Doesn't sound promising. Portland needs to be kept as dry as possible. If you can't break the lumps with your fingers it's no good. Sorry to be the bearer of bad news.

Irmgaard you mught be able to save it with a coating of good concrete on the back for strength. Use a concrete glue.
Then paint and seal it well.

Tango my white portlands suffers from this condition as well.
Screening helps but in my stuff I just consider the white dots a 'feature'.

tufaenough: Thanks for the suggestion, I'm going to try that, how do I use "concrete glue". Do I paint it on the back before I pat on good cement.
Any suggestions on how to dispose of this bag of portland, I've only used prolly 10% of it. I would feel bad just dumping it in a land fill.

Irmgaard, I'm pretty sure it's not repairable. The weakness isn't just on the surface, it's all the way through -- the entire strength of the piece has been compromised. No surface treatment in the world is going to go deep enough to strengthen it.

I would just write it off as a learning experience. It's really too bad that it was on such a large piece, with so much time and effort involved.

On the bright side: you will NEVER use concrete that isn't free-flowing again!

Tip: garbage cans don't really seal against moisture, esp the metal ones (if they still make them). A better storage container would be some of those 5-gal buckets with lids. Three of those will take one 94-lb bag of cement. I just have the guys load the bag for me, and when I get home, I cut the top (flattest) side with scissors in an H shape, then scoop it out into the buckets. Scoops made from washed bleach or vinegar bottles (gallon) are great cement and sand scoops.

Sorry about your leaf -- that's a heartbreaker.

Sue

Irmgaard as long as you can back the leaf without breaking it you should be fine. That will be the tough part but you havr nothing to lose. It won't cost much to put a layer of crete on the back.
Make sure the leaf is good and wet and coat it with Elmer's wood glue or concrete glue.
The top of your leaf sounds as hard as some peat recipes ever get so if you don't break it supporting the back a good coat of paint could allow you to enjoy the leaf for years.

Thanks Sue, I could tell you were a girl/woman before I saw your name. The men are lucky when I comes to lugging cement around. I have some of those pails but not lids, rubber maid tubs prolly arent' air tight enough either...
Tufaenough: the really strange part is that we did a couple of other projects that day, from the same cement, that are apparently doing fine, seem to be perfectly hard, and they were done from the top of the bag with the most chunks. Is it possible that differnet parts of the bag absorb mixed levels of moisture? Plus that fact that my husband was trying to help me and was really psing me off by putting what I considered to be too much water in it, It was like SOUP and thats the one that turned out the best This cement stuff doesn't seem consistant at all.
I'll let you know how the attempt to save works, I am encouraged by the fact that I was able to turn it over carfully with out breaking it using the thickest part in the middle.

Irmgaard I suspected your concrete was not completely bad from your description.
Is it possible in the heat you let the surface of the leaf dry out too quickly. That will certainly weaken the concrete and leave you with a softer surface.

I left it right on the moist sand, misted it and covered it with what used to be a water bed bladder (cut up into 1 layer/gold color not black). But it has been so bloody HOT the last 2 weeks! And it did have sun on it in the late afternoon...?

Oh, my goodness ! I had no idea ! I was given a bag of portland, and have been using it for leaves[small ones,only a couple of inches], as well as 'tufa. It had these lumps,like you described. I sifted the cement, and tossed the lumps into a bag of quickrite concrete I was going to use for fence posts,figured the lumps would act as agregate,like gravel. So far, I haven't seen any problems... But? I have used almost a whole bag, that means a lot of work. Now what?

Mudwitch, Sifting the portland was the best thing you could've done. You got rid of the portland that had moisture problems. I dont know as I'd use the lumps as aggregate though. Even though they seem hard they may not hold up in the long run and breakdown leaving voids in your concrete. I think your projects will be fine.

Personally, I wouldn't sweat using Portland lumps around a fence post as long as you were tossing it into the reqular Quikcrete (etc) concrete mix.

The only rule that I've ever heard from professionals was not to use cement that was lumpy. They didn't say sift out the lumps and use the powder. They just said not to use it. Donate it to the next post hole project and get a new bag. It's just not worth agonizing about a $6 bag of the stuff, and possibly watching the results of your labor break, crumble or otherwise fall apart. And having to explain to a paying client is even worse.

Sue

Professionals say that because time is money and they won't spend the time to sift it because it's so cheap to replace it for them. However for personal projects sifting is fine. If you're making things for paying customers, then you are a professional and Sue is correct, get a new bag.

What if you make stuff for paying customers but you're also cheap...like me.:)
And the white stuff isn't THAT cheap. Over $20 a bag with taxes.
I put all my Portlands through screens if I'm using color.
I still hate throwing away the lumps, but I do.

Rockhewer, Thank you for your information. If I had a clue that the work was to be in jeporday, I would not have used any of it, I won't in the future. The bag was given to me, so I took advantage.
Belgianpup, Thanks,you are right, not worth agonizing over, and explaining would be an agony. So far, the work I did with it seems ok, If it shows bad signs, I'll pitch it and start over. Sad to learn late, but worth learning anyway.
Rockhewer, Oh, my... a professional !! me?.. wow, I guess that's right.I've been scrambling to learn and produce, I just hadn't thought. I started this in Feb. when I lost my regular job, and thought I'd take advantage of the opportunity,I may never get another chance.The old dilema,I have time but no $ or I have $ but no time..So far I make my grocery $ at the market. I may be poor... but having a whole lot of fun. I should feel guilty, But I'm too busy.

Let's take a moment to mourn the passing of yet another bag of white portland!I just took a mask out of the mold and man!It's so badly pocked that I wouldn't bother trying to fix it.In the case of this fairly new bag,there is eveidence of crumbly little bits-I'll try screening the next time,so that I don't waste any more white cement.And,both bags were the same brand.I'll check back with you about that name;meanwhile,I'll contact the manufacturer and get some indication of what the hell is going on!
The bags,BTW,were stored in plastic garbage cans,with tight lids.The bags,from purchase,are less than six months old.Thankfully,I've got enough stock ready for our major craft show in August.Grey cement?Just fine,thank you for asking.Nice and fine,no lumps,so it's not the environment.

You can always add white pigment to grey portland to make it white.
According to an outfit that makes White gravestones, this way is cheaper than buying white portland.
Works great as long as white is the only color you try to add.:)

I believe it was Lynn Olsen who said white cement is more sensitive to environmental moisture than the regular gray.

Somewhere else, I read that white cement has a shelf life of approximately 3 months. Pretty short for the price!

Sue