Geçirimli esnek üst yapılar

Abstract

Geçirindi esnek yol üstyapısının incelendiği bu çalışma dört ana bölümden oluşmaktadır. Giriş kısmı olan birinci bölümde geçirindi kaplamaların kısaca niçin gereksinim duyulduğu, mekanik özellikleri ve dünyadaki kullanım alanları açıklanmıştır. îkinci bölüm de, geçirindi üstyapılar ayrıntılı olarak tanıtılmıştır. Geçirindi üstyapıların seçim kriterleri üzerinde durularak, kullanım alanları ve özellikleri verilmiştir. Geçirindi Üstyapıların özellikleri tanıtılırken; yüzey özellikleri, yapısal ve fonksiyonel özellikleri ile bakım ve onarımları açıklanmıştır. Deneysel çalışmaları içeren üçüncü bölümde ise deney çalışmaları için aşağıdaki beş seçenek kullanılmıştır. Birinci seçenek olarak, agrega karışımına göre ağırlıkça %S taş tozu, %30 (0-1 0#>, %78 <3/4#-3/8#> gradasyona sahip malzeme ve %3 -3.5-4-4.B oranında bağlayıcı içeren 67 penatrasyonlu asfalt çimentosu kullanılarak yapılan deneylerde en uygun boşluk %21 oranına karşılık gelen en iyi Marshall stabilitesl değeri 400kg bulunmuştur. Bu değerler %4 bağlayıcı oranında elde edilmiştir ve daha sonraki deneylerde %4 bağlayıcı oranıyla çalışılmıştır, îkinci seçenekte, agregaya göre ağırlıkça %2 Portland çimentosu, ?, %78 1 3/4 *-3./8# > agrega karışımı kullanılmıştır ve ?S22 boşluk oranına karşılık 43B kg ' lık Marshall stabilitesi değeri bulunmuştur. Üçüncü seçenekte agregaya göre ağırlıkça %6 Portland çimentosu, %a0 (0-1 0#>, %74 (3/4#-3/8#), agrega karışımı kullanılmak suretiyle %19 boşluk oranı ve 465 kg'lık Marshall stabilitesi değeri bulunmuştur. Dördüncü seçenekte agregaya göre ağırlıkça %1Ö Portland çimentosu, %30 (0-10 >, %70 (3/4 # -3/8 ) agrega karışımından %18 boşluk ve B71 kg'lik Marshall stabilitesi değeri elde edilmiştir. Beşinci seçenekte agregaya göre ağırlıkça ?-62 Portland çimentosu, Î^O (0-1 0#>, %78 (l/a# ~3/8#> agrega karışımı kullanılmasıyla VAİ boşluk oranına karşılık 476 kg'lık stabilite değeri tesbit edilmiştir. Deney sonuçlarının değerlendirilmesi sonunda karışımda iriagreganm fazla olmasının boşluk oranını ve geçirimliliği arttırdığı fakat stabiliteyi düşürdüğü buna karşılık ince agreganın artması ve iri agreganın karışımdaki oranının düşmesinin ise stabiliteyi arttırdığı fakat boşluk oranını düşürdüğü gözlenmiştir. Ayrıca bu bölümde hasırlanan bu karışımların özellikleri dikkate alınarak hidrolik projelendirme yapılmıştır. Dördüncü bölümde deneysel çalışmaların genel değerlendirilmesi sunulmuştur.

