1
00:00:00,000 --> 00:00:02,583
(upbeat music)

2
00:00:07,500 --> 00:00:09,450
- [Narrator] Use of recycled pavements

3
00:00:09,450 --> 00:00:13,140
and shingles in some asphalt
pavement mixed designs is

4
00:00:13,140 --> 00:00:16,260
common practice for
departments of transportation

5
00:00:16,260 --> 00:00:17,325
across the nation.

6
00:00:17,325 --> 00:00:20,430
While this is undoubtedly
better for the environment

7
00:00:20,430 --> 00:00:22,290
and economically wise,

8
00:00:22,290 --> 00:00:25,230
it's important for the Texas
Department of Transportation

9
00:00:25,230 --> 00:00:28,620
to continue improving the
quality of these mixes

10
00:00:28,620 --> 00:00:31,320
in order to reduce cracking and rutting

11
00:00:31,320 --> 00:00:33,120
on the state's highways.

12
00:00:33,120 --> 00:00:36,690
Research at the University
of Texas at El Paso is

13
00:00:36,690 --> 00:00:38,400
looking at current guidelines

14
00:00:38,400 --> 00:00:40,350
to see how they may be adjusted

15
00:00:40,350 --> 00:00:43,920
to create better performing
recycled mixtures.

16
00:00:43,920 --> 00:00:45,450
- This research was aimed

17
00:00:45,450 --> 00:00:48,960
at trying to increase the
performance of our current mixes.

18
00:00:48,960 --> 00:00:52,140
So in our traditional hot mix design,

19
00:00:52,140 --> 00:00:54,270
what we do is we do what
we call volumetrics.

20
00:00:54,270 --> 00:00:56,520
Everything's just density driven.

21
00:00:56,520 --> 00:01:01,410
All of the bidding for projects
is done based on low bid,

22
00:01:01,410 --> 00:01:04,230
so you're not always getting
the performance out of it.

23
00:01:04,230 --> 00:01:06,390
So at the start of this project,

24
00:01:06,390 --> 00:01:08,940
we had what we call RAP and RAS,

25
00:01:08,940 --> 00:01:12,720
so recycled asphalt pavement
and recycled asphalt shingles.

26
00:01:12,720 --> 00:01:15,210
Economically, it seems like
a good choice up front,

27
00:01:15,210 --> 00:01:17,910
because it seems like
free binder, free asphalt,

28
00:01:17,910 --> 00:01:20,490
and we don't always see
the long-term performance.

29
00:01:20,490 --> 00:01:23,880
And so this project was look looking at,

30
00:01:23,880 --> 00:01:26,610
how do we increase the
life of that pavement

31
00:01:26,610 --> 00:01:28,950
while still utilizing these materials?

32
00:01:28,950 --> 00:01:32,640
So we didn't just do
volumetric with density design.

33
00:01:32,640 --> 00:01:34,260
We actually would put in a cracking

34
00:01:34,260 --> 00:01:35,670
and a rutting performance test,

35
00:01:35,670 --> 00:01:37,380
and try to balance the performance

36
00:01:37,380 --> 00:01:39,570
while also balancing economics

37
00:01:39,570 --> 00:01:40,710
and still getting that density.

38
00:01:40,710 --> 00:01:42,650
- Here we are also focusing on rutting,

39
00:01:42,650 --> 00:01:45,690
we are also focusing on the cracking,

40
00:01:45,690 --> 00:01:47,520
so the term balanced mix.

41
00:01:47,520 --> 00:01:49,680
So we are not focused just on rutting,

42
00:01:49,680 --> 00:01:51,450
we're gonna look at cracking,

43
00:01:51,450 --> 00:01:53,880
and we started doing a cracking test,

44
00:01:53,880 --> 00:01:55,680
which was the overlay test.

45
00:01:55,680 --> 00:01:57,660
TxDOT is adapted to the overlay test.

46
00:01:57,660 --> 00:01:58,783
So we worked on that,

47
00:01:58,783 --> 00:02:00,810
and to make it easier,

48
00:02:00,810 --> 00:02:03,450
we developed a couple of tools online.

49
00:02:03,450 --> 00:02:05,610
One of 'em for the cracking test.

