This article was downloaded by: [York University Libraries]On: 23 September 2014, At: 14:23Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: MortimerHouse, 37-41 Mortimer Street, London W1T 3JH, UK

Architectural Science ReviewPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/tasr20

Adobe Construction: A Case Study in TurkeyLeyla Tanaçan aa Faculty of Architecture , Istanbul Technical University , Taskisla, Taksim, 34437,Istanbul, TurkeyPublished online: 09 Jun 2011.

To cite this article: Leyla Tanaçan (2008) Adobe Construction: A Case Study in Turkey, Architectural Science Review, 51:4,349-359

To link to this article: http://dx.doi.org/10.3763/asre.2008.5139

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) containedin the publications on our platform. However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose ofthe Content. Any opinions and views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be reliedupon and should be independently verified with primary sources of information. Taylor and Francis shallnot be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and otherliabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to orarising out of the use of the Content.

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Architectural Science Review Volume 51.4, pp 349-359

Adobe Construction: A Case Study in Turkey

Leyla Tanaçan

Faculty of Architecture, Istanbul Technical University, Taskisla, Taksim 34437, Istanbul, Turkey

Corresponding author: Tel: +90-212-293 1300 (2211); Fax: +90-212-251 4895; Email: tanacan@itu.edu.tr

Received 4 June 2008; accepted 29 August 2008

Abstract: Adobe has been used as a construction material for hundreds of years, and even today, a great number of people still live in adobe houses in various parts of the world. This is for reasons of local availability and because buildings constructed from adobe can create healthier environments. As a case study, this paper analyses a building complex made primarily of adobe masonry and reinforced concrete. The complex, a country club located 35km from Istanbul, consists of a 19-room hotel, a restaurant, and a horse stable. Both the hotel and restaurant were constructed in two flats of locally produced adobe and have been in service since 1998. This paper describes the construction techniques and methods used to produce the adobe. It presents experimental tests of the mechanical and physical properties of the material, comparing to local construction standards and to the properties of other common building materials. Finally, the paper evaluates the suitability of adobe masonry construction for the Istanbul area.

Keywords: Adobe, Building materials, Housing, Masonry construction, Mechanical and physical properties, Reinforced concrete

IntroductionEarth buildings can be found on every continent, some

having been occupied even thousands of years (King, 1996). It has been widely used in Anatolia since prehistoric times (e.g., in Çatalhöyük & Hacılar); (Naumann, 1975). There is a growing interest in the use of earth as a construction material for two reasons; the heritage factor and because it is environmentally friendly (Carmen, Jimenez, Delgado & Guerrero, 2006). A study of traditional building practices throughout the world identified some 18 different methods of using the material, each able to produce a great variety of forms (Guillaud & Houben, 2001).

As a developing country with a growing population, Turkey suffers from an acute housing shortage. It is anticipated that the housing units needed by 2010 will be 7.5 million. A major factor affecting the construction industry is the cost of fuel and building materials, most of which have to be imported. The most common building material for construction of houses in rural areas is the usual burnt clay brick (Binici, Aksogan & Shah 2005). Building with adobe offers many advantages, including:

• It enables cheap, easy, and fast production;• It allows people to use local materials and to take charge

of the production of their built environment; • It doesn’t need a special plant for production, saving

money and energy in terms of production and transportation;

• It has adequate thermo-physical and hydric properties which contribute to the regulation of thermal comfort of the building, hence decreasing its life-cycle costs;

• It produces little pollution, both during manufacture and through the life of the building; and

• It plays a part in the respect for, as well as the survival and updating of, cultural, architectural, and urban environments (Guillaud & Houben, 2001).

Two important factors have to be considered when building with adobe. First is its water retention. It has to be protected from water and rain during its service life. The other factor relates to the need for care in its production and use during construction (Kafesçioğlu & Gürdal, 1985). Issues such as stability, compressive strength, and integration with other materials become critically important with adobe.

Stabilization of adobe refers to any treatment that gives it properties such as water permanence, strength, and dimensional stability. Although it has been practiced for a very long time, it is still not an exact science (Guillard, Joffroy & Odul, 1995). Compression and drying both help to stabilize adobe. In addition, there are more than a hundred products in use today for stabilization. These include sand, gravel, fibers, bitumen, resins and chemical products, cement, pozzolana, lime, and gypsum. These materials increase density, strength, cementation, bonding, waterproofing, and elimination of water dispersion. For cementation, some efforts have been made with promising results (Guillard, Joffroy & Odul, 1995; Isik & Tulbentci, 2008; Millogo, Hajjaji & Ouedraogo, 2008; Pineda-Pinon, Vega-Duran, Manzano Ramirez, Perez-Robles, Balmori-Ramirez & Hernandez-Landaverde, 2007).

