Preparation of tubular hierarchically porous silicate cement compacts via a tert-butyl alcohol (TBA)-based freeze casting method

• Tubular porous silicate cement compact with hierarchical porosity were fabricated via a TBA-based freeze-casting.
• Highly ordered and unidirectional prismatic pore structures were observed.
• Tubular porous silicate cement compact showed both considerable flux rate and desirable selectivity.
• Curing process is a non-cost and environmental-friendly method for porous cementitious material.
• The method can be employed to prepare many other cement-based porous materials.

Tubular porous silicate cement compacts with hierarchical porosity were successfully fabricated via a tert-butyl alcohol (TBA)-based freeze-casting technique in one single step. These samples were characterized by unidirectional aligned pore channels and completely open porosity. Various experimental parameters affecting the macropore size, mesopore size, porosity, and compression strength were investigated, including the initial solids loading, freezing temperature and curing period. Both the research findings of microstructure observations and property tests show that the pore size decreased significantly with decreasing freezing temperature and increasing solids loading. The porosity increased significantly with decreasing solids loading, while the compressive strength decreased remarkably. In addition to their tunable physical characteristics, these brand-new inorganic porous materials with oriented aligned pore channels and dense layer surface showed high permeation performance and desirable separation ability. These results endow the silicate cement, a kind of low-cost and high-performance architecture material, with great potential as a novel ordered porous inorganic material for numerous applications, especially in separation process.

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