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13 November 2023

The South African concrete industry should pay more attention to updating concrete mix designs to further improve both the sustainability and resilience of concrete, says Bryan Perrie, CEO of Cement & Concrete SA (CCSA).

Perrie was speaking at the recent ConPaveStruc 2023. the first National Conference on Concrete Roads and Allied Structures, held recently as a collaborative event between Cement & Concrete SA (CCSA), the Council for Scientific and Industrial Research (CSIR), the SA Road Federation (SARF) and the SA National Roads Agency (SANRAL). The event was seen by more than 900 delegates online, with another 120 attending in person in Pietermaritzburg.

The 25 presentations at ConPaveStruc 2023, focusing on the themes of Chemistry for Cement & Concrete, Pavements, Structures, Tunnels and Barriers, highlighted developments in cementitious materials, showcased current projects in South Africa, and presented international case studies and insights.

Perrie told the delegates that concrete is the most sustainable, resilient choice for both pavements and structures but concrete designs should incorporate latest techniques, materials and test methods. “There are numerous ways to decrease embodied and long-term environmental impacts and it has become essential to take full consideration of concrete mix designs to further improve both sustainability and resilience while minimising carbon emissions,” he stated.

Perrie said:

  • Designs should optimise material usage;
  • Reduce CO2 emissions;
  • Ensure optimised aggregate grading and therefore cement content; and
  • Use appropriate test methods.

“When it comes to optimising designs to minimise material usage, the onus is on designers to look carefully at their designs, using the most up to date design tools methods and that the best and most suitable materials are incorporated. The cheapest materials often result in more expensive concrete.

“Gradings should also be optimised to ensure maximum packing and minimum paste content, and designers should consider the benefits of extended cements, placeability, and consider and assess early age shrinkage and cracking,” Perrie advised.

He said CCSA Partners have committed to Net Zero Carbon by 2050 and local cement standards now allow wide range of cements that should be considered by mix designers. New aggregate specifications should also be considered.

Perrie again emphasised the immense importance of concrete structures and concrete roads’ resilience during severe climate change. This should be a particularly strong factor to consider by decision-makers together with life-cycle cost assessment (LCCA) and life-cycle analysis (LCA) for SA infrastructural development.

“Sustainability is important and deals with known events that can be quantified. Resilience, on the other hand, is the ability to anticipate, prepare for, and adapt to changing conditions and withstand, respond to, and recover rapidly after a disruptive event.

“In a changing global climate where extreme weather events are now becoming increasingly frequent, with far higher intensity than in the past, it is impossible to have a sustainable infrastructure without resilience. Resilient systems limit the impact of relatively unexpected adverse effects such as storms, floods and droughts, such as experienced recently in KwaZulu-Natal and the Eastern and Western Cape. The challenge is how to build more durable concrete structures and pavements while minimising the carbon emissions generated in producing and supplying cement and concrete,” he explained.

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