Help Improve a Portable Cement Mixer for Haiti

Do they have cows? I could swear I saw this on a thread here at some point...............or somewhere. I think something much simpler than this could be rigged up to mix concrete.

http://inhabitat.com/cows-on-treadmills-could-produce-six-percent-of-the-worlds-power/

if I'm reading that right 2kwh per cow per 8hrs or 0.25kwh/cow/hr

13hp is right around 10kw, 4 batches per hr

a batch of concrete takes 2.5kwh

maybe 10 cows to run the mixer

$100k for a 50 cow rig

I wasn't thinking of using the cows to generate electricity. I was thinking of using a cow to direct drive the mixer.......using a harness or something. Or hooking a manual mixer via splined shaft and gearbox directly up to a treadmill............no electricity required. From where you're coming from, I guess electric mixers are necessary......I misunderstood.

No not at all,

I was just using kilowatt hours as the unit of measure

you may have noticed that the size of the mixer is given as 1/2 a cubic meter, not yard.

my math could easily be wrong or the conversion factor not accurate for this case

the figures make it appear that a cow is more powerful than a horse, I have no idea if this is true

the cows could be direct drive, you would probably need a clutch

the beauty of the hydraulic set up is it acts like a buffer, there is some losses involved I'm sure

Just trying to help out. I know they have limited resources down there, plus most of the promised money is tied up in bureaucratic gridlock.

Throwing out thoughts.......................I'm imagining a 55 gallon steel drum with a hollow tube coming up the center, out of that comes a shaft with 2-3 legs coming off the top............kind of like one of those clothes lines that turn around...............harness a couple of cows on the outer perimeter and have them walk in a circle, with the mixer in the drum agitating the concrete.

It seems like the consistency of the concrete is the problem.

I'm willing run the risk of throwing out some some dumb ideas, if anything I might come up with could help the guys on the ground.

I have seen an "olden days" cement mixer used by my grandfather. It was 50 gallon drum with internal baffles etc welded to a wheel that was mounted onto the rear of a modest motor vehicle.

Rear wheel drive, slip enabled differential with the wheel lifted. Forward and reverse provided by the vehicle transmission. Probably no-where near as efficient as your original systems and obviously much smaller batch, but an alternative from "left field".

What if you had a small "dynamometer" style system where a motor car is driven into a cradle that allows the motor driven wheels to drive your system? Many smaller cars are in the drive energy range that you describe. (Understanding that fuel availability is probably also limited.) But understanding that the resourceful people there might harness the waste heat from the engine for water heating or some other secondary use.

(If this is totally out of line then forgive me. I've been out in the sun for the whole day and it was rather warm.)

I'm just trying to help out & maybe bring some ideas

years ago I saw a drive on portable saw mill

any kind of cheap n dirty PTO to drive the hydraulic pump off a beater car or some other bit of obtainium

a horse exercise merry go round, as Kramarat is working towards :D

any good ideas about field testing methods for concrete would be welcome

I saw some mention of something described as a swiss hammer

Considering what they used in the past, one does not need to get elaborate just to improve.

I am sure there are exports to cover this, and with the available man power.......why use animals?....

Use armstrong.... as in man's arm strong...they used it initially, but the process was poor....this time use muscle and this.... and when resources are available...such as petrol, then power it.

After a year, its nice to see people are still looking into helping, with the constant struggle that happens after this.

Are smaller batches possible? This site has some mixers that run on way smaller engines, and one that is completely manually operated.

http://www.shriconstructionequipments.com/concrete-mixers.html

Or how about making concrete blocks at a centralized location and transporting to the site. This would cut way down on the amount of on site mixing required.

http://www.tradeindia.com/fp118737/Stationary-Type-Concrete-Block-Making-Machine.html

Blocks are nice, but that's a different problem, where you could be able to have process equipment

the main need this group is trying to address is the pouring of slabs & stub walls for foundations

if you were going 5" thick 1/2 yard batches would make around a 6' X 6' square [very rough numbers]

I looked at their site their claiming 3 cubic meters per hour, which is faster than the 15minute mix time, I was quoted.

so what do you think may be keep 4-5 guys working?

The measuring system, wouldn't be as effective on a smaller rotary, moving past the shovel as a unit of measure is one of the main goals

Maybe I'm off base, but I'm thinking if they could eliminate the need for gas or electricity, it would help immensely. With four or five guys on a job site and one of the units you link to, I wonder if it could be used manually. Here's a very crude drawing of a possible handle setup coming off the mixer. With 4-5 guys, turning would be fairly easy. Each turning section would be about 2' wide x 1' deep, (enough room for each worker to stand next to the other). Each section would be fitted with a slide handle that would spin as it was being turned, so they weren't ripping up their hands. Again, a splined shaft assembly would have to be fitted to accommodate the matching end of the handle.

