Roads and Maritime Services (RMS) pavement specifications require the use of Grade 1 fly ash and Ground Granulated Blast Furnace slag cement (GGBFS) for R82 – lean mix concrete subbase [1], and also fly ash and/or GGBFS for R83 – Concrete Pavement Base [2], where reactive aggregates are used.
This investigation revisits the prior work done in this area by Whitaker [3] and further assesses the replacement of the fly ash in these applications with Ground Granulated Blast Furnace Slag (GGBFS).
In recent times fly ash supply has been less reliable, and the RMS specification 3211 – Cements, Binders and Fillers [4], allows for varying quantities of slag cement as a direct replacement.
Based on laboratory trials, including assessing the concrete properties for plastic cracking potential using ASTM method C1579-13, Standard Test Method for Evaluating Plastic Cracking of Restrained Fiber Reinforced Concrete (Using a Steel Form Insert) [5], this paper assesses the two mixes with alternate supplementary cementitious materials and presents the findings of plastic and hardened properties.
The differences in the two specifications (R82 Lean Mix and R83 Base pavement), and application of the two supplementary cementitious materials, including QA specification 3211, are addressed and comparisons to the actual laboratory mix designs as trialled are investigated.
