Influence of Carbon Nanofibers on the Shear Strength and Comparing Cohesion of Direct Shear Test and AFM

Abstract

The stabilization and enhancement of the engineering properties of fine and coarse grained soil has heavily relied on reinforcement and admixture materials. This study discusses the effect of the additive of Carbon nanofibers (CNF) on the characteristics of soils in terms of shear strength. The content of CNF was changed within the range of 0.05 to 0.2% by total dry weight of the reinforced samples. In achieving the objective of minimizing the number of experimental runs and thus conserve material, time as well as overall cost, the Box–Behnken approach was chosen as the method for statistical prediction. The scanning electron microscopy (SEM) and Atomic force microscopy (AFM) has been utilized in studying features of CNF in stabilized soil samples and force at the origin of the cohesion (c) of soil. Test results reveal that the increases peak and residual shear strength of the reinforcement soil samples were increased with an increase in the CNF content. The pre-eminence of ionic correlation forces in the cohesion of soil was confirmed by the force (cohesion) measurements by (AFM). The statistical prediction’s relatively high correlation coefficients justified the results.

Ultrasonic Dispersion of Nanocarbons in Soil-water Mixture

“…The potential for the NCs to intimately interact with the clay phases and affect the microstructure of the soil mixture after the sonication action, can be used to effectively stabilize and restrain the dispersion of CNFs in soil composite. With using this method to mixed soil with NCs it can be even improve the physical and mechanical properties of soil [25][26][27][28][29]. This finding also agrees with the hypotheses of Yazdanbakhsh and Grasley [18], Sanchez and Ince [30] who used silica fume particles (< 1 µm) to act as wedges between the CNFs thus physically keeping the particles far enough apart to render inter-fiber attractive forces ineffective.…”

Effects of Nano-Carbon Reinforcement on the Swelling and Shrinkage Behaviour of Soil

“…The effectiveness of NCs depends on two primary features; the distribution of NCs within the material and the bonding strength i.e. energy between NCs surface and the material (Alsharef et al 2017a;Nochaiya & Chaipanich 2011). NCs are strongly drawn to each other due to their high van der Waals forces, Moreover, CNTs are more influenced by van der Waals forces than CNFs since their surface-tovolume ratio is higher.…”

Evaluation of the Dispersion Stability of Nanocarbons Using Zeta Potential in Distilled Water

“…The prediction was considerably satisfactory since the shear test process's F-value was recorded at 11.23. In the evaluation of the zeta potential function's prediction range in comparison to its related error, the tolerable precision term was recorded to be 10.593 more than 4, which is the value routinely desired to confirm the statistical prediction fitness [21,24]. Similarly, for CNF Table 3 shows the ANOVA results of zeta potential when adding CNF.…”

“…A sample of NCs was mixed with distilled water, an ultrasonic tip was placed in the beaker, and the mixture was sonicated to disagglomerate the NCs while avoiding possible nanofibers fragmentation [21,22]. All samples were saved in a plastic beaker and majoure the zita potential after 30 days Figure 1.…”