Experimental analysis of soil stabilization using e-waste

Materials Today: Proceedings xxx (xxxx) xxx

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Experimental analysis of soil stabilization using e-waste J. Kiran Kumar, V. Praveen Kumar Saveetha School of Engineering, SIMATS, Chennai, India

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Article history: Received 7 May 2019 Received in revised form 27 July 2019 Accepted 30 July 2019 Available online xxxx Keywords: E-waste Environment Soil Geotechnical Shear strength

a b s t r a c t The production of electronic waste is rapidly increasing with the updates in technological world being developed on a daily basis, making the predecessors obsolete. Improper handling of e-waste has made it a major contributor towards waste generation and a potential threat to the environment. This study is aimed at providing two solutions, one towards soil stabilization and second towards handling e-waste effectively. This paper focuses on using the e-waste, processed in a powdered form along with soil and comparing the improvement in geotechnical properties. Tests were conducted to identify the properties of materials being used in this study, and also over combination of soil with e-waste at different percentages such as 3, 6, 9 and 12. Apart from basic soil tests, the samples were subjected to shear strength, unconfined compression and CBR tests. Results indicate a healthy increase in properties like shear strength, stability of the soil against failure of slopes. Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials Engineering and Characterization 2019.

1. Introduction Enhancing the geotechnical properties of soil with additives is generally termed, stabilization of soil. The strength and bearing intensity of the soil, being vital engineering properties is improved significantly by controlled compaction and addition of renewable agents like enzymes, biopolymers etc. E-waste generated contains a major portion of discarded PCB (Printed Circuit Boards). Estimates of 50 millions of e-waste are being generated every year and improper handling makes the environment unstable. With the use of renewable agents being exhausted, the quantity of e-waste being generated makes it a suitable additive to soil matrix. Previous studies were carried out using e-waste along black cotton soil in minimizing the swelling, but the use of e-waste along sandy soil is not being much researched into. E-waste stabilization helps in expanding the quality, strength and furthermore limits the moisture content in the soil sample. E-waste must be compacted for obtaining required strength and quality by referring to optimum moisture content. Nature of E-waste to be included relies on the particular surface zone of soil particles. Cohesion-less soil are critical in terms of designing structures and especially in tropical nations like India, having wide variation in temperatures prompting wide varieties in dampness content of soils. Issues like high compressibility, swelling, shrinkage accompany the cohesion less soil, forcing addition of stabilizing agents. This study uses a non-conventional method by

adding e-waste along the soil sample in a powdered form. Shredded PCB’s are used at different percentages such as 3, 6, 9 and 12 with the soil sample and basic tests were carried out. Tests mainly focus on increasing the shear strength, bearing capacity and stability against failure of slopes with addition of e-waste.

2. Literature study Chatterjee and Kumar [5] focuses on the importance of recycling E-waste among different sectors which forms the scope of current project work. This study gives a wide area of electronic waste generation under Indian conditions, emphasizing the importance of using E-waste, thereby reducing the stagnation of waste among the surroundings. Li et al. [6] emphasizes on the importance of handling E-waste and its effects over environment if not disposed off with proper precautions. This study serves as a base for using E-waste in stabilizing soil as the study mainly focuses on soil contamination of E-waste. Findings from the study will enable to identify the quantity of E-waste material to be added to the soil sample. Karthik et al. [1] used the fly ash material as a stabilising agent in soil sample at 3, 5, 6 and 9%.The CBR valued showed an increase in its value with the addition of fly ash and also emphasized in using it for a sub grade material. This paper showcases the importance in improving the soil properties for a sub grade material. Yilmaz et al. [8] experiments the use of wastes from stone

https://doi.org/10.1016/j.matpr.2019.07.716 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Materials Engineering and Characterization 2019.

Please cite this article as: J. Kiran Kumar and V. Praveen Kumar, Experimental analysis of soil stabilization using e-waste, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.07.716

