SusChEM: Environmentally sustainable concretes enabled by multiscale investigation of ancient Roman concretes

非技术描述：以波特兰水泥水化为基础的混凝土生产是一个能源密集型的过程，占全球每年二氧化碳排放量的5-8%。古罗马纪念碑和海水港口的混凝土是由火山岩和水合石灰制成的，与传统的波特兰水泥混凝土相比，它们的二氧化碳足迹要小得多，具有更强的化学和机械抗腐性，而且生产所需的能源预算也更少。2000年历史的混凝土的环境可持续性的秘密可以追溯到砂浆粘合剂的化学性质。该项目的目标是获得对这种化学的基本理解。这项工作的广泛影响在于它对跨学科科学、社会、教育和推广活动的积极贡献。这项研究将为我们的资源（包括能源和清洁水）的更大可持续性提供指导，并为高性能混凝土的未来应用提供指导，以及提高波特兰水泥混凝土与环保补充材料混合的耐久性，包括保护淡水资源的海水。从社会的角度来看，该研究有可能将基于波特兰水泥水化的混凝土工业的传统概念转变为自然形成的火山灰沉积物固有的结合机制。研究结果也可能对开发保护古代建筑和近代混凝土结构的改进方法有价值。从经济角度来看，这将有助于“绿色”建设，这是国民经济的重要增长部门。技术描述：本项目旨在对2000年历史的罗马混凝土胶凝成分的水化机制、结合机制、阳离子交换特性和纳米级力学特性有一个基本的了解。这项研究是基于纳米结构的方法，重点研究从意大利那不勒斯附近的Pozzuoli湾的Baianus Sinus防波堤（公元前1世纪）制备的薄而完整的砂浆片，以及用Campi Flegrei火山灰制备的这些材料的复制品。主要的分析技术包括x射线微衍射（用于识别晶体相）、拉曼光谱（用于结构和振动特性以及键合环境表征）、核磁共振（用于Si-O和Al-O键合环境）、高分辨率透射电子显微镜（用于详细的纳米结构研究）、纳米压痕(以纳米级分辨率评估这些相的力学特性（模量、硬度、强度）。以及砂浆复制品的工程强度和耐久性测试。预计这项研究将导致高性能混凝土的新配方，其使用寿命将提高一个数量级以上，并在专门设计的新工艺中减少废物，特别是二氧化碳排放，并且比目前的工艺具有更高的能源效率。这个项目的一个重要影响是在教育方面，特别是在几个学科领域培养研究生和本科生：材料科学、地球科学、考古科学和土木工程。

NON-TECHNICAL DESCRIPTION: Production of concrete based on Portland cement hydration is an energy intensive process responsible for a staggering 5-8% of the annual global CO2 emissions. The concretes of ancient Roman monuments and seawater harbors, produced from volcanic rocks and hydrated lime, have a far smaller CO2 footprint than conventional Portland cement concretes, far greater chemical and mechanical resistance to decay, and take a smaller energy budget to produce. The secret to the environmental sustainability of the 2000-year old concretes is traced to the chemical nature of the mortar binder. The goal of the project is to gain a fundamental understanding of this chemistry. The broader impact of this work lies in its positive contributions to interdisciplinary science, society, and educational and outreach activities. The research will provide guideposts for greater sustainability of our resources (both energy and clean water) and future applications to high performance concretes, as well as to increased durability of Portland cement concretes blended with environmentally-friendly supplemental materials, and including seawater, which conserves fresh water resources. From a societal perspective, the research has the potential to transform traditional concepts of the concrete industry based on Portland cement hydration, to binding mechanisms inherent in naturally-occurring volcanic ash deposits. The results may also be of value in developing improved methods for conservation of ancient structures and more recent concrete structures. From an economic perspective, it will contribute to "green" construction, an important growth sector of the national economy. TECHNICAL DESCRIPTION: This project aims to gain a fundamental understanding of the hydration mechanisms, binding mechanisms, cation exchange properties, and nanoscale mechanical properties of 2000-year old cementitious components of Roman concretes. The research is based on a nanostructural approach that focusses on thin, intact slices of mortars, already prepared from the Baianus Sinus breakwater (first century BC) in Pozzuoli Bay near Naples, Italy, and reproductions of these materials prepared with Campi Flegrei volcanic ash. The primary analytical techniques include X-ray microdiffraction (to identify crystalline phases), Raman spectroscopy (for structural and vibrational properties and bonding environment characterization), nuclear magnetic resonance (for Si-O and Al-O bonding environments), high-resolution transmission electron microscopy (for detailed nanostructural studies), nanoindentation to assess mechanical properties of these phases (modulus, hardness, strength) with nanoscale resolution, and engineering strength and durability testing for the mortar reproductions. It is anticipated that this research will result in new formulations of high performance concretes with a lifetime improvement of over one order of magnitude, and in new processes designed specifically for reduced waste product, especially CO2 emissions, and for much higher energy efficiency than current processes. A significant impact of this project is in education, in particular by training graduate and undergraduate students in several disciplinary areas: materials science, earth science, archaeological science, and civil engineering.