The typical failure modes of cylindrical samples in splitting tensile strength and beams in flexural strength were observed. It has been found that the sample of the mixes with 100% OPC was split into two parts, brittle failure. When the 12.5% OPC is replaced with silica fume, minor cracks were observed up to the full depth of the samples without splitting into two halves. Is it the ductile behavior in the samples because of silica fume incorporation or any other reason? Need a valuable discussion
Yes, incorporation of silica fume in concrete helps to improve the ductility. But we can analyse the ductility by stress-strain curve. If there is a sudden drop down in curve then it will be brittle otherwise ductility gained if there is minimal drop.
I think strength is not the appropriate parameter for ductility analysis point of view. As we know that high yield strength deformed bars are brittle in comparison to mild steel even it has more tensile strength.
For more details you may refer
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Thank you very much Dr. Shashikant Kumar for a nice discussion
Silica fume reaction with free lime will provide additional C-S_H gel which will bind and ensure pore refinement in concrete. As such the discontinuity and capillary voids are filled up creating more cohesive concrete. This will have more deformation before failure indicating ductile behavior than normal concrete.
In any case load deformation curve is the only parameter to assess the ductile or brittle failure mode.
Thank you very much, Dr, Om Prakash Chhangani for a valuable information
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