Coal gangue ceramsite high-strength concrete with lightweight characteristics: Towards deep shaft linings in the drilling method

With increasing shaft depth in the drilling method, the self-weight of the deep shaft linings also increases, making it difficult for them to float in the mud based solely on their own buoyancy. Consequently, numerous auxiliary steel beams are required to temporarily support the lining sections, making the process slow and laborious. To address this issue, this study develops coal gangue ceramsite high-strength concrete (CGCHSC) with lightweight characteristics for deep shaft linings using the drilling method and evaluates its feasibility. Experiments with range and variance analyses investigate the effects of the water-binder ratio, CGC content, steel fiber volume fraction, and water-reducing agent dosage on the compressive strength at 7 and 28 days, the ratio of 7-day to 28-day compressive strength, the splitting tensile strength at 28 days, and the ratio of splitting tensile to compressive strength. Then, for the first time, an Analytic Hierarchy Process–Improved Criteria Importance Through Intercriteria Correlation–Efficacy Coefficient Method (AHP–Improved CRITIC–ECM) is applied to design CGCHSCs with lightweight ( ρ OD : 1942–2054 kg/m 3 ), high strength ( f cu,28d : 44.5–102.8 MPa; f st,28d : 3.14–7.54 MPa), and pumpability (slump: 140–220 mm). Finally, we explore the feasibility and technical advantages of using CGCHSC for deep shaft linings. Results show that CGCHSCs reduce shaft linings weight by 17–24 %, lowers stresses compared with traditional linings, and decrease the number of auxiliary steel beam sections from 14 to 2. This study provides a reference for the further application of CGCHSC in shaft lining by drilling method.