INGREDIENT PERCENTAGE USE EXCESS LACK LIME 60-65 STRENGTH Unsound, disintegration of cement. Low strength, decrease setting time SILICA 17-25 STRENGTH High strength, increase setting time Low strength, decrease setting time ALUMINA 3-8 SETTING TIME Decrease setting time, decrease temperature of clinker Increase setting time IRON OXIDE 0.5-6 COLOUR Reddish color Low hardness MAGNESIA 0.1-3 COLOUR Yellowish color Low hardness GYPSUM 1-3 SETTING TIME Increases setting time Decreases setting time SULPHUR 1-3 SOUNDNESS Unsound Unsound ALKALI 0.1-1 Efflorescence