As a leading supplier of cement, aggregate and readymix concrete products, AfriSam’s focus is on quality control and the ongoing monitoring of its products’ performance, providing a foundation of trust for customers. This means ongoing process control testing of products produced by SA’s leading construction material supplier.

Amit Dawneerangen, GM: Readymix at AfriSam, says test results are closely monitored for deviations beyond preset tolerances. “We analyse results to identify trends so that action can be taken timeously and products can be improved continuously,” he explains.

Among the quality control facilities are the plant laboratories based at AfriSam’s cement, aggregate and readymix operations around the country. At the cement laboratories, routine chemical and physical tests are carried out on raw meal, on in-process material and on the final product, allowing production staff to control cement quality during the entire process.

This complex chain extends from the selection of blast sites in the quarry to raw meal proportioning, adjustment of kiln temperatures and grinding parameters, blending proportions, and the final product. In the aggregate laboratories, samples are taken regularly and subjected to grading analysis and, in the case of stone, to flakiness index testing to ensure that no non-conforming aggregate leaves the quarry or crushing plant.

“This is vital to the customer, as grading and density results form the basis of concrete mix designs and their performance,” Dawneerangen says. To ensure trust in its laboratory testing, AfriSam’s Centre of Product Excellence (CPE) laboratory complies with ISO 17025, which governs requirements
for the competence of testing and calibration laboratories.

At its readymix plants, AfriSam laboratories conduct slump tests on samples of concrete leaving the plant to check that the workability of the material is in line with customer requirements. Cubes are made up for testing compressive strength to ensure ongoing compliance with strength requirements. Any non-conforming results are reported immediately to management for in-depth investigation.

Active quality monitoring

Underlying the organisation-wide commitment to quality are cutting-edge resources like AfriSam’s cement monitoring programme, where process control test results from all AfriSam plant laboratories are captured.

An electronic monitoring report correlates all results and gives managers immediate access to trend analysis reports. This allows empowered decisions concerning raw meal proportioning to ensure that the required
performance criteria are always maintained.

Key to the focus on quality is AfriSam’s CPE, based in Roodepoort, Gauteng. The CPE supports the company’s business units and customers with extensive quality assurance services. With its chemical, physical and materials laboratories, it is well equipped to carry out a wide range of tests on cements and concrete, including mix optimisation and durability index testing.

Developing and testing products to comply with specialised application requirements and project specifications, the CPE also conducts analyses and forensic investigations into situations where concrete does not achieve the performance characteristics for which it was designed.

To assist with the design of mixes, CPE has consultants available countrywide who can troubleshoot and conduct technical assessment of materials and processes at a customer’s site. Where necessary, these consultants arrange for trial mixes and other testing services to be carried out in controlled laboratory conditions at the Roodepoort facility.

Value-adding research

By investing in the expertise and systems that sustain quality products, AfriSam is also well positioned to conduct and coordinate valuable research into the properties of cements, supplementary cementitious materials, aggregates and concrete. These research projects are initiated and rolled out in collaboration with customers, universities and other bodies.

Research projects that are currently under way include a long-term assessment of the effects of highly corrosive environments on concretes made with differing proportions and types of raw materials. Results from these tests feed into dedicated computer software that allows architects and contractors to specify the appropriate grade of concrete to suit their project’s environmental conditions.

Proactive monitoring, while part of its quality control function, also forms an important part of AfriSam’s product development cycle, giving it the scientific and experiential basis to constantly develop new innovations to add to its extensive range of offerings.

Cementing AfriSam’s lead

An example has been AfriSam Rapid Hard Cement, which is ideal for a range of applications. For precast concrete, for example, it allows for faster demoulding times; while in a fast-track construction project, it can facilitate the early stripping of formwork, early bridge launching or higher sliding rates. It can also be used for post-tensioned and prestressed members.

AfriSam Rapid Hard Cement exhibits faster strength development due to the cement being manufactured to a carefully controlled fineness together with a performance modifier to further enhance this feature.

It is ideal for cold-weather concreting where the high early liberation of heat due to hydration can offset the retardation effect of low temperatures. Where durability is important, AfriSam Rapid Hard Cement can be further blended on-site with ground granulated blast furnace slag, fly ash or condensed silica fume.

Other cement innovations include AfriSam High Strength Cement, a specially developed composite cement for use in the manufacture of bricks and blocks, as well as for reservoirs, precast operations, structural concrete, shotcrete and mining operations. The strength development of this cement is more than sufficient to allow for the normal progress of building operations and is ideal for use in specialised applications.

AfriSam Roadstab cement is another engineered composite cement used specifically in road stabilisation, ensuring uniform distribution of the stabilising agent throughout the stabilised layer and giving the bound material significant strength to improve the durability of road sub-bases. Effective across a broad range of road material types, AfriSam Roadstab reduces the plasticity of the soil and adds strength.

In line with Afrisam’s quality and safety commitments, all cement operations have ISO 14001 and OHSAS 18001 certification.

Rock solid performance

One of the country’s largest suppliers of quality aggregate, AfriSam has the capacity to produce over 10 Mt of aggregate per annum from its quarries and crushing plants in Gauteng, Mpumalanga, KwaZulu-Natal and the Western Cape. All these operations – as well as their plant laboratories – have ISO 9001 certification, ensuring that all stone is fully compliant with the relevant specifications and customer requirements.

The product range covers every need in the aggregate field. Roadstone is supplied to the specific grading, shape and wearing properties required for asphalt and road surfacing applications, while concrete aggregates include a wide range of stone sizes within target gradings – as well as washed and unwashed crusher sands for use in all on-site and readymix concrete applications.

Material is supplied for road layer works, such as the base and sub-base materials that provide the interlocking support structure in road design, with different categories of graded material catering for varying load designs. AfriSam also supplies speciality aggregate, including railway ballast, gabion and other larger-sized crushed stone for use in erosion protection, architecture and landscaping.

Ready to roll

With more than 40 readymix plants in Gauteng, Mpumalanga, North West, KwaZulu-Natal and the Western Cape, AfriSam offers customers the competitive edge in construction. Here, the offering extends beyond the choice and proportioning of suitable and compliant raw materials to computerised weigh-batching, concrete pumping services, technical backup and quality assurance.

All the readymix plants have ISO 9001 certification and offer mixes for a wide range of applications, from foundations and pillars to suspended slabs and surface beds. They also produce speciality mixes such as high-spec durability-grade concrete, self-compacting concrete, flowcrete and fibre-reinforced concrete.