This question is about how accurate popular reday-mix kits are compared to the real thing. Below are pics of some popular kits.
I'm assuming cement and aggregate are kept in the silos, the silo accessed by the conveyor would be for the aggregate. It seems water is not held in a tank, but rather piped in somewhere.
These pics of older european-based kits seem to suggest the mixture of cement, aggregate, and piped in water takes place in the windowed areas, if the plant has them.
Are my assumptions correct? And how many aggregate hoppers or cement hoppers would be needed to actually serve these small plants (to supply the silos with dry cement), if any (served by truck). I'm thinking these are probably too small on their own for rail service.
- Douglas
None of these look anything like the ready-mix plants down here in Florida.
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I have no knowledge of plants operating elsewhere.
-Kevin
Living the dream.
Only thing kept in the silos is portland cement and itnis trucked in. The aggregates are trucked in as well. The aggregates are stored in bins outside and moved to an exterior conveyor by front end loader. The water is pulled from a well or nearby nonpotable water source. there is a loading hopper that is enclosed where all the components are moved to and loaded by weight for the specific mix design. A max of 10 cubic yards can be loaded in the hopper. Trucks pulls under the chute and itnis discarged into the Barrel. The water is added directly to the truck. At which the barrel is spun mixing the ingredients. The driver now has 1.5 hours to get to site and get emptied before concrete goes off. That is on average. Mix design and temp
make that vary somewhat. That is the basic American concrete batch olant as outlined by ACI (american concrete institute)
no rail service is normally
supplied to a batch plant. Now if the plant is in a quarry, that is possible as other aggregates are. Rought in and distributed from there. So it would go from the hopper cars by conveyor to stock piles This type of operation would also have asphalt batch plant as well. And supply aggregates to other plants and aggregate users in the area. Along with what specific aggregates the quarry itself produces and halls out.
There is an ooeration like this just outside birdsboro pa. I think it still belongs to H&K. They have a couple quarries in that area.
Wolfie
A pessimist sees a dark tunnel
An optimist sees the light at the end of the tunnel
A realist sees a frieght train
An engineer sees three idiots standing on the tracks stairing blankly in space
Thanks for the great explanation. Much more concise than anything I found with Google search.
That's what I thought. Water is sourced onsite and is added to the cement/aggregate mix in the truck, where it is mixed in the rotating truck bin.
Having thought about it, if the water was added before the mix was distributed to the truck, any exit nozzle would get clogged by concrete...duh.
I'm assuming in the pics above, the large single bin is where aggregate is held in order to be metered in the correct amount when combined with the cement in the windowed area. Modern facilities would not have the windows, and would not be multi-colored but would be painted probably white or light gray. I think the general arrangement of the silos and conveyors would be similar to the pics above.
There is an industry near me that receives covered hoppers of cement. Its a large concrete pipe factory, for large sewer projects and such. It has storage silos for the cement. There are quite a few, so I think it may also double as a cement distribution facility for smaller local batch plants.
I'll need a kit similar to the above, with extra cement holding silos and piles of aggregate organized in open bins.
I'm using these two structures on my railroad. The Blue Star Ready Mix building I see all around South Florida...
DoughlessThat's what I thought. Water is sourced onsite and is added to the cement/aggregate mix in the truck, where it is mixed in the rotating truck bin. Having thought about it, if the water was added before the mix was distributed to the truck, any exit nozzle would get clogged by concrete...duh.
All the concrete trucks I have seen have a water tank onboard. Many job sites would not have water available. The driver usually needs to adjust the wetness of the mix to suit the finisher and he uses the water to clean up the chutes when the pouring is finished.
As for the nozzle, I don't thing there is one to get plugged up. I guess you are referring to the discharge outlet at the bottom of the hopperP Concrete is discharged into the chutes by reversing the rotation of the drum and that sort of augers it out the back of the barrel. At this time the finisher will tell the driver if he wants it a little wetter and the driver adds water from the onboard tank. Perhaps some one from The Great White North can enlighten us as to how they transport concrete such long distances without it "getting away from them" Do the trucks carry all the water needed in a seperate large tank and add it enroute or at the job to the dry mix in the barrel?
Charlie
Yes. The Blue Star kit is an easy match for an accurate ready mix plant, but it might be a bit too large for what I'm looking for. It is certainly modern, which is the era of my layout and that may be where I end up.
Overall, I'm not sure what facility the first pic is meant to represent. No way is it loading concrete into a railroad covered hopper. I think it was originally an asphalt batch plant kit that Walthers has repurposed into something else. In any case, I think the aggregate hoppers are on the wrong side of the tracks. I'd think they would want them closer to the conveyor tower.
