Influence of flue gas desulphurisation ash on moisture damage in asphalt mixtures

摘要

Moisture damage has a significant negative impact on asphalt and the behaviour of the pavement. It exacerbates the service performance (e. g. rutting, cracking) of the asphalt mixture. This paper investigated the influence of flue gas desulphurisation ash (FGDA) on asphalt mixture moisture damage. First, the properties of FGDA were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence and differential scanning calorimetry (DSC). To investigate the effect of FGDA on moisture damage, the limestone powder (LSP) in asphalt mortars or asphalt mixtures was replaced by FGDA with a volume content of 0%, 20%, 40%, 60%, 80% and 100%. The effects on moisture sensitivity of the asphalt mixture were evaluated by adhesion tests using a modified water boiling method, Marshall stability and indirect tensile strength tests. Results showed that the mortar with 100% FGDA exhibited better adhesion to aggregate than others, and the asphalt mixture with FGDA showed excellent moisture sensitivity in terms of higher retained Marshall stability, indirect tensile strength and tensile strength ratio during freeze-thaw cycles. It is therefore concluded that FGDA can improve effectively the moisture stability of asphalt mixture.