ASSESSING THE INFLUENCE OF CONCRETE STRENGTH ON ITS PERMEABILITY OF CONCRETE CHANNEL USED FOR IRRIGATION IN QAZVIN PROVINCE

The open channels, which provide the optimum sections, have been mostly used in irrigation systems in Iran, in recent years. Irrigated agriculture has been playing a vital role in the growth in crop production in IR of Iran. An open channel is a conduit in which water flows with a free surface. The free surface is subjected to atmospheric pressure .among the gravity systems used for transfer water with open surface flow and it is necessary that hydraulic structures, such as spill ways floodgate, etc., be the most popular irrigation systems for use in Iran. Therefore, in this paper, the strength and permeability of concrete lining of an ancient open channel are presented, while the strength of the concrete is determined by the ``Twis-off'' method. , The newly developed ``Silindrical Chamber'' method is used for measuring the permeability of the concrete lining. The results obtained show that a meaningful and positive correlation appears to exist between the two parameters studied. The "twist off" method is an in-situ method in which an aluminum probe sticks to the surface of the concrete under test, using epoxy adhesive; after setting and hardening of the epoxy, torquemeter is used to determine the concrete strength by measuring the maximum or failure torque. The newly developed method for permeability consists of a portable permeability measuring device that can be used under both laboratory and site conditions. In this method, an aluminum base ring sticks to the surface of concrete under test using epoxy adhesive; a cylindrical chamber is attached to the base ring after hardening the epoxy resin. The chamber is filled with water and its air bubbles are released by opening a valve designed for this purpose. The permeability of the concrete surface is measured by applying 5- bar pressure to the chamber water.