Coverland, one of the largest concrete roof-tile manufacturers in the country, has strict policies on quality control, health, safety and the environment. This led them to purchasing a water-repellent efflorescence-reducing agent called Chryso®Pareflo 20.
Efflorescence is an aesthetic problem that results in a white, chalky substance that is deposited on the surface of concrete. It is caused by soluble salts migrating through the concrete via capillary action. Once these soluble salts come into contact with air, unsightly white sediment appears.
Although efflorescence is a common, natural phenomenon that does not cause structural damage, and is often removed by the natural process of weathering (like rainwater washing over tiles), Coverland has taken every possible step to counteract it. The organisation prides itself on quality and refuses to give customers blemished products.
Their roof tiles must be flawless, from the time that they come off the production line to the time that they reach consumers. “The problem is that it is during this time that efflorescence most commonly occurs,” explains Willem Grove, the marketing manager of Monier South Africa.
Chryso has developed a concrete admixture that reduces efflorescence and does not affect the mechanical strength of concrete nor entrain any air into the concrete. Chryso®Pareflo 20 is a long-lasting solution that is ideally suited for light precast applications such as roof tiles.
The admixture reacts with the cement matrix, creating a polymer network that fills the capillary holes in concrete. It prevents efflorescence from forming because the soluble salts cannot travel through the capillaries and they cannot crystallise as they do not come into contact with air.
“The traditional approach to prevent efflorescence in the precast industry is acid washing. This is not an ideal option because there are potential health, safety and environmental issues that can arise,” says Grove. He further explains that sustainability is a fundamental part of Coverland. “We aim to deliver sustainable products and systems to our clients while respecting the environment in our manufacturing processes. Chryso®Pareflo 20 has assisted us in adhering to this principle.”
According to Grove, acid washing also slows down the production process of the roof tile. “In contrast, a minimal amount of Chryso®Pareflo 20 is added directly to the concrete mix, making the production process faster and safer. There is also a significant cost benefit involved,” says Grove.
Another important function of Chryso®Pareflo 20 is that it acts as a water repellent because it reduces capillary absorption. Coverland conducts a rain roof test where 16 roof tiles are stacked at a sloping angle, similar to a roof, and have water running down them continuously for two hours. “With tiles produced using Chryso®Pareflo 20, there is a noticeable water-beading effect on the tiles and this helps to ensure that water penetration is kept to the minimum acceptable standards.”
An added benefit of using Chryso®Pareflo 20 is that the tiles are much richer in colour than tiles produced without Chryso®Pareflo 20. “Coverland always strives to create products that have the lowest environmental footprint and the highest quality. Chryso®Pareflo 20 is a way to achieve this,” states Grove.