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Mortar and Grout... What is the Difference?

10/10/2010 12:11 PM

Can mortar be used to set flat stones or large tiles on a Hardiboard or backer board without the grout?

Is grout just used for looks and filling cracks or does it actually support the tiles or stones?

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#1

Re: MORTAR and GROUT..What is the Difference

10/10/2010 5:20 PM

You want to use thin set mortar to set your stone or tile. I've always used grout for the spaces after thinset has dried.

I think without the grout, you run the risk of breaking off corners of tile while walking on them.

I don't know if you could use grout or not for setting the tile. I do know it would be more expensive than using thinset.

If you google, tile installation, there are lots of good sites that will take you step by step through the process.

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#2

Re: MORTAR and GROUT..What is the Difference

10/10/2010 6:56 PM

What I was wandering is if I could just color the mortar with one of the pigments offered , mush the tiles into it so there would be NO spaces inbetween the tiles .....and then wipe the excess off as you would if you used grout .

Basically skipping the grout thing all together and just using excessive mortar to set and fill the spaces in-between.

I am not after a really pretty look , just somethingt kind of rough and rustic.

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#4
In reply to #2

Re: MORTAR and GROUT..What is the Difference

10/10/2010 11:11 PM

The thinset tile adhesive (mortar) holds the tile in place and is quite strong. Grout on the other hand has very little strength and adhesive qualities. You could use the thinset to fill in the spaces between the tiles and that would not be a problem, it's just messier to do because it does ot wipe off as easily as grout when it is dry. On a perfectly level surface you can put the tiles close together as they do with a marble floor but you have to have some method of keeping them all exactly level with one another. The small space between the tiles and the slightly rounded edges of tiles make them easier lay. You'll have to also consider the aesthetic qualities of a tile floor with no grout if you lay them touching edge to edge. You'll have to be very exact in your layout.

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#10
In reply to #2

Re: MORTAR and GROUT..What is the Difference

10/11/2010 3:47 AM

How would you get your nice neat spacing between the tiles?

The stepped process of fixing tiles and grouting, to achieve an aesthetically pleasing result, is a tried and test process. Why do you want to re-invent the process?

Go ahead and try fixing your tiles in the way your thinking. I hope your happy with the results. At the end of day as long as your happy with the results, that's all that counts. Until you come to sell your property.

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#3

Re: Mortar and Grout... What is the Difference?

10/10/2010 11:09 PM

http://www.mmgrouting.com/grout.htm

-----------------------------------------------------

Source: MASONRY CONSTRUCTION MAGAZINE

Publication date: November 1, 1995

What is the difference between grout and mortar? Can mortar or concrete be used for grout?The main difference between mortar and grout is the amount of water in the mix. Grout must be made with enough water to make it pourable or pumpable but not with so much water that the grout components segregate. Grout slump generally should be between 10 1/2 and 11 inches. Mortar, on the other hand, should contain only enough water to produce a smooth, plastic, "buttery" consistency that sticks to the trowel and is easy to spread. Mortar and grout also contain different ingredients. Mortar often contains hydrated lime; grout usually contains little if any hydrated lime (ASTM C 476, Specification for Grout for Masonry, allows up to 1/10 part lime to 1 part cement). In addition, coarse grout contains larger aggregates than mortar or fine grout. Mortar should not be substituted for grout unless the substitution is allowed by the architectural specifications. Mortar often is too stiff to flow around steel into small cavities or cores without leaving voids. These voids not only reduce strength but also can lead to water leakage problems. Mortar often is used to slush collar joints instead of filling collar joints with grout. This practice is convenient for masons but has disadvantages. First, slushing joints with mortar provides much lower strengths. ACI 530/ASCE 5/TMS 402 Building Code Requirements for Masonry Structures requires that allowable stresses be reduced by 50% when mortar is used instead of grout in collar joints. Second, the resulting voids often create channels that can carry rainwater from the outer wythe to the inner wythe. Concrete shouldn't be substituted for grout either. The coarse aggregate in concrete generally is too large for most masonry grout cavities. Also, in cast-in-place concrete, low water-cement ratios are important for strength. For this reason, water-reducing admixtures often are added to concrete instead of more water to increase flow. This isn't necessary nor desirable with grout for masonry. Because the water in grout is absorbed by brick or concrete block, the water-cement ratio of grout is greatly reduced as soon as the grout is poured into the wall. After grout that is made with a low water-cement ratio is poured into the masonry, it may not have enough water left for proper hydration and strength gain. Most problems with grout are related to too little water rather than too much water.

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#5
In reply to #3

Re: Mortar and Grout... What is the Difference?

10/10/2010 11:30 PM

Well documented--There is no substitute for facts...

