Reinforced hollow block masonry 1

[Bamsi786]

thread507-474133
İ need some guidance about reinforced hollow blovk masonry, we are in a bit of a situation, my last thread was really helpful the people who replied there were really helpful, ill mention their names and ids, im facing a problem where the grouting in the reinforced cells were not done properly, and now im not sure what to do, locals are suggesting just to open the shell at the top, and center and pour concrete with smaller crush. Please i need help ¢

 

[Ingenuity]

General question - what sort of mix do they use for PT grout? I’ve seen lots of bags of cement on site for the PT guys, but I’m not sure the exact mix they use.

I’m in Australia.

In the old days in AU, it was site mixed grout with water/cement of 0.40, sometimes a cellulose-ether (MethoCel) was used (bleed reducer) and pumped with a rotor-stator pump. Real simple - until it wasn't!

I am going to guess that 90% of PT to building in AU today is still done with similar site-mixed grouts. For PT in bridges in AU I suspect that prebagged grouts are now the norm.

I (and probable rapt too) can tell you horror stories where numerous tendons on projects did not get grouted as the PT foreman sold the cement to the masons for a few cases of beer.

The rotor-stator pumps do NOT pump the pre-bagged SIKA, BASF etc PT grouts - you need high-shear colloidal mixing like the setup STrctPono shows above (that SD rig is a ChemGrout colloidal mixer and progressive cavity pump - looks like a CG-600).

For small voids in concrete/masonry/PT ducts, often vacuum grouting is used. Need to first locate the void, measure the volume (proprietary techniques available), then only 1 inlet is required to fill the void. Compared to positive pressure grouting, where you need 2 or more ports.

 

[Bamsi786]

Okay so another problem, here in my country there arent any grout pumps for rent, only concrete pumps,a stationery pump is available but im not sure if the wall can bear the pumps pressure, or thats not a problem, i found a grouting pump for sale but im not aure that can pump grout if i add crush to it, ill share the pics, please let me know whats the solution

 

[dik]

times have changed... I haven't been involved with masonry high rise for over 30 years. Grout used to be mixed in a wheelbarrow and placed from the next floor level using the in place HC slabs as a working platform a plywood 'board' was placed to reduce the 'splash' or overflow and the grout had a freefall of about 8'. I don't ever recall vibrators being used... slump was 8" or 9" as I recall and no SuperP.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Bamsi786]

Would a hand pumped grout pump work? Or would i need a motor one?

 

[STrctPono]

A manual pump would work so long as you feel comfortable hand pumping that much grout. You don't need a lot of pressure to properly make these repairs. I've seen contractors use hand pumps on small repairs, it's just painfully slow.

 

[Bamsi786]

And would a stationary concrete pumps throttle/pressure be too strong for my walls to handle?

 

[Bamsi786]

Hey guys, please let me know if my walls can bear the pressure of the stationary pump, cant use mobile pumps as the have to be used from the top and my slabs have been poured already, secondly there is another option let me know if that is advisable, i can chisel the whole block line vertically where the steel bar is, ill share the link, and then fill it with concrete manually, this is only in the case if a pump is too much for my walls. Secondly please define grout to be used in the cores, grout/concrete, i only used concrete maybe thats why it didnt went all the way down as it has crush/aggregate almost an inch thick, is grout just cement, sand and water? This time i was thinking of using very small crush we call chips here, with cement and sand to pour, my question is, what should be the grout made up from and what should the ratio be?

 

[Ingenuity]

That wall would be 'demolish and redo' if it was on one of my projects - and I am in the concrete repair and strengthening business.

Besides the voids to the CMU wall, the bond beam above has voids and was not consolidated (vibrated) sufficiently.

 

[Bamsi786]

Brother i appreciate your advice, but already too much capital invested,stuck in a huge problem, please keep in mind this project is in a very low seismic zone area, existing method of construction is double wythe 9inch brick load bearing walls with no columns or bond beams, i really need a solution as it is, i wish i would have stopped at my first floor but already im done with basement and ground floor slab, last slab left

 

[Bamsi786]

Just let me know what to use as grout to fill in these cores

 

[Bamsi786]

And its not just one wall, almost 80% of the voids with rebars are not filled due to concrete being stuck at the top and not falling all the way down. Finding a solution to fill them up now

 

[Tomfh]

i only used concrete maybe thats why it didnt went all the way down

You can't fill hollow walls with normal concrete. It's too stiff and will plug up the cores like has happened here.

You need core fill concrete mix when filling walls, which is a very fluid high-slump mix with smaller aggregate that can flow down the cores.

https://www.hanson.com.au/products/concrete/fills/coremasta/

If you are going to attempt to salvage these walls you need something very fluid.

 

[STrctPono]

Bamsi,

Are you an Engineer? Or are you a homeowner? You are asking some very basic questions that most Engineers should know the answer to. We don't fill CMU cells with concrete that contains 1" diameter aggregate for exactly the same reason you have found. CMU grout can either be a fine grout or a coarse grout but even with a coarse grout, you are still getting 85% of the aggregate passing a 3/8" dia. sieve size. The ready mix company should have had a CMU grout that they could have provided to you that was specifically intended for this. If you guys tried to save some money by buying a concrete which contains less cement then I guess that's on you.

The craftmanship of that CMU wall looks really bad, BTW. I would be finding a new mason.

What do you think is going to give first? The mason holding the end of a grout hose against the base of a CMU wall inlet port while you are pumping grout or the face shell of the block? My guess is that mason can't resist anymore than 3 psi of pressure. Core a bigger hole at the top if you are worried about building up too much pressure.

 

[Bamsi786]

Strctpono im the house owner, and we dont use blocks from where i am, therefore these stupid mistakes happened, do you have any contact where we can talk once? This posting and waiting leaves a communicatiin gap

 

[Bamsi786]

amc.abubakar@gmail.com

 

[Bamsi786]

And what about 2/8 inch aggregate? Wasnt saving any money for concrete, i didnt realize that the mix should be thinner, anyways, do i need 3/8 or 2/8 is also okay?

 

[dik]

3/8" agg is common.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Tomfh]

2/8 -3/8 inch is common, but please understand the agg size is just one factor. You need a different grout mix to make it flowable, not just smaller agg.

 

[Bamsi786]

By grout mix you mean cement sand and aggregate with water right? Their ratio?

 

[dik]

...as noted earlier, a high slump likely using super p... a specialty mix.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik