Experimental Research On Flexural Behavior Of Lightweight Concrete Beams

Lightweight concrete has light weight-high strength, thermal insulation, good earthquake resistant performance, high durability and remarkable economic benefits characteristic, therefore its application on bridge engineering, tall buildings and marine engineering increases day by day. Furthermore it's also an environmental protection building materials. This preeminence will be highlight as the sustainable development strategy was carried out. However, no longer can the research results on the mechanical properties of lightweight concrete be content to the new requirements during application. Accordingly, experimental research focusing on the mechanical properties of high-strength reinforced lightweight concrete beams, have the important theories and realistic meaning.In this paper, based on the experiment of lightweight concrete beam specimens, fiber lightweight concrete beam specimen and normal-weight concrete specimens, the mechanical properties of lightweight concrete beam under one-way loading, including the failure pattern, normal section bearing capacity, the changing regularity for deflections and the development of cracks are observed and analyzed. Comparisons are made among the different specimens on the respects above. The influence factors on load-deflection curves and maximum crack width under service load are also analyzed in this paper. The test results indicate: bearing capacity of lightweight concrete beam is less than the one of normal-weight concrete beam under similar conditions. Under same loads, the mid-span deflections of lightweight concrete beam are more than the ones of normal-weight concrete beam, the mean crack spacing and maximum crack width are less than the ones of normal-weight concrete beam. Meanwhile, it is a reasonable and feasible method to mix polypropylene fiber into lightweight concrete which is able to improve the performances on bearing capacity, deformation and crack width.According to theoretical analysis and experimental data, formulas for the maximum crack width under short-term load of lightweight concrete members and fiber lightweight concrete members , are proposed. By comparison with the experimental results, it is indicated that the predicted values are reliable. This paper aims to providing scientific basis for the practical application of lightweight concrete beams on port projects, dock projects, etc.