damage atlas historical cuenca

S. De Jongh – M. Van Wijnendaele – F. Cardoso – K. Van Balen samat

Damage Atlas of historical Cuenca, Ecuador samat

Damage patterns found in (mainly earthen) building materials samat

Katholieke Universiteit Leuven, Belgium :: Universidad de Cuenca, Ecuador :: VLIR‐IUOS :: 2009

Contents 1. Introduction ..................................................................................................................................... 1

2. How to use the Atlas in 3 steps ....................................................................................................... 2

3. Cuenca’s cultural awareness, environment and climate ................................................................ 3

4. Material and its value, damaging cause and damage pattern ........................................................ 4

I. Classification ........................................................................................................................................ 5

1. Classification through material type [Which material is affected?] ................................................ 5

2. Classification through damaging mechanism [What is the cause?] ................................................ 7

3. Classification through damaging pattern [What do you see?] ........................................................ 9

4. Classification through building state [What is the actual state?] ................................................. 12

5. Classification through severity [How bad or threatening is the damage?] ................................... 12

II. Case Studies ....................................................................................................................................... 14

1. Aesthetical and surface problems ................................................................................................. 14

2. Disintergration (surface to structural problems) .......................................................................... 28

3. Surface cracks ................................................................................................................................ 50

4. Structural cracks ............................................................................................................................ 52

5. Other structural problems ............................................................................................................. 64

Damage�atlas�of�historical�Cuenca,�Ecuador�(earthen�materials)��

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1. Introduction��This�Damage�Atlas�wants�to�be�a�helpful�tool�in�defining�damages�and�their�causes�in�historical�building�materials.�Research�methods�and�solutions�for�occurring�problems�are�integrated�as�well.�More�specific,�the� center�of� this� book�are� the�materials� and�buildings� in� the�Unesco�World�Heritage� city�of�Cuenca�(Ecuador).�

A�manual�will�lead�the�reader�through�this�atlas�which�should�be�used�preferably�in�situ�and�in�an�active�way.�The�first�questions�always�should�be�"What�do�we�see?"�and�"What�are�we�talking�about?"�since�a�proper�investigation�and�correct�description�are�necessary.�In�a�second�stage,�"What�are�the�(physical)�damaging� causes?"� and� "What� is� a� sustainable� precaution� or� solution?"� are� critical� in� evaluating� the�seriousness�and�developing�right�decisions�for�damages.��

SaMat� is� the� Systematical� Analysis� of� these� Materials� and� Their� damages� through� centralizing� and�validating�data�on�an�engineering�level.�SaMat�comprises�the�methodology,�the�database,�called�SaMat�Doccenter1,�and�this�damage�atlas�as�resulting�product.�This�master�piece�should�lead�to�our�thesis2�in�partial�fulfillment�of�the�requirements�for�the�degree�Master�of�Applied�Sciences�and�Engineering�(Civil�Engineering).� The� thesis� fits� within� the� VLIR�IUOS� project� "World� Heritage� City� Preservation� and�Management"3.�

We� have� to� thank� all� the� people� who� were� involved� and� extremely� helpful� for� this� project.� Special�thanks�go�to�prof.�Koenraad�Van�Balen,�prof.�Fausto�Cardoso,�arq.�Veronica�Heras�and�our�families.�

Sam�De�Jongh�and�Matthias�Van�Wijnendaele�

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Cover�(left�to�right,�top�to�bottom):�Casa�de�Los�Arcos,�Casa�de�Las�Posadas,�Iglesia�Santo�Domingo�and�Casa�de�las�Palomas,�carrying�adobes,�adobe�wall�

There�are�some�copylefts�to�the�authors�on�photos�in�this�book�

��1�SaMat�Doccenter�is�available�online�https://ernie.urania.be/oberon/mvwn/Thesis/doccenterV6/�or�on�the�included�CD�and�is�only�usable�with�Internet�Explorer�(all�versions)�2�2009,�“Earthquakes�and�other�damaging�mechanisms�to�earth�structures�(case�study�Cuenca,�Ecuador)”�3�Information�on�the�project�can�be�found�on�http://vlir�iuc.ucuenca.edu.ec/proyectos_detalle.php?proyecto=20�

Damage atlas of historical Cuenca, Ecuador (earthen materials)

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2. How to use the Atlas in 3 steps This book is intended for students and professionals (architects, engineers…) involved in (problems with) historical buildings in Cuenca. This book is a guide in determining damaging causes and proper solutions but can’t replace the expert.

Part I of the book comprises definitions, explanations and classifications, while part II (in color) includes the different case studies.

Step 1 ‐ First, the observed damage has to be classified with the help of the figures in the cases (part II of the Atlas). The respective definition of the damage type with the probable causes of the damage can be found in part I. Step 2 ‐ Afterwards, the user’s own hypothesis and further analysis can be compared with the first idea which can be adjusted if needed. Through facts‐analysis and visual inspection, first assumptions can be made and should be verified or rejected by further laboratory and literature research. Step 3 ‐ In a third stage the opinion and help of an expert or the experience and knowledge of local people can be important since a wrong analysis and treatment can cause further harm to the building.

Special care should be taken at all times in separating damage and cause clearly from each other.

All data gathered during our expedition to Cuenca can be found in the Doccenter database on the CD attached to this Atlas. This database comprises photographs from us and other people, all investigated buildings and damages. Also papers and presentations and references can be found here. This Atlas refers to Doccenter with following symbols

Referring to buildingID (building identity number)

Referring to photoID (photo identity number)

Referring to damageID (damage identity number)


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3. Cuenca’s cultural awareness, environment and climate The historical importance of the city center of Cuenca is big and UNESCO approved this in 1999 by declaring it as a cultural World Heritage site. The awareness of the local people and governments is rising but still on a low level. Academic staff, historians and architects are playing a leading role in the conservation of the historical city. The existing VLIR‐IUOS project is an example of this concern.

Cuenca is lying in a dale of 4 rivers in the high mountains of the Andes at 2500 m above sea level. The environment is healthy, but due to heavy traffic combined with unrefined oil, local air pollution is a great threat for the city.

At this height, the climate is not comparable with the tropical weather of the rainforest and coastal region (e.g. Guayaquil). In contrary, Cuenca has a year‐round mild climate with an average daily temperature of 16°C. The temperature is not varying much during the year with maxima and minima of around 20°C and 10°C respectively (see Figure 1Error! Reference source not found.). It is comparable to the spring season in Belgium. There are no temperatures lower than 0° measured in this period. The rainy season with periodic afternoon showers, generally lasts from mid‐October until early May. A maximum of 110 mm monthly rain fall is found in April and May, proving the local saying “Avril, aguas mil”4. The relative humidity is less than 80 % (comparable to spring and summer in Belgium). Data from ISMCS v4.0, NOAA National Data Centers (US Department of Commerce) for Cuenca and from Royal Meteorological Institute (KMI) for Belgium were used.

Since the earth is moving around the sun in a quasi‐circle with a 23°27’ inclination, seasons exist. In Ecuador however, there is no actual north (where the sun never comes) or no south as we know it. Only between 23rd of September and 21st of March, the sun is standing in the South. This should be taken into account for damages caused by the sun (e.g. algae growth). The sun rises and sets in the East and West, but its path has only a little variation to the South or North during the year. This explains the stable climate through the year.

Figure 1: Climate data for Cuenca (source: ISMCS v 4.0, NOAA National Data Centers) and Belgium (source: KMI)

4 “Avril, aguas mil”, dixit José‐David Heras Barros meaning “A thousand rain showers in April”

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Mon

thly Tem

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Highest Temperature (Cuenca, 7‐year Average)

Highest Temperature (Belgium)

Lowest Temperature (Cuenca, 7‐year Average)

Lowest Temperature (Belgium)

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Precipitation (Cuenca, 10‐year Average)

Precipitation (Belgium)

Relative humidity (Cuenca, 10‐year Average)

Relative Humidity (Belgium)


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4. Material and its value, damaging cause and damage pattern What is damage or deterioration? It’s the reduction of ability to perform up to an anticipated defined standard due to an unwanted change of any property other than considered normal. This process of change causes a damage pattern which is determined by the severity of the damaging agent and the resistance of the material to the damaging mechanism. When this mechanism is more severe than the material’s resistance and the damage reaction is higher than accepted, one speaks from damage (Franke & Schumann, 1998).

