Ceramics-Silikáty 67, (4) 403 - 410 (2023)

This study investigates the influence of different dosages of polycarboxylate superplasticisers on the mechanical properties of a High-Strength Engineered Cementitious Composite (HSECC), including the compressive strength, flexural strength, tensile properties, and bending toughness. The distribution of polyethylene (PE) fibres in the hardened body of the HSECC is also analysed using scanning electron microscopy (SEM). The results indicate that the mechanical properties of HSECC present a first decreasing and then increasing trend with the increasing superplasticiser dosage, while the tensile ductility exhibits the opposite trend. The inflection points of the tensile properties are observed within the superplasticiser dosage range of 0.35wt.%~0.4wt.%. The SEM analysis of the fibre distribution in the specimen cross-section reveals that the addition of a defoaming agent alters the workability of the fresh mortar, resulting in a decrease in the fibre dispersion coefficient from 73.0% to 65.1%, a reduction of 10.8%. Gradually increasing the superplasticiser dosage to 0.35wt% increases the fibre dispersion coefficient to 74.5%. These findings suggest that the optimal dosage of the superplasticiser for HSECC lies within the range of 0.35wt.%~0.4wt.%, which can enhance the mechanical properties of the HSECC while maintaining good fibre dispersion.