Improving the mechanical properties of recycled aggregate concrete with graphene

This article presents the results of a preliminary research to explore the
feasibility of using graphene to improve mechanical properties of recycled
aggregate concrete (RAC). Graphene of different nominal flake sizes (5, 10
and 20 lm) and concentrations of 0.01%, 0.02%, 0.05% and 0.1% of the
combined weight of cement and sand were incorporated into RAC with
and without crumb rubber. The results indicate that there was no improvement
in mechanical properties of recycled aggregates (RAs) concrete with
crumb rubber. Also, if aggregates were not washed, even without any
crumb rubber, adding graphene was not effective in improving mechanical
properties of RAC due to excessive dust of unwashed RAs. However, the
results reveal that by agitating RAs in water to remove excessive dust, adding
small amount of graphene improves the mechanical properties of RAC.
By adding 0.01% graphene flakes, the average compressive and splitting
tensile strengths of RAC were increased from those of RAC without graphene
by 43.9% and 24.1% to 39.14 and 3.76MPa, respectively, which are
comparable to those of concrete using natural aggregates (NAs). However,
using more graphene flakes did not result in any further improvement.