Behaviour of recycled aggregate concrete under combined compression and shear stresses

Abstract

ABSTRACT:To investigate the behaviour of recycled aggregate concrete (RAC) under combined compression and shear stresses, 75 hollow cylinder specimens prepared with various replacement ratios of recycled coarse aggregate (RCA) were tested with a self-designed loading device. The results showed that the failure pattern was similar for RAC with different replacement ratios of RCA. The ultimate shear stress improved with an increasing axial compression ratio of less than 0.6 and declined after exceeding 0.6. A modified failure criterion for RAC with normal strength under combined compression and shear stresses was proposed. A new procedure to predict the shear strength for RAC beams without stirrups was developed based on the proposed failure criterion, showing a better correlation with the experimental results than the predictions calculated by GB50010, Eurocode 2, fib Model Code 2010 and ACI 318-11. RESUMEN:Comportamiento del hormigón con árido reciclado bajo esfuerzos combinados de compresión y cizallamiento. En este estudio, se ensayaron 75 probetas cilíndricas huecas preparadas con distintos porcentajes de sustitución de árido grueso reciclado (RCA) con una máquina de ensayos auto-diseñada con el fin de investigar la resistencia del hormigón con árido reciclado (RAC) a la acción conjunta de los esfuerzos de compresión y de corte. Según los resultados obtenidos, el patrón de fractura del RAC era similar independientemente del porcentaje de sustitución. La resistencia a cortante aumentó hasta una relación de compresión axial de 0.6 y disminuyó a partir de ese valor. En el artículo se propone modificar el criterio de rotura del RAC de resistencia normal ante la acción conjunta de los esfuerzos antedichos. Se ha desarrollado un nuevo procedimiento para predecir la resistencia al corte de las vigas RAC sin estribos basándose en el criterio de rotura propuesto, consiguiéndose una mejor correlación con los resultados experimentales que en el caso de las predicciones calculadas mediante los métodos GB50010, Eurocode 2, fib Model Code 2010 y ACI 318-11.

Influence of fly ash, glass fibers and wastewater on production of recycled aggregate concrete

“…Moreover, the decrease in the compressive strength of concrete for the combined use of RCA and fly ash was less than their individual use due to the pozzolanic reaction of fly ash with the adhered cement paste of RCA. Some studies (34,35,38,42) portrayed that the incorporation of fly ash to the RAC presented better performance as compared with NAC in terms of sorptivity, Influence of fly ash, glass fibers and wastewater on production of recycled aggregate concrete • 3 chloride ion migration, and water absorption, etc. The addition of glass fibers improved the compressive, split tensile, and flexural strengths of concrete due to the enhanced bridging effect of fibers in concrete (43)(44)(45)(46)(47)(48).…”