Cement wash coating for steel protection

[MikeJohns]

Does anyone know what to use for mixing a good protective alkaline cement wash for coating the insides of ships steel water tanks?

I've come across it many times in situ working well but never specified it. Some older vessels are coated inside extensively with a cement wash and are sweet and bright under the coating after many decades.

Could probably use a similar recipe to the ferro boatbuilding mix.

[DGreenwood]

I saw a fellow do the inside of his steel water tanks this way. They stayed like new and the water was clear and sweet. As I recall he used straight Portland (cement only, no aggragate) mixed to a thick paint consistency. I can't really remember him putting in any other ingredients???
I was impressed by the job it did.

[D'ARTOIS]

It is as DGreenwood says, save for an addition of ................I forgot, something to do with Sodium. I have the recepe somewhere, will look it up later in the day.
Come back on the issue later.

[MikeJohns]

D'Artois
I would have expected something like Silica Ash. The problem in seawater environments is to stop the chloride ions permeating the cement. The aditives do this.
I would be intersted to see what you come up with. This is "OLD Lore" now and seems to be mostly forgotten. Modern equivalents are available at a cost with fancy brand names but they don't tell you what they use. An old Iron sailing ship sat sunken in Tasmania for decades, when she was raised the plating was in good order where she had been cement washed. The cement was still in place and adhering well.

[D'ARTOIS]

Today I started to look in the attic where I store my files, but I couldn't find my notes that are in the manual I wrote lightyears ago for amateur builders.
I come back on it.

[D'ARTOIS]

Mike, I don't find the notes. But I remember - and that is easy to check for you - that it is the same stuff they use in Ferrocement.
The books where I have all those old recipe from is in my house in France.

[MikeJohns]

Thanks anyway Dartois I'll do a bit of experimentation.

[Nels Tomlinson]

D'Artois, were you thinking of sodium silicate? I have no idea if that's right; I'm just trying to jar your memory.

Nels

[phylus]

Hi, very interesting thread you've got going here.
Any progress with the missing secret ingrediant/additive for cement mix?
thanks
phil

[D'ARTOIS]

It is not secret, just missing for the moment. It is my other residence, in France,
so a bit far away for the moment.....

[DGreenwood]

D'artois
I think I might have just remembered...see if this jogs your memory. Calcium Chloride additive. I think it was 2% to accelerate the cure and act as a plasticizer. But I am unsure if I have the right chemical?

[SamSam]

I saw a fellow do the inside of his steel water tanks this way. They stayed like new and the water was clear and sweet. As I recall he used straight Portland (cement only, no aggragate) mixed to a thick paint consistency. I can't really remember him putting in any other ingredients???
I was impressed by the job it did.

How do you apply the stuff? There is a latex based additive that is used in stucco that makes it stick better to old work, available at Home Depot, perhaps that would work. Was this concoction used only in water tanks, or over the whole interior?

[MikeJohns]

I am still a long way from having a firm recipe that I could specify for a mix-your-own cement wash. Maybe when Dartois gets back to his summer residence!


Some material I have from the pertland cement association may be interesting:

Cement wash protects steel from corrosion through its highly alkaline nature. The high pH environment in the cement (usually greater than 12.5) causes a passive and noncorroding protective oxide film to form on steel. However, the presence of chloride ions from seawater can penetrate the film. Once the chloride corrosion threshold (about 0.15% water-soluble chloride by mass of cement) is reached, an electric cell is formed on the steel and the electrochemical process of corrosion begins. Once it starts, the rate of steel corrosion is influenced by the concrete's electrical resistivity, moisture content, and the rate at which oxygen migrates through the concrete to the steel. Chloride ions alone can also penetrate the passive film on the steel; they combine with iron ions to form a soluble iron chloride complex that carries the iron into the cement coating where it can later oxidise expanding and cracking the cement coating.

The resistance of cement based morter to chloride is good; however, it can be increased by using a low water-cementing materials ratio, and supplementary cementing materials, such as silica fume, to reduce permeability. Increasing the concrete cover over the steel also helps slow down the migration of chlorides. Other methods of reducing chloride ingress include the use of corrosion inhibiting admixtures commercially available from a variety of manufacturers.

