The use of geopolymer cement for road surface applications

Abstract

This research considered the use of geopolymer cement technology in innovative road pavement surface applications. Based on reported road traffic collision statistics and assessment of the UK road network condition, two potential applications were selected for consideration: calcined bauxite alternative in high friction surfacing applications and rapid geopolymer road repair materials. A range of geopolymeric materials were used including BanahCEM, metakaolin, GGBS, fly ash and silica fume to produce geopolymer mortars. Investigations into these mortars yielded positive results confirming reported relationships between the performance properties of geopolymer mortars and mix design variables. It was discovered that increasing calcium content resulted in quicker setting times, greater flow values and improved early strength development. Novel geopolymer mortars were produced using iron silicate fines, yielding positive strength properties but less favourable setting times. Geopolymer mortars with suitable setting time and early strength development properties were selected for assessment in rapid road repair applications. Test specimens were subjected to simulated trafficking conditions on the Ulster University road test machine (RTM) to assess performance. It was found that material durability and skid resistance properties were encouraging, but repair material shrinkage posed issues regarding in-service use of geopolymer repair materials. Durability properties of these materials were previously unknown. A range of synthetic, polish resistant geopolymer aggregates were produced, followed by modified polished stone value (PSV3) and micro-Deval (MMD) testing. PSV3 values were encouraging but poor relationships were observed between PSV3 and MMD. Selected aggregates were subjected to simulated trafficking conditions on the RTM. Tested geopolymer aggregates fell short of BBA skid resistance requirements but exceeded texture depth requirements, suggesting good durability of the materials. Two methods were considered to improve the performance of geopolymer aggregates with both yielding improved geopolymer aggregate performance. Two blended aggregates achieved BBA classification. Although increased grit contents resulted in improved performance, SRVs fell short of BBA/HAPAS requirements. Non-contact 3D modelling and analysis methods were applied to consider the relationship between aggregate particle shape and SRV changes during wearing. Strong relationships were observed, suggesting that aggregate shape has an impact on the performance of geopolymer aggregates.

Date of Award	May 2018
Original language	English
Supervisor	Bryan Magee (Supervisor), Svetlana Tretsiakova (Supervisor) & David Woodward (Supervisor)