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#6
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Re: Mortar and Grout... What is the Difference?

10/10/2010 11:52 PM

Cement and grout vary with water content, up to a limit. These materials set by hydrating - absorbing water and forming a hydrate network that completely fills the space = zero voids/settling.

With too much water, there is a risk that there will be free water = voids = settling? or other problems affecting the strength of the support of the machine resting on the grouted plane. If the watery grout fills a crevice against leakage, there is potential for seal failure. Grouts and cements are formulated for a certain range of water. detailed instructions are given by groutmakers for the field users to follow

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#7
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Re: Mortar and Grout... What is the Difference?

10/11/2010 12:20 AM

The problem here is that this is the wrong kind of grout, OP is interested in tile grout, similar to that used in bathroom floors and walls. The article is about filling the voids in reinforced masonry, it is the same mix that is used under some column base plates.

My advice would be to not omit tile grout, it has a sealing effect that thinset doesn't.

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#8
In reply to #7

Re: Mortar and Grout... What is the Difference?

10/11/2010 12:24 AM

yes, but tile grout must fill 100% of the space or the tile rocks, and cracks. The requirements are quite similar

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#18
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Re: Mortar and Grout... What is the Difference?

10/11/2010 11:45 AM

Masonry Grout is different than tile grout. Masonry Grout is a structural filler for things like CMU block and typically has aggregate in it. There is not aggregate in tile grout. Grout and Mortar are not used consistently through the construction industry, but rather the meaning of the terms are application dependent.

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#19
In reply to #18

Re: Mortar and Grout... What is the Difference?

10/11/2010 8:59 PM

RE:- Masonry Grout is different than tile grout. Masonry Grout is a structural filler for things like CMU block and typically has aggregate in it. There is not aggregate in tile grout. Grout and Mortar are not used consistently through the construction industry, but rather the meaning of the terms are application dependent..

I have never seen a grout with aggregate in it. In my opinion any hard lumps like that would defeat the purpose of the grout.

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#22
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Re: Mortar and Grout... What is the Difference?

10/12/2010 11:32 AM

CMU grout will typically have 3/8 inch rock sometimes 3/4 inch rock, after all it is structural and the rock is where the strength comes from. the purpose of the grout in CMU block walls is a structural filler. It fills the voids in the block and develops the structural strength, also ties the steel to the structure. Check ASTM C476 for a description of grout and you will see the aggregate added.

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#24
In reply to #3

Re: Mortar and Grout... What is the Difference?

10/17/2010 11:37 PM

Markar,

Your comments are correct for the topic of grout filling of voids in block walls and similar types of construction. However, they appear off-topic for the thread's question of grouting between tiles set on a cement board backer with thin-set mortar. Because they are well presented and informative, I am not voting against your post, however.

--JMM

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#9

Re: Mortar and Grout... What is the Difference?

10/11/2010 3:11 AM

As far as strength goes, as long as the base of the tile is fully set onto the mortar it should be fine. As you are butting all the tiles up close then the corners should be fine also.

A word of warning though, if you butt all the tiles up together you will inevitably run into problems after the third or fourth row. The tiles will probably be very slightly different in size or squareness and you will end up with some sort of run out.

I am only speaking from experience as I layed marble tiles in the same manner onto a concrete floor and it now bugs the hell out of me every day I walk over it. Now I know why you are supposed to leave a gap and grout it.

Steve

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#11

Re: Mortar and Grout... What is the Difference?

10/11/2010 8:38 AM

Lets get back on track here for a moment, please.

I am laying a small section of large 12x12 rough surface floor tiles in our bathroom.

The wife wants a tile floor just around the tub.

My first attempt had mortar oozing up through the cracks already. Now we have some cracks with gray mortar and some with the darker colored grout.

My house is old and looks are not important.

I do not want to break up what I have in place already trying to get a pretty look.

I still need to lay another small section.

The total is maybe 2 sections of 50 sq/ ft max.

IF I set this next section with too much mortar as I did on complete accident the first time, will the mortar hold these floor tiles in place and seal the floor tiles.?

Thank you all. Please remember I am not looking for anything pretty, just functional.

Besides the walls are pine planks and most of our ceiling is actually corrogated sheet tin...don't laugh...it looks good......and it hides the water stains from all the roof leaks when the big storms tear up the roof shingles.

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#12
In reply to #11

Re: Mortar and Grout... What is the Difference?

10/11/2010 9:03 AM
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#13
In reply to #11

Re: Mortar and Grout... What is the Difference?

10/11/2010 9:21 AM

Yes, you can.

Fill any hairline or small cracks with unsanded grout for a fun/funky/functional floor

from one who knows

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#14

Re: Mortar and Grout... What is the Difference?

