![]()
C. M. Consulting |
C. M. CONSULTING A Division of Cliff Mansfield Incorporated
LESSONS LEARNED IN RUSSIA
|
Sieve Size (Metric) |
Tolerance Band |
Design % |
20mm |
95-100 |
96 |
15mm |
85-100 |
87 |
10mm |
70-100 |
75 |
05mm |
50-65 |
52 |
2.5mm |
40-65 |
46 |
1.25mm |
34-65 |
40 |
0.63mm |
27-65 |
32 |
0.315mm |
20-40 |
23 |
0.14mm |
14-23 |
16 |
0.021mm |
6-12 |
8 |
Bitumen |
4-6 |
4.8% |
.
Sieve Size (Metric) |
Tolerance Band |
Design % |
20mm |
95-100 |
100 |
15mm |
54-100 |
98 |
10mm |
42-88 |
85 |
05mm |
30-65 |
62 |
2.5mm |
25-65 |
58 |
1.25mm |
18-65 |
45 |
0.63mm |
12-65 |
33 |
0.315mm |
8-40 |
20 |
0.14mm |
5-22 |
12 |
0.021mm |
2-8 |
4 |
Bitumen |
3.5-5.5 |
4.5% |
As you can see, the broadband specification is quite forgiving, and there was no narrow band to my knowledge. Armed with this information, it was time to set the plant up to comply. The StanSteel plant was set-up to pull dry bin samples, so I asked the testing lab personnel for the percentages of material they desired from each bin. To my dismay, I was again told '60% sand, 40% rock'. I asked them how they calibrated the Teltomat AC plant that sits less than 100 yards away from the TM-40. I was told that they started with an arbitrary set of bin pulls, tested the resulting mix, then modified the bin percentages until they achieved the desired results. I believe this to be a poor way to calibrate an asphalt plant. At this juncture, I decided it was time to teach Avtodor's testing staff how to calibrate an AC plant mathematically. I fired up the plant and ran rock through it until everything was warmed up. Next, I adjusted the feeder outputs so the bin pulls stabilized approximately where I thought they should be in order to yield the results Avtodor wanted. I allowed the plant to run until all four hot storage bin high bin indicators were illuminated, then I dead-stopped the plant and pulled a 1,500 gram sample from each bin. Once we were given a sample result from each hot bin, it was a simple matter to blend back together the aggregates to come up with a percentage we needed from each bin. As a result of this effort, our first sample was within 1% of what Avtodor wanted. The base mix they liked was on the "coarse" side of the specs, yet the surface they liked was as "fine as possible". The following are actual test results of their surface mix.
Sieve Size (Metric) |
% Passing |
20mm |
100 |
15mm |
100 |
10mm |
87 |
05mm |
64 |
2.5mm |
60 |
1.25mm |
57 |
0.63mm |
50 |
0.315mm |
38 |
0.14mm |
20 |
0.021mm |
6 |
Bitumen |
4.5% |
I didn't particularly care about their base mix. I could see that it would work for what they were doing, but on the other hand , I was quite concerned about their surface mix. I couldn't see how this mix would stand up to high-volume truck traffic without simply coming apart and rutting. Every road I'd seen in Russia was rutted badly if it was more than a year or so old. After some spirited discussions on this subject, I was informed that, yes, the local official in charge of mix designs agrees that the mix is failing the real-world test of traffic. I was also informed that this issue would be discussed at the next transportation summit in Moscow and was asked if I could give them a recommended mix design. I gave them a representative 'B' mix from Oregon Department of Transportation specifications and was told that they would get back to me -- That was in April! I'm still waiting, and they are paving on with a mix that ensures they will all have work 'til the end of time. Change doesn't come easily in the Motherland. The issue of centralized control was something that constantly hindered the decision-making process in everything from mix designs to how much fuel to keep in the generator over the weekend. All decisions had to come from the main office. On several occasions, I sat in my hotel for days while the laborious process of "ruling" on one of my suggestions would grind slowly onward. I took twenty novels with me to Russia, by the third week I was reduced to reading asphalt plant tech manuals from cover to cover. By the forth week, I was ardently studying Russian because I had little else to do.
Finally, poor mix design and all, we were ready to pave the roads of the Motherland. A batch plant makes mix in -- "batches" ('magine that!). This requires that some sort of receptacle be positioned under the pug mill when the gate opens and gravity works its magic on the batch. On some plants that receptacle is the chute that carries the mix to a drag conveyor and then to holding silo. On our plant, we had hoped to use waiting trucks as that receptacle, since we had no silo. I was soon to learn that this was to be our Achilles Heel. Russian truck drivers are a breed apart. Independent thinking seems to be a concept lost on these stalwart individuals. My problems began as soon as the first truck pulled up under the plant. The plant was running at nearly 120 tons per hour. I signaled the first truck to pull into position. As he did, I looked down and turned the pug gate switch to automatic. When I look up the truck was ready, however the driver was nowhere to be seen. I assumed he simply stepped out of his truck to check out something or to chew the fat with his buddies. Six batches later I discovered error of my assumption. The driver was nowhere to be found. I was beginning to get nervous, the hot bins were filling up and starting to reject material. I signaled for someone to move the offending truck out of the way and get another one in position. I was in for a bit of a surprise. Apparently, no one else was authorized to drive this guy's truck! By this time I'd had enough. I marched out of the control room and climbed into the aforementioned truck, intent on moving the stupid thing myself. Imagine my state of mind when I discovered that the driver had taken the keys with him. Out of options, I was forced to hot-stop the plant and wait for the guy to return -- which he did about ten minutes later. Apparently he'd missed his tea break earlier in the morning and had decided that he should take it while his truck was being loaded. Once I spit out all the nails I'd been chewing on, I calmly asked the trucking foreman if he could see that this incident was not repeated. To my chagrin, he hauled all his drivers off to a tea break so that he could lay out the new rules. Nearly an hour later, I restarted the plant, confident that the incident was behind us. I was wrong! I loaded six trucks without incident. Then, despite the fact that I could see four trucks awaiting hot mix, no one pulled under the plant. I sent the fledgling plant operator out to see if he could get someone to pull under for a load. He returned a few moments later and shrugged. "Tea break" was all he said. I shut the plant down, a frightening thought gnawing at my consciousness: The 'Cold War' didn't phase these Russian patriots, but God help anyone who got between them and a tea break!
Despite all the problems, we did manage to make nearly 3000 tonnes of hot mix during my stay in the Motherland. All in all, I count myself as fortunate to have been given this opportunity, and I find myself confident that Russian construction practices will improve in the near future. I know for a fact that I learned many lessons while there, and I would hope that I left a small seed of America's construction ideals to take root and grow.
Email me-