How long does it take for mortar mix to harden really hard?

[DJW]

I am going to do some tuck-pointing on a square cut stone house. I am testing mixes in order to try to closely match the mortar. I have found that the newly mixed mortar does not seem to be near as hard as the original mortar even after 24 to 48 hours. Will it harden more as time goes on? I know as it hardens it should stay wet but how does this affect its hardness. Should I spay it with water a number of times a day and for how many days?

When mixing how does the amount of water affect its hardness. I laid a mud bed once for a shower stall and used a dry mix like wet beach sand and it hardened nicely. When doing a slab once I used a wetter mix and floated it a lot to get the cream up and have a smooth surface with not much aggregate showing. When it comes to mortar how wet or dry should it be?

I am trying a one to two and one to three mixes of bagged mortar to sand. The mortar I have is just straight with no sand in it already. It just that the old mortar pieces that fell out I can=92t even snap in two but with my new test mixes after 24 to 48 hours I can snap in two and also mash to a grit between my fingers. I tried a straight mortar no sand just to see if it hardened ok and it did but can still be broken with not too much effort.

[Joseph Meehan]

I don't know how hard you really want it. Frankly you don't want it too hard. The really hard stuff damages the brick during freeze thaw cycles. It will likely get harder over time. That time may be years.

[gfretwell]

The design spec on most portland cement based products is at 28 days.

[DJW]

So are you saying that it gets somewhat hard a at first but then for the next 28 days gets harder reaching maximum hardness at 28 days? Would it be a good idea to get it wet by spraying it at least once a day for the first 14 days or the full 28 or does that not matter at all?

[ransley]

Limestone? Ive just used mortar mix with good results and no damage to the stone, but if you dont like the grey color you need a custom mix.

[gfretwell]

Yes and yes. The longer it cures (wet) the stronger it gets. The hardest concrete you will ever see is what you set in a fence post hole if the soil stays moist. You get about 80% in 7 days as I recall. I have a beam that is about

10 days old and still supported. The inspector recomended 28 days on this too.

[buffalobill]

buffalo ny: don't use old bags from a damp basement. your temp and humidity are factors as well as the absorbancy of the surface, there are many brands and mixes, check specs and instructions at mfg websites. example, see:

[EXT]

Don't go by the color just after you use it as it will be light grey to whitish from the cement in the mix, after a year or two or three, the cement on the surface will wear away showing the color of the sand used in the mix. Sands can run from grey to brown or reddish color all the way to black sand. Most age to a brownish dark grey.

It works the same way road asphalt. When it is first laid down it is jet black, but a couple of years of weather will wear away the surface tar exposing the aggregate used in the mix, limestone will leave a light grey color, granite will leave a red, green, brown or black finish to the pavement. Sometimes patches are made from different supplier and create a variety of colored sections.

[DJW]

I forgot to mention it is type N mortar what is the difference between type N and M? How many types are there? Did I get the correct type? And I read that after I add the sand it becomes type S?

[ransley]

Color change wont be great, grey will be grey, with Limestone ive used White Portland and tints to not have any Grey. Grey and Limestone dont look right.

[Philip jones Jones]

replying to gfretwell, Philip jones Jones wrote: Thats is wrong. Concrete does not need other source to get strong. It will take

50 years to reach its true strength. Water has nothing to with strength infact water is more destructive than a strength maker.

[Ed Pawlowski]

If you want it to get hard fast, there is a Viagra additive to mix in. It will stay hard for more than 4 hours too.