Exploring the binding potential of magnesium oxysulfate cement with multi-source solid wastes

Abstract

The great increase of carbon emission and waste generation has been a major threat to sustainable constructions and buildings. To address this, magnesium oxysulfate cement (MOSC) has recently been introduced as a green and sustainable alternative of Portland cement with lower carbon footprints. This article investigated the binding capability of MOSC with multi-source industrial and forestry wastes by mechanical experiments. 18 samples with waste dosage of 0–70 wt% substituting MgO were prepared and cured for 90d. Multi-source solid wastes improved the flexural strength up to 57.05% and reduced the compressive strength by 3.44% at least. The maximum displacement and absorbed energy before fracture were increased by 63%∼226% and 79%∼274% under flexural loads; the energy absorption capacity under compressive loads reduced by 6.75%∼30%. Six indexes were defined to compare the effects based on both Index Ranking method and Targeted Index Value method. Four samples exhibiting outstanding mechanical strength and low brittleness were found by substituting 40%∼65% mass of MgO. The optimal sample consisting of 20 wt% poplar powder, 20 wt% fly ash, 20 wt% ground slag and 5 wt% bamboo powders as MgO’ mass had flexural and compressive strength of 17 MPa and 76 MPa, respectively. Mechanism of wastes’ effects on MOSC was discussed by microscopic experiments. The economic and environmental benefits as well as potential application of the optimal composite were discussed. These findings will contribute to the development of more sustainable cement products and improve the utilization of multi-source solid wastes.