The physical and chemical impact of manufactured sand as a partial replacement material in Ultra-High Performance Concrete (UHPC)

In this paper, a type of typical locally available manufactured sand (MS) was utilized, and its effect on the properties of Ultra-High Performance Concrete (UHPC) were studied, based on physical and chemical points of views. According to the modified Andreasen and Andresen [1] (MAA) model, the natural river sand (RS) were partially replaced by manufactured sand to design UHPC. Then, the properties of the developed UHPC were evaluated. The obtained experimental results shown that the addition of angular MS can disturb the particle packing skeleton of UHPC. Moreover, the flowability and volume stability of the developed UHPC can also be negatively affected by the inclusion of MS. Especially the UHPC autogenous shrinkage, which could be even increased by 39.2%, when 50% of RS was replaced by MS. Additionally, based on the chemical reaction and microstructure development points of view, the use of MS at replacement levels up to 50% has limited influence on the hydration process and pore size distribution of UHPC, while the micro-hardness and SEM measurements showed that the connection of cementitious matrix with MS was more compact than that with RS, which should be attributed to the typical surface characteristics of the utilized MS particles.