Civil Engineering July 2022 | Vol 30 No 6

This is prevalent across both public and private development projects. Surprisingly, even consultants seem to be embracing this concept,” says Bhoora. To provide context, from an aggregate perspective, the ‘blue’ material, the com- petent rock mined from below the surface, has always been specified for infrastructure projects because of its high compressive strength. However, the industry is blending the competent rock with overburden type aggregate, which is often referred to as the ‘brown’ material. This has given birth to new product specifications such as G4A or G4B, says Bhoora. “The practice of blending material has become prevalent as contractors become ‘innovative’ by specifying products that will somehow do the job, but coming at a lower price,” he says. The trend has given rise to illegal mining, because there is less processing required when it comes to brown mate- rial. Normally, it’s just free dig material with no need for drilling and blasting. Contractors are therefore taking the borrow pit route, which they believe is the cheaper way of accessing material. That is a big challenge for legal operators who stick to the rules and do everything by the book. Compliance by its nature costs money, and a lot of it, Bhoora adds. This trend is also prevalent in the readymix concrete space. Proof that some contractors are ‘buying down’ on quality is the decline in the average strength of con- crete that AfriSam has been asked to supply by some customers in recent years. “Traditionally, we have always special- ised in the premium product range, which is anything from 35 MPa and above. Today, most of the demand in readymix concrete is for below the 30 MPa product. That, together with the growing requirement for blended material in aggregates, is a clear indication that the premium product market has taken a big blow because of reduced affordability,” explains Bhoora. REPUTABLE SUPPLIER However, he warns that ‘cheap’ construc- tion materials don’t necessarily result in savings in the long run. In fact, inconsis- tency of physical and inherent aggregate properties can result in additional costs of the project. Using the right materials in accordance with the design brief avoids the need for future costly and unsched- uled corrective works, which can result Civil Engineering July 2022 5 With AfriSam, customers can rest assured that quality is consistent across the entire value chain Material testing is a must in construction, especially in road projects Inconsistency of physical and inherent aggregate properties can result in additional costs