BajaNomad - TO COMPACT BY MACHINE OR TO TAMP BY HAND?

TO COMPACT BY MACHINE OR TO TAMP BY HAND?

amir - 1-9-2008 at 05:35 PM

We are at the stage of filling with dirt the inside of lthe footings and foundation of our home. In places it is about 65 centimeters above ground.

Originally we were told that it will be compacted by machine.
Now they are doing it but they are using a tamper. The builder says "I've done it like this many times."

Shoud we insist on using a machine for compacting?

We are not on loose soil or sand, but we wonder.
Any input or suggestions will be greatly appreciated.

[Edited on 1-10-2008 by amir]

DENNIS - 1-9-2008 at 05:55 PM

Amir....

What is it that you're calling a tamper?

Russ - 1-9-2008 at 06:06 PM

I believe that a machine is better but either way it would be best the compact only a few inches at a time and damp soil would be better. Best of luck with your new building.... and contractor. Other than dealing with PROFEPA building was the most frustrating thing I've done down here.

amir - 1-9-2008 at 06:27 PM

Quote:

Originally posted by DENNIS
Amir....

What is it that you're calling a tamper?

Dennis,

The tamper is a block of iron about 10x10 inches square and maybe 1/2 inch thick or so with a wooden handle. They are filling in layers of dirt that appears to be damp, and then they tamp with this tool.

I offered the whole crew free adjustments while they work here, and they joked that doing the compacting by hand this way, they would get more adjustments. The youngest son joked that the father (el jefe) wants them all to get strong. And indeed they are using a lot of muscle power to do this work.

longlegsinlapaz - 1-9-2008 at 06:58 PM

Russ is right...it appears to me that your builder's cutting corners & increasing his profit by tamping rather than renting a compacting machine. For that depth, you can get a 90-95% compaction rate if you make him stick to his original commitment of using the machine. He probably included the rental cost of the machine in your bid since he told you that's how it'd be done originally.

Even with the machine, make sure they only compact 2-3 inches at a time & keep each layer wet as they work. The machine is a lot heavier, it compacts with more force than the tamper, and it is more consistent since it doesn't get tired! :bounce:

Russ is also totally correct re PROFECO! :lol:

amir - 1-9-2008 at 07:13 PM

Quote:

Originally posted by longlegsinlapaz
Russ is right...it appears to me that your builder's cutting corners & increasing his profit by tamping rather than renting a compacting machine. For that depth, you can get a 90-95% compaction rate if you make him stick to his original commitment of using the machine. He probably included the rental cost of the machine in your bid since he told you that's how it'd be done originally.

Even with the machine, make sure they only compact 2-3 inches at a time & keep each layer wet as they work. The machine is a lot heavier, it compacts with more force than the tamper, and it is more consistent since it doesn't get tired! :bounce:

Russ is also totally correct re PROFECO! :lol:

longlegs,

The compacting was NOT included in the original bid. Originally the footings were going to be buried deeper, but because of a small arroyo, we decided to build the foundation higher. I understood that this modification will require several truckloads of fill dirt and labor in compacting it. This family (from La Paz) is totally honest and I will be charged only for what they do. I am not worried that they are trying to cheat us; we just don't want problems with the floor later... What I will tell him tomorrow when they resume, is that the dirt should be wetted between the layers they are compacting by hand; the dirt is damp, but they have not been adding water.

He also said that they will use a "malla" when they pour the floor, and that will keep the floor from buckling and cracking.

Are there different sizes and strengths of malla?

DENNIS - 1-9-2008 at 07:26 PM

Amir...

Damp is good but, don't insist on Wet. They can't be doing this in the mud. Is there an equipment rental in your area? Have them get the proper tool. Compaction is important. How many square feet are involved?
I know what a tamp is...just didn't know if we were on the same page. You'll have cracks in your concrete if it's not on a firm foundation and tamping is better than nothing. Just don't let them get away with doing nothing.

Al G - 1-9-2008 at 07:34 PM

LLL is correct there is no way to compact 65 CM (over 2 feet) by hand without major settlement later...

DENNIS - 1-9-2008 at 07:41 PM

Quote:

Originally posted by longlegsinlapaz
Even with the machine, make sure they only compact 2-3 inches at a time

longlegsinlapaz - 1-9-2008 at 07:45 PM

I stand corrected on you're builder's potential motives! But I stick by my experience of compacted soil versus tamped. Tamping is okay for really shallow areas, but under your casa & outside the foundations, I'd opt for the compacting machine...if it's compacted 90-95% and you use malla there is no reason the soil under the casa should "buckle & crack". Yes, there are several different grades of malla...different gauges & the heavier the gauge typically the larger the grid. Different sizes for different applications. I'd also recommend, if he's not already doing it, that they fumigate for termites several times in the fill & compaction process, and definitely the surface area before they pour the footings, foundation & floors.

Al G - 1-9-2008 at 07:58 PM

malla...is that slab wire cloth that must be used anyway even with compaction grade fill.

