Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural Biopolymers
Natural biopolymers offer a sustainable alternative for improving soil behavior due to their inert nature, small dosage requirement, and applicability under ambient temperatures. This research evaluates the efficacy of natural biopolymers for ameliorating an expansive soil by using a 0.5% dosage of...
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| Format: | Article |
| Language: | English |
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MDPI AG
2024-03-01
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| Series: | Geotechnics |
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| Online Access: | https://www.mdpi.com/2673-7094/4/1/17 |
| _version_ | 1797240852426260480 |
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| author | Ahmed Bukhary Shahid Azam |
| author_facet | Ahmed Bukhary Shahid Azam |
| author_sort | Ahmed Bukhary |
| collection | DOAJ |
| description | Natural biopolymers offer a sustainable alternative for improving soil behavior due to their inert nature, small dosage requirement, and applicability under ambient temperatures. This research evaluates the efficacy of natural biopolymers for ameliorating an expansive soil by using a 0.5% dosage of cationic chitosan, charge-neutral guar gum, and anionic xanthan gum during compaction. The results of laboratory investigations indicate that the flow through and volume change properties of the expansive soil were affected variably. The dual porosity, characterized by low air entry due to inter-aggregate pores (AEV<sub>1</sub> of 4 kPa) and high air entry due to the clay matrix (AEV<sub>2</sub> of 200 kPa) of the soil, was healed using chitosan and guar gum (AEV of 200 kPa) but was enhanced by the xanthan gum (AEV<sub>1</sub> of 100 kPa and AEV<sub>2</sub> of 200 kPa). The <i>s</i>-shaped swell–shrink path of the soil comprised structural (<i>e</i> from 1.23 to 1.11), normal (<i>e</i> from 1.11 to 0.6), and residual stages (<i>e</i> ranged from 0.6–0.43). This shape was converted into a <i>j</i>-shaped path through amendment using chitosan and guar gum, showing no structural volume change, with <i>e</i> from about 1.25 to 0.5, but was reverted to a more pronounced form by xanthan gum, with <i>e</i> from 1.5 to 1.32, 1.32 to 0.49, and 0.49 to 0.34 in the three stages, respectively. The consolidation behavior of the soil was largely unaffected by the addition of biopolymers such that the saturated hydraulic conductivity decreased from 10<sup>−9</sup> m/s to 10<sup>−12</sup> m/s over a void ratio decrease from 1.1 to 0.6. At a seating stress of 5 kPa, the swelling potential (7.8%) of the soil slightly decreased to 6.9% due to the addition of chitosan but increased to 9.4% and 12.2% with guar gum and xanthan gum, respectively. The use of chitosan and guar gum will allow the compaction of the investigated expansive soil on the dry side of optimum. |
| first_indexed | 2024-04-24T18:14:01Z |
| format | Article |
| id | doaj.art-d786eb5c56fd4f83894071a3cefecb2e |
| institution | Directory Open Access Journal |
| issn | 2673-7094 |
| language | English |
| last_indexed | 2024-04-24T18:14:01Z |
| publishDate | 2024-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Geotechnics |
| spelling | doaj.art-d786eb5c56fd4f83894071a3cefecb2e2024-03-27T13:43:32ZengMDPI AGGeotechnics2673-70942024-03-014132233610.3390/geotechnics4010017Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural BiopolymersAhmed Bukhary0Shahid Azam1Environmental Systems Engineering, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, CanadaEnvironmental Systems Engineering, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, CanadaNatural biopolymers offer a sustainable alternative for improving soil behavior due to their inert nature, small dosage requirement, and applicability under ambient temperatures. This research evaluates the efficacy of natural biopolymers for ameliorating an expansive soil by using a 0.5% dosage of cationic chitosan, charge-neutral guar gum, and anionic xanthan gum during compaction. The results of laboratory investigations indicate that the flow through and volume change properties of the expansive soil were affected variably. The dual porosity, characterized by low air entry due to inter-aggregate pores (AEV<sub>1</sub> of 4 kPa) and high air entry due to the clay matrix (AEV<sub>2</sub> of 200 kPa) of the soil, was healed using chitosan and guar gum (AEV of 200 kPa) but was enhanced by the xanthan gum (AEV<sub>1</sub> of 100 kPa and AEV<sub>2</sub> of 200 kPa). The <i>s</i>-shaped swell–shrink path of the soil comprised structural (<i>e</i> from 1.23 to 1.11), normal (<i>e</i> from 1.11 to 0.6), and residual stages (<i>e</i> ranged from 0.6–0.43). This shape was converted into a <i>j</i>-shaped path through amendment using chitosan and guar gum, showing no structural volume change, with <i>e</i> from about 1.25 to 0.5, but was reverted to a more pronounced form by xanthan gum, with <i>e</i> from 1.5 to 1.32, 1.32 to 0.49, and 0.49 to 0.34 in the three stages, respectively. The consolidation behavior of the soil was largely unaffected by the addition of biopolymers such that the saturated hydraulic conductivity decreased from 10<sup>−9</sup> m/s to 10<sup>−12</sup> m/s over a void ratio decrease from 1.1 to 0.6. At a seating stress of 5 kPa, the swelling potential (7.8%) of the soil slightly decreased to 6.9% due to the addition of chitosan but increased to 9.4% and 12.2% with guar gum and xanthan gum, respectively. The use of chitosan and guar gum will allow the compaction of the investigated expansive soil on the dry side of optimum.https://www.mdpi.com/2673-7094/4/1/17natural biopolymersexpansive soilwater retentionswell–shrinkconsolidation |
| spellingShingle | Ahmed Bukhary Shahid Azam Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural Biopolymers Geotechnics natural biopolymers expansive soil water retention swell–shrink consolidation |
| title | Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural Biopolymers |
| title_full | Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural Biopolymers |
| title_fullStr | Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural Biopolymers |
| title_full_unstemmed | Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural Biopolymers |
| title_short | Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural Biopolymers |
| title_sort | flow through and volume change behavior of a compacted expansive soil amended with natural biopolymers |
| topic | natural biopolymers expansive soil water retention swell–shrink consolidation |
| url | https://www.mdpi.com/2673-7094/4/1/17 |
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