Mechanical properties and durability of concrete containing coal mine waste rock, F-class fly ash, and nano-silica for sustainable development

Abstract

Natural resources such as river sand and rock used for producing concrete tend to be depleted. Thus, it is necessary to find a new material for substituting the natural aggregate in concrete production. Waste materials such as coal mine waste rock, if these wastes are not treated properly, they negatively affect the environment and human health. Therefore, utilizing waste rock from coal mining to partially substitute aggregate in concrete manufacturing for sustainable development is urgent. In this study, crushed sand from coal mine waste rock (CSM) has partially replaced river sand and combined with F-class fly ash (FFA) and nano-silica (NS) to produce concrete with a minimum compressive strength of 35 MPa. Specifically, 40% of cement was replaced by 38% of FFA and 2% of NS, and river sand (RS) was replaced by CSM at contents of 0%, 10%, 20%, 30%, 40%, and 50%. Mechanical properties, durability, and environmental impact were conducted to evaluate the application of CSM in concrete for sustainable development. The results showed that the synergistic effects of fly ash and nano-silica in concrete helped CSM more environmentally friendly. The mechanical properties and durability of concrete using CSM were close to those of normal concrete using conventional aggregates with the required compressive strength of 35 MPa. The use of mine waste in concrete production has shown its effectiveness in replacing traditional aggregates (river sand), which can minimize environmental impact for sustainable development.