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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Pre-Wetted Lightweight Coarse Aggregate Reduces Long-Term Deformations of High-Performance Lightweight Concrete
Author(s): M. Lopez, K.E. Kurtis, and L.F. Kahn
Publication: Special Publication
Appears on pages(s): 661-680
Keywords: creep; high-performance concrete; high-strength concrete; internal curing; lightweight; shrinkage
Abstract:By using high-strength/high performance lightweight concrete in prestressed bridge girders, lengths of bridge girders can be extended by 15-20%. To understand the implications of the use of lightweight aggregate on prestressing losses, long-term creep and shrinkage deformations are of special interest. Long-term deformation of three high performance concrete mixtures was measured. The concretes were developed using Type III portland cement, silica fume, Class F fly ash, natural sand, and 12.7-mm MSA coarse aggregates. In each concrete, the coarse aggregate was varied, among normal weight gneissic granite, pre-wetted lightweight expanded slate, or air-dried lightweight expanded slate. Concrete compressive strengths greater than 75.9 MPa at 24 hours were obtained. Loading and drying (at 23 °C and 50% relative humidity) for creep and shrinkage specimens started at 24 hours of age to best replicate conditions at a precast concrete manufacturing yard. When loaded at 24 hours, the long-term deformation of the pre-wetted lightweight aggregate concrete was less than that of the normal weight aggregate mix. The lightweight concrete with the initially dry aggregate exhibited the largest long-term deformation. These results agree with observations in the literature that the water initially stored in the aggregate is released over time and is able to reduce the long-term deformation of the high performance lightweight concrete.
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