Abstract
The remarkable mechanical properties and piezo-responses of carbon nanotubes (CNT) makes this group of nanomaterials an ideal candidate for use in smart cementitious materials to monitor forces and the corresponding structural health conditions of civil structures. However, the inconsistency in measurements is the major challenge of CNT-enabled smart cementitious materials to be widely applied for force detection. In this study, the modified tapioca starch co-polymer is introduced to surface treat the CNTs for a better dispersion of CNTs; thus, to reduce the inconsistency of force measurements of the CNTs modified smart cementitious materials. Cement mortar with bare (unmodified) CNTs (direct mixing method) and surfactant surface treated CNTs using sodium dodecyl benzenesulfonate (NaDDBS) were used as the control. The experimental results showed that when compared with samples made from bare CNTs, the samples made by modified tapioca starch co-polymer coated CNTs (CCNTs) showed higher dynamic load induced piezo-responses with significantly improved consistency and less hysteresis in the cementitious materials. When compared with the samples prepared with the surfactant method, the samples made by the developed CCNTs showed slightly increased force detection sensitivity with significantly improved consistency in piezo-response and only minor hysteresis, indicating enhanced dispersion effectiveness. The new CNT surface coating method can be scaled up easily to cater the potential industry needs for future wide application of smart cementitious materials.
Highlights
Cementitious materials are one of the largest commodity groups consumed worldwide and are widely used in various civil engineering infrastructures
Searching for a more consistent force measurement resulted from a well dispersed carbon nanotubes (CNT) by surface treatment using an environmentally friend polymer, this study investigates the effectiveness of using octenyl succinic anhydride (OSA) modified tapioca starch-based copolymer to disperse CNTs in water and in smart cement mortar
To study the force sensitivity of CNTs enabled smart cement mortar resulted from three different dispersion methods, including the direct mixing method using bare CNTs (Group DM), currently commercially available dispersion method using surfactant surface treatment (Group surface treatment method (SM)) and the proposed surface treatment using modified tapioca starch (Group coated CNTs (CCNTs)), three groups of samples were made for each dispersion methods
Summary
Cementitious materials are one of the largest commodity groups consumed worldwide and are widely used in various civil engineering infrastructures. The physical adsorption of these copolymers onto CNTs surfaces increases the hydrophobic feature of the OSA, which may effectively prevent the aggregation of CNTs. the electrostatic/steric repulsive forces of the copolymer may overcome some Van der Waals force between CNTs. there was no such study reported yet in the literature for investigating the use of OSA modified tapioca starch as dispersant for CNTs in smart cementitious materials. Searching for a more consistent force measurement resulted from a well dispersed CNTs by surface treatment using an environmentally friend polymer, this study investigates the effectiveness of using OSA modified tapioca starch-based copolymer to disperse CNTs in water and in smart cement mortar. The organization of the remainder of this paper is as follows—Section 2 introduces the used material and methodology for the experimental investigation on the sensing effectiveness of different CNTs dispersion methods; Section 3 describes the experimental design, the method of data collection and signal processing; Section 4 presents the experimental results and compares the experimental results from different CNTs dispersion methods and discusses the effect of CNTs percentages on force sensitivity; Section 5 concludes the work and suggests future work
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