Does this make sense, or am I way off base? Crappy artwork, but I think you can get the gist of it.

You're on the right page

add a pair of legs & a bearing going to the ground on the end opposite the mixer. 90 rpm is a pretty good clip

I think we run into basic limitations of the human body, it would take maybe 20+ guys to do the work of a 13hp gas motor... Which explains why guys with shovels make crappy cement

It's really hard to beat the energy density of liquid fuels.

Maybe some piston pumps hooked up to a stair climber, charging a hydraulic accumulator?

I wonder if the design of the auger could be improved? It's really a ribbon mixer. For dough you would use a interrupted flight. I suppose that could make cleaning more difficult

It seems like if consistency of the concrete is the primary concern. One thing they do have down there is plenty of people. Rather than trying to replace the 13HP motor, they could extend the mixing time at a slower RPM.................Good concrete, and the workers don't have to kill themselves mixing it. They could even trade off in teams.

Like was pointed out in the original discussion, gas engines and powered mixers are great, but if they break, or if they run out gas, they are useless. Something like this would take longer per batch, but the fact that it could be run indefinitely, with little chance of breakage, and no gas or electricity required, would more than make up for it.

I like the idea of bearings on the outside end to hold the handle. The bearing set up could just sit on top of a triangular stand and the handles could be offset, so as they're turning, the force would be somewhat centered along the handle.

Where the hell is everybody else that should be chiming in on this thread?

I was too late for the daily digest yesterday & I put it in sustainable engineering, so the thread should have more views tomorrow

Maybe something like a rowing machine, so you could use your entire body instead of just upper body

I don't know what the actual power requirements are, the 13hp honda is common, though the output is more like 11hp.

Likely the hydraulic set up is the same as one of their other trailer mounted rigs, that they sell along with the mini batch plants, you see at places like US rents

the hydraulic pump/motor set up is probably 60% efficient

a benefit of the existing design is no dump, which helps keep it simple

Mixing the western way, you put water in the mixer and then add sand and cement in proportion until either the mixer is at capacity or the mix is thick enough. But if you are in Haiti where fuel is probably really expensive you need to be much less energy intensive.

I agree with kramarat. The key is to get the proportions right. Shoveling will not cut it. Some guys take big shovels of portland, some take little ones. And portland settles, a fluffy big shovel of cement weighs nothing. Sand shovels are often a lot smaller when the sand is dry and dusty than when it is a little moist because the sand just rolls off.

So the key is to mix by weight in batches.

If you mixed it dry first, then a few guys can easily get it wet enough close to the site.

As long as you keep the dust down (mixing dry in a closed barrel or a slowly rotating pipe with some sort of internal paddles (don't need to be big)) is way way less energy intensive than the normal western way.

On small jobs we mix navyjack (which is gravely sand) with portland dry with the shovel and then add water in a 6 cubic ft wheelbarrow. It takes about 5 minutes per mix.

So that's about 3 cubic ft (because we don't do a full wheelbarrow) per mix in 5 minutes. 5 minutes is easy with the gravel sand. When we mix for outside rock walls, we use coarse sand and make a much drier mix and it takes a little longer and more work.

So weight is the key. If you mix in a mixer, without weighing the material in, you are just as likely to screw up as if you mix in a wheelbarrow.

You just screw up more efficiently.

Premixing the cement and aggregate is one of the critical parts that requires the most supervision with unskilled labor, and I'm wondering if it might be possible to pre-weigh batches at the point of local distribution before taking them to the site. Those large polypropylene forklift bags (bulk bags, FIBCs) come to mind, but in smaller sizes. Wherever the gravel is sourced, it can be pre-weighed to be the appropriate amount to be mixed with one bag of cement. Then the onsite mixing laborers only have to do a one bag to one bag ratio. They can use shovels, buckets, hods, or whatever to move the dry stuff into the mixer, as long as they have one empty cement bag for each empty aggregate bag. With two poles and the handles on the forklift bags, a couple of strong guys or 4 weaker guys could carry a bag of 400 lbs of sand and aggregate from the truck to the mixer. In smaller sizes, the bags cost about $15, and they can be re-used again and again.

Your very rough numbers may be rougher than you think

½ yd³ would create 21½' of 5" thick 18" wide strip foundation

½ m³ increases this figure to 24'

If you are paying for ½ yd³ of concrete to surface an area of 6"x 6" x 5" thick, I guess that you must work for the Department of Defence.

you misread I wrote 6' X 6' [6 foot by 6 foot], not 6" X 6" [6 inches by 6 inches]

how rude!

Give the guy a break...................I think

If I had a nickle for every time I was rude...............................................

yes, while I am forgiving, I think it imperative to identify poor behaviour.

(unless its me of course )

back to the topic... I have a few questions.

