Introduced on a massive scale in 20th-century construction for its rapid setting and unequalled strength, cement render replaced lime as the standard coating for modern buildings, offering a rigid armour against impacts and weathering.
The mix is based on the use of Portland cement as the exclusive or predominant binder, combined with siliceous or calcareous sands and water-repellent additives. Unlike the slow carbonation of lime, cement hydration ensures rapid curing and compressive strengths (classes CS III or CS IV) that easily exceed 10 MPa. This makes it the ideal render for receiving heavy coverings bonded directly to its surface.
Cement's strength is also its architectural limit. The very high density of the matrix creates a barrier with low permeability to water vapour (high mu). While this is perfect for protecting plinths and basements from driving rain, it is lethal on historic masonry or porous brickwork: rising damp, blocked by the cement render, accumulates at the interface, causing hydraulic and saline stresses that lead to uncontrolled detachment of the finish.
Standards
European and international references applicable.
Physical properties
Usage environment
Cement plaster is not recommended on historical stone or solid-brick masonry: its low vapour permeability traps rising damp, generating hydraulic and salt stresses that cause plaster detachment.