Effect of waste aluminosilicate material on cement hydration and properties of cement mortars

The effect of waste material (catalyst used previously in catalytic cracking of petroleum in fluidized bed—fluidized bed cracking catalyst denoted as FBCC) on cement hydration kinetics was investigated in terms of fineness of this admixture. The compressive strength and microstructure of cement mortars were also examined. Variable percentage of this aluminosilicate admixture, originating from batches of quite different grain size composition, was introduced to cement pastes. Further on, cement mortars were produced using the material of higher activity, as it has been found in admixtured cement investigations. The waste was added as cement replacement or, partially, as sand replacement. The activity of waste catalyst was strongly related to the fineness—finer grains indicate better activity. In the presence of a FBCC admixture, the Ca(OH)₂ content decrease in cement pastes due to the pozzolanic reaction is observed. The surface area of hydrated paste becomes higher and, simultaneously, the mean pore diameter decreases, as compared to reference sample, without admixture. The strength improvement is observed particularly when the aluminosilicate material is introduced as partial sand replacement.