MAINTENANCE AND REPAIR OF EARLY CRACKING IN AIRFIELD APRON RIGID PAVEMENTS

Cement concrete pavement expands and contracts with variations in temperature during the service time. Concrete shrinks as it cures. Concrete slabs curl and warp from temperature gradients from the top to the bottomof the slab. These natural responses cause concrete pavement to crack at fairly regular intervals. The weather almost always has a role in the occurrence of uncontrolled cracking. Air temperature, wind, relativehumidity, and sunlight all influence concrete hydration process and shrinkage. These factors may heat or cool concrete or draw moisture from exposed concrete surfaces. The sub base can be a heat sink that drawsenergy from the concrete in cold weather, or a heat source that adds heat to the bottom of the slab during hot, sunny weather. The new apron at international Najaf airport which constructed in July to November 2016 wasadopted as case study. The cores have been taken from concrete slab normal to contraction (transverse) early cracks have been noticed to investigation the causes of early cracking. The main cause of earlytransverse cracks is the improperly dowel bar construction and the time of sawing is late after the concrete placement.

کلیدواژه ها:

Apron ، Contraction joint ، Dowel bar ، Shrinkage cracking