On the other side, not all changes are unwanted (e.g. renovation) and some changes can be considered as normal (e.g. renewing outdoor paint). In this last case, weathering or erosion has found place due to the action of weather and environment which is completely predictable.

Also some damage can be considered faster as damage when the building (or object) is more valuable. As engineering students, we are not participating in the estimation of the (historical) value of buildings. However, we are influenced by the enthusiasm of the Cuencanian historians and architects, learning the importance of colonial earthen dwellings.

The key issue on studying damages is to distinguish damaging patterns from their (primary or secondary) causes. For example, powdering of bricks is the damaging pattern due to a chemical process introduced by urine (secondary cause). The primary cause is the biological deposit of human urine (see Figure 2).

Figure 2: Building materials are affected by damaging mechanisms resulting in a damage pattern

Material [3] Damaging mechanism [5]

Damage pattern [6]


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I. Classification 1. Classification through material type [Which material is affected?]

Different types of material are used in the historical buildings of Cuenca. Next to cloth (for ceilings), paint and glass, this section gives a summation of the most important ones.

Stone (piedra) and marble (mármol) – During the colonial period Pumapungo was declared a public quarry providing stone for the foundations of colonial churches and houses. Also the 4 rivers were a reference for round stones (piedra del rio). On the other hand the historical buildings in Cuenca are a reference for honey‐coloured and pink travertine marble from the Sayausì mines (e.g. actual city hall or Alcaldìa, 13). In Ingapirca ( 211) diorite stone (intrusive volcanic stone) was found. This stone is characterized by its visible crystals (> 1mm). But also the finer variant andesite stone (extrusive volcanic stone) is present in and around Cuenca with crystals invisible for the eye. Other volcanic stones are from the pyroclastic, tuff or ashstone type containing bigger fragments ( 217).

Wood (madera) – Eucalyptus wood is used as such in roofs, floors or as supporting element in composite walls (see bahareque). The type, known as Eucalyptus globules, was introduced from Australia in the 1860s and dominates the landscape of the inter‐Andean valleys (Neill, 2008). It is a hardwood that earns high marks for strength, durability and excellent weathering characteristics similar to those of teak wood. Hardwoods have pores or vessel elements that occur among fiber and parenchyma cells. Cellulose content ranges from 40 to 50% with 15‐25% lignin (less than softwood) and 15‐25% hemicelluloses (more than softwood). The remaining components consist of various extracellular compounds (Blanchette, 2000).

Reed (carrizo) – The reed in Cuenca is found to be sugar cane (Saccharum officinarum) and is locally called carrizo or sometimes caña (de azucar). They also can make rope or strings with cut and dried leaves. In Ecuador also the flatter caña guadua and used in construction in the coastal part and the Oriente. Do not confuse carrizo with the giant cane or bamboo reed Arundo donax (in Ecuador called carrizo grande or caña brava from which the popular caña drink is made.

Earth (barro) – Earth can be found on the construction site or at local extraction sites. Generally very little is known about the characteristics of the mud. The properties for different locations near Cuenca are investigated (De Jongh & Van Wijnendaele, 2009). Earth is used in adobe, tapial and bahareque, as well as in finishing layers and in mortars for cementation of tiles, stones and (adobe) bricks.

(Polychrome) metal sheets (placas de latón policromado) – Multicoloured sheets of zinc are found a lot in interior (mainly ceilings) as well as in exterior decoration (Casa de los Arcos, 214). The history of this from Europe imported sheets is found in the nationwide boom in exports around 1860 (Torres Hidalgo, 2007).

Wrought iron (hierro forjado) – This iron has a very low carbon content and due to slag inclusions it is fibrous. It is ductile (not brittle) and easily welded. The material was introduced during the 1860 boom (Torres Hidalgo, 2007).


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Fired bricks (ladrillo) – A ceramic material obtained by preparation, moulding (or extrusion) of raw material (clay) and subsequent drying and firing at an appropriate temperature (Franke & Schumann, 1998). It is widely used as building material in new constructions in the new district of Cuenca (El Ejido).

Roof tiles (teja) – This ceramic material consists mainly of clay but it is not known with the usual glaze finish. There shape is semi‐cylindrical (called mission or barrel, 207) or flat ( 59).

Trash of tiles (cisco) – Cisco is found and used as protecting layer on bahareque and adobe masonry ( 267). Broken tiles are applied in the earthen surface layer (revoque).

Reinforced concrete (hormigón / concreto armado) – A construction material composed of cement, gravel, sand and water which hardens after a chemical process called hydration. It is mostly reinforced with steel to increase the tensile strength. It is a modern building material used in Cuenca (Universidad de Cuenca, 260). A decorative concrete floor, called terrazzo was found in iglesia Santo Domingo ( 59 and 379) as well.

Adobe masonry (mamposteria de adobe) – Adobe walls should not be mistaken for tapial or bahareque even if they are called so in literature (e.g. Guía de arquitectura). Adobe bricks are made of earth (containing sand and high amounts of clay), water, straw and sometimes animal excrements. They are made in wooden moulds with dimensions of 25‐60cm by 14‐20cm by 10‐17cm. They can be reinforced with steel in combination with cement mortar, but in Cuenca only unreinforced adobe is found (see Figure 3a). Additives such as asphalt, ethyl silicate and other chemical additives are also not used. Its composition (clay content, type of clay, particle size distribution, soluble salt content…) is determinant for the adobe properties (colour, compressive strength, durability…) and is investigated by the authors in their thesis. Finally, the properties of an adobe brick cannot be plainly extrapolated to the masonry, a combination of earthen joints, wooden reinforcement and adobe bricks.

Rammed earth (tapial) – Although it is not much found in Cuenca, rammed earth is a traditional way for construction of walls (see Figure 2b). Moist earth is poured into a formwork (encofrado, two connected parallel plates) in layers of to 15 cm thick, and then compacted by ramming. Since it is monolithic, a longer life is granted in comparison with adobe (Minke 2006).

Figure 3: (a) An unfinished adobe wall in Cuenca (SaMat Doccenter 206); (b) Shrinkage cracks and production joints of tapial in Ecuador (Minke 2006) (c) A rural house made of bahareque (SaMat Doccenter 322)

Wattle‐and‐daub (bahareque) – In the wide surroundings of Cuenca, bahareque is made of wood, reed and earth and is known as bahareque de tierra (see Figure 3c). The primary (diagonal V‐structure or crossed) and secondary (vertical parallels heart‐to‐heart 40 cm) structures are always made of wood. Regularity in this framework is rare since windows and doors are introduced in the structure. The reed is braided on both sides of this structure. Since the cavity between the reed is not filled we are dealing


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with hollow bahareque (tierra hueco). Afterwards a thick earthen layer (revoque) with straw and a thin earth‐chalk layer (empaneite) are applied (Ortiz Crespo, 2005).

Lime plaster (empaneite, yeso) – Although earthen surface finishes are found as well, a lot of (adobe and brick) buildings are finished with lime plasters. Lime plasters are a mixture of calcium hydroxide and sand.

Cement plaster (cemento) – Cement is regularly used as surface layer and is a mixture of (plaster,) sand, Portland cement and water. The choice is (often incorrectly) based on its high strength and water resistant properties.

For an overview of how and where these materials are used in the historical buildings of Cuenca, the authors are referring to their thesis. Patios and balconies (decorated with wrought iron) with a wooden structure, ceilings of wood or zinc are typical. A traditional colonial dwelling may consist of river stones at the basement, adobe masonry on the ground floor (paved with floor tiles or small river stones) and bahareque for the upper floors (with wooden floors). Tiles on the roof and cisco at the side walls makes it complete. But also brick masonry is frequently found. Sometimes they are left naked, but often they are finished with travertine marble or – more common – decorative plasters.

