This study investigated the performance of nano silica-modified cementitious composites incorporating basalt fiber pellets (BFP), an emerging type of macro-fibers, under aggravated (alkaline and salt-frost) exposures relative to a reference exposure (moist curing). The composites comprised plain (cement) and blended (50% fly ash or slag replacement of cement) binder systems without/with nano silica and reinforced with two BFP dosages (2.5% and 4.5% by volume). The change of composites' physico-mechanical properties for both un-cracked and pre-cracked specimens were assessed under the three exposures. Furthermore, microstructural, thermal and mineralogical analyses were conducted to interpret the bulk trends. The results revealed that the alkaline exposure provided favorable conditions for the binders’ reactivity and hence microstructural development of the matrix; however, this was accompanied by reduction of ductility for un-cracked and pre-cracked specimens due to degradation of BFP. The matrix of the composites deteriorated physically and/or chemically under the salt-frost exposure, albeit to different extents according to the type of binder, especially for the pre-cracked specimens, the BFP remained intact though. The synoptic findings from this study highlighted the superior durability of the nano silica-modified cement-based (N-GU) and slag-based (N-G) composites reinforced with 2.5% or 4.5% BFP in harsh exposures.

本研究调查了掺入玄武岩纤维颗粒 (BFP)（一种新兴类型的粗纤维）的纳米二氧化硅改性水泥复合材料在相对于参考暴露（湿固化）加重（碱性和盐霜）暴露下的性能。复合材料包括普通（水泥）和混合（50% 粉煤灰或矿渣替代水泥）粘合剂系统，不含/含纳米二氧化硅并用两种 BFP 剂量（按体积计 2.5% 和 4.5%）增强。在三种暴露下评估了未开裂和预开裂试样的复合材料物理力学性能的变化。此外，还进行了微观结构、热学和矿物学分析以解释整体趋势。结果表明，碱性暴露为粘合剂的反应性和基质的微观结构发展提供了有利条件；然而，由于 BFP 的降解，这伴随着未开裂和预开裂试样的延展性降低。复合材料的基体在盐霜暴露下会发生物理和/或化学劣化，尽管根据粘合剂的类型不同程度不同，特别是对于预开裂的样品，BFP 仍然完好无损。