Micro Concrete tiles, mud bricks, pozzolanic cement: EcoSur - Home

The third Sunday of February was different for the ten masonry apprentices from the educational project in Diriamba, Nicaragua. Full of expectations they traveled to a community of Jinotega in the north of the country, with the objective to learn about construction techniques with raw earth and interchange with the local people. After enjoying the beautiful sight of the mountains along the winding northern highway, they arrived in Jinotega to be welcomed by Mateu and Andres, two earth lovers from Spain who want to share their experience, especially with the “Cob” system (construction with raw earth).

The next morning they made the foundations of the first of two houses in the community of “La Quebrada”. To prepare the base for the “cob” walls they collocated fired clay bricks over the foundation to keep humidity away from the earth. During the lunch break lively discussions emerged concerning the construction system, about components and relations (mud, sand and straw), form and dimensions of the walls, forms of the door and window openings, relation between thickness of the walls and their height, (should always be 1/6),  and the method to be implemented were discussed.

They found that filling the 2m x 2m tank with the different layers was interesting, first with a layer of sand, then a layer of mud (with a relation of 40% mud and 60% sand), afterwards with straw covering the whole area and enough water, a procedure they repeated five times to fill the tank. After approximately five hours they began “stamping” of the mixture, and after a while transferred the “Cobs” in wheelbarrows and by hand to the walls of the house.

Further discussion about lime was held on site where they could experience the different qualities, and consider the importance of extinguishing the lime, its hydration and application. Afterwards the young apprentices began piling the “Cob”, and placed and embedded stones with mud to fill the volume. They spontaneously divided the work, while some stamped the mixture others started to form the walls with their bare hands until the first tank of “Cob” was collocated. This spontaneous division of chores and group participation became one of the highlights of this workshop.

They filled the tank again and continued the formation of the walls, with a notable advance at the end of the day, which confirmed that it is a system that can be learned quickly and easily, and with which they could identify . Further motivation came from the enthusiasm and dedication toward the work shown by Patricia and her 12 year old sister who are members of a beneficiary family. The interchange between the apprentices and the local people has been a great experience for these young men from the city. Not only did they take advantage of the technical aspect of the workshop but also learned about a less materialistic perspective of life.

The next day an exposition about plastering with earth and lime, about its different proportions and components, was on the agenda. In plastering with earth they learned that there are several proportions, 8:1-5:3-6:2, depending upon the plasticity of the mixture, and that it is kneaded for eight minutes to guarantee a homogeneous texture between the elements (sand, mud and straw). The lime plaster requires a 1:3 proportion (1 lime, 3 sand) and as much straw as necesssary to obtain a good consistency. They built the walls of a rural school, and all apprentices had the opportunity to practice this new technique. According to one, "working with earth is interesting for all of us, getting to know its different textures, colors and terminations, as well as working a material with our bare hands."

One of the goals of the apprenticeship is to convert theory into praxis, and this workshop provided the opportunity to interact in a rural environment with its real necessities. The young men were able to build “Cob” walls with their own hands after a short introduction of the system, as well as learn about techniques and systems that don’t damage the environment and can involve the beneficiaries in the building of their home.

After five days of working together and applying the principal of “learning by doing” the first workshop about raw earth technologies with raw earth concluded. Besides sharing knowledge, for Mateu and Andres there remains the sweet satisfaction of introducing ten young masonry apprentices into the world of the EcoMaterials and alternative technologies.