Application Research of Maturity Indicators in Interlayer Quality Control of Roller-Compacted Concrete Dams: A Case Study of the Kafue Gorge Lower Hydropower Station in Zambia

The quality of interlayer bonding in roller-compacted concrete dam construction is significantly influenced by environmental factors, and traditional methods for determining initial and final setting are ill-suited for complex field conditions. Based on the Lower Kafue Hydropower Project in Zambia, a quality control method integrating maturity indicators and interlayer exposure time is proposed. Through designing and conducting field tests, roller-compacted concrete specimens were evaluated under varying exposure times (4–62 h) and interlayer treatment methods (cement slurry treatment, mortar treatment, no treatment, roughening, etc.). Based on a maturity calculation model, interlayer joints were classified into three categories—“hot joints,” “warm joints,” and “cold joints”—with corresponding evaluation criteria and treatment measures established. Experimental results indicate that shorter interlayer exposure time and lower maturity yield higher interlayer bond strength. Cement slurry treatment outperforms mortar treatment, while roughening further enhances bonding quality. A dynamic adjustment model based on monthly average temperatures effectively guides construction decisions under varying climatic conditions. Engineering applications demonstrate that this method enhances interlayer bonding quality and construction controllability, thereby ensuring the quality of interlayer pouring in roller-compacted concrete dams and improving the overall quality of such dams to meet design requirements.