Chemical activation of blended cements made with lime and natural pozzolans

This paper deals with the chemical activation of lime-pozzolan cement (LPC), which consists of 80% natural pozzolan and 20% hydrated lime (by mass). Results show that the addition of 4% Na₂SO₄ can significantly improve the early strength of this cement. The presence of 4% flake calcium chloride (CaCl₂.2H₂O) is not helpful to early strength, but can increase the later strength substantially. CaSO₄.O.5H₂O and NaCl do not demonstrate an obvious effect on the strength development of the cement. Combination of activators, such as CaCl₂.2H₂O+Na₂SO₄ or Na₂SO₄+NaCl does not improve the activation effect; pastes with 2% Na₂SO₄+2% NaCl show lower strength than the pastes with 2% Na₂SO₄ alone.