Getting it right the first time

Strict adherence to quality control ensures that construction programmes are completed on time, on budget and within specification. IMIESA speaks to Amit Dawneerangen, GM: Sales & Product Technical at AfriSam, about the key role they play as a construction material supplier.

The road maintenance backlog is growing, and construction costs are escalating. How can AfriSam help fill the gap?

AD AfriSam conducts extensive process control testing on all their products to ensure compliance with the relevant national standards. External testing is also conducted where required, especially on materials for road construction. Globally recognised methodologies include Polished Stone Value, Los Angeles Abrasion, and California Bearing Ratio tests.

For road construction, our quarries manufacture G1 to G7 products for layerworks construction, and these products comply to the Colto specification. At most operations, our stone and crushed sand products are also suitable for use in asphalt production.

Using the right materials in accordance with the design brief avoids the need for future unscheduled remedial works, which can result in substantial additional costs, depending on the nature of the project.

When it comes to aggregates, what are some of the pitfalls to note?

First, cheap aggregate is not necessarily quality aggregate. Inconsistency of physical and inherent aggregate properties is another crucial factor to consider, since the wrong product will result in a subsequent pavement failure.

AfriSam personnel conduct routine physical testing to ensure that material leaving the quarry is consistent, and inherent properties are checked every quarter. In addition, regular quarry optimisation meetings are held to ensure that all technical and production efforts are aligned. For example, benches are classified before each blast by testing the drill chips.

This will establish if there are any hidden issues that may make the material unsuitable for specific products.

It’s also essential to engage only with aggregate quarries that are legally registered to operate by the Department of Mineral Resources and Energy. In other words, quarries must have a valid mining licence and be environmentally compliant. In terms of the Mining Charter, they must also invest in the surrounding community.

Another important point to note is that commercially accredited laboratories do not always yield consistent or accurate test results. That can lead to challenges on projects in terms of acceptance of material supplied. AfriSam’s internal laboratories provide an absolute quality assurance and material guarantee.

What solutions does AfriSam provide for the asphalt market?

Where specialised materials are required for the production of proprietary products, AfriSam has the technical and production ability to partner with our customers to provide solutions.

The AfriSam Technical Reference Guide (8.2 Edition), which can be downloaded from our website, provides typical values for tests such as ACV, 10% FACT, PSV, fine aggregate angularity index and magnesium sulfate soundness, clay lumps and variables, fractured faces, SANS 1083 requirements and sand equivalent.

Should concrete surfaced roads be receiving greater acceptance in South Africa?

The application or prevalence of concrete roads is largely dependent on it being specified by the client/engineer/designer.

The following are some of the advantages of going the concrete route: - One of the greatest is their longevity – concrete roads can last between 20 to 40 years on average, which is two to four times the lifespan of asphalt. - Concrete can be recycled back into roads either by using it in the sub-base layers or by reintroducing it into the new concrete mix.

- For heavily trafficked truck routes, concrete roads are better suited due to their increased durability and resistance to rutting. - In areas where freeze/thaw is an issue, concrete roads are more resistant than asphalt surfaces, which become brittle. - Concrete roads manufactured with a low carbon footprint concrete mix are greener than asphalt. - Vehicles tend to be more fuel efficient on concrete roads than asphalt because of the former’s better resistance to surface flex. - Concrete surfaces reflect light more effectively than asphalt, therefore requiring less illumination at night and thus making it better for the environment. - Asphalt production creates greenhouse gases, which are not environmentally friendly even when using recycled material. - Bitumen production releases hydrocarbons into the environment. - Asphalt roads only have a lifespan of about 10 years before requiring a resurface.

Slipform paving is a standard technique worldwide. Why do you think it’s receiving less attention in South Africa?

Local contractors do possess the necessary skills and equipment to execute slipform paving, but this will depend on the design method chosen. The application of labourintensive construction (LIC) techniques also has an influence. An example is the current N3 upgrade between Durban and Pietermaritzburg, where the initial scope included slipform paving. However, this subsequently changed to the conventional placement of concrete using LIC elements.

What is the role of AfriSam’s Readymix Division within the roads sector?

Our readymix concrete product range is well suited for bridge and related infrastructure. Normally with these types of structures, the project specification defines the mix proportions and performance criteria. This is where our Product Technical Department gets involved to interpret the specification, and design customised mixes to fully comply.

Very often concrete is required to have a minimum binder content or max w/c (water to cement) ratio and meet shrinkage, flexural strength, and durability criteria. Our service offering involves design and laboratory testing of these mixes to ensure compliance prior to supply.

Our product portfolio, plus previous work and experience gained on landmark projects such as the Gauteng Freeway Improvement Project (GFIP) and N7 Cape, positions us to make a meaningful contribution to South Africa’s infrastructure programme.

We are currently supplying concrete to three sections of the N3 upgrade between Cato Ridge and Lynnfield Park. Concrete supplied is being used to construct precast median barriers, V drains and culverts. Later this year, AfriSam will supply road pavement concrete for the Lynnfield Park to Ashburton section. All concrete supplied needs to conform to strict project specification requirements.

Has the decision to make locally produced cement compulsory on public infrastructure projects been successfully applied?

Yes, it has. This will assist in ensuring locally manufactured cement products are used, thereby supporting South African cement companies. However, at the moment, government projects unfortunately form only a small percentage of the overall projects under way in South Africa, and the local industry requires more protection against imports.

And in closing?

AfriSam is invested in South Africa and South African construction. Renewed investment in road infrastructure is long overdue; however, we’re starting to see more Sanral projects coming online, alongside municipal roads projects.

Alongside major upgrades, there’s also a pressing need for widespread road and bridge maintenance – and, here, AfriSam’s basket of services are a fit-forpurpose solution.