Novel low energy high performance mortars for the construction industry

砌体建筑，包括粘土砖和混凝土砌块，依靠10毫米的砂浆接缝将单元粘合在一起。在英国，每年大约生产5000万平方米（墙面积）的烧制粘土砖和6000万平方米的混凝土块，需要大约15亿升的砂浆。砂浆在砌体建筑中的作用是在单元之间提供均匀的床，将单元粘合在一起以提供抗弯强度并密封接缝以防止雨水渗透。越来越多的建筑行业意识到，液压石灰砂浆非常好地满足了这些要求。与更广泛使用的水泥砂浆相比，石灰砂浆的一个显著优点是减少了40%的二氧化碳排放，二氧化碳是一种重要的温室气体。提出的工作是开发低能高性能砂浆，使用一种新的生石灰干燥技术来制备骨料，在混合物中加入外加剂，并延长粘结剂阶段，包括火山灰和替代低能水泥。本提案旨在研究和开发生石灰添加到细骨料中作为干燥砂的手段。该方法依赖于水的化学结合产生氢氧化钙和相关的热生产。然而，所需生石灰的量将随砂的含水量和所需的砂浆混合物而变化。随着砂浆混合设计变得更稀薄（强度更低），将需要更多的生石灰来干燥沙子。最稀的混合料将需要大量生石灰，同时减少液压石灰成分。这将限制砂浆的潜在工程性能，除非对其成分进行修改。因此，这项研究将调查可能的修改，包括使用外加剂，如减水剂、火山灰，以及更有活力的水力粘合剂，如罗马水泥。当前版本的砌体结构设计规范不包括石灰砂浆砌体的设计数据。结合低能量迫击炮的开发，拟议的工作将设法解决这一数据的缺乏。提出的研究方法包括干混低能砂浆的试验研究，包括搅拌过程中石灰对干湿砂的熟化效率的研究、砂浆的微观结构分析和低能砂浆砌体性能的研究。试验研究将由砌体性能的数值分析和砌体寿命周期的比较分析来支持。砂干燥和砂浆性能的研究将主要在布拉德福德大学和布里斯托尔大学进行，而砌体性能和生命周期分析的实验和数值研究将主要在巴斯大学完成。目前的提案在两个重要领域扩展了以前的工作：首先，它将扩大可用的低能量迫击炮的范围；其次，建议的工作将检查这些石灰在结构砌体中的性能，以便工程师，建筑师和建筑商可以放心地使用这种材料。

Masonry construction, including both clay bricks and concrete blockwork, relies on 10 mm mortar joints to bond the units together. In the UK around 50 million m2 (wall area) of fired clay bricks and 60 million m2 of concrete blocks are produced every year, requiring around 1.5 billion litres of mortar. The functions of mortar in masonry construction are to provide an even bed between units, bond units together to provide flexural strength and seal joints against rain penetration. Increasingly the construction industry is realising that hydraulic lime mortars fulfil these requirements extremely well. One significant benefit of lime mortars, in comparison with more widely used cement mortars, is a 40% reduction in carbon dioxide emissions, a significant greenhouse gas.The proposed work is to develop low-energy high-performance mortars using a novel quicklime drying technique for the aggregates, the inclusion of admixtures with the mix and the extension of the binder phase to include pozzolanas and alternative low energy cements. This proposal aims to investigate and develop the use of quicklime addition to the fine aggregate as the means to dry the sand. The approach relies upon both the chemical combination of water to yield calcium hydroxide and the associated heat production. However, the amount of quicklime required will vary with sand moisture content and desired mortar mix. As the mortar mix designs become leaner (lower strength), increased quantities of quicklime will be required to dry the sand. The leanest mixes will require significant quantities of quicklime with an associated reduction in the hydraulic lime component. This will limit the potential engineering properties of the mortar unless modifications are made to its composition. The study will therefore investigate possible modifications, including the use of admixtures such as water reducers, pozzolanas, as well as more energetic hydraulic binders such as Roman cement. Current editions of the structural design codes for masonry do not include design data for lime mortared masonry. In combination with the development of low-energy mortars, the proposed work will seek to address this lack of data.The proposed research methodology comprises experimental investigation of dry mix low-energy mortars, including the study of efficiency of lime slaking to dry wet sand during the mixing process, micro-structural analysis of mortars, and investigation of low energy mortared masonry properties. Experimental studies will be supported by numerical analysis of masonry properties and comparative life cycle analysis of masonry. Research of sand drying and mortar properties will primarily be undertaken at the Universities of Bradford and Bristol, whilst experimental and numerical investigation of masonry properties and life cycle analysis will primarily be completed at the University of Bath. The current proposal extends previous work in two important areas: firstly it will extend the range of available low energy mortars; and, secondly, the proposed work will examine the performance of these limes in structural masonry so that engineers, architects and builders can use the material with confidence.