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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.
Showing 1-5 of 13 Abstracts search results
Document:
SP218
Date:
February 1, 2004
Author(s):
Editors: John Ries and Thomas Holm
Publication:
Symposium Papers
Volume:
218
Abstract:
SP-218 This is a compilation of papers addressing “High-Performance Structural Lightweight Concrete” presented October 30, 2002 at the American Concrete Institute Fall Convention in Phoenix, Arizona. This symposium was sponsored by ACI Committee 213, Lightweight Aggregate and Concrete, to report on a wide range of global construction applications incorporating high-performance lightweight-aggregate concrete. This diverse symposium included papers that covered microstructural issues (autogenous shrinkage, internal curing), material and structural properties (transfer length, shear strength, seismic behavior), and applications in large civil structures (long-span balanced cantilever bridges, offshore platform, float-in navigational locks).
DOI:
10.14359/14032
SP218-08
T. A. Hammer, 0. Bjontegaard, and E. J. Sellevold
The 3 main factors determining the efficiency of lightweight aggregate (LWA) as internal curing agents in concrete are discussed with reference to published papers: I) total amount of water in LWA, 2) LWA particle spacing factor and 3) the LWA pore structure. A desorption method is suggested to characterize factor 3) directly as the ability of the LWA to release water. The method is applied to two LWA types and the results demonstrate clear differences. The role of water in ordinary aggregates is discussed with reference to autogenous shrinkage measurements in concrete and the equivalent paste. It is concluded that the aggregate with 0.8% water absorption indeed serves as internal curing agent by reducing and delaying the autogenous shrinkage. Finally, it is shown that sealed curing does reduce and delay both the cement and pozzolanic reactions.
10.14359/13059
SP218-09
M. R. Geiker, D. P. Bentz, and O. M. Jensen
The use of internal curing is a highly effective means of mitigating autogenous shrinkage in cement mortars (w/cm=0.35, 8 % silica fume). Two different sources of internal water supply are compared: 1) replacement of a portion of the sand by partially saturated lightweight fine aggregate and 2) the addition of superabsorbent polymer particles (SAP). At equal water addition rates, the SAP system is seen to be more efficient in reducing autogenous shrinkage at later ages, most likely due to a more homogeneous distribution of the extra curing water within the three-dimensional mortar microstructure. A comparison of the water distribution in the different systems, based on computer modeling and direct observation of two-dimensional cross sections, is given.
10.14359/13060
SP218-06
G. S. Sylva, N. H. Burns, and J. E. Breen
The Texas Department of Transportation sponsored Project 0-1852 at The University of Texas at Austin to determine the feasibility of using high-performance lightweight concrete in composite bridge girders and precast concrete deck panels. The scope of the research project included lightweight concrete mixture design development; full scale testing of TxDOT Type A (AASHTO Type I) girders with composite decks; an analytical design comparison of normal and lightweight concrete girders with various deck combinations; and an economic analysis. The purpose of this paper is to highlight some of the findings of this research to give engineers and designers a better understanding of high-performance lightweight concrete and its use in composite bridge systems. Some of the potential advantages of using lightweight concrete include lower loads on the substructure and foundation, lower crane capacities, increase in live load capacity, and lower shipping costs. However, lightweight concrete has unique features that must be considered during the design phase to insure a successful project. Some of these considerations include higher material costs and the higher elastic shortening losses that will result due to a lower modulus of elasticity.
10.14359/13056
SP218-07
C. L. Tasillo, B. D. Neeley, and A. A. Bombich
In initiating the final phase of modernizing the locks and dams on the Monongahela River, the U.S. Army Corps of Engineers, Pittsburgh District, used float-in and in-the-wet technology to build the new Braddock dam. This is the first use of such technology for an inland navigation project in the United States, and was employed to eliminate the cost and construction time associated with a conventional cofferdam for mass concrete construction. The new Braddock dam design was fabricated as two large, hollow-core segments. Unlike such applications used for offshore structures, the inland application was limited by navigational draft, and lock and bridge clearances. This restricted the overall dimensions and mass of the segments. The use of lightweight concrete in a significant portion of the two large dam segments was central to the success of the design. Good planning, an understanding of the concrete materials, and quality control were critical to project success.
10.14359/13057
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