Adobe is a building material obtained by adding straw or reed type plants into clay and suitable soil, kneading with water, then shaping by pouring into moulds and drying in the open air.
It is used as a carrier, filling element and coating material in buildings. The fact that the raw material of adobe is soil and water has made it preferred from ancient times to the present day. Adobe was widely used until the 19th century, but then its use decreased with the emergence and development of industrial products such as brick, reinforced concrete and steel. Today, it is stated that 30% of the world population still lives in adobe structures. Proximity to raw materials, easy processability, low cost and environmental friendliness are the main reasons for this situation.
Anatolia and its surroundings, together with Mesopotamia, Iran and the Mediterranean basin to which it is connected, is a region where early mudbrick finds, structures and settlement areas are sheltered and preserved to a certain extent. Çatalhöyük (Konya), Aşıklı Höyük (Aksaray), Alacahöyük (Çorum), Hattusa Castle (Çorum), Sargon's Palace (Malatya) and Harran Kümbet Houses (Şanlıurfa) are examples of mudbrick buildings in our country. Çatalhöyük and Hattuşaş are also included in the UNESCO World Heritage List as the common cultural heritage of humanity. The list also includes settlements with adobe architecture from different parts of the world. Bem (Iran), Genne and Timbuktu (Mali), Shibam and San'a (Yemen) are among the cities that stand out with their unique adobe architecture.
Adobe buildings have different construction techniques according to the geography. In the central and eastern parts of Anatolia, which have an arid climate and a low proportion of trees, masonry mudbrick is used; in the northern, western and southern parts of Anatolia, which have a mild or rainy climate and where forested areas are dense, mudbrick infill walls between wooden carcasses are seen. This construction system has been used extensively in both urban and rural housing construction since the late medieval period. From the 17th century onwards, it formed the civil architecture in many regions of Anatolia and the Balkans. There are many examples of traditional houses with timber and adobe construction systems in our country.
Since adobe is a natural material, it is affected by environmental and climatic conditions. It is exposed to the corrosive effects of atmospheric weather conditions such as wind and rain. Different methods have been developed since the Neolithic period to increase the strength of the uncooked earthen material. The oldest and most widespread of these is the addition of straw, reeds, small stones, pottery shards and other organic materials to the mud prepared to be dried in the sun.
With the development of technology and the use of different raw materials, the reinforcement methods of mudbrick have diversified. We can classify them as mechanical, physical and chemical. Mechanical reinforcement includes the selection of the soil and the interventions to be made in block production; physical and chemical reinforcement includes the additives to be added to the mortar. Improving the granulometry of the soil to be used and tightening the mortar by applying pressure during mould casting is mechanical; organic fibrous plant wastes (straw, plant stems, sawdust, etc.), cement, lime, gypsum, gypsum and lime (Alker), pozzolan (pumice, silica fume, tuff, blast furnace slag, fly ash, etc.), wool, bitumen, wool, bitumen, fly ash, etc. ), wool, bitumen, various industrial wastes (resins, electrolytes and cellulose), glass fibre, air entrainment and plastic fibre are both traditional and innovative materials used as additives. The use of these materials together or separately affects the properties of adobe and increases its resistance especially against external factors.
Physical, chemical and mechanical tests are carried out in the laboratory in order to characterise the material and determine the durability properties of adobe. The examinations are divided into two as the selection of the soil to be used in adobe construction and the determination of the properties of the adobe produced. Samples can be created in the laboratory or construction site environment or can be obtained from historical buildings. According to TS 2514 ‘Construction and Use of Adobe Blocks’ standard, standard consistency test, tensile strength test, shrinkage test, muddying test and compressive strength test are carried out for the determination of adobe soil; for adobe, pressure test and disintegration test with water effect are carried out. Although the cancellation is standard, it continues to be used in research. In addition, granulometric (sieve analysis) and hydrometric (sedimentation analysis) analyses are also preferred to determine the grain diameter distribution and silt and clay ratios of the soil to be used. In adobe samples, a wide variety of experiments are carried out in accordance with the data to be obtained and technical possibilities. For physical properties, unit volume weight, occupancy rate, moisture content, shrinkage, capillary water absorption, thermal conductivity coefficient and erosion resistance are determined. For chemical and petrographic properties, water-soluble salts, protein and fat analyses, loss on heating, acid treatment and sieve analyses are carried out and the images of the aggregates and cross sections are examined under stereo and polarising microscope. Compressive strength, flexural strength, modulus of elasticity and diagonal shear strength tests are performed for mechanical properties.
In addition to the researches carried out in the laboratory environment, advanced analysis technologies have started to be preferred in the material characterisation of adobe. XRD (X-Ray Diffraction) for mineralogical analyses, SEM-EDS (Scanning Electron Microscopy-Energy Dispersive Spectroscopy) for micro-structural and chemical analysis and MIP (Mercury Intrusion Porosimetry) for determination of pore size distribution are the advanced analysis methods used.
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