Best mix for cast leafs

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  #1  
Old 09-21-12, 07:47 PM
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Best mix for cast leafs

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My wife and I have been making cast leaf imprints out of cement type products. (more on that soon) We have had some success, but on the last batch she made, many have broke from light handling, some just from picking them up.

We kind of have a mixture of different mixes due to getting them free or just picking up the wrong stuff. I/we are wondering what would be the best mix for something like this? We have used:
Type S Mason mix by Quikrete
Type N mortar mix Spec mix
Type S masonry cement
Unsanded grout (we got this free)

The castings are 1/4 - 3/4" thick and we have not put any reinforcement in them. We have ones that are outside in freezing temps and have not broken. Surprisingly we have one large one made out of straight cement that has held together. Concrete is not a good option due to the large rocks.
 
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Old 09-21-12, 10:54 PM
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Out of the 4 that you mentioned, the type N mortar is what I would choose.
 
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Old 09-22-12, 06:31 AM
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Are you mixing the mortar per instructions? While quickcrete is pre mixed, mortar generally needs to have 3 parts sand mixed in.
 
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Old 09-22-12, 07:45 AM
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That's Portland that takes the 3 parts sand, not mortar mix.
 
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Old 09-22-12, 09:30 AM
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What about the traditional plaster of Paris?
 
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Old 09-22-12, 10:25 AM
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Plaster of Paris is not durable.

Both SpecMix and Quikrete are pre-blended proportioned packaged mixes that do contain the sand. If you get ambitious, you can easily get 3000# bags of SpecMix.

Dick
 
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Old 09-22-12, 01:34 PM
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That's Portland that takes the 3 parts sand, not mortar mix.
I know the pre mixed mortar doesn't need sand added but the regular bags of N or S type mortar need sand added - it's still 3 parts sand, 1 part mortar, right?
 
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Old 09-22-12, 02:52 PM
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Yes, that would be the normal ratio.
 
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Old 09-22-12, 03:11 PM
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It all depends on whether you are making concrete or mortar.

There are several types of cement made - Portland, Masonry or Mortar. Companies like SpecMix, Sakrete, Quikrete, Handicrete and others buy the cement from a cement company.

Portland cement is the basis for all of these and the masonry and mortar cement have other materials added for convenience and properties. Most of these cements are bagged and sold by cement companies in their bags. The cement companies sell the cement to the baggers that proportion it with additives and with sand in the case of mortar mixes. Just because the name of the bag is the same, that is not a guarantee that a product with that name is actually the same as something else in a different region because they all use the local aggregates in proportions to satisfy the local demands. Mortar and masonry cements are not intended for "poring" concrete.

Traditionally, modern mortar was a mixture of Portland Cement and and lime with the proportions depending on the desired properties (workability-first criteria, strength-second criteria and others depending on the use and materials). Usually the amount of aggregate (sand) is 2-3/4 to 3-1/4 times the volume of the cementitous materials (cement and lime). The standard specifications for mortar advise that the mortar strength should be as low as possible to carry the loads since other properties may be more important.

Mortar is a unique product and there is still the age old fallacy/confusion between pouring cement and pouring/placing concrete and making mortar(or cement or concrete) by many people in the trades. Some even think that pouring a slab is "masonry", but it is not masonry and many contractors in the know advertise themselves as Concrete and Masonry Contractors because they know there is a difference and not all are really qualified to do both.

Regarding the OP, the mortar products referenced are not made for the use, but they can be used very successfully because of the local aggregates used, moisture content when placed and the curing. Something that thin is a very dicey thing to make and rely on especially if durability in the far north is desired.

Dick
 
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Old 09-22-12, 06:28 PM
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That's good info & I was thinking of the how thin his product is. I felt I picked the best out of the choices that he presented.
 
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Old 09-23-12, 08:45 AM
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Thanks to all that replied, especially ConcreteMasonry for the detailed reply. I know that we are "out of the norm" of these products, but this is just a little crafty thing my wife wanted to do and we are having fun with it. (The picture is not one we did, but are quite similar to them)

I am more than willing to go buy any other product. These were the only ones we have tried. I will look and see if I can find 3000# Specmix.

@ Mark - The Mortar and Mason mix both have sand in them. Only the cement does not have any sand. The only reason I know this is because I can see/feel it.
 
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Old 09-23-12, 11:28 AM
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Tolyn -

SpecMix is a local company for you (St. Paul) and they developed the big bag concept and licenses it nationally for others to produce.

Unless you use large volumes fairly quickly, it is not for you. Even though the sand is dried, there is always the problem with moisture being attracted and shortening the "shelf life". On top of that you need a silo or frame to hang the bag and dispense it. - Then you need a way to raise the bag and dump it (forklift). Moving a 3000# bag about 15 to 20 feet up is not easy. That is why they also make small bags.

The big bags are the most common method of using per-proportioned mortar, especially when it comes to economics and uniformity on small to large commercial masonry jobs and especially on contolled quality jobs.

Dick
 
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Old 09-23-12, 12:09 PM
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LOL! I thought the 3000# was the PSI of the mix, similar to 5000# concrete. Shows what a noob I am about this. However, we went to Big orange and I knew more than the guys there so I feel a little better.
 
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