عنوان مقاله [English]
To evaluation of irrigation canals lining, uaually compressive strength is determined, whereas new studies proved that this paprameter can't guarantee lining durability during its lifetime. Durable concrete in cold climate can save its serving in lifetime. In this paper durability of hardened concrete in irrigation canals in Bahar plain in Hamedan province were evaluated and results were compared with prescribed standards. For this purpose, 5 concrete lined canals were selected to study and field and laboratory examinations were done. Name of selected canals is Gondejin, Bahadorbeig, Abroomand, Khooshab-olia and Komooshboolaghi. Field examinations were including: 25 samples coring from these canals. Laboratory examinations were including: determination of specific gravity, initial and final water absorptions, depth of water penetration in cores. Results showed that mean values of specific gravity, initial and final water absorptions, depth of water penetration in cores were 2.1 gr/cm3, 5.8%, 7.7% and 79 mm respectively. Based on prescribed standards mean values of these parameters must be 2.4 gr/cm3,3%, 5% and 30 mm respectively. With comparision results and prescribed standard values, it can be noted that measured mean values of specific gravity of cores is 15% less than standard. Initial and final water absorptions and depth of water penetration in cores are 3, 1.5 and 2.5 time, respectively, more than those in standards. These results express that concrete lining of studied irrigation canals is undurable for freezing-thaw condition. High permeability and high water absorption of cores is due to high porosity and low compaction. Field observations confirmed these conclusions. Because of unsuitable durability of cores, it can be concluded that concrete lining in studied canals are not secure lining in front of freeze- thaw cycles in their lifetimes..