Don't stretch that concrete!!

Bigocean

New member
Nov 25, 2010
255
2
0
I was watching a house being constructed near one of our projects yesterday when I dismayed to see them using the campo method of mixing concrete on the ground to make the cement to fill the columns and vigas. I questioned the Maestro and he said that he "always" did it that way and that now with the high cost of cement, he could "stretch" a bag further. This habit is unfortunately common for casitas built in the campo by poorly trained builders, but this dangerous practice seemed out of place for this multi-million RD house (I would guess 5 million) on the outskirts of Santiago. Adocem (Asociaci?n Dominicana de Productores) constantly denounces this practice but there are still builders who choose not to purchase/rent a mixer or use hormigones so they can save a few cheles and then proceed to construct a substandard and dangerous house for the unsuspecting owner. A word of advice, never use a builder who doesn't at least use a concrete mixer (and the correct mix of sand, cement and water) for the structural components of a project, although I would only accept hormig?n for the loza.
 

La Mariposa

Bronze
Jun 4, 2004
1,843
60
0
I was watching a house being constructed near one of our projects yesterday when I dismayed to see them using the campo method of mixing concrete on the ground to make the cement to fill the columns and vigas. I questioned the Maestro and he said that he "always" did it that way and that now with the high cost of cement, he could "stretch" a bag further. This habit is unfortunately common for casitas built in the campo by poorly trained builders, but this dangerous practice seemed out of place for this multi-million RD house (I would guess 5 million) on the outskirts of Santiago. Adocem (Asociaci?n Dominicana de Productores) constantly denounces this practice but there are still builders who choose not to purchase/rent a mixer or use hormigones so they can save a few cheles and then proceed to construct a substandard and dangerous house for the unsuspecting owner. A word of advice, never use a builder who doesn't at least use a concrete mixer (and the correct mix of sand, cement and water) for the structural components of a project, although I would only accept hormig?n for the loza.

It's not a campo method, it's a dominican method and other countries method too. I agree with you ''don't stretch the concrete'' not in town nor in the campo.
 

AlterEgo

Administrator
Staff member
Jan 9, 2009
23,097
6,247
113
South Coast
Last year we had a lot of concrete work done at our house - extended the house 12 feet down one entire side, so walls and ceilings/roof, a 35'x20' raised terrazzo [no roof yet, next year], extended block wall, etc. Our son-in-law was there for about 10 days, he's in commercial construction in NJ [schools, hospitals, firehouses, etc.,] that use a lot of block. He was amazed watching the Dominicans mixing the cement on the ground, and was very suspicious at first. After watching them for a few days, he switched from suspicious to approving. He even took a LOT of photos of what they were doing, wanted to show his boss and co-workers. And don't even get me started on what he said the maestro would get paid in NJ.

AE
 

Bigocean

New member
Nov 25, 2010
255
2
0
Last year we had a lot of concrete work done at our house - extended the house 12 feet down one entire side, so walls and ceilings/roof, a 35'x20' raised terrazzo [no roof yet, next year], extended block wall, etc. Our son-in-law was there for about 10 days, he's in commercial construction in NJ [schools, hospitals, firehouses, etc.,] that use a lot of block. He was amazed watching the Dominicans mixing the cement on the ground, and was very suspicious at first. After watching them for a few days, he switched from suspicious to approving. He even took a LOT of photos of what they were doing, wanted to show his boss and co-workers. And don't even get me started on what he said the maestro would get paid in NJ.

AE

The danger of a poorly mixed cement is especially significant in the structural components (as noted before) of a construction project. As in the house I mentioned, they were using it for the vigas and columns. Certainly a hand-mix for finishing and the like would be less important, but still I would wonder why not at least rent a mixer to assure a more uniform cement? Mixers are not expensive to rent and there are better ways to save money on a construction project than sacrificing on the fundamentals.

My guess would be that in NJ, any construction supervisor that used "on the ground, hand-mixed" concrete to construct a supporting lintel or column would at the very least be fired.
 

Hillbilly

Moderator
Jan 1, 2002
18,948
514
113
Five floors of an unfinished building in East Santo Domingo came crashing down last week....Gee, do you think??????


HB
 

porkman100

Gold
Apr 11, 2010
7,468
39
48
B/o As a gen. contractor for many years, always used ready/mix and pumps, normally a yard of conc. will take from 5 to 7 sacks depending on design mix.and related aggregates. One time I needed just 2 yards and being cheap to have a pump with a set up minimum and ready mix delivery I asked the guys if they knew how to hand mix it, four of the fellows agree to do it, and I learned how fast and efficient it was, maintaining a minimum of 2500 psi. of course.
H.b. I saw the pictures of that building that collapsed, it appears a settlement or foundation problem, the way it lay on its side.
 

jrjrth

Bronze
Mar 24, 2011
782
1
0
~They can stretch it whether it be hand mixed on the ground OR in a mixer, I do not see the OP point on the absolute need for the mixer~

If they are going to cut corners they have the means of completing it either way~ Unless your standing there observing you will not know, and that's if you even know the quantities to mix....That's why they have building codes and standard...but if no one is inspecting them, they can do what they will.......that is until something tragic happens, then everyone will be pointing fingers at others...engineers, architects, and planners...not the Maestro mixing on the ground...he will testify that "No se?or, que el hormig?n se mezcl? con las especificaciones de los planes"....
 

Bigocean

New member
Nov 25, 2010
255
2
0
~... I do not see the OP point on the absolute need for the mixer~

Simple matter of having the tools to do the job at hand. Same reason I would want a carpenter to have a hammer and a car mechanic to have some tools. Having a house of that size and attempting to fill the vigas and columns with concrete mixed with a shovel on the ground was ridiculous. Maestro trying to "stretch" the cement was just icing on the cake. That builder/maestro had no business attempting that level of construction.
 

