Temellerde su yalıtımı
Waterproofing of foundations
Yazar: AYŞE NİL ŞAHAL
Danışman: PROF. DR. İMER SUNGUROĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü
Derece: Yüksek Lisans, 1992
Konu: Mimarlık = Architecture
Dizin: Binalar = Buildings ; Su yalıtımı = Waterproofing insulation ; Yapı sistemleri = Structure systems ; Zemin suyu = Soil water

Özet:
Ülkemizde, temellerde su yalıtımı ile ilgili yapılan çalışmalarda her zaman başarılı sonuçlar alınamamakta ve bu sonuçlar maddi ve manevi birçok zararlara neden olmak tadır. Bu önemli nedenden yola çıkarak yapılan bu çalışmada, binaların temellerinde suyun olumsuz etkilerine karşı geçirimsizlik. işlevini -yerine getiren ve uzun ömürlü yalıtım çalışmalarını gerçekleştirecek adımlar sırasıyla ele alınmıştır. Sözkonusu yaklaşımda, binaların yer aldıkları zeminlerde mevcut veya oluşabilecek çeşitli zemin suları tanım lanmış ve bu suların temellere nasıl etki ettikleri açıklanmıştır. Zeminde suların oluşmalarına neden olan zemin cinsleri ve arazi şekilleri tanımlanmıştır. Bütün bu faktörlere bağlı olarak, bina temellerinde suya karşı alinması gereken "pasif yalıtım önlemi" açıklanmıştır. Daha sonra, temellerde çeşitli zemin suların olumsuz etkilerine karşı yapılması gereken yalıtımın esasını teşkil eden tam geçirimsiz tabakanın oluşturulmasında kullanılan çeşitli yalıtım sistemleri ve malzemeleri, diğer bir deyişle "aktif yalıtım önlemi" ele alınmıştır. Bu konudan sonra, çeşitli zemin sularına göre binanın temellerinin hangi yapı sistemi ile oluşturulması gerektiği açıklanmıştır. Bununla beraber çeşitli yapı sistemlerin de, aktif yalıtım önleminin gerek zemin sularına bağlı olarak oluşturulacağı yalıtım sistemi ve malzemesi gerekse bina konumlarına bağlı olarak yeri belirlenmiştir. Son olarak, başarılı bir yalıtım uygulaması için dikkat edilmesi gereken hususlar ele alınmıştır. vııı

Abstract:
In our country, waterproofing precautions aren't taken in most of the building foundations. Despite of this fact, there are some buildings in which waterproofing precautions have been taken but nearly all of them have lost their functions because of the mistakes which had been made during the applications. Unfortunately, there are only a few successful examples of waterproofing of foundations. The reasons are as follows:. - The decisions that must be given concerning waterproofing of foundations aren't being taken into consideration in the preliminary project stage of the building. - Architects and engineers don't give sufficient importance to the subject of "waterproofing of foundations" and besides they don't have enough knowledge about waterproofing precautions. - The regulations which define the right materials and their applications in waterproofing of foundations aren't suitable anymore for today's conditions and technology. - One of the most important factors is the ignorance of public about waterproofing of foundations. Usually, users don't consider this matter when evaluating buildings. Therefore, they don't demand from architects and engineers to take waterproofing precautions in building foundations. Because of the reasons explained above, when water - proofing precautions aren't taken and when they don't give satisfactory results, groundwater affects through foundations in several ways. Groundwater penetrates foundations, walls and floors of basement. As a result, capillary water exists in the building elements mentioned above. Capillary water causes various forms of damage such as loosening or delamination of the floor and wall xxcoverings. Efflourence and moulding are other kinds of damage which occur on the internal surfaces of walls caused by the effect of capillary water. The inner spaces which are surrounded by these damaged walls are not suitable for users.Briefly, damages caused by capillary water adversely affects the use of the building and causes discomfort to the users. Another factor which must be taken into consideration is the relationship between dampness and heat. Because of several reasons, capillary water within building elements vapo.urizes and as a result of this the thermal resistances of insulating materials within walls and floors decrease. Thus, the heat conservation of the inner spaces which are surrounded by these walls and floors become inefficient and heating costs inrease. At the first glance, when sufficient importance isn't given to the subject of waterproofing of foundations, it may seem that the construction cost of the building would be lower compared with the construction cost when expenses have been made for waterproofing of foundations. As a matter of fact, the expenses which will be made for the maintenance of the building and repair of the damages caused by the absence of waterproofing of foundations or the mistakes made during waterproofing applications cost much more than the expenses that would be made for waterproofing which add only a small percentange to the construction cost. Unfortunately, the scope of these additional expenses isn't realized until it is too late. Because of the reasons explained above, the matter of waterproofing of foundations is very important. Therefore, waterproofing precautions must be taken in the foundations of every building. In this study, in order to ensure a successfull examination concerning waterproofing of foundations, each decisions that must be made, is explained step by step. At the first stage, the architect must determine the soil type and the ground form of the building's site. The ground form can be sloping or flat. The soil type can be permeable, impermeable or a combination of these types. Depending on these factors, the architect must find out about the groundwater types which already exist or are likely to occur within the ground. The types of ground water are leakage water, ground moisture and subterrainean water. Depending on the determination of xthese factors, the architect must make clear decisions about the waterproofing of the foundations of the building. There are two kinds of waterproofing precautions. The first one is "passive" and the other is "active". Passive waterproofing precaution is laying a drainage system around the foundation base of the building in order to prevent the accumulation of leakage water. When subterrainean water exist in the ground, the