Application of tunnel excavation rock as aggregate: Effect of aggregate characteristics on manufactured sand mortar

This study investigates tunnel excavation crushed rock for concrete preparation, examining river sand (RS), tuff manufactured sand (TMS), and granite manufactured sand (GMS) in an air-dried state. Variables include aggregate type, gradation, flake particle content, and stone powder content (SP), analyzing their effects on mortar fluidity, mechanical properties, and drying shrinkage. Results show RS mortar exhibits optimal fluidity, while GMS mortar achieves the highest 28-d compressive strength (70.40 MPa). Appropriate gradations and SP improve compressive strength, but excessive SP disrupts particle packing. RS mortar demonstrates minimal drying shrinkage (868 με), while SP negatively impacts shrinkage performance in manufactured sand mortars. Hydration kinetics analysis reveals SP accelerates early hydration but reduces cumulative heat. Correlation analyses indicate SP most significantly influences mortar macroscopic behavior among aggregate parameters. Key hydration parameters including NG process reaction rate and chemical bound water critically affect mortar properties.