STONES -materials of sustainability

Post 676 –by Gautam Shah

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SindhuDurg Fort

Stones are procured through collection off the surfaces, by extraction (mining) from depths of the earth and reused (spolia) from existing or demolished buildings. The stones of these types are abundantly available. Major problems with sustainable stone exploration are the economics of transportation. Other issues are cost of size conversion, surface preparation and quality equalization. In future greater attention will have to be for management of stone-wastes at locations of mining and processing.

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Stones are used for their surface quality and structural properties. And in spite of technologically greater capacity to search over wider and deeper terrains, stones always remain scarce or unviable at many places. At use-points natural stones must arrive in optimum mass-units and in forms that are viable for transport, storage and usage.

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Stone resources are of basic two types: Surface Stones and Extracted Stones.

Surface Stones show many, but qualitative and size variations. Over a geographic region, though the quality is fairly consistent. Quality equalization can only be enforced through region-based sourcing, selection and separation. Surface-collected materials are naturally formed (boulders, pebbles, gravel, sands, etc.) or wastes of stone processing. Such materials are fractured along the plane of shearing force or across the weakest plane, and so show varied structural properties, colour and grain structure (texture) on different faces. These stones are equally weathered on all faces.

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Extracted Stones materials are loaded (buried) with varying depths of overburden, of the same or different nature of materials. The over burdening mass, protects as well as contaminates the stones. The water passing through the organic soil burden is nominally acidic, and so affects the alkaline stone mass. Fresh lime stones are soft and porous, but when exposed to Carbon dioxide begin to change, harden due to the aeration.

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Typically, igneous (granite, trap) and metamorphic rocks (marble, schist, slate) have nearly crystalline compounds, and are not stratified so do not present any layers or strata. Sedimentary rocks (lime stone, sand stone, soap stone, travertine) are formed of uniform constitution, though stratified, often in inclined and curved formations due to movements in the earth mass. Sedimentary rocks show grains intervened by a cementing medium.

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All stones collected from the surface or mined, must go through some primary processing.

■ Subtractive processes remove excess mass for surface cleaning, sizing, cleaving and pattern sculpting. The processes are, chipping, splitting, cutting, dressing, sculpting, engraving, grinding, polishing etc.

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■ Formative processes do not add any mass but change the spatial or physical characteristics of stone such as its sensorial, structural and environmental behaviour. The treatments include impregnation, edge reinforcing, various types of chemical treatments through acid, alkali, solvent and other oxidative compounds, heat and flame treatments, sintering, spluttering, dying, bleaching etc.

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■ Additive processes add to the stone mass. Till very recently technologies involved were of Surface layering by way of coating or cladding. But now ceramic formation, metal alloying and deposition, surface synthesis, surface molecular treatments are being used.

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The sustainability of stone is dependent on basic three aspects: 1 Minimum mass for largest possible surface extent, 2 Reuse of all waste products, 3 New uses for very small sized materials (sand, gravel, pebbles).

1 Stones are valued for their surface qualities, and we need to extend the Surface area. The extended surface reduces the mass / weight of the stone. This can be done by thin sectioning, and by techniques of amalgamation of bits and pieces.

2 Stones have certain structural properties which we can be altered and reinforced. This process starts with new ways of excavation, extraction and conversion of the material. And can be extended to new forms of usage.

3 A new field is emerging on materials’ technology front. This is about creating new materials combinative formations. The formations include various types of composites, geometrical or spatial compositions and combining or ‘synthesizing’ materials of diverse nature. These reconstructive processes include using particulate matter (various grades of fineness such as dust, sands, gravels, pebbles, chips and lumps) as fillers with a matrix of resin or cement. Forming layered composites with sheets or slabs of stone and other materials (polymer sheets, fabrics). Forming amalgamated materials by lamination, co-extrusion, sheet forming, metalizing, ceramic forming, etc. and chemically converting stones into byproducts like minerals and chemicals.

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Spolia (Latin, ‘spoils’) are repurposed- recycled building stone used for new construction, or decorative sculpture reused in new monuments. These stones are from existing or demolished buildings or building workshops.

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Sustainable Strategies for Stone

Stone is the least of bio-degrading materials, so not a ‘recoverable or ecological’ material. It can be recycled through reuse processes. Sized blocks of stones for masonry and flooring, have been reused since Egyptian and Roman times. But stone-waste dumps at mine heads and workshops are causing environmental problems.