www.earthscan.co.uk/journals/asre doi:10.3763/asre.2008.5139

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

Architectural Science Review Volume 51, Number 4, December 2008350

There is a tendency at present to stabilize systematically, but stabilization is not obligatory. As Fathy (1973) has warned about adobe production, “Expensive methods of stabilization are unnecessary. Once a sufficiently strong brick has been made, leave well alone.” He continues:

“The composition and properties of soil used in adobe production varies widely from place to place. In addition, this variation is likely to be reflected in the quality of adobe, a fact that has caused architects and engineers to be reluctant to use such blocks. Because of this reason, it is essential that at any given site the soil to be used for adobe making must be carefully analyzed chemically and physically. Experiments and laboratory tests on sample bricks must be made to determine the physical properties like shrinkage, unit weight, behaviour under wetting or mechanical properties like compressive and flexural strength” (Fathy, 1973).

To explore these issues, this case study investigates the properties of adobe utilized in a country club, which has been in use since 1998. By analyzing its mechanical, thermal, and acoustic performance during its service life, the case study explores whether adobe is a suitable construction material for the conditions of the Istanbul region.

Construction DetailsThe Sakliköy Country Club is located 35km from Istanbul,

Turkey. The complex comprises a 19-room, two-story hotel, a two-story restaurant, and a horse stable. All were built using locally produced adobe. While the stable and restaurant employ adobe masonry construction, the hotel consists of a concrete skeleton, with adobe blocks used for both interior and exterior walls.

Istanbul lies at latitude 41° north, and the sample buildings face to the south. The average temperature of Istanbul is 3.3°C for January, and 24.4°C for July. The temperature at the site is generally 1 or 2 degrees cooler than in the city.

Figure 1 shows the adobe masonry construction. As a foundation, reinforced concrete walls of 40cm in thickness are used. For seismic conditions, foundations must be strong.

Above this concrete foundation, a stone wall is constructed; both as a base for the adobe wall, and in order to give a stone appearance. This wall has the same thickness as the concrete wall, 40cm.

A ring beam, made of 10 x 10cm wood with reinforcing steel wire, lies atop the stone foundation. Second and third ring beams are built at an intermediate height in the masonry at the level of the lintel (see Figure 2). The main role of the ring beams is to absorb horizontal loads. Ring beams improve the stability of the walls by reducing the concentrated pressure of earthquakes with high tensile and bending stress. They also help distribute vertical loads evenly, stiffen the walls to reduce the risk of buckling, and serve as anchors for the floors and roof (Guillard, Joffroy & Odul, 1995). Note that to ensure the efficiency of the reinforcement, the adobe blocks must bond well to the wood of the ring beams. The outside and inside ring beams are tied together with steel wire at 50cm intervals. The space between them is filled with cement mortar. Then earth mortar, approximately 2cm in thickness, is laid over the wood and mortar base. In order to prevent capillary water that may come from the ground, a damp-proof course is laid beneath the wood beams and cement mortar. The walls are made with adobe blocks of size 27 x 12 x 9cm and plastered over. Blocks are used both in load bearing walls and in the reinforced concrete skeleton system as infill masonry in the site, so this size gives the material, which is very easy to handle, and very flexible in the way it can be used for many configurations of wall and building systems. Adobe walls are laid in alternate courses of headers and stretchers, commonly known as English Bond. Bonding patterns play an essential part in ensuring the cohesion, the stability and the strength of masonry structures built from small elements bonded together with mortar. The width of the mortar joints, both horizontal and vertical, is even and a minimum of 1.5cm and must not exceed 2cm to avoid cracking. Thus, crushing of the adobe under the effect of the weight of the wall itself or of a concentrated vertical load is prevented in horizontal joints. Mortar is used in a plastic state in order to ensure good mechanical bonding between the masonry elements making up a wall. All these factors as well as the material strength

4

Figures

Figure 1: The construction of the adobe masonry wall with English bond. Figure 1: The construction of the adobe masonry wall with English bond.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

351Leyla Tanaçan Adobe Construction

enable to reduce earthquake loads by using the thickness of the load-bearing walls.

The roof is covered by a wooden structure and the width of the eaves is 1.5m in order to prevent the wall from getting wet by rain (see Figure 2). Besides, certain precautions were taken against erosion driven from rain during the design stage; at the ground floor of two storey buildings, adobe masonry walls are protected by the balconies (Figure 3), arcades (Figure 4), or built in stone masonry (Figure 5).

