“There's Plenty of Room at the Bottom" was a lecture given by physicist Richard Feynman at an American Physical Society meeting at Caltech on December 29 1959, in which he introduced Nanotechnology first time ever.Since then, Nanotechnological achievements is providing a modern approach in all Sciences.
Several applications have been developed for this specific sector to improve the durability and enhanced performance of construction components, energy efficiency and safety of the buildings, facilitating the ease of maintenance and to provide increased living comfort.
Nanotechnology can be proposed in geotechnical engineering as two issues :-
Understanding materials’ nature and their structures have been always of much significance. Microscopic structure of fine soils can be used as an index to identify the type of environmental processes and estimating its resistance. Nanosols with size range of 1-100 nm are the smallest particles in soil which are in the form of nanoplane, nanowire, nanotube, or nanoparticles. Transverse electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) are direct methods for particulate imaging at nanoscale through which some information such as dimension, shape, and morphology of particles can be yielded. SEM provides a greater image of a specimen using electrons. In this technique, a beam of electrons is focused vertically on the specimen. By interaction of the beam with the specimen in a vacuum, electrons and X-ray are emitted from the specimen. Then, detectors collect X-ray, primary electrons, and those electrons caused by the interaction of primary electrons with the specimen; these are subsequently converted into signal and transferred to the screen, so the final image is prepared. TEM uses electron emission towards the specimen, similar to SEM; however, in TEM the emitted electrons pass through the specimen and reach a phosphorous detector so as to provide a pattern of specimen’s structure. This device has also been employed for imaging soil’s nanostructure. In AFM, a sharp tip connected to a cantilever scans the specimen’s surface. In geotechnics, AFM images are frequently used to study the surface morphology of soil nanoparticles, measure the adhesive force between soil particles, and measure friction angle between particulate soil particle.
Numerous studies have been conducted regarding the use of nanoparticles for improvement of soil strength parameters. The nanomaterials which have been more frequently used for changing the geotechnical properties is silica nanoparticles which influence the consolidation, permeability, indices, and strength properties of soil. The silica nanoparticles enhance soil’s strength against consolidation and permeability and also increase sand compressive strength. Silica nanoparticles also increase soil’s cohesion/adhesiveness and decrease its viscosity. As a result, cohesion/adhesiveness depends on the percentage of nanoparticles. To study the effect of silica nanoparticles in dimension range of 5-100 nm, oedometer test, triaxial test, and compressive test are carried out which show that soil strength increases with time, such that the soil containing nanoparticles is ductile in initial stages and subsequently becomes elastoplastic.
Nanoparticles influence soil in their specific properties. Generally, when materials get smaller to nanoscale, their properties become remarkably different or have an increase. The following list provides an overview of such changes:
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