 

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Stones are broken or crushed from larger stocks for many purposes like roads, embankments etc. which is an avoidable practice. Stones like gravel and boulders (from river beds and old glaciers’ paths) are some of the toughest stones, left over after natures’ processes. But these rounded stones are not used in masonry work, or broken down to smaller sizes. River and seacoast sands are becoming scarce in supply, and could easily be replaced with ground stone, at least in mass concrete plants.

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REUSE of BUILDINGS

Post 645 –by Gautam Shah

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Buildings continue to be relevant for many different reasons. Buildings persist, primarily by changing the functions they serve, secondly by redefining the form, and in rare cases, by altering the surroundings. Buildings are continued by Enabling interventions and Restorative actions. Re-use is a process of re-endowing value to neglected built-forms, which otherwise could see demotion.

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Turbine Hall of Bank side Power House Wikipedia image by Cwrcun

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Tate Hall (original turbine machine room)

A building and its lands, both are precious assets. Buildings are acquired at a great expense of resources, effort and time whereas the lands, now have new relevance being in central location and good connections. No one wants, either to go wastes. Buildings and the lands must be put to different use. Reuse strategies relate to establishing the lands and building for a ‘purpose other than the original one.

Location is the external realm of the building. It has two facets: the distance or the extent and the stack holders of the building. A building serves certain terrain or physical distance. When these get enlarged due to efficient transport services the usage is increased, but conversely barriers like railway tracks, canals, closure of roads, or loss of visual identity affects the raison d’ etre (reason for existence) of the building. Stack holders become insincere for maintenance when the location begins to deteriorate due to economic, social or political problems, and affects the pride or faith in the building.

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Batter sea Power House Station Building being  redeveloped with specific conditions like preservation of four chimney structures > Wikipedia image by > Attribution Nigel Cox

Lands become available for reuse, due to the changes in land zone and occupation patterns, such as residential to commercial or industrial to residential. Lands need re-validation of purpose when new developments like location of an airport, highways, railway tracks, etc. take place in neighbourhoods. Existing lands have an advantage of location and connections.

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Arnold Print Works as seen from Marshall street in North Adams, Massachusetts> Wikipedia image by Beyond My Ken

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Main Entrance Massachusetts Museum of Contemporary Art (MassMoCA) Wikipedia image by Beyond My Ken

Reuse of lands and built spaces is a form of urban rejuvenation, rationalization of urban density and strategy for sustainable use of resources. Reuse, sometimes deals with issues of conservation and so considered by some, as ‘compromise between historic preservation and demolition’.

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One of the Reuse project by Gasometer City, Vienna, Austria. Four disused gasometers were revamped into residential quarters > Wikipedia image by (Andreas Poeschek by CC-BY-SA-2.0-at)

Gasometer A in Vienna, www.wiener-gasometer.at

Internal Courtyard of Gasometer at Vienna > Wikipedia Image by Andreas.poeschek by CC-BY-SA-2,0-at

To use a building for a different purpose, many corrective actions are required. Redefining the form of a building is difficult as it is expected to satisfy, simultaneously, the functional needs and the value system in the society. In the first instance if the owner finds the corrective actions uneconomic, would rather opt for a new entity. In the later case, the changes in the form may make the society apathetic to the building’s revised ‘look’. Often, the cost of renovation, rehabilitation or restorations, are more costly than demolition or building newly.

The preservation of surroundings of buildings requires social, political and financial involvement, which are beyond the reach of the owner or user. It is only for buildings intensively serving social functions or buildings with historical connections that surroundings will be conserved or even redefined. A building, if is a public utility or society’s pride and prestige, its surroundings will be maintained or even resurrected. Changes in the surroundings force functional changes in the building, however, whether one makes the changes to be with surroundings or resists, both ways the building gets altered.

Old buildings become unsuitable for their conceived requirements with passage of time. The building’s own technological validity (of service systems’ and components’), and the circumstantial relevance of the planned usage, both, change, and independently. To these, political conditions and financial consideration (benefit accruing out of it) complicate the assessment.

A building, if it has a form of architectural styling then it is continued as a relic. When it has commemorative connections, in appreciation of its past, the building becomes a monument. Buildings that need to be remembered are restored or preserved to retain their form, but often in complete absence of the original setting. A building that has substantially lost the form and has indistinct connections can be enacted through re-imaging of its setting, like through Sound & light (son et Lumiere) shows on historical sites.

