Simple methods and tools to determine the mechanical strength of adobe in rural areas

In rural areas, especially in less economically developed countries (LEDCs), it is very difficult to access to data on building materials, to properly design the buildings. In particular, the raw earth is difficult to characterize, even where it is commonly used. Its parameters vary greatly depending on the manufacture techniques and on the composition of particle size of the soil used, different from place to place. To design raw-earth structures it is crucial to know a value of compressive strength to use in calculations. Unfortunately, in many places of the world, it is not possible to define these values for unfired clay bricks (fb,r,mean) involving laboratory equipment normally used by official certifiers. For this reason, the crushing tests of specimens have to be performed using simple tools, that can be easily carried out even in places where advanced technologies are lacking. The research has been organized in the following phases: to design and implement two test tools (Nutcracker’s method and simple lever method); to test an adequate number of specimens suitable for the purpose, using both laboratory instruments and the two implemented tools; to compare the obtained results, in order to assess the reliability of the instruments and the followed procedure to obtain an actually usable value of fb,r,mean. The experimental trials have led to the following conclusions: the Nutcracker’s method is perfectly suited for the intended purpose; on the contrary the simple lever method has proved to be not usable in practice.