I think the main silos would make for a nice aggregate loading area near a quarry, where they sort/load two different grades of aggregate for shipping in open hopper cars (not covered hoppers)
I pick these kinds of nits sometimes.
charlie9 Doughless That's what I thought. Water is sourced onsite and is added to the cement/aggregate mix in the truck, where it is mixed in the rotating truck bin. Having thought about it, if the water was added before the mix was distributed to the truck, any exit nozzle would get clogged by concrete...duh. All the concrete trucks I have seen have a water tank onboard. Many job sites would not have water available. The driver usually needs to adjust the wetness of the mix to suit the finisher and he uses the water to clean up the chutes when the pouring is finished. As for the nozzle, I don't thing there is one to get plugged up. I guess you are referring to the discharge outlet at the bottom of the hopperP Concrete is discharged into the chutes by reversing the rotation of the drum and that sort of augers it out the back of the barrel. At this time the finisher will tell the driver if he wants it a little wetter and the driver adds water from the onboard tank. Perhaps some one from The Great White North can enlighten us as to how they transport concrete such long distances without it "getting away from them" Do the trucks carry all the water needed in a seperate large tank and add it enroute or at the job to the dry mix in the barrel? Charlie
Doughless That's what I thought. Water is sourced onsite and is added to the cement/aggregate mix in the truck, where it is mixed in the rotating truck bin. Having thought about it, if the water was added before the mix was distributed to the truck, any exit nozzle would get clogged by concrete...duh.
Okay, that makes sense. The driver takes the truck to another location onsite to load the water into the truck. It doesn't have to be real close to the dry mix building. In fact, the company probably doesn't want water anywhere near the dry mix building for obvious reasons.
From the grear green north:
There are two types of concrete to job site delivery trucks. The common one discussed above adds water to the mix at the plant, and has a time limit to unload, and completely unloads.
A second type carries the water seperately, and mixes on the job site, adding and mixing as needed, not the whole truck load, allowing more flexability, and less need to order the exact amount of concrete needed.
Dave
The responses have been very helpful. I'm having a better understanding of the process and therefore a better idea how to model it.
These kits are labeled ready mix or cement plants. Because of that, I was thinking that the ready mix concrete was self contained in these buildings. I realize that kit makers have to have generalized recognizable names for their kits, but the real purpose of these kits are maybe more appropriately called the "dry-mix building".
Also, the large single silos must be used to store and/or dry out the aggregate. Mixing wet aggregate directly from the open bins to the conveyor to the windowed mixing chamber would result in some type of concrete likely being created before it even gets loaded into the truck.
I think the top pic is a pretty accurate representation of a dry-mix building, back in the day. The single silo also has a louvered chamber above the silo, perhaps for ventalation and a fan to keep the aggregate dry? The windowed area would be where workers would ensure the mixture is of the proper consistency. I'm assuming more modern facilities like the Blue Star plant has no need for windows since it either is well lit or the composition metering is automated.
I'm getting better ideas. I think if I covered up the windows of the top kit, it would be an accurate model of a modern but smaller facility. I would want to add a covered shed where cement hoppers could unload portland and the powder would be transported by pipe to the silos.
Back when I worked for the Ohio Highway Department, we received our concrete from a plant at the SE Johnson Quarry in Maumee, OH. The stone was crushed from the quarry to the proper size for concrete (No. 57 Stone). The sand came from a sand pit in Wolcottville, IN via the Wabash Railroad in 2 Bay Hopper cars.
Another point, for Highway Department work the piles of stone and sand to be segregated from the other stone and sand as samples were taken and the material tested before it could be used in our concrete. These piles received more stone and sand periodically and the testing was done all over again. For Highway Department work we did not allow the finishers to add more water to the mix unless the slump of the conrete was less than 3" as a 3" slump was the maximum allowed.
Rick Jesionowski
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Well, I didn't think about sand. Certainly a ready mix facility would want to store it in a covered area. Wet sand is hard to work with.
When making concrete, is it added into the truck like water, or would it be part of the dry mix from the silos?
I can't remember but I think the sand was just stored in piles, we also when it was sunny and hot watered the stone prior to adding it to the plant, as the dry stone would suck the water in and change the mix calculation that was done for the proper strength of concrete.
While working on the Chessie we would deliver 2-3 coveredhoppers of cement once a week.. IIRC it was usually on Monday or Tuesday. We would pick up the empties on the day we dropped off the loads.
The plant wasn't very big but,used a lot of cement..It had two silos and a large gravel pile. The gravel was delived by dump trailer semi.
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
dti406 I can't remember but I think the sand was just stored in piles, we also when it was sunny and hot watered the stone prior to adding it to the plant, as the dry stone would suck the water in and change the mix calculation that was done for the proper strength of concrete. Rick Jesionowski
Yeah, I'm probablyheading down a rabbit hole of minutia here, but it just seems like wet sand would not flow and couldn't be part of the dry mix, meaning it wouldn't be added in the building's depicted by the kits. Its added somehwere else and then the water is added, the amount being influenced by how much moisture is in the sand.
Just thinking out loud.
An important additive/expander for concrete is fly ash from the burning of pulverized coal. It may not be used for roads but for other products it's very important. It is so important, when my son drove a cement mixer, once every 10 or so days, took an 18 wheeler with a cement hauler type trailer and drove almost 300 miles one way, to power plant to pick up a load of it. He said it handled more like a liquid than a solid due to its fine texture, and he had to be really careful going through sharp curves with it.
Why wasn't it shipped by rail? Because our big yellow railroad didn't want to bother with a single carload every ten days. Besides, they had ripped out everything but the passing siding, to emphasize their point.