This article aims to evaluate the mass transport properties in concretes with different contents of polypropylene microfiber (0% and 1%, by concrete volume) and crystalline admixture (0%, 1%, and 3%, by cement mass). Water absorption by immersion, water absorption by capillarity, and air permeability tests were performed to evaluate the properties of mass transport. Images of the microstructure of the concretes were used to support the hypotheses discussed. The tests were performed immediately after curing (28 days) and after curing plus 35 and 70 days of wetting and drying cycles. The combined use of polypropylene microfibers and crystalline admixtures may increase the properties of mass transport at an early age. Nevertheless, the nucleation of hydrated phases around polypropylene microfibers contributed to the densification of the concrete pores over time. The crystalline admixture can close larger pores and reduce connectivity between them in the first ages (first 35 days). However, the effect of crystalline admixtures in filling capillary voids requires more time to occur (around 70 days). The void index was reduced between 0 and 70 days by 47%, 42%, and 44% for reference, F + 1CA, and F + 3CA concrete mixtures, respectively.

本文旨在评估具有不同含量聚丙烯微纤维（0% 和 1%，按混凝土体积）和结晶外加剂（0%、1% 和 3%，按水泥质量计）的混凝土的传质性能。进行浸渍吸水、毛细管吸水和透气性测试以评估传质性能。混凝土微观结构的图像用于支持所讨论的假设。测试在固化后（28 天）和固化后加上 35 天和 70 天的润湿和干燥循环后立即进行。聚丙烯微纤维和结晶混合物的结合使用可能会在早期提高质量传输的特性。尽管如此，随着时间的推移，聚丙烯微纤维周围水合相的成核有助于混凝土孔隙的致密化。在最初的年龄（最初 35 天），结晶混合物可以关闭较大的孔隙并减少它们之间的连通性。然而，结晶混合物填充毛细管空隙的效果需要更多的时间（大约 70 天）。对于参考、F + 1CA 和 F + 3CA 混凝土混合物，空隙指数在 0 到 70 天之间分别降低了 47%、42% 和 44%。