Rammed earth as bi-modulus material. Experimental and analytical investigations through Euler-Bernoulli and Timoshenko beam models

An experimental campaign aimed at defining mechanical parameters of rammed earth is reported. Compressive strength, Young's modulus and Poisson's coefficient are determined on prismatic specimens. Indirect tension tests and three-point bending tests are carried out as well. The size and shape of specimens are accurately controlled to gain consistent results among tests. Interpretation of test results assumes that rammed earth material has two Young's moduli, in tension and compression. In this framework, closed-form solutions for displacements and position of the neutral axis are properly derived from expressions of the displacement field assuming both Euler-Bernoulli and Timoshenko beam models, and hence retrieving the value of Young's modulus in tension. Results show that the assumption of bi-modulus material provides estimations of longitudinal stress reached during three-point bending tests consistent with compression and split tests. Also, the Timoshenko model provides slightly less conservative estimations of Young's modulus in tension.