Experimental investigation of engineered geopolymer composite for structural strengthening against blast loads

Abstract

The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures. Engineered geopolymer composite (EGC) is a promising material featured by eco-friendly, fast-setting and strain-hardening characteristics for emergent strengthening and construction. However, the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain. In this study, laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability, dry shrinkage, and mechanical properties in compression, tension and flexure. The experimental results showed that EGC containing PE fiber exhibited suitable workability, acceptable dry shrinkage and superior mechanical properties compared with other types of fibers. After that, a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements. The tests include autoclaved aerated concrete (AAC) masonry walls subjected to vented gas explosion, reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion. It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios. For AAC masonry walls and panels, with the existence of EGC, the integrity of specimens could be maintained, and their deflections and damage were significantly reduced. For plain concrete slabs, the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.