Abstract: Dolomite was modified through calcination mixed with muck. The effects of calcined muck-dolomite on the strength and expansion properties of cement mortar were investigated. The hydration products of cement containing calcined muck-dolomite were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Results show that β-C2S and C12A7 were generated in calcined muck-dolomite, and the content of β-C2S and C12A7 increased with the rising of calcination temperature. The incorporation of calcined muck-dolomite improves the strengths of blended cement mortar effectively at later age. Cement mortar containing 10% calcined muck-dolomite even gain a higher strength at 90 d than pure cement mortars. In addition, the hydration of MgO in calcined muck-dolomite gave rise to Mg(OH)₂, resulting in the expansion of cement mortars, and the expansion rate augmented with the increase of dosage of calcined muck-dolomite. The research finding is of referential value for promoting the application of dolomite in cement concrete and for reducing the pollution of construction wastes.

Key words: muck, dolomite, calcination, strength of cement mortar, expansion properties