Experimentally verified atomistic modelling of lime in construction materials

自古以来，建筑行业一直使用石灰基粘合剂来制造砂浆，石膏和抹灰...尽管有这样的历史，仍然缺乏对硬化过程以及这些过程如何影响时间依赖性机械性能的基本理解。此外，与纯石灰相比，含镁的石灰质石灰具有更好的性能，但对其原因的了解有限。石灰基砂浆是许多应用中取代水泥砂浆的理想选择，这些应用中强度较低是一个优势，例如新建房屋，使用有机填料（如石灰-大麻）的建筑形式，以及保护和修复应用。事实上，石灰砂浆在水分介电常数、适应运动的能力、自我修复特性和隔离二氧化碳的能力方面比水泥具有许多优势。与石灰相比，水泥粘结剂的生产温度要高得多，并且在生产过程中会产生大量的二氧化碳排放。原子模型提供了一个独特的机会，可以从根本上探索这些机制，从而阐明开发具有工业重要性的性能的过程。许多现有的和过去的建筑石灰粘合剂的研究都集中在整体性能上，例如通过大规模的整体性能测试，而不考虑原子水平的过程。近年来，水泥工业已经采用水合硅酸盐的原子模型作为理解材料行为的手段。最近的研究表明，石灰晶体的形态和组成可以影响碳酸化过程，并通过关联的机械行为。此外，含镁的钙钛矿石灰在许多方面表现出改进的性能，包括强度发展。碳酸化速率是一个非常重要的问题，因为这可以决定建筑物的建造速度以及相关成本。通过控制组成和形态来提高碳酸化速率并因此提高硬化速率的能力将导致具有更好环境证书的增强产品。在第一种情况下，该建议旨在开发原子模型来描述石灰粘合剂行为的重要方面，并验证这些对实验室样品。原子模型将产生拉曼光谱和X射线衍射图案，用于与实验测量直接比较。这些初始模型将进一步发展，首先研究碳化，然后时间依赖性和塑性力学性能。此外，该研究还将调查含镁石灰中观察到的性能改善的根本原因。预计该项目将在未来几十年为建筑业带来长远利益。在短期内，工业将受益于计划的研讨会和现场访问，这将展示原子模型在石灰制造商中的应用。该项目将通过获得的新知识支持制定强化项目。

Since antiquity the construction industry has been using lime based binders to manufacture mortars, plasters and renders...Despite this history there is still a lack of fundamental understanding of the hardening processes and how these influence time dependent mechanical properties. In addition dolomitic limes, containing magnesium, exhibit enhanced properties when compared to their pure lime counterparts, however there is limited knowledge of the underlying reasons.Lime based mortars are ideal candidates to replace cement mortars in many applications where lower strength is an advantage such as new build housing, forms of construction utilising organic fillers such as lime-hemp, and conservation and restoration applications. Indeed lime mortars offer many advantages over cement in terms of moisture permittivity, ability to accommodate movement, self-healing properties and ability to sequester carbon dioxide. Cementious binders are produced at much higher temperatures compared to lime and have large carbon dioxide emissions associated with their manufacture.Atomistic modelling provides a unique opportunity to probe these mechanisms at a fundamental level thereby elucidating the processes responsible for developing the properties of industrial importance. Many existing and past studies of building lime binders have focused on bulk properties for instance through large scale bulk property testing, whilst not taking into account atom level processes. In recent years the cement industry has employed atomistic modelling of hydrated silicates as a means of understanding material behaviour. Recent studies have demonstrated that the morphology and composition of a lime crystal can influence the carbonation process, and by association mechanical behaviour. In addition magnesium containing dolomitic limes show improved performance in many respects including strength development. Rate of carbonation is an extremely important issue as this can dictate the speed at which a building can be erected and therefore the associated costs. The ability to improve the carbonation rate and therefore hardening rate through control of composition and morphology will lead to enhanced products with better environmental credentials. In the first instance this proposal seeks to develop atomistic models to describe the important aspects of lime binder behaviour and validate these against laboratory samples. Atomistic models will generate Raman spectra and X-ray diffraction patterns for direct comparison with experimental measurements. These initial models will then be developed further to investigate firstly carbonation and then time dependent and plastic mechanical properties. Additionally the research will investigate the underlying reasons for the improved performance observed in magnesium containing dolomitic limes. The project is expected to bring long term benefits to the construction industry over the coming decades. In the shorter term industry will benefit through planned workshops and site visits which will showcase the application of atomistic modelling to lime manufacturers. The project will support the development of enhanced projects through the new knowledge gained.