WHAT IS THE DIFFERENCE BETWEEN CEMENT & MORTAR MIX?

Mmathis

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Portland cement, mortar mix, mortar cement..... For making faux rocks, some recipes call for mortar mix, and/or cement (plus sand & other various ingredients). Talking about cement and not concrete mix.

The guy at HOME DEPOT told me that mortar mix was just P. cement with sand added (of course, he also informed me that all water turtles were amphibians). Then, I saw a product on the shelf at LOWES called "mortar cement.". The guy there told me it was mortar mix with cement added.

So, what are the applications for these and to what degree are they interchangeable (for faux rocks, that is)?
 

sissy

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some have aggregate in it meaning lots of small stones .I use motor mix as it has a smooth consistency and non of those little rocks .I also add fiberglass fibers you can buy in a bag ,makes the faux rock stronger .They use mortar to do basement concrete block walls .Then there is floor tile mortar and even grout works if you seal it .Now you can buy also counter top mortar in colors to make sinks also ,but expensive .
 

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David V
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concrete = cement + aggregates

adding fiber is always good, keeps you regular; oops, I mean adding fiber to cement
 

sissy

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oh dear lmao .You might need an out house if you add to much fiber.My out house shed even a man with a stick to beat people off
 

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David V
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I forgot to mention this, but Sissy is correct to add fiber to cement or concrete, whatever the case may be. Normally in construction, roads, sidewalks, etc, concrete is reinforced with rebar. However, when working on small projects this can present problems, namely rust expansion. Unless the rebar is buried 4 inches away from the surface, rust will expand and thereby cause catastrophic cracking. You could get around this by using galvanized steel but even some galvanizing, especially coming from China, can wear away and rust

Dave, just a regular guy
 

Mmathis

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Glad everyone is regular today :)

But mainly, how is mortar mix different from Portland cement? Can they be used interchangeably for making rocks? I have a bag of P.cement that I've been mixing with mortar mix and sand (not sure where I got that recipe...). Do I even need to be mixing the 2 or can I use one in place of the other??

And where can I get the fiber (fiberglass)? Do places like HOME DEPOT carry it? How does it come: bag, box, by the pound, etc?

Guess I'll just eat an apple for now :)
 

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mortar is basically cement, sand and proprietary stuff thrown in such as epoxy or resin, maybe or maybe not, to give it flexibility if stuff starts shifting such as earthquakes. I believe in addition to the factor of rusting, the fibers also give some elasticity.

I generally make up my own mixes, depending on what I need. The strongest is concrete (sand, portland, aggregates). Mortar is the weakest and I use it when I want to carve something in it later or buff it down. Generally, I make my own mixtures of portland, mortar and crusher fines (aka, slurry, quarter minus, breeze and so on)
 

sissy

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usually in a bag and not all stores carry it .The home depot and lowes in Danville and Martinsville don't carry it and i go to NC and get it.I have never had any problem with mortar if i use a sealer .I even had left over sealer for my grouting I did on my glass back splash and it worked .I usually use the milky kind of sealer for wood .cleans up with water and i get the non glossy type .I even made one rock out of grout mixed with the fibers and it has held up pretty good .I even made one of the hypetufa ones because I made flower pots and had some left
 
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Here's one recipe I use to make rocks. good for starting out I think.
finished.jpg


But mainly, how is mortar mix different from Portland cement?
Portland cement is the main ingredient in all other cement type products like concrete, mortar, stucco, tile thin set, grout. Think of it as four in baking. Cake and most cookies are mostly flour. By adding a few other things in different amounts you get different bake goods.

Mortar is a general term that can mean anything from clay based to very high tech materials. When a package says something like "mortar cement" they're telling you it isn't mud mortar, it isn't lime mortar, instead they're saying this mortar is made with Portland cement. Cement mortars generally also have lime as an ingredient to make them more flexible.

As others have said, the difference between concrete and mortar is the size of the rock added. Mortar uses sand and smaller rock down to dust size. Concrete uses some sand, but also pea size and larger rock. Rock is stronger than cement so using larger rock (of the right kind) yields a stronger result. There are many recipes for concrete, just like there are for mortar. We use the terms mortar and concrete as a way to differentiate between the two basic differences in recipes and uses. It's like saying cake vs cookie. We all understand the difference between a cake and a cookie. A cookie (most) can be put into a baggie and placed in a lunch bag, but a piece of cake won't hold up.

Most premixed mortars will say Type M, Type S, Type N, Type O to describe the ingredient recipe. Each type is used for a specific application. For example, Type M has the highest percentage of Portland cement and is the strongest. Everyone new to working with cement products always want the strongest, right? Why would there be any other kinds? There's a down side, the more Portland the more shrinkage, the more cracking. Especially a problem when making rocks if you're forming the entire rock from mortar. Less of a problem if the mortar is a final coat over a cured base.

For making rocks you generally want a softer product. I like Type S for most cases. If the rocks are to be walked on I'll use a Type M and deal with the cracking by making a substructure first. For the easiest to work and best detail I use Type S and add a product called "mortar clay", but it doesn't wear great. When walked on it will wear fast, although that's a nice look too.

