A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 2003

The fatigue strength of hybrid ferrocement manhole covers and conventional ferrocement manhole covers were studied experimentally by generating S-N curves. Hybrid ferrocement manhole covers were reinforced with commercial steel fibers of 2% by volume and conventional ferrocement manhole covers were reinforced without steel fibers. The skeletal steel and wire meshes were kept constant for both types of covers. High strength mortar of 14 days compressive strength 70 MPa was used of both types of covers. Four specimens from both types of cover were tested under static flexural test with central line load and the mean values of these ultimate static loads were subsequently used for establishing the fatigue test loading. Fourteen specimens from both types of cover were tested under fatigue test. The peak loads were kept at 85%, 80%, 75% and 65% of the ultimate static load respectively. The test results showed that the addition of steel fibers increased the flexural fatigue strength of the ferrocement manhole covers. It was found that the maximum percentages of ultimate static loads causing failure at two million cycles were approximately 67.55% and 64.23% for hybrid and conventional ferrocement respectively. In terms of expected number of cycles to failure, the hybrid ferrocement cover is 120% greater than that of conventional ferrocement cover. The results showed that fatigue strength of ferrocement manhole covers could be improved by the inclusion of randomly oriented short steel fibers in the mortar matrix.