Call to professionalise concrete supplies
Speakers and participants in the Southern Africa Readymix Association (Sarma) annual conference agreed that more has to be done to ensure that the concrete used on construction sites, albeit for infrastructure or housing etc, needs to be more carefully specified and controlled. This is in order to prevent building collapses and the undue deterioration of structures such as those reported in the media in recent times.
Considering the important role that concrete plays in the majority of our built structures and roads, comparatively few stipulations are put forward by industry bodies for their members to adhere to when specifying concrete. For example, concrete of an unknown origin can be used on most sites as long as it passes a slump test and later on passes strength tests etc.
“But what about the overall integrity of the concrete?” said Sarma general manager, Johan van Wyk. “It is the responsibility of everyone involved in the industry to ensure that this most critical element is properly specified, the correct material is delivered and it is used and cured correctly. That includes the architect, engineers, project manager, contractor and concrete suppliers.
“They all have a role to play and for this reason, the association is leading talks with industry bodies representing diverse professional memberships, including civil engineers, designers, municipal managers, road pavement specialists and civil engineering contractors etc.”
“We want them to make it a requirement of their members to specify concrete only from certified suppliers who comply with national standards relating to the supply of readymix concrete. In addition, the requirement should call for these suppliers to be audited annually to ensure ongoing compliance. They should also be able to prove compliance with environmental and health and safety standards,” Johan added.
He argued that there are hundreds of concrete manufacturing plants out there that have been audited and certified by Sarma and who produce quality concrete. Simultaneously, unfortunately there are also low quality operators (and unscrupulous operators) out there that do not comply with any regulations and who produce thousands of tons of consistently poor quality concrete that is sold and used within the industry every day.”
According to Nico Pienaar, director of two central industry associations responsible for supplying concrete to construction sites, the Aggregate and Sand Producers Association (ASPASA) and the Southern Africa Readymix Association (Sarma), failures are mostly as a result of the “missing critical link” between regulated and unregulated products or scrupulous or unscrupulous suppliers. “Insist on quality cement products from local suppliers and where possible steer away from cheap imported cement and cheap inferior extenders. Concrete is a very sensitive product because it’s made of aggregate, cement and water and extenders and if the ratios and timing is not right it is – simply put – wrong.”
Experts leading a panel discussion on determining the integrity of concrete agreed that consistent quality can only be produced if all the correct ingredients are used and no corners are cut. Ray Bonser, National Product Technical manager for aggregates and readymix at AfriSam, said all the correct elements need to be consistently taken into consideration when making concrete. This includes the use of locally certified cement, quality aggregates that are suitable for the job at hand, as well as the correct mixing which should be done under the supervision of experienced and qualified employees.
Jacques Smith of Go Consult agreed, saying that a weak link anywhere in the process – right up to the proper laying and curing of concrete can be disastrous with potentially dire results for either the end-user, developer, contractor or readymix company (or all of them) in the event of a failure. Dealing with a properly accredited and certified supplier with the correct testing equipment and facilities was the safest and most proactive way of ensuring that a quality product will be delivered every time.
NPC Cimpor general manager, Kevin Quayle, stated that independent laboratory tests in Kwa-Zulu Natal conducted on “cheap” imported cement had found that many of the bags sold were either underweight or simply did not meet strength requirements. “This is an example of how concrete suppliers may try to cut costs and in the process, ruin the overall integrity of the concrete that they supply.”
Another speaker, Marius Grassman of Concrete Testing Equipment, agreed, saying that testing raw materials used in the manufacture of concrete, as well as the end-product, provides concrete manufacturers and users with a valuable tool to ensure quality and provide a record of proof if needed in future.
The laboratory is possibly the most important part of setting-up a readymix plant and is, sadly, the last thing most people think of when starting a plant. Professionals need to not only make sure that they correctly specify concrete, but they also need to test it and make sure it conforms with their requirements – from the types and grades of aggregates used, to the quality of cement, mixtures and final pouring of cement.
Everything should be documented and checked to ensure that the correct concrete is being used.”
Sustainability is key
Another equally important aspect was that of sustainability of both the concrete and the construction industries. Keynote speaker, Jason Drew of AgriProtein Technologies said that it was vital for all industries to innovate and find better solutions to current problems.
His fly breeding program, for example, looked at the problem of waste blood from abattoirs and turned it into a thriving business supplying protein to fisheries while removing the environmentally harmful blood waste from the environment. Similar innovations in the concrete and building industries may remove waste from the system or find alternative dwelling structures to meet the needs of the planet’s growing population.
Monty Olivier of Sustainable Green Consulting added that companies in these industries could also add to the future sustainability of the environment by following a “green path” which included recycling and seeking more energy efficient alternatives to their processes, as well as seeking energy efficiency and recycling alternatives in offices and factories etc. All staff members should be made aware of the importance of environmental issues especially when considering that the world is running out of resources like oil and water.
Source : Leading Architecture and Design and www.aspasa.co.za