Development of 3D Printable Strain Hardening Cementitious Composites for Bridge-Related Applications

Strain hardening cementitious composites (SHCC) possess exceptional crack width control, which has been utilized to improve the durability of various concrete structures. Recently, several studies have reported the development of 3D printable SHCC. However, the performance-based design of a 3D printable SHCC, specifically for a bridge-related application, has not been reported. This paper describes a framework for developing an SHCC suitable for extrusion-based 3D printing while achieving the mechanical properties and crack width control needed to mitigate end-cracking in a prestressed concrete bridge girder. The framework proposes the use of finite element analysis to estimate the properties of SHCC needed for the given application and iterative modification of the mix to fulfill the strength and printing requirements. The proposed framework consists of various stages, and the initial stage of rheological modification of a baseline SHCC is discussed in this article. Sixteen variations of the baseline mix were developed by varying the proportions of viscosity modifying agent (VMA) and high range water reducing admixture (HRWRA). The flow properties of trial mixtures were evaluated using the flow table test, fiber dispersion was evaluated through manual inspection of the mix, and extrudability and buildability were examined qualitatively using a hand-operated extruder. Four suitable mixtures were identified based on preliminary examination which will be further optimized and evaluated in future work.