Determinação experimental da resistência à tração na flexão em paredes construídas com blocos encaixáveis de solo-cimento

Abstract

Earth construction is an ancestral traditional technique. The earth (soil) is used as a raw material for the obtainment of adobe, fibrous or fiberless bricks, hollow bricks having several shapes and, more recently, special rectified bricks turned out in France. Bricks which are not carried to the kiln to be burned are called raw-earth bricks. In the stabilization of the soil, several binders, such as bitumen, animals´ feces, lime, cementand organic resins, are applied. The blocks used in this work, also called interlocked blocks, are made of soil-cement. Its utilization without laying mortar brings in an innovatory way of setting up walls, which differs enormously from the traditional masonry. For this reason, in order to get the official approval for its use, or not, it is necessary to check its stability concerning the forces acting on a wall. With this purpose, this research has intended to determine the tensile strength in flexure in wallssubmitted to horizontal loads, and compare the results so obtained with those presented by the British Standard BS 5628. Its development occurred through the following stages: a historical summary about the use of masonry in the world; inquiry of the references related to masonry and, specially, to its tensile strength; detailed presentation of the construction system studied herein; attainment of characteristic testsof the wall components and elements; flexure tests on mini-walls, aiming at the determination of tensile strength in pure flexure for parallel and perpendicular moments to the horizontal joints; evaluation of the behavior of walls under a horizontal uniformly distributed load; evaluation of the behavior of walls under simple compression with eccentricity; analysis of the rupture of tested mini-walls and walls. Among the results of this work, the following are to be distinguished: determination of the modulus of elasticity and Poissons ratio of the block used; certification that thewalls built with interlocked blocks resist to pure flexure; certification that mini-walls and walls behave as brittle or quasi brittle; after the determination of the modulus of elasticity in the two directions deflected, the conclusion that the mini-walls are orthotropic concerning stiffness and strength. By setting up a relationship between compression strength of standard blocks and prisms with and without mortar, it has been observed that prisms without mortar have resisted 57% of the load of the standard block; prisms with mortar have resisted 60% of the load of the standard block. Miniwalls have shown characteristic strengths of 0.67 MPa and 0.09 MPa for the perpendicular and parallel flexure to the horizontal joint, respectively. The direct tensile strength of isolated blocks has been 0.40 MPa.