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Title:	Effect of nanomaterials on the shrinkage and expansive behaviour of soil
Authors:	Omer Muhie Eldeen Taha (P54859)
Supervisor:	Mohd Raihan Taha, Prof. Dr.
Keywords:	Nanostructured materials Soils Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	13-Mar-2014
Description:	This study presents an experimental investigation on the shrinkage and expansive behaviour of the soils before and after drying. This behaviour is of great importance in geotechnical and geoenvironmental engineering. It is the cause of desiccation cracks which leads to damage in soil structures. Tests were performed on four types of soils mixed with three nanomaterials of different percentages. The dry soil is mixed with nanomaterials into two stages. Initially premix or hand mixed, the quantity of soil was divided into ten portions and each portion was spread in a square pan then the required amount of nanomaterial was added using sieve number 200. Each portion was mixed manually for 5 minutes then placed in a bowl and subsequently the mixture was mixed by a horizontal cylindrical mixer machine at 139 rpm for three hours. In order to avoid the segregation problem, the soil-nanomaterial mixture was mixed with the required water content directly then the entire mixture was placed in a sealed plastic bags and left for 24 hours for hydration. The soil specimens were compacted under the condition of maximum dry unit weight and optimum water content using standard compaction test. The untreated soil values were used as control points for comparison purposes. The shrinkage and expansion tests were conducted to investigate the effect of three different nanomaterials (nano-clay, nano-alumina, and nano-copper) on repressing strains in compacted residual soil mixed with different ratios of bentonite (S1 = 0 % bentonite, S2 = 5 % bentonite, S3 = 10 % bentonite, and S4 = 20 % bentonite). In addition, the influence of nanomaterials on suction and hydraulic conductivity of compacted soil-bentonite mixture with different plasticity index was evaluated. It was found that with the addition of optimum percentage of nano-material, both the swelling and shrinkage strains reduced. The results also show that nanomaterials decrease the development of desiccation cracks on the surface of compacted samples without increasing the hydraulic conductivity. The soil suction and hydraulic conductivity of the compacted soil-bentonite mixtures was measured before and after the addition of nanomaterials. Soil water characteristic curves (SWCC) were developed for compacted soil samples (with and without nanomaterial) using a pressure membrane apparatus. The relative location of SWCC plots were lower for the soil samples mixed with nanomaterials. The soil hydraulic conductivity decreased significantly with increasing nanomaterial content. The decrease in hydraulic conductivity was possibly caused by reduction of the effective porosity due to pore clogging. The results from tested samples after 1 to 4 drying cycles show that the largest rise in soil hydraulic conductivity occurred at first or second drying. Adding nanomaterial can also decrease the rising in soil hydraulic conductivity by as much as 7 times for high plasticity soil samples during drying cycles.,Ph.D.
Pages:	144
Call Number:	TA418.9.N35T334 2014 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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