The feasibility of sulphoaluminate cement （SAC） utilization in support mortar was studied. Setting time and strength of as-received sulphoaluminate cement （SAC） paste were examined, hydration kinetics behavior was determined through Isothermal Calorimeter, and hydration mechanism was investigated by X-Ray diffraction analysis （XRD） and field emission scanning electron microscopy analysis （FSEM）. Results showed that as-received SAC contained 61% of anhydrous calcium sulfate （3CA＇CaSO4） and dicalcium silicate （C2S）. The strength after 1 day or 3 days grew to 68.6% or 85.7% of that after 28 days respectively, while most of hydration heat was released within 1 day. The emergency of three exothermic peaks at acceleration stage was found and hydration kinetics model was established choosing the terminal time of the first exothermic peak at accelerating stage as the beginning of accelerating stage. XRD analysis suggested that large amount of ettringite （AFt） was produced at early age and FSEM observation revealed that ettringite （AFt） formed in sulphoaluminate cement （SAC） paste was characterized of different morphology which was proved to be caused by different ion concentrations.
In this paper, we investigates the concretes respec- tively incorporated with 5% （m ： rn） nano-SiO2 （NS）, 40% （rn ： m） super- fine slag （SS）, as well as 40% （m ： m） SS combining 20% replacement of sand volume with RP. The tested mechanical properties include compressive strength, abrasion resistant strength, and elastic modulus. The results indicate that among these concretes, the SS-RP concrete has the highest abrasion re- sistant strength with increment ratios of 1.71 and 1.35 at 28 days and 90 days, respectively; the SS concrete has the highest com- pressive strength with increment ratios of 2.03 and 1.95 at 28 days and 90 days, respectively; the elastic modulus of SS-RP concrete significantly decrease compared with the SS concrete and is slightly higher than that of the reference concrete. It is concluded that NS, SS, and RP all can improve the abrasion resistance of concrete, and it will be significantly improved when SS combining RP is incorporated.
