Bаsheer N. The technology of modified concrete pipes for drainage and irrigation networks in Iraq

This thesis presents the results of research to develop technologies non-reinforced concrete pipes of the modified piping of irrigation and drainage. As in Ukraine, and Iraq is a need for cost-pipes for sewage systems and irrigation. Today's decision of transporting liquids are closed pipes made of concrete and reinforced concrete pipes. Given the scarcity of metal in Iraq, the preference for economic indicators should be given concrete (without metal reinforcement) pipes. The most economical are the gravity-pressure piping systems with working pressure 1,5 - 2,5 atm, but according to the standards for conventional concrete pipe working pressure is limited to the pressure of 0.9 atm, with the strength requirements for concrete are presented in the form of brand or class of compressive strength. By transforming the known dependence for determining normal ring voltage from the external load and internal pressure, obtained new transformed according to the calculation of stresses in pipes under combined internal pressure and external (reduced) loads. Calculations showed that for the pipe material strength of the key indicator in determining the carrying capacity is the strength of concrete in tension. Investigations of its value depending on the amount of modifying additives introduced into the concrete. Successfully applied inorganic additives: silica fume, fly ash, organic: PVA, P-3; nonmetallic reinforcing fibers developed ways of improving the strength of concrete in tension by its modifications, improved methods of sealing. The method of radial compression, which is forming tubes in two stages, which requires the use of two cores. Iteration method used to determine the optimal amounts of input modifiers. The complex of these methods makes it possible to obtain material for pipes which can be used instead of concrete for low-pressure irrigation conduits. The strength of modified concrete increased by 2 times compared with conventional concrete. The necessary geometric dimensions of pipes, the relevant standard requirements for depth of laying. Based on these standards, the requirements for strength, namely, the standard value reduced to an external load, which is given in all regulatory documents. A calculation found that the working pressure for pipe made of modified concrete can be increased by 3 times. The technology of molding elements of a complex configuration for the pipelines (tees and pipes).