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Reused Pillars for Arcade at Adhai Din Ka Zonpada India > Wikipedia image by Billyakhtar

A building as a built-form stays till the structure or parts of it can provide shelter. And even after the loss of its integrity as a shell for shelter, its parts and components are scavenged for reuse. Romans and many others have used refuse in their new constructions. There are unknown costs in managing debris of old buildings, related to handling materials like glass wool, asbestos, and radio active contaminants, and demolition and removal of materials from dense localities.

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Asbestos and Lead paints require specific care for removal

Older buildings need substantial review of their functions, due to changes in ownership, reassessment of efficiency, styling and context. As the buildings age, the nominal surface related changes go deeper into the body of structure. Such changes are not easily perceptible, and can grow to very dangerous level. This is a stage when original design documents are not available. The new technology components and systems may not match the existing provisions. Repairs and maintenance schedules can restore parts, components and systems, provided the design is ‘open-ended’. However, holistic creations or ‘close-ended’ entities deteriorate completely without any scope for corrective measures.

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STONES -Opportunities of Intervention

Post 329 –by Gautam Shah 

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Stones have naturally variegated constitution and surfaces. These, provide with inexhaustible opportunities to work to many different forms, sizes, and finishes. The qualitative consistency of man-made materials though, poses a great challenge to multifarious nature of stone materials.

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The Opportunities of Intervention for stones are of following types:

  1. Stones alone
  2. Stones with other earth-based materials
  3. Stones with natural organic materials: such as plants
  4. Stones with man-made materials such as Ceramics, Metals, Polymers (plastics and elastomers)

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1 STONES ALONE

Stones represent, one of the largest resource of earth-based materials. We have not touched even a small fraction of its top layer of mass. Ecologically its use or disposals are manageable. Only problems with stones supply are its inconsistency of sensorial and other surface qualities, and difficult to predict structural properties. This is where man-made materials prove to be superior and reliable. Man-made materials require complex and costly processing whereas stones as a natural resource though unlimited in supplies have high costs of extraction and transportation. Man-made materials are highly custom created and so are not reused extensively, but stones have nine lives and can be used till conversion to form of a dust particle. Man-made materials are produced through multiple-processing, making them difficult to recycle or dispose off safely.

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2 STONES WITH OTHER EARTH-BASED MATERIALS

Stones combined with other earth-based materials provide many opportunities of usage. However, stones by themselves or with other earth-based materials have limited scope for combinations. These are mainly by positioning such as spreading, layering or stacking with gravity, by using electromagnetic forces or by kinetic method of tying-knotting. Few earth-based cementing materials such as mud, pozolana or plant gums are insufficient in supplies and technically inadequate. Yet use of natural materials with very small proportion of man-made of joining materials and technologies can achieve outstanding results.

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3 STONES WITH NATURAL ORGANIC MATERIALS

Use of organic materials such as plant-based resources (Jungle, Farm produce) has not been explored adequately. Primitive man started using wood in combination of stone, which has been extended to buildings. Its use is limited, as wood is a scarce resource (not easy to replenish). Other organic products require several levels of processing before qualifying their application with stones. Every single new application is worth its wait and expense.

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4 STONES WITH MAN-MADE MATERIALS

Stones have been used with man-made materials like metals etc. But most technologies involve non-mixing combinations, such as mechanical joining, adhesion fixing or coating. Stones and earth-based materials have been used in many synthesizing processes. Stones in their physical form and characteristics have been exploited, as fillers, for creation of composites. However, stones have been less frequently synthesized with man-made materials such as ceramics, metals and polymers. These are going to be the opportunities for the next generation.

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The inspiration derives from the successes achieved in combining Ceramics with Metals. Ceramics and metals individually have diverse temperature of forming. At a temperature a ceramic begins to evolve some metal either evaporate, liquidize or form oxides. A combination seemingly impossible is now being achieved, for example in electrical transmission equipments, electronic components, tools and cutting edges making. Similarly stones can be combined with many other materials.

Metal application technologies provide exciting results here. Metalizing a stone surface with metallic particulate or molecules, by plating and sputtering techniques is not farfetched. Synthetics are mainly made with organic (carbon-based) monomers in polymers but chaining. These have been used both as the matrix and fillers components in composites. And can we visualize stones, not in the role of filler, but of a matrix in composite forming.

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