Using waste poplar to replace nonrenewable MgO in cement-based composites

Waste poplar powders with dosage of 0%∼25% of MgO’s mass were mechanically mixed with magnesium oxysulfate cement to prepare new composites. The slurry fluidity, mechanical strength, water resistance and microstructure were studied. The optimal poplar powder dosage as 20% of MgO’s mass was determined based on seven indexes. The flexural strength and compressive strength of the optimal composite at 100d was 17.97 MPa and 62.51 MPa, with flexural strength improvement by 52% comparing to cement matrix. Softening coefficient of the optimal composite was 0.83, showing good water resistance. The optimal composite with 20% poplar powder presented maximum displacement of 0.514 mm and energy absorption capacity of 1.204 J before fracture, which improved by 153% and 209% comparing to cement matrix. The incorporation of poplar powder greatly reduced brittleness, due to the good bonding capability and compatibility of cement covering powders well. Overall, this study presents a feasible way of using waste poplar powders to reduce the consumption of MgO and prepare environmental-friendly composites.