Where do the Haitians get their raw materials, (sand, gravel, cement, and water) and how is it transported to the mixing locations?

If trucks, then why not adapt the trucks mix or provide some power also?

Is the cement imported?

I think we need to know the equiment and sources of energy used in the supporting industries first, as the ultimate goal is to produce strong concrete, in a timely and economical manner, at the selected locations. Beyond that, the goal is to provide living space... _{^{which of course, brings us back to shipping containers...}}

Are the raw materials available in Haiti? I would think that equipment to crush rock to make gravel would also do a good job of pre-mixing the ingredients. I think that if it is produced in Haiti, then some of that infrastructure can be employed to assist in producing good concrete.

If the infrastructure does not exist in Haiti (or Dominican Republic), and importing materials is required, then I would seriously suggest that other materials be used. Building materials are expensive, when cross-ocean shipping is required, then freight costs are significant. Using lighter construction materials makes more sense in that context.

As Garthh has basically stated, simple infrastructures can be intelligently applied to produce a diverse array of products, but I think that we need to know more specifically what that infrastructure consists of currently.

I realize that the intent of the thread is to provide methods that can be implemented very simply, and that the aid money has been largely stolen, and they must get along as best they can.

Chris

Now, I'm not a rocket scientist. But I've heard tell of all kinds of money promised to Haiti. Where is it?

Call me what you will............I think of myself as a realist. In my mind, the lack of international interest indicates to me that everyone, (besides the people there helping), are holding their collective noses, and waiting for mass death to take place.

It's a hell of a lot easier to bury bodies, than house and feed them.

Of course, my inherent distrust of government, any government, is completely unfounded.

"It's a hell of a lot easier to bury bodies, than house and feed them."

sad but true.

It's a damn shame.

Howdy Chris. I think you're on the right track here by questioning where the basic building materials are originating from. That makes complete sense!

Now for the rest of you folks dreaming how to provide alternate power means for the freaking cement mixer: If the Haitians do indeed have to import Portland Cement in addition to concrete block (CMU), steel deformed reinforcing bars & wire mesh, then of course that means that they have to equally import those materials right along side just about everything else that's required to build homes, shelters and structures. The cost ship-borne freight for cement is a heck of a lot greater than wooden products when comparing the costs and unit weights between the two material types on a cubic foot comparison basis.

And this brings me to this point, and this is a no brainer, it is highly likely that Haiti must also have to import wood plywood and timbers since their forested regions have pretty much been stripped of acceptable trees to be used as timber products. From a construction economics standpoint it's been my experience that the cost of constructing properly reinforced concrete and/or concrete block structures is much more prohibitively expensive when compared to constructing pre-fab or even stick-build wooden structures. Additionally, wooden or cold-formed steel (aka light gage steel framing, though more costly than wooden elements is also greatly stronger) framed structures that feature properly designed and constructed integrated interior and exterior SHEAR WALLS can resist design Earthquake and Hurricane wind forces.

So far, and sorry to say, the Haitians have demonstrated that they cannot properly design, and especially construct, concrete and masonry structures strong enough to withstand seismic events and hurricanes. All you have to do is look around most of the country, and especially Port a Prince and see the devastation that occurred with concrete and masonry homes and other structures. Nearly all were wiped out, and sadly, many dead! First off, and on a grand nationwide scale (meaning everyone involved, from poor to the rich), there are very few qualified senior or mid-level structural engineers present there, let alone those natives that any possession of the necessary engineering (structural) education basics to perform the proper design functions in order to determine the aforementioned forces, let alone design the seismic or hurricane related structural elements needed and thereby incorporated with those homes and structures. Nor do they posses the adequate construction tools, equipment, and finally the proper construction knowledge base to construct safe concrete/masonry buildings.

In conclusion, they need and HAVE to steer away from constructing concrete & masonry structures, and instead, adopt easier constructs requiring cheaper raw and finished materials to buy and build with. Don't forget that constructing structures in general costs many more times than wooden or steel framed structures because of raw material costs. equipment and tool costs, and not least, very high labor costs. Concrete costs are roughly a 2.5X PLUS in higher magnitude that comparable wooden structures on an area/volume basis.

I want to add that they can build wooden structures with quite ease. Nearly any able bodied adult and teenager can swing a claw hammer and drive nails.

Leave the use of concrete in structures solely for the shallow wall foundations, but make sure they're designed & constructed properly with the proper amount of rebar.....what is needed is a standardized design for various sized buildings and occupancies. I'm sure there are some structural engineers on hand in Haiti, whether they're a national or a relief agency worker/volunteer that can simply design the shear walls.

Toss the damn cement mixer, except where it's needed to make a concrete batch to be used in the wall foundations.

Sorry if this ramble on somewhat, but it has been a very long day here.

ps: GO JETS!!!!!!!!!!!!