Another approach is surface treatment to stop or reduce chloride ion penetration at the cement surface. Silanes, siloxanes, methacrylates, epoxies, and other materials are used as surface treatments.

Reference :
Portland Cement Association;
Kerkhoff, Guide to Protective Treatments, 2001, 36 pages.



And a commercial addmix from Tapcrete:

TAPECRETE MARINE COATING
It is a three component water-based coating containing a liquid blend, portland cement and fine silica sand all supplied in requisite proportions. Bonds well with mild steel and galvanised steel. Provides corrosion resisting coatings to steel structures in sea or fresh water, salt spray on environment, suitable for bridge decks, ship docks, ballast tank for ships, steel water mains, pipings and other above grade and subgrade tanks. Correct surface preparation is important for the performance of coating. The surface to be treated should be properly cleaned to remove all deleterious materials. After mixing the component materials in paddle type mixer at site, the resulting creamy slurry of thick paint consistency can be applied with roller, brooms, brushes or air operated spray system to build up the desired thickness. Air cure for about 3 days for normal case and water cure for about 3 days when the structure treated is subjected to continuous water exposure. One cubic meter of Marine coating required the following
Marine Coating 446 kg
Portland Cement 858 kg
Fine silica sand 858 kg
For a 2mm thickness of coating the requirement will be about 4 kg of the three component Marine Coating/ per sq. mtr.The generally applicable thickness ranges from 0.8 to 1.0 mm. The corresponding requirement can be worked out from the 2 mm thickness value.

Of course Tapcrete don't divulge the admix content. The ferro boat building literature talks about Pozolan and I am not sure what that is either.

[D'ARTOIS]

I believe indeed it was Calcium Chloride; however I am not sure about it. I am stuck but again, t could be calcium chloride.

[DGreenwood]

Interesting ...
From the article above it seems that silica is the answer. It looks like chlorides may not be such a good thing??
I would love to find out the method as I also have an immediate use for it.

[cyclops]

Would a construction company who does any type of metal construction in salt or fresh water have a Engineer that would know? Pure Portland Cement and water is very very water proof. Look at bridge piers.

[MikeJohns]

Ferro cement yacht hulls include Pozzolan to make the plaster less permeable.

siliceous pozzolans react with the non-cementitious calcium hydroxide in the hydrated cement paste to produce (highly cementitous) calcium silicate hydrates, yielding higher strength and dramatically reduced permeability.

A "pozzolan" is defined as "a siliceous or siliceous and aluminous material which in itself possesses little or no cementing property, but will in a finely divided form and in the presence of moisture chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties


Cementitious and pozzolanic materials

High-calcium fly ash (class C)
HCFA is the residue collected from the smokestacks of coal-fired power plants generally using lignite and subbituminous coals. Class C fly ashes are in themselves mildly cementitious, and have been combined with lime or even calcium carbonate soils to produce moderately strong concretes.

Ground Granulated Blast Furnace Slag
GGBFS is the ground residue from iron smelters, and is also mildly cementitious in itself, but hugely pozzolanic in combination with water and cement.

2. Highly active pozzolans

Condensed Silica Fume
CSF is a waste product of the silicon metal industry, and is a super-fine powder of almost pure amorphous silica. Though difficult (and expensive) to handle, transport, and mix, it has become the chosen favorite for very high-strength concretes (such as for high rise buildings), often in combination with both cement and fly ash.

3. Natural sources
Pozzolans are present on earth's surface such as diatomaceous earth, volcanic ash, opaline shale, pumicite, and tuff. These materials require further processing such as calcining, grinding, drying, etc

______________

So we want a chemical that turns the calcium hydroxide into a calcium silicate hydrate.

[safewalrus]

As a (old?) Merchant Seaman we used to coat our fresh water tanks annually with a cement 'wash' made up of Portland cement - NO secret Ingedient! mixed with water to a thick mess, 'bout the consistency of porridge and applied it using soft brooms. Let it dry and washed out the tanks by filling once then refilling for use. Sweet as you'd ever get - not like modern composites which seem to fail frequently! Or maybe it was because we were not so sophisticated in those days!