In the hotel building, which is constructed with a concrete skeleton system, the exterior adobe walls are built with total thickness 33cm (1 adobe block +plaster), while the interior partition walls are 18cm (1/2 adobe block +plaster) thick. In all buildings, except the stable, 3cm of earth plaster is used as a rendering material on both inside and outside adobe walls. Infill adobe masonry of concrete framework limits the risk of crushing occurring under horizontal loads.

Adobe Construction All the information related to the production of adobe blocks

was obtained from the artisans who worked at the construction site.

MaterialsEarth: Earth used during the production is excavated

from 15cm below the surface of the site. It has almost a black colour. It does not contain lumps, stone or plant roots. It is not silty, and is slightly moist. The amount used in the mixture is 80 handcarts.

Sand: Washed river sand of 1-3mm grain size is used. The amount used in the mixture is 20 handcarts.

Straw: Straw has medium-size fibers. It is reaping-threshing machine straw. Three straw bales are used in the mixture. Each has dimension 40 x 60 x 120cm.

Fertilizer: Natural fertilizer is used. Cow manure is added to the mixture to improve the cohesion and plasticity of soil of low clay content as well as helping flocculate soils containing expansive clay. Sometimes the manure is applied to the mud plaster when partially dry to help stop the development of cracks. Likewise, it is used in various parts of the world to improve bonding and water proofing (Moquin, 2000). The amount of the fertilizer is 1.5 handcarts.

Water: As much as the mixture needs for enough consistency.

5

Figure 2: The walls are horizontally reinforced by embedded ring wood beams at

approximately 100 cm levels.

Stone foundation

Adobe wall

100

100

40 cm

150

5

Figure 2: The walls are horizontally reinforced by embedded ring wood beams at

approximately 100 cm levels.

Stone foundation

Adobe wall

100

100

40 cm

150

Figures 2a & b: The walls are horizontally reinforced by embedded ring wood beams at approximately 100 cm levels.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

Architectural Science Review Volume 51, Number 4, December 2008352

6

Figure 3 Hotel Building-balconies protect the walls from rain underneath.

7

Figure. 4 Restaurant Building- arcades protect the adobe wall of the ground floor.

8

Figure 5 Restaurant Building-walls of ground floor faced to the south built in stone masonry.

Figure 3: Hotel Building – the balconies protect the walls from rain underneath.

Figure 4: Restaurant building – the arcades protect the adobe wall of the ground floor.

Figure 5: Restaurant Building – the walls of the ground floor facing to the south are built in stone masonry.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

353Leyla Tanaçan Adobe Construction

MixingThe basin for mixing the constituents is constructed of clay

bricks. The dimension of the basin is 25 x 700 x 1200cm. Its floor is covered by cement screed. There is also a drainage channel at the floor level. Three basins are constructed side by side, in order to allow parallel production. After the materials are put in the basin, they are mixed two times a day for at least one week. The mixing aims to prevent the straw from decaying. After one week, the mixture acquires the consistency of cement paste, and the cover of the drainage is opened to discharge the excess water inside the basin. A total of 2,500 adobe blocks can be produced from one basin.

MouldingWooden moulds of 12 x 9 x 27cm and 12 x 12 x 12cm size are

used (Figure 6). Inside, the moulds are covered by zinc plates, in order to remove blocks easily, and to achieve a smooth surface. The mould is placed on a floor of cement screed. The earth mortar is mixed thoroughly before filling the mould. There is no compaction procedure; however, the earth is thrown forcibly into the mould.

The excess material on the top of the mould is trimmed and the mould is removed. The blocks are left on the floor for at least two days. After, they are turned on their reverse side and left for one day. Next, they are leaned against each other, as in Figure (7a), for one week. This allows moisture to evaporate homogeneously, preventing shrinkage cracks during drying.

Using this method, two workers can produce 400 adobe blocks in a day, enough for a 10m2 wall. The local climate lets artisans work on adobe production from mid-May to mid-October.

After drying, the adobe blocks are stored under an open shed (Figure 7b). This kind of storage has two advantages: it leaves open space between the blocks, and prevents the corners from breaking.

Wall PlasterThe same earth mortar is used as a wall plaster. For the

plaster, both earth and straw are sieved through a coarse screen of 4mm mesh.