2. Classification through damaging mechanism [What is the cause?] We can also classify the damages by its cause or damaging mechanism (see Table 1). This gives a structural overview of the probable risks for the historical buildings in Cuenca. The damages are always listed per cause from structural (e.g. collapse) to aesthetical (e.g. staining). We should mention that some damages only can be caused in one time (an impact) and other by a continuous action (erosion). It is also important to understand the place of a damage pattern in the buildings life cycle starting from the design (e.g. general error/risk) to the end (e.g. no intervention).


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Table 1: Classification by damaging mechanisms (or causes)

CAUSE SPECIFIC CAUSE DAMAGE PATTERN Mechanical (Over)loading

Settlement Wind Use Impact Traffic Seismic

Deformation, crack, spalling Leaning, deformation, crack Leaning, erosion, pitting Crack, corrasion, polishing Chipping, crack, cut Crack Collapse, crack, loss of material

Design Renovation (/reparation) Design Construction Maintenance

Destruction (+ new), loss of material, change of impression General error/risk, structural instability, crack, choices Applied material, technique or system Incorrect use, incorrect / no intervention

Physical Water Salt (Differential) expansion

Bending, erosion, (network) crack, powdering, sanding, bulging, loss of bond, peeling, blistering, fading, staining, soiling, rotting, softening (network) crack, powdering, crumbling, encrustation, scaling, spalling, delamination, exfoliation, (crypto)efflorescence, patina, blistering, patina Crack

Chemical Metal corrosion Sun (UV) Fire Air (pollution) Water, gases, acid Graffiti Soot

Conversion, crack, loss of bond, staining Fading Destruction, crack, spalling, blackening Soiling Crack, conversion, staining Staining Soiling

Biological People and animals Beetles Moulds Algae Lichens, liverwort, Fern Higher plants Moss

Conversion, deposit Structural instability, loss of material, change of impressionConversion, visible Peeling, visible Visible Visible Structural instability, crack, loss of bond, visible Sanding, visible


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3. Classification through damaging pattern [What do you see?] A brief list of damage jargon with description is given here since it is not always easy to describe what you are seeing in situ in one word. This is the starting point for users of this Damage Atlas since the causes can be determined out of the observation of the damaging pattern.

Change of impression

Caused by new design due to renovation/reparation 32 and attack of beetles 94

Discoloration Fading5 : paint ‐ Loss of colour intensity or brightness of colour

Caused by water 49 and ultraviolet radiation (sun) 74

Staining5: a spot of distinct colour

Caused by water 50, polluted water 82, corrosion 73 and graffiti 83

Blackening: caused by fire 78

Deposit 5: material accumulated on the surface; exogenic (dust, dirt) / endogenic (efflorescence)

Caused by people and animals 91

Soiling5: is the exogenic deposit of uncrystalline and unconsolidated material (e.g. dirt, soot…)

Caused by water 51, air pollution 79 and root 85

Encrustation: is the crust‐like deposit with good adherence of whitish and dense mortar constituents

Caused by salts (leading to crust formation) 58

Efflorescence: is the endogenic formation of soluble (white) salts deposited on surface by capillarity Called crypto‐efflorescence if beneath the surface

Caused by salts 63

Visible biological growth (can be mistaken for a deposit) Higher plants: building material is used as substratum; determine their type by comparing images

Caused by growth of trees, plants and grasses 109, mosses 110 and fern 105

Lower plants: sometimes mistaken for mosses; determine their type by comparing images

Algae5: lower plants consisting of single cells or groups of cells

Caused by algae growth 102 and lichens (a combination of algae and mould) 103

Mould5: eucariotical micro‐ and macro‐organisms which subsist on dead organic matter

Caused by mould growth 98

Transformation5 involves a chemical conversion of the surface material Patina5: change of very thin surface layer protecting the underlying material from degradation

5 (Franke & Schumann, 1998)


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Caused by oxidation 86

Conversion: chemical alteration of the material (in combination with other damaging patterns)

Caused by moulds 99, water/air pollution 81, people/animals 90 and corrosion 70

Rotting: wood – (hemi‐) cellulose and lignin undergoes chemical alteration by microbes

Caused by water 52

Disintegration, loss of material or loss of cohesion

Caused by beetles on wood 93, caused by design renovation/reparation 31

Pitting: small pits formed by wind erosion 9

Crumbling5: adobe/bad brick ‐ Falling apart into small shapeless lumps

Caused by water (adobe) 67 and salt (brick) 56

Powdering5: brick – Loss of coherence starting from the surface resulting in fine powder

Caused by water 43 and salt 54

Sanding 5: mortar – Lack of cohesion due to granular disintegration

Caused by water 44, salt 55 and growth of mosses 111

Erosion5: abrasive wearing away of material creating a relief at the building material’s surface

Caused by wind 8 and water 41

Corrasion5: also called mechanical erosion, erosion by mechanical forces (use or impact)

Caused by an impact 16, mechanical forces during use 13 and polishing 15

Cut5: scratch (superficial loss of material), cut (line of division) or puncture (penetration)

Caused by mechanical impact 18

Layering subdivided into delamination and exfoliation Delamination5: separation of an originally laminated material into one or more layers

Caused by salts 61

Exfoliation5: separation of an originally homogeneous material into one or more layers

Caused by salts 62

Spalling 5: Detachment of a relatively thick part of surface

Caused by overloading 3, earthquakes 22, salts 60 and fire 77

Scaling5: Scale‐like detachment of a relatively thin part of the surface

Caused by salts 59

Loss of cohesion concerns a type of deterioration where the material is no longer bond Softening: The transformation of clay minerals changes adobe’s macrostructure by swelling

Caused by (excess of) water 68


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Loss of adhesion concerns the detachment of one material from another Peeling5: Detachment due to loss of adherence between surface and paint film or plaster finish

Caused by water 47

Blistering5: Dome‐like detachment of part of surface by local swelling/expansion (paint on plaster)

Caused by water (transport) 48 and salt 66

Loss of bond5: Detachment of mortar or rendering from masonry… (relatively thick layer)

Caused by water 46, corrosion 72 and higher plant growth (roots) 108

Cracks5: Lines of division which will go completely through the material (> 0,15 mm)

Caused by overloading 2, settlement 6, use 12, impact 17, traffic 19, earthquake 21, design error 35, water 57, diff. expansion 69, corrosion 71, fire 76 and plant growth 107

Crazing5: network cracking, a network of hair cracks < 0,15 mm

Caused by water 42 and salt 53

Deformation

Bulging5: Caused by water 45

Bending5: Caused by overloading 1, settlement 5, water 40

Leaning 5: Caused by settlement 4 and wind 7

Destruction: collapse or by purpose destruction of a (part of a) building

Caused by earthquake 20, design (combined with new construction) 30, fire 75

Risk

Error/risk Caused by error in the design process 33

Instability Caused by error in design 34, by beetles on wood 92 and higher plant growth 106

Wrong choice of material, technique or system in the design process can cause problems in the future

Caused by error in design 36

Incorrect use is introducing risks for the future

38

Intervention during reparation or the lack of intervention is a risk for future damages

39


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4. Classification through building state [What is the actual state?] For the conservator, historian, architect or engineer the actual state of the building is important for her or his inspection. Some buildings are just renovated and every damage pattern is or structurally solved or camouflaged by cosmetic repairs. There is of course a difference between extremely altered dwellings and carefully restored houses ( 50).

Most of the buildings are in a phase of degeneration or consolidation, no interventions are planned. Some major problems are clearly visible ( 74).

The most interesting observations are made in buildings under renovation. After removal of the surface layers and ceilings, the structure is visible and it is possible to follow the repairs day by day and to talk with the handicraftsmen ( 43).

5. Classification through severity [How bad or threatening is the damage?] Most problems such as graffiti are luckily aesthetical or superficial. But these damage patterns can evolve to more structural problems and indicate delicate places.

In a lot of other cases, the functionality of the material is lost by disintegration or a general loss of bond. In the first case, the material is converted by chemical or biological attack often combined with the presence of water. Material is also lost by different kinds of loss of adhesion (between 2 different materials) or cohesion (in 1 material). It is an ‐ often slow – irreversible process and should be prevented.