Even though I am a great advocate of blocks and earth, the fact is that in almost all respects, I agree with you. However, until I get "on site" and see what I have to work with, its all hot air.

Well there is

as a mixer,

the company [cart away] that developed it ,was wondering about a way to use human power.

at this point we have our imagination to work with, I was attempting to use stuff that would be possible to obtain used & cheap

I missed on the front drive transaxle, back to a rear drive then

chop off one side & lock the axle

the different agencies [red cross & others] are sitting on the money

It's all neatly tucked away in the banks, and the damn bankers are making a HUGE fortune of the roughly $90 Billion USD still remaining and not parceled out to Haiti yet. Most likely they're the same banks the US Government bailed out one and one-half years ago! Also, the very same bankers who have strong political ties (as in very large Political Campaign Contributions and PAC's) with our elected Representatives.

I use one of these here at the house. It doesn't make large batches, but it could easily be changed over to manual operation without much trouble.

This is all guess work on my part, since I'm not in Haiti. But I think they are aiming too high. Finding a way to make small, consistent batches, that don't require gas or electricity would be far more efficient in my view, than using something larger that requires power. Unless they could get their hands on something like this. Fairly small vehicle, large payload, etc.

Notice that the company http://www.theconcretemd.com/default.htm builds Batch plants

they do have a high level of expertise in concrete,

all the parts for the mixer probably came off the shelf, except the hopper & batch buckets.

the rubber lined hopper is a nice touch...

I just had to reread your OP. I guess they have determined that these units are the way to go, but how to run them without gasoline engines is the problem. Aside from the handle idea, I don't know. Maybe Life is everventure, will come back and wow us.

His idea actually has merit. If they were to use the two man railroad car concept, it might work, but the handles would have to be very long to gain the leverage needed for two or even four guys, to turn the auger.

Now you see what I'm seeing

That guy might as well be another drive by guest, he uses the same kind of technique on most every thread he joins.

I posted back to the Rewired forum asking for some more info from the mixer guys.

the railcar see saw is similar to the rowing machine concept I floated a few posts ago.

either way you could use a ratchet to determine the direction

The problem I see with something along those lines is they have the mixer running at 90rpm & bicycle, tread mill, handcar, rowing machine or horse walker are going to be 10 strokes or so per minute. A gear up is going to require longer levers reducing the strokes some more & increasing the number of people

maybe it can be done with 4-6 guys providing the power [pairs is probably going to be the best]. A crew of 20, rotating between the different jobs?

If we're strictly thinking about the most efficient use of human muscle to mix concrete, I keep coming back to the traditional mixing drum with paddles on the inside.

The reason being, is that the center of gravity can be adjusted so that less force is required to do the turning. As far as controlling the dumping of the concrete out of the drum, couldn't that be achieved with simple hydraulics? Again, no engine required.

My problem with it (if I follow you correctly - a vertical drum with paddles on a vertical axis) is that it would be stirred rather than mixed. I don't see how you can get sufficiently thorough mixing without applying the force/torque that you need to churn up the makin's in a traditional drum-type mixer (unless you mix it for much longer). This stuff has been made for a looong time now, and I'd've thought that if an easier way of getting it thoruoghly mixed could be found, it would've been.

_{Sorry, Garthh (et al.), I haven't followed all the links - so maybe I'm bullsh*tting.}

I own one identical to the red one in post #19. Granted it's not very big, but it's far less than 90 RPM, and yes, the internal paddles do "mix" the concrete. I think 34point5 is kind of on the same page.

Concrete has been around for a long time, but how do we eliminate gasoline or electric motors from the equation, rely on human power alone, and do it in the most efficient manner possible. While at the same time, ensuring a consistent mix, one batch after another.

Isn't this the type of question that engineers have wet dreams about?

Well I'm not on any page as yet - just supplying data.

To 'enlarge' on the auger design, it's rather like the intake of a concrete pump, but split to pump to the center, cause a welling up and so recirculation. It is likely a very good mixer action, but will be higher in friction and wear than the tumbling action and resistance of dragging a paddle up through a mix falling due to gravity.

In the barrel approach, I don't think rpm is that important. It is more a case of number of paddle 'wipes' to get a mix. Or slower rpm means more paddles. But it's still going to be the same hp-hrs, or kW-hrs for a mix.

Similarly, in the trucks, mix is done on the run to the site. Close sites mean higher rpm - far sites, slower.

The larger the drum the slower the rpm required as its necessary for the mix to fall relative to the drum tangential velocity. Not coat the drum due to centrifugal force. Or over aerate the mix by excessive 'thrashing' - in fact the action has to de-aerate the sand and gravel, supplanting it with water and cement.

