This research studied the effects of different types fibers (Basalt, Carbon and Basalt-Carbon hybrid mix) and curing ages (7, 14, 28 and 56 days) on some physical properties of - Slurry infiltrated fibrous concrete (SIFCON). Density, ultrasonic pulse velocity UPV, Poisson’s ratio and water absorption were measured for the experimental study with 30% cement replacement by Class F fly ash to increase sustainability. It was found that properties were significantly affected by the type and dosage of fiber admixture. The UPV was enhanced by basalt fibers and the absorption reduced up to an optimal range of 3–5% after which agglomeration led to a marginal decrease in performance. Carbon fibers demonstrated the greatest UPV value (4622 m3/s for 5% at 56 days) and lowest absorption value (2.4%), signifying its superior matrix densification ability. The combined system exhibited a synergistic state and achieved the highest UPV (4670 m/s) and balanced density (≈2024 kg/m3), with moderately low absorption (36%). Poisson’s ratio behaviors indicated that the fiber addition and aging led to higher lateral strain resistance and stiffness in carbon and hybrid structures. The results provide an overall confirmation that the addition of basalt and carbon fibers to SIFCON contributes to toughness, densification, and ultrasonic properties and help in implementing a sustainable material design with partial cement replacement by fly ash.
Mahmoud et al. (Wed,) studied this question.