nigeriancuban:
nope,8 headpan of sand n likewise for gravel....

nigeriancuban:
nope,8 headpan of sand n likewise for gravel....

nigeriancuban:
nope,8 headpan of sand n likewise for gravel....

DonClerg:
What are the dangers of not using a vibrating machine.
The decking has no much beams. Beams are not more than 3m with Y16 top and bottom. Is it safe to cast it without the vibrating machine? Will there be risk of collapse?

jejeman:
Pls does a room size of 3.35m by 4.23m needs a beam across it centre apart from the beam on the surrounding wall?

olumide4christ:


Vibrating machine is important because it removes air bubbles from the concrete, hence allowing the concrete to consolidate.

opalu:


Correct explanations
Thanks.

olumide4christ:


Vibrating machine is important because it removes air bubbles from the concrete, hence allowing the concrete to consolidate.

johnson232:

how is the machine like?
is it mixer?

mufutau55:


Sucks air bubbles out of concrete works... used mostly on deckings and foundation DPC.
See below:

Hajji M.

johnson232:

God bless u sir.
but is like most engineers don't use it often.

opalu:
Keep your questions coming

Adek15:
pls can you explain to me concrete ratio mixture in details?

opalu:


You and Hajji M have already given the right explanations. The Poker Vi.brat.or should be used in every concrete work. So many builders don't like to use it for columns and slabs and lintels. That is not good. Usually the intersection btw columns and beam and slabs have internal gaps that tapping or any other primitive method won't solve

DonClerg:
Thank you very much.
1) Please how can one correct the errors in the images I sent?
2) Can it lead to the collapse of the building?
3) Can a slab with a very large area be partitioned with 9" blocks? The slab has Ly = 8.5 and Lx = 4.6. The slab was designed with Y12@ 200mm c/c both ways with a 150mm heigh. The contractor passed two internal beams(2Y16 T&B) at d middle of the Ly and Lx sides.
Will it hold if 9" blocks are used to partition rooms on it with a passage at one side?

opalu:


1. I couldn't see the pictured properly so I do not really know what to say. Maybe if you send me pictures taken of the under of the slab and the columns I can say the corrections better.
2. Buildings do not always collapse due to such things except they are serious issues. However such negligence on the part of the artisans or the owner will definitely shorten the effective lifespan of the building and also result in cracks over time. But like I said it is when I get a clearer view of other structural elements that I can say categorically.
3. Secret beam is not efficient when the span is too long. I have explained before using a ruler as example. If you bend the ruler holding it when it is flat it bends easily. But Try to bend the ruler when held at the edge side and you find that it is not easy to bend.
What it means is that the secret/hidden beam and normal beam all require depth. The deeper the beam (effective depth), the stronger.
It is for this fact that secret beams are used when the span is short. Those who use secret/hidden/inner beams for long spans do not really have the grasp of the engineering behind it. With all due respects.

You want to demarcate the slab on top of the slab or under the slab? If it up, it will depend on the grade of concrete you used. The mix ratio. If it's standard 1:2:4, then you would have used 175mm or 200mm thick concrete to be on a safer side especially if you are using mallams to do the casting.
With a strong mix and proper casting, you can use 9 inches blocks to partition.

From my experience, i discovered that each case is different and the problems and solutions are different.

DonClerg:
The rough structural members

mufutau55:


A good Engineer/Builder will surely use it.
In the old days, they just use ordinary iron bar to poke the concrete but not very effective like the "V-i-b-r-a-t-o-r".

Hajji M.

johnson232:

sir is the vibrator the samething with concrete poker?
cc: opalu

johnson232:

my brother what is the problem?
the structural design look okay..

mufutau55:

Yes. It is the same. The Nairaland software will change the name from Vib-rator to Romance automatically.
So Yes, they are the same.

Hajji M.

DonClerg:
can I use 9" block to partition the slab?

johnson232:

thanks alot sir.
but how come u know everything.

johnson232:
u can use 9inch block. if the sketch u posted was followed. have u done the partition already?

opalu:


Concrete mix ratio is the ratio between the 3 component materials that make up the concrete. These materials are Cement:SharpSand:Granite.
So if we say concrete mix 1:2:4 what we mean is that for 1 measure of Cement, you mix 2 measures of Sharp sand and you add 4 measures of Granite.

Mix ratio works only if you are using the SAME container to do the measure. What I mean is that if you are using the paint rubber to mix, use the same paint rubber for everything. If you are using headpans use it for all the 3 different materials. If it is full wheel Barrow that you use to measure the 1 cement, use 2 wheel BARROW to measure sharp sand and 4 wheel barrows for granite. If you change the measure then you are not getting the strength required of that particular concrete grade (mix).
I decided to attach this analysis table to explain more. However it's not a perfect representation of what is in my heart but it's near-perfect