Hey Gang, So I vowed this would never happen on my watch,and as luck would have it, I was on a plane headed East when it did. I'd like to think things would have turned out different if I was there but... oh well... The truck had 10 yards of concrete on it when it stopped running, the driver cranked and cranked and wasted allot of time before he called in. When help arrived they spent more time trying to get it running. Finally they tried hooking jumper hoses to another truck, but by then there was no killing the load. Turns out the fuel pump stopped making pressure. Not sure if we will try chipping it out.
Chipping it out? 10 yds of readymix? You ain't gonna put me in that hole.
You need to follow the Mythbusters Golden Rule: "If in doubt...C4
ouch....
I have done quite a few over the years.If you have a good demo man it can save a lot of work.We used to put a large window fan over the hopper to keep the air flowing by drawing it in through the inspection hatch in the drum.It was a rainy day job for us and sometimes could take months to complete. Once in a while a poorly executed shot would open up a seam on the drum but that can be fixed.We always tried to be careful about denting the drum with hammers or whatever because that produced points of accelerated wear after it went back in service. I am sure sucking up that dust is one of the reasons that I cannot breathe well today.Ron G
Just call Mcnellis and get a new drum, your gonna spend more in labor and time getting 10 yards of concreet out, than the price of a new drum!
Yeah, I am definately not getting in there, our normal chipper guy said $4500. The drum is only a year old, so some thought is going towards saving it. We'll see what happens, it is out of my hands. Oh, I heard that when the jumpers got hooked up, and it made it's first revolution, the drive tires on one side lifted in the air! I've almost tipped a stalled one over in an intersection getting it started, and I was being really careful. I swear I saw a steer lift up but I would think if the drives go it's over!
A long, long time ago, I worked for a small time concrete contractor that owned two mixers himself. One had a pony motor (Ford 289), to run the mixer. The same thing happened one day when that pony motor quit. Fortunately, this happened while he was still at the batch plant, and they were able to turn the drum partway and hose some of the load out through the access hatch. It still ended up with a good few yards stuck in it. Yeah, even though I had nothing to do with it, I had my day in the barrell on that one. For 10 yards, I'd be seriously thinking about a new drum... On edit: As I hit the post button, it occurred to me to ask how old the drum is to begin with. I guess that answers that question. What does a new drum cost?
To bad to hear that. I bet the new protcol for stalled trucks is send out a jumper truck to get barrell rolling again . Good Luck with it.
Um just wondering whats a new drum cost?
Out here I've seen a lot of drums that look like there made from fiberglass or CF. I bet there no jackhammering those!
Bit late - but I have been told to throw sugar in to slow cement from harding in drum- I have never done it.
Ok i'm from Cali born and raised. I also been around mixers all my life and i have never seen one made out of fiberglass or carbonfiber. Besides carbonfiber costs way more than regular steel.
Vietnam solution: Find two Marines with pump shotguns and buckshot. Find eight to ten convicted felons. (Volunteers) Set Marines to stand watch over felons. Equip felons with one air compressor, two long air hoses, two 80 pound jackhammers and two 60 pound jackhammers. Mix felons and jackhammers inside mixer. Cook in normal daytime temps up to 120 degrees. Allow felons one hour for lunch and rest. Otherwise work felons twelve hours This recipe may take several days to finish.
The sugar will retard the set but it has to be mixed into the concrete to work,at least that is my understanding of it.I have not used it or seen it used,only hearsay.Ron G
Would be nice if we used the Vietnam solution here in the states!
Tonka I have seen the new style drums, and they look similar to fiberglass, but apparently with some exotic materials. They say there is enough weight savings to get another half yard of crete in it. I don't know about that, as I did not think the steel ones were THAT heavy. After I wrote that, I looked it up, and they are composite, with HDPE in it. Found out about one with 50,000 yards hauled, and they measured it at only 30% worn. Article said thet steel is usually nearly finished by that time. They are out here though. I found this info http://trailer-bodybuilders.com/mag/trucks_mcneilus_bets_composite/ As far as cleaning the old one, I like SurferJoe's method best. I have done it before, and it is no fun.
You are correct Ron, the sugar must be blended with the load to be effective. The union I belonged to had two concrete companies signed and I worked with some of the drivers at a freight company and they told me of this method. The drum must still be working for the sugar to work.
That is what I like about the Drum Jumper. http://www.drumjumper.com/ You can just send out a guy in a pickup which is normally much quicker and easier than another truck. If I was still in the RM business I would either buy one or rig one up myself.
All the new ones here are composite. Lighter and wears longer. They kinda look goofy, they are dimpled on the outside kinda like an orange.
I know this is probably a really dumb question but why aren't drums made in two pieces- speparated along their length? The halves could be flanged and bolted and popped apart like a mold when this happens.
Not quite that easy, the drums have fins inside that are what mix then move the concrete out of the drum. These fins are a spiral and they are now embedded in the concrete you can see them in the picture.
Oh. To save face, have the fins bolted through the drum. Undo the bolts and leave the fins in the hardened concrete. (I'll quit now...)
