The overall aim of this research was to improve scientific knowledge of the reactions that occur in, and the resulting properties of, lime mortars. Various aspects of lime mortar were Initially investigated. Firstly, Raman spectroscopy was used to study the hydration of lime which provided an insight into the phases present and their rate of hydration. Secondly, lime was produced from the calcination of egg-shell. The optimum calcination conditions found to produce the strongest mortar were 900°C for 12 hours. Egg-shell lime mortar had exceptionally high strength which was attributed to the negative effect of shrinking and compaction of the lime during curing.

The term "lime" comes from the word limestone. Limestone rocks were converted to lime powder by burning (calcining). The process of converting limestone to lime was an old process and it has been well documented, archaeologically. It has been established that the production of lime is the oldest industrial process can"ied out by humankind, dating back thousands of years. In fact, 3650 years ago Moses instructed the people of Israel, after they crossed the Jordan River, to set up large stones and whitewash them with lime and write the laws of God in lime. Lime was the most commonly used cementatious binder until about a century ago, when its use started to decline. It was replaced by Portland cement, a material essentially developed for structural purposes in the era of the industrial revolution. Portland cement has certain advantages over lime. The material develops strength and hardens faster for work to be carried out at a greater pace with better quality control and agreed standards. It has now become the dominant cementitious binder, part of it due to aggressive marketing of the material by the manufacturers. The use of Portland cement in the restoration and conservation of old buildings and structures in the UK over the past few years has resulted in a series of problems and cost millions of Pounds to eradicate. The decline in the use of lime in many countries has not only caused a diminution of its production, but has also contributed to a gradual disappearance of the traditional skills required both to produce a high quality product and to use it in construction. Therefore it is necessary to reintroduce and revive the old tradition of using lime by providing more information about its production and use. At present there are no comprehensive standards or code of practices, British or European to aid engineers and contractors in the use of hydraulic and non hydraulic limes in construction. BS EN 459 (2001) gives guidance on the chemical and physical properties of limes but it does not provide vital information about lime-based mortars e.g. mix proportions, mixing process, bond with masonry units, curing methods and all other necessary aspects to assess in the use of the material in construction. At present it is very easy for engineers, contractors and consultants to misuse lime mortars in new construction or in restoration and conservation of old buildings. Part of the decline in production of lime and reluctance of use in construction is due to the lack of understanding of the material properties and its performance in structures. Therefore it is necessary to examine and revive the old tradition in using lime mortars in construction and look at the new technologies used presently in the production process in order to provide the necessary background and information to aid the use of the material The present study provides a literature review, test results, discussions, conclusions and background information to set up standards in the production and use of hydraulic and non-hydraulic limes and their mortars in the construction of new buildings and the restoration and conservation of old buildings. Hydraulic and non-hydraulic limes have an excellent track record in buildings through history but their use in the UK was missed for some thirty years or more. Part of the reason for undertaking this research programme was to examine the properties of pre-packaged hydraulic limes available in the market at present. The properties of limes vary considerably dependent on the raw materials, composition and manufacturing process. The results of this study showed that there was a great variation in the properties and performance of limes and their mortars. The results also showed that the properties of lime mortar improved by adding different percentages of POliland cement. The research examined the effect of sand grading on the lime mortars compreSSIve, splitting and brick/mortar bond strength. The thesis also investigated the effects of using different casting moulds and curing methods on mortar strength. The results showed that the porosity of lime mortar was one of the reasons it was a success in the past and why it was so important nowadays to use it in the restoration and conservation of historic buildings.

The first recorded use of hydraulic lime in construction can be traced back to at least two thousand years ago. Hydraulic lime, produced through either adding pozzolanic materials or calcining clay containing limestone, unlike air lime, can set and harden under water, developing strength through initial hydration reaction and subsequent carbonation. After WWII Portland cement mortars had almost completely replaced lime based mortars in modern construction. However, through conservation and specialist construction the benefits of hydraulic lime are becoming increasingly recognised. To support wider usage of these mortars there is a need for systematic study on the mortar properties and structural performance of lime mortared masonry. This thesis presents findings from a research programme conducted to develop understanding of the mechanical properties of natural hydraulic lime (NHL) mortared brickwork. The work focussed on the flexural strength of NHL mortared brickwork. A variety of material and environmental factors, including lime grade and supplier, mix proportion, sand type and age, have been investigated. In addition the research has completed an in-depth study on the influence of brick absorption characteristics on bond development. The two methods of flexural wall panel and bond wrench testing to establish flexural strength have been compared. In addition to flexural strength, initial shear strength and compressive strength of brickwork has also been investigated. A greater understanding of NHL mortared brickwork performance has been developed through this work. Performance of the brickwork has been related to properties of constituent materials and environmental factors. Recommendations for design performance of materials have been provided.