Effect of SCMs on the freeze-thaw performance of iron-rich phosphoaluminate cement

Due to the low durability of ordinary Portland cement (OPC), the deterioration of OPC-based materials is very severe in marine structures exposed to cold weather. In contrast, iron-rich phosphoaluminate cement (iron-rich PAC) has good durability and is promising for applications in marine construction. In this context, in the present study, the freeze-thaw (F-T) performance of iron-rich PAC mortar was evaluated and compared with those of OPC and sulphoaluminate cement (SAC) mortars. In addition, the influences of supplementary cementitious materials (SCMs), such as fly ash (FA), limestone powder (LP) and gypsum (GP), on the F-T behaviour of the blended iron-rich PAC mortar were carefully investigated by testing the compressive and flexural strengths, analysing the pore structure using mercury intrusion porosimeter (MIP), and examining the microstructure using XRD and SEM-EDS analysis. The experimental results elucidated that the F-T performance of the iron-rich PAC mortar was far better than those of the OPC mortar and the SAC mortar. In the SCM blended iron-rich PAC systems, the most favourable modification results were obtained with replacement by LP at the optimum dosage of 3-9% (wt%). In this replacement range, the F-T resistances of the LP blended iron-rich PAC systems were better than that of the reference PAC (without SCMs). Further, the F-T performances of the FA and LP blended iron-rich PAC systems were superior to those of the OPC and SAC systems. (C) 2019 Elsevier Ltd. All rights reserved.