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CAUSES OF DECAY

CAUSES OF DECAY. ST GEORGE OF THE GREEKS CHURCH IN FAMAGUSTA. What may be the causes of decay specific to the building?. Understand the building by considering its Design Construction technique Materials Location Period of construction.

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CAUSES OF DECAY

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  1. CAUSES OF DECAY

  2. ST GEORGE OF THE GREEKS CHURCH IN FAMAGUSTA What may be the causes of decay specific to the building? • Understand the building by considering its • Design • Construction technique • Materials • Location • Period of construction

  3. THE SYSTEMATIC APPROACH FOR THE DIAGNOSIS OF A BUILDING DEFECT 1.Problem Definition 2.Field Survey and Inspection a.Visual Inspection, includes: Taken Photos Looking for similar defect in the same area b.Field Measurement, includes: • Written record about the sizes and dimensions of the defect • Samples of the defected material and its adjacent area are taken

  4. The primary source and causes of deterioration and decay in structures and buildings can be listed as follows: 1.Human 8. Faulty Construction 2.Chemical 9. Faulty Materials 3. Atmospheric 10. Faulty System 4.Structural 11. Ground/Soil Properties 5. Moisture 12. Improper restorations 6.Fire 13. Vandalism 7.Faulty Design

  5. Effects of war: Canon balls hit the outer walls during Ottoman siegeLack of maintenance after the siege.

  6. The building was designed adjacent to a smaller church (St Symeon),which has effects in the structural problems.

  7. Lack of butresses (design and construction fault) Proximity to the sea rising dampness Ground properties structural deformations Material properties Local Sand Stone which is porous Climatic conditions Biological growth (Vegetation)

  8. STRUCTURAL • Reaction of the structural elements to settlement, moisture, shrinkage and thermal movements. • Reaction of the structural elements to the change of loading patterns. • Natural aging of the structural elements • Reaction to the corrosive elements in the atmosphere • Deterioration due to inadequate inspecting and maintenance

  9. Structural Craks Traditionally built structures have emerged as aresult of trial-and-error. Compared to modern buildings, very few structural calculations were involved in their construction. The great majority of cracks tend to be superficial and benign so it is necessary to understand the properties of cracks, and why they have happened.

  10. Leaning Tower of Pisa

  11. Rising Dampness • What is rising damp? Rising damp occurs as a result of capillary suction of moisture from theground into porous masonry building materials such as stone, brick,earth and mortar. The moisture evaporates from either face of the wall(inside or outside), allowing more to be drawn from below. The height towhich the moisture will rise is determined by the evaporation rate andthe nature of the wall. The normal limit for rising damp ranges from 0.5to 1.5 metres above ground level.

  12. Soluble Salts • The damaging effects of soluble salts are intimately linked with wetting and drying cycles at the masonry face. Almost all historic building materials are porous to some degree. The network of pores in stone and brick contain water in which varying quantities and types of salts may be dissolved. • As drying/evaporation occurs at the masonry face salts crystallise out of solution producing the white crystals known as efflorescence.

  13. Efflorescence 1. a change on the surface to a powdery substance upon exposure to air, as a crystalline substance through loss of water. 2. to become incrusted or covered with crystals of salt or the like through evaporation or chemical change.

  14. Efflorescenceis a fine, white, powderydeposit of water-soluble salts left on the surface of masonry as the water evaporates. • Efflorescence is normally the white, powdery scum that can appear on masonry walls after construction but can also be brown green or yellow, depending on the type of salts.

  15. Development of efflorescence salts on the highpermeability mortar wall . Microstructure of the deposited salts by scanning electronmicroscopy.

  16. Biological Growth (Vegetation) • Historic buildings and monuments are liable to be affected by a wide variety of 'biological growth' ranging from the roots of mature trees that form part of a designed or natural landscape to micro-organisms that can be found on external and internal surfaces of building materials.

  17. TREES AND SHRUBS Damage may be caused by trees and larger shrubs in various ways including: -root action on walls, foundations, pavings, monuments and below-ground drains; -trunk and branch contact with walls and roofs; -blockage of rainwater disposal systems by leaf fall; -shading of surfaces. 

  18. IVY AND CREEPERS • This genus of evergreenclimbers prefers well-drained, alkaline soils, and species such as common English ivy are commonly found on buildings and monuments. • Aerial roots and woody growth can penetrate open joints causing displacement of bricks or stones, while with broken walling there is risk of the facing material being forced from the backing or core.

  19. LICHENS • Lichens are a symbiotic association of photosynthetic micro-organisms held in a mass of fungal hyphae. • The hyphae retain moisture and minerals, and the fungi display acids that aid the uptake of minerals.

  20. MOSSES • Mosses are an example of a non-vascular plant , which, unlike larger plants, do not have vascular tissue to transport water and nutrients. • Mosses are typically green and photosynthetic when young, turning brown or red-brown when ready to release spores.  growing on a boundary wall together with lichens and mosses 

  21. Their presence on porous materials such as roofing tiles canresult in frost-related damage and large growths can restrict moisture evaporation.Deposition of mosses may also block rainwater disposal systems.

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