Experimental study of architectural LECA and Scoria lightweight cast stone

The compressive strength of concrete is directly dependent on the coarse aggregate. However, the presence of coarse aggregate can lead to surface heterogeneity, which may be undesirable in architectural applications of concrete, especially in building facades. Lightweight facade elements contribute to reducing the vertical load of the building and the seismic forces in horizontal directions, resulting in improved structural performance and cost efficiency. Simultaneously achieving sufficient compressive strength, esthetic appearance, durability against weathering, and minimizing weight are four key factors that must be considered for facade materials. In this research, by eliminating coarse aggregate and utilizing lightweight aggregates (lightweight expanded clay aggregate [LECA], Scoria, and LECA–Scoria blend), along with experimenting with various mix designs, concrete admixtures are proposed that optimally meet these criteria. Within the framework of American Society for Testing and Materials standards, it was observed that the proposed concrete admixtures exceed the minimum required compressive strength of 35 MPa for architectural cast stones, have water absorption rates below the allowable maximum of 6%, and demonstrate acceptable carbonation resistance. Additionally, a significant reduction in density was achieved compared to conventional concrete. To ensure surface quality and homogeneity, which are critical in architectural esthetics, an innovative intelligent algorithm was proposed to evaluate the surface quality of the concrete samples. It was found that all samples were classified in the highest CSC4 category, according to American Concrete Institute 347.3R‐13. In conclusion, it can be inferred that the proposed concrete in this study can be considered a suitable option for building facades. The economic aspects of production and installation, though beyond the current scope, present a valuable direction for subsequent investigations.