Impact of GGBFS Cement on the Interfacial Transition Zone and Influences on Flexural Strength of CRCP Concrete

With an increased focus on sustainability of concrete in commercial and infrastructure projects, the use of alternative cementitious sources is increasing. At the same time the availability of flyash in Eastern Australia is becoming less certain and secure in terms of both quality and future quantity. Transport for NSW specification R83 Base Concrete allows for the use of ground granulated blast furnace slag (GGBFS) and includes allowance for the increased shrinkage generally associated with GGBFS. It does not however consider the increased flexural strength associated with GGBFS inclusion in a concrete mix. Hocking et al [1,14] found that flexural strength of paving concrete containing GGBFS concrete was increased by 30-60% compared to a conventional flyash mix. This improved flexural strength exceeded the maximum allowed for Continually Reinforced Concrete Pavement (CRCP). Further work has been completed with a focus to understand the influences to reduce the flexural strength in GGBFS systems. This is discussed in the context of other international specifications and guidelines and the impact it may have on the sustainability credentials and thus use of CRCP for road construction.