Untreated clay was one of the earliest building materials to be used by humankind. The oldest examples of this can be found in houses in the Near East dating from between 11,000 and 12,000 years ago, while earthy material mixed with plants and pebbles to make them stronger has also been found in certain archaeological deposits from 1,400BC in Sardinia, Italy.
Spanish and Scottish researchers more recently added wool fibers to the clay material used to make bricks and combined these with an alginate, a natural polymer extracted from seaweed. The result is bricks that are stronger and more environmentally-friendly but mechanical tests carried out also showed the compound to be 37% stronger than other bricks made using unfired stabilized earth, according to a study published recently in Construction and Building Materials.
Bricks made with wool. Photo: Galán-Marín et al.
The clay-based soils were provided by brick manufacturers in Scotland, which was also the source of the wool, since the local textile industry cannot use everything it produces. "The aim was to produce a material suitable for adverse climatic conditions, such as the specific ones in the United Kingdom," the authors explain.
Advantages of environmentally-friendly bricks
The researchers studied the effect of reinforcing various soil types with sheep's wool, and arrived at various conclusions. "These fibers improve the strength of compressed bricks, reduce the formation of fissures and deformities as a result of contraction, reduce drying time and increase the bricks' resistance to flexion."
This piece of research is one of the initiatives involved in efforts to promote the development of increasingly sustainable construction materials. These kinds of bricks can be manufactured without firing, which contributes to energy savings. According to the authors: "This is a more sustainable and healthy alternative to conventional building materials such as baked earth bricks and concrete blocks."
"The objective was to produce bricks reinforced with wool and to obtain a composite that was more sustainable, non-toxic, using abundant local materials, and that would mechanically improve the bricks' strength," Carmen Galán and Carlos Rivera, authors of the study and researchers at the Schools of Architecture in the Universities of Seville (Spain) and Strathclyde (Glasgow, United Kingdom), told SINC.
Citation: C. Galán-Marín, C. Rivera-Gómez, J. Petric, 'Clay-based composite stabilized with natural polymer and fibre', Construction and Building Materials, Volume 24, Issue 8, August 2010, Pages 1462-1468
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