ALÇI VE KİREÇ KATKISIYLA KERPİÇ YAPILARIN PERFORMANSINI YÜKSELTMEK

Studies have been carried out to resolve the housing problems of poor people all around the world. Low-priced and fast construction systems, which can be built with local materials, have always been required. Adobe buildings have the capacity to meet this need and are the most suitable systems fulfilling the housing needs of almost 50% of the world’s population (Houben, 1994). Interest in adobe buildings, first built in Mesopotamia c. 7000 BCE, has recently increased due to needs for energy conservation, reduced pollution, environmental concerns and increased standards of living. Thus, studies and researchers have gained new perspectives. Adobe buildings have been reevaluated in numerous studies under current conditions and compared with modern materials. Not only are adobe buildings environmentally friendly, but they are also advantageous regarding production and service costs compared to buildings made from burned bricks (CID, 1993, Riza et al. 2010). Adobe constructions, besides their superiority, are criticized as needing repair (Kerali, 2001), having thick and heavy walls, relatively low compressive and shear strengths and in particular the possibility of becoming damaged under earthquake effects (Ural et al., 2011, Maheri et al., 2005). Damages in adobe buildings are associated with material quality, ground motion acceleration, wall slenderness, structural design and geometry which have an effect on building performance (Bariola and Sozen, 1990, Samali et al., 2011). In particular, it is recommended to take precautions to improve the performance of adobe buildings under earthquake risk. Using natural fibers (Vargas et al., 1986, Vega et al. 2011, Lertwattanaruk and Choksiriwanna, 2011), wooden reinforcements or welded steel reinforcements improves the strength of adobe materials and the performance of a building which presents nonlinear behavior. Stabilizing the earth with some additives in adobe manufacture, as well as the use of fibers and reinforcements, presents positive effects on building performance depending on better material performance. Many stabilization methods have been practiced from past to present in order to improve material performance. The most significant stabilization method is the addition of lime (Khattab et. al., 2007, Millogo et. al., 2008). Lime reacts with clay and forms C-S-H and calcite crystals as it becomes carbonated in stabilizing with lime (Khattab et. al. 2007, Millogo et. al. 2008). Stabilization with gypsum is also studied (Ahmed and Ugai, 2011). Studies on earth construction materials generally have focused on properties such as compressive strength, water resistance and thermal conductivity. It was reported that the compressive strength of current earth construction buildings varied between 0.5 and 3.0 MPa (Silveira, 2012, Vargas et. al, 1986). In 1980 at the laboratory of Istanbul Technical University, Faculty of Architecture, promising results were obtained in a research project focusing on earth constructions in order to improve their durability and strength (Kafesçioğlu, 1980). This paper aims to evaluate the performance of existing buildings built in light of research projects since 1980, by using advanced mechanical, chemical and microstructural analysis techniques. Construction earth, where its structural and chemical compositions have been modified by adding gypsum and lime, has been transformed into a new material with improved physical and mechanical properties. Properties, benefits and applications of this wall material, called Alker, have been summarized in this paper. Like other construction earths stabilized with additives, texture and structure of the product called Alker has been changed becoming an earthbased wall material with improved physical and mechanical properties. The material consists of 8-10% gypsum, 2.5 – 5% lime and 15 – 20% water (dry weight) which were added to construction earth with improved granulometric structure (Kafesçioğlu, 1980). Given mix ratios are by weight of dry earth under laboratory conditions. Converting these ratios into a volumetric scale at construction sites provides ease of application. Gypsum and lime are added to the mixture and it completes setting within 20 minutes, giving rigidity to the material which allows its shape to be kept and preventing clay shrinkage. The blocks can then be demolded after 20 minutes has passed, gaining their rigidity and strength by reactions of lime. other similar materials. Due to the early setting time of gypsum, deformation and crack risk to the structure during the drying period is prevented. A new water insoluble chemical formation is created by adding 2.5-5% lime. The product does not become dispersed as plain samples even though it stays in the water for a long period of time. The satisfactory rigidity created by gypsum in the first stage ensures shape stability of the blocks as the new formations continue developing in the structure. The production process is very easy and energy consumption in buildings made with this material are minimal. While the buildings are healthy, it also creates a healthy environment for users.