Investigation of the efficacy of nano-silica on mechanical properties of Green-Engineered Cementitious Composite (GECC) containing high volume natural zeolite

This research was conducted to optimize and improve the properties of Green-Engineered Cementitious Composite (GECC) with a high volume natural zeolite via adding micro-and nano-silica. The base mix design contained natural zeolite with a zeolite-to-cement weight ratio (Z/C) of 2.4. In the other three mix designs, micro-silica replaced zeolite by a constant amount of 5%, and nano-silica replaced zeolite by 1, 2, and 3% separately. Then, the mechanical properties and microstructure of the prepared specimens were investigated at different ages. The results indicated that the nano-silica improved the mechanical properties, strain hardening, and flexural toughness index of GECC. In this regard, by adding 2% nano silica, the 28-day compressive strength and maximum flexural stress improved by 6 and 19%, respectively. The scanning electron microscopy (SEM) images showed that nano-silica enhanced the fiber/matrix interaction, such that in tension, the fibers experienced elongation and rupture when being pulled out from the matrix, which suggests better fiber/matrix cohesion. Moreover, processing the backscattered electron (BSE) images using Cumulative greyscale histogram showed that nano-silica decreased porosity around fibers in the interfacial transition zone. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study aimed to optimize and improve the properties of Green-Engineered Cementitious Composite (GECC) with a high volume natural zeolite by adding micro-and nano-silica. The results showed that nano-silica improved the mechanical properties and flexural toughness index of GECC, enhancing the fiber/matrix interaction and reducing porosity around fibers in the interfacial transition zone.