Flexural capacity and failure trend of fiber and steel reinforcement reinforced cement stabilized rammed earth beams

Due to the low flexural strength of rammed earth, it is prone to flexural cracks under horizontal loads, necessitating the development of novel structural measures to enhance its flexural capacity. This study introduced the reinforcement of rammed earth structures with embedded steel reinforcement to improve their flexural performance. A series of two-point loading tests were conducted on 12 rammed earth beams to investigate the effects of polypropylene fiber content and steel reinforcement ratio on the deflection, cracking load, ultimate load, flexural toughness, and failure modes of the beams. Based on the assumption of the plane section, a design formula for the flexural capacity of reinforced rammed earth beams was proposed and validated against experimental results. The findings indicate that the addition of polypropylene fibers increased the cracking load, deformation capacity, and flexural toughness of the rammed earth beams by 14.8 %, 44.2 %, and 105.6 %, respectively. In contrast, the inclusion of steel reinforcement significantly enhanced the ultimate load, deformation capacity, and flexural toughness by 596.3 %, 607.0 %, and 4543.2 %, respectively, transforming the failure mode from brittle fracture to ductile flexural failure. The proposed formula was validated and can be effectively used to calculate the flexural capacity of reinforced rammed earth beams.