Effect of Supplementary Cementitious Materials on Freshly Mixed Concrete

Effect of Supplementary Cementitious Materials on Freshly Mixed Concrete

Quality Measure vs Effect

Water Requirements : Fly ash reduces water requirements. Silica fume increases water  requirements.

Air Content : Fly ash and silica fume reduce air content, compensate by increasing air entrainer.

Workability : Fly ash, ground slag, and inert minerals generally increase workability. Silica fume                              reduces workability; use superplasticizer to compensate.

Hydration :  Fly ash reduces heat of hydration. Silica fume may not affect heat, but superplasticizer                         used with silica fume can increase heat.

Set Time : Fly ash, natural pozzolans and blast furnace slag increase set time. Can use accelerator to                     compensate.