AlterEgo

Administrator
Staff member
Jan 9, 2009
23,097
6,247
113
South Coast
My guess would be that in NJ, any construction supervisor that used "on the ground, hand-mixed" concrete to construct a supporting lintel or column would at the very least be fired.

You're absolutely right. I didn't mean he took photos to show NJ how they could do it that way - he took the photos because he knew no one would believe him if he didn't.

AE
 

Givadogahome

Silver
Sep 27, 2011
4,397
2
0
Not true. Where you mix does not change the ratio of the mix. Mixing on the floor is simply faster, you can mix more and you can distribute into multiple barrows and get the job done quicker in the end, ultimately getting the mix down quicker which makes for a stronger bond, not weaker.
 
Last edited:

Givadogahome

Silver
Sep 27, 2011
4,397
2
0
Are you saying they are mixing vigas onsite? I'm confused, if so then a poor mix is the last of your problems. Are you sure they are not just using these mixes to fill around the vigas?
 

Bigocean

New member
Nov 25, 2010
255
2
0
Not true. Where you mix does not change the ratio of the mix. Mixing on the floor is simply faster, you can mix more and you can distribute into multiple barrows and get the job done quicker in the end, resulting ultimately in getting the mix down quicker which makes for a stronger bond, not weaker.

Mixing with a shovel on the floor is faster than mixing in a concrete mixer? You have got it bass-ackwards.
 

Givadogahome

Silver
Sep 27, 2011
4,397
2
0
Mixing with a shovel on the floor is faster than mixing in a concrete mixer? You have got it bass-ackwards.

You mix more and so is quicker. You can get down 4 X's what you can in a mixer. You have it wrong.
The longer it takes to get a mix down the weaker it is.
Mixers are slow, if you have a slab to get down then you get a truck and get it pumped in. If not accessible or simply prefer using cheaper labour get a couple of volcanoes on the go, you can turn over 6 + tonne an hour, easily, on a mixer you will be lucky to do 2 tonne. You do what you need to but the bottom line is your argument is nothing to do with stretching cement, ratio has nothing to do with it.
 
Last edited:

Bigocean

New member
Nov 25, 2010
255
2
0
Death by shovel.

You are seriously fast with a shovel! It takes a mixing machine having a capacity of 27 cubic feet or larger 1 1/2 minutes to mix a 1-cubic yard batch of concrete. Add another 15 seconds for each additional 1/2 cubic yard. And you can mix 4 times faster than that with a shovel on the ground, wow. And you said it is stronger as well?

Death by Shovel
 

Givadogahome

Silver
Sep 27, 2011
4,397
2
0
We can all Google, so I can see you have not a grasp on this yet. Let me try and simplify this for you. The quantity you can mix is much larger, mixers are restricted in size, and varying sizes and so where you managed to google these silly stats I'm puzzled (and in reality they are wrong), the mix is mixed dry on the ground before water is added, not that much backwork is done once water is added and so forget the vision of guys turning over constantly as if a machine, this is not needed. Mixing dry is light work and thorough. Now you can add water into the centre of the volcano, right up to the lip and leave for 10 minutes (the water is absorbed into the mix) while you prepare another, once the other is prepared you come back to the initial and cave the sides in and start turning over quick, a couple of shovels is good, then barrowed and off. Hopefully you can see a cycle that now occurs and it becomes much quicker.
As for shovelling, well, with a mixer you are shovelling from floor, to mixer, why not leave on the floor and use that energy to turn it over and get a better result.
The quicker you get a mix down the stronger it is, that is just a fact.
I am telling you onsite realities here, after 20 years property development throughout Europe and to European standards I know what saves time and works well. The problem with google is much of the time it is great on paper, but in reality is not that productive.
I'm not debating this with you, I'm simply telling you how onsite is. You can view from your computer screen and continue to clean mixers out for an hour before knocking off time, doing pi$$y little mixes, having guys standing around waiting for cement half the day, that is your choice, to get the same productivity hiring 3 or 4 guys and mixers more than needed, jees (there is always method to perceived madness, if you don't know, some things are difficult to understand, hopefully you understan a little more now).
I prefer to keep my guys moving, and therefor keep the mixes coming.

And by the way, give me a mixer that will toss out a mix every 1.5mins, that is BS and if it is doing that then it is not mixed properly.

I am not going to debate the mixing method as you have yours, and I know whats better so move on.

Tell me about stretching cement? How does the method adjust the ratio?
 

Chip

Platinum
Jul 25, 2007
16,772
429
0
Santiago
A couple of observations:

1. The structural concrete used here is mostly the type that takes days to cure and is generally placed in its forms in a matter of hours, whether done by pump or by hand.
2. The most important structural elements of a building are the footing, the columns, beams and floor and roof which are mostly poured into place in forms.
3. Concrete can only handle compressible loads while the steel handle the tensile loads.
4. Believe it or not proper engineering techniques are taught here in the DR to the design professionals. In fact this is the case for most university derived degrees I would suspect based on my personal observation.
5. Not being a structural expert but being somewhat familiar because of classes in college and some practical experience and living here in the DR and talking to engineers the main cause for building failures are:
a. Greed - engineer/developer decides to save money and choose inferior unproven materials like sand, specifies the min. size rebar and beams possible and uses the bare min. amount of cement needed to bind the concrete mix.
b. Maestro or engineer are incompetent or engineer doesn't surpervise maestro.
c. Foundation not explored correctly to find unsuitable structural soils(compressible) and thus remove them or doesn't correctly compact the structural fill as is standard practice.