Effect of steel fibres and nano silica on fracture properties of medium strength concrete

Abstract

This study presents the fracture properties of nano modified medium strength concrete (MSC). The nano \nparticle used in this study is nano silica which replaces cement about 1 and 2% by weight, and the micro steel fibers \nare added about 0.4% volume of concrete. In addition to fracture properties, mechanical properties, namely, \ncompressive strength, split tensile strength, and flexural strength of nano modified MSC are studied. To ensure the \ndurability of the MSC, durability studies such as rapid chloride penetration test, sorptivity test, and water \nabsorption test have been carried out for the nano modified MSC. From the study, it is observed that significant \nperformance improvement in nano modified MSC in terms of strength and durability which could be attributed due \nto the addition pozzolanic reaction and the filler effect of nano silica. The incorporation of nano silica increases the fracture energy about 30% for mix without nano silica. Also, size independent fracture energy is arrived using two \npopular methods, namely, RILEM work of fracture method with P–u tail correction and boundary effect method. \nBoth the methods resulted in nearly the same size-independent GF irrespective of the notch to depth ratio of the same specimen. This shows evidence that either of the two procedures could be used in practice for analysis of \ncracked concrete structures.