Influence of Wheat Straw Ash as Partial Substitute of Cement on Properties of High-Strength Concrete Incorporating Graphene Oxide

The worldwide move to the utilization of sustainable/green materials has motivated the drive for the use of different supplemental materials in the field of structural application. Further, the utilization of nano-materials has also been amplified for improving concrete properties. The present study mainly emphasizes the strengthening influence of graphene oxide on high-strength concrete cast in the presence and absence of wheat straw ash. Portland cement was substituted with 15% wheat straw ash (WSA) by cement weight. Graphene oxide was included in various doses of 0.020%, 0.040%, 0.060%, and 0.080% by cement weight. Properties of nano-engineered samples were assessed in terms of mechanics (compressive, split tensile, and flexural strength), durability (acid resistance, rapid chloride ions, water absorption, and sorptivity), and $x$-ray diffraction (XRD) test. The test outcome showed that the mechanical and durability performance of high-strength concrete improved considerably on the inclusion of graphene oxide and was further enhanced through the fractional substitution of cement with 15% wheat straw ash. The optimal behavior in terms of durability and mechanical performance was obtained by a combination of 15% wheat straw ash and 0.060% graphene oxide, which improved compressive strength to 57.3 MPa and split tensile and flexural strength by 33% and 49%, and reduced water absorption, sorptivity, and resistance against acid to 14%, 21%, and 5.6%. Incrementing the dose of graphene oxide to more than 0.060% led to a decline in mechanical strength and durability behavior. Moreover, the XRD showed that samples comprising both wheat straw ash and graphene oxide displayed dense concrete by consuming $\mathrm{Ca}{(\mathrm{OH})}_2$ and forming an extra gel of calcium silicate hydrate in the matrix, which concludes the application of utilizing graphene oxide and wheat straw ash in high-strength concrete.