Investigation on the Interfacial Transition Zone in Nano Modified Concrete

Abstract

The interfacial transition zone (ITZ) is the region that is the weakest link in determining the mechanical behavior and long-term durability of concrete. The ITZ is inherently porous in conventional concrete and generally is more susceptible to microcracks, reducing the structural performance. In this study, the effect of nano silica modification on the characteristics of the ITZ of concrete is studied based on the experimental program. Different amounts of nano silica replacement was used in the concrete to make the mixtures, which were all prepared and cured in the same way. For assessing effectiveness of nano modification the experimental methodology involved compressive strength, split tensile strength, flexural strength, water absorption and sorptivity test and ultrasonic pulse velocity test. Indirect assessment of ITZ improvement was conducted by correlating mechanical performances with durability parameters, such as permeability-related properties and internal concrete quality. The results indicated that addition of nano silica had a positive effect on the concrete performance by improving the mechanical properties such as compressive, tensile and flexural strengths, but also the water absorption and sorptivity, and the UPV value, thus the most dense and uniform ITZ. The results verify that modification with nano materials is effective in enhancing the strength of the aggregate–paste bond which results in increased overall structural integrity and durability. This study gives useful guidelines for the improvement of high-quality, long-lasting concrete for contemporary civil engineering uses.