Abstract As an emerging alternative cementitious binder, alkali activated slag (AAS) is gaining great attention, but considerable shrinkage caused by alkali activation and drying limit its potential applications. Herein, we demonstrate that the addition of an environmentally benign biofilm, cultured from B. subtilis, mitigates both the autogenous and drying shrinkage of AAS. The influences of the biofilm on the hydration kinetics, water absorption and strengths are investigated. Results show the addition of the biofilm increases the hydrophobicity of the pore wall, which in turn decreases the capillary tension. The hydrophobic modification by the biofilm significantly reduces the water loss from the AAS to its direct environment (up to 86% at 35 d exposure). Consequently, both autogenous and drying shrinkage of AAS are dramatically reduced. Moreover, a new mechanism is proposed to explain the mitigation of AAS shrinkage, which takes into account the increase in internal RH and reduction in capillary pressure.

中文翻译：

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用生物膜减轻碱活化渣的收缩

摘要 作为一种新兴的水泥基粘合剂，碱活化矿渣（AAS）受到了广泛的关注，但碱活化和干燥引起的相当大的收缩限制了其潜在的应用。在此，我们证明添加从枯草芽孢杆菌培养的环境良性生物膜可以减轻 AAS 的自体收缩和干燥收缩。研究了生物膜对水合动力学、吸水率和强度的影响。结果表明，生物膜的加入增加了孔壁的疏水性，进而降低了毛细管张力。生物膜的疏水改性显着减少了从 AAS 到其直接环境的水分流失（暴露 35 天时高达 86%）。因此，AAS 的自收缩和干燥收缩都显着降低。