Successful plastering is very critical in building work whether for decorative or protective coating purposes. Sand- cement plaster is common in concrete and masonry walls and ceilings. In the selection of materials it is important to take into account the mixing proportion, surface preparation and the right process to apply plaster.
Guidelines in the selection of plaster in its fresh and hardened state
- Plaster in its fresh state must be workable and cohesive. During its hardened state, plaster must be strong enough to hold paint and to withstand impact and abrasion. It is also important to ensure that plaster will efficiently bond to the substrate with an acceptable surface texture. In a plane or curved surface, plaster must have an acceptable surface accuracy.
- The hardened state of plaster depends a lot on its fresh state, the substrate and the skills or workmanship of the plasterer.
- Sand is the major component of a plaster mix. It has a significant effect on the performance of the plaster as well as material cost. There are different sources of sand like river, pits and dunes but it is important to ensure that sand is free from any organic materials like roots, twigs and humus.
- The important properties of sand include clay content, grading, maximum particle size and shape. However, it does not mean that when sand meets the standard requirements, it will produce a satisfactory plaster although there is a high probability for an acceptable mix.
- It is important for sand to have continuous grading from dust to large particles since it will significantly affect water requirement, workability and water retention of the mix. Sometimes, there is a need to increase water requirement to improve workability and water retention.
- If there are large particles of sand, they must be removed through sieving to ensure a smooth texture particularly for decorative purposes.
A successful plastering job requires proper choice for bonding agents and mixing proportions as well surface preparation. To ensure the highest quality of workmanship, do not hesitate to call Plasterers in Sydney who have years of building experience. They are totally committed to providing excellence and perfection in any project undertaken.