Effect of MgAl-layered double hydroxides on properties of high-iron low-calcium portland cement
MgAl-layered double hydroxides(MgAl-LDH)were synthesized using a separate nucleation and aging steps(SNAS)method,and high-iron low-calcium portland cement(iron phase mass fraction of 19.6%)was prepared by lime-stone,standstone and iron ore powder.The effects of MgAl-LDH content on the chloride curing ability,mechanical proper-ties and microstructure of high-iron low-calcium cement were studied by X-ray diffraction(XRD),thermogravimetric(TG),scanning electron microscopy(SEM),and chemical analysis methods.The results showed that MgAl-LDH could improve the mechanical properties and chemical curing ability of chloride ions.When MgAl-LDH content was 3%(mass fraction),compared with the blank group,the chloride ion curing rate at 7 d was increased by 46.4%,and the compressive strength at 3,7 d and 28 d was increased by 27.5%,34.6%and 17.1%,respectively.The microscopic tests showed that MgAl-LDH could promote the early hydration of high-iron low-calcium cement to generate more hydration products,and promote the densification of cement structure to a certain extent.And it could promote the reaction of hydration products and chloride ions to form Friedel's salt,and improve the chemical curing amount of chloride ions.
MgAl-LDHhigh-iron low-calcium cementchloride bingdingmechanical propertiesFriedel's salt
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