Experimental Study On Flexural Behaviorof Combined Aggregate Concrete Beams' Cross-Section

The Combined Aggregate Concrete which belongs to middle and high-strength concrete refers to the light aggregate, to some extent, instead of common coarse and fine aggregate. The density of it varies between 1800kg/m³ and 2200kg/m³, and the strength of that alters between 40MPa-80Mpa .The Combined Aggregate Concrete has advantages of high strength, small self-weight and good volume stability. It will be in good comparative economic advantages and broad prospects in the long-span structural engineering applications, such as high-rise buildings, bridges and so on. However, the research on it in China is begun just for a short time, and all aspects of theoretical study are also inadequate. This paper includes the following two parts:1,In the experiment, 72 cube and prism test blocks of Combined Aggregate Concrete were made in uniform design methods. Based on experiments, the cube and prism compressive strength of the concrete, which is in different light weight aggregate replacement and different water-cement ratio, is studied in this paper. The compressive strength of Combined Aggregate Concrete affected by the light weight aggregate replacement rate and water-cement ratio is analyzed, as well as the rule ofstrength development with age extension and the age factor.The results show that: (1) The compressive strength reduces with the increasing of light weight aggregate replacement rate and water-cement ratio. The expression of Combined Aggregate Concrete is: f_cu,28 = 78.7 -14.8X₁ -52.4X₂, in which X₁ means light weight aggregate replacement rate and X₂ means water-cement ratio. (2) The age factor of 7 day's of Combined Aggregate Concrete is decresed, but the 14 day's is incresed with the incresing of light weight aggregate replacement rate. The age factor is is decresed with the incresing water-cement ratio.2,The flexural of cross-section of Combined Aggregate Concrete beams', which are in the same strength but in the different ratio of reinforcement, is experimented. Based on experiments, the destruction shape of cross-section is analyzed, as well as the deflection variation and the crack distribution about Combined Aggregate Concrete beams. The calculation method for the flexural capacity of cross-section about the beams is discussed, which will provide reference for further study on Combined Aggregate Concrete.