Jiong Hu, Yong-Rak Kim
Alkali silica reactions; Asphalt mixtures; Cracking; Deterioration; Freeze thaw durability; Patching; Pavement distress
Concrete pavement distresses resulting from freeze/thaw (F/T) deterioration, alkali-silica reaction (ASR), and chemical attacks may cause different forms of deterioration, including scaling, cracking, breaking, chipping, and fraying. Concrete pavements exhibiting severe distresses such as transverse cracks, shattered slabs, and corner breaks require patching are commonly observed in concrete pavement in Nebraska. Due to the opening requirement of the pavement to traffic after the placing of repair concrete, it is essential to achieve high early strength. To ensure high early strength, the current patching mix (i.e., PR in the Nebraska Department of Roads [NDOR] specification 1002.02) requires a minimum cement content of 752 or 799pcy for PR1 and PR3 mixes respectively. Besides the high associated cost, the high cement content tends to result in a less stable mix with a high drying shrinkage, high autogenous shrinkage, high heat of hydration and cracking potential. The mixes also exclude the use of fly ash, which makes it vulnerable to various deteriorations, particularly ASR. In order to reduce the material cost and premature failures of pavement repair, patching materials that develops early strength and is durable is needed. This study is to improve the current rapid patching materials. The research team will particularly focus on mix design in terms of aggregate gradation, cement type and content, water-to-cement ratio (w/c), and incorporation of proper chemical admixtures to achieve sufficient early-age strength that is comparable to the current NDOR PR mixes, yet more durable and resist to deteriorations such as ASR.