Crack Resistance for Rockfill Dam Concrete Face Slabs Based on through Experimental Investigation and Entropy Weight Method

Abstract

The harsh climatic conditions in alpine regions often pose challenges to the construction of concrete face rockfill dams. The purpose of this study is to investigate the enhancement of crack resistance in hydraulic concrete for face slabs by systematically comparing internal admixtures including nano-calcium carbonate (NCC), silica fume (SF), silica fume-fly ash composite (SF-FA), magnesium oxide (MgO), and anti-seepage crack-resistant material (ACM). A two-phase experimental approach was adopted: Phase I optimized a reference mix (water-to-binder ratio of 0.35-0.36, fly ash content of 20-30%) for the target project, while Phase II systematically evaluated the workability, mechanical properties, deformation, and durability of the modified concrete. Experimental findings show that SF significantly enhanced mechanical strength, increasing the 28-day compressive strength to 50.1 MPa, while NCC and ACM effectively reduced the 90-day drying shrinkage strain to approximately 300×10−6 , compared to 380×10−6 for the reference mix. To address inconsistencies in traditional single-index evaluations, an intelligent assessment framework based on the Entropy Weight Method (EWM) was developed, integrating multi-dimensional performance data into a Comprehensive Crack Resistance Index (CCRI). The EWM-based analysis ranked SF, NCC, SF-FA, and MgO as the top four performers based on CCRI. However, considering fresh concrete workability constraints, NCC-concrete, with a slump of 70 mm and the highest overall stability, was identified as the optimal material solution. This datadriven approach provides a validated strategy for enhancing the crack resistance and long-term durability of CFRD face slabs in dry, windy alpine environments.