碱激发矿渣/粉煤灰胶凝材料的收缩调控及其在多孔混凝土中的应用研究

Shrinkage and alkali aggregate reaction is the main factors of the alkali-activated blast furnace slag/fly ash based concretes, which affect their application. Previous studies indicated that the micro-expansive alkali-activated concrete was caused by the alkali-silicate reaction, but a little probability of expanded destruction was induced by alkali-silicate reaction in the alkali-activated concrete. Ground alkali active aggregates were added into the alkali-activated blast furnace slag/fly ash materials. The expansibility of alkali active aggregates can counteract the shrinkage of the alkali-activated blast furnace slag/fly ash materials, and improve the flexural strength of these materials. Relationships between the Si/Al ratios of raw materials, the Ca/Si ratios of raw materials and the composite of gels, the structure evolution of gels, the shrinkage properties of reaction products will be investigated. The microstructure modulation and enhancement mechanism of the alkali-activated blast furnace slag/fly ash materials will be established. The results of this project will provide the scientific support for reducing the shrinkage of alkali-activated blast furnace slag/fly ash materials, improving the toughness of these materials and designing the porous concrete drainage with good durability.

碱激发矿渣/粉煤灰混凝土的收缩和碱集料反应是影响其应用的主要因素。文献报道碱激发混凝土中的碱硅酸盐反应会产生微膨胀，但是膨胀破坏的几率很小。在碱激发矿渣/粉煤灰胶凝材料中加入磨细的碱活性集料，通过碱活性集料的微膨胀性抵消碱激发胶凝材料的收缩，提高碱激发胶凝材料的抗折强度，重点研究原材料中的硅铝比、钙硅比与凝胶相的组成、结构演变以及反应产物收缩性能的关系，构建碱活性集料在碱激发矿渣/粉煤灰胶凝材料的微结构调控和增强机理。本项目的研究成果将为减少碱激发矿渣/粉煤灰胶凝材料的收缩，增加该材料的韧性，设计出耐久性好的多孔混凝土排水基层提供理论基础。

为了降低碱激发矿渣/粉煤灰混凝土的开裂风险以及控制碱激发混凝土的水化反应热，本项目从原材料的组成、碱激发材料凝胶相的结构与性能系统研究了碱激发矿渣/粉煤灰胶凝材料收缩性能的调控机理。在碱激发矿渣/粉煤灰胶凝材料中加入磨细的碱活性集料，通过碱活性集料的微膨胀性抵消碱激发胶凝材料的收缩，从而改善碱激发胶凝材料的收缩性能，制备了适合多孔混凝土道路基层的新型无机胶凝材料。本项目的研究成果改善了碱激发矿渣/粉煤灰胶凝材料的收缩性能，增加了该材料的韧性，并在一定程度上解决了碱激发材料在早期反应放热量大的问题，可为碱激发矿渣混凝土的应用提供理论基础，在碱激发矿渣商品混凝土的应用上具有较强的实用价值和推广意义。