الفهرس 
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Abstract
The reinforced concrete flat slab system is a widely used structural system. Its formwork is very simple as no beams or DROP panels are used. However, the catastrophic nature of the failure exhibited at the connection between the slab and the column has concerned engineers. This area becomes the most critical area as far as the strength of flat slabs is concerned due to the concentration of high bending moments and shear forces.
During construction of multi-story building with reinforced concrete floor slabs, shoring and reshoring operations are carried out. The construction is started by setting up the shoring on the previously cast floors and then pouring fresh concrete on next floor, during shoring and reshoring process the weight of freshly poured concrete is transferred by shoring into the previously cast floors. This construction load may exceed the design loads and led to early failure of slabs.
One of the common cause of failures of flat-slab structures during construction is insufficient early-age punching shear capacity under relatively high construction loads. Punching shear failure is a local phenomenon which generally occurs in a brittle manner, at concentrated load or column support region. This type of failure is catastrophic because no external, visible signs are shown prior to occurrence of the failure.
Most of the current concrete researches focuses on punching resistance of concrete slabs after reaching its strength (after 28 days). Punching failure may happen during construction due to insufficient concrete compressive strength of premature concrete. So, the main objective of this thesis is to study and investigate the early punching resistance of concrete slabs.
Keywords: Slabs, Early punching capacity, Premature concrete, Early-age, Punching shear behavior, Early strength admixture.