Lime Plastered vs Cement Plastered Masonry - Research Data

In this video we compare the behavior of a lime plastered wall vs a cement plastered wall. Some very interesting findings.
Another video compares an exposed brick wall vs a lime plastered wall.
• Lime Plastered vs Expo...
More technical info: www.coreconservation.co.uk/ri...

[@MinorScalesMajorFuckups]

Wow. I really love this about youtube, and internet in general. You have put so much good work into this experiment and it´s really interesting and useful. And you made a documentary that i can watch in 10 minutes. One can learn anything through youtube these days.

[@coreconservation]

Glad you enjoy it! Thank you.

[@godstonebenefice]

It is good experiment that tries to move the debate on from what people think they have observed to expreimental data. Obviously it needs to be replicated and more data obtained, but it is a excellent start. There is also a need to develop further experiments to test the impact of render on an external wall for example. Thank you for this.

[@coreconservation]

Thank you for your comment. You are absolutely right: more research is needed as lots of debate on a topic means little actual data, lots of uncertainty and opinions.

[@andrzejb941]

It would be interesting to see how all of those three walls would behave in a very light wind, as from what I found out so far, the lime plaster is supposed to make the wall dry really well, but without wind the water is not picked up from the surface as well as it could From what I found out so far I would expect that the difference would be much bigger for lime plaster than for cement one

[@coreconservation]

Lime indeed has a drying effect, but it's not water that keeps the walls damp but the hygroscopic salts. In the presence of salts the wall will not dry or dry significantly slower, with or without lime. More info here: www.coreconservation.co.uk/drying-breathability-moisture-barriers/

[@9mil168]

wow... thanks!

[@coreconservation]

You're welcome!

[@alanyoung7532]

Very interesting even if it it does not fully duplicate the complex conditions in the external wall of a building in use. It certainly demonstrates that cement rich mortar traps moisture - far more than I had suspected. Would be even more interesting if realistic mortars had been used and the perps fully filled as I understand that the changes in materials (and associated pore structure at the interfaces) at each bed joint is part of the reason moisture rise is inhibited. The mortar must be important as when I have stood old stock bricks on end in trays containing wet soil (in my shed) the moisture (and moss formation) only reached about 150mm max. Maybe this is why BRED 245 suggest samples are most often best taken from the mortar - usually more porous and uniform than the bricks. Keep up the good work.

[@coreconservation]

This experiment was part of a series of experiments we have undertaken to study the movement of moisture. It is virtually impossible to to understand and evaluate what happens in an old wall fabric if one jumps straight into it as it is a VERY complex process. We started studying how moisture moves in ONE single brick, then SEVERAL bricks separated with a simple mortar bed, then this experiment with SMALL WALLS built onto the soil, then migrating to REAL buildings. Going through this process took us about 2 years. Firstly, because each experiment lasted from a few weeks to a few months. Secondly, because we have redone some of these experiments several times to validate the findings. Thirdly, because the phenomena were really complex. But it resulted in some invaluable findings. We still carry on with other experiments and we would like to explore more in depth different materials, how they affect the movement of water and further understand the differences between lime, cement, various types bricks and stones.

[@alanyoung7532]

It is very commendable that you are investing time to investigation this important subject as this is most certainly needed.

[@jamesbusby6803]

Good experiment but you wouldn't lime plaster to the ground. There would be lime mortared brick exposed at the base. You should use reclaimed hand made bricks not tightly fired modern factory bricks. You should use lime mortar on the lime wall and cement mortar on the cement wall. NHL 2 is still too tight for a lime mix. Use either real fat lime (putty) or quick lime. Should be blended with a well washed sand. The walls should be exposed to the weather.

[@coreconservation]

Hi James, this was just an experiment. In a real world scenario we would use different lime mixes, especially if the wall is damp and salty. You use a regular lime plaster on such walls and the water and salts will break it down. Using this scratch coat will make the plastering last for decades, and yes, this lime plaster can also be used on cement walls. The Romans knew what they were doing 2000 years ago... www.coreconservation.co.uk/rinzaffo-salt-resistant-scratch-coat/

[@alanyoung7532]

I agree that these walls are not constructed as would be the case in a real building therefore the results are only indicative.

[@northlondonmasons107]

Bricks below ground need to be hard fired and be laid in nhl 3 minimum in my opinion and walls not plastered to the ground and also a rigid slate dpc used , but it still shows that cement it shit appreciate the video