Mix Design and Performance Analysis of Concrete with Limestone Powder Admixture

The use of waste limestone powder from mining to replace natural sand in concrete improves its mechanical performance and durability, reduces production costs, and benefits the ecological environment. In the initial mix design, limestone powder was substituted for natural sand as fine aggregate at specific ratios under constant total mass, investigating the influence of water-to-binder ratio and limestone powder replacement rate on concrete strength to establish preliminary value ranges for the optimal parameters. The secondary mix design employed Design Expert software 13 to develop a response surface model, analyzing the impact of water-to-binder ratio and limestone powder replacement rate on key mechanical properties like compressive and flexural strength, as well as the durability of the concrete containing limestone powder. Furthermore, Digital Image Correlation (DIC) was utilized to monitor the stress-strain state on the concrete surface, with the resulting strain cloud maps used to characterize crack initiation locations and propagation patterns. Overall, the results indicate that the observed performance evolution was governed by the coupled influence of limestone powder replacement rate and total powder content. Under the present experimental conditions, limestone powder demonstrated potential as a sustainable fine aggregate substitute; however, its intrinsic contribution could not be completely isolated because of the simultaneous variation in powder content. The study further clarifies the coupled influence of limestone powder replacement rate and total powder content, while integrating response surface optimization and DIC analysis method to provide a practical framework for limestone powder concrete design and engineering application.