Sawdust Effect on Compressibility and Shear Strength Characteristics of Highly Organic Clay

Abstract

Organic soils are known for their low shear strength and high compressibility, making them unstable and unsuitable for supporting foundations with instability problems such as local sinking, development of slip failure, excessive settlement, and bearing capacity failure. Thus, such soils need improvement prior to construction to suit the infrastructure projects. Several improvement techniques are available depending on the thickness of the organic deposit, type, and characteristics. The stabilization technique is one method that is considered economical, functional, and environmentally friendly; it is the process of changing the chemical properties of soil by adding stabilizers in wet or dry conditions such as lime, fly ash, cement, sawdust, or sawdust ash to increase the shear strength, decrease the compressibility and permeability of the soil. In the current study, an experimental effort investigates the effect of mixing sawdust with highly organic clays. In the presence of moisture, sawdust, widely available and economical, reacts chemically, forming cementations compounds that improve soils' strength and compressibility properties. Highly organic clay samples from Kafr El Sheikh Governorate, Egypt, were mixed with 5 % cement and varying percentages of sawdust by weight. Samples are cured for seven days before conducting shear strength and compressibility tests. The tests include laboratory shear vane, direct shear, and one-dimensional oedometer tests. The results provide insight into the use of sawdust in improving the strength and deformation properties of the tested organic clay.

Use of Sawdust Fibers for Soil Reinforcement: A Review

“…It showed that the best results in the shear strength tests were obtained for a combination of 5% cement with 15% sawdust. While the combination of cement and sawdust gives better consolidation, the results are 5% cement with 10% sawdust [39]. Another study conducted in Pakistan analyzed the effect of the addition of variable percentages of the mixture of rice husk (0 to 21%) and sawdust (0 to 7%) applied to clay soil, mitigating their erosive potential and improving their parameters of shearing strength for the use on earthen embankments, observing that 5% sawdust and 15% rice husk are established as the optimal content for effective stabilization, and soil erosion control studied [112].…”

“…In some cases, the improvements reached by these techniques are not required, i.e., in subgrade road projects [38,39], leading to the identification of cheaper materials as alternatives [15].…”

Use of Sawdust Fibers For Soil Reinforcement: A Review

“…On the other hand, it is possible that the high strength obtained with these techniques is not always required, as is the case of subgrades in road projects [38,39], and there is a justification for looking for cheaper additives that can be used to improve soil properties [15].…”

“…In Australia, the effect of the addition of sawdust powder on the cohesion of yellow sand was analyzed, varying percentages from 3 to 10% observing a decrease in MDD and angle of friction while OMC and cohesion value increased concerning the increase of sawdust added [104]. Other research carried out in Egypt, studied the effects of adding sawdust on the compressibility and shear strength characteristics of an organic clay from the city of Kafr Elsheikh where 5% cement was mixed with variable percentages of sawdust from 10 to 20%, it showed that the best results in the shear strength tests were obtained for a combination of 5% cement with 15% sawdust, while the combination of cement and sawdust gives better consolidation, the results are 5% cement with 10% sawdust [39]. Another study conducted in Pakistan analyzed the effect of the addition of variable percentages of the mixture of rice husk (0 to 21%) and sawdust (0 to 7%) applied to clay soil, mitigating their erosive potential and improving their parameters of shearing strength for the use on earthen embankments, observing that 5% sawdust and 15% rice husk are established as the optimal content for effective stabilization, and soil erosion control studied [112].…”