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industry as a stabilising agent in soil to improve its nature against freezing and thawing effect. The waste material infused soil sample is tested for its unconfined compressive strength and the results show a significant decrease in the value after freezing thawing cycles. The unconfined compressive strength shows an increase of 100% when compared to the conventional sample also exhibits a potential development in stabilizing properties of the soil. Adams Joe and Maria Rajesh [3] used industrial waste in stabilising the soil. The waste included copper slag, cement and lime. Tests such as atterberg’s limits, proctor compaction, California bearing ratio were conducted over the soil sample. The results indicate the addition of lime and industrial wastes in the soil, increases the compressive strength when compared with ordinary soil sample. The findings of this study indicate improvement in index properties and other geotechnical properties and also emphasize in cost reduction in Ground improvement techniques. Gupta and Raghuwanshi [9] carried out a stabilization technique over black cotton soil, where PCB wastes are mixed with Black cotton soil sample at different ratios such as 3, 6, 9 and 12% and tests were carried out. The objective of this study was to analyze the use of e-waste on expansive soils for embankments and pavement constructions. The Geotechnical properties of the stabilized soil sample were graphically compared and the results show an improvement in all properties. The results indicate that the maximum dry density and optimum moisture content for the soil sample mixed with e-waste were found to be optimum at 6% and attained higher CBR value at the same percentile. Upadhyay and Kaur [2] identified that with addition of ceramic waste, index properties like liquid limit and plastic limit showcased an detrimental effect and addition of electronic waste exhibited and increase in the same. Afrin [7] focuses on the chemical and mechanical properties of the stabilized soil. Different techniques for stabilization of soil were reviewed in this study. Factors such as organic matter, sulphates, sulphides, compaction, moisture content and temperature were analyzed upon. The study concluded the importance of using chemical agents for stabilizing the soil and performance based testing methods. Dinesh et al. [4] reviewed on all the study carried out till date on stabilising the soil. This paper gives an ideas of the wastes used for improving the soil properties and also shows that E-waste hasn’t been used in this soil stabilization techniques. Tests like California bearing ratio, atterberg’s limits and other properties were being discussed upon.

Table 2 Sieve analysis. Sieve size

Weight of soil retained in sieve (in grams)

Uniform cumulative (grams)

Percentage

4.75 mm 2.36 mm 1.7 mm 1.18 mm 600 m 450 m 300 m 150 m 75 m Pan

440 25 22 3 5 3 0 2 0 0

500 60 35 13 10 5 2 2 0 0

100 12 7 2.6 2 1 0.4 0.4 0 0

Table 3 Soil physical characteristics. Properties

Average values

Natural moisture content Specific gravity Dry unit weight Natural unit weight Porosity Void ratio Liquid limit Plastic Limit

17.84% 2.67 18.12 kN/m3 21.35 kN/m3 0.31 0.45 12.76 25

Specific gravity 1.16 1.14 Specific Gravity

2

1.12 1.1 1.08 1.06 1.04 1.02 8%

6%

12%

15%

Soil sample Fig. 1. Graphical comparison of specific gravity of soil with different percentages of e-waste.

3. Materials and methods

3.2. Soil

3.1. E-Waste

Soil sample obtained is analysed for various properties and the results are shown in Table 2. Basic tests like specific gravity, moisture content, atterberg’s limits and particle size distribution were carried out. These values pave way for further study along the soil sample infused with e-waste. The sample is obtained from a site near Chembarambakkam, Tamil Nadu at a depth of 1 m (Table 3).

This is obtained by reducing the PCBs into a powdered form of fine nature. Printed Circuit Boards (PCB) constitute around three times the amount of waste generated. PCB’s generally constitute layers of copper and epoxy materials stacked up in layers. The properties of this material are tabulated below after carrying out basic tests as shown in Table 1. The particle size distribution test is carried out for this material and the results are shown in Table 2.

3.3. Methods Different tests were carried out to analyse and compare the properties of soil infused with e-waste.

Table 1 E-waste properties. Properties

Average values

Natural moisture content Specific gravity Dry unit weight Natural unit weight Porosity Void ratio

18% 1.25 10.01 kN/m3 8.483 kN/m3 0.183 0.225

Table 4 Specific gravity of the test samples. Proportions of e-waste added to soil

Specific gravity

6% 8% 12% 15%

1.064 1.112 1.145 1.08

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3%

6%

9%

3.3.2. Liquid limit The comparison of liquid limits of soil samples with e-waste are shown in the figure below (Fig. 2).

12%

70%

Liquid limit

60% 50% 40% 30% 20% 10% 0% Fig. 2. Liquid limit values of soil with e-waste.

3.3.1. Specific gravity The soil sample was mixed with e-waste at proportions such as 6, 8, 12 and 15% to compare the specific gravity of the samples. Table shows the specific gravity values for different mixes and the results are graphically plotted (Fig. 1 and Table 4).

3.3.3. Unconfined compressive strength This is to measure the materials strength in one direction. The soil sample with proportions of e-waste at 3, 6 and 9% were subjected compressive forces uniaxially and the results obtained as shown in the table below. Graphical comparison of the stress strain curve obtained from the test as shown in the Fig. is used for identifying the optimum mix of e-waste in soil (Table 5 and Fig. 3). 3.3.4. Direct shear test The shear strength of the soil along with e-waste at different proportions are analysed by conducting direct shear tests and graphically compared. The test results are shown in the table below (Table 6 and Fig. 4).

