Cement & Concrete SA (CCSA) has published a special informative leaflet stressing the importance of using the correct and legitimate cement for new structures to prevent building collapses and potential lethal accidents.
“Know Your Cement – In the Interest of Safety” was produced because CCSA says many secondary blenders and unscrupulous importers are selling non-compliant cement, specifically in rural areas, and such structural failures are increasingly happening.
Matthews Magwaza, lecturer at CCSA’s School of Concrete Technology says after a house recently collapsed in Johannesburg’s Western Areas, tests showed that the strength of the foundation had only been 3MPa instead of the required 15MPa.The builder had used incorrect or inferior type of cement, or an incorrect concrete mix, for the foundations. Uncertainty about the different cement types, or when dishonest contractors and builders are using the wrong or non-compliant cement and do not follow the correct mix proportions for a specific project, can be potentially life-threatening,” Magwaza warns.
He says any project that involves concrete starts with the purchase of the correct cement. There are two main types of cement commonly sold in South Africa:
Masonry cement which should only be used for mortar and plaster. These bags have “MC” printed on it and should have the printed wording: “Masonry cement intended to be used for preparation of mortar and plaster only”.
Common cement which must be used for all structural concrete and may also be used for mortar and plaster. These bags must have “CEM” printed on it.
Magwaza explains that says SA cement is regulated by a compulsory standard (VC 9085) administered by the National Regulator for Compulsory Standards (NRCS). This means by law cement must meet certain performance specifications. and adhere to rules for the markings on the bags, to protect human health and safety.
“One of these rules is that specific markings must appear on every bag sold in SA to give the customer peace of mind about the quality and correct application of the cement. Most importantly, an LoA (Letter of Authority) number should be printed on the bag. Unfortunately, an LoA number appearing on the bag is no guarantee that an LoA has been issued so when buying cement from an unknown source, the purchaser should always contact the NRCS on telephone 012 482 8700 to confirm whether the printed LoA is valid.”
CCSA strongly believes the use of SANS-compliant cement and masonry cement is important to:
- Build quality safe structures and buildings;
- Ensure that the user does not break SA law; and
- Prevent liability claims that could follow failures when a cement without a valid LoA was used.
The full leaflet, “Know Your Cement – In the Interest of Safety” can be downloaded free of charge from the CCSA website www.cemcon-sa.org.za.