Impact of condensed silica fume on splitting tensile strength and brittleness of high strength self-compacting concrete

Self-compacting concrete (SCC) is a type of concrete that can consolidate itself without external compaction. High-strength SCC (HS-SCC) is becoming more popular having a very broad range of application in Civil Engineering, such as piles, columns of tall buildings and piers for long-span bridges. However, HS-SCC is very brittle that limits its application above. To this, present study aims at mitigating the brittleness of HS-SCC having a fixed water/binder ratio of 0.30 and binder content of 500 kg/m(3) by blending cement with condensed silica fume (CSF). The percentage of CSF that replaced cement was 0-15% by weight. Apart from measuring the brittleness, mechanical property such as splitting tensile and compressive strength, as well as fresh property, such as slump flow, V-funnel time, and L-box passing ability was also obtained. The experimental results indicated that 10% replacement of cement by CSF could effectively decrease the brittleness of HS-SCC and simultaneously increase the 28-day compressive strength. On the other hand, the slump flow of concrete decreased as the content of CSF increased, but nonetheless was able to maintain at above 600 mm, which is a commonly accepted criteria for SCC. Lastly, scanning electron microscope figures showed that the microstructure of concrete and hydration morphology were enhanced by CSF particle.

Automated summary

This study aims to reduce the brittleness of high-strength self-compacting concrete (HS-SCC) by adding condensed silica fume (CSF), which also increases the compressive strength. The addition of CSF improved the microstructure and hydration morphology of the concrete, while maintaining the slump flow within acceptable standards for SCC.