The Romans loved lime, and they would have loved Hempcrete too.

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The Romans were masters of construction and one of their secrets was their use of lime in building materials. As you might assume, the binder is what binds it all together! Yes, but what's in it?! The binder consists of either hydrated lime or hydraulic lime, or what's more commonly referred to as Roman Cement.

If you allow us to get a bit nerdy for a minute, we make lime by kiln-firing pure limestone. The firing process removes the carbon molecules from the calcium and converts it into a fine dry powder. This is an essential component in hemp lime mixtures used in sustainable building.

When you use lime as a binder or mortar, it absorbs carbon dioxide or air and turns back into limestone. This is the meaning behind people talking about the carbon cycle - carbon and calcium truly desire to be reunited! In fact, that's why the lime starts setting as soon as you open the bag!

Now, lets go one step further. The Romans and their famous Roman cement was also kiln-fired. The difference being Roman cement has added or existing impurities known as pozzolans.

So, why Add Impurities and Why Give Them Such an Exotic Name?

Pozzolans are anything from volcanic ash, brick dust, cement, or in the case of our hempcrete blocks; a probiotic fluid (more on that later).

And the name? Two thousand five hundred years ago, the Romans quarried up volcanic ash to add into their lime mixes in a place known as Pozzuoli, next to Naples, under the watchful gaze of Vesuvius.

But why on earth did the Romans start mixing volcanic ash in their lime binder mixes???

What they found was that with this addition, their mortars would set stronger, faster and also whilst underwater. The addition of pozzolans caused lime to set in the presence of CO2 and also water.

Pozzolans allow a quicker and stronger set. The set can also occur deeper within hemp walls, whilst a pure lime may not have sufficient CO2 to set rapidly.

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One tremendously interesting fact is that hemp hurd has a high silica content. And silica just so happens to also be a pozzolan...

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So the actual hemp itself serves not only as an insulative aggregate, but to increase the strength and set speed of the lime.

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One interesting fact about RespiraBlocks is that our pozzolan is a probiotic fluid. The additive speeds up the lime carbonation process without the addition of cements as pozzolans like many competing hempcrete products.

There are many benefits of using lime blends as opposed to modern concrete Lime binders have far more plasticity and vapor permeability than modern cements, allowing moisture to pass through structures without causing the destructive ponding processes you see in modern construction.

That's right, water creates valleys, destroys concrete and will eventually erode the pyramids, so do anything you possibly can to avoid it sitting, pooling, or hanging around otherwise it will eventually destroy your home.

One only needs to look at the Colosseum or Pantheon to see the benefits of a natural lime. This reason is one of many that natural builders are so passionate and vocal about their methods. They’re time honoured, tremendously reliable, have a fraction of the carbon footprint, and the buildings they build stand long through the ages. Building with hemp and lime binders significantly enhances the sustainability of construction projects .

Thank you so much for taking the time to read our case study. We spend a great deal of time writing about hempcrete. That’s because our purpose at RespiraBuilt is to help as many people as possible to insulate our homes with a naturally grown, carbon-sequestering carbon-based lifeform which not only provides the best thermal comfort but also has a genuine positive impact on the environment, and your bank account!

We encourage you to delve into our website and educate yourself further at www.respirabuilt.com.au or to simply get in contact and pick our brains!

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