Investigating the effect of slag, magnesium nano oxide and copper nano oxide on the properties of high strength concrete under different curing conditions with the help of electrical resistivity monitoring method

 During the service period, concrete may come into contact with harsh environmental conditions, ultra-high performance concrete can be considered as a suitable option due to its unique strength and durability. In this study, for the first time, the effect of nanoparticles of magnesium oxide and copper oxide with amounts of 0.5, 1 and 2% separately and combined with different amounts of iron slag (2.5, 5 and 10%) on the compressive strength and electrical resistance of UHPC contains a constant content of PVA fibers in two operating modes Standard and accelerated curing (immersion in water at 95°C) were studied for different ages. Moreover, the Scanning Electron Microscopy test (SEM) is conducted on the specimens to understand the concrete's microstructure better. The results show that by using the heat treatment method and microstructure modification in the presence of new nano materials, it is possible to create a higher potential than UHPC in terms of compressive strength and electrical resistivity. So that after 90 days, the compressive strength for each of the specimens containing 1% of magnesium oxide and copper oxide nanomaterials respectively increased the compressive strength by approximately 37.4% and 37.1% compared to the 7-day sample. While the growth of the compressive strength in the accelerated mode for the mentioned specimens was 16.8% and 18.8%, respectively, compared to the standard curing. In addition, by obtaining accurate experimental relationships between the two parameters of compressive strength and electrical resistivity a non-destructive method for predicting compressive strength has been presented.