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

SusChEM：通过对古罗马混凝土的多尺度研究实现环境可持续混凝土

• 批准号: 1410557
• 负责人: Roya Maboudian
• 金额: $ 49.77万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1410557&HistoricalAwards=false
• 关键词: SusChEM; Environmentally; sustainable; concretes; enabled

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.

非技术描述：基于波特兰水泥水化的混凝土生产是一个能源密集型过程，每年全球二氧化碳排放量的5%-8%令人震惊。古罗马纪念碑和海水港口的混凝土是由火山岩和消石灰制成的，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，化学和机械抗腐蚀性要强得多，生产所需的能源预算也更少。有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结剂的化学性质。该项目的目标是对这种化学反应有一个基本的了解。这项工作的更广泛影响在于它对跨学科科学、社会以及教育和外联活动的积极贡献。这项研究将为我们的资源(能源和清洁水)的更大可持续性和未来高性能混凝土的应用提供指南，以及提高掺入环保补充材料的波特兰水泥混凝土的耐久性，并包括节约淡水资源的海水。从社会的角度来看，这项研究有可能将以波特兰水泥水化为基础的混凝土工业的传统概念转变为自然形成的火山灰沉积所固有的结合机制。这些结果也可能对开发保护古代结构和更新的混凝土结构的改进方法有价值。从经济的角度来看，它将为绿色建筑做出贡献，绿色建筑是国民经济的一个重要增长部门。技术描述：该项目旨在从根本上了解罗马混凝土的水化机制、结合机制、阳离子交换性能和纳米级的机械性能。这项研究基于纳米结构方法，专注于从意大利那不勒斯附近波佐利湾的拜亚努斯海峡防波堤(公元前一世纪)制备的薄而完整的砂浆切片，以及用坎皮·弗莱格里火山灰制备的这些材料的复制品。主要的分析技术包括X射线显微衍射(用于识别晶相)、拉曼光谱(用于结构和振动性能以及结合环境的表征)、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机械性能(模数、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，寿命提高一个数量级以上，并产生专门为减少废物，特别是二氧化碳排放而设计的新工艺，以及比目前工艺更高的能源效率。该项目对教育产生了重大影响，特别是在材料科学、地球科学、考古科学和土木工程等学科领域对研究生和本科生进行了培训。