Contributions of X-ray CT to the characterization of natural building stones and their disintegration

This paper highlights the use of the high resolution scanner at the Centre for X-ray Tomography in Ghent, Belgium (UGCT), for the 3D quantitative evaluation of the disintegration of some French natural building stones. Rocks deteriorate when they are exposed to extreme weathering factors such as a combination of water and freeze-thaw cycles or high pressure. The results of those processes can be very diverse: from element migration to crust formation to the origination of micro-cracks. Thanks to its non-destructive character, high resolution computed tomography (CT) turned out to be an excellent monitoring tool as it contributes to the characterization of the internal structure of the natural building stone. X-ray CT also provides a better insight into the micro-structural durability properties of the building stone

Testing the durability of limestone for Cathedral façade restoration

This research aimed to specify an optimum replacement stone for Truro Cathedral. A variety of petrographically and visually similar material to the original Bath stone was initially selected. The stones were subjected to three different durability tests; Sodium sulphate crystallisation and large scale testing with both accelerated and climatic freeze-thaw cyclic loading. The most suitable stone was determined as the one with the best performance characteristics overall

Evolution in the use of natural building stone in Madrid, Spain

Many types of stone have been used for construction in Madrid. In historical times, their use was determined by the proximity of the geological resources, the ease of quarrying and transportation links to the city. More recently, as transport connections and quarrying techniques have improved, quality and durability have become key determinants of building stone selection. Local flint was used intensively from the ninth to the eleventh century, when it was replaced by Redueña dolostone, used in turn until the seventeenth century. Granitic rocks from the Guadarrama Mountain Range that crop out in the northern and western area of the province increasingly began to be used in the city from the sixteenth century. Traditionally known as Berroqueña stone, this building stone was quarried in a number of areas; the primary point of supply was Zarzalejo, and from the eighteenth century the granite used was mainly quarried in the Alpedrete area. Eighteenth century advances in underground quarrying made it possible to extract a limestone (Colmenar stone) located in the southeastern part of the region. Together with Berroqueña stone, this limestone became one of Madrid's traditional building stones, and both, highly esteemed for their excellent petrophysical properties and durability, are still used today

Использование золошлаковых материалов теплоэнергетики в строительных материалах

The possible trends to improve the building-technical properties of dry ashes characteristics formed as a result of solid fuel combustion at thermal power stations are presented. The results of different fly-ash conditioning technologies application to widen the trends and to increase the volumes of their use in the construction materials and products.Представлены возможные направления улучшения строительно-технических характеристик сухих зол, образующихся при сжигании твердого топлива на тепловых электростанциях. Приведены результаты применения различных технологий кондиционирования свойств золы для расширения направлений и увеличения объемов их использования при производстве строительных материалов и изделий

The Soft Side of Stone: Notes for a Phenomenology of Stone

Stone represents the firmness and intransigence of the world within which we live and act. But beyond the perception and appropriations of stone, diverse meanings lie hidden between the hardness of stone and its uses. At the same time meaning must be grounded in the stabilizing presence of a common world. Yet if all that can be said is not about stone simpliciter but only an aesthetics of its perception, uses, and meanings, have we not gained the whole world but lost its reality? The underlying issue is therefore not aesthetic but ontological

Strategies for building pathology reports in an urban rehabilitation process: Project of the Old City Centre of Coimbra

The increasing interest on architectural heritage associated to the recognised building value, at economic, social and cultural levels have stimulated, in the recent decades, the urban rehabilitation and renovation o several cities in Europe. Despite the strategy or method adopted in a city renovation process, its efficiency depends mainly on: type of buildings (structural systems, construction techniques and materials); intervention level (singular buildings, groups of buildings, urban zones, etc.); and, project objective (risk assessment, decision making to support future rehabilitation projects, definition of council maintenance policies, etc.). In what concerns large renovation programs of old city centres, choosing the most adequate approach for inspection, appraisal and diagnosis is a complex task that can determine the success or failure of the project purpose. This paper describes the preparation phase of the inspection of 700 buildings located in the old city centre of Coimbra (Portugal), where a global renovation process is planned for the forthcoming years. In the scope of the renovation and rehabilitation process, the city council contract a complete identification and inspection survey of the buildings, directed on three different domains: (a) architectural typologies, (b) constructive and pathological condition of buildings, and (c) socio-demographic characterisation, of this part of the city. It will be present the check-lists developed and some of the obtained results on point (b), related to roofing systems, and exterior façades. This diagnosis procedure shows that the inspection results quality is quite dependent on the items surveyed for each construction element (roof, façade, internal members, installation efficiency), as well as on the possibility of their correlation for a single building. The adopted method has been applied on 70% of the buildings inspected within the project perimeter. Further treatment of the inspection and appraisal data will allow the developing pathology reports and list repair actions, and estimating rehabilitation costs. It will also help to produce defect level diagrams and seismic building risk maps, but, most important, to improve and guide a renewal strategy and intervention methodology for old buildings

The complex binder based on Portland cement andash-and-slag wastes from thermal power stations

Increase in the balance of boiler and furnace fuel of the energy sector of the Republic of Belarus the proportion of own energy resources (milling peat and wood chips) places priority on resolving the issues of utilization of ash-and-slag wastes and reducing the area of ash-and-slag disposal sites, which cause irreparable damage to the environment. A considerable amount of research has been devoted to the utilization of ash-and-slag wastes. There are more than 300 technologies of their recycling and use. Ash and slag wastes are used in the production of concrete, mortars, ceramics, heat and water insulating materials, road construction. The world experience shows the potential of 70-80% utilization of ash and slag, as, for example, in some European countries. However, the cost of the recycling of ash-and-slag wastes with the production and simultaneous neutralization of wastes can be higher than the cost of the production. One of the directions of the use of ash and slag wastes is the production on their basis of new types of complex binder that have increased strength and low prime cost. The replacement of a part of cement with active mineral additive allows to achieve significant saving of binder. The existing methods of the production of complex binders include the stages of joint or separate grinding of cement clinker and mineral additive with following mixing. Significant energy costs for grinding increase the cost of binder. In this regard, the development of the effective complex binder with the use of ash-and-slag wastes of the Belarussian state district power station in Orekhovsk using resource-saving technology is the actual research objective