Ingredients of Cement

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

Dry weight of sand mortar

Mortar is heterogeneous mixture of cement sand and water. Water reacts chemically with cement ingredients resulting in hydration of cement and fills the voids between cement and sand. As water is added to dry cement sand mixture the volume reduced. For quantity estimate of cement sand mortar the wet mortar’s volume should be increased to account for Water required for hydration. Water required filling of voids. Dry weight of mortar = Wet weight of mortar * 1.33