Research on the Mechanical Properties of Modified Sticky Rice–Lime Mortar by Graphene Oxide/Nanosilica Hybrid

ABSTRACT Sticky rice–lime mortar (SRLM) has important effects in the field of ancient building restoration. Its compressive and bond strengths need further improvements to allow it to contribute more to the repair of ancient structures. The graphene oxide/nanosilica (GO/NS) hybrid was synthesized via a sol-gel technique in this research, and its successful preparation was confirmed through four techniques: scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy, and Fourier transform infrared spectroscopy. Different contents of the GO/NS hybrid were incorporated into the SRLM for modification studies. Compressive and tensile bond experiments were performed on the SRLM. Microscopic analysis, including SEM and XRD, were employed to reveal the modification mechanism of the GO/NS hybrid. The findings demonstrated that as the GO/NS content increased, the modified mortar’s mechanical properties exhibited a gradual enhancement followed by a decline as additive content rose. When the concentration of GO/NS hybrid reached 0.06 %, the modified mortar exhibited the most significant improvement in both the compressive and bonding strengths. The addition of 0.06 % GO/NS increased the 7 d and 28 d compressive strengths of the mortar by 140.00 % and 88.69 %, respectively, whereas the tensile bond strength at 28 days increased by 1,202.86 %. The microscopic test findings revealed that the GO/NS hybrid, on the one hand, maintained the original two-dimensional fold structure of GO, reduced the agglomeration phenomenon, and allowed it to effectively serve with bridging effects in the mortar. On the other hand, it facilitated the carbonation reaction of the mortar, significantly improved its internal structure, and thus enhanced the compressive and bond strength of the SRLM.