Uh...Rob...how are you going to get the bolts to move that are under the concrete? And being that they are protruding through a round barrel, you would not be able to lift in any one direction to get them to release.
Aren't things like the first and second stages of a rocket held together with "explosive bolts"? Maybe we could use those? (Just helping Rob in his attempt to save face.) But seriously, you could put a flange on the fins and run the bolts into that flange through the sides of the drum. The fins could just stay with whichever side of the drum had the most concrete...
Knowing my luck, the drum would die with the split at straight up 12:00 and 6:00 with mix getting hard equally in both halves. :Banghead
You can also use 6+ 2 liter bottles of coke to dump in to a load to save the drum. Several of the wrecker company's around here Keep 15+ lbs of sugar in all of their HD wreckers and I know 2 that keep 50Lb sacks in their emergency response vehicles. A couple of company's around here tried the composite drums but they were not deemed cost effective. Most of the transit mixer frames are re chassis'ed 3+ times before their sent out for scrap.
Unfortunately your best bet is throw it away and get a new drum. The "Myth Buster" guys are right. C4 will fix anything and everything or make it go away forever.
a mixer full of mud: LOL... I'm going to help Ron save face, by using the "deflection" technique... (Me) I have actually heard of this, but didn't pay it much mind... and there's an old drum laying off the side of the road, up by Hardin... probably what happened to it. Any way... some questions: How long, on average, does it take to set up, after the water is added? And, what happens if you just keep turning the drum after it's starting to set up?... does the mix just "dry up", and resemble a load of sand and gravel... or, can you even keep the drum turning? OCR
I don't know the answer to either question.The chemical reaction that makes concrete "hard" is started when you introduce water to the dry cement.One of the by products of that process is heat and controlling that heat is very important to the quality of the finished product,that is to say the strength in PSI of the concrete in place. That is why the concrete has to be placed above a minimum temperature because if the heat is allowed to flash off too quickly the concrete cannot go through the curing cycle to harden properly. I have seen concrete set too fast,or faster than was anticipated due to several factors,being in the mixer too long for one or just turning in the drum while exposed to the hot sunlight.You can contaminate a load of concrete by allowing some of the previous load to remain in the drum and adding to it for the next delivery.The left over concrete will accelerate the set of the next load considerably. I don't know of any instance where a load was allowed to mix indefinatly so cannot speculate on the outcome but there always seems to be a residue in the drums after being in service for a while,some of which can be attributes to a dry batch plant I would guess and probably some due to carelessness on the operators part.I used to leave my drum turning even when empty on the return trip to the batch plant to prevent that accumulation but this was with the hydraulic mixers,the old gas engine mixers were shut down to save gas.Ron G
I think a bolt together drum would have to be made out of much heavier material
Cure time depends on a lot of things. Outside aire temperature, how much chemical is added if weather is getting colder, hot or cold water, etc etc etc.
The chemistry of concrete is an art/science all to itself. There really is a whole lot more involved with it than adding some water to some cement. It's something I don't know nearly as much about as I'd like to. Wow. Great question. (No, seriously.) I imagine that you'd get much of the load stuck to the inside of the drum, but all the way around, rather than concentrated at the "bottom", with some in granular form toward the center. (Think of "gunite" or "shotcrete", which can be applied vertically, with no formwork.) The centrifugal force of the spinning drum, and the mass of the load itself, would hold the mix to the wall as it hardened, and it would harden from the outside in. Toward the center, it would have less unhardend mix to press it toward the outside, so it would be more likely to dry in a loose, granular form. (Note that I said I "imagine" that, cause I really don't know...)
As long as the drum is turning and you have a adequate supply of water you can pretty much keep concrete in a liquid form. Once it starts down the chute it's a different story, if the concrete has been mixed enough you will have just enough time to get it out of the truck and that's it. If a truck is having problems that are keeping it immobile but the drum is still turning they do make retarding agents that help. The concrete company that I used to work for had a bridge job that was about an hour away from the closest batch plant, they set up a tower with a pipe that injected liquid nitrogen into the load to keep it cool long enough to get to the job. If that hadn't been done then they would not have been able to pour the job. If a load has sugar in it, it will never cure completely, it will go from liquid to a more solid form but it will never get completely hard(you'll still be able to dig holes in it with the heel of your boot). I don't think that weight savings of a composite drum will help you fit more concrete into a drum. I think it will make it so it's legal to carry more down the interstate and other limited load roads. I think that the bolt in fins might be a good point, after all the hatches on the drums are all bolted on and they come off pretty easily. There will always be some residue in the drums no matter how careful you are about flushing at night, most of that will be right in the corner where the fins and the body of the drum come together. You can reduce that to a minimum by taking your time and doing a good job when you flush.(we cleaned our trucks at night by backing under a pipe and putting probably 200 gallons of water into our drums, then agitate that back in forth in the drum and finally dump it out, then we'd cycle the water in our water tanks through the drum until the water came out clear.)
Eh??????????
