I test flexural behavior of reinforced lightweight concrete beam. I used two percentage of reinforcement. These ratios are 0,01005 and 0,01508. I got load for 0,01508 ratio double and half load of 0,01005 ratio. I am confused about these results. So, could you kindly help me with the interpretation of these results?
Did you get the rebars from the same manufacturer? Did you use the same details, except the flexural rebars? Spacing and size of the stirrups has a pronounced effect on the flexural capacity. Another reason might stems from the anchored details of the longitudinal rebars. Check token photos/videos from the casting procedure and the used setup (if you have some) to see if everything was fine. Sometimes test setup impose some constrains on some DOFs.
Assuming all parameters are same for two beams except the reinforcement ratio. For lightly reinforced beam, failure would be in tension, there should be more tensile cracks in the beam and a yield plateau may be observed in force-displacement curve.
In heavily reinforced beam, the failure would be in shear or in compression after few tensile cracks. Since concrete is stronger in compression, I assume that heavily reinforced beam shows more load bearing capacity but force-displacment curve would show more britthe behaviour (i.e. no or little yield plateau).
Many reasons could cause such behavior.
Could you describe the failure modes of the beams - crack pattern, the behavior of the beams just before the failure, etc.?
Do both beams were casted at the same time, from the same materials? Whether both beams were investigated at a similar time, with the same load parameters?
What is the ratio respect to the theoretical capacity of each beam?
For more discussion include sketches of the cross and longitudinal section, f'c, fy, stirrups, and any other data that you consider important.
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