Table 5 Unconfined compressive strength values of test samples. 3%

6%

9%

Strain

Stress (N/mm2)

Strain

Stress (N/mm2)

Strain

Stress (N/mm2)

0 0.66 1.315 1.973 2.631 3.289 3.947 4.605

0 0.413 1.02 2.242 3.037 3.218 3.995 4.96

0.66 1.315 1.973 2.631 3.289 3.947 4.605 5.263

0.558 0.831 1.3 2.18 2.71 3.23 3.75 4.5

0.66 1.315 1.973 2.631 3.289 3.947 4.605 5.263

0.836 2.216 3.85 6.014 6.78 8.36 9.1 10.1

Fig. 3. Comparison of Unconfined compressive strength values.

Table 6 Direct shear test values of test samples. 3% of E-Waste

6% of E-Waste

9% of E-Waste

Normal stress (kg/cm2)

Ultimate shear stress (kg/cm2)

Normal stress (kg/cm2)

Ultimate shear stress (kg/cm2)

Normal stress (kg/cm2)

Ultimate shear stress (kg/cm2)

1.3 3.1 5.2

0.975 1.275 1.575

1.3 2.8 4.8

1.35 1.8 2.175

1.3 3.3 6

2.1 2.4 2.885

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Fig. 4. Direct shear test values.

4. Conclusion

References

It has been seen that Liquid limit of the sample increases with percentage of addition of E-Waste. The ideal dry density and the unconfined compressive strength of the soil sample were found to be at 6% addition of E-waste by weight of soil. Optimum moisture content increased gradually with addition e-waste at 6% by weight. Decrement in plastic limit was observed till the addition of 6% of E-waste and further addition made it non plastic in nature. The test results show a maximum value for shear strength and 60% increases in value in direct shear testing with addition of 6% of E-Waste along the soil samples. The unconfined compressive strength also showed an increase of about 56% when compared to conventional soil samples without E-Waste. It has been discovered that there is a most extreme improvement in quality properties for the mix of E-Waste with cohesion-less soil. This finds an application for mechanical waste to improve the properties of broad soil both in banks and asphalt developments. E-Waste has great potential for use in geotechnical application of soils is a demonstrated technique to spare time and cash on development ventures. The present examination can fill in as a viable strategy to use E-Waste in par with cohesion-less soil. Addition of E-waste not only increases the properties but also makes it a minor threat to the environment. This papers exhibits that utilisation of Ewaste at different percentages stabilises the soil as well as the waste has been handled effectively.

[1] S. Karthik, E. Ashok Kumar, P. Gowtham, G. Elango, D. Gokul, S. Thangaraj, Soil stabilization by using fly ash, J. Mech. Civ. Eng. 10 (2014) 20–26, E-Issn:22781684, P-Issn:2320-334x. [2] Ajay Upadhyay, Suneet Kaur, Review on soil stabilization using ceramic waste, Int. Res. J. Eng. Technol. 03 (07) (2016), E-ISSN: 2395 -0056, P-ISSN: 2395-0072. [3] M. Adams Joe, A. Maria Rajesh, Soil stabilization using industrial waste and lime, Int. J. Sci. Res. Eng. Technol. 4 (7) (2015), ISSN 2278 – 0882. [4] A. Dinesh, S. Gokilavani, G. Ramya, Stabilization of soil by using solid waste – a review, IJEDR 5 (4) (2017), ISSN: 2321-9939. [5] S. Chatterjee, Krishna Kumar, Effective electronic waste management and recycling process involving formal and non-formal sectors, Int. J. Phys. Sci. 4 (13) (2009) 893–905, ISSN 1992 - 1950 Ó 2009 Academic Journals. [6] Jinhui Li, Huabo Duan, Pixing Shi, Heavy metal contamination of surface soil in electronic waste dismantling area: site investigation and source-apportionment analysis, Waste Manage. Res. 29 (7) (2011) 727–738, https://doi.org/10.1177/ 0734242X10397580. [7] Habiba Afrin, A review on different types soil stabilization techniques, , Int. J. Transp. Eng. Technol. 3 (2) (2017) 19–24, https://doi.org/10.11648/J.Ijtet. 20170302.12. [8] F. Yilmaza, H.A. Kamilog˘lua, E. Sßadog˘lub, Soil stabilization with using waste materials against freezing thawing effect, in: International Conference On Computational And Experