Points to ponder before adding additives to plaster

摘要

The properties of plaster in both fresh and hardened states depend to a large extent on the properties of the materials used. This article discusses the role of additives in plaster, and factors to bear in mind before specifying their inclusion. Hydrated builder's lime - both calcitic lime and dolomitic lime - are available in South Africa, depending on location. Builder's lime must comply with SANS 523 (type A2P) and is used to improve workability, plasticity and water retentivity of mortars and plasters. Up to one bag (25 kg or 40 litres measured loosely) may be used per bag of common cement. The quantity added depends largely on the fines content of the sand, but builder's lime should not be used with masonry cement.