.The test results confirmed the reduction of the compressive strength value when compared to the standard test condition. The longitudinal and transversal strains throughout the face-shells and webs and their stress-strain relationships were analyzed. Hollow core blocks and samples were specially prepared with plastic consistency concrete to compare the mechanical properties as measured in different tests.

Key words
Masonry, hollow concrete blocks, compressive strength, confinement effect, mechanical properties, brush platen.