Carl Bierman, BVi Consulting Engineers
SPEAKER PRESENTATION
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The development of cold recycling technology using bitumen stabilisation is driven by ever-increasing economic and environmental pressures. The first best practice manual focused on foamed bitumen technology, the original TG2, was released in South Africa in 2002. This document provided a standardised methodology for mix design, structural pavement design and construction of foam bitumen treated materials.
The second edition of the TG2 was published in 2009, introducing a generic guideline for Bitumen Stabilised Materials (BSM) produced using either bitumen emulsion or foamed bitumen. In addition to providing a robust guideline for the industry, TG2 2009 also identified the shear properties of BSM as the key performance indicator.
Since 2009, researchers have interrogated data from more than 300 BSM mix designs and 69 long-term pavement studies. These considerable studies have led to developments in the performance properties of BSMs, a refined mix design process and improved pavement design methods. The latest TG2, published in August 2020, incorporates the previous decadeās research. The existing Pavement Number heuristic design system was further calibrated, and a mechanistic design function was developed specifically for BSMs. The improved design methods for BSMs allow the effective design of long-term road recycling solutions with many environmental and economic benefits.
This study covers the evolution of the structural design methods for BSM through an increased understanding of the material behaviour. Focus is placed on the various factors influencing the long-term performance of BSM and how they are incorporated into the latest design function.
About the Author
Carl Bierman graduated from Stellenbosch University with a Civil Engineering degree in 2016, and a Masters in Pavement Engineering with a focus on the design of Bitumen Stabilised Materials (BSM) in 2018. He went on to spend three years learning the ins and outs of the construction industry with Roadmac Surfacing Cape, and then moved to BVi Consulting Engineers Western Cape, where he works as an Assistant Contracts Engineer and a BSM application engineer.