Cracks are commonly known as a structural and dangerous problem. Cracks often indicate structural instability, high vulnerability for earthquakes and a future collapse. But also superficial cracks (e.g. network cracking) can occur.

Structural problems such as deformation of structural construction elements, effects of fire and the intentional destruction of historical buildings are the most unwanted damages.

The order of the case studies is using this classification, through increasing severity of the damaging patterns and risks.


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II. Case Studies 1. Aesthetical and surface problems

Damage: staining (discoloration) Cause: chemical ‐ graffiti Building: Iglesia San Blas ( 1), Pasaje Hortensia Mata ( 27) Graffiti is typically an (intentional) human intervention, which causes (almost always) aesthetical unwanted staining. Older graffiti can attract other new ones. The location of the affected building is an important parameter; degraded neighbourhoods ( 49) or places of manifestation ( 118) are more suffering. Solution and Prevention: For plasters, paints and earthen layers, the best solution is to paint over the graffiti ( 279). For other materials such as brick and natural stone ( 252), there are 3 different preventive treatments possible (van de Weert, 2004). Epoxy or polyurethane pore filling resins are permanent, long lasting and resistant but their high diffusion coefficient causes problems in materials with high water content (such as adobe and bahareque). In contrary, an acrylic emulsion functions as sacrificing and temporary layer which can be washed off together with the graffiti. It is very useful since it is not hydrophobic and not preventing diffusion. A combination (semi permanent) is the optimal solution, but is predicted as more expensive.

Damage: soiling Cause: chemical – soot Building: Hotel Victoria ( 95) and Catedral de la Inmaculada ( 25) Although soot can cause unwanted blackening (especially on white painted chimeys, 262), no other solution is given than washing or repainting. We should mention that candles, where the soot is a witness ( 452), are a serious threat for the fire safety.

Damage: blackening (discoloration) Cause: chemical ‐ fire Building: Catedral de la Inmaculada ( 25), Edificio San Agustin ( 24) This kitchen ( 1469) is blackened during use. During the June 2008 fire the building was partly destroyed and this wall suffered from blackening ( 1040). Solution and Prevention: Fire should be prevented as much as possible, but blackening is not a threatening damage and will not evolve further.

83

85

78


15

49 118 279

252 262 en

452 1469 1040


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Damage: deposit Cause: biological – people and animals Building: Casa de las Palomas ( 74) Peoples and animals deposit such as faeces and bird nests ( 1105 and 1301) causes just aesthetical damaging patterns in most cases. Prevention can diminish the future maintenance costs.

Damage: change of impression Cause: biological – beetle / moth Building: Iglesia de Santo Domingo ( 59) Beetles can cause structural and disintegration problems, but in a lot of cases, just aesthetical problems are found ( 340, 377).

Damage: visible lichens Cause: biological – lichens (chlorophyllous) Building: Casa de las Palomas ( 74) Lichens exist in unpolluted environments, such as Ingapirca. They are not considered to cause damage. Since they are grey, they are probably “Diploicia canescens”6 ( 315)

Damage: visible fern Cause: biological – fern (chlorophyllous) Building: Catedral de la Inmaculada ( 74) Fern is a protected species and should not be removed therefore. It is not considered to cause damage ( 562).

6 http://www.lichenology.info/

103

105

94

91


17

1105 1301 340

377 315

562


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Damage: visible algae Cause: biological – algae (chlorophyllous) Building: casa Arizaga Guzman ( 39) These algae are greenish and grow in a shaded place (stairs between two high buildings). No direct sun radiation and exposition to rainwater are contributing to the growth of algae here ( 246). In this wet climate, there is a big risk for biological damage. The water source here is waterfall ( 167, 171, 172) and algae grow giving a black shine. Further research: To be sure, it is recommended to look after the formation of gypsum crust on cement. The black shine is than caused by air pollution.

Damage: visible higher plant (general) Cause: biological – higher plants (chlorophyllous) Building: El Chagra’s restaurant ( 207) This small restaurant is a typical remnant of traditional houses with only a ground floor in the historical city ( 218). Growth of higher plants is not harmful as such, but can be a witness of general lack of maintenance of the whole building.

Damage: visible moss (higher plants) Cause: biological – moss (chlorophyllous) Most occurrences of mosses are not very dangerous ( 227), but they can secrete acids which are harmful for mortars (see next case).

Damage: sanding of mortar Cause: biological – moss (chlorophyllous) Building: Catedral de la Inmaculada ( 25) Mosses do not have genuine roots, but rhizoids that secrete acids which dissolve the mortar binder ( 510). In very wet circumstances a relatively weak mortar can be turned into loose sand within one year (Franke and Schumann, 1998). Further research: Measuring the pH of the affected mortar can exclude other possible damaging causes. A low pH in combination with visible mosses, proves the growth of rhizoids. Some mortar tests were carried out in this building ( 25) (see page 34).

Damage: loss of bond Cause: biological – higher plants (chlorophyllous) Building: Iglesia de Santo Domingo ( 59) Higher plants and its roots can cause serious damage growing between tiles and bricks ( 1315). Maintenance is recommended to prevent higher reparation costs.

111

108

110

109

102


19

246 172

218 227

510 1315


20

Damage: efflorescence and blistering/peeling Cause: physical – salts Building: Catedral de la Inmaculada ( 25) In the tomb of the main cathedral salts were found in the first half meter above the ground. Rising damp is the damaging cause since the brick masonry is in contact with the ground. Next to (beautiful) salt efflorescence ( 449), blistering and peeling of the paint were found as well ( 456 and 694).

Damage: efflorescence Cause: physical – salts Building: Hotel Victoria ( 95), Catedral de la Inmaculada ( 25) Although initially designed to be finished with a layer of plaster and paint, naked masonry facades are characterizing calle Larga. Due to inadequate eaves, rain water is washing the bricks regularly introducing salt efflorescence after drying ( 257). Furthermore, after cleaning with water under high pressure, salts crystallized on the domes of the main cathedral immediately ( 516, 2078, see page 34). It is interesting to mention that salts were only found on bricks and not on earthen materials. However, it is very probable that high salt contents are present and causing damages to adobe and bahareque.

Damage: peeling (loss of adhesion) Cause: physical – water Building: Casa de las Palomas ( 74) Wood exposed to rain or a high content of moisture, will be damaged on its paint. It is known as an aging process when no maintenance is carried out. Peeling ( 604) and blistering is found. Solution and Prevention: In the case of wood, we can refer to a publication of Iowa University (1994).

Damage: blistering (loss of adhesion) Cause: physical – water Building: Iglesia de Deleg ( 228) Blisters mostly occur on paints with low vapour diffusivity attached on earthen materials such as adobe ( 694). Water (coming from condensation or drying processes, rain infiltration…) is prevented from evaporation by this paint and small spaces (bubbles) filled with vapour are growing. Paint is detached from the substrate and if the spots burst (already visible here), more water is introduced behind the paint. This is how the damaging pattern will evolve from innocent blisters to paint peeling and adobe softening. Prevention: Prevention is easy by using paint that allows vapour transport and by protection against water contact (rain and other sources).

63, 66

47

48

63


21

449 456

694 516

604 257 2078


22

Damage: fading (discoloration) Cause: physical ‐ water Building: Casa de las Palomas ( 74) The ceilings of the first floor of casa de las Palomas are made of zinc. Water infiltration from above introduces discoloration of the paint on this metal sheets ( 600).

Damage: staining (discoloration) Cause: physical ‐ water Building: Iglesia de Santo Domingo ( 59), casa de las Posadas ( 50),

la Bella de Paris ( 221) and la casa del coco ( 41) Red paint is washed out and deposited on the white paint on the wall ( 343). 685 of casa de las Posadas is made outside the project area. The road is in poor condition and on very

rainy days with heavy traffic water is splashed onto the façade (up to 2m high). The plaster on this recently restored colonial house (adobe) is in good condition which is accredited to the choice of good paint (allowing vapour diffusion). Rain water infiltration in patios is also a known problem though in this case watering the plants can also be an explanation ( 177). The restoration of la Bella de Paris is in many ways very successful. However, dealing with rising ground water is essential in the design. Inside walls are showing sever moisture stains immediately after construction ( 410). Furthermore, rising damp is not solved by applying cement mortar on the lower part of the wall ( 414). The ground water will rise above this plaster resulting in staining, loss of bond… A cement layer can only serve as protecting layer against splashing. Solution and Prevention: An impermeable membrane (or chiva) on the bottom is needed to stop the water transport.

