Effect of date palm fibers on the stability of a mixture of dune sand and clay, intended for the manufacture of compressed earth brick (CEB)

The disadvantage of traditional use of earth in construction is its vulnerability to shrinkage cracking, impairing durability. This study aims to optimize the dimensional stability of a mixture of reconstituted earth from 50% dune sand and 50% clay, with the addition of 0.5% by mass, of 15 mm long date palm fibers. Test specimens prepared in 60X60X35 mm, samples are compressed at the Proctor optimum energy. Undrained direct shear tests are carried out at the Casagrande box under vertical loads inducing stresses (Ϭ), successively of 50 kpa, 100 kpa and 150 kpa. The test intervals are one hour, 24 hours and 48 hours after the preparation of the specimens. The shear rate is set at 0.5 mm/min, and the corresponding shear stresses (Ꞇ) are recorded at the indicated intervals. After 48 h, the results obtained for the intrinsic parameters at failure indicate an improvement in the torque; internal cohesion (C) and friction angle (Ҩ), compared to the control specimens of 20% for internal cohesion and 40% for the internal friction angle. A regression of cohesion is observed at the early ages of the specimens in reinforced mixture. This is due to the effect of fiber absorption on adhesion with the matrix. These results show that the incorporation of FPDs in the proposed mixture promotes internal stability and thus improves the quality of the earth for the manufacture of compressed earth block “CEB”.