Plaster ApplicationThe adobe wall surface is thoroughly wetted before

applying the undercoat plaster. The surface is scraped and scoured with a stiff brush to remove all loose earth and dust in order to achieve adequate plaster adherence underneath. Mortar is applied by throwing it over the surface of the wall. Then, the surface is scratched with a nail. It is left to dry for approximately one week. For the application of final rendering, first, the working area is sprinkled by water by using plaster brush. Then 1-1.5cm of mortar is applied over the surface by trowel, and leveled to achieve a smooth surface. The total thickness of the plaster is approximately 3cm. The process is finished by applying transparent colorless silicon-based water repellents that allows the walls breathe as well. Paint is not used at the site in order not to conceal the identity of the adobe. The maintenance of the finishing coat is required every year where the walls are directly exposed to rain; otherwise, no specific failure is detected. Thus, from previous research literature, to protect the blocks from erosion by acting as water proofers, one of several surface applications is recommended:

• A clear silicone coating (particularly for rainy areas); • A lime wash that is renewed every year, • A sodium silicate coating, commonly known as water

glass but this usually fails a short time after it has been applied by penetrating and then causing the earth to flake away,

• Various types of oil (Williams, Eastwick & Easwick, 1950),

10

(a) (b)

Figure 7 Drying of the adobe.

29

Figure 6: Adobe moulds.

12

27

12

9

1212

12

Figure 6: Adobe moulds.

Figures 7 a & b: Drying of the adobe.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

Architectural Science Review Volume 51, Number 4, December 2008354

• Three coats of exterior cement wash (McClintock, 1989).

In Another one of the studies, fly ash, powdered brick, hydrated lime and water were mixed to develop a pozzolonic plaster for use in conservation of earthen walls against destructive action of rain (Degirmenci & Baradan, 2005).

Experimental ProcedureTests were performed on the adobe blocks used in the

construction. The measured properties of the blocks are shrinkage, density, unit weight (specific density), water dispersion, static modulus of elasticity, flexural strength, and compressive strength. All these properties are considered important to evaluate the suitability of blocks for use. Earth walls are normally considered to be incombustible and resistance to fire is likely to be sufficient for dwelling houses, so, no tests were done on this subject.

Eleven blocks were tested. Specimens 2, 3, 4, and 6 were reserved for the water absorption experiments. Specific density was found only on Specimen 10. For the mechanical properties, four specimens were used.

A non-destructive digital tester ‘WTW DIGIEG-C2’ determined the modulus of elasticity. The mechanical tests were performed with a universal testing machine, ‘MFL’, with a capacity of 100 kN. Flexural testing was performed using a one point loading arrangement, with support spacing of 100mm.

Results and DiscussionLinear Shrinkage and Density

The average linear drying shrinkage of all 11 specimens is 5.22% of the dimensions right after the bricks were removed from the mould and 1.92% of the dimensions after initial drying. In order to find the dry dimensions bricks were kept in the etuve at 105±5 ºC for 24 hours, then replaced into the desiccator until the equilibrium moisture content is reached prior to testing. Because the blocks are moulded and dried thoroughly before construction, drying shrinkage of adobe

blocks may not have much negative impact as in Pise (rammed earth) or Cob construction. Thus, the drying shrinkage of adobe can be as high as 5-6% (Kömürcüoğlu, 1962). High values of shrinkage indicate high water content, typically because a high proportion of clay is used in the mixture. Excessive shrinking also permits cracking during the drying process. Hence, the block can be affected by ambient conditions, and may have relatively low mechanical strength. It is advised to reduce drying shrinkage by changing the binder/sand proportion of the mixture (King, 1996).

Figure 8 shows that the measured density of all specimens is approximately the same.

Typical densities for adobe are 1.20 gr/cm3 for adobe with straw, 1.55 gr/cm3 for gypsum- stabilized adobe, and 1.70 gr/cm3 for cement-stabilized adobe (Yücesoy, 1984). The specific density (δ) of the adobe relates to its average porosity (p). The pore characteristics (size, open or closed surface structure, interrelation, and the pore distribution) affect properties such as water absorption and flexural and compressive strength. The average porosity can be determined from the formula 1-c=p, where the compaction, c, is defined as Δ/δ. Specimen 10 has a specific density 2.51 gr/cm3 and compaction 1.68/2.51=0.67. Thus, this specimen has average porosity 0.33. Because porosity is deduced from the density, it is expected to have negligible variation across all the specimens.

Water Absorption The water absorption capacity and saturation coefficient of

a material relate to its freeze/thaw resistance and mechanical strength. Water absorption tests were performed on Specimens 2, 3, 4, and 6. However, since they were dispersed in the water, it was impossible to achieve any result. Following Turkish Standard 2514 (Turkish Standard Institution, 1997), a water dispersion experiment was applied to Specimen 1. Half of the specimen was immersed in water. The dispersion time was measured. In the first 20 minutes, the parts seen from the outside began to disperse. Fifty minutes later the corner of the specimen collapsed. The relevant standard specifies

2

Tables

Table1.Test results of density and drying shrinkage.

SpecimenNo.