This study consist of 4 main parts In the first chapter requi rementsof porous flexible pavements its mechanical properties and applications around the word was revealed. Porous pavements has a high void ratio, almostBO% of surface water immediately get inside it. İt store the surface water before go to the drainage system. In the second chapter this properties, benefits and drawbacks of porous pavements areexplained. Selection criteria of porous pawements Application of this type of pavement has been increasing in European countries since 1980's years. As a result of this these countries have quite a lot experiencein this subject. According to this experience advantages and disadvantages of porous pavement are summarised as follows: Advantages : - Road surface can be maintain dry when it rain. - Because of its high voild ratio, it provides much more rough surface than ordinary pavement. - It has high sound absorption. It increases skid resistance. It reduces water amount which is splashed by vehicles and also canses to reflection. Because of higher skid resistance. It prevents the vehicles to be thrown out by centrifugal force. Reduces sounds created by traffic movements. It has higher resistance to platic deformations. VI Disadvantages : - Poor physical endurance. As the void ratio increases, the resistance to external effects decreases. To solve this problem high adhesive cements must be used. - Poor functional endurance Voids in porous pavements are filled after passing a certain time and this prevents its spesific duty. AdditionalH it is sensitive to enviromental and athmasperic pollution. - It must be applied an inpermeable surface. - Its maintenance is quite difficult. This sort of pavement is usually applied on motorways, urban highways, tunnels and the regions where the surface drainage is very difficult. Porous pavements must be maintained at least %10 of void ratio. This type of pavements require 2B% less asphalt then convent i nal pavements. Aggregate gradation by weight is as follows: 12-18 mm crushed stone &78 0-2 mm sand ?<£0 Filler ?-S2 These aggregates must have more endurance than ordinary pavement aggregates, designed for the same traffic volume. Aggregates should be crushed and angular. Most of them should be than 2 mm. There are two different concepts about this application in the world. - In U.S.A. it is laid in 2 cmm thickness with 0.10 mm grain sise. - In the European countries (especially in U.K> it is laid in 4 cm thickness with 0-14 mm or 0-20 mm grain vxx sise. There is no fixed gradation standard in these countries but in U.K. less amount of sand is used. Hydrolic properties of porous pavement as follows: It should immediateley provide the. rain water gets into the pavement. - During shower condition it should collect most of the water amount inside, the pavement and work as a reservoir. - It requires efficent dranage system under, pavement. Water level in a drained porous base layer can be calculated bH this equation. a h TT " H X t k n Height of water level over impermeabile surface. Distance between reference point and drain. Time Permeabilittj of material. Effective porosity of material. P : Intensity of rain. Thickness of porous pavement must be greater than H. Apart from this, to prevent pavement from disintegration thickness of pavement must be at kast 4 cm. Maintenanceof this type pavement i s very important Especially driving conditions become dangereous for driver. In such a casethe road must be treated for better conditions. In the third chapter. The experimental studies are explained. To find out best gradation five different choices detected. At the end of experimental study gradiation of the most suitable amount of asphaltic concrete permeability and higest stability are found. In the first choice gradation is as follows. (All valves are percent by weight) %2 Limestone dust, ?<20 CO-10) sieve crushed Limestone, %18 (3/4~3/8> sieve crusteh Limestone. With this gradation and %3-3. B-4. 0-4- B ashphaltic concrete by weight. 4 different mixed is prepored. Asphaltic concrete has 67 penetration value of 67. vxxi All mixes are tested for Marshall stabilitH value and void ratio in compacted specimens and the resultinadata is determined. The highest stabilitH and void rati oof the mixture has %4-0 asphaltic concrete by weight. After that all mixture is pregored according to this percent. In the second choice portland cement is used instead of Limenstone dust, Marshall stability value is found 435 In the 3 th coise portland cement percentage was increased to 6 percent. Aggregate gradiation percentages by weight are as follows f^O (0-10) and %18 (3/4-3/8). The highest values are 19 percent void ratio and 465 kg Marshall stability. In the 4 th choice portland cement percentage is more than 3 th choice and increased to 10 percent. Gradation is as the same as latter choice. The best values are 18 percent void ratio and 571 kg Marshal stabilit value. In the last choice portland cement percentage is 2 percent. The most suitable values are found 17 percent void ratio and 476 kg Marshal stability value. The results of those choices are If coarse aggregate ratio increases in mixes void ratio and permeability increase and stability reduces. But if fine aggregate ratio increases. Result is reverse. The best result is in the second choice. From the evaluation and analysis of test results obtained in the course of this investigation the following conclusions are drawn: - Target is to keep road surface dry during rain. - Because of drainage void ratio should be between 20-24 percent. - This can be maintained to choose a non-continous aggregate gradation. - To keep on mechanical properties of pavement at a certain level, all the aggregate must be crushed limestone. - Wheel loads reduce void ratio. For that reason during construction this should be taken into consideration. -To get the best result; optimum asphalt cement percentage should be selected form the highest stability. xx - The minimum pavement thickness must be equal to the maximum water height. - The environmental effects and weather conditions diturb the porous pavement easily because of its high void ratio. So the service life is reduced. - In winter, to prevent the icing on the road the amount of salt which spread on road must be twice in amount because of porosity. As a conclusion, despite of negative results such as low Marshall stability value and etc, this is.- a new sort of pavement and attemps can be made to overcome those negative results.