Curing Agent for Concrete 2

[asixth]

What does everyone specify as a curing agent for concrete. I have been calling up lyndon's multicure AC90 however the guys on-site tell me that lyndon's no longer makes this product and it is now called lyndon's multicure AC.

I gave lyndon's a call myself and they said that the curing agent that they manufacture is lyndon's multicure R

 

[rowingengineer]

never get that detailed in my spec, unless I am with 50m of the sea.

An expert is a man who has made all the mistakes which can be made in a very narrow field

 

[asixth]

RE

Can you please elaborate on why you don't specify a curing agent unless you are within 50m of the sea?

I have been specifying curing agents on both drawings and specifications.

The note on the drawing reads:

Curing. After pouring and until final trowel all exposed surfaces are to be sprayed with aliphatic alcohol in accordance with the manufacturer's instructions. Within one hour of final trowel, apply the final curing compound "Multicure AC90", supplied by Lyndon Agencies.

And likewise the specification reads:

Curing Compounds
Standard: To AS 3799.

Final Curing Compound: Final Curing Compound is to be Multicure AC90 (supplied by Lyndon Agencies) applied strictly in accordance with the manufacturers instructions.

 

[hokie66]

Correct me if I'm wrong, but I think Lyndon's is a supplier/distributor, not a manufacturer. The products are made by someone else, and can be obtained from a variety of sources. The Multicure AC90 seems to be a product of Concord Industrial Coatings.

http://www.concordcoatings.com.au/

Any curing compound with the letters AC is likely an acrylic formulation, and these have been historically largely ineffective in curing. This coating may be an exception. If a product does comply with the 90% retention requirements of AS3799, the manufacturer should be able to prove it.

 

[asixth]

Thanks

Lyndons provided me with a Tech sheet on their Multicure R which says that it Passes AS3799, as well as providing a complience certificate for a product called RFA Multicure R which maintains more than 90% water retention as per AS3799.

Appendix B of AS3799 describes that the minimum water retention is 90% for complience with the code. I have specified that the curing compound is to comply with AS3799 so as long as the alternate product has a complience certificate to show that it complies with AS3799 there should be no drama.

Silly questions which I could probably find out myself with some research but will post here anyway:

1. Why are curing compounds applied to exposed surfaces? and
2. What are the advantages/disadvantages of using a resin based, waxed based, bitumen and acrylic based curing compound and where would each compound be used?

 

[hokie66]

1. Curing compounds are one option in curing concrete. There are others. I trust you are not asking whether concrete needs to be cured.

2. The better curing compounds for the concrete's sake are the wax emulsion and chlorinated rubber types, but these are difficult to remove if applied surface finishes are to follow. There also may be some health and safety issues with the chlorinated rubber. I am not familiar with the properties of resin based products, and have not heard of bitumen based curing. Acrylic based compounds have normally been PVA (polyvinyl acetate), which are not effective, but there may be later acrylic formulations which are better.

 

[rowingengineer]

Asixth,
I think Hokie has covered the subject like a pro as normal, but I will give my 2 cents.

Exposed concrete within 50m of the sea you want a very dense concrete matrix (I change the concrete to an S—mix depending on the run I would add extra fly ash, cement and some additives) then you want a top notch curing agent wax emulsions are my preferred product this close to the sea.


An expert is a man who has made all the mistakes which can be made in a very narrow field

 

[asixth]

thanks guys

 

[sdz]

Agree with above that curing is necessary and AS3600 4.5 requires 7 days curing for B1+ exposure; 3 days for A1 & A2.
Since builders normally want to get on asap I think a curing compound that meets AS3779 requirements would be good. Wax is good but can be slippery which may be a WHS problem.