Utilization of waste marble powder in cement-based materials by incorporating nano silica

摘要

In order to promote the utilization of waste marble powder (WMP) in cement-based materials, an attempt to improve the mechanical properties of cement-WMP system by incorporating nano silica (NS) was made in this study. 16 mortar mixes incorporating NS (0%, 1%, 2% and 3%) and WMP (0%, 10%, 20% and 30%) as partial replacement of Portland cement were designed. Mechanical properties, standard water requirement, setting time and the fluidity were investigated, and the hydration and microstructure characteristics were also analyzed with hydration heat, X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and scanning electron microscope (SEM). Results demonstrated that replacement of cement by WMP obviously reduced the compressive strength, despite that calcite in WMP partly reacted with aluminum phase to produce the carbonate AFm phase instead of monosulphate. Furthermore, NS showed positive effect on strength development of cement-WMP system, and the reason was due to the nucleation effect, filler effect and its ultra-high pozzolanic reactivity. NS could partially offset the adverse effect on the compressive strength of mortar caused by WMP, and 10% WMP and 3% NS showed an optimum proportion. Such findings were expected to expedite the use of WMP in cement-based materials. (C) 2019 Elsevier Ltd. All rights reserved.