High-performance Reactive Magnesium Cement Incorporating Hollow Natural Fiber and Silica Sand

Abstract

Global warming caused by CO2 emissions makes reactive magnesium cement (RMC) increasingly attractive due to its ability to sequester CO2, however, the diffusion of CO2 in RMC is severely limited by the dense hydrated magnesium carbonates (HMCs) formed on the outer layer. This work utilizes hollow natural fiber (e.g., sisal fiber) to facilitate the diffusion of CO2 into the deep part of the RMC specimen. Combining with adding silica sand as a filling agent, the mechanical strength can be enhanced from 42.4 MPa of the control group to 92.6 MPa of the specimen with 2 vol.% sisal fiber, this is attributed to that the addition of sisal fiber significantly enhances the carbonation depth. FTIR and XPS results further prove that the addition of 2 vol.% or more sisal fiber can improve the carbonation degree by over 200%, leading to a sharp reduction of CO2 emission from 37 kg/(m3>MPa) of the control group to 12.1 kg/(m3∘MPa) of the specimen with 2 vol.% sisal fiber. Therefore, adding hollow natural fiber and silica sand to RMC can be a promising approach to make RMC stronger and more sustainable.