[D'ARTOIS]

I have asked my sister to look in my files that are in France.....Although she breeds horses and know bl***y nothing about boats exept to get seasick in no time...........

[Riley]

Aloha, Sorry to bud into your forum, but it is important for me to let the world know that my late father, Victor Riley, invented Tapecrete. Through devious business practice, his graduate student's family continues to profit from his genius. They took away the money, but they can't take away my father's legacy. Please spread the word that Victor Riley is the true inventor of Tapecrete. Victor, a mensa member and civil engineer, was an avid boater and rower, as are all of his children. Born into poverty, he worked in mines in northern Canada to put himself through university and eventually graduated from Cambridge University with a PhD as an Athlone Fellow. He used Tapecrete for everything. In the early days, the UofT's faculty thought he was nuts when he built a racing canoe out of what they thought was concrete. I loved hearing my dad tell the story of how he won the race with his "concrete canoe". He even built us a 2-story playhouse out of the magical stuff. Please help spread the word that Victor Riley invented Tapecrete.
Thanks heaps! :D

[JimCooper]

Alas another wronged man. Sorry to hear it.

Perhaps you can remember what he had in the shed then we can reproduce this admix ourselves and shaft the thieves and pirates who stole the recipe !

Dartois

did your wee sister ever come up with that paprer you had the recipe on ? I want to use a brew on my brothers boat.

Jim

[D'ARTOIS]

After so many time, I have found the recipe. Mike, please consider that this recipe dates back to 1936 when it was published for the first time. later on, in a more recent publication 1953, the recipe was repeated, unchanged.

Use as an method of application to/on an already existing coating:
Nafta......................100dl
Aluminium Stearate.... 10dl
Icevinegar........0,3 - 0,5dl

The nafta should be pre-heated till 80 deg. Celsius and than one dissolves the alu stearate in the hot nafta.
After the stearate has been dissolved well, one ad the Ice vinegar or Ice acid to the solution under well stirring.
One gets a transparent viscous solution.

For direct application to the unfinished cement, one ads the aluminium stearate direct to the dry cement, about 100 till 200 gram per bag of cement.

The first recipe is for coating the already applicated cement.
You may also use ammonium stearate for the same purpose.

Hopefully, this brings you somewhere.

Regs
Brien

[MarkC]

Nafta is parafin wax or kerosene? Nafta is an American term?

Icevinegar is ?????

Ahhhhh - the terminology of the 1930's

All we need now is some 'Paris Green'!

Is the Aluminium Stearate safe to hold water?

Just curious.

[JimCooper]

After so many time, I have found the recipe.
...................
For direct application to the unfinished cement, one ads the aluminium stearate direct to the dry cement, about 100 till 200 gram per bag of cement.



D'Artois

I have an immediate application for this when I've finished my welding!
Would like a bit more help please.

You add 200grams to What size bags of cement? 40kg ?

Then mix with washed beach sand say 3 sand to one of cement with the Aluminium Stearate added to the cement.

Does this sound about right for filling in the bottom of my bilges ??

Thanks
Jim

[D'ARTOIS]

Yes, the recipe says so - between 100 and 200 gram per bag of 40 kgs dry cement without the sand.

Yes, one to three mixture is ok; the cement wash is also an excellent rust-preventer. In the old days it was applied to the bilges of the commercial barges that travelled the Dutch waterways. It was also used as a way of internal ballast. You can treat it afterwards with part no one of the recipe.

Good Luck!

[jglassman]

After so many time, I have found the recipe. Mike, please consider that this recipe dates back to 1936 when it was published for the first time. later on, in a more recent publication 1953, the recipe was repeated, unchanged.

Use as an method of application to/on an already existing coating:
Nafta......................100dl
Aluminium Stearate.... 10dl
Icevinegar........0,3 - 0,5dl

The nafta should be pre-heated till 80 deg. Celsius and than one dissolves the alu stearate in the hot nafta.
After the stearate has been dissolved well, one ad the Ice vinegar or Ice acid to the solution under well stirring.
One gets a transparent viscous solution.

