The Ecomerchant Lime Range – Using lime in construction is not as confusing or difficult as you may think
At Ecomerchant we are always looking for ways to make life easier while at the same time minimising the impact on our environment. How we have developed our range of lime products is a good example.
We found that we were regularly asked for help and guidance on choosing what to use for some of the most typical and straightforward applications simply because customers found all the terminology and possible variations confusing; in many instances they were faced with mixing components in various ratios to end up with a useable products, the end result is that many of our customers found the use of lime in building confusing this meant that use was restricted to conservation and heritage applications and use elsewhere was largely the preserve of highly skilled specialists.
We realised that almost all areas where lime products can be used, plasters, mortars and renders can be achieved with just a handful of well-designed quality products and applied with established construction skills. Good plasterers can apply lime as well as gypsum and the same applies to rendering, brick laying, repairs and so on, the secret was to create consistent quality products where the only thing you need to add is water.
This is exactly how we and our suppliers arrived at our range of products. We worked together to offer technical performance products that are simple to understand and easy to use. They all benefit from the reduced levels of embodied energy and lighter environmental impact over cementitious or gypsum products, but importantly, they also match the performance and eco requirements now being established through modern methods of construction. They are breathable, long lasting, low polluting, easy to use and attractive products.
We have selected all of the most common applications and provide, sometimes a single product, to meet that demand. We are proud to describe them as easy to use, general purpose, versatile, and straightforward because we know they are the result of a great deal of technical research and refinement. With this comes a guarantee of consistency uncommon with previous self-mix application except with very experienced blenders and applicators.
We have also made our descriptions fit the product, simple clear precise and easy to understand so you should always be able to find the product you need for the job you have, and even better you can buy online or over the phone for delivery direct from stock.
Some background on the use of Lime in building
Blended lime mortars, plasters and putty’s dry by suction and evaporation and then they carbonate. This is the oldest, most flexible and breathable form of lime used in construction.
Lime is a traditional building material that is strong, flexible and permeable. Buildings built using lime mortar can move and absorb moisture, in comparison cement mortar is rigid and inflexible. When using lime mortar expansion joints can be avoided. Likewise the imperviousness of cement mortar prevents it from absorbing water from the structure whereas lime mortar acts as a kind of ‘wick’, absorbing the moisture and allowing it to evaporate. By absorbing moisture, lime mortar is keeping the masonry dryer and lessening the risk of spalling
Up to the 20th Century building techniques and materials were very different from those employed today. Most buildings were constructed form masonry, brick or cob and were designed to breathe, absorbing moisture then releasing it back again this is particularly important for any structure built without a damp proof course allowing it to evaporate. By absorbing moisture, lime mortar is keeping the masonry dryer and lessening the risk of spalling.
These older buildings needed a versatile and flexible compound to bond the building materials and to create renders and plasters lime was the most common and widely used element for these materials. Lime putty mortars were normally used for bedding and plastering, being a relatively soft mortar it is able to accommodate a certain amount of movement (without cracking) that comes with settlement and seasonal changes in ground conditions. By using lime mortars (which are porous) the building would allow moisture to evaporate, helping to keep a building free of dampness.
Lime is most often used in traditional buildings but modern lime renders and putties are now emerging as viable performance options over cement based products. This is especially true of construction methods that require the building to breathe. By being produced at lower temperatures than cement, lime mortar requires less energy, resulting in 20% less CO2 output. Lime putty absorbs CO2 in the curing process. Non-hydraulic lime absorbs nearly its own weight in CO2, hydraulic lime, around 75%. Lime mortar can be re-cycled, unlike cement. Bricks using lime mortar can be recycled unlike the cement bonded equivalent which can only be used for hardcore. There are two basic types of lime: hydrated lime where an exact amount of water is added, creating a dry powder sold in bags and generally known as hydrated lime or lime hydrate. If more water is added (slaking) the end product is a colloidal gel, commonly sold in plastic tubs and known as lime putty.
Limestone’s which contain clay produce building limes known as hydraulic because they can set under water. The clay impurities contain silica and alumina which forms a more chemically complex and different product. The more clay impurity the faster the set and the harder the mortar. Modern lime products include spray applied renders and insulating renders for example the Ecomerchant Protect System and a wide range of products to meet most construction applications both new and retrofit. Ecomerchant can offer guidance and suitability for all applications. Needless to say all necessary ancillaries are available for you to ensure a complete service.
The Romans discovered that adding volcanic ash from Pozzuoli to a lime putty mortar created a chemical set making the lime mortar hydraulic i.e. it enabled the mortar to set in the presence of water and allowed the Romans to build structures such as aqueducts. Substitute materials have long since been used instead of volcanic ash, hence any burnt clay that reacts with pure limes to create a hydraulic lime set is referred to as a Pozzolan (or Pozzolanic) after the original discovery. If lime putty is kept moist and free from Pozzolans, it will last indefinitely and actually improve with age reducing wastage.
So the original hydraulic lime was in fact a combination of pure lime putty and a Pozzolan that can still be replicated and is usually used these days in the UK to render and point externally or internally on to walls that are inherently damp and require the chemical set.