Study of using micro‐nano bubble to improve workability and durability of self‐compact concrete

Developing self‐compacting concrete (SCC) with higher workability and durability properties by replacing mixing water with nano‐bubble without a decrease in mechanical strength is the purpose of this study. For this aim, different SCC mixtures were designed by using tap water and micro‐nano bubble and replacing silica fume, fly ash, slag, zeolite, and the mixture of fly ash and silica fume with cement. The workability, mechanical, and durability properties of the SCC mixture were tested according to ASTM and BS standards. In addition to air content test, for evaluation of the workability of SCCs, Slump flow in 10 and 60 min (for filling ability), V‐funnel, L Box, and J‐ring (for passing ability) were tested. For mechanical properties (compressive and tensile strength) and for durability of concretes (water penetration test and electrical resistivity) were tested. The workability test results indicate that using a micro‐nano bubble instead of tap water in different SCC mixture designs did not make a significant difference. But in hardened concretes, using the micro‐nano bubble increase the compressive and tensile strength of different concrete mixture designs except for SCC including fly ash and silica fume. Depth of water penetration and 30 min water adsorption for different concrete mix designs decreased compared to using tap water except for the sample contain zeolite, which increased slightly. Also, the permeability of concrete was tested by electrical resistivity. The results indicate that using the micro‐nano bubble decrease electrical resistivity and they were in the very low range (37–254 Ω‐m). The scanning electron microscope image confirmed in increasing mechanical and durability properties for a sample where used the micro‐nano bubble without pozzolans.