Coverland is the South African brand of the global Monier Roofing corporation and, in line with its strict policies on quality control, health, safety and environmental protection, the concrete roof tile manufacturer has decided to include the Chryso water repellent and efflorescence-reducing agent, Chryso®Pareflo 20, in its concrete mix.
Efflorescence is caused by soluble salts migrating through the concrete via capillary action and once these salts come into contact with air, they form a white, chalky deposit on the surface of the concrete.
Willem Grové, marketing manager of Monier South Africa, says, “Although efflorescence is a common and natural phenomenon that does not cause structural damage and is often removed by the natural process of weathering, Coverland has taken every possible step to counteract it. Coverland prides itself on quality. Our roof tiles must be flawless – from the time they come off the production line to the time they reach our customers.
“It is during the week that it takes for the concrete roof tiles to cure that most efflorescence typically occurs,” Grové adds.
Chryso has developed Chryso Pareflo 20 as a concrete admixture that reduces efflorescence and does not affect the mechanical strength of concrete nor entrain any air in the concrete. It is a long-lasting solution ideally suited to light precast applications such as roof tiles. The admixture reacts with the cement matrix, creating a polymer network that fills capillary holes in concrete. This prevents efflorescence because the soluble salts cannot travel through the capillaries and, without contact with air, they cannot crystallise.
“The traditional approach to preventing efflorescence in the precast industry is acid washing,” says Grové. “This is not an ideal option because there are potential health, safety and environmental issues that can arise.
“Acid washing also slows down the production process whereas the addition of a minimal amount of Chryso Pareflo 20 directly to the concrete mix makes production of the roof tiles faster and safer. There is also a significant cost benefit,” says Grové.
Chryso Pareflo 20 also acts as a water repellent and has the added benefit of making the roof tiles much richer in colour than tiles produced without it in the concrete mix.
“As the oldest manufacturer of concrete roof tiles in South Africa, Coverland strives to create products that have the lowest environmental footprint and the highest quality. Chryso Pareflo 20 has helped us achieve this,” Grové says.