Comparison of effectiveness of blending and impregnation applications of dispersed nanoparticles on performance of cementitious composites

Abstract

Blended or impregnated forms of nanomaterials in cementitious composites play a key role in determining mortar performance. In this study, the performance of graphene oxide (GO), silver nanoparticles (AgNPs), pristine multi-wall carbon nanotubes (MWCNTs), and functionalized MWCNTs impregnated and blended cementitious composites were compared using principal component analysis (PCA). The highest recorded compressive strength at 28 days was 39.1 MPa corresponding to the impregnation of carboxylated MWCNTs, representing a 29% improvement compared to reference cementitious composites while blending of pristine MWCNTs achieved a maximum compressive strength of 50.37 MPa, representing a 45% improvement over the reference. The group of GO, low-density AgNPs, and hydroxylated MWCNT-impregnated cementitious composites achieved the best sulfuric acid resistance, with an average compressive strength of 30.15 MPa, water absorption of 21.82%, porosity of 36.29%, and ultrasonic pulse velocity of 2.91 km/s due to preventing harmful sulfate ions entering their structure. After sulfuric acid exposure, a 5% compressive strength decrease occurred due to the presence of the functional groups of GO, hydroxylated MWCNTs, and small, low-density AgNPs on the surface of the cementitious composites. These results show that the impregnation method effectively improves cementitious composites' durability. Using PCA analysis, the pristine MWCNTs-blended cementitious composites were determined as the optimum specimen to obtain a durable mortar both pre- and post-acid exposure.