1 00:00:08,490 --> 00:00:10,410 - [Narrator] The Texas Department of Transportation 2 00:00:10,410 --> 00:00:13,320 allows the use of reclaimed asphalt pavement, 3 00:00:13,320 --> 00:00:15,870 known as RAP, in pavement surfaces 4 00:00:15,870 --> 00:00:19,530 to conserve natural resources and save costs. 5 00:00:19,530 --> 00:00:22,320 A big unknown has been the contribution of RAP 6 00:00:22,320 --> 00:00:25,200 to pavement and wet weather skid resistance, 7 00:00:25,200 --> 00:00:27,720 which is critical for public safety. 8 00:00:27,720 --> 00:00:31,020 Researchers at the Texas A&M Transportation Institute 9 00:00:31,020 --> 00:00:34,740 have developed guidelines on how to identify good RAP 10 00:00:34,740 --> 00:00:36,570 and use it in a mixed design 11 00:00:36,570 --> 00:00:38,883 that has adequate skid resistance. 12 00:00:40,110 --> 00:00:42,690 - TxDOT needed to know 13 00:00:42,690 --> 00:00:46,500 how this use impacts the skid resistance 14 00:00:46,500 --> 00:00:48,141 of the pavement surface. 15 00:00:48,141 --> 00:00:49,530 - The SAC is the, 16 00:00:49,530 --> 00:00:53,613 the full name is Service Aggregate Classification. 17 00:00:54,450 --> 00:00:57,183 That's in TxDOT, a specification. 18 00:00:58,050 --> 00:01:01,620 They use this to divide the aggregate 19 00:01:01,620 --> 00:01:03,720 into different categories. 20 00:01:03,720 --> 00:01:07,260 SAC A aggregate is more crushed faces, 21 00:01:07,260 --> 00:01:11,340 is not as smooth as like round stones. 22 00:01:11,340 --> 00:01:12,960 So these stones, 23 00:01:12,960 --> 00:01:16,800 usually, we will use high skid-resistant pavement. 24 00:01:16,800 --> 00:01:20,670 SAC B is smoother and more round, 25 00:01:20,670 --> 00:01:22,950 and maybe even more soft. 26 00:01:22,950 --> 00:01:26,760 So, this cannot use directly in the payment 27 00:01:26,760 --> 00:01:29,970 with high traffic volume or high traffic speed 28 00:01:29,970 --> 00:01:33,510 because the skid resistance maybe not that high. 29 00:01:33,510 --> 00:01:35,910 - [Emmanuel] Considering the increased use 30 00:01:35,910 --> 00:01:40,910 of SAC A aggregates in Texas in recent years, 31 00:01:40,920 --> 00:01:43,953 using RAP promotes sustainability. 32 00:01:44,790 --> 00:01:49,790 By reusing aggregates that would help conserve 33 00:01:49,800 --> 00:01:54,800 the limited supply of virgin SAC A aggregates in Texas. 34 00:01:54,990 --> 00:01:59,673 - [Sheng] We fabricated the aggregate ring specimens. 35 00:01:59,673 --> 00:02:04,673 The specimens was arranged like a ring, like a circle shape 36 00:02:04,680 --> 00:02:07,770 and then we can use dynamic friction test 37 00:02:07,770 --> 00:02:11,670 to measure the skid resistance of this aggregate. 38 00:02:11,670 --> 00:02:13,350 Second task. 39 00:02:13,350 --> 00:02:18,350 We identify test sections and connect all the information 40 00:02:19,260 --> 00:02:24,260 like pixel design information, the skid number information, 41 00:02:24,720 --> 00:02:29,400 and then we also measure the skid resistance 42 00:02:29,400 --> 00:02:34,050 and the texture using the Dyna Friction Tester 43 00:02:34,050 --> 00:02:36,420 and the laser equipment. 44 00:02:36,420 --> 00:02:40,170 Also, we duplicate the mixture in the lab 45 00:02:40,170 --> 00:02:42,360 based on the mixer information. 46 00:02:42,360 --> 00:02:45,240 We can make mixture slab in the lab 47 00:02:45,240 --> 00:02:47,700 and also perform all these tests 48 00:02:47,700 --> 00:02:51,600 like the skid resistant tests and the texture test. 49 00:02:51,600 --> 00:02:56,400 For the third task, we designed more than 20 mixtures. 50 00:02:56,400 --> 00:03:00,540 These mixtures have different RAP types, 51 00:03:00,540 --> 00:03:02,520 different RAP percentages 52 00:03:02,520 --> 00:03:05,190 and different aggregate quotations. 53 00:03:05,190 --> 00:03:07,800 Then we evaluate all the aggregates 54 00:03:07,800 --> 00:03:09,690 and all the mixture slabs 55 00:03:09,690 --> 00:03:12,690 in terms of skid resistant and texture. 56 00:03:12,690 --> 00:03:16,050 Based on that, we develop the relationship 57 00:03:16,050 --> 00:03:18,690 between the aggregate and the mixture 58 00:03:18,690 --> 00:03:22,440 and then we propose the thresholds and the criteria. 59 00:03:22,440 --> 00:03:26,700 - Guidelines were developed that would be useful 60 00:03:26,700 --> 00:03:29,583 in identifying good SAC A RAP. 61 00:03:30,420 --> 00:03:34,350 By using RAP, we would promote sustainability 62 00:03:34,350 --> 00:03:38,520 because we would be basically reusing aggregates 63 00:03:38,520 --> 00:03:42,180 and conserve the state's limited supply 64 00:03:42,180 --> 00:03:46,260 of virgin SAC A aggregates. 65 00:03:46,260 --> 00:03:49,620 And, you know, we show ourselves as being a good steward 66 00:03:49,620 --> 00:03:52,380 of the state's natural resources. 67 00:03:52,380 --> 00:03:53,460 - [Narrator] For more information 68 00:03:53,460 --> 00:03:56,070 and to find the publications for this project, 69 00:03:56,070 --> 00:03:58,890 please visit the TxDOT research library 70 00:03:58,890 --> 00:04:00,393 at the link shown below.