Materials selection for concrete overlays : the final report Page: 50
xviii, 192 p. : col. ill. ; 28 cm.View a full description of this report.
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In parallel to this development, several extensive studies in Texas have found a major
loss of pavement performance due to spalling that occurs as a consequence of the delay that the
tining operations cause in the placement of the curing compound [54, 56]. When the pavement is
tined, the curing compound is not applied immediately, because the concrete is allowed to take
its initial set so that the surface can be properly tined. During this period there may be a
considerable loss of moisture in the pavement, and consequently, an increase in the incidence of
plastic shrinkage cracking, which in turn, may result in spalling. Studies comparing pavements
constructed with tining and normal carpet drag finish have found that the accident rates are
similar for both surface finishes when the limestone fines had been eliminated. Thus, considering
the unique characteristics of the Laredo District, where rainfall is limited, carpet drag was
specified as the desired finish for the whitetopping overlay.
3.13.2 Condition Survey Results
The existing transverse crack locations on the outside lane were recorded as seen and
measured from the shoulder. Figure 3.14 shows the crack spacing distribution.
The average crack spacing was 7.8 ft., with a standard deviation of 1.6 ft., and a
coefficient of variation of 21.2%. These numbers indicate that, regarding crack spacing, the
section is behaving as designed.
To assess the crack spacing pattern throughout the section, the one-mile stretch of road
was divided into 100-ft.-long stations, and the average crack spacing for each of these stations
was computed. Figure 3.15 illustrates the average crack spacing by station. For the purposes of
the survey, Station number 1 starts at MP 51, at the southernmost end of the whitetopping
section; station 53 ends at MP 52, at the northernmost end of the section.
30 100%
25 80%
20
v. ,60%
1 Frequency
15
" Cumulative %
40%
10
20%
5 i
0 0%
0 2 4 6 8 10 12 14 16 18 20
Crack Spacing (ft)
Figure 3.14. Cracking spacing distribution50
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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/m1/70/: accessed July 17, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu.; crediting UNT Libraries Government Documents Department.