ABSTRACT
An alternative and very common means of improving the workability of cement-sand mixes, and thereby reducing their cement content, is by the use of plasticizers which entrain air into the mortar. Today, mortar is usually required to bond and distribute loads between separate walling units so they act structurally as brick, block or stone masonry. To some exent, colour of mortar results from that of the sand, but it is mainly due to that of the cement, whether grey, white or coloured. Sulphate-resisting Portland cement can be required to provide superior resistance to attack by sulphates, eg those in sulphate-bearing soils or in clay bricks, although the added sulphate resistance afforded to lean mortars may be negligible. In drying, Portland cement and lime shrink, and in particular Portland cement tends to crack. To avoid expansion of mature mortar, slaking of lime must be complete before it sets and loses its plasticity.