Man or Machine

BAJACAT - 1-9-2008 at 08:25 PM

Amir if you can rent A Wacker, from any local company,it will be better.With the Wacker they can do six inch lifts,and get better compacction off course with good moisture in the filling material.By hand the lifts are going to be smaller,maybe two inches, but the force of the Tamper will vary with the different people that will be helping, this system works if you do it right.Ither way, when their done drive a metal stake with a slegde hammer in the ground.,with 90 or 95 % compacction it will be hard to drive it in, if it's to soft the metal stake will go in with easse , and it will required more work, unless you can hire somebody with a Gauge and have a proper test done..

amir - 1-9-2008 at 08:39 PM

Thank you all, so far, for your input. We'll be mulling this over overnight. I hope I can get some sleep. I'll have to face the builder early in the morning with an answer, as it all is going very fast...

longlegs: about the fumigation, this subject was never discussed. My question is, how long are the chemicals active? Even if it was thoroughly fumigated as you recommend, what would keep termite infestations from appearing later, say 2 years, or 5 years, or whatever the life of the chemicals was?

longlegsinlapaz - 1-9-2008 at 08:45 PM

Quote:

Originally posted by Al G
malla...is that slab wire cloth that must be used anyway even with compaction grade fill.

Not sure what you're referring to. Never seen anything like that here, there is nothing but dirt or tierra colorado used locally....depending on the depth of the fill/compaction, typically held in place with retaining walls. No cloth involved. Locally, they even call chicken wire malla....albeit the lightest grade! It's simply a grid of heavy gauge wire that helps prevent the cement from settling or getting major cracks. It starts out at the bottom of a pour area, but they use a metal hook to lift it so it's closer to the mid-depth when the cement hardens.

I have lots of pics, but don't have a reduction program to post them!

amir - 1-9-2008 at 08:51 PM

longlegs, you are a wealth of information! Thank you.
What chemical, brand, do you specifically recommend for the fumigation, and where is this available in La Paz?

longlegsinlapaz - 1-9-2008 at 08:56 PM

Amir, they most likely WILL appear later, that's the nature of the tenacious termites here! But they do sell a product that's guaranteed for 7 (maybe 8...I forgot!) years. If you kill the total existing population in the soil, it reduces the future generations from being born in "the old neighborhood"! It seems to have a longer lasting effect in the soil to keep them from coming in through cement that it does where wood is involved....in my personal experience. Spray your foundations & a swath of soil all the way around your casa every few years to help minimize re-infestations.

Mango - 1-9-2008 at 09:03 PM

The machine will be best to compact the soil; especially if it is a two story house since each footing will have to bear more weight than a one story home.

Either way, the house won't fall down because of non compacted soil. You will just develop cracks in the foundation/walls and tiles due to settlement down the road. Cracks don't look pretty but they are not dangerous in most cases.

longlegsinlapaz - 1-9-2008 at 09:06 PM

I'm cheating.....I cut 'n pasted this from a U2U I sent someone else recently...

What I currently have on hand is a product called "TermiDel 48". In my experience, all of the termite products you can get at places who specialize in exterminator-type products works well.

There are several places in La Paz...I'm sorry, but I can't remember exactly WHERE the place in town I got it is!! My most recent purchase was from a place in Chametla a block off the airport road...5-6 blocks off the hwy (Sorry!! There aren't an overabundance of street signs in Chametla! :lol:

)

If you can find exactly where they're coming through the concrete, get a needle (like for insulin injections @ any farmacia) and inject the stuff as deep into the hole as possible. When I put it inside the walls, I don't dilute it. If I paint it on wood, I do dilute it. You can also dilute it & spray it on outside foundations & a swath around the outside of the house. I spray the tunnels inside to kill anything inside & let them dry before I clean the tunnels off the wall/floor. This stuff is really potent & smells obnoxious...be careful to keep animals away from it until it dries & don't use in an enclosed area if you have birds!

capt. mike - 1-10-2008 at 06:21 AM

the largest const defect litigation suits and ins claims on record in the most litigous state in the union.........California....one in Santa Monica which also involved the largest bond failure ever at $40 million - were all about soils subsidence.

as a builder and developer who rapes the land and desert regularly.......let me tell youn where NOT to cut corners.......compaction. Especially under any supportive foundations. and don't forget problems associated with expansive soils conditions. If you have any clayey materials native or imported watch out for drainage in proximity to concrete!!!

mtgoat666 - 1-10-2008 at 09:33 AM

Quote:

Originally posted by amir

Shoud we insist on using a machine for compacting?

[Edited on 1-10-2008 by amir]

Hand-compacting is common in Mexico (and common in any country where equipment is rare and labor is cheap), and works fine if done correctly. You could ask the contractor to certify the soil compaction is >95 density (and absent expansive soil) via soil testing. Maybe ask your engineer or architect to observe and test/certify your contractor's soil prep work. If you insist on the contractor using a mechanical compactor, you may be asking your contractor to get on the job training using equipment they are unfamiliar with.

mtgoat666 - 1-10-2008 at 09:37 AM

Ignore the prior advice to keep the soil wet. You want it damp, at optimum moisture content, Wet soil cannot be compacted.

