Saturated Surface Dry & Slurry Coating

[MacGruber22]

1. Has anyone found (or implemented) a good definition of SSD that a contractor can clearly understand and follow? I tire of the laziness of contractors implementing their version of SSD, which is never even close.

2. Do you specify a cementitious slurry to be scrubbed into the ex. to remain concrete surface for typical Portland cement concrete repair mortars?



"It is imperative Cunth doesn't get his hands on those codes."

 

[Guastavino]

1. Haven't ever had to explain, but if I did, I would say, "if you were only blind you'd think it was dry, meanwhile if you could see but couldn't feel anything you'd think it was wet"

2. I haven't had to do that in a while, but the company I used to work for that did a lot of concrete repair work required that.

 

[MacGruber22]

Thanks

I will have to fashion your answer to #1 into something I can place in general notes!



"It is imperative Cunth doesn't get his hands on those codes."

 

[TehMightyEngineer]

Similar to njlutzew; I'd say "did you soak it? If yes, then does it feel dry now but not appear dry yet? That's SSD."

You might go a long way explaining the intent of SSD so they know at least what the goal is.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[BUGGAR]

There was once something about timing how long a drop of water would last before being absorbed (performed in the shade).

I like the "Contractor shall close both eyes while touching concrete surface and report findings. This shall be followed by contractor opening both eyes while observing but not touching the same concrete surface and report on these findings. etc."

 

[MacGruber22]

Ha! That may not encourage their best effort.

"It is imperative Cunth doesn't get his hands on those codes."

 

[Ron]

1. SSD is a transient property and not intended for anything other than a design parameter. You cannot likely achieve SSD in the field...it is difficult to do so in the lab and it only lasts a few minutes. It is used as a design parameter and then gets adjusted from this amount by the accommodation of higher or lower moisture contents. The moisture content at SSD can be determined in the lab for a particular aggregate.

2. Yes. This is known as a neat cement paste and is good for achieving bond between existing and new concrete.

 

[MacGruber22]

1. Well that is interesting
2. Very good

"It is imperative Cunth doesn't get his hands on those codes."

 

[Ron]

MacGruber22....The absorption of aggregate is its moisture content at the SSD condition. So if your aggregate has an absorption of 2 percent and the actual moisture content is 5 percent, the aggregate is wet of SSD by 3 percent. There are essentially 4 states that aggregates can be in.....

1. Oven dry (does not occur in the field)
2. Air dry (moisture partially fills voids in aggregate, but not saturated....occurs in field)
3. SSD (voids in aggregate are filled with water, but surface is dry....transient state, does not hold in field)
4. Wet (saturated voids plus latent water on surface of the aggregate (occurs in field)

 

[MacGruber22]

Thanks, Ron. I guess I was ignorant in thinking that there was some sort of "best effort" approach the contractor could take to get near SSD. But, it seems that it is not practical and maybe even unfair to instruct the contractor to provide SSD.

I try to specify the slurry scrub coating. However, all the times I have made site inspections, not once did I see the guys performing it. It is particularly concerning when it dry as a bone outside, but they do not seem to understand the importance of it. Though, many times it is not practical to provide the slurry coating - forming as pouring into a birdsmouth being one of them for sure.

"It is imperative Cunth doesn't get his hands on those codes."

 

[TehMightyEngineer]

If it's not practical to provide a slurry coating you can use a number of "primers" (such as Sika Armatec 110 EpoCem, one I've used in the past) that replace the slurry coating and are viable for up to 24 hours.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[MacGruber22]

teh - I have my doubts about those products. Is there independent testing to confirm their performance?

"It is imperative Cunth doesn't get his hands on those codes."

 

[TehMightyEngineer]

Not that I'm aware of and I also have doubts. I've used it in applications where I didn't suspect they were going to apply a scrub coat like they should and this allowed me to visually inspect the site and see if they did apply the bonding agent (it's a notably different color than fresh concrete). Plus the supposed corrosion inhibition was beneficial for the project I was on.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[Ron]

MacGruber22....Yes, Sika products are tested and usually perform quite well if you follow their instructions; however, a neat cement paste works well and only requires a little more labor. The materials are cheap.

 

[MacGruber22]

Thanks, teh and Ron.

"It is imperative Cunth doesn't get his hands on those codes."