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Title:	Behavior of residual soil with bentonite and nanocarbons
Authors:	Jamal Mansuor Abdulsalam Alsharef (P75403)
Supervisor:	Mohd Raihan Taha, Prof. Dr.
Keywords:	Soil mechanics Carbon nanotubes Bentonite Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	20-Dec-2018
Description:	The improvement of soil using nanocarbons (NC) is the main subject of this study. Two types of NC, i.e. carbon nanotube (CNT) and carbon nanofiber (CNF) are used. These are some of the toughest and stiffest materials ever produced and now are available in the market for use as potential soil improvement material. Furthermore, these additives are powerless against the attack of aggressive chemicals of soil stabilization using chemical additives. This situation demands the introduction of new construction materials other which are effective and at the same time environmental friendly. This study addressed an improvement to the dispersion of NCs in soil by using sonication and investigate the effect of two different types of NCs reinforcement on the physical properties of soils. Moreover, study the interface behavior between soil particles and nanocarbon, and the effect of NCs on the mechanical behavior of soil were also studied. The main soil used for testing is a local metasedimentary residual soil. Due to high aspect ratio and strong van der Waal forces between the filaments of CNT and CNF, they readily agglomerate and form bundles when mixed with water. Sonication method was used to mix NC filaments with soil. A quantity of 0.05%, 0.075%, 0.10% and 0.20 % of NC by weight of dry soil were mixed with the residual soil and different ratios of bentonite (0 %, 10 % and 20 %). The bentonite was used to replicate a soil with cracking problems. Various tests were performed to determine the influence of the NC on plasticity index, shrinkage, volume change, compressive strength, tensile strength, desiccation cracks (CIF), and hydraulic conductivity of compacted soil samples. The sonicated specimens showed that soil and NC was prevented to re-agglomerate, thus stabilizing their dispersion. It was found that a small amount of NC decreased the optimum moisture content, increased maximum dry density, and reduced the plasticity index. The results also showed that unconfined compressive strength and indirect tensile strength clearly increased with increasing NC contents. An improvement of up to 238% in the compressive and 247% in the tensile strength were observed compared to specimens without NC. Furthermore, the NC increased the peak and residual strength of the soil. CNF showed more improvement possibly because their aspect ratio is greater than CNT. The CIF of soil decreased measurably from 2% to 0.1% with the addition of 0.2% CNF. In addition, the hydraulic conductivity decreased to 1.44 x 10-09 m/s and 7.44 x 10-10 m/s for CNT and CNF, respectively, from soil without NC (2.16 x 10-09 m/s). The mineralogy and microstructure were analyzed by using a scanning electron microscope. It was observed that NC acted as bridges across cracks and voids, possibly aiding load-transfer and filling-in pore spaces in the samples. This subsequently led to an increase in strength, reduce cracking and lowering the hydraulic conductivity. Thus, in general, based on the results of this study, it can be concluded that NC has a big potential as a soil improvement material.,Ph.D.
Pages:	234
Call Number:	TA710.S373 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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