For direct application to the unfinished cement, one ads the aluminium stearate direct to the dry cement, about 100 till 200 gram per bag of cement.

The first recipe is for coating the already applicated cement.
You may also use ammonium stearate for the same purpose.

Hopefully, this brings you somewhere.

Regs
Brien

A little help: what are the units/mix ratios mentioned above? Is dl a deciliter? Is this per 100lb bag of cement?

[Brent Swain]

All embeded material we made for embeding in cement in the steel fabricating industry specified that the steel be allowed to rust slightly, to ensure better adhesion of the cement.
Brent

[LyndonJ]

Why does Bruce Roberts claim that cement makes a steel boat corrode ? He says this in his book on metal boat building. Yet Ive seen ships cement washed that sat on the sea bed for years and the steel was as good as new under the cement.

[MikeJohns]

I think this is based on the problem that large blocks of 'stiff' poured concrete particulalry in high slamming areas tend to separate from the 'elastic' steel. Water gets trapped in the interface. A little rust then pushes the steel further from the concrete. Anchor lockers in particular suffer.

[druid]

We manufacture and coat large diameter steel pipes. For drinking water supply systems, the cement internal lining is specified in accordance with AWWA C205. Allowable cement type and sand/cement ratio is mentioned therein.

On the other hand, solvent free epoxies suitable for drinking water are much more effective for lining of steel surfaces.

[lazeyjack]

mike thanks for the package
why dont you apProach an employee of TAPCRETE, :)) The NZ navy use international tank liner which is an exp paint, you would think this cement recipe would have stood test of time, just because of the cost factor alone
nice thread
come to think of it, when they repair concrete water tanks they use some sort of wash, and i have seen sikaflex deliver bags of some sorta powder to the manufacturer of these tanks
The lining is composed of commercial grade silica aggregate of 100-mesh and 325-mesh particle size, a cementitious binder material, calcium hydroxide, water repellents, and hygroscopic salts. The materials, when combined and mixed with water make a low soluble material which has when set, a coefficient of thermal expansion approximately equal to that of steel The materials when mixed with water form a plastic mixture showing no unwetted parts.

The materials do not contaminate hot or cold water with odors or toxic matter and contain no greases, resins, stearate, stearic acid derivative, sand, mica or pumice. Materials that will deteriorate when continually immersed in hot or cold potable water under the normal pressures maintained in public utilities are not used. The materials have a weight loss less than 4.0 percent after being immersed in a carbon dioxide solution for a continuous period of 72 hours.

Galvanized steel mesh is attached to the inside surfaces of the tank to ensure proper adhesion of the lining. The lining material is applied in two coats with a stiff brush, trowel or other hand tool. The first coat is not less than 0.125" thick and the second coat is 0.375" thick to provide uniform thickness of 0.50" thick. The first coat is thinned to the consistency of heavy cream and applied with a stiff brush. The first coat is cured sufficiently to insure bond with the tank steel surfaces but not allowed to dry out to affect the quality of the bond between the two coats of lining. The lining material is cured and adheres firmly to and covers the interior of the tank.

The joint between the lining and tank at the taps is sealed to prevent corrosion behind the lining. Only enough siliceous material is mixed at one time that can be applied and finished in 30 minutes. No tempering of mixture with water is permitted. Immediately after the application of the lining material, all openings of the tank are closed and secured by pressure sealing and the tank allowed to stand without water for a minimum of 24 hours. Drying or curing of the lining by a fan or other forced methods is not permitted. The water absorption of the lining is not more than 17 percent of the dry weight.

On Hanson cement lined vessels, FNPT connections are all 3000# couplings, with 304 stainless steel highly recommended at extra cost. Flange and heater collars can be cement lined or made of 304 stainless steel. All openings are closed or plugged during storage and shipment.

Thickness:


0.5" to 0.75" (over welded mesh)

Weight:


6.00 lbs/sq ft

Max. Temp:


210ºF