السلوك الانشائي للجسور المسلحة من الخرسانة عالية الاداء والمعالجة داخلياً باستخدام مواد فائضة متوفرة محلياً

STRUCTURAL BEHAVIOUR OF HIGH PERFORMANCE REINFORCED CONCRETE BEAMS INTERNALLY CURED WITH LOCAL WASTE MATERIALS

    The bridge girders are one of the important structural parts in the infrastructure system, which require durability to ensure long service life. Using internal curing materials proved to be useful at enhancing the properties of concrete. This work aimed to examine the effect of internal curing using locally available waste materials as a partial replacement of the fine aggregates on the structural behavior of high performance concrete (HPC) girders. Therefore, two internal curing materials were used in this thesis: crushed brick and limestone, in two percentage of replacement (5% and 10%) for each material. Studying the structural behavior of fifteen reinforced concrete beams (1700*150*100) mm that represents the three testing ages (28,90 and 150) days for each material and replacement percentage as well as the mechanical properties of concrete. Utilizing internal curing showed an increase in ultimate loading capacity for the beams, with 11.5% improvement at 28 days for the 5% brick mix and 23.5% for the mix of 10% limestone at 90 days and 12.6% for the 10 lime stone at 150 days of test. Also, improved the compressive strength by 13.6% for the mix of 10% limestone. Furthermore, improvement in splitting tensile strength of the internally cured mixes was noticed up to 14.8% for the internally cured mix of 5% limestone. Toughness of the beams increased, where the beam of 10% limestone at 90 days had the higher toughness of (0.351) MPa which was higher than the reference mix. Despite that, internal curing materials had negative impact on the ductility of the mixes, since the reference beams showed ductility indices (3.3 to 3.6), but all the internally cured beams had ductility index lower than (3). Using internally cured HPC showed good improvement in both structural behavior and mechanical properties of concrete and the late ages showed high ultimate loads capacity which means internal curing enhanced the durability of concrete structure elements.