Advanced ultrasonic characterization of recycled steel fiber-reinforced mortars: Integrating nonlinear parameters for optimal fiber dosage determination. - Amjad U; Irshidat MR; Alnuaimi H; Maurya MR; Albeitjali N; Razack RK; Kailani HY; Sadasivuni KK; Kundu T (Science progress, 2026)