DryingShrinkage(after removedfrom the mould)(%)

Density(gr/cm3)

SpecimenNo.

DryingShrinkage(after removedfrom the mould)(%)

Density(gr/cm3)

1 4.07 1.57 7 6.30 1.71 2 3.70 1.67 8 5.56 1.71 3 5.56 1.68 9 5.93 1.73 4 5.56 1.67 10 7.04 1.73 5 5.56 1.73 11 4.44 1.59 6 3.70 1.68 Average 5.22 1.68 Specific Gravity (Specimen No. 10)

2.51

Porosity (average) 0.33

Std. Dev. 1.09 0.054

Table 1: Test results of density and drying shrinkage.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

355Leyla Tanaçan Adobe Construction

a minimum of 45 minutes for the water dispersion of good quality adobe. The capillary water absorption was totally completed (the time in which the adobe became thoroughly wet) in 110 minutes. These observations show that material has open, fine and interrelated pore structure, which enables capillary water diffusion in the material.

Sound VelocityAs can be seen from Table 2, the average sound velocity

is 1082 m/sec. The variations in this value give clues to the pore distribution of the adobe. The velocity of sound has a strong relation with both the unit weight (Δ) and porosity (p). However, while unit weight and porosity have deviations of only ±3-4% across the specimens, sound velocity has a deviation of 18.5%. This shows that although the specimens have similar characteristics related to their mixture, weight, and porosity, there are differences between them in terms of their pore size and their pore distribution.

The sound velocity of Specimen 10 is the highest value. As seen from test results, although it has approximately the same unit weight with the other specimens, the drying shrinkage of the same specimen also gains the highest value (7.04%). This indicates that the proportion of clay in the mixture is greater than the proportion of sand (both have similar specific densities). Clay is a binding agent and has fine grains, which

can enable more homogeneous and finer pore size distributions. On the other hand, although the specimen has the highest drying shrinkage, it has the highest sound velocity (1296.5 m/sec), which means that there is no interstitial problem in the body that may affect the mechanical properties.

Although Specimen 10 has the highest sound velocity, testing the specific density only on Specimen 10 is considered to be sufficient, because sand and clay used in the mixture have almost the same specific density (2,51 gr/cm3).

Modulus of ElasticityThe modulus of elasticity (MoE) gives important information

about the mechanical strength and elastic deformation of a load-bearing material. The modulus of elasticity of Specimens 8, 9, and 10 are very close to each other (Figure 9). This value is 20-30 kN/mm2 for normal concrete, 5-10 kN/mm2 for gypsum mortar, 3-5 kN/mm2 for load bearing clay brick walls, and 4-10 kN/mm2 for stone load-bearing masonry walls. As a general evaluation, the average value of the adobes (2.11 kN/mm2) is approximately the half of the value of clay brick masonry walls (Kocataşkın, 1976).

Flexural StrengthMechanical test results for Specimen 5 are the lowest

compared to the other specimens (Figure 10). In flexural strength, the average value of the other three specimens is 0.69

23

Table 2: Test results of the mechanical tests.

Specimen

No.

Drying

Shrinkage

(after

initial

drying)

(%)

Density

(Δ)

gr/cm3

Sound

Velocity

(m/sn)

Young’s

Modulus

of

Elasticity

(kN/mm2)

Flexural

Strength

(N/mm2)

Compressive

Strength

(N/mm2)

5 1.92 1.73 813.40 1.17 0.29 1.48 1.17

8 1.92 1.71 1123.35 2.20 0.63 1.68 1.85

9 2.31 1.73 1094.83 2.11 0.78 1.83 1.59

10 3.46 1.73 1296.48 2.96 0.68 2.54 2.49

Average 1082.01 2.11 0.59 1.83

Std. Dev. 200.02 0.73 0.21 0.48

31

Figure 8: Test results of specific gravity and density.

0,00

0,25

0,50

0,75

1,00

1,25

1,50

1,75

2,00

2,25

2,50

2,75

1 2 3 4 5 6 7 8 9 10 11

Specimen Number

Density (gr/cm3) Specific density (gr/cm3)

Table 2: Test results of the mechanical tests.

Figure 8: Test results of specific gravity and density.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

Architectural Science Review Volume 51, Number 4, December 2008356

N/mm2 and greater than that of Specimen 5 in the proportion of 17%. Although this value decreases the average value of the flexural strength, it is included in the evaluation as a safety tolerance. The flexural strength of a structural material, like adobe, is not as important as the compressive strength, but it can give an idea about the strength and behaviour of the material. Here, straw has a considerable importance. It creates a network of omni-directional fibers that improves notably tensile and shearing strengths and helps to reduce shrinkage.