drainage system must be laid under the foundation base in order to keep the excavation dry. Active waterproofing precaution is. forming an impermeable layer which provides a continous barrier against groudwater. At the second stage, according to the type of the groundwater determined previously, the architect must decide on the type of the building system. Accordingly, decisions must be taken on the passive waterproofing precaution. At the third stage, according to the type of the groundwater, the architect must determine the type of the waterproofing system which will be used and the materials which will be applied in order to form the impermeable layer. At the last stage, the location of the impermeable layer must be decided on according to the location of the building which may be attached or detached and with or without basement. Depending on the ground form and the soil type, if leakage water and ground moisture exist in the ground, the construction system of the building must be either loadbearing or frame construction. If needed, the drainage system can be laid around the foundation base. The followings are the types of the waterproofing systems used and the materials applied to form the impermeable layer. - Rigid waterproofing system: Waterproof, screed Waterproof plaster Waterproof concrete - Semi-elastic waterproofing system: Mastic asphalt Hot-mixed bitumen mortar XI- Elastic waterproofing system: Asphalt based cement Oxidised asphalt Bitumen asphalt solution Bitumen asphalt emulsion. In a loadearing construction whether it is attached or detached, a water-stop must be placed between the ring beam and the concrete base. Waterproof screed must be applied onto the ring beam and the concrete base leaving the joint empty. Later on, the joint must be filled with mastic asphalt. The waterproof screed must be at least 30 cm. high above the natural ground level. If the building has a basement, apart from these waterproofing precautions mentioned above, precautions on the walls of the basement must be taken against groundwater. The impermeable layer must he applied onto the external surfaces of the walls if it is a detached building or the layer must be applied onto the internal surfaces of the walls if the building is attached. Besides waterproof plaster, the other waterproof materials mentioned before can be applied onto a sub-coat and there must be a protective coating between the layer and the ground. The impermeable layer applied onto the walls must adhere to the waterproof screed and be at least 30 cm high above the natural ground level. The vertical impermeable layer must also adhere to the waterproof screed which is located on the top of the walls. Because of any reason, if waterproofing precautions has to be taken at the ground floor/ the groundfloor slab must be made of waterproof concrete. The impermeable layer must be applied onto the internal or external surfaces of the walls depending on the building's location. The layer must be one storey high and be adhered to the waterproof screed applied on the top of the walls of the groundfloor. In a frame construction, whether it is attached or detached, the footings and the tie beams must be made of waterproof concrete. A water-stop must be placed between the tie beams and the concrete base. Waterproof screed must be applied onto the concrete base and the tie beams leaving a joint in between. The joint must be filled with mastic asphalt. The waterproof screed must be at least 30 cm high above the natural ground level. If the building has a basement, the precautions mentioned above must be taken. But at this stage, one of the most important matters is that the walls of the basement must be planned as concrete walls. Thus the XIIcolumns, concrete walls and the footing of the concrete walls can be made of waterproof concrete at least 30 cm high above the natural ground level. Depending on the ground form and the soil type, if subterrainean water exists in the ground, the main structure of the building can only be planned in one structural system. The walls must be reinforced concrete and the foundations must be raft. The drainage system must be laid under the foundation base. Elastic waterproofing system is used in order to form the impermeable layer. The waterproof materials that can be applied are oxidised and modified bitumen membranes. There are two kinds of waterproofing precautions when the building's foundations are under the effect of hydrostatic pressure of the subterrainean water. One of them is "external tanking" and the other is "internal tanking". External tanking system is used when the building is detached and internal tanking system is used when the building is attached. In an external tanking system, the waterproof concrete base is formed on the ground which has been previously improved. The required number of membranes are placed onto the concrete base forming the horizontal impermeable layer. Afterwards, protective waterproof concrete is placed onto the horizontal impermeable layer. Then the main structure of the building is built. The required number of membranes are applied onto the surfaces of the reinforced concrete walls forming the vertical impermeable layer.. The height of the vertical layer must be at least 50 cm. above the subterrainean water table. Lastly, a support wall is built between the vertical impermeable layer and the ground. In the internal tanking system, a waterproof concrete box is formed on the improved ground where the foundation base will be built. The waterproof concrete base and the waterproof support walls are the vertical and horizontal elements of the waterproof concrete box. The required number of membranes are applied onto the concrete base and the support walls forming the vertical and horizontal impermeable layers. The height of the vertical impermeable layer, must be at least 50 cm. high above the subterrainean water table. After the protective waterproof concrete is placed onto the vertical impermeable layer, the main structure of the building is built. Briefly, the aim of waterproofing foundations is to take precautions against groundwater penetration of the building and therefore to protect the health of the users and the buildings* fabric and to reduce the maintance, repair and heating costs. xiii