Innovative self-sensing fiber-reinforced cemented sand with hybrid CNT/GNP

Abstract

This study is a systematic attempt to develop a self-sensing fiber-reinforced cemented sand (CS) with high physical, mechanical, durability, and piezoresistivity performances. In this route, different concentrations of Dyneema, glass, and polypropylene (PP) fibers were incorporated into CS containing 0.17% hybrid carbon nanotubes and graphene nanoplatelets. The specimens were fabricated using the standard Proctor compaction method and tested at the optimum water content. The mechanical, microstructural, and durability performances of the specimens were evaluated through various types of tests. Further, the piezoresistivity of the specimens was evaluated under compression cyclic loads using the four probes method. The incorporation of 1.0% glass and Dyneema fiber as the optimum percent increased the unconfined compression strength (UCS) (29% and 82%, respectively) and the maximum dry density of the CS; however, reinforcing of the specimens with PP fiber at a concentration in the range of 0.5%-1.5% generally reduced the UCS of the specimens. The pullout test results exhibited a considerable interfacial performance for the Dyneema fiber. The CS reinforced with 1.0% Dyneema and glass fiber demonstrated a lower weight loss after 12 wetting and drying cycles compared to other specimens. The maximum gauge factors were also achieved for Dyneema fiber-reinforced CS. The outcomes of this study, balanced with sustainable issues, contribute to the development of the new era of smart structures, with applications to roller-compacted-concrete dams, rammed earth, and particularly in structural layers in transportation infrastructure.

Effects of Electrodes Layout and Filler Scale on Percolation Threshold and Piezoresistivity Performances of a Cementitious-Based Geocomposite

“…In the compression loading mode, the results showed a proper correlation between the variation in FCR and strain. Negative values were measured for the FCR because of a decrease in the electrical resistance during compression loading relative to the initial electrical resistance of the composite [ 40 ]. In fact, the paths formed by conductive fillers got closer together during compression loading, which resulted in the decreased electrical resistivity and consequently enhanced the electrical conductivity of the composite.…”

“…Since, in sand stabilisation, the cement content usually varies by approximately 10% owing to the target strength of the sand–cement [ 38 , 39 ], in this study, 10% cement (by the weight of the dry sand) was also utilized for SCG preparation. Based on the literature [ 3 , 21 , 40 ], the optimum water content for the CNM-reinforced stabilised sand with similar cement content and sand grading was around 7%. Hence, the amount of water content for all the specimens was considered to be 7% (by the weight of the dry sand) and they were fabricated by the compaction methods.…”

A review of intrinsic self-sensing cementitious composites and prospects for their application in transport infrastructures

“…However, the complexity of graphene production and the relatively high cost of this conductive filler limit its use. The high specific surface area of dispersed graphene facilitates the absorption of water during composite fabrication which thickens the consistency of the cementitious composite or even halts the hydration process of the cement, especially in cases with low water content [67,127,128]. Hence, it is advisable to combine graphene with other effective carbon conductive fillers to decrease its concentration and production costs without reducing the sensitivity of the composite or sacrificing the desirable properties of graphene [129].…”

Three-dimensional braided composites as innovative smart structural reinforcements

“…These monitoring techniques create local low-resolution detection systems for concrete structures [12][13][14]. Furthermore, these sensors have serious drawbacks, such as low durability, poor sensitivity, high cost of production, high time consumption, installation costs, and difficulties in assuring proper bond conditions with cementitious composite [15][16][17][18]. Among SHM techniques, carbon-reinforced braided composite rods (CBCRs) have provided a more reliable, real-time, and practical solution for concrete structure damage monitoring based on the piezoresistivity principle [1,19,20].…”