Nanoscale Characterization of Expansion Due to Delayed Ettringite Formation

Tennessee Technological University, Cookeville TN

Investigators

Abstract

The primary objective of this research is to investigate the nano- and micro-scale mechanisms of late age ettringite formation and how these mechanisms relate to macro-scale expansion in concrete materials, enabling possible mitigation strategies for damage due to the late age formation of ettringite. This research will examine the chemical and physical structure of the reactants and products, as well as the pore structure evolution, involved in the process of late age ettringite formation and subsequent expansion and cracking. A more thorough understanding of the crystalline pressures induced on the microstructure will result by refining existing models with analytical techniques such as nanoindentation and residual stress analyses. Concrete is the most widely used engineering material in the world, yet is still poorly understand in many regards. The prevention of delayed ettringite formation, which is known to cause concrete cracking, would significantly improve the infrastructure life span of the United States and abroad. Educational activities will include traveling to local middle and high schools to provide hands-on experiments that give the students a real-life view of how engineering is an important part of the modern world. Local primary school groups will be invited to campus to participate in hands-on learning experiences at Tennessee Tech?s STEM Center. In addition to the educational activities, a residual stress analysis workshop is proposed at the end of the project to disseminate the strong background in this field at Tennessee Tech to other cement and concrete researchers; thus, expanding beyond traditional K-12 outreach.