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Strength Characteristics of Clay Mixtures with Waste Materials in Freeze-Thaw Cycles Mahya Roustaei; Mahmoud Ghazavi Waste tires, rubbers, plastic and steel materials, normally produced in every society, enter the environment and cause serious problems. These problems may, to some extent, be reduced by finding applications for them in engineering, for example, they can be used for geotechnical applications as backfill material and solving problems with low shear strength soils. Such materials may be subjected to freeze-thaw cycles, resulting in strength reduction. Freeze–thaw cycling is a weathering process which is normal in cold climates. In these cycles, thermodynamic conditions at temperatures below C cause translocation of water and ice which can change the engineering properties of soils. The present study investigates the effect of reinforcing soil with tire chips and steel fibers to reduce the effects of freeze-thaw cycles. To this aim, reinforced kaolinite clay was compacted in the laboratory and exposed to a maximum of 6 closed-system freeze-thaw cycles. The results of the study reveal that adding tires to clay prevents strength reduction due to freeze-thaw cycles. The soil samples which were mixed with 2% of steel fibers and 10% of tire chips were not affected by the freeze and thaw cycles as the pure samples were. These materials can reduce the effects of freeze and thaw cycles especially in cold regions. منبع دانلود JSEG171329597000.pdf

Investigating the Distribution and Orientation of Steel Fiber Reinforced Concrete Original Article, B34 Zandi Y. Journal. Civil Eng. Urban. 2(5): 191-195. 2012. ABSTRACT:The distribution functions of fiber location variables were investigated that can be used to produce an analytic model to predict the mechanical properties of SFRC. Considering the effect of surrounding boundaries and distribution function, theoretical expressions were derived for the number of fibers per unit cross sectional area in SFRC. A comparison between empirical results and the theory were done to confirm the analytical results. Fibers are usually used in concrete to control cracking due to both plastic shrinkage and drying shrinkage. The amount of fibers added to a concrete mix is expressed as a percentage of the total volume of the composite (concrete and fibers), termed volume fraction (Vf). Vf typically ranges from 0.1 to 3%. Fibers with a non-circular cross section use an equivalent diameter for the calculation of aspect ratio. Keywords:steel fiber reinforced concrete; steel fibers; vibration, distribution function. منبع: [Hidden Content] دانلود: [Hidden Content],%20B%2034%20191-195.pdf JCEU, B 34 191-195.pdf