The goal of life is living in agreement with it - Zeno 335BC - 264BC
Environmental
Lime is recyclable and biodegradable.
Limestone is burnt at around 900°C compared to around 1300°C for cement. This saves on fuel consumption and emissions of pollution and greenhouse gases.
Lime is less dense than cement, which saves on transport fuel.
Lime mortars allow bricks to be recycled as you can get the mortar off, unlike cement.
Cements contain heavy metals which are put into the air on burning: lime doesn’t.
Lime is an important part of any ‘natural house’ – involving timber, straw-bales, lime and earth, all of which are natural, healthy and biodegradable.
Gypsum - used to make plasters and plasterboard - is mined using strip mining techniques which devastate the ecology of the areas where the mining takes place - the top layers of earth, including all flora and fauna, are simply stripped away to reveal the deposits beneath.
Allows masonry to be re-cycled at end of life, cement does not.
Other Benefits
Lime is breathable, so any moisture that enters a structure through a crack, can escape. This isn’t the case with cement.
Lime is soft and flexible, so if a building moves slightly it won’t crack like cement, and let water in.
With cement mortars, the only way moisture can escape is through the brick, which can begin to erode away.
Natural mortars aesthetically enhance the appearance of masonry.
Breathability?
The way older dwellings are built affects the best way to repair and decorate them. Old buildings were traditionally of solid wall construction, rendered with breathable mortars and limewashed. These materials reduce the effects of condensation and allow the moisture in the walls to evaporate to the outside. Misguidedly trying to seal the weather out of traditional structures can lead to dampness, rot and condensation problems, causing decay in structural timbers and damage to the cob and stone walls themselves.
Special Properties
Being alkali, limewash is anti-bacterial thus reducing the risk of woodworm; as it's also insecticidal the death-watch beetle avoids it like the plague! It also has fireproofing qualities - King John ordered all the properties along the Thames, lime plastered and lime washed after the great fire of 1212 as a precautionary measure.