BUILD YOUR OWN HOME OR BUY READY BUILT

The guys started using red lead paint, it doesn't hurt but it is not required. This is per the ACI. When I originally posted pics from our house build it was quite a topic. Bottom line, if you are not losing area on the rebar a little rust is fine; if you want to paint them go for it, it doesn't hurt anything.

Not sure what you mean about the fish....

Shawn

 

Yes, I build for a living; vertical construction to include multi story concrete facilities to horizontal construction of roadways and airfield pavement. My last few projects have been on the fuels side that also had some concrete containment for aviation fuel tanks.

The stirrups were bent to the rebar plan signed off by a structural engineer; if you tie the stirrups you are fine and the 90s are easier to position and I honestly can't the degree bend of a stirrup effecting structural integrity.

I do enjoy using concrete as the building medium; a lot of fun until a form blows out.

Shawn

 

Interesting. First world countries banned lead based paints a long time ago.

I agree that rebar can be left bare in non marine environments. Well consolidated concrete seals it enough to reduce the availability of enough oxygen to support corrosion. I have seen extensive use of epoxy coated rebar in marine applications where the added corrosivity of salt water is a factor.

Many of your posts involve fishing in exotic places. I have become accustomed to these stories and expect your posts to have something to do with fish. Construction can be a bore.

 

Its left bare in Aust. Starts rusting on site.

 

It is called red lead…never paid attention if it was lead based, kinda doubt it contains lead but would not be surprised.

I’m in Guam at the moment, been out fishing twice and did not find it all that fun…trolling only means the guy (or gal) driving the boat needs to be skilled. I should be heading back to Korea in a few months so should be back to fishing next spring, both fresh and salt water.

Shawn

 

Research shows that a little rust is good. It creates a better friction grip between the concrete and the steel. Thick lose rust that can be easily knocked off is not so good.

The only problem arises when the concrete is subjected to constant water pressure, is overly porous, has bad cold joints or is immersed in seawater.

Constant water pressure. All typical concrete without additives has some porosity. This allows water to soak through it. Water carries some suspended free oxygen. This is what fish breath when they swim. This oxygen can react with the iron causing rust. The rust expands with great strength and spalls the concrete. This can happen where there is puddling or other situations that constantly pushes water through the concrete.

Excess porosity. Excess porosity is usually caused by mixing too much water with the concrete. A correct amount of water is needed for the cement to undergo a chemical process called hydration where the water reacts with the cement to form hydrates. Excess water forms water droplets within the concrete that does not react with the cement. Think of these as similar to air bubbles in the concrete. This causes the cured concrete to be more porous and increases the transmissibility of water through the concrete..

Bad cold joints allows the water to wick through the crack or porous area of the cold joint. It gets to the steel and the free oxygen within the water causes the steel to rust, expand and spall the concrete.

The solution is to use a minimal amount of water in the mix and consolidate the wet concrete with a concrete or form vibrator. (I have seen vibrators with long tails for pillars instead of form vibrators.) I have also seen bonding of cold joints with PVA or latex (they are both white liquid) in the cold joints in above water marine environments. PVA or latex has a better bond with cured concrete than wet concrete has with cured concrete.

Sadly this guy does not do destructive testing on his bonds. He does show four different techniques and discusses how in a previous video he wet the old concrete first before adding the fresh concrete.


Concrete bonding slurry with acrylic fortifier.


PVA Slurry

 

This Link tells you that you should not bond new concrete to old using PVA adhesives, I read this before but wanted to confirm it before saying anything, for years I am been using PVA for this purpose but now I know better. unfortunately this info is mainly concerned with Tiling but much the same rules apply as most tile adhesives are cement based.
Can I Use PVA to Prime A Surface Before Tiling? - Walls and Floors

 

Honestly I only remember that it was a white liquid. I am probably wrong now thinking it was PVA. It probably was an acrylic fortifier like the references below. It was painted on directly. Not mixed with the concrete. It was one of the main brands in the US like Sika or Quickcrete.

Here is a video of Quickcrete concrete bonding adhesive (acrylic fortifier) that is painted on directly or mixed in:


Here is the data sheet showing it is a acrylic fortifier.
https://www.quikrete.com/pdfs/data_sheet-concretebondingashesive-no9901-9902.pdf

Here is the SikaLatex product describing it as a acrylic fortifier. SikaLatex® R is an acrylic-polymer latex. Maybe latex and acrylic mean the same thing in this instance?
https://usa.sika.com/dms/getdocument.get/b3bbdb92-696f-47d7-b2de-3100c6384c5d/sikalatex_r.pdf

 

Anyway Skipjack, I know by now that most of what you post here is done in good faith, informative and without BS, I would go as far as to say we both read from the same page, except you read all the small print as well haha. Understand this, most additives available in the western world are just not available here, I think we all agree that cold joints must be avoided at all costs, the pics I posted at the beginning of this thread show a type of build method not uncommon here in the Philippines, this is perhaps the very worst example I have ever come across, the CHB is holding the Pillars and beams together? I would say that most of the homes built here with cosmetic skinny pillars are done in this way, they build CHB walls around 4ft high leaving a gap for the Pillar, the gap will contain a cage of sorts, that is then filled with concrete, then another few ft is done and the same again, so in this Pillar there will be 2 or 3 cold joints and for some very strange reason I have often noticed there will be one in the last 12'' at the top where it meets the Beam and yet it is the very top and bottom of the Pillars that suffer the most stresses, maybe that is where they make an adjustment for level?

CHB houses and the above mentioned methods employed here in which to build them are so inferior to anything else, if you could measure the PSI of each component used and average it out it would be very low, way lower than 1000PSI overall? add all the cold joints into the mix the lack of proper Lintels over doors and windows and what are you left with, A Lethal Weapon, at some point in their lifetime there is likely to be a more than moderate earthquake, these houses are going to fall and likely take the lives of some of the occupant's living in them.

If a house has to be built using Negative R value Cementitious material, the only way I can see to do it well is to make your own CHB you only need one big Fecker in the shape and size of a hoose.

 

I will agree to your suggestion to use Phenolic boards as it seems like I can purchase these in Duma, I will use PVC spacers as per Texas Filipino and have a question that you or Shawn might answer.
1. The wall will be 20 meters long and 8ft high so as to use complete forms (8x4) , if I lay the form sideways (so 2 levels 8 ft long by 4ft high) . do I tie in the 2nd section all the way below from the footing by long vertical rebar and should I make a small beam on top of the first section to tie in the second section as the second section will be a cold bond.