De-aeration would be a major advantage of the auger approach - so long as the auger is fully submerged. I imagine the auger rpm is critical, to pump effectively but not aerate. Meaning a partial batch might be difficult.

I.e. the peripheral velocity of a drum determines the rpm.

As bigger means slower - or less gearing against 'animals' - I would be inclined to explore drums.

This leads to a comment on why ICE's are ~ 13 hp against 1 - 1.5 electric in small mixers;

In trucks the 'paddle' is an Archimedes screw. It runs "backwards" to mix and "forward" to eject the end product. This means mixing is a constant 'over flow' of the spiral helix, so fairly constant torque.

Straight paddles produce a pulsing torque, the peaks of which would confuse a 'right hp' ICE. So larger and more torque-y ICE are used.

This peaking was noticeable in the bike guy struggling.

I.e. your drum design may be more 'animal power' friendly, with spiral paddles. (and possibly require less kW-hrs per mix than indicated in my previous post)

Which actually raises the demographic side of things. What of the proportion of women? Can they to do this work? Should the design enable 'girl power'.

And deviating well away from the OT inferences - do I remember there was a very large proportion of under 15's in that HIC post EQ data?

May put you back to thinking 'capstan' + height adjustment + spoke options.

Could be quite simple compared to rowing. Much larger 'workforce base' too, inc an ox option.

Would also tempt me to re-think 'drum' in terms of drive simplicity.

I've got a couple of questions pending other places

the most efficient mean to turn human calories into work output

minimum batch size in average conditions [temp, humidity] in Haiti

the capstan approach reminds me of the scene in Conan the Barbarian

kicking it around a bit with you through email, my interpretation of a potential design a capstan example: http://www.hotwalkers.com/ using a junkyard differential to transmit the power over to the mixer the frame for the people to push possibly made out of bent steel tubing, [2" conduit?] a front drive differential from say a toyota or honda, would be fairly common the frame work would be connected to one of the splines which on a car would normally go to a wheel [drive axle.] the other side being locked down the clutch side connected to the mixer, low to the ground, with the drive shafts, the cv joints would help. a typical differential being rated for over 100hp & much higher speeds running it backwards wound increase the output speed around 3 times, which gets it in the neighborhood of 60 rpm at the auger. set up for 6 people to push, I'm thinking 4 can do the work, the extra spots for substitutions mid batch Any thoughts?

Yep - fairly well where we got to - but I haven't had time to do the Excel on the axle torque yet. Slow speed into a constant load might have "polar moment of inertia" (wind-up) issues. ^{_{Maybe I could get Sue onto it}}

Or the car boy's know the GB ratios and engine torque numbers.

I'm not sure of the cars you mention, but a lot of front drives use 'spurs', not a crown & pinion. I.e no free 90⁰ translation for a shaft output - though chain might do it.

All in all; I'm thinking it might be time to see if Canadian Chris is in a position to help on this? Or maybe someone else has time to develop some models or visuals that can be posted as 'discussion aids'?

I was thinking of this too. but was almost giving up til I figured that the fixed part (stators) could be above the mix, and lowered into it... and the rotor blades work against the stator blades to provide... like a helical motion to the mix as it turns.

I like the idea of using premix aggregates, and measured water inputs as a recipe approach.

the trick is really getting the mix out of the flat toroid.. I'm still thinking about that..

Greetings again.

If you are all still bound and determined to build an actual mixer system we still need to be thinking simple and cheap. A helical or planetary motion mixer will not be simple or cheap to build or maintain. A simple drum mixer with solid fins that simply reverses motion to discharge the mixed concrete will likely be the simplest and most feasible machine to construct. If we are starting to cannibalize cars, a drum could roll on two of the non-driving wheel and axle assemblies and the driven end of the drum could easily be carried by the driving axle assembly. Old 500 gallon or better oil tanks could be modified into the drums. The fins could be cut out of the end of the drum. Commercially produced machines of course would be superior. In an environment like Haiti one might start considering volumetric type mixers instead. Google up Quick Mixers or Reimer mixers and look at the auger type mixers they use along with simple gate controlled aggregate feeds. These small systems are very cost effective and have the important advantage of mixing only the amount of concrete you need as you need it. In a hot climate this can be critical.

Food for thought, even if it is only bread crusts.

Heat is a good point - with less than 'organised' workers.

Could be quite an issue if it started to go off in an auger system

Check out the videos on how the augers work. They are open and easy to clean and the concrete mixes and dispenses in 10 to 12 feet of auger length. It's pretty remarkable how well they work. Early set of the mix is not an issue in the machine. Cementech is another major manufacturer of volumetric mixers. They have a great website you could go to. I truly think that these type of mixers may well be the best way you could ensure consistent mixes with unskilled help. Once the machine is calibrated it simply needs to be kept charged with materials and it will dispense the proper mixture. Of course no system is completely idiot proof. They just keep making craftier idiots.

