Field comparative studies of the efficiency of modern technologies and materials for irrigation canals waterproofing
Abstract
Purpose: to conduct a field comparison of four technologies and materials for waterproofing irrigation canals and to select the optimal solution based on a combination of hydraulic, operational, and economic indicators under high water mineralization and intense climatic impacts typical for the Southern Federal District. Materials and methods. The objects of the study were six irrigation systems with a total canal length of 45.5 km. Cement-sand mortar (T1), polymer-cement composite (T2), bitumen-polymer emulsion (T3), and modified fiber-reinforced concrete with silicon dioxide and an aqueous alkaline solution of sodium silicates (T4) were successively used on test sites with identical hydraulic parameters. The efficiency was assessed on the basis of water impermeability measured by the AGAMA-2RM device, seepage losses calculated using a refined formula taking into account the hydraulic gradient, adhesion recorded by the normal pull-off method, frost and sulfate resistance, and life cycle cost over a 50-year design period. Statistical processing was performed using the Student's t-test and one-way ANOVA test. Results. Modified fiber-reinforced concrete ensured a reduction in seepage losses by 85–90 % (p < 0.01), water resistance grades W12–W14, adhesion of 1.98–2.35 MPa, and an estimated period between repairs of 40–50 years. At a real discount rate of 9.4 % per annum, the life cycle cost of T4 option was 41.2 million rubles/km versus 59.3 million rubles/km with traditional cement-sand repairs, which corresponds to a 1.44-fold reduction, a net discounted effect of RUB 18.1 million/km for the calculation period, and an average annual effect 1.72 million rubles/km. Water savings amounted to 75,000 cubic meters per year per 1 km of canal. Conclusions. Modified fiber concrete is recommended for waterproofing irrigation canals with water mineralization above 2.0 g/l and sulfate concentrations above 1000 mg/l. This advantage is consistent across the entire range of discount rates studied.