Damage: staining (discoloration) Cause: chemical – metal corrosion Building: Catedral de la Inmaculada ( 25) The statue of Holy Santa Anna on the main cathedral is made of bronze and placed on brick masonry. The green staining is caused by corrosion of this statue ( 479). The powdering of the bricks is not correlated with the corrosion process (see page 32).

50

49

73


23

600 343 685

410 414

177 479


24

Damage: polishing Cause: mechanical – use Building: Casa de las Palomas ( 74) Stairs or steps are the most popular place to find polishing. The frequent and abrasive use of natural stone ( 592) has led to this shiny and slippery erosion. It is not considered as damage, but as a predictable weathering process. Therefore, solutions and prevention are not an issue here.

Damage: change of impression Cause: design – renovation/reparation Building: Hotel Crespo ( 108), Casa de las Palomas ( 74) The structural stability isn’t affected while introducing a new entrance in this hotel on calle Larga, but other effects are not less important ( 238). The total concept and harmony are changed forever while the functionality will probably increase. This operation gives a full view of the brick masonry that is hidden behind plaster and natural stone in normal conditions. Though lime plaster is frequently used without problems, the application of lime plaster is sometimes a debatable intervention ( 2028). We refer to the thesis for a more detailed discussion.

Damage: loss of original materials Cause: design – renovation Building: Catedral de la Inmaculada ( 25) It is thought that the light blue tiled domes – a symbol of Cuenca – of the main cathedral were completely covered. A closer look is showing cracks in the tiles (see II.3) and absence of tiles in the corners ( 504). Instead, we found cement mortar which, in first place, is only an aesthetical issue.

Damage: change of impression Cause: design – renovation / reparation Building: casa municipal de Gualaceo ( 245) New constructions in historical valuable dwellings need to be designed very carefully. This colonial building with typical patio and walkway is mutilated by a new concrete stair case which combines the wrong choice of location, material and geometry. The stair case is removed again after structural bearing problems ( 1638). The renovation of the old municipality of Gualaceo included new materials and techniques instead of the old ones, a doubtful new concrete stair case, the broadening of the entrance and the removal of bearing walls. All these interventions caused cracks and instability and therefore we refer to the case on page (see page 56).

15

31

32

32


25

592

238 2028

1638 504


26

Damage: change of impression Cause: design – renovation / reparation Building: Corte Superior de Justicia ( 19), casa del Coco ( 41) and

casa Sempertegui ( 119) Patios are typical for the colonial style and are used in nearly every dwelling in the historical city. The last decades, patios were covered by modern steel or wood constructions containing glass. The result doesn’t have to be an architectural disaster. One can judge for its one whether the dome on the Court was a good choice or not ( 21, 24, 22, 208). Mind the rebars to take the thrust and tensile forces in the corners ( 24). Also casa del Coco has a covered patio of metal and glass ( 180). Houses such as casa Sempertegui ( 838) and casa de las Palomas still have their original patio. Research: Some research was done by prof. arch. Pacurucu (thesis about patios in Cuenca). The aerial views by local promoter prof. arch. Cardoso make it possible to discover changes in time of patios… that are invisible from the street.

32


27

838 180

21 24

22 208


28

2. Disintergration (surface to structural problems) Damage: patina, spalling Cause: mechanical – overloading Building: Incan ruins of Ingapirca, Cañar ( 211) Different magmatic stone (igneous rock) types occur in this highly volcanic region. This volcanic rock (magma didn’t reach the surface) is the intrusive diorite stone because the crystals are visible ( 320). The green colour is a patina which indicates the presence and oxidation of copper. Due to stress concentrations caused by tourists walking on the remnants of the ruin in combination with very small or no joints, the stone was overloaded and developed cracks. A thick surface layer is pushed off finally ( 320).

Further research: Biological growth is also a possible cause, but in that case the color is deposited onto instead of into the surface. Organic materials can be identified by heating it with fire.

Damage: erosion, pitting Cause: mechanical – wind Building: Iglesia de la Virgen del Rosario de Biblian ( 217) This volcanic andesite stone developed small pits at the most vulnerable spots ( 333). The church is situated on a steep hill where an intensive wind blows. This wind is the main cause of the erosion.

Damage: corrasion (= mechanical erosion) Cause: mechanical – use Building: Convento del Buen Pastor ( 3) The corner of this adobe building is situated at calle Simon Bolivar and plazoleta de San Blas ( 73). The corner is protected by the use of hard natural stone whereby only the painted cement plaster is affected. At the corner of the Mariscal Sucre and General Torres street, it is more visible how natural stones are used for corrasion protection ( 814).

Damage: mechanical Cause: mechanical – impact Building: casa Herederos Bravo Narea ( 32) Making holes with a drill (impact) has led to the loss of cement plaster attached to brick masonry. This example also illustrates that nearly every building in calle Simon Bolivar is made of brick ( 150).

65, 3

8, 9

13

16


29

320 333

73

814 150


30

Damage: staining, bulging, loss of bond Cause: physical – water Building: iglesia de Santo Domingo ( 59) Water infiltration caused pull off of the paint ( 338). Moisture staining and bulging initiated this damage to the surface layer. At first, this damage doesn’t seem to cause further harm. But other beams suffered from structural instability after rotting of the end of the beam. At all time, contact of structural wooden elements with water should be prevented. Above this beam, a tiled roof in bad condition is found.

Damage: visible mould Cause: biological ‐ mould (non‐chlorophyllous) Building: iglesia Santo Domingo ( 59), iglesia San Francisco ( 114) The fruitbody of a mould is visible on this painted wooden ceiling ( 344 and 756). The type of mould is not known and further research is possible, but it is most probably the dangerous Serpula Lacrimans. It is not easy to treat this wood‐attacking mould, careful removal is recommended.

Damage: rotting and bending Cause: physical ‐ water Building: iglesia de Santo Domingo ( 59), casa Manosalvos ( 242) The wooden floor of this church is constantly wet. The source is definitely the ground in direct contact with the floor. The problem also exists where a cavity between the floor and the ground is made. This is due to the absence of natural ventilation. Stress concentration by swelling of the wood7 introduced deformation and bending of the elements ( 1318). The wood seems to be in a constant wet condition, there is no cyclical drying and wetting. In combination with the applied wax, there is no contact with the air which declares that there is – at first surprisingly – no gradual rotting process is found. Other damages will certainly be introduced when interventions to dry the floor are made. In casa Manosalvos water penetration has severely deteriorated the wooden bearing structure ( 1160). This picture is made at the basement beneath an overloaded and demolished balcony (see page 54).

Damage: disintegration of material Cause: biological ‐ beetle Building: casa municipal de Gualaceo ( 245) Beetles were allowed to damage this wooden door as far as you can see through it now ( 615). The structural stability was investigated in a wooden column ( 2101) by removing the affected parts and estimating the remaining section. The pops and eggs became visible.

7 Water and high humidity result in frequent wetting and drying cycles, which promote swelling and cracking of wood (Hughes et al, 2000)

50, 45, 46

98

93

52, 40


31

338 344 756

1318 1160

615 2101


32

Damage: sanding and erosion of mortar Cause: physical – water Building: catedral de la Inmaculada ( 25), iglesia de San Blas ( 1) The composition of the mortar in the main cathedral ( 1483) is investigated, as well as the deterioration by mosses (by measuring the pH, see page 34). Where the rain can penetrate, the mortar is leached or washed away ( 547, reservoir is flooded, see page 38). Water and soiling exist together. The upper 4 layers are disjointed from the base structure; collapse is possible in the near future ( 512). At some places whitish material, most likely precipitated calcite from dissolution of the mortar, is deposited as well ( 46, mind also the drainage pipe). Further research: Pointing hardness can be measured with the Schmidt Pointing Hardness tester (PM, PROCEQ SA, Swiss) providing a measuring head having a cylinder‐like shape (8 mm) and rounded at the measuring end (MDDS Compass, 2008).

