1 00:00:00,934 --> 00:00:03,601 (air whooshing) 2 00:00:10,184 --> 00:00:12,510 - [Narrator] Hot-mix cold-laid asphalt mixes 3 00:00:12,510 --> 00:00:14,880 are used in maintenance applications 4 00:00:14,880 --> 00:00:18,510 in many TxDOT districts across Texas. 5 00:00:18,510 --> 00:00:21,690 Until now, these mixes were designed and tested 6 00:00:21,690 --> 00:00:25,983 using a Texas Gyratory Compactor, or TGC. 7 00:00:26,850 --> 00:00:29,160 The Texas Department of Transportation 8 00:00:29,160 --> 00:00:32,370 and the Texas A&M Transportation Institute 9 00:00:32,370 --> 00:00:35,340 are looking to phase out the use of the TGC 10 00:00:35,340 --> 00:00:37,680 as well as update and streamline 11 00:00:37,680 --> 00:00:40,740 the hot-mix cold-laid design procedure. 12 00:00:40,740 --> 00:00:43,860 - [Travis] This research was predominantly looking 13 00:00:43,860 --> 00:00:46,560 at switching our hot-mix cold-laid, 14 00:00:46,560 --> 00:00:50,190 which is a maintenance style material, 15 00:00:50,190 --> 00:00:52,680 from being designed on the Texas Gyratory Press 16 00:00:52,680 --> 00:00:55,410 over to the Superpave Gyratory Press. 17 00:00:55,410 --> 00:00:58,530 The TGC, the Texas Gyratory, has been around 18 00:00:58,530 --> 00:01:00,210 since the late thirties. 19 00:01:00,210 --> 00:01:01,590 In the early 2000s, 20 00:01:01,590 --> 00:01:05,040 the Superpave was created based on the TGC, 21 00:01:05,040 --> 00:01:08,400 and so we've had an effort for probably the past 20 years 22 00:01:08,400 --> 00:01:11,640 to try to get all of our mixtures off of the TGC 23 00:01:11,640 --> 00:01:14,217 and use the more automated SGC. 24 00:01:14,217 --> 00:01:18,270 The hot-mix cold-laid is the last key to this puzzle 25 00:01:18,270 --> 00:01:22,470 and 100% getting away from the TGC. 26 00:01:22,470 --> 00:01:25,440 - When you change to Gyratory Compactor 27 00:01:25,440 --> 00:01:28,860 from Texas Gyratory Compactor to Superpave, 28 00:01:28,860 --> 00:01:33,860 and the performance test has to be changed as well. 29 00:01:33,960 --> 00:01:37,140 So we have to find other performance tests 30 00:01:37,140 --> 00:01:39,390 to replace the HVEEM Stability Test. 31 00:01:39,390 --> 00:01:40,770 - [Travis] Typically with hot-mix cold-laid, 32 00:01:40,770 --> 00:01:42,840 you have to run what we call a HVEEM Stabilometer. 33 00:01:42,840 --> 00:01:46,560 And that's a four-inch diameter specimen, which is the TGC. 34 00:01:46,560 --> 00:01:49,950 So when we go to the SGC, which is six-inch across, 35 00:01:49,950 --> 00:01:52,260 what performance test do we run? 36 00:01:52,260 --> 00:01:54,690 And so this was not only can we design it 37 00:01:54,690 --> 00:01:56,190 on a different press, 38 00:01:56,190 --> 00:01:59,280 but what test do we run instead of the HVEEM 39 00:01:59,280 --> 00:02:00,900 since we now have a larger specimen 40 00:02:00,900 --> 00:02:03,750 that wouldn't work with that older device? 41 00:02:03,750 --> 00:02:08,640 - In the lab, we mold compacted tons of samples 42 00:02:08,640 --> 00:02:10,740 in order to come up, you know, 43 00:02:10,740 --> 00:02:13,320 the equivalent number of gyrations 44 00:02:13,320 --> 00:02:15,630 for Superpave Gyratory Compactor, 45 00:02:15,630 --> 00:02:18,000 and to give the similar aspect content 46 00:02:18,000 --> 00:02:21,780 as usually they do through Texas Gyratory Compactor. 47 00:02:21,780 --> 00:02:24,600 Again, we have to ensure the good performance. 48 00:02:24,600 --> 00:02:27,600 That's why we identify the Cantabro Test 49 00:02:27,600 --> 00:02:31,260 and IDEAL RT Test to ensure they are good 50 00:02:31,260 --> 00:02:33,210 and better performance in the field. 51 00:02:33,210 --> 00:02:37,080 - [Travis] So we have a mock specification 52 00:02:37,080 --> 00:02:39,750 and test procedure for the design 53 00:02:39,750 --> 00:02:41,130 on the Superpave Gyratory 54 00:02:41,130 --> 00:02:44,280 and we have the IDEAL RT Test procedure. 55 00:02:44,280 --> 00:02:45,360 I've actually already sent that 56 00:02:45,360 --> 00:02:47,160 to our level two design committee, 57 00:02:47,160 --> 00:02:49,980 so that represents all of the contractors in the state 58 00:02:49,980 --> 00:02:51,540 that do hot-mix designs. 59 00:02:51,540 --> 00:02:55,560 It's gonna be safer, it's gonna be less upkeep. 60 00:02:55,560 --> 00:02:56,880 We're gonna be able to utilize equipment 61 00:02:56,880 --> 00:02:59,880 that we're using on other hot-mix projects. 62 00:02:59,880 --> 00:03:01,320 So really, we're just gonna be able to cut 63 00:03:01,320 --> 00:03:05,523 half of our equipment inventory, from compactors, in half, 64 00:03:06,390 --> 00:03:08,970 and then we're gonna get better, more repeatable results 65 00:03:08,970 --> 00:03:10,380 between individuals. 66 00:03:10,380 --> 00:03:11,640 - [Narrator] For more information 67 00:03:11,640 --> 00:03:14,670 and to find the publications for this project, 68 00:03:14,670 --> 00:03:17,340 please visit the TxDOT Research Library 69 00:03:17,340 --> 00:03:19,083 at the link shown below.