INTEGRATED ASSESSMENT OF LOCAL AGGREGATES AND CHATKAL RIVER WATER SUITABILITY FOR CONCRETE STRUCTURES OF THE LOWER CHATKAL HPP

This paper develops an integrated methodology for assessing the suitability of local aggregates and Chatkal River water for concrete and hydraulic structures of the Lower Chatkal Hydropower Plant in Bostanlyk District, Tashkent Region. Public project information indicates an installed capacity of 90 MW and the use of roller-compacted concrete (RCC) for the dam. Excavated material from the common foundation pit was processed in an on-site crushing and screening plant rated at 500 t/h to produce sand and crushed-stone fractions for concrete. A testing matrix was established with reference to ASTM C33/C33M, EN 12620, GOST 8267 and GOST 8736 for aggregates and ASTM C1602/C1602M, EN 1008 and GOST 23732 for mixing water. Because complete laboratory protocols from the Lower Chatkal construction site are not publicly available, no site-specific chemical values are fabricated. Instead, peer-reviewed hydrochemical data published in 2024 for the Chirchik–Akhangaran basin are used strictly as regional background. In that study, upstream Chirchik-system waters showed pH values of 7.4–8.0 and electrical conductivity of 163–266 µS/cm. Comparison with mixing-water requirements suggests that the regional background is compatible with a potentially favorable hydrochemical environment; however, final acceptance requires direct measurements of chlorides, sulfates, alkalis and total dissolved solids together with concrete/mortar performance tests. The study therefore classifies local aggregates and Chatkal River water as potentially suitable subject to laboratory confirmation and demonstrates why separate acceptance criteria are required for RCC mass concrete, reinforced concrete and high-strength abrasion-resistant M800 concrete used in hydraulic flushing structures.