A New Sustainable Binder for Concretes Based on Carbonation of Waste Metallic Iron Powder

本研究提出了一种基于废金属铁粉碳化的混凝土碳负粘结材料的设计与开发方法。这种方法将有益地利用正在被填埋的数万吨废铁粉，同时永久封存二氧化碳作为稳定的碳酸盐。保守估计，每年使用300万吨废铁粉来生产这种新型粘结剂，将导致二氧化碳排放量减少约250万吨，产生400万立方米混凝土。这里考虑的应用场景是抗爆炸和抗冲击，以及电磁屏蔽，这在传统建筑材料中是闻所未闻的。因此，这种新型材料填补了一个独特的利基市场，使其适用于敏感和高调的结构、数据和通信中心、医院和学校。这种粘结剂还可用于混凝土结构的加固，作为屏蔽关键结构的防爆帷幕，以及石油和天然气工业。设想的变革性概念有可能加速材料创新和发现，并为可持续工业企业提供萌芽床。研究生和本科生以及许多高中生将通过持续不断的可持续材料讲习班接受培训。这项研究试图重新定义混凝土强度传授介质的本质。材料设计和性能评估将通过协调的实验和计算任务完成，包括：(I)成分选择、粘结剂合成和表征，(Ii)微观结构和多尺度机械表征，以及(Iii)微结构引导的有限元建模，以建立结构-加工-性能关系。具体地说，研究将侧重于多种化学物种和加工环境对碳化及其动力学的贡献。随后将同时进行实验研究，以确定这些粘结剂的性能，考虑到爆炸缓解和电磁屏蔽等各种应用，这些应用将通过仔细的微结构设计实现。细观力学实验将提供给高保真有限元模型，用于预测这种随机的非均质复合材料的体积性能，该复合材料包含未反应的铁颗粒、阳离子掺杂、基于反应动力学的不同密度的碳酸盐和气孔。优化技术将与有限元模型结合使用，以开发针对目标特性的最佳材料设计，从而完成材料设计连续体。

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.