CONCRETE MIX DESIGNS now more important than ever

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 CCSA, the Council for Scientific and Industrial Research, the South African Road Federation, and the South African National Roads Agency. 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 and 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 says 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 explains.

To achieve this:

• 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 tool methods and that the best and most suitable materials are incorporated. The cheapest materials often result in more expensive concrete,” Perrie explains.

“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.”

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

Sustainability and resilience

At ConPaveStruc 2023, Perrie again emphasised the immense importance of concrete structures and concrete roads’ resilience during severe climate change. As he points out, this should be a particularly strong factor to consider by decision-makers together with lifecycle cost assessment and lifecycle analysis for South African infrastructural developments. www.cemcon-sa.org.za

“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,” adds Perrie.

“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,” Perrie concludes.

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 sustainable infrastructure without resilience

The OVK Group, a leading agricultural company headquartered in Ladybrand, South Africa, has showcased its commitment to progress with the completion of a significant warehouse refurbishment project in Gqeberha, Eastern Cape.