Abstract
The problems of soft clayey soils are taken in considerations by many Iraqi geologists and civil engineers, because about 35% of the Iraqi clay soils (especially southern Iraq) are weak. Thus, it is necessary to improve the properties of such soils for road construction by means of using of various stabilizers such as sawdust ash. The main goal of the present study is to stabilize soft clay models with sawdust ash (SDA) additive using different percentages (0, 2, 4, 6, 8 and 10% by dry weight of soil). The results revealed that the additive has adverse effects on the property of soil indices by increasing its liquid limit and plasticity index due to clay content. The mixture of sawdust ashes with soft clay soils improves most other physical and mechanical properties of the soil, as expressed by a general reduction in specific gravity and maximum dry density (MDD), as well as a reduction in the compression coefficients (Cc and Cr) with an increase in SDA content. While increasing the optimum moisture content (OMC) and the undrained shear strength (cu) with the increase in SDA content. The stabilized soils (with 4 and 10% ash content) resulted in low CBR values (1.6-1.2%) which can be used as sub-base. The SDA can be considered as a cheap and acceptable stabilizing agent in road construction for improving most of the geotechnical properties of the soft clayey soil.
Highlights
Soft clay soils are recent alluvial deposits presumably formed through the most recent 10,000 years described by their featureless and flat ground surface
Based on the specification of maximum liquid limit of 40% by the Federal Ministry of Works and Housing for soils to be used as sub-grade materials, since the average liquid limits of natural clayey soil samples are higher than 40%, soil under consideration are not suitable for road construction unless they are stabilized
The average liquid limits of natural clayey soil samples are higher than 40%, soil under consideration is not suitable for road construction unless it is stabilized
Summary
Soft clay soils are recent alluvial deposits presumably formed through the most recent 10,000 years described by their featureless and flat ground surface These soils are wide spread in Mesopotamian Plain in Iraq in its southern part which are characterized by their low bearing capacity and strength besides their low California bearing ratio (CBR) [1]. Soft clays are characterized by their low undrained shear strength and high compressibility Such clays are defined as a disturbed cohesive soil whose water content is higher than its liquid limit, such materials display extremely low yield stresses and represent difficult construction conditions. Such types of clays always bring the problems of soil instability and structure settlement. The present study investigates whether the sawdust ashes (SDA) can be used as an additive to stabilize soft clayey soils by improving their geotechnical properties which will encourage the use of SDA as a stabilizer for clayey soil to solve road failure problems
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