I'm thinking forget the transmission and put the capstan arms directly onto a rotor-assembly that drops into a drum and does the mixing.

I can't say you're wrong, this could be one of those instances where they have preconceived notions about how things should be done.

I was just looking around at batch plants they all seem to use auger to mix, it's probably the fastest way. speed being more important than energy efficiency

I peeked ahead while I was looking around at batch plants & saw Vlad's answer

7.7kw to run a 1 meter bucket, I'll continue on to 5 batches an hr

7.7/5=1.54kwh per sq meter of concrete X [4 man days/kwh]=6.16 work days per batch X 8hr days X 5 batches per hr = 246

250 watt / 8hr day = 31.3 watt per person per hr / 5 batches per hr, a person contributing 5.2 watts per batch =270

I must be doing it wrong?

that's an awful long handle, that will let 200+ people turn it :D

oh wait only 1/2 meter batches, so only 100+ people, would make 20 sq meters per day

Let me just put it this way. Once again, I've been drinking. I'm not an engineer. And I know for a fact, that some incredible and long lasting structures have been built without gasoline or electricity.

Sometimes, I could swear, that with the advent of technology, we, as a race, are unlearning the basic skills of survival. I feel as if this is a fact.

Take any smart a$$ from CR4, or anywhere else for that matter, knock him back about 500 years, and how is that person going to fare?

Dead in days is my guess.

As technology advances, the human race is devolving.

I'll shut up............I'm going off topic

I think you would be surprised, being able to do with whats on hand transcends whatever level of technology

This particular situation is using technology to make up for organizational deficiencies

Well that's a load of crap if I've ever heard one.

What the hell are organizational deficiencies?

A huge part of the problem, now, and in the past has been the absolute corruption of the Haitian government.

The Haitian people's lives didn't start sucking because of the earthquake........they always sucked.

You seem to be in love with government, shouldn't all things bad just be fixed?

Put trust in the motherf^^ing government, they will take care of us, right?

no building code,

there was just a corrupt election

the ownership of a big % of the property has not been clearly recorded so title is unclear.

no infrastructure outside of the gated communities

But yes I think they should have a government.

You seem to think government is at the root of all problems in everything

the corruption of government, by thems that have is more like it

I am not anti government. Dammit, here we go again.

Governments, whether it's the US, or anyone else, should represent the people.......period!!!!!

WTF

I'm getting tired of arguing about whether government is bad or good. It is absolutley necessary. It's what they do once in power that truly matters.

Let's face it......................the Haitian people were not doing well before the earthquake. And as long as a corrupt government is in place, regardless of the money that pours in, they will continue to be screwed.

Correct me if I'm wrong Garthh.

"Dammit, here we go again."

US political 'positioning' is getting as bad as religion.

Don't make me think I did all that digging, just to see this go the same way as a list of threads lately.

Either of you.

Solve "concrete" guys.

Just because you're a dog with a mask, and you happened to dig your way to the other side of the fence, doesn't mean it's better.

If that's you in the picture, let's get together and work on some multiplication.

Let's see, what's 34.5 x 2?

I kid.

The money's not pouring in except to the various administrators, other than debt relief [bankers getting paid] around 10% of the money donated has been used

there is a huge unelected international bureaucracy in the business of disaster

busy justifying their continued existence

more correctly here you go again :D

I'm more than happy to talk about the technical bits

But I can do the failure analysis of this thread

the cart away guys want to explore ways to adapt their single auger mixer to the conditions that exist on the ground in Haiti

Or...........here I go again defending the government.

Kram a rat is blaming the government for not having work.

You know damn well that was nonsense...............on your part.

No not so much nonsense 1+1≠7

you concluded that it was the governments fault that there is less construction & consequently less work for you.

Who made the most money on the housing bubble?

Who pushed for banking deregulation?

Who can't be bother to post on the right thread?

Math and weekend afternoon drinks don't really go together, but here go's

1 m³ = 10 m² @100 mm (~4") thick.

If a mix took 6 min. of power @7.7kW rate (and it may not, but) 5 mixes/hr = 0.5 hrs/hr - or 50% duty cycle - or 3.375 kW-hrs/hr.

Equally; a work rate of 250W-hrs/day would be expended against the 50% duty cycle - or in 4 hrs.

So you have ~ 500W/man/day to service ~ 7- 8 kW. Say 14-16 men.

Out of that you get 5 m³ x 8 hrs = 40 m³ = 400 m² of 4" cover*, or ~ 27 m²/man/day

(*could be say 2.5" ground slab and footings)

Comparing that to the shovel guys competing with the bike, they made 'a barrow' which is typically ~3.25 cft ~ 0.8 m³ = 1 m² @ 80 mm t (~3").