The characterization of mortar can be done by determination of the dry density and porosity (RILEM CPC 11.3 method) and by microscopical and petrographical analysis (covering optical microscopy, X‐ray diffraction analysis, SEM‐EDAX…) to determine the type and volume fractions of aggregate, binder and additions (Compass, 2008).

Damage: softening and erosion of adobe Cause: physical – water Building: 200 and casa municipal de Gualaceo ( 245) Adobe has to be protected against excess of water. The main reasons for water infiltration are rain, splashing, rising damp or high relative humidity. This adobe wall ( 205) is protected against rain water by brick layers at the top. Splashing and ground or street water rise is not prevented. The deterioration starts from the foot by softening and erosion of the adobe. In most cases, the foot is protected by stones, bricks, tiles or a combination ( 673). Another threat for adobe are the built in drainage pipes. The risks are high and the damage is always big and the reparations are expensive. In this house, the problem was discovered after softening and erosion of the adobe wall ( 1483).

44, 41

68, 41


33

205 1483

1483 547 46

512 673


34

Damage: conversion Cause: biological – people and animals Building: catedral de San Blas ( 1), monasterio de Nuestra Señora de

la Concepción ( 99) People in Cuenca have the bad habit to pee where (small corners are preferred and churches are not skipped) and when they want. This man was caught on picture in action ( 44). Afterwards, the powdered brick and eroded mortar is clear together with the remnants of a cross. Also the pavement is renewed, but affected again. Only the river stone is inert to this attack ( 48). Prevention: The problem can be solved by installing public toilets or – more effective – by constructing crosses on high‐risk places ( 270).

Damage: powdering of brick, erosion of mortar Cause: physical – water Building: catedral de la Inmaculada ( 25) Regularly rain water is standing in the reservoir, bricks and mortar are severely attacked ( 513, 514). The whitish deposit can be efflorescence of salts, but also precipitated calcite from the dissolved mortar. Powdering of brick will happen faster when the firing has found place at low temperature. This means that there was only little vitrification and the material was not completely converted into the necessary glass‐like amorphous solid. The clay particles are only loosely bonded and contact with water will dissolve them and wash them away.

Damage1: powdering of brick, erosion of mortar Cause1: physical – water Damage2: efflorescence Cause2: physical – salt Damage3: erosion Cause3: mechanical – wind Building: catedral de la Inmaculada ( 25) This wall (back of the pedestal of Saint Anna’s statue on the main cathedral) is affected clearly by rain and wind erosion ( 554). Salt efflorescence is also visible and joining the deterioration process. Don’t mind the green stain at the right; they are caused by corrosion of the statue. The remark on brick powdering and vitrification in the previous case is also valid in this case.

Damage: scaling (exfoliation), crumbling, efflorescence Cause: physical – salt Building: iglesia de Santo Domingo ( 59) The bottom of these tiles is affected by penetration of rain water. Small surface layers are scaled, the tile is crumbling and efflorescence of the deteriorating salts is visible on the tiles and on the mortar ( 1227).

90

43, 41

43, 41

8

63

59, 56, 63


35

44 48 270

513 514

1227 554


36

Damage: Erosion (mortar), powdering (brick), soiling Cause: Combination of air pollution, rain and wind Building: Catedral de la Inmaculada ( 25) Some roofs are made of brick masonry comprising brick and mortar (e.g. 59 and 25). The roof of la catedral de la Inmaculada is entirely exposed to rain since it is unprotected. Mark the difference in exposure and therefore also brick vulnerability between vertical walls and, in our case, horizontal roofs. On the other hand, air pollution is a major problem due to the burning of fossil fuels of traffic. Compared to other South‐American cities (Quito, Sao Paulo, Santiago…) the problem is less severe in this smaller and relatively isolated city. Also the high altitude which allows lower octane fuels and thus lower aromatic components is an advantage. But the problem is bigger than in Europe or other developed countries. Use of leaded oil, more limited refinery capabilities and not adopted cars are leading to dangerous exhaust and bad air quality. SO2 and NOx are the primary and most harmful components (Sollars & Gee, 1997). First the mortar is leached out; afterwards the bricks can start powdering but generally remain in good condition ( 482). The influence of orientation of wind and rain is clear ( 1484 where the left side is exposed and severely attacked unlike the right side). Typical black soiling is occurring at both the bricks and joints ( 482). Research: The pH of the soiling deposit is measured ( 1729, resulting in pH 6). A simple pull‐off test is carried out to determine the state of the bricks by the cohesion and tensile strength ( 2079). Both tests are carried out by arch. Wilson Pacurucu (Universidad de Azuay). It is also recommended to investigate the damaging mechanisms more in deep. The concentration of different contaminants in the air and rain as well as the engine exhausts can be a future thesis topic. Solution and Prevention: Although soiling is not a structural damage, it is unwanted on one of the symbols of the city. Cleaning with water under high pressure seems to be the only possibility but not without danger ( 478, see next case study). Soiling can be prevented on different levels. On national level legislations for better oil refinement and cars is needed, on local level the city center can be made car free. Since these long term options are not likely to get implemented soon, prevention with surface treatments should be considered.

Damage: Incorrect intervention Cause: Maintenance Building: Catedral de la Inmaculada ( 25) Since the black soiling is unwanted, high‐pressure water treatment is used to successfully remove it ( 478). It is likely that the soiling served as protecting layer for the bricks against weathering processes which is now lost. Furthermore the porous bricks are extremely wet and due to the wet climate, it is impossible to dry profoundly (especially for the second and slow drying period of a brick). Efflorescence ( 2087 and 63) is proving this problem. The planned application of hydro repellent will have a disastrous effect. The water will evaporate at the interior side of the dome, causing moisture spots and spalling of the plaster since no effective outside repellent can have a higher diffusion coefficient than the plaster. The solution is a (temporary) shelter and (natural) ventilation to allow drying.

41, 43, 51, 79

39


37

1484 1729

482

2087

2079 478


38

Damage: loss of bond Cause: physical – water Building: convento de Buen Pastor ( 3), casa de las Palomas ( 74) Problems with drainage and eaves are very common. The main reasons are broken tiles or drainage pipes. Traditionally the eaves are built up from wood and finished with reed (carrizo) and (cement or lime) plaster (see page 42). When (rain) water infiltrates, these materials cannot cope with this; the reed starts rotting (presence of water and oxygen) and the plaster softens and falls of under its own load. The examples are plentiful and diverse ( 72, 632).

Damage 1: loss of bond Cause 1: physical – water Damage 2: bending (deformation) Cause 2: mechanical – overloading Building: casa de las Palomas ( 74) Also inside the dwellings, water infiltration causes harm to traditional ceilings from wood, reed and plaster ( 2140). The plaster comes off and, when badly repaired with cement, suffers from overloading ( 2160).

Damage 1: loss of bond Cause 1: physical – water Damage 2: no intervention Cause 2: design – maintenance Building: casa Eljuri ( 16) and Vieja hospital de Gualaceo ( 247) Brick ( 102 and other examples 152 and 301). It is not sure if there was ever an earthen layer (revoque) applied on this bahareque side wall ( 204). Anyway this protection should have been applied, especially when such small eaves (corrugated steel plates) are found. Water washes away the earthen layer when exposed to rain. In this case, the primary and secondary structure of bahareque is visible. It seems that this bahareque wall was filled. The protecting earthen layer is lost due to a lack of maintenance. Rain water washed the exposed earthen layer away ( 1956).

46

46

1

46

39


39

72 632

2140 2160

102 204 1956

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41

551 1747

531 (and 536) 493

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42

Damage: General design error / risk Cause: Design Building: Catedral San Francisco ( 114), Casa las Palomas ( 74),

Monasterio de la Concepción ( 99) The risks are high for bad water drainage since the resulting damages are always big. Special care should be undertaken with the details starting from the design ( 892). Problems in the past should be structurally solved with modern aesthetical ideas. Frequently found in historical buildings in the city center of Cuenca, are the drainage pipes bricked up in the walls ( 268, 2195). The smallest leakage leads to interior disintegration ( 2074). When the problem becomes visible ( 727, see next case), interventions come too late.

Damage: Loss of bond Cause: Physical ‐ water Building: Catedral San Francisco ( 114) Loss of bond in this case is the erosion of adobe occurring where the wall is not protected by an adequate shelter or roof. The Terra project (Terra Literature Review, 2000) talks about a typical pathology of earthen architecture. Here the drainage canals for rain on the upper roofs are broken and badly repaired. The upper earthen layers and underlying softened adobe disintegrated and the material was lost ( 727 which is visualized by arq. Lourdes Abad). The rain water is coming from the main roof and after collection in a canal (coming out of the paper) redistributed by canals of tiles ( 892) running through the small wall under a smaller roof (illustrated in a section). The critical points are encircled.

46

33


43

2074 2195 268

727 (above) 892 (under)


44

Damage: Soiling, sanding of mortar Cause: Physical – water Building: Casa Campoverde ( 107) The soiling occurring on these eaves is a witness of bad detailing and bad choice of material ( 253). The rain water (coming from the roof) deposits dust and dirt. Furthermore, the penetrated water dissolved the mortar. Therefore, falling bricks are predictable in the future. Choose for roof tiles instead of simple bricks at the top of walls.

Damage: General design risk / error Cause: Physical – water Building: Museo de los Metales ( 81), Monasterio de la Concepción (

99), Casa Serrano ( 246), la Bella de Paris ( 221) Most eaves in historical buildings are made of bamboo like carrizo. The lack of maintenance of buildings ( 1615, 1619) illustrates the construction method after the loss of material. Though, it is perfectly possible to use this material if rain water is not in contact with this material. Roof tiles (or corrugated steel) and detailing of the eaves are necessary. In some cases, a sufficient crossing of the eaves isn’t provided ( 2133) and this will expose the walls to rain or weathering in general. Solution: It is perfectly possible to build up a good traditional roof. La Bella de Paris in Oña is a perfect example where first a layer of well‐attached reed on the wooden structure is applied and afterwards an impermeable sail (chiva) ( 413, 415). The roofing tiles are placed on an earthen thick layer, but it is not sure how this is attached on the underlying structure.

51, 44

33


45

253 1615 1619

413 415

1106 2133


46

Damage: Staining Cause: Physical – water Building: Catedral San Francisco ( 114) In catedral San Francisco, the most explicit example of rising damp is found (interior 757 as well as exterior 731). The source is ground water since the damage is also found at the interior columns (see dark grey parts on plan, 747). The height of the rising damp was measured at different places and found to be around 1m30 (see 748). It is important to tackle the cause of this damage. Although staining is only an aesthetical problem (see next case), it is the early stage of greater damage.

Figure 2: Part of the ground floor of catedral San Francisco ( 114), the light grey parts (outside walls) are composed walls,

the dark grey parts (mainly interior columns) are made of brick. Both are affected with rising damp.

Damage: Softening Cause: Physical – water Building: Catedral San Francisco ( 114) We discovered softening of the earthen material after we tested the penetration of a thumb in an affected wall (light grey part on the plan, 764). The cause is definitely rising ground water (although no salts were found) which causes an excess of water content. We are dealing with composed walls (river stone, adobe and brick) which are commonly used in the lower parts of ground floor walls ( 658). The real composition is unknown, so it is not sure if the softening of the wall is rather a surface or a structural phenomenon. Further research: A standard method including (destructive) sampling and a measuring technique is designated. Main aim of this method is to determine the quantity, distribution and origin of moisture in a wall (actual moisture content) and to obtain information on the presence and distribution of (hygroscopic) salts (hygroscopic moisture content) (MDDS, 2008).

Damage: Loss of bond Cause: Physical – water Building: Catedral San Francisco ( 114) Loss of bond is a final result of the damaging process mentioned in the previous case ( 757 and not in iglesia San Francisco 327). To prevent loss of bond and other surface damages, a sacrificing or in this case a protecting layer of high‐speed building brick is used ( 298). One should remark that the source of the rising ground water is not tackled with this intervention.

50

68

46


47

298 327 (also 658)

757 731

747 (also 748 and 768 to 770) 764


48

Damage: Loss of material (conversion) Cause: Chemical – metal corrosion Building: Staircase ( 255), casa de la Bienal de Pintura ( 43) This metal street light is corroded at the bottom ( 2010) and stability is not ensured anymore. The zinc ceiling in casa de la Bienal de Pintura (under renovation) is affected by rain infiltration ( 971). In both cases metal is lost.

Damage: Crack, loss of bond Cause: Chemical – metal corrosion Building: casa Montesinos Arce ( 28) This balcony is made of concrete but the necessary coverage of the rebar isn’t fulfilled ( 129). Part of the concrete is pushed off after the steel was corroded and increased in volume.

70

71, 72


49

2010

971 129


50

3. Surface cracks Damage: network cracking Cause: physical – (differential) expansion Building: casa Eljuri ( 16) and convento del Buen Pastor ( 3) Aging of paint and probably also thermal stresses ( 103 and 74). On the last picture, the paint also seems to have low vapour diffusion coefficients, preventing necessary moisture transport from the underlying earthen layer. Peeling of the paint is a result. This is an unglazed ceramic tile affected by wind, rain and air pollution. The surface is weathered and is not resistant to thermal stresses anymore ( 561).

Damage: crack (network cracking) Cause: physical – differential expansion Building: casa de Loza ( 30) Glazed tiles have a ceramic body and a glazed coating ( 147). This coating suffers from network cracking. It is possible that due to the different coefficients of expansion (COE), stresses are introduced between the body and the coating.

Damage: network cracking Cause: physical – water Building: ( 255) ( 43) Drying shrinkage ( 435, 322 and 2136) is a frequently seen damage to earthen materials (adobe, revoque on bahareque). The use of too high amounts of water during the production of adobe is causing (network) cracks. Neumann tested the influence of drying shrinkage cracks on tapial walls. He found that these cracks do not influence the shear resistance and that they can be treated as cosmetic in nature and can be covered in the wall finishing process (Vargas Neumann, 1993). We can extrapolate these results to adobe masonry as well. Concerning earthen materials, the more swelling clay is present, the more shrinkage on drying one must expect. In the case of adobe, the loss of water shrinks the material into the final shape. Volume loss can often reach 20%. Shrinkage must occur toward the center of the object in the mold, so that few cracks are formed (Terra, 2000). Solutions: Respect the limits of the moulding moisture contents between 5 and 18 % (De Jongh & Van Wijnendaele, 2009). In addition, the shrinkage of the clay masses can be significantly influenced by the common practice of adding other materials—such as vegetal matter, lime, or calcite—which may serve as binders. However, before such generalizations can be drawn, more precise investigations must be made into the types of material used and their mineral plus organic material content (Terra, 2000). Further research: R. Hartzler (1996) advocates linear and volumetric shrinkage testing, in accordance with ASTM standard D4943 with a view toward predetermining the presence of unstable clays (such as montmorillonites, smectites, and bentonites). In addition, A. Demehati (1990) suggests that a “relative shrinkage” (RS) value should be taken into account.

69

69

42


51

103 74

147 561

435 (and 206) 322 2136


52

Damage 1: network cracking Cause 1: physical – water Damage 2: crack Cause 2: mechanical – settlement Building: house in Oña ( 224) The typical pattern of the slanted shears can indicate settlement of the right part of the dwelling while the wall on the left did not settle (differential settlement). We should mention that the left wall is from bahareque while the right part is adobe. The network cracking in the earthen layer is most probably caused by drying shrinkag. The house is in a general bad condition and for sale ( 440).

Damage: cracks Cause: physical – (differential) expansion/shrinkage Building: la Bella de Paris ( 221) The cracks (horizontal and vertical) have the geometry of the adobe bricks that were placed after the general construction of the wall ( 1177 and also 1182 in SaMat Doccenter). Probably, the older adobe bricks had a lower moisture content after a longer drying period. The new adobe bricks shrunk in situ causing these specific aesthetical cracks in the earthen layer (revoque).

Damage: network cracking Cause: physical – water Building: casa Manosalvos ( 242) The earthen layer (revoque) ( 2136, left) is applied on the reed (right) new bahareque. It is almost impossible to prevent drying shrinkage cracks (network cracks) and therefore a lime plaster (empaneite) serves as finishing layer. This is good workmanship.

4. Structural cracks

Damage: (structural) crack Cause: mechanical – settlement Building: casa de las Palomas ( 74) The crack is situated on the transition between the massive front bay and the wing at the back. It is mostly probable that differences in settlement caused this quasi‐vertical crack. There is no evidence that this crack is also structural and not only superficial ( 593).

Damage: (structural) crack Cause: mechanical – settlement Building: iglesia de Santo Domingo ( 59) The crack is definitely caused by the differential settlement between the church itself and the two heavy towers of the church ( 371). The crack is also found at the other side of the wall and wider at bigger heights. These types of cracks are a danger for the stability of the church.

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Damage: leaning, structural crack Cause: mechanical – settlement Building: iglesia de Santo Domingo ( 59) The wall of the oldest part of the convent (17th century, marked brown on air photo, at the right on 1244) is leaning towards a new building of high‐speed building brick (‘70s, marked red on air photo, at the left on 1244). The cracks between the old and new building are wider at the highest floor ( 1267) and discovered in each corner ( 561).

Damage: (structural) crack Cause: mechanical – overloading Building: la casa del Coco ( 41) Stress concentrations at the beam in this adobe (or bahareque) wall caused this one meter long crack ( 174, wider at the top). Other examples of the same problem are mentioned in Samat Doccenter at 328, 394, 395.

Damage: (structural) crack Cause: mechanical – overloading Building: casa Manosalvos ( 242) This very heavy staircase made of natural stone was introduced on the balcony during the last renovation. This overloading contributed to the settlement and later on the partial collapse of the whole balcony. Bad water drainage has led to rotting and collapse of the supporting beams (see page 28). The cracks in the stair case are declared by the settlement of the balcony ( 1179).

Damage: (structural) crack Cause: mechanical – seismic Building: house in Pisco, Peru ( 242) These pictures are taken by Marcial Blondet after the August 15, 2007 earthquake in Pisco, Peru. The M8 earthquake with epicenter in Pisco was the biggest in 50 years in Peru having more than 500 people killed. After this earthquake, also 80% of the adobe houses collapsed or were severely damaged while brick buildings kept standing ( 1334). Main reasons are the high weight and the brittle failure of adobe masonry. The typical diagonal parallel cracks in the corners of windows illustrate the seismic in‐plane damaging mechanism ( 1336). Out‐of‐plane shaking causes vertical cracks in the corners between walls. These pictures are included to illustrate the high risks for historical adobe dwelling in Cuenca in the same seismic region.

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58

Damage 1: structural instability Cause 1: design Damage 2: structural crack Cause 2: mechanical ‐ overloading Building: casa municipal de Gualaceo ( 245) This is probably the best example of a completely wrong renovation in an adobe dwelling. Walls of tapial were removed or opened at the ground floor ( 1637) and the entrance was made bigger ( 1620). The new structural elements (pitched metal trusses 1511, concrete beams) could not replace the massive structure. Enormous cracks (depth 63 cm, 1648) are introduced at nearly every intervention ( 1506, 1513). A complete illustration of the main problems at the entrance is given on Figure 5. The renovation works included also earlier mentioned interventions (see page 24).

Figure 5: Vieja casa municipal de Gualaceo, a bad renovation

34

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Damage 1: structural crack Cause 1: design Damage 2: structural crack Cause 2: mechanical – overloading Damage 3: structural crack Cause 3: mechanical – seismic Building: vieja hospital de Gualaceo ( 247) In the corners of the rooms of the old hospital of Gualaceo, structural cracks are found ( 1541, 1946). Although the direct cause cannot be declared immediately, we should search for overloading by horizontal forces. The dwelling is standing free in the field so wind forces can play a certain role (shear lag effect). Seismic forces (out‐of‐plane movement) can cause these cracks, especially since the walls are not connected anymore by any roof structure ( 1556). Absence of connection is also a design problem of the past ( 2108). The development of these structural problems is improved by the wind and rain erosion of the earthen materials (adobe, tapial 1947). Solution: Part of the solution was carried out by arq. Monica Pesantes in 2008 ( 1943, 1969). Adobe masonry replaced the old tapial construction. Wooden connections between the two walls (1m50 in each wall) were introduced as well at certain heights (3 times in total).

35

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5. Other structural problems

Damage 1: structural instability Cause 1: biological – beetle Damage 2: structural crack Cause 2: mechanical ‐ overloading Building: casa municipal de Gualaceo ( 245), Museo Municipal de Arte

Moderno ( 46) and casa de los Arcos ( 134) Wooden columns are often used in Cuenca and their structural functionality is important. Attacks from beetles ( 2127) and vertical splitting ( 830) of the columns should be taken serious and investigated well. Which is the remaining section of an affected column? How can different parts work together after splitting? Filling the cavities with not adapted cement mortar can be dangerous since the cement can introduce expansion stresses ( 869).

Damage: structural instability Cause: design Building: catedral de la Inmaculada ( 25) The middle small dome is not perfectly spherical. Since the dome is made of bricks and its structural thickness is only around 20 cm (!), the shape is really decisive for the stability of the dome. This picture shows a sideview of the dome ( 501).

Damage 1: bending (deformation) Cause 1: mechanical – overloading Damage 2: structural crack Cause 2: mechanical ‐ overloading Building: casa Manosalvos ( 242) The front wall is detached from the interior structure since it started to lean under the horizontal forces introduced by the load on the roof ( 1190). Now, an entirely new roof is made ( 1188) but thrust forces are still present (see Figure 7). Part of the vertical load is taken by a vertical column in the middle. This results in a big point load in the middle of the horizontal beam. This beam is bending and not attached properly to the wall. Therefore, it is not taking any horizontal forces.

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Damage: destruction and structural instability Cause: chemical – fire Building: edificio San Agustin ( 24) This corner house built in 1932 with elements of Neoclassicism and Art Deco was renovated in the 90’s to an office building. The first two floors are made of adobe, the two highest floors of bahareque. The façade is made from brick. During the June 2008 fire the building was completely attacked. The two highest floor were completely destroyed ( 1045).

Damage: leaning Cause: chemical – settlement Building: vieja hospital de Gualaceo ( 247) The façade of the old hospital was shored since instability and loss of connections with other walls occurred. This wall is standing on its own at this moment. A picture of the basement made of stones can be found on 2107 in SaMat Doccenter.

Damage: bending (deformation) Cause: mechanical – overloading Building: casa municipal de Gualaceo ( 245) Bending (3 cm in the middle) occurred at overloaded beams mentioned earlier. It seems that the wooden beam is taking some loads. Mind the small crack as well ( 1700).

Damage: bending (deformation) Cause: mechanical – overloading Building: casa de las Palomas ( 74) This ceiling from reed (carrizo) and earth was renovated to a cement plastered ceiling. The extra weight caused bending of the ceiling which is not attached anymore at one side. A long‐term solution is needed ( 2160 and also 620 and 1889).

Damage: deformation and structural crack Cause: mechanical – settlement Building: collapsed building in construction ( 257) This building entirely collapsed after a land slide. The building was under construction while the ground moved under the load ( 2117). Further geological information is missing.

Damage: lack of maintenance, no intervention Cause: maintenance Building: house near Cajas ( 250), casa Serrano ( 246) in Doccenter A lack of maintenance and necessary interventions made this abandoned house uninhabitable ( 1660). A lot of rural houses are found to suffer from fast degradation after they are left behind.

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