I have a bag of P.cement that I've been mixing with mortar mix and sand (not sure where I got that recipe...). Do I even need to be mixing the 2 or can I use one in place of the other??
Adding more Portland to premixed mortar is generally a bad idea unless you know what your doing. Result is harder, but more brittle, and more prone to cracking when curing.

And where can I get the fiber (fiberglass)? Do places like HOME DEPOT carry it? How does it come: bag, box, by the pound, etc?
Fiber is generally a really bad idea when making rocks as you will soon find out. The little bits of fiber will poke out and be visible. You can use them in building a base structure. For example, start with some mesh or chicken wire and spread a little mortar with fiber over the wire and let that cure. Now you can apply a layer of mortar without fiber over that and form the final rock surface. But fiber use is normally far, far from being needed.

The same is true for using concrete to make rocks. Concrete is stronger and wears better than mortar, but the large rock chunks making forming and smoothing just about impossible to make good looking rocks.

People new to working with cement products are obsessed with strength...but that's inexperience. Glass is very strong, but makes a poor baseball bat. Rubber is very soft and flexible but also make a poor bat, though you'd never break a rubber bat. Wood was the best material for bats for a long time, just enough strength, but also flexible enough to not break too often. Now they have even more high tech bats. Stronger can mean softer and more flexible.

Resist the typical novice approach thinking you can improve on thousands of years of material use and process with no experience. Instead start with standard practices and learn. Then, after you know something, you can change recipes and methods if you like.

Never ask a person working at a store anything about their products. Generally they don't even know where products are located in the store, much less how they're used. They will just BS you and no info is better than BS info.
 

sissy

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I save a slurry of cement to put over my faux rock if any fibers show and i do use chicken wire to make the forms or add it in to make the hollow rock more break or crack resistent and so far has worked .It comes down to whatever you find easier to use and sure you want it to last but you never really know what will last .I have found it easy to try different things as concrete is not really that expensive and you never know you may come up with a mix that works better .I know they now sell a lot of additives now that people are using concrete for counter tops and sinks .I love the white counter top cement it gets really hard and is really smooth if you vibrate it to get air bubbles out .But downfall not cheap .
 
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Let me add this, from my experience of having a mason for a father; mortar is designed to be weaker than the bricks to which it adheres, and is more gray in color. jCement is stronger, whiter, and waterproof (my dad used to coat his 'cement' aquariums with pure cement powder to guarantee it wouldn't seep/leak. If you get the parts separately (as my dad used to do), sharp sand is what you want for better strength re doing brickwork. Play sand or that type, is too rounded and considered soft, and isn't good to use. Re making rocks, well, if you want them to be harder, best to use cement based. I'd never use mortar for anything but joining brick as it's just not designed to be that strong. And concrete would be your stronger mix, if you could keep the stones from lying too near your exposed surfaces. Most concrete is 'floated', to get the cement 'cream' to rise to the top, forcing the stone down near the base where it makes for a stronger slab.

So for example; for my house, I laid it all with mortar between the brick. For the paver walkway, I used cement because it makes a more durable base (and I used it as my grout between pavers as well for the same reason; that was in '87 and I haven't lost a brick yet nor has it cracked where I didn't expect it to) and concrete was for the garage floor and driveway because it had the best compression strength.


IF you're going to use portland cement, the 6-bag mix is stronger than what is typicaly used in either concrete or cement walkways. For your purposes, this means if you want stronger rocks and can get a bag of pure portland cement, add the latter to any pre-mix you buy (typically, it's a 2-1 ratio; cement to sand ((sharp)) that is desired) and your rocks will be harder.

Another way to get more 'backbone' in your rocks would be to embed a plastic lattice (could use metal but plastic would remove any rust issues) near the base. There has been better success with major roadway repairs when shredded fiberglas was used instead of the rebar, which is what the plastic lattice would be mimicking.

just my experience.

Michael
 

sissy

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going to have to try tis because I want to make a bigger rock and was concerned that with moving it may crack .
 
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I laid it all with mortar between the brick. For the paver walkway, I used cement because it makes a more durable base
Mortar is a generic term. Are you saying you used lime mortar to lay the brick? That is what was used 100 years ago and many masons still think it superior to cement mortar.

You used just Portland cement for the payers? Never heard of a mason doing that.
 

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I think I recall someone burning off the fibers with propane torch, but can't remember. If this were to be done, the torch would have to be moved around, perhaps circular motion, b/c loitering too long in one spot will cause flaking and even cracking (ask me how I know).

working with cement, mortar, concrete, is fun (at least to me). I'm no expert, just try different techniques & see what works, roll up sleeves. Hardest thing is hauling around 80 or 90 lb bags of Portland. Fortunately, I've been doing deadlifts once a week in my weight training. Otherwise, a pull around wagon would work.

I was amazed at how expensive faux rocks are at Lowes. Also they are so uniform in color (grey). Don't forget when experimenting with rocks to experiment with concrete dyes (liquid or powder) to get some cool looking rocks; maybe a test sample first. If you screw it up, you always can paint on some dye later as the stuff is porous and will soak it up in no time

And rock casting is another interesting topic...

Waterbug; nice tutorial, btw

DaveV
 

sissy

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I just use universal paint dyes and the sets are cheap at paint store .I found you can't find them at lowes or home depot
 

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