But ignoring the 20% volume, (and quality?); could ^{_{(not, would)}} those 2 guys, do that 27 times a day? I.e. once every 15 - 17 minutes?

Tough job - but I would think 'plausible', as in, are we in the 'ballpark'? on 'order of energy' available/required per m³.

But as said, design the thing with 'peak efforts minimized', and inputs should fall.

Then, by suiting the volume to a human number/duty cycle, or available beast capability, it could be very doable.

For Mark

Looking around some more, it's not real clear what a realistic figure for human output/hr is?

250w / 4hrs = 62.5w per hr per man?

62.5w / 5 batches = 12.5w per man per batch ?

or no?

"Looking around".... what is mostly missed is; output relates to diet - watts intake.

So the huge numbers for weight lifters, cyclists, Olympic anything, pro sports, and the like - are ridiculous to apply to general population, even a well-fed, large body-mass one. Certainly not to a "40 lb when dripping wet" Asian, or an undernourished Haitian.

Also 'not clear' is 250W/day is more like $250/day - you can spend it all in an few minutes, or an hour, or evenly over the day.

So yes - in saying 50% 'duty cycle', the 'spending rate' go's from 31.25W/hr, to 62.5 W/hr.

But it could equally be 3 or 6 hrs, but presumably that alters the production volume proportionally, so is the same W/batch outcome.

So that batch outcome guesstimate is quite key to everything.

We need to know;

A. 'what is the actual motor load on a mixer' - (base number for a proper quality load)

B. can it be reduced through better paddles? (peaks leveled)

Know that, and your in the position to know how many men and how best to spend them, will they fit, even estimate what extra food they need.

I wonder if Kram has something that needs concreting? and can measure his watts?

My question become what is the maximum amount of man watts can we expect to be applied to a load? you know where I'm going, can this be done with 4 guys?

the sail boat thingy is all upper body, bicycle legs [recumbant different legs], hand railcar more upper body

Well 4 guys can make a "4 guy batch" - which, on what I worked out when drunk earlier, would be 1/4 of what 16 did, or 0.25 m³ x 5 mixes/hr x 8 hrs = 10 m³ /day.

Just a matter of scaling the batch to #men.

According to the bio-mechanics lot, rowing (as in sliding seat in sculls) is the ducks guts for "all body power" tapping. But it is difficult to convert to a continuous rotary output, short of quite sophisticated hydraulics. I.e. recumbent bikes were a shot at this, but the irony is they only reduce the upper-body work done in applying greater peddle force in the upright position. Legs only power but drag is reduced.

Similarly upper body work (standing) works the entire body. Or the 'spending' is same as lower body work in cycling.

The choices of legs over arms, is more about do you want high force at lower speed, or higher speed at lower force.

Traditionally when some heavy manpower task was undertaken - like hauling an anchor - the capstan was 'the proven method' of tapping the most power per man in a swarm. And, they needn't be of the same size, or same strength, nor can they get away with 'free loading' - like on the back of a tandem cycle.

A communal hands-on device also lends it self to 'team spirit', work songs and what not, where a row of bikes is 'my bike' and their bikes. Scrum sleds would be the 'modern equivalent', of the capstan. Tackle dummy, of bike.

But hey, I digress into my HIC Haitian self respect re-building "commie pinko shrink rubbish".

What I'm thinking of is 20 men total & rotating 5-4 man teams

mix a batch, break, screed, wheelbarrow, finish

Repeat

can 4 men make a 1/2 meter batch? seems doable

for the rowing machine 2 opposed pairs of rowers, linked to a crankshaft, the crankpin for team#2 offset 90degrees for team#1

You would blow them out fairly smartly. 1/2 m³ is a lot of concrete - think 5 barrows - 1.3 tons being dragged up the side of the drum.

But perhaps, whatever the device is, it's a case of starting with a load their nutritional level allows and 'training up'. Just doesn't want to be so hard that 4 nubies flake mid mix.

I see the principle of the crank and rowing. Trapeze like 'con-rod'.

Rowing is a long stroke, 4⁺ feet. Makes for big crank throw. So keep an eye on 'hidden extras' involved in not killing passers by.

As 30 strokes/min is a fair stroke rate, consider a sizable flywheel.

Might be an idea to think how you'd change one out, 'mid mix'.

Just thoughts.

crap, 2800 pounds, I do remember some talk of 3000 pounds by cement trust

all is not lost, since it's not exactly a dead lift. 6 rowing positions, crank pins 120 degrees apart, use 4 of the positions, the empty spots for replacements or full up as the crew gets trained & in shape. I never did actual sculling, been on a machine a few times, where the stroke was more like 3 foot

I'm still hoping for the auger

when I was looking around at batch plant designs most of the design used a ribbon type auger design with an inclined tube.

