Insisting on only accredited readymix suppliers can not only prevent project failures, but it can save lives too.
While anyone can mix and manufacture concrete, it needs to be done in a measurable and sustainable way to ensure consistent quality.
This is according to Johan van Wyk, general manager of the Southern Africa Readymix Association (Sarma). He further emphasises that high levels of technical expertise are also required in order to mix and manufacture more specialised types of concrete, and to ensure products are made to specifications and are fit for purpose.
“Unless standards are specified by professionals, there are no regulations in place to govern the manufacture and supply of quality readymix concrete in South Africa,” Van Wyk adds.
Regulating readymix plants
In an effort to regulate the industry, Sarma has a system in place to audit readymix plants, based on international ISO measures. Van Wyk explains that the system is used for accreditation and ongoing verification through annual audits, both scheduled and unannounced, to ensure standards are upheld at all times.
He outlines some of the procedures Sarma-approved readymix concrete must adhere to before being delivered:
1. Material control is conducted on all raw materials. Cement and extenders need to be SABS-certified, while admixes need to comply with SANS 878, water must be within acceptable limits and aggregates to specification. Material history also needs to be traceable.
2. Once mixes have been set and concrete mixed, the plant will undertake yield testing of a cubic metre of concrete in compliance with SANS 61250 test procedures. Checks are done for masses and densities on aggregate.
3. The means and accuracy of measurement are predefined and need to be carried out according to procedures. All readymix in South Africa must adhere to accuracy level tolerances of 2% for cement, admixtures and extenders, and 3% for aggregates. Moisture checks need to be done and all measuring equipment needs to be calibrated and recorded. Machinery and equipment also need to be maintained and checked to prevent intermingling of materials, leakages, spillages and spoilage.
4. Records must be kept for several years in accordance with legislation. Information required will detail mix designs, moisture readings, slump tests and strength testing results of the concrete. Sampling and testing need to be done according to prescribed procedures. Cast cubes of concrete per batch need to be cured according to standards and records kept for future reference. Other tests may be specified for different types of concrete.
5. Statistics gathered from the manufacturing process should be used to ensure consistent quality and rectify any deviations, as well as to maximise acceptable deviations to improve plant efficiency to ensure the product is competitively priced.
6. All information relating to orders must be recorded to ensure that client requirements are met, as well as any changes required later on. This is in line with the transparency requirements of the association and to minimise conflict at the point of delivery.
“These are just some of the requirements that need to be met for each load of concrete delivered by accredited members,” says Van Wyk.
“The lives of loved ones, quality of life of surrounding communities and success of construction projects may be at stake,” he concludes.
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Caption: Insisting on only accredited readymix suppliers can not only prevent project failures, but it can save lives too.