1
00:00:00,184 --> 00:00:02,601
(soft music)

2
00:00:07,680 --> 00:00:10,650
- [Narrator] Continuously
reinforced concrete pavement,

3
00:00:10,650 --> 00:00:14,670
or CRCP, is known for
its long-term performance

4
00:00:14,670 --> 00:00:16,710
and cost-effectiveness.

5
00:00:16,710 --> 00:00:20,100
Recently, fixed CRCP sections in Texas

6
00:00:20,100 --> 00:00:22,920
have shown stress points not usually seen,

7
00:00:22,920 --> 00:00:26,310
with segmentation of slabs
at transverse cracks,

8
00:00:26,310 --> 00:00:28,110
under the wheel paths.

9
00:00:28,110 --> 00:00:31,560
It appears that steel placed
at mid depth of the slab,

10
00:00:31,560 --> 00:00:34,168
can increase warping stresses.

11
00:00:34,168 --> 00:00:36,780
The Texas Department of Transportation,

12
00:00:36,780 --> 00:00:38,580
working with Texas Tech Center,

13
00:00:38,580 --> 00:00:41,940
for Multidisciplinary
Research in Transportation,

14
00:00:41,940 --> 00:00:44,100
investigated this type of distress,

15
00:00:44,100 --> 00:00:47,343
and developed steel designs,
to combat the issue.

16
00:00:48,240 --> 00:00:51,028
- TxDOT used to use CRCP

17
00:00:51,028 --> 00:00:54,570
up to 10 inch, 11 inches thickness,

18
00:00:54,570 --> 00:00:57,120
when the traffic was not that heavy.

19
00:00:57,120 --> 00:00:59,520
But now, due to the, I guess,

20
00:00:59,520 --> 00:01:01,710
increase in heavy truck traffic,

21
00:01:01,710 --> 00:01:04,320
TxDOT is using thicker slabs,

22
00:01:04,320 --> 00:01:07,256
in their pavement, up to around 15 inches.

23
00:01:07,256 --> 00:01:10,230
And what we found out in
this research project,

24
00:01:10,230 --> 00:01:14,913
is that when the slab is
say, up to 10 or 11 inches,

25
00:01:15,930 --> 00:01:16,950
it works okay.

26
00:01:16,950 --> 00:01:20,190
Placing the steel at the
middle depth is okay.

27
00:01:20,190 --> 00:01:25,190
However, when the thickness
was, say 12, 13, 14, 15 inches,

28
00:01:28,050 --> 00:01:29,970
placing steel at the middle depth,

29
00:01:29,970 --> 00:01:31,470
there are some problems.

30
00:01:31,470 --> 00:01:33,120
- We like to consider concrete pavement

31
00:01:33,120 --> 00:01:35,970
as a low maintenance type of payment.

32
00:01:35,970 --> 00:01:39,570
And this distress was kind
of eating into that idea.

33
00:01:39,570 --> 00:01:42,630
And so we wanted to have this research,

34
00:01:42,630 --> 00:01:45,570
so that way we could improve already,

35
00:01:45,570 --> 00:01:48,420
or improve more of our
concrete pavement performance

36
00:01:48,420 --> 00:01:49,350
than what we already have.

37
00:01:49,350 --> 00:01:53,490
And so this was kind of the
basis for this research.

38
00:01:53,490 --> 00:01:54,630
- So what we did was,

39
00:01:54,630 --> 00:01:58,080
we actually selected four projects:

40
00:01:58,080 --> 00:02:01,320
one in Dallas District, El Peso,

41
00:02:01,320 --> 00:02:04,470
San Antonio, and Waco districts.

42
00:02:04,470 --> 00:02:08,220
So we installed various gauges
in the concrete and steel,

43
00:02:08,220 --> 00:02:10,530
in those four construction projects.

44
00:02:10,530 --> 00:02:14,820
Then we analyzed the data
to understand the behaviors.

45
00:02:14,820 --> 00:02:16,470
- The bulk of the research

46
00:02:16,470 --> 00:02:20,340
was looking at different
orientations of reinforcing steel,

47
00:02:20,340 --> 00:02:23,700
and monitoring stresses and
strains in the pavement,

48
00:02:23,700 --> 00:02:26,880
as we modified the steel design.

49
00:02:26,880 --> 00:02:28,980
And so that was the bulk of the research,

50
00:02:28,980 --> 00:02:31,860
was done monitoring field trial sections.

51
00:02:31,860 --> 00:02:34,985
- The major finding is
that if we place steel

52
00:02:34,985 --> 00:02:38,010
a little bit higher than the middle depth,

53
00:02:38,010 --> 00:02:41,910
it changes the pavement
behavior substantially,

54
00:02:41,910 --> 00:02:46,632
and then it really
minimizes any distresses.

55
00:02:46,632 --> 00:02:50,494
- Right now we have
drafted a revised standard

56
00:02:50,494 --> 00:02:53,880
for continuous reinforced
concrete payments,

57
00:02:53,880 --> 00:02:58,560
that incorporate the findings
of this research project,

58
00:02:58,560 --> 00:03:01,410
where we are now adjusting the location

59
00:03:01,410 --> 00:03:04,140
of the reinforcing steel within the slab.

60
00:03:04,140 --> 00:03:09,140
And so we're trying to push
some additional research,

61
00:03:09,270 --> 00:03:13,500
to monitor some of our other
concrete pavement sections,

62
00:03:13,500 --> 00:03:16,080
so that way we could get
a better understanding

63
00:03:16,080 --> 00:03:17,460
of those behaviors,

64
00:03:17,460 --> 00:03:21,330
and potentially modify that steel design,

65
00:03:21,330 --> 00:03:22,980
which could lead again,

66
00:03:22,980 --> 00:03:27,000
better performance and
cost savings down the road.

67
00:03:27,000 --> 00:03:28,230
So we're actively trying

68
00:03:28,230 --> 00:03:30,000
to push some additional research

69
00:03:30,000 --> 00:03:32,730
that stems directly from
this research project.

70
00:03:32,730 --> 00:03:33,960
- [Voiceover] For more information,

71
00:03:33,960 --> 00:03:36,930
and to find the publications
for this project,

72
00:03:36,930 --> 00:03:39,510
please visit the TxDOT Research Library,

73
00:03:39,510 --> 00:03:41,193
at the link shown below.