Enough Lime In The Mortar ?

[happyjune]

Well the subject kind of says it all, I have seen several walls constructed in Thailand an the mortar is very sandy but not sticky, and they tend to crack very easily.

Also they put a huge amount of mortar between the bricks, common to see as much mortar as brick.

I have been told and I think I even read on here but I can not find it in search, to add a bit of lime to the mixture and make sure the brickies don't go overboard using the mortar.

Does anyone have any suggestions?

[Soutpeel]

The vast majority of cement is lime in portland cement....therefore the problem can only be the mix proportions they are using, typically for brick mortar should be using around a 3:1 mix....ie 3 parts sand to 1 part cement, and should be putting down about 0.5" of mortar between the bricks, put too much and it will crack.

Can also throw in some washing up liquid as a plasticizer ( a lot cheaper than buying commerical product)

[JAS21]

Can also throw in some washing up liquid as a plasticizer ( a lot cheaper than buying commerical product)

You may very well get away with it in a country that does not suffer severe cold weather.....be careful to only use a little else you will get air bubbles and the bond will be weaker...in cold countries water can get entrained in the 'air bubbles' freeze and crack. But really is the saving worth the risk..............

With a proper plasticzer there is no problem with overmixing..you won't get air bubbles. I have seen jobs in the UK where the surveyor has discovered this practice and has had the wall knocked down and rebuilt!

[Soutpeel]

You may very well get away with it in a country that does not suffer severe cold weather.....be careful to only use a little else you will get air bubbles and the bond will be weaker...in cold countries water can get entrained in the 'air bubbles' freeze and crack. But really is the saving worth the risk..............

With a proper plasticzer there is no problem with overmixing..you won't get air bubbles. I have seen jobs in the UK where the surveyor has discovered this practice and has had the wall knocked down and rebuilt!

Seeing as we are talking about Thailand, think we can assume we are not going to get UK weather, so dont think there would be a big risk........but you are correct for colder climates

Think we can be pretty much assured the average Thai builder has never even heard of plasticizer in the mortar...

Edited July 27, 2011 by Soutpeel

[Gonsalviz]

Because they use sand as filler. They need to add more gravel and less sand.

[LennyW]

Because they use sand as filler. They need to add more gravel and less sand.

I dont think the OP is talking about concrete !!

[Gonsalviz]

Because they use sand as filler. They need to add more gravel and less sand.

I dont think the OP is talking about concrete !!

Ah. I read again.

[PattayaParent]

The vast majority of cement is lime in portland cement....therefore the problem can only be the mix proportions they are using, typically for brick mortar should be using around a 3:1 mix....ie 3 parts sand to 1 part cement, and should be putting down about 0.5" of mortar between the bricks, put too much and it will crack.

Can also throw in some washing up liquid as a plasticizer ( a lot cheaper than buying commerical product)

If the lemon flavoured washing up liquid was used would this also be a good additional source of lime?

Edited July 28, 2011 by PattayaParent

[Soutpeel]

The vast majority of cement is lime in portland cement....therefore the problem can only be the mix proportions they are using, typically for brick mortar should be using around a 3:1 mix....ie 3 parts sand to 1 part cement, and should be putting down about 0.5" of mortar between the bricks, put too much and it will crack.

Can also throw in some washing up liquid as a plasticizer ( a lot cheaper than buying commerical product)

If the lemon flavoured washing up liquid was used would this also be a good additional source of lime?

There we go...problem solved....lime flavoured fairy liquid....

[happyjune]

typically for brick mortar should be using around a 3:1 mix....ie 3 parts sand to 1 part cement, and should be putting down about 0.5" of mortar between the bricks, put too much and it will crack.

Southpeel, can you pls confirm you mean half an inch? That is what I see more developed countries. Maybe what I was seeing here was many more parts of sand : 1 part cement to save cost, and 4cm of mortar to save cost or they are just completely clueless, or all three..

put too much and it will crack What, you mean it's not meant o crack after 6 months? now I am really confused.

reply's .

[Soutpeel]

typically for brick mortar should be using around a 3:1 mix....ie 3 parts sand to 1 part cement, and should be putting down about 0.5" of mortar between the bricks, put too much and it will crack.

Southpeel, can you pls confirm you mean half an inch? That is what I see more developed countries. Maybe what I was seeing here was many more parts of sand : 1 part cement to save cost, and 4cm of mortar to save cost or they are just completely clueless, or all three..

put too much and it will crack What, you mean it's not meant o crack after 6 months? now I am really confused.

reply's .

Mortar mix should be 3 parts sand and 1 part cement - yes they could be using a greater proportion of sand ie 5:1 - 6:1, to who knows, the more sand the weaker structually the resultant mortar will be.

The 0.5" I am taking about is the width of the joint (mortar) between the bricks, if you put significantly more, utilmately the mortar will start breaking up/cracking/falling apart.

Based on your discription, I would think the mix ratio of sand and cement is the primary root cause, ie they are putting in too much sand to save cost on the mortar

Edited July 29, 2011 by Soutpeel