Experimental study on the effectiveness of short fiber reinforced clay mortars and plasters on the mechanical behavior of adobe masonry walls

The purpose of this study is to improve the behavior of adobe masonry walls using short fiber reinforced mortars and plasters. Two different short fibers, straw fibers, which are commonly used by traditional builders, and a waste rubber fiber, produced by local tire factories, were selected as reinforcement entities for mortars and plasters to investigate experimentally their influences on the mechanical properties of adobe masonry walls. In this direction, several basic tests, including direct compression and diagonal shear tests, were carried out on the adobes, mortars and adobe masonry units with different mortars and plasters. The obtained results indicated that the effects of mortar mixes have significantly impact on the compressive strength of the adobe units in prism specimens. For instance, the adobe prisms using reinforced mortar, mix of mud and short tire fibers, have given the maximum compressive strength, almost twice of the plain one. Nevertheless, the final damage mode was observed promptly and impulsively. It was apparent that using the reinforced mortar with one week-soaked natural straw fibers makes an improvement of the compressive strength and its corresponding strain of adobe masonry prisms by 87% and 18%, respectively. Adding well soaked straw fibers to the clay plaster could even increase the compressive strain of the covered prism specimens by 47%. Carrying the diagonal tensile tests have shown considerable enhancement on the ultimate shear strength and shear strain of the plaster. The adobe masonry Wallette covered with the reinforced plaster by straw fibers would resist 204% and 433% more shear strength and strain, with respect to the uncovered one. Also, use of short rubber fibers reinforced plaster has made 433% and 150% improvement in ultimate shear strength and strain, respectively.