Materials selection for concrete overlays : the final report Page: 10
xviii, 192 p. : col. ill. ; 28 cm.View a full description of this report.
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but placing it on top of the existing pavement saves construction time and costs, because it is
much easier and more economical to lay it or the surface than to place it on chairs at mid-depth
[11].
An experiment was conducted at Center for Transportation (CTR) at the University of
Texas at Austin to determine the effect of the steel position on its bonding to the concrete [43].
Two types of concrete slabs were cast in the laboratory. The first group consisted of 12 slabs, 12-
in. by 12-in. by 3-in.-thick. Steel bars were laid on the 3-in.-thick base, after the surfaces were
scarified and before placing an overlay. For the second set of slabs, 12 more specimens were cast,
this time placing the steel at mid-depth. All slabs were cured under normal laboratory conditions.
Schematics of both types of specimens are shown in Figure 2.1.
4
2or3in. BCO
r3in. Rebar
3 in. .,, ,l . Sra" lab "',i
6 in -Rebar
Slab
12 in. !11in.
Cross sections
Figure 2.1. Experiment on reinforcement location
The test consisted of pulling the steel bars from the slabs. All bars failed in tension before
they could be pulled out from the slab, showing that its bond strength is higher than the steel
tensile strength, regardless of the position of the bars. From the test, it is inferred that the bars
will not fail in anchorage, even when placed directly on the surface of an existing pavement.
Therefore, the reinforcement steel can be placed directly on the surface, as is shown in Figure 2.2,
saving construction time, labor, and money. Furthermore, the reinforcement placed directly on
top of the substrate helps to restrain the movement of the new concrete slab due to environmental
changes, which in turn, improves the bond between both pavement layers. The steel will restrain
concrete volume changes at the interface most effectively, which will prevent or retard
debonding.10
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Kim, Dong H.; Fowler, David W.; Ferron, Raissa P.; Trevino, Manuel M. & Whitney, David P. Materials selection for concrete overlays : the final report, report, July 2012; Austin, Texas. (https://texashistory.unt.edu/ark:/67531/metapth303706/m1/30/: accessed July 17, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu.; crediting UNT Libraries Government Documents Department.