Compressive StrengthAs shown in Figure 10, the compressive strength of the

material is three times greater than its flexural strength. The average compressive strength of eight samples is 1.83 N/mm2, with a maximum of 2.54 N/mm2 and a minimum of 1.17 N/mm2. Figure 11 compares the load-bearing capacity of adobe with that of other building materials (Kocataşkın, 1976).

Turkish Standard 2514 gives the minimum value of compressive strength for adobe as 1.0 N/mm2. As shown in Figure 8, adobe has the lowest value among the alternative masonry materials (of course, none has the compressive strength of concrete). On the other hand, the thickness of the

adobe wall is 40cm, considerably greater than the thickness of a typical clay brick wall, which is approximately 19cm. Hence, the difference in compressive strength may be acceptable.

When the test results of compressive strength are compared with the test results of flexural strength, it is seen that the compressive strength of Specimen 10, which has the highest sound velocity, has the highest compressive strength, as opposed to the Specimen 9, which has the highest flexural strength. No. 10 has also the highest density. This can be explained by considering the straw additive. Straw functions as a fibre reinforcement, and is dispersed in the mixture in various densities and proportions. For composites like adobe, the homogeneous dispersion of the fibre should be considered particularly important. Especially above a critical value of fibre volume fraction, any gains in efficiency can be lost due to coagulation. This also has negative impacts on compressive strength. On the other hand, the presence of fibers in mud bricks provides flexibility to the structures thus enhancing their earthquake resistance. Due to its fibers, these bricks can store more elastic energy, are strong enough, ductile and resistant against earthquakes (Binici, Aksogan & Shah 2005).

34

Figure 11: Compressive Strength of different materials.

16,00

1,50

3,00

1,001,83

30,00

8,00 8,50

15,00

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

Concrete Gypsum

Mortar

Clay Brick

Wall

Stone Wall Adobe

Com

pres

sive

Str

engt

h(N

/mm

2)

Compressive Strength (N/mm2)

33

Figure 10: The variation of compressive and flexural strength among the specimens.

1,48

1,681,83

2,54

1,17

1,85

1,59

2,49

0,29

0,630,78

0,68

0,00

0,50

1,00

1,50

2,00

2,50

3,00

5 8 9 10

Specimen Number

Com

pre

ssiv

e an

d F

lexura

l S

tren

gth

(N

/mm

2)

Compressive Strength (N/mm2) Flexural Strength (N/mm2)

32

1,17

2,2 2,11

2,96

0,00

0,50

1,00

1,50

2,00

2,50

3,00

3,50

5 8 9 10Specimen Number

Mo

du

lus

of

Ela

stic

ity

(kN

/mm

2)

Figure 9: Test results of modulus of elasticity.Figure 9: Test results of modulus of elasticity. Figure 10: The variation of compressive and flexural strength

among the specimens.

Figure 11: Compressive Strength of different materials.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

357Leyla Tanaçan Adobe Construction

Building AcousticsAdobe, with its structure and surface texture, has good

properties in terms of sound absorption compared to other alternative materials. In the case of sound transmission loss (R), it is directly proportional with the surface density (m) (kg/m2) of the building elements. When the surface density of the partition is increased, R value is also increased as shown in Eq. 1:

15

which has the highest flexural strength. No. 10 has also the highest density. This can be

explained by considering the straw additive. Straw functions as a fibre reinforcement, and is

dispersed in the mixture in various densities and proportions. For composites like adobe, the

homogeneous dispersion of the fibre should be considered particularly important. Especially

above a critical value of fibre volume fraction, any gains in efficiency can be lost due to

coagulation. This also has negative impacts on compressive strength. On the other hand, the

presence of fibers in mud bricks provides flexibility to the structures thus enhancing their

earthquake resistance. Due to its fibers, these bricks can store more elastic energy, are strong

enough, ductile and resistant against earthquakes (Binici, Aksogan & Shah 2005).

Building Acoustics

Adobe, with its structure and surface texture, has good properties in terms of sound

absorption compared to other alternative materials. In the case of sound transmission loss

(R), it is directly proportional with the surface density (m) (kg/m2) of the building elements.

When the surface density of the partition is increased, R value is also increased as shown in

Eq. 1:

The density of the adobe is 1680 kg/m3. For sound at a frequency of 1000 Hz, the R

value for the partition walls of the stable and restaurant, which are 46cm thick, can be

calculated as 54,5 dB. For the hotel rooms, which have exterior walls of 33cm and partition

walls of 18cm, R values of 53 dB and 48 dB can be achieved respectively. According to

Turkish Standard 2381 (TSE, 1985), sound transmission loss of 55 dB is needed for sound at

a frequency of 1000 Hz. As a result, the partition walls of the hotel are not sufficient for

reducing sound transmission.