50
00:02:05,610 --> 00:02:08,130
Instead of, a lot of people
have different equipments,

51
00:02:08,130 --> 00:02:11,820
and reducing the data,
sometimes you have variation.

52
00:02:11,820 --> 00:02:13,080
We put the online tools,

53
00:02:13,080 --> 00:02:16,080
so anybody can go in with
their raw data, reduce it,

54
00:02:16,080 --> 00:02:18,000
and come up with the same answer.

55
00:02:18,000 --> 00:02:21,255
The other thing we did
is, the mix design itself,

56
00:02:21,255 --> 00:02:23,940
the text that has been using traditionally

57
00:02:23,940 --> 00:02:25,470
is done in Excel,

58
00:02:25,470 --> 00:02:28,680
and as you know, Excel versions
change year after year.

59
00:02:28,680 --> 00:02:30,630
Not only that, it's very cumbersome.

60
00:02:30,630 --> 00:02:33,990
What we wanted to do is add the
balanced mix design to that.

61
00:02:33,990 --> 00:02:35,730
We came up with an online tool

62
00:02:35,730 --> 00:02:36,600
which goes in there

63
00:02:36,600 --> 00:02:39,720
and grabs components
from that Excel sheet,

64
00:02:39,720 --> 00:02:41,250
mainly the gradation,

65
00:02:41,250 --> 00:02:42,810
and we optimize the gradation

66
00:02:42,810 --> 00:02:44,310
that you need for the balanced mix,

67
00:02:44,310 --> 00:02:45,690
and then you save it,

68
00:02:45,690 --> 00:02:48,063
and it puts it back into same Excel sheet

69
00:02:48,063 --> 00:02:49,710
and everybody else could use it.

70
00:02:49,710 --> 00:02:51,870
So we simplified the process.

71
00:02:51,870 --> 00:02:52,890
- From this research,

72
00:02:52,890 --> 00:02:56,933
we actually developed a
special specification, 3074.

73
00:02:58,830 --> 00:03:00,990
From that balanced mix
design specification,

74
00:03:00,990 --> 00:03:04,230
it has performance tests for
cracking and for rutting.

75
00:03:04,230 --> 00:03:08,880
We've since placed two sections
on the NCAT Test Track.

76
00:03:08,880 --> 00:03:12,780
Those have been in cycle
for about four years now.

77
00:03:12,780 --> 00:03:16,500
And then we've also developed a,

78
00:03:16,500 --> 00:03:18,360
what we call interagency contract

79
00:03:18,360 --> 00:03:22,440
with TTI, UT El Paso, and UT Austin,

80
00:03:22,440 --> 00:03:25,800
and we actually placed 34 test
sections across the state.

81
00:03:25,800 --> 00:03:29,100
- So we put over 30 sections out there

82
00:03:29,100 --> 00:03:30,810
that are balanced mix design.

83
00:03:30,810 --> 00:03:33,120
We varied the RAP content.

84
00:03:33,120 --> 00:03:35,340
We varied the rejuvenator.

85
00:03:35,340 --> 00:03:37,530
Some of 'em had no RAP versus RAP.

86
00:03:37,530 --> 00:03:39,100
Hopefully, within a few years,

87
00:03:39,100 --> 00:03:41,730
we continue to monitor those projects

88
00:03:41,730 --> 00:03:45,113
and see how good this balanced
mix design is going to be.

89
00:03:45,113 --> 00:03:47,610
- So through this monitoring,
the idea would be,

90
00:03:47,610 --> 00:03:51,000
we come up with an improved,
special specification

91
00:03:51,000 --> 00:03:52,590
and that would be our new statewide.

92
00:03:52,590 --> 00:03:57,030
And so we currently have
another interagency contract

93
00:03:57,030 --> 00:03:58,620
right now with TTI

94
00:03:58,620 --> 00:04:00,870
and the idea is to
continue to monitor that,

95
00:04:00,870 --> 00:04:03,390
create a new specification,

96
00:04:03,390 --> 00:04:06,180
and then to start implementing
this in some districts.

97
00:04:06,180 --> 00:04:07,410
- [Narrator] For more information

98
00:04:07,410 --> 00:04:10,380
and to find the publications
for this project,

99
00:04:10,380 --> 00:04:12,960
please visit the TxDOT research library

100
00:04:12,960 --> 00:04:14,643
at the link shown below.