Ultra-Sensitive Affordable Cementitious Composite with High Mechanical and Microstructural Performances by Hybrid CNT/GNP

Abstract

In this paper a hybrid combination of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) was used for developing cementitious self-sensing composite with high mechanical, microstructural and durability performances. The mixture of these two nanoparticles with different 1D and 2D geometrical shapes can reduce the percolation threshold to a certain amount which can avoid agglomeration formation and also reinforce the microstructure due to percolation and electron quantum tunneling amplification. In this route, different concentrations of CNT + GNP were dispersed by Pluronic F-127 and tributyl phosphate (TBP) with 3 h sonication at 40 °C and incorporated into the cementitious mortar. Mechanical, microstructural, and durability of the reinforced mortar were investigated by various tests in different hydration periods (7, 28, and 90 days). Additionally, the piezoresistivity behavior of specimens was also evaluated by the four-probe method under flexural and compression cyclic loading. Results demonstrated that hybrid CNT + GNP can significantly improve mechanical and microstructural properties of cementitious composite by filler function, bridging cracks, and increasing hydration rate mechanisms. CNT + GNP intruded specimens also showed higher resistance against climatic cycle tests. Generally, the trend of all results demonstrates an optimal concentration of CNT (0.25%) + GNP (0.25%). Furthermore, increasing CNT + GNP concentration leads to sharp changes in electrical resistivity of reinforced specimens under small variation of strain achieving high gauge factor in both flexural and compression loading modes.

Development of a Novel Multifunctional Cementitious-Based Geocomposite by the Contribution of CNT and GNP

“…The FCR amounts did not reach zero at the end of each loading cycle and a negligible amount of FCR remained after unloading, which is consistent with the strain remaining at the end of each loading cycle, and was increased by increasing load cycles. These remaining amounts were lower than those of previous studies [5] due to the compaction fabrication methods.…”

“…According to these results, the percolation threshold for this type of reinforced CSS could be around 0.24% due to the insignificant effect of CNM on reducing electrical resistivity in increments beyond 0.24%. By comparing the results with other studies that used similar types of sand, cement, dispersion method, and CNM, in order to investigate piezoresistivity and electrical conductivity of cementitious mortar (W/C = 0.5) [ 5 , 28 ], it can be observed that decreasing the cement concentration in CNM-reinforced cementitious composite led to the reduction in electrical resistivity. Comparing these results also showed that the use of a compaction fabrication method can reduce the electrical resistivity by up to 80%.…”

“…Among all monitoring methods, self-sensing composites with intrinsic stress, strain, and damage sensing capabilities based on piezoresistivity provide a more integrated, real-time, and practical solution for infrastructure damage detection, considering geomaterial properties and nature. Although several studies have evaluated self-sensing in various composites, such as concrete, cement paste, polymer, and asphalt [ 1 , 2 , 3 , 4 , 5 ], little research exists that assesses the impact of this method in geomaterials. Self-sensing composites arise from the dispersion of the conductive phase in the non-conductive composite [ 6 , 7 , 8 ].…”

“…Furthermore, reinforcing cementitious composites by highly dispersed CNMs with low concentration can improve their mechanical, microstructural, and durability performance [ 10 , 22 , 23 , 24 , 25 , 26 ]. Recently, studies have been conducted on the synergic effects of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) on the mechanical, microstructural, durability, and piezoresistivity performances of cementitious mortar using compatible, affordable, and effective dispersion techniques [ 5 , 27 , 28 ]. These studies reported that hybrid CNTs/GNPs can improve percolation and electron tunneling effects, which increase the conductive path and, consequently, reduce the percolation threshold significantly.…”

Hybrid Carbon Microfibers-Graphite Fillers for Piezoresistive Cementitious Composites

“…They may also yield better mechanical capacity [ 23 ], decreased costs, and reduced environmental and health impacts from the reduction of the required amount of filler. Literature reports studies on hybrid doping, including carbon black-graphene [ 24 ], carbon nanotubes-graphene nanoplatelets [ 25 ], carbon nanotubes-nano carbon black [ 26 ], carbon nanotubes-carbon fibers [ 27 ], carbon black-conductive rubber fibers [ 28 ], carbon black-polypropylene fibers [ 29 ], steel fibers-carbon nanotubes [ 30 ], carbon black-block co-polymer (SEBS) [ 31 ].…”