Lime vs cement?

Cement is unforgiving and always cracks, regardless of the building"s age.

Lime is forgiving, whilst retaining flexibility once cured, but lime is also self healing in the unkikely event of any slight cracking forming.

Unfortunately far too many people didn't study sciences too well, and today we see far too much of a "lime vs cement" type thinking, along with new found "armchair experts" who've been reading other  "new found armchair experts' opinions online and / or watching too many new found DIY armchair experts creating youtube videos.

After  Lecturering  in building craft sciences once, said we'll explain a bit further:

Despite schools still pumping out three states of matter; solids, liquids and gasses, and whilst every building is a complex mix of all three of those, there is also a huge involvement with English, Maths, and Engineering.

Once we expand physics further into quantum, Particle, and Atomic Physics we find that there is actually nothing on earth that is  truly  solid becase Atoms are in a perpetual state of electro magnetic energy but because they are basically invisible to the naked eye, and even to most  microscopes, they tend to get forgotten about in day to day life.

So no building is in fact solid. (See our Building Sciences  page also for more info)

Further to this, natural humidity and temperature variations cause differential  expansion and contraction of each and every individual element used in the construction and use of every building.

So buildings do move, and on a day by day, hour by hour, minute by minute basis.

Lime is a natural earth product, and when we use it, for example as an external render mix, we mix water with the lime and the aggregate, we then apply that render mix to to a substrate where then the water content from the mix naturally evaporates out into the atmosphere, and CO² is absorbed from the atmosphere into the lime, and this is how lime products dry and harden.

If any cracks might appear, the lime just waits until it rains again. That rain gets into those slight cracks, re-evaporates again, CO² is re-absorbed again, lime is dry and hardened again.

Ordinary Portland Cement (OPC) (or "cement") sets through a chemical ptocess with the water meaning once it's set, it's set. then colder temps arrive; frosty winter mornings where the water trapped inside the set OPC freezes.

When water freezes it changes from a lieuid state of matter to a "solid" state of matter, but in doing do it expands in volume by approx 9-11%, and this is where the damage occurs,  only now it's done, there's no self healing as there is with lime because the added chemicals don't allow for that.

Now is another very important part which a huge amount of today's so called online "experts" simply do not know.

There are a vast amount of confusing names today for lime:

Hydrated lime
Quick lime
Fat lime
Lime putty
Hot lime
Hydraulic lime

Non hydraulic lime

Air lime

To name a few.

Thon main two you eally need to know are hydraulic lime and non hydraulic lime.

Hydraulic lime is similar to OPC in that it uses additives to create a set with water.

Non hydraulic lime is pure natural lime which drys and hardens by evaporation of the water and absorption of the CO²

So a non hydraulic lime render mix is the better of the two options as Non hydraulic  Lime provides very good capillarity which is vital for managing moisture transfer, and flexibility in older buildings whereas Hydraulic limes are used for limecrete / screeded floors or other subterrainean situations where the presence of ground water is constant and thereforevtyevrisk of freezingnin greater, plus Hydraulic Lime mixes also rare resistant to earth salts.

Lime is also a natural anti bacterial agent meaning less chances for bacterial, mould, and fungal growths to occur = more healthy home.

Lime is not just simply another building material, and it's most certainly not a new material. Evidence of it's use in buildings stretches as far back as 10,000 years ago!

At Heritage Lane, we understand the importance of using traditional lime products in buildings to maintain the authenticity, functionality and charm of properties and architectural features of any historic building.