Geçirimli beton yol üstyapısının incelenmesi

Abstract

Ulaştırma türlerinden biri olan karayolu ulaşımının gelişmesiyle karayolunun mekanik ve fiziksel özellikleri önem kazanmıştır. Bu sebebi e, araştırmacılar yol koşullarını en iyi düzeye çıkartmayı amaç edinmiştir. Bu çalışmada yeni bir üstyapı tipi olan geçirimli beton yol üstyapısı altı bölümde incelenmiştir. Bu tip üstyapıların kullanımına ABD ve Avrupa'nın kalkınmış ülkelerinde rastlanmaktadır. Ülkemizde ise, 1991 yılı itibarıyla, geçirimli üstyapılarla ilgili bir araştırma ve uygulama mevcut değildir. Çalışmanın giriş bölümünde modern bir yoldan beklenen özellikler belirtilmiş ve ayrıca, geçirimli üstyapıların dünyadaki uygulama alanlarından söz edilmiştir. Geçirimli üstyapıların tanımı, kullanım çeşitleri, faydaları ve sakıncaları hakkındaki genel bilgiler bölüm II 'de ayrıntılı olarak verilmiştir. Çalışmanın III. bölümünde, geçirimli üstyapıların mekanik ve fiziksel özellikleri ile birlikte hidrolik boyutlandırmadan bahsedilmiştir. Deneysel çalışmaları içeren IV. bölümde, beş karışım seçeneği üzerinde çalışma yapılmıştır. Bu seçeneklerde su-çimento oranı sabit tutularak, farklı boyutlardaki agrega gruplarının ağırlıkça yüzdeleri değiştirilmiştir. Bu beş seçeneği n, boşluk oranı, hidrolik iletkenliği, birim hacim ağırlığı basınç direnci ve eğilme-çekme direnç değerleri ölçülmüştür. V. bölümde deneysel çalışmalardan elde edilen sonuçların karşılaştırması, beş farklı gradasyonun ; boşluk oranı, hidrolik iletkenlik, birim hacim ağırlığı, basınç direnci ve eğilme-çekme direnci üzerindeki etkisi ile yapılmıştır. Bu beş seçeneğin sonuçları kullanılarak hidrolik projelendirme yapılmıştır. Bu tez çalışmasının son bölümünde, konuyla ilgili araştırmacılara, geçirimli beton yol hakkında genel bilgiler ve önerilerde bulunmuştur.

