The nopal, a very Mexican material
Opuntia Ficus-indica, or Common nopal, is a species native to Mesoamerica whose multiple applications and properties have been used in architecture since the pre-Hispanic era. Recently, several working groups in our country are investigating other possible promising uses for nopal in the construction industry.
The use of natural materials in the construction is a millenarian inheritance, and its development in Mexico originates in the ancient pre-Hispanic civilizations that perfected the processes for its obtaining and application. Among the most common is the nopal mucilage (Opuntia Ficus-indica), since its properties have since been used to modify and improve the characteristics of some materials used in construction and also as a coating.
The Teotihuacans, for example, used it as a binder and added it to stuccoes and murals, or used it in the preparation of plasterings in walls, so that they acquired some degree of hardness and impermeability. Later, during the colonial period, Nopal was used in lime-based mixes, which were added yolk and egg white, cotton, as well as other elements of animal origin: hair, hair, ox blood, bull, pork.
For this reason, and for some years, has been experimented with the use of this material in the field of conservation-restoration, where, to find compatible and appropriate alternatives with different construction systems, were replicated Colonial procedures. Its main use has been as an additive in lime mortars, since it has been shown to improve its plasticity and curing properties; In addition the Mucilage − a biopolymer coagulant −, is useful to waterproof, to cover pores or to reheal. In Adobe Constructions both the mucilage and nopal gum are used as consolidating or fixing with good results.
The history of the nopal in the constructive procedures continues, since recently, and before the rainy season in the country, students of the Instituto Tecnologico Superior de Huichapan (ITESHU) announced a proposal of waterproofing for the Construction developed from Nopal. Its advantage, in addition to the low cost, is the positive impact with the environment.
The prototype is a cactus Slime formula combined with adhesive mortar — or pegazulejo — and white cement that, in addition to being adaptable to any construction material, allows to add different types of colorants, depending on the user's needs. For one litre of waterproofing, 800 milliliters of nopal slime, 240 grams of pegazulejo and 280 of white cement are used. It is applied as any waterproofing of those that exist in the market.
Another work team consisting of researchers from the Mexican Institute of Transport (IMT) and the Marist University of Queretaro, A.C. Presented the results of a project that analyzed the properties of nopal to improve the durability of cement-based materials, mortars and concrete.
The project sought to identify the properties of nopal, both dehydrated and colloid (BABA) or mucilage, to determine how it can contribute to improve these materials, grouts, mortars and concretes, as well as their influence on the properties Electrochemistry of embedded steels used in construction.
In this regard, the researcher of the IMT, Andrés Antonio Torres Acosta, explained that this initiative seeks to contribute to the sustainability applied to the construction materials industry, particularly the cement factories and the steel mills, which have been Marked as large emitters of carbon dioxide (CO2) to the atmosphere.
After the laboratory research processes, it could be concluded that the additions of nopal and dehydrated aloe decrease the workability of pastes and mortars, apparently, because they coagulate part of the mixing water, in addition to the resistance of this Material increases with age. As for steel, the electrochemical values obtained in the tests, it was found that the additions of dehydrated nopal function, apparently, as a corrosion inhibitor of this material, in addition to preventing the formation of bites in solutions Alkaline.
On the other hand, the researcher at the Marist University of Queretaro, Alejandra Díaz Cruz, hinted at the next phase in the use of nopal, by pointing out that the research work focused on his study, go hand in arm with the aim of promoting The industry of this plant, given the climatic conditions of the country and the facilities for its cultivation. "What is wanted is to detonate the production of nopal and improve its quality using biotechnology. Both in the Michoacan University of San Nicolás de Hidalgo and in the CIIDIR of Oaxaca there are groups of researchers that analyze how to synthesize and produce the mucilage, analyzing factors such as the age of the plant, seasons of harvest and temperatures to obtain a Product of a constant quality. "