Final answer:
Rendering is the process of applying mortar or cement plaster to a block wall, improving appearance and providing water resistance and insulation. It's part of a broader category of construction techniques, distinguishable from troweling, grouting, and pointing.
Step-by-step explanation:
The process of spreading mortar or cement plaster over the block wall is known as rendering. This process involves the application of a premixed layer of sand and cement to brick, concrete, stone, or mud brick. Rendering is used to improve the appearance of a building and provide better water resistance and thermal insulation. The process begins with the preparation of the surface, cleaning it of any dirt, oil, or loose particles. A layer of mortar is then applied to the surface using a trowel. After application, the mortar can be textured or smoothed to achieve the desired finish.
Rendering is distinct from other processes such as troweling, which is simply the action of smoothing out the mortar or concrete; grouting, which involves filling the gaps between tiles; and pointing, which is the final stage in masonry construction that involves applying mortar into the joints of brick or stone structures.
Concrete, which was a Roman invention, is a notable material in rendering and construction. It is a mixture of lime mortar, pebbles, sand, and water that hardens to function like stone. The Romans enhanced mortar by adding volcanic Italian sand, known as "pozzolana", which resulted in incredibly strong and durable construction material. These materials are essential in creating structures since concrete takes the shape of the mold it is poured into, thus enabling the creation of fluid and creative shapes in buildings.