There are many of expectation from the features of a modern updated road surfacing. The features might be classified in three groups, sometimes in contraversary with itself» and difficult to be provided at the same t i me. Related features with the road users. a> Securi ty (Aderance, vi si bi li ty,especi ally during rai ni ng ). b) Comfort (Vibration, noisebeing perceived in the car >. Related features with the adjacent of the road: Traffic noise, water /l i qui ed splash. Related features with the road-builders and Highway operators. Easy construction and maintenance, reasonable cost and resistance against traffic and weather conditions etc. The characteristics of the surface materials and the geometrical features of the surface lining are directly related with those features as groupped above. The road construction (civil) engineers have construed an original solution with the aim of improvement of the features of the surface lining in relation with the road users and adjacent features around the road, especially improvement for rainy weathers and they have developed the type of "porous surface lining and pavement". The porous surface lining with its large/high permeability the percentage allows a temporary storage of the liquid which enters into the lining layer before approaching the drainage system and before seeping in the ground surface of the lining. The study and application of the porous surfacing systems do not exist yet in our country. In order to decrease the effects of such a missing subject and to point out the importance of these type of surfacings. It was aimed to study the features of this concrete Surfacing in this thesis work. Selection criteria of porous concrete road surfacing can be given below. VI The field of application of porous mixes is determined by the advantages and drawbacks observed in their use. There has been wide experience, above all in Europe, of the behaviour of this type of surfacing, acquired mainly in the last decade, in which the use of porous mixes has became widespread. These different experiences coincide when it comes to pointing out the following advantages and drawbacks for these mixes. Advantages The advantages of porous mixes as wearing courses are the results of three particular features; - Their capacity in wet conditions for keeping the pavement surface free of water. - They are a smooth surfacing full of voids, thus- providing an elevated macrotexture. - Their high noise absortion capacity. Each of these features contributes in one degree or other to improve the response of these materials as- wearing courses, with the following advantages having been observed; They considerably reduce the risk of aquaplaning. In wet conditions they reduce the splashing and spraying effect caused by the passing of traffic. They pre%'ent glare. They maintain resistance to skid at high speeds. They reduce noise caused by traffic movement. Drawbacks- Porous mixes, compared with conventional mixes, also have certain drawbacks and limitations which must be evaluated before use. These limitations specifically refer to durability, both physical and functional; their need to be supported by a regular waterproof ed surface; winter maintenance; and finally, their structural capacity. The required/expected features of this modern way of surfacing are described in the introduction section with six chapters and furthermore, the world wide appıl i cations of the porous surfacing has been introduced in this stage. The general informations related with the VII defi nation, types of usage, advantages and drawbacks of these porous surfacings are described in details in section 2. The mechanical and physical features of these porous surfacings are mentioned in the study section 3 with its hydraulic di mensi onings respectively. Study works have been perfomed on the choice of B different mixtures which are contained in the experimental activities section 4. In these alternatives, the weighing percentages of the aggregate groups in different si ses were kept as fixed on water/cement ratio, and the porousity ratio, hydraulic conductivity, unit volume weight, pressure resistance and bendi ng-shri nkage resistange values of those B alternatives have been measures accordingly. The comparisons made on the results obtained in chapter B, the effects of these 5 different gradations have been perfomed on the porosity ratio, hydraulic conductivity, unit volume weight, pressure resistance bendi ng-shri nkage resistance of the B gradations. The hydraulic projection has been constructed by using the results of those B alternatives. In the final section of this thesis work, the related general informations and recommendation on the researchers and porous concrete roads are described as the following. This new application provides an accelarated surface liquid flow during rainy weathers and improves the travel security and the visual conditions on the related road. Beside the water drainage, the most inportant feature of such surfacing with porous structures is to absorb the noise being created by the transport means or cars. The porousity of the mixture ratios to be used on such surfacings layes between £0-27 per cent. As to the Normal type (non-porous) surfacings, since no seapage is desired to the ground layers of the surfacing, the ratio of porousity is kept as minimum as possible. In order to obtain the degree of stability required, the aggregate material to be used must be crushed and edged. The high rate of porousity in the mixture is VIII obtained by keeping the weighing percentage of the large granules in excess to be indicates in the granulometer. -The high porousity rate of surfacing which can be provided by poor compaction may decrease due to additions compaction occured during over-crowded traffic on the road under service. - Since the rate of porousity of the surfacing is effecting the road surface, the macrotexture on the surfacing is notable higher. Since the macrotexture provides higher slippage-abrasion resistance, it decreases the slippage risks of the cars during rainy wheathers. - The high rate of porousity on such surfacings is creating lower mechanical features on the said road. - The mechanical features on the porous surfacings can be improved by adding high dosaged cement and cement add! t i yes. - For application of a porous surfacing, the minumum height of the porous layer can be determined by the raining rate of the area chosen and the maximum water level being occured on the road surface. - A thicker layer can not effect the hydraulic conductivity from the mechanical point of view. However a layer which is lower than the maximum water level is subject to be covered with liquids during raining. -In case the weighing percentage of the aggregate material is increased in the mixture the permeability shall increase as well. But on the other hand, the mechanical feature of the surfacing is considerably effected. - This case have to be taken into consideration during hydraulic and also during mechanical projection. - The permeable structure of the surfacing effects the surface lining against external effects easily. This state shortens the endurance life of the surface lining accordingly. - The dusts which enter into the porous -eel Is of the surface lining decreases its hydraulic conductivity. The pores plugged by dust are to be removed by vacuum-cleaning or pressured water jetting. This state results a difficult and costly maintenance of the permeable surfacing. - If the natural ground surface on which the permeable surfacing is to be placed on the construction costs shall decrease appropriately. Because there is need for a film layer and drainage channels respectively. When evaluating the permeable surfacings in accordance with the results obtained, a negative point of view is being arisen in relation with such type of structures. IX Inspite of this, all of the surfacings researchers- are in the opinion that such type of surface is subject to the improvements of the permeable suracing. In this respect, the recommendable range of new works and studies can be submitted to the attentions of the related researchers as implemented recommendations: - To provide high -resi s ted and high -rate pored concrete. - Improvement of practical methods applicable to the pore cleaning of the surfacings.