This research advances a method to design and develop a carbon-negative binding material for concrete based on the carbonation of waste metallic iron powder. This approach will result in beneficial utilization of tens of thousands of tons of waste iron powder that are being landfilled, along with permanent sequestration of carbon dioxide as stable carbonates. A conservative estimate of usage of 3 million tons of waste iron powder to produce this novel binder annually will result in CO2 emission reduction in the order of 2.5 million tons and generation of 4 million m3 of concrete. The application scenarios considered here are blast and impact resistance, and electromagnetic shielding, the concurrent attainment of which is unheard of in conventional building materials. Thus this novel material fills a unique niche, making it applicable for sensitive and high-profile structures, data and communication centers, hospitals, and schools. This binder can also be used for strengthening of concrete structures, as blast curtains in shielding critical structures, and in oil and gas industry. The transformational concepts envisaged have the potential to accelerate materials innovation and discovery and provide germination beds for sustainable industrial ventures. Students at the graduate and undergraduate level will be trained, along with many high-school students through on-going workshops on sustainable materials.
This research attempts to redefine the very nature of the strength-imparting medium for concretes. The material design and performance evaluation will be accomplished through coordinated experimental and computational tasks including: (i) composition selection, binder synthesis and characterization, (ii) microstructural and multi-scale mechanical characterization, and (iii) microstructure-guided finite element modeling, to develop structure-processing-property relationships. Specifically, studies will focus on the contribution of multiple chemical species and the processing environment to carbonation and its kinetics. This will be followed by concurrent experimental studies to establish the performance of these binders, considering applications as diverse as blast mitigation and electromagnetic shielding, which will be attained through careful microstructural design. Micromechanical experiments will feed into high-fidelity finite-element models for bulk property prediction of this random heterogeneous composite containing unreacted iron particles, cationic dopants, carbonates of varying density based on reaction kinetics, and pores. Optimization techniques will be used in conjunction with the finite-element model to develop optimal material designs for targeted properties, and thus complete the material design continuum.
