Effect of activation temperature on mechanical properties of red mud-based cementitious materials
In the context of the bulk utilization of solid waste,this paper uses the thermal activation red mud to enhance its gelling activity for preparation red mud-based cementitious materials.The strength of red mud-based cementitious materials and the types of hydration products are characterized and analyzed by uncon-fined compressive strength testing machine,X-ray diffractometer and fourier transform infrared spectrometer.The results show that the mineral phase of the red mud experiencing different treatment temperature are vari-ous.It is in a metastable state with the high activity after 800℃thermal activation,while in a stable state with the low activity after 900℃thermal activation.The 3d and 28d mechanical properties of the cementitious mate-rials prepared with 800℃activated red mud are improved by 64%and 70%compared with that of those with unactivated red mud,and the 28d compressive strength is up to 42MPa.Analysis of the XRD and infrared spectra of the hydration products of cementitious materials show that the mineral phase and chemical groups of the hydration products of cementitious materials doped with 800℃activated red mud are very different from that of those doped 900℃activated red mud.Not only the mineral phase of Fe2O3 weakens,the mineral phases of CaAl2Si2O8-4H2O,Fe2SiO4,and KMg3(Si3Al)O10(OH)2 are enhanced and hematite involves in the hydration re-action,but also geopolymer-like gel substances appears and the occurrence of the maximum degree of hydra-tion reaction results in the generation of dense crystalline bodies,all of which indicate that 800℃is the opti-mal temperature for activated red mud and the why the mechanical properties of the red mud-based cementi-tious materials with 800℃activated red mud is the best.
red mudcementitious materialsolid waste utilizationactivation temperature
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