Effect of Substitution of Cement by Mineral Powders on the Physicomechanical Properties and Microstructure of Sand Concretes

The approach that contributes to the development of eco-materials in construction is the use of mineral powders, which can improve mechanical properties and reduce cement consumption. This article aims to study the effect of substitution by mass of cement with mineral powders on the physicomechanical properties and microstructure of sand concretes. The used mineral powders are A: the limestone, B: the natural pozzolan, C: the hydraulic lime, D: (1/3 limestone + 1/3 natural pozzolan + 1/3 hydraulic lime), and E: (1/2 natural pozzolan + 1/2 hydraulic lime). The studied percentages are 5%, 10% and 15%, in both separated and combined states. The studied properties are workability, compressive strength, the elasticity modulus in compression, shrinkage and microstructure analysis. The objective is to target the optimal percentage of the substitution of cement with mineral powders, which ensures the best compromise between the main properties of the studied sand concretes. The obtained results show that the optimal percentage is in favor of the substitution of cement by 10% D (1/3 limestone, 1/3 natural pozzolan and 1/3 hydraulic lime). Even the 15% of mineral powder D, presented similar performances compared to the sand concrete (without mineral powders). Finally, in the context of the development of eco-materials, it should be noted that the 10% D and 15% D (1/3 limestone, 1/3 natural pozzolan and 1/3 hydraulic lime) contribute to decrease the use of cement and consequently to reduce of CO2 emissions.