Experimental Study on Flexural Behavior of Stone Slabs Strenthened with Forrencent Mortar

Stone slabs are widely used as floor slabs in stone masonry buildings in southeast of China. So these buildings have potential risk against earthquakes, even with low intensity. In order to provide a better reinforcement method for the stone buildings, an idea of stone slabs strengthened with ferrocement mortar was proposed. A two-stage experimental study was carried out to investigate the flexural behavior of specimens.10 stone slabs without strengthening were used for the first stage study. Based on the test results, the failure process and failure models of stone slabs are studied. Also, the flexural behaviors of stone slabs are analyzed. It was concluded that stone slabs exhibited ductility failure mode, the control condition of the permit design load was the cross-section stiffness. Before the failure of stone slabs, cross-section strain distribution along the height was linear, and the plane-section assumption was established. Moreover, the limiting strain method is used in the theoretical study of the flexural behavior of the stone slabs, and the theoretical analysis shows a good agreement with the experiment results. The results can be used to analyze stone structures strength and designs the practical engineering.In order to reinforce research more conform to practical engineering, 13 stone slabs strengthened with ferrocement were taken for the second stage research on the flexural behaviors. The influences of mortar type, reinforcement type reinforcement ratio, and construction mode and reinforcement position on the reinforcement effect are studied. The test results are analyzed, which analyzed the failure modes and impact factors of specimens. It provided an effective experimental basis for proposing the formula of flexural capacity. Test results of flexural behavior of stone slabs strengthened by ferrocement show that: (1) Flexural failure of the stone slab without strengthening shows brittle failure mode, while the failure mode of strengthened stone slabs show ductility failure. (2) Both the flexural load-carrying capacity and the deformation behavior of strengthened stone slabs were improved significantly. And the flexural load-carrying capacity was increased with the increase in reinforcement ratio and the strength of reinforcement. (3) In the five factors, the reinforcement ratio plays the most important role in increasing the flexural behavior. (4) Comparison between the strengthened slabs using commercial polymer mortar and the ones using self-made multiple cement mortar, the cracking moment increased limitedly, while the ultimate moment was almost equal. (5) No deboning failure happened, indicating that the bond behavior between reinforced layer and stone slab is good. (6) Specimens after bending deformation, the strain increment coordination and the cross-section remains satisfied the assumption of plane section.Based on the experimental research and the plane section assumption, the three-phase mechanical characteristics of normal cross section for bending strengthened stone slab are analyzed. Equations of cracking moment and ultimate moment for strengthened stone slabs are proposed. Calculation results showed excellent agreement with test results, and it can be used as a reference for engineering application.