Sítio organizes workshops on Lime Plastering with Engineer Fernando Cartaxo and Fradical.
Next Workshop – Dates to be announced
Aerated Lime
The history of this material dates from the dawn of the history of man. It was still in pre-historical times that man began producing lime – there where found traces of its use with more than 10 000 years. This material is part of the group of the first chemical transformations that we were able to dominate. Since then it’s present in many cultures around the world and in Portugal it is widespread throughout most of the country. It was used for millennia as a disinfectant, as a bonding agent and as soil treatment for agriculture. Today, if we exclude oil and its derivatives, this is the most produced chemical in the world – 300 million tons annually.
In less developed economies a large proportion of this material is still use for construction, especially as mortar for masonry and as plastering or coating. In highly industrialized economies, like ours, the proportion of lime applied to construction is extremely low. Cement now occupies that space.
This new material has several problems, at an ecological level – requires large amounts of energy to be produced and is not recyclable – at an economic and social level – needs a major centralization of resources and capital to be produced – and at a technical level – short-life (it’s chemical cure their never stops so it deteriorates with the passage of time), releases salts over time which are damaging to buildings, it has a strong capillary action and because of its rigidity it tends to crack.
It was the usage of cement renderings, for instance, that created to the need for the introduction of solutions such as latex and plastic paints that, in turn, also have serious consequences for the environment and for the health and comfort of buildings.
But lime can and should be rescued. Using traditional recipes and developing new research it is now possible to obtain solutions that easily surpass the performance of cement with such a great environmental comfort and aesthetic quality that they render the use of any other type of finishing totally useless.
As a constructive solution this material stands out in several ways:
Lime is an appropriate material – Even if it results from the burning of limestone (CaCO3) at temperatures from 825 to 900 °C the production of lime can be made on a local scale with simple technology. Its application, although involving some specific knowledge, is easy to learn.
Lime is a very versatile material – The lime can be used for many purposes. In construction it can be used as mortar, ordinary plastering, waterproofed plastering, paints, glues, stabilizer for mortar and earth bricks, among many other applications. Lime allows you to add other materials incorporating new physical and chemical features (eg. By adding pozzolans you can get sturdy concrete as that used by Romans in the construction of the Pantheon, or adding a byproduct of olive-oil production you can get a totally hydrophobic mix that maintains a high permeability to water vapor. This material is also compatible with a large number of constructive solutions including building with raw earth.
Lime is an environmentally friendly material – Even with the combustion, lime’s embedded energy is relatively low. The same amount of Carbon Dioxide (CO2) released during the burning process (excluding that from the fuel) is reabsorbed in the curing process. Plus, lime is a fully recyclable material and capable of incorporating, for the formation of composite materials, byproducts of other industrial activities – that are sometimes difficult to eliminate. Lime can also be produced from renewable raw materials (eg from the shells of some mollusks).
Lime is not toxic – When applied as a plastering, because it is not a vapor barrier, lime provides a quality environment balancing the moisture in the air and preventing respiratory diseases. It is an entirely natural material totally compatible with human health.
Lime is a hard and durable material – In the curing process, the absorption of carbon dioxide (CO2) causes the lime to slowly turn to it’s source material, limestone, creating a monolithic material that is both extremely durable and aesthetically very interesting. It also grants to mixes a low elasticity modulus turning them very resistant to cracking.
These characteristics grant lime a great strategic interest in the search for solutions that promote the ability of individuals and communities to manage their own built environment, while maintaining an harmonious existence in the ecosystem we inhabit.
Control over this material opens up a wide range of possibilities that can be applied in the creation of jobs and economic relations at the local level, working in a sustainable, resilient and creative way.
The Teacher
Fernando Cartaxo is Civil Engineer graduated from Instituto Superior Técnico in 1976. In addition to extensive experience in project and building site management he has worked on detailed studies on lime since 2001. He’s since been involved in research on the composition and manufacture of lime paste, pozzolamic. He co-authored the communication “Characterisation of hydrofuged lime Mortars for use on walls, ancient buildings” presented in 2006 at the 7th International Masonry Conference.
In 1996 he founded FRADICAL, Fábrica de Transformação de Cal, Lda. that is dedicated to the production and marketing of various lime products.
He also co-authored the European patented solution ECO-ETICS Suberlyme
The workshop
This workshop’s goal is the transmission of knowledge about lime and all its possibilities. Special attention will be given to its striking possibilities as a plastering solution. This includes fully waterproofed plastering solutions. Theoretical and practical components will be balenced trough out the workshop. Together, these two learning moments will allow that, at the end of this workshops, the students have the ability to understand and apply this material.
The workshop will have three major stages:
1 – Transmission of theoretical knowledge on lime a pozzolans.
2 – Testing various plastering solutions (samples)
3 – Applying the acquired knowledge by plastering an adobe building built in a previous workshop. To learn more about this building click here.
This workshop targets all those (with or without training in construction) who have the curiosity to better understand this material.