•Ultra high performance concrete (UHPC) for multipurpose.•Porosity decrease with increasing nano-silica (nS) content.•Strength increased with addition of 2% nS in UHPC with up to 50% barite sand.•Resistance to radiation was improved with the addition of barite aggregate. The development of building materials with improved characteristics and their application for increasing structure durability and sustainability is one of the goals in construction sector. The main objective of this paper is to evaluate the influence of nano-silica replacement of cement (2% or 5%) and aggregate type (quartz, barite or its combination 50:50 by volume) on the properties of ultra high performance concrete (UHPC). UHPC with nano-silica and combination of barite and quartz aggregate is composite which has finer pore-size distribution, improvement in compressive and flexural strength and in radiation protection characteristics, with potential usage as building material for hospitals and nuclear facilities.