Type of Document	Dissertation
Author	Lopez, Mauricio
Author's Email Address	mlopez@ing.puc.cl
URN	etd-11222005-122831
Title	Creep and Shrinkage of High Performance Lightweight Concrete: A Multi-Scale Investigation
Degree	Doctor of Philosophy
Department	Civil and Environmental Engineering
Advisory Committee	Advisor Name Title Kahn, Lawrence F. Committee Co-Chair Kurtis, Kimberly E. Committee Co-Chair Castrodale, Reid W. Committee Member Gokhale, Arun M. Committee Member Lai, James S. Committee Member
Keywords	prestress losses image analysis internal curing cement-based high-strength Lightweight aggregate
Date of Defense	2005-11-04
Availability	unrestricted
Abstract This multi-scale investigation aimed to provide new knowledge and understanding of creep and shrinkage of high performance lightweight concrete (HPLC) by assessing prestress losses in HPLC prestressed members in a large-scale study; by quantifying the effect of the constituent materials and external conditions on creep and shrinkage in a medium-scale study; and by improving the fundamental understanding of creep and shrinkage in a small-scale study. Creep plus shrinkage prestress losses were between two and eight times lower than those estimated for the design standards and approximately 50% of those measured in similar strength normal weight high performance concrete girders. The lower creep and shrinkage exhibited by HPLC was found to be caused by a synergy between the pre-soaked lightweight aggregate and the low water-to-cementitious material ratio matrix. That is, the water contained in the lightweight aggregate contributes to enhance hydration by providing an internal moist curing. The water in the aggregate also contributes to maintain a high internal relative humidity which reduces or eliminates autogenous shrinkage. This higher internal relative humidity also reduces creep by preventing load-induced water migration. Finally, lightweight aggregate exhibits a better elastic compatibility with the paste than normal weight aggregate. This improved elastic matching and the enhanced hydration are believed to reduce peak deformations at the ITZ which further decreases creep and shrinkage.
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