I think this type auger could reduce the load, which would increase the mix time as long as we didn't get the utilization to high, but maybe a bit above 50%. I don't know what the minimum amount of loads per hr & have the adhesion acceptable

but the support struts could introduce air

No it's not a dead lift and if you keep the scale updated its a lesser drum and so torque /gearing picture.

Don't be too precious on the aeration thing. I was just meaning slower than 'white water wake'. Anyway, lot will come out at the first bump the barrow meets.

As to your auger idea - I don't follow. Maybe PM me the back of an envelope?

But equally I don't see a 'brick wall' here either.

I was mistaken, I could only find solid flights on the pics of concrete batch plants.

no matter the auger I'm proposing would look like

When the concrete piles up at the end of the hopper it won't take as much power to fold the mass back on itself

cheaper to fabricate

more like a ribbon mixer, as would be used for gunnite or stucco

at 20-30 rpm, you are right about the aeration not being a problem

Say you take a "bit if both" here.

Rather than having it horizontal pushing into a face, tilt it, and trough, say 45⁰up and have it pump upwards, so the stuff is recirculated by gravity.

The non-solid design is then also an advantage, as it allows a % of falling down the axis - or split flow - giving, I would think, more rapid 'de-clumping' of bucket shots.

My "up" reasoning here is; as your first process stage is 'dry mix' sand gravel cement (and/or lime ), (which is not really made clear in the various links) (and done wrong in most), this is where the wear and graunching happens, especially if they go gravel first.

And/or (given our low power levels) pushing dry aggregate against a wall may produce a lock up.

On the other hand, 'lifting' will need a tighter auger tolerance, or sweeping fins added, to wipe the bottom plate. It also might mean a cone, in plate or auger, to avoid a central 'dead spot'.

However, as pushing down would be more productive in 'shearing the cement' to the aggregate, it might be worth considering 'adding mix' phase is "up" and 'main mix' is "down". I.e. fit reversing and maybe triggered by a rev count dial tracking/delineating 'phases'. Say 'load'.... 'dry' ...... 'add water'.......'main mix' (reverse trigger) ........................done. They can watch and see the goals tick off.

This is toward making them do it right. I.e. to that diagram in the 'dry mix' link above.

Aside from importance of process order and times, to consistent product, you may also notice they cite less than 700 W for 3.5 cft.

I also noticed a bit in here on 'kiln fuel', which relates to slaking lime energy (link above)

I'd be interested in seeing the rubber lined hopper & clearance to the auger of the present design.

I was working up to the inclined design, this moves the discharge to the low end, drive to the top. Everything wrote about mixing seems intuitive.

the inclined hopper design would add some complications:

increased loading height, the minimum height is determined by a wheelbarrow

the drive being off the horizontal, would increase the complication & costs. certainly not deal breakers. A drive axle & cv from a junkyard or Ujoint & yoke being potential solutions off the top of my head

wish I had a shop to build it in :D

Just an observation, cause I am no expert.

Given the relatively high temperatures in Haiti, the smaller the unit the more of them you would need to do a proper pour of a slab. The larger the slab the more units you would require to keep up with a near continues pour so the leading edge of the concrete would not dry out and mix properly with a new load. Spraying water on the edge to keep it wet, just doesn't cut it as it would weaken the concrete substantially. The edge can sit open for a few minutes but 15-30 minutes before joining the pours is way to long in my view at 30-35 o C. So maybe its just not poor mixing of the concrete that makes the slabs weak and substandard but also a lack of basic understanding of pouring concrete properly.

Are there any cows left alive in Haiti at this point? I think I would forget about using them for power generation as most likely they've already been slaughtered and eaten by the Haitians.

If the issue is poor concrete quality, half of the battle of getting a good quality concrete is proper proportioning of the concrete mix, by weight. Of course mixing it properly is essential, but not nearly as important as getting the proportions correct from the get-go, as others have suggested here.....as I see it, 30 monkeys can mix the concrete and still get it right.

I have an electric motor on my cement mixer here and it works very well....bought it from NorthernTools.com in Ebay for a cheap price. I can imagine if they can get electricity to any jobsite they could run one of these mixers, then it would probably be far cheaper to run an electrically operated cement mixer then a gas-operated one, wouldn't it? I don't know if they even can get electricity, grid supplied, in some sections of the country or even how much it costs per kW-Hr, or what it costs for a gallon of gasoline?

If there are any sugar cane fields left standing in Haiti maybe they can produce Ethanol to blend with the gasoline on hand, thereby lessening the cost?

Got any info on how much power it takes per batch?

Take a look at the machine I linked to & you will see they have attached measuring tools, to allow for consistent repeatable batches

got any good field testing methods?

this looks cool http://www.silverschmidt.com/home.html?L=0/

& a better drawing with price http://www.gardco.com/pages/hardness/schmidthammer.cfm