Abstract
The interface of aggregate and cementitious phase largely determines the mechanical properties and durability performances of cement mortar and concrete. This work demonstrates a low-cost, facile, and targeted approach to improve interfacial transition zone (ITZ), using sand particles pre-saturated in a graphene oxide (GO) dispersion (i.e., GO@Sand hybrid). The use of GO@Sand increased the 28-day compressive and flexural strengths of cement mortar specimens (w/c ratio of 0.38) by 38% and 44%, respectively, relative to their counterparts fabricated by random mixing. The improvements in strengths can be mainly attributed to the enhancement in the ITZ. Specifically, a higher percentage of hydration products (from 43.34% to 80.00%) was generated and a higher Ca/Si ratio was detected in the ITZ region by employing the GO@Sand hybrid, and the microstructure tended to feature lower porosity (decreased from 43.5% to 30.1%). The findings of this study highlight the promising effectiveness of ITZ nano-engineering by the adsorbed GO nanosheets.