Al G - 1-10-2008 at 10:08 AM

Quote:

Originally posted by longlegsinlapaz

Quote:

Originally posted by Al G
malla...is that slab wire cloth that must be used anyway even with compaction grade fill.

LLL....

I can tell from your comments Malla is wire cloth...it is a construction term used to describe welded wire in a grid pattern...and yes chicken wire can be called wire cloth although it is not welded.

Al G - 1-10-2008 at 10:43 AM

The site I am on now...progress stage. This is not wire cloth just rebar. posting is to show Visquine. Cheap insect control as well as moisture...

[Edited on 1-10-2008 by Al G]

wirecloth.JPG - 38kB

Al G - 1-10-2008 at 10:53 AM

Just for info

wirecloth2.JPG - 38kB

Bajabus - 1-10-2008 at 11:00 AM

Re-bar or mesh in a slab needs to be located in the lower one 3rd or 1/4 of the slab. Pulling it into the middle makes it virtually useless unless all you want to do is hold the cracked pieces together.

Thats why on US construction sites you see them use little feet to hold the mesh at just the right height. Then they Carefully pour and vibrate the cement. They also do a slump test on every mixed load.

In Mexico the cement mix tends to be watery, sandy, they step all over the mesh and generally cavort about like drunken sailors while doing the pour.....Be especially wary of them damaging any conduit or pipes in the slab. Theoretically there should be none. they should be in the compacted soil below the slab and there should be a can or similar placed around the pipe where it comes up out of the slab so there is not contact with the cement...Theoretically at least.

You need to keep a very close eye on them during this entire process and not be bashfull about voicing your concerns when you see something that is not right.

Notice also the plastic vapor barrier in the photo

[Edited on 10-1-2008 by Bajabus]

amir - 1-10-2008 at 05:14 PM

Thank you everyone for your advise. The dirt fill is right now being compacted by MACHINE; they are keeping it damp, and they are using Termidel-48 between layers of ~ 7 centimeters rather than ~ 15 like when they had started tamping by hand.
The only one machine in Todos Santos available for rental was not going to be available until next Monday, so el jefe went to La Paz this morning and brought one down. The crew sat idle this morning waiting for the machine, but hey, why ask you guys advise if we are not going to follow it...

Thanks everyone, again. Will be posting and asking more questions as the next emergency arises. Stay tuned...

Al G - 1-10-2008 at 06:23 PM

Will try to post how a slab is prepped...if anyone cares...progress through the day today..

EDIT: well that didn't work
Edit: all said over 50 kb??? all under 45 kb on my machine will try again shortly...

[Edited on 1-11-2008 by Al G]

Al G - 1-10-2008 at 06:36 PM

Here we go again...at 38kb

Edit: you guessed it...last one first :lol:

[Edited on 1-11-2008 by Al G]

Slab pour 010 722x300.JPG - 46kB

Al G - 1-10-2008 at 06:43 PM

Should have been first

Edit: I hope it is 5:00 pm somewhere...hard to do without a pacifico :lol:

I quit...that was so blurry I feel I had too many Pacificos...never happen :lol:

[Edited on 1-11-2008 by Al G]

Slab pour 008 722x300.JPG - 44kB

Al G - 1-10-2008 at 06:51 PM

Someone could make a fortune teaching dummies like me to post quality photos...

Slab pour 009 722x300.JPG - 36kB

amir - 1-10-2008 at 08:04 PM

Al G,

I taught my crew to use a compacting machine and to use termite insecticide in the backfill.

I doubt it I could teach them to score a cement slab... :lol:

p.s. What are those white spots on the slab?

Al G - 1-10-2008 at 08:10 PM

The grid is the rebar before the pour...
the white spots :lol:

are spacer blocks to hold the rebar at the correct height through the pour...

Al G - 1-10-2008 at 08:20 PM

What you think is concrete, is sand over visquine.
First the visquine then the rebar...then 3"... 1/4" fill, then when fill is is leveled they pull the rebar through the fill and place 3" blocks into sand to get the rebar 2" high above the fill in a 6" slab. We pour tomorrow unless it pours (Rain).

Bajabus - 1-10-2008 at 08:29 PM

Nice pictures Al...I can't stress enough the importance of having the rebar or malla in the right spot. 2" off the bottom of a 6" slab is perfect. All too often the Malla used in common construction in Mexico is unrolled and all sorts of wavy before they start to pour. Then going around with hooks to pull just makes a mess. In some spots it ends up near the top, in other near the middle and in the rest near the bottom against the dirt. Plus they are wearing boots and stepping around in it while they go back and vibrate ( if they vibrate ). I cringe at some of the things I have seen.

Note that there are crews that take the time to do it right, just not very many