Extremely heavy and therefore relatively expensive Limestone has been used throughout history for some of our most prestigious buildings and monuments . Any building that a designer wanted to specifically portray quality, integrity and magnificence (eg. savings banks, mansions, parliamentary buildings and churches, even the Great Pyramid of Giza* **) Limestone was one of the top building materials of choice.
One of the points of note that Paul came back with from the ICREC conference in Western Australia, was their wide use of rammed limestone and it’s great colour – from warm creams to bright whites.
As a bit of an experiment a sample block rammed was up in time for the Auckland Homeshow this September and was widely admired (and much handled - people were so drawn to it they couldn't help touching it's smooth white surface).
Initial testing is showing that rammed limestone is at least as strong as the rammed earth, if not stronger (testing three times stronger than the target strength required by our structural engineer). So this is looking like a great potential material for us and we think due to it's colour, will prove really popular.
And as Limestone quarries are relatively common in NZ – this will give us ready access to dry raw materials, already graded and ready to use. At this stage we’re not envisioning that rammed limestone will be any more expensive than the soils we’ve traditionally used. If white cement is used for a lighter/ whiter walls (a little more costly than Portland cement) then there will be a small cost increase which we think will add about $2-3k to the cost of the walls for an 180 m2 home.
Some of our clients will still prefer the warmth, hues and tones of traditionally used earth over limestone, but we’re just delighted that we may be able to offer this choice.
* other pyramids are made of granite
** The Great Pyramid of Giza – we were once taught was built with huge blocks of limestone, hauled up it’s sides over ramps by thousands of slaves but further research has found blocks of 70 tonnes, 40 meters up the pyramids would have been impossible to move with less than 2000 men. The wheel hadn’t been invented yet and in the time frame it was built (20yrs) this would have meant the laying of 400 blocks of day. A hard stone, the limestone would have been virtually impossible to cut (there is a carving theory – but no evidence of the detris that the manufacturing would have left behind). The most logical outcome is actually they were built in situ with rammed limestone and there is more and more information coming up on the internet to back this – a theory that Paul actually came up with when he first learnt about RE, 25yrs ago. He's always talked about this idea, so it's amazing to now see scientists backing this theory too.