e purpose of this research was to investigate the effects of recycled asphalt pavement (RAP) and cement content on the permeability and bearing capacity characteristics of aggregate base courses. Mixtures containing untreated RAP ranging between 0 and 100 percent and 1, 2, and 3% cement-treated RAP were subjected to laboratory tests (bitumen content, sieve analysis, modified proctor, soaked California bearing ratio (CBR), and constant-level permeability tests). e results showed that, as the RAP percentage in the mixture increased, CBR values decreased considerably. Moreover, there is a linear increase in the CBR values with cement treatment. Optimum moisture contents (OMC) and maximum dry densities (MDD) showed a decreasing trend. Increasing the cement percentages in 100% RAP blend increases the OMC and MDD values. e permeability of RAP showed a decrease as the percentage of RAP and cement increased in blends. e study showed that the CBR value of the 20% RAP blend is also obtained in the 100% RAP/3% cement-treated blend. us, it has been understood that cement is a suitable material in order to increase the use of RAP. In addition, the increase in the percentage of RAP and cement made the base course more impermeable.
The objective of this research was to assess the elastic deformations and permanent strains of reclaimed asphalt pavement (RAP) material as a base layer when it is treated or untreated with pozzolanic cement under cyclic loads. A large-scale cyclic plate loading testing (CPLT) device was developed for studying the mechanical characteristics of pavement base layer. The laboratory test results indicated that when the RAP percentage of the mixtures increased, elastic deformations and permanent strains increased, but the opposite was true when the cement percentage increased. It was concluded that 100% RAP material can be used in base layers with 3% pozzolanic cement. The obtained deformation values and strain rates can be used as reasonable default design input values by pavement designers when using RAP as a substitute for natural aggregate base layers.
Türkiye'de beton yolların kullanımı her geçen gün artmaktadır. Özellikle Doğu Karadeniz Bölgesi'nde 10.000 km'nin üzerinde beton yol bulunmaktadır. Bu çalışmada, Trabzon ve Rize İllerinde yapılan beton yol uygulamaları incelenerek yaygın olarak kullanılan kaplama kalınlığı ve beton basınç dayanımı belirlenmiştir. Karadeniz Teknik Üniversitesi Hızlandırılmış Yol Tesisinde örnek kaplama modeli hazırlanmış ve gerçek trafik yüklemeleri altında beton kaplamaların düşey deplasman değişimleri incelenmiştir. Farklı derz türleri (hasır donatılı yarım derz, donatısız yarım derz, dolgulu tam derz ve dolgusuz tam derz) kullanılarak fayda ve maliyet analizi yapılmıştır. Elde edilen verilere göre, derzlerin yarım derz olması ve kaplamada donatı kullanılması, donatısız yarım derzlere göre 1.3 kat, dolgulu tam derze göre yaklaşık 4 kat, dolgusuz tam derzlere göre ise yaklaşık 9 kat daha az düşey deplasman oluşmasını sağlamaktadır. Ayrıca yapılan maliyet analizlerine göre kaplamalarda hasır donatının bulunması, beton kaplama maliyetine km'de 38.002,76 TL (%11,6) fiyat farkı oluşturmaktadır. Bu bilgiler ışığında, beton kaplamalarda yarım derz yapılmasının ve hasır donatının kullanılmasının kaplama derz bölgelerindeki faydasına oranla maliyetinin oldukça düşük olduğu sonucuna ulaşılmıştır. Ayrıca mevcut tam derzli beton yollarda %7'lik ilave bir maliyet ile derzlerin içinin bitüm esaslı dolgu malzemesi ve kauçuk levhalarla kaplanmasının, düşey deplasman değerlerini en az yarı yarıya azaltılabileceği ve bu sayede kaplama ömrünün uzatılabileceği tespit edilmiştir.
Joint gaps between slabs in underlying Portland cement concrete (PCC) pavements are critical factors in the life span of asphalt concrete (AC) overlays. Therefore, being informed about the vertical deflections that may occur around the joints is important. In this study the joints were reinforced with three different materials: ethylene propylene diene monomer (i.e., rubber joint filler [RJF] reinforcement), bitumen-based sealant (i.e., rubber plate [RP] reinforcement), and steel plate (SP) (i.e., SP reinforcement), to limit the vertical movement of the underlying PCC. Tests were conducted at the accelerated pavement testing facility for two different AC overlay thicknesses, 50 mm and 100 mm, during 100,000 passages to investigate the influence of AC overlay thickness variations on slab vertical deflections and to also evaluate types of joint reinforcement on slab vertical deflections. For 50-mm thick AC overlay, the most effective joint reinforcements to prevent deformations caused by loading were RP, RJF, and SP; for a 100-mm thickness, this was determined to be RJF, SP, and RP, respectively.
Tunnels are road transport structures that reduce traffic and expropriation problems, noise, and possible damage to animals and plants, and provide safer, more comfortable, and faster transportation for vehicles compared to highways. However, some environmental problems occur during tunnel construction. These problems such as vibration, noise, rock throwing, etc. caused by the blasting process used during tunnel excavation on buildings and people should be well investigated. In this study, two buildings located close to the exit and entrance of two tunnels (T2 and T3 tunnels) on the Gümüşhane belt road were chosen to investigate. Firstly, the existing damages in the first building, which is 7 m away from the T2 tunnel exit, and the second building, which is 60 m away from the T3 tunnel entrance, were analyzed by considering criteria such as the geological and ground condition of the land and the building materials used during the construction of those building. In addition, the negative effects on the buildings were evaluated by calculating the vibrations after the blasting process in the tunnel with the help of various empirical formulas. Investigation on site showed that building 1 was built of masonry and building 2 was built of reinforced concrete, and that deep cracks had formed in the bearing systems of both buildings, spills occurred in the walls, and fractures in the windows. Also, calculations with empirical formulas showed that the vibration rates caused by blasting process in the 1st and 2nd buildings were as 385.68 mm/sec and 6.91 mm/sec, respectively, and these vibration values were above the standard values. The data obtained through examination on-site and empirical approaches show that it would be dangerous for people to be resident in both buildings.
Transverse contraction joints are by far the most common type of joint in jointed plain concrete pavements. Early loading of contraction joints can create a weakened vertical plane and later grow as a full-depth crack. In this study, load transfer efficiency (LTE) of steel mesh reinforced transverse contraction joints were studied at accelerated pavement tests (APT). 3D finite element (FE) model of jointed plain concrete pavement (JPCP) was developed to study deflections and crack propagation in just under the joint of the concrete pavement. The APT tests were focused on the LTE values before and after the crack initiation under the contraction joint region. Experiments were performed on three slabs in which two of these slabs were prepared without reinforcement and one of them was reinforced with steel mesh. Data generated by APT was used for verification of crack propagation modeling in the finite element analysis. Steel mesh reinforced slab gave the lowest vertical deflections (51μm) and highest LTE (91.56%). The LTE value in the reinforced slab after 25,000 passes was 13.63% higher than the average of unreinforced slabs. The findings suggest that the load transfer efficiency was found to be a complex parameter and should be interpreted together with average displacement values when contraction joints are evaluated at early traffic loadings.
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