Unconfined Compression Research Papers - Academia.edu (original) (raw)

A poly(vinyl alcohol) (PVA) hydrogel composite scaffold containing N,O-carboxymethylated chitosan (NOCC) was tested to assess its potential as a scaffold for cartilage tissue engineering in a weight-bearing environment. The mechanical properties under unconfined compression for different hydration periods were investigated. The effect of supplementing PVA with NOCC (20 wt.% PVA:5 vol.% NOCC) produced a porosity of 43.3%, and this was compared against a non-porous PVA hydrogel (20 g PVA: 100 ml of water, control). Under non-hydrated conditions, the porous PVA-NOCC hydrogel behaved in a similar way to the control non-porous PVA hydrogel, with similar non-linear stress-strain response under unconfined compression (0-30% strain). After 7 days' hydration, the porous hydrogel demonstrated a reduced stiffness (0.002 kPa, at 25%) strain), resulting in a more linear stiffness relationship over a range of 0-30% strain. Poisson's ratio for the hydrated non-porous and porous hydrogels ranged between 0.73 and 1.18, and 0.76 and 1.33, respectively, suggesting a greater fluid flow when loaded. The stress relaxation function for the porous hydrogel was affected by the hydration period (from 0 to 600 s); however the percentage stress relaxation regained by about 95%, after 1200 s for all hydration periods assessed. No significant differences were found between the different hydration periods between the porous hydrogels and control. The calculated aggregate modulus, H(A), for the porous hydrogel reduced drastically from 10.99 kPa in its non-hydrated state to about 0.001 kPa after 7 days' hydration, with the calculated shear modulus reducing from 30.92 to 0.14 kPa, respectively. The porous PVA-NOCC hydrogel conformed to a biphasic, viscoelastic model, which has the desired properties required for any scaffold in cartilage tissue engineering. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Stabilization of soil is important to enhance the engineering properties of expansive soil like strength, volume stability and durability. The Black cotton soils are very hard when dry, but lose its strength completely when in wet condition Expansive soils (black cotton soil) are a worldwide problem that poses several challenges for civil Engineers. In this research has been made to stabilize the soil using Fly ash and Lime. Experimental work has been carried out with 10%, 20%, and 30% of Fly ash as well 5 %, 10 % and 15% of lime content. The experimental work is based on different percentages of Fly ash and lime content in soil on tests for soil Atterberg limit, California Bearing Ratio test, Unconfined Compression Test and Standard Proctor Test. The aim of this project was done by utilizing binding materials to improve the engineering properties of the black cotton soil.

— The rapid expansion in the civil and industrial activities in the eastern area of Saudi Arabia has made the improvement of local soils an indispensable task. It is essential for the designers and builders to be able to select an appropriate stabilizer to fulfill the engineering, environmental and economic requirements of the local soils. This study is to evaluate the economic utilization as well as the possibility of improving the mechanical properties of local soils utilizing indigenous industrial by-products, such as oil fuel ash (OFA), cement kiln dust (CKD) and electric arc furnace dust (EAFD). Three types of eastern Saudi soils, namely sand, non-plastic marl and sabkha, were treated with different dosages of the selected industrial by-products. The mechanical properties of the stabilized soils were evaluated by determining the unconfined compressive strength and the durability of the developed mixtures. Micro-characterization methods, such as x-ray diffraction (XRD) and scanning electron microscopy (SEM), were utilized to qualitatively study the mechanisms of soil stabilization due to the use of the selected industrial by-products. Results of this investigation indicated that non-plastic marl stabilized with 7% cement was found to be suitable for base course in rigid pavements while the same soil stabilized with 5% cement or with 30% EAFD plus 2% cement or with 30% CKD plus 2% cement was found to be suitable for sub-base course. Non-plastic marl stabilized with 20% EAFD plus 2% cement was found to be suitable as a sub-base in rigid pavements. Dune sand stabilized with 7% cement or with 30% CKD plus 2% cement or with 20% EAFD plus 2% cement was found to be suitable for sub-base course in rigid pavements. Sand stabilized with 30% EAFD was found to be an appropriate material for sub-base in flexible pavements. However, sabkha stabilized with 7% cement or with 30% CKD plus 2% cement was found to be suitable for sub-base course in rigid pavements.

- by IJAERS Journal
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- Disinfection by-products, CBR, XRD, Stabilization and Reconstruction

Soil Cement with admixture can be used together to get the more stabilized subgrade on roads. When the soil is mixed with cement and then with admixture the properties of the soil get changed. The aim of the study is to review on stabilization of subgrade using soil cement with admixtures. In the experiment the soil sample has been taken from the Vadodara region, the soil is found granular soil with sufficient fines and many laboratory tests has been conducted on that soil sample and soil cement with admixtures with varying percentage of cement and admixture. The experiments which have performed are Standard Proctor Test, California Bearing Ratio Test (CBR) & Unconfined Compression Test (UCT) by adding 5 %, 10%, 15%, 20% of the cement content by volume of dry soil and the Admixture which has used is Lime of 5% by weight of the dry soil. Lime is chosen because lime alters the nature of the adsorbed layer and gives pozzolanic action.