)(10log4.151

dBmR

n

i

i+= !

= (1)

The density of the adobe is 1680 kg/m3. For sound at a frequency of 1000 Hz, the R value for the partition walls of the stable and restaurant, which are 46cm thick, can be calculated as 54,5 dB. For the hotel rooms, which have exterior walls of 33cm and partition walls of 18cm, R values of 53 dB and 48 dB can be achieved respectively. According to Turkish Standard 2381 (TSE, 1985), sound transmission loss of 55 dB is needed for sound at a frequency of 1000 Hz. As a result, the partition walls of the hotel are not sufficient for reducing sound transmission.

Accordingly, the owner of the hotel noted some complaints during the interview.

Thermal EvaluationThe thermal conductivity (W/mK) of a material is related

to the porosity and density of a material. This value is 0.80 W/mK for lightweight concrete, 2.04 W/mK for normal concrete, 0.79 for masonry clay brick, 2.33 W/mK for stone and 0.60-0.70 W/mK for adobe that is stabilized with cement. The densities of same materials are 0.80, 2.40, 1.80, 2.70, 1.7 gr/cm3 respectively (Yücesoy, 1984). (Kocataşkın, 1976).This value is almost equal to the properties of the adobe in this study.

Due to the thickness of the adobe walls, their thermal inertia is high (Parra-Saldivar & Batty 2006) making them suitable for arid (hot and cold) climates. On the other hand, according to Turkish Standard TS-825 (TSE, 2000), it is recommended that for the buildings located in the II thermal region where

Istanbul is, the maximum U value of the walls should be less than 0.60 W/m2K. Here with this material, the U value of 1.06 W/m2K is achieved for 46cm wall thickness and 1.38 W/m2K is achieved for the 33cm wall thickness. They are both higher than the required value. This negative side of the material should be considered and necessary precautions should be taken. The owner of the club also complained about the thermal behaviour of the adobe, especially used in the exterior walls of the hotel. For this reason, he has applied wooden horizontal weatherboarding to the exterior north facing walls (Figure 12).

The club owner said if given a second chance, he would again build using adobe, but would utilize it as an infill material rather than as a load-bearing material. Therefore, he could produce the material lighter than the material in use and with improved thermal properties.

ConclusionsInitial drying shrinkage of the adobe is on the upper limits

(5.22%). However, there is no evidence of building hazards or failures related to the excess shrinkage that may affect the performance of the buildings. This can be improved by changing the binder/sand ratio of the mixture.

Adobe can be considered as in the range of good quality in terms of water dispersion. Nevertheless, since adobe can accumulate considerable quantities of moisture, either because of rain penetration or vapour condensation, during its construction and its service life, it should be protected from water. In the case of this study, the walls are protected from rain by wide eaves and from ground water by the damp-proof course. Certain precautions were taken against erosion from driven rain during the design stage.

Only where the eaves had to be made narrow, are stains observed due to the washing effect of rainwater (Figure 13). In order to determine the resistance of the material against splashing water, tests must be done.

The properties of density, specific density, and porosity/compaction of the adobe is determined to be approximately the same for all the specimens, but the pore size and their

35

Figure 12: Weatherboarding of the north face.Figure 12: Weatherboarding of the north face.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

Architectural Science Review Volume 51, Number 4, December 2008358

distribution varies from one specimen to another. This structure affects the mechanical properties like the modulus of elasticity, and the flexural and compressive strength of the material.

Particular attention must be paid to the dispersion of fibre reinforcement of straw, homogeneously in the mixture in order to achieve the same quality for every block produced from the same batch. This can be deduced from the relationship between flexural and compressive strength. The compressive strength of the material is quite higher than the minimum value recommended in TS 2514.

Adobe performs well in terms of acoustical properties. However, in the hotel, where partition walls were built to only 18cm, it is not used in an efficient way. With this kind of adobe, a minimum thickness of 33cm is advised.

The density of the adobe is in the range of the values given in literature; however, its thermal performance (U-value) as a wall material is too high for use in Istanbul. So, efforts must be made to design the building system for greater insulation capacity, in order not to sacrifice energy performance.

As a general conclusion, the adobe used as a load-bearing wall material in these buildings has sufficient mechanical properties, even though it was produced locally. In terms of its physical properties, it performs well. Since construction details were attended to properly, it has been used since 1998 without requiring any maintenance or repair. However, in terms of its thermal behaviour it needs to be evaluated again for the weather conditions of Istanbul.