10/11/2010 10:12 AM

OK. Last questions;

  1. The mortar can be used to set and 'fill in' the spaces.....and there will be spaces as I am using those plastic crosses to set in-between the tiles.
  2. Grout has a more water proofing effect than mortar mix?
  3. If I use a sealer over the whole thing will I get the same water proofing effect?

Thank you all again.

Net making is soooooo much easier than this home fixing thing, but I promised one extra day a week for this and that is that.

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#15
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Re: Mortar and Grout... What is the Difference?

10/11/2010 10:58 AM

Grout doesn't really have much waterproofing in itself. If you go over the grout lines with the liquid silicone waterproofing that will do it. Use two applications. Not sure about waterproofing qualities of the mortar but most concrete products are not really waterproof. You don't need to go over the whole floor with the silicone waterproofing, the ceramic tiles are waterproof, just do the lines and avoid the tile faces as much as possible as the silicone tends to make them slippery if too much gets on.

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#16
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Re: Mortar and Grout... What is the Difference?

10/11/2010 11:05 AM

Thank you Rick. That answers two questions right up front.

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#17

Re: Mortar and Grout... What is the Difference?

10/11/2010 11:13 AM

the best quality of the grout is lack of shrinkage on drying,

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#20

Re: Mortar and Grout... What is the Difference?

10/12/2010 7:22 AM

Generally as a modern term, it is associated with bathroom tiling etc, however in classic building technology grout is a thin pourable cement, this being used to fill interstices and level surfaces in stone work.

When doing gauged arches and other fine brick or stonework, they would shape the bricks into very fine tolerance shapes and use slaked lime as the grout medium, this creates beautiful thin joints.

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#21

Big difference: Proper grouting.

10/12/2010 10:03 AM

Grout serves the purpose of keeping the tiles locked in place and allowing for a feature strip due to individual tile size variances.

Grout joints can be dictated by the quality of the tile and the size.

Grout is a polymer enhance cementitious compund with latex and sand as it binding body. The latex will indicate it is not waterproof and must be sealed, however it has minimal bonding power due the water introduce while cleaning the grout upon application, too much water can cause efflorescence.

The proper process with goruting is: let the grout sit for enough time to see the haze start to form, do not spread too much at once, do not mix too much at once. Once th haze forms due the first wipe forming your grout joints with the sponge and taking the majority of the grout off the tile surface, let this haze slightly while you change your bucket of water then start your second wipe, rinse your sponge well and start at the left side of the tile, pull towards you and wipe 1 and 1/2 tiles, about 18", then flip your sponge and move over the width of the sponge, rinse repeat these steps until you have removed the majority of the grout, if you have a good sponge and are careful a third wipe can be a voided, normally this is not the case, change your water often as dirty grout-water can cause a haze and disallow proper cleaning resulting in a required acid wash.

Finally after the final haze has formed, take a towel and lightly buff the haze off being careful not to damage your new grout lines. The grout should slighty dip less than 1 to .05 mm between the tiles.

Thinset on the other hand is stronger bonding cement/sand based it is can also me enhanced with polymers and latex unless you use a nonmodified or non fortified thinset, this is ill advised based on my 28 years in the flooring industry.

While you can use thinset as grout you cannot use grout as thinset.In many third world countries the grout is the thinset.

If grout is used as a thinset it becomes what we in the industry call "water bond" this means it has no bond and the only thing keeping the tile in place is the form.

Many types of tile are not impervious as it was suggested above and will require a sealer. If the tile has low coefficiency rating it is subject to moisture permeation.

IE: Natural Stone; Marble, Granite,Limestone,Travertine,Slate etc have a low CER and must be sealed, they are all very porous. Some of these must be sealed prior to grouting or the grout will stain the surface. I have seen red juice stain honed unsealed marble.

On the other hand porcelian tiles are higher and not subject to permeation on this scale, they will however draw moisture based on the wearlayer or surface consistancy.

I have seen unglazed low CER porcelian tile draw color into from the grout. It can be cleaned but requires a sulphamic acid wash to remove it.You cannot use this style of cleaning on marbleor travertine, it will pit the surface, a strong vinegar will pit the surface.

Clay body tiles are another style, it will all depend on the wearlayer as to what CER they will be given, as you know clay is very pourous.

It is a good idea to seal all tile and grout to avoid issues with your floors, a cheap sealer will be just that, a good sealer will do the job.

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#23
In reply to #21

Re: Big difference: Proper grouting.

10/12/2010 8:40 PM

Thank you for taking the time to explain all of this. I will NEVER be a tile layer.....too much guessing at things. I like the rock solid geometry of the net business. Number don't lie........my eyes do!

Thank you.

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