Internally Cured Concrete Mixtures and Specifications for Highway Infrastructure
1 online resource (187 pages) : PDF
University of North Carolina at Charlotte
Internal curing is a relatively simple approach to reduce the shrinkage and cracking potential of concrete mixtures, accomplished by placing reservoirs of water within the concrete to provide additional moisture to facilitate hydration of the cement. These reservoirs are supplied by materials that can retain a significant amount of water, such as manufactured lightweight aggregates (LWA) added to the concrete in a prewetted condition. Benefits of internal curing, including reduced early-age cracking, are of particular interest in construction of concrete bridge decks and pavements, as agencies require longer-lasting, more durable highway infrastructure.For this work, bridge deck and pavement concrete mixtures, produced using a variety of materials local to North Carolina, were batched and tested to provide insight into the benefits of internal curing. Two types of prewetted fine LWA were used to replace normalweight fine aggregate in different quantities to evaluate internal curing potential. Tests to evaluate the performance of fresh and hardened concrete were performed.Compared to conventional concrete mixtures, internally cured concrete and mortar mixtures showed significant reductions in restrained drying and autogenous shrinkage (up to 56%). The mechanical properties and durability performance of internally cured mixtures was typically similar to that of conventional mixtures. Of note, internally cured mixtures had, on average, a 20% lower modulus of elasticity than control mixtures, which could further aid in reducing cracking potential. Additionally, the CTE was reduced in all internally cured concrete mixtures (up to 11%) compared to control mixtures, indicating potential for improved thermal performance.As this approach to concrete curing has not yet been used in concrete construction in North Carolina, specification provisions are presented that may be beneficial towards the creation of a Department of Transportation (DOT) specification developed to support successful implementation of internally cured concrete in future highway infrastructure projects.
Construction & Facilities Mgmt
Tempest, BrettNicholas, Thomas
Thesis (M.S.)--University of North Carolina at Charlotte, 2017.
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