There's the physical size of the drum, which is how much concrete will fit before it begins to spill out, and there's the weight capacity of the truck. Let's not confuse apples with oranges. I guess the discussion needs to have more specific parameters then. I think an umlimited supply of water might keep a load from sticking to the drum, but it wouldn't be "concrete in a liquid form", as much as it would be a truckload of wet, sandy, cementy gravel. The hardening process will take place once water is added to the cement, whether it's in motion or not. Again, I don't know that, which is what makes it an interesting question. On edit: I'll add, on the subject of how much will "fit" in a drum, an anecdote--When I was working for the concrete contractor I mentioned above, a driver (now that I think of it, it was the same one who had the load get stuck in the truck), added waaay too much water at the plant. Going up a steep hill, he had about 1/2 yard spill right out of the truck onto the street. Yeah, I had to go clean that mess up too...
Digger, Yes the curing process does start as soon as water and cement mix, but as long as you keep it agitated it will stay concrete, and it will stay liquid. Even if it's not agitated and the load isn't very hot it can be recovered and it does not separate. To give you an idea of this, I drove to a site(45mins), while backing in I backed off the edge of the driveway and my truck got stuck(at enough of an angle that we couldn't turn the drum due to fear of a rollover). Waited on a wrecker to show up(a hour easy just for him to get there). We hooked up to the wrecker and tried to get the truck out.(call this another 15-20 mins.) In this process we pulled the tree we were using as a dead man out of the ground and on top of the cab of the truck(another half an hour wasted due to having to go get a saw and cut this tree off the truck.) We then had to move the wrecker and reconnect the to the truck and pull it out.(another half hour). Once this was done I was still able to back up to the pump add water and pour off this load of concrete. When you add water to concrete and if you add enough it will become the consistency of soup and it will loose some strength and it'll look terrible coming down the chute but it's still concrete, it will be grey when it cures and it will still do the job.
Cretebaby, I was replying to this post here: On edit: This was quoted from post number 17 of this thread.
Again, I don't know nearly as much on the subject as I'd like to, but I can't see that. Think in terms of a "slurpee" (or whatever other name for a frozen slush type drink you're familiar with.) It's water, well below the point at which it turns to ice, but kept agitated. It's not hard like ice, but it's clearly not water either. I'm thinking that the behavior of concrete would be something similar. If you were local, I'd say that was one of my jobs, LOL! The driver wanted to be helpful, and said. "Let me take another cut and I can get the chute 6" closer." He got his rears into the soft edge of the hill. Eight hours later, they got him off of there. (Happily for me, I wasn't there for that adventure. I heard about it later from the customer.) But anyway, you're still only taking about 3 hours or so. I'm sure there's a point at which chemistry will no longer be put off, and you're going to end up with wet, but cured, pebbles. I suspect that point might arrive pretty sudenly when it does happen, dependent on factors like temperature and the mix. It would be interesting to hear from somebody who's been educated in all this. I'd never heard the thing about sugar before either.
WOW learn something new everyday, thanks or the info!:drinkup
Glad to help. Your question made me research it since I had seen some of the funny looking drums, but did not really know what they were. It was educational for both of us it seems.
a mixer full of mud: Here's a couple links I scrounged up... Of course, from the old standby, Wikipedia... This one is rather lengthy, so I scrolled through rather fast, and didn't take much time reading... http://en.wikipedia.org/wiki/Concrete This one's not too bad... http://en.wikipedia.org/wiki/Concrete_curing This one has some good pictures of mixer trucks... http://en.wikipedia.org/wiki/Concrete_mixer And this one is a Wiki link, to an off site source... looks fairly interesting... click the home page if you'd like to view the whole site... http://www.understanding-cement.com/hydration.html OCR
Wow! Good Stuff! You guys seem to have handled every question that came up. Mud Maker, thanks for the link to the jumper, They are actually considering having me build one! My company tried some of the composite drums once. For a few months they were awesome, then one day a Fin Fish ( an oddly fish shaped chunk of concrete) broke free and punched several holes through the side of the drum! So they may be stronger now, or maybe you just have to be real clean with them. As you guys have explained you have some time to get a drum turning and kill a load, but pretty much everything went wrong here. For perspective this is the only one in 11 years....and as a mechanic I must place the blame firmly on the driver of course
Lesson Learned, Thanks!
I do know if your planning on driving a transit mixer any great distance with the drum not turning the factory installs little wear pads between the drum and the rollers. The motion from driving down the highway with stationary drum will actually rock the tower back and forth enough to wear flat spots in the ring the drum rotates on.
That is why you always see the drum turning even if the truck is empty. Those flat spots are a PITA, especially on a front discharge. We never had one flat spot the ring. Just the rollers, and when the rollers are right behind your head they make a racket if there is a flat spot on them. At least they are easy to change out, just heavy!
Another great way to get flat spots is to fire it up on a cold morning and your rollers are frozen but you just let the drum keep turnin'. Easy to change?! I guess once you chip all the hard concrete off of them, chain the drum up and raise it with a loader it is only four bolts. Still a job I try to delegate.
better call mythbusters so they can blow it up