AcknowledgementThe author gratefully acknowledges the assistance of İbrahim

Öztürk in testing the materials (Building Materials Laboratory, Faculty of Architecture, Istanbul Technical University), Sadık Boztimur (adobe artisan) and Hakan Kök, the owner of the Country Club.

ReferencesBinici, H., Aksogan O., & Shah, T. (2005). Investigation of the fibre

reinforced mud bricks as a building material. Construction and Building Materials, 19, 313-318.

Carmen Jimenez Delgado, M., & Guerrero, I.C. (2006). Earth building in Spain. Construction and Building Materials, 20, 679-690.

Degirmenci, N., & Baradan, B. (2005). Chemical resistance of pozzolonic plaster for earthen walls. Construction and Building Materials, 19, 536-542.

Fathy, H. (1973). Architecture for the Poor. Chicago: University of Chicago Press.

Guillard H., Joffroy, T., & Odul, P. (1995). Earth construction. In Compressed Earth Blocks. Volume II: Manual of Design and Construction. Braunschweig, Germany: Friedr Vieweg & Sohn Verlagsgesellschaft mbH. Also in Sustainable Building Technologies. Gallen, Switzerland: Library of SKAT-Publications, Skat 2001 [CD-ROM].

Guillaud H., & Houben, H. (2001). Earthen architecture: Materials, techniques, and knowledge at the service of new architectural applications. In Proceedings of the 1st International Conference on Ecological Building Structure [CD-ROM]. San Rafael, CA: Ecological Building Network.

Isik, B., & Tulbentci, T. (2008). Sustainable housing in island conditions using Alker-gypsum-stabilized earth: A case study from northern Cyprus. Building and Environment, 43, 1426-1432.

Kafesçioğlu, R., & Gürdal, E. (1985). Alker Çağdaş Yapı Malzemesi (Alker Contemporary Building Materials). Istanbul: Seyhan Press.

King, B. (1996). Buildings of Earth and Straw: Structural Design for Rammed Earth and Straw Bale Architecture. Sausalito, CA: Ecological Design Press.

Kocataşkın, F. (1976). Yapı Mühendislerine Malzeme Bilimi (Materials Science for Structural Engineers). Istanbul: Istanbul Technical University Press.

Kömürcüoğlu, E. (1962). Yapı Malzemesi Olarak Kerpiç ve Kerpiç İnşaat Sistemleri (Adobe as a Building Material and Adobe Construction Systems). Istanbul: Istanbul Technical University Press.

McClintock, M. (1989). Alternative House Building. New York: Sterling.

Millogo, Y., Hajjaji, M., & Ouedraogo, R. (2008). Microstructure and physical properties of lime-clayey adobe bricks. Construction and Building Materials, 22, 2386-2392.

Moquin, M. (2000). Adobe. In E. Lynne & C. Adams (Eds.), Alternative Construction: Contemporary Natural Building Methods. Toronto: Wiley.

Naumann, R. (1975). Eski Anadolu Mimarlığı (Ancient Anatolian Architecture). Ankara: Turkish History Institution Press.

36

Figure 13: Water stain on surface of the wall.Figure 13: Water stain on surface of the wall.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14

359Leyla Tanaçan Adobe Construction

Parra-Saldivar, M.L., & Batty, W. (2006). Thermal behaviour of adobe construction. Building and Environment, 41, 1892-1904.

Pineda-Pinon, J., Vega-Duran, J.T., Manzano Ramirez, A., Perez-Robles, J.F., Balmori-Ramirez, H., & Hernandez-Landaverde, M.A. (2007). Enhancement of mechanical and hydrophobic properties of adobes for building industry by the addition of polymeric agents. Building and Environment, 42, 877-883.

Turkish Standard Institution (TSE) (1985). The Evaluation of Sound Isolation in Residential Buildings: TS 2381. Ankara, Turkey: Turkish Standard Institution.

Turkish Standard Institution (TSE) (1997). Adobe Blocks and Production Methods: TS 2514. Ankara, Turkey: Turkish Standard Institution.

Turkish Standard Institution (TSE) (2000), Thermal Insulation Requirements for Buildings: TS 825. Ankara, Turkey: Turkish Standard Institution.

Williams, C.E., Eastwick, J.F., & Easwick, E.F. (1950). Building in Cob, Pise, and Stabilized Earth. London: Country Life Limited.

Yücesoy, L. (1984). Yapıda isı ve nem etkisi (Thermal and moisture effects in buildings). Unpublished report, Department of Architecture, Istanbul Technical University, Ankara.

Dow

nloa

ded

by [

Yor

k U

nive

rsity

Lib

rari

es]

at 1

4:23

23

Sept

embe

r 20

14