Microconcrete of high performance: properties and behavior under combined compression and one-axis bending

ABSTRACT The high-performance microconcrete is a material that has reduced maximum characteristic dimension aggregate and low water / cement ratio (w/c). In order to verify the applicability in structural elements, the behavior of the material and of a pillar executed with high performance microconcrete were studied. As reference, another concrete with the same proportions of materials was studied, only varying the maximum size of the aggregate. The fresh state, mechanical and durability properties of the materials were evaluated. As for the pillars, they were subjected to a project situation of combined compression and one-axis bending. Considering the columns, in order to obtain the horizontal displacements, deformations in the compressed face of the concrete and the strain in the bars, these columns were instrumented by means of strain gages, comparator watches and Linear Variable Differential Transformer (LVDT); The apertures of cracks were also monitored by means of atomic brush marking. As for the properties in the fresh state, mechanical and durability, it was verified that the microconcrete had better performance in relation to the reference concrete that was attributed to the best properties of the interfacial transition zone. The microconcrete column ruptured by crushing concrete from the compressed face in the intermediate region of the column. The conventional concrete column broke in a section above the intermediate one, and the rupture was characterized by the displacement of the concrete in two adjacent shaped faces, suggesting a rupture by oblique combined bending. The results obtained were compared with the results obtained by the software Esbelt 2.1, which considers the modulus of elasticity according to the standard NBR 6118 (ABNT, 2003). At the end, it was possible to observe the best behavior of the microconcrete column in relation to the conventional concrete column, in terms of greater rigidity, suggesting applicability of the microconcrete in structural elements like precasting elements with thin cross-sections.