Análisis del efecto tamaño en el comportamiento a flexión y compresión de elementos de hormigón reforzado con fibras plásticas

Abstract

The influence of the size effect on the mechanical properties of concrete is a problem studied throughout several decades of modern scientific history, however, regulations that control this deficiency have not yet been established. This project describes the flexural and compressive behavior of fiber-reinforced concrete, against this effect. For the comparative analysis, simple concrete and reinforced with macro synthetic polypropylene fibers (HRFP) were mainly designed. The dosage required to obtain a compressive strength of 240 kg/square centimeters at 28 days was quantified through the optimal density method and in the case of concrete reinforced with polypropylene fibers, a proportion of 3kg/cubic meter and 6 kg/cubic meter was added to the mix. Prismatic specimens with sizes of 100x100x350 mm, 100x200x650mm and 100x300x950mm and cylindrical specimens of 100x200mm and 150x300mm were made. The prismatic specimens were tested for bending with 4 support points according to the indications established in the ASTM C1609 standard. The cylinders were evaluated following the NTE INEN 1573 standard. The flexural results show that both the maximum resistance reached in the proportionality limit and the residual resistances that depend on the effective fibers decrease as the size of the analyzed specimen increases. It is verified that the compressive strength is also affected by the size effect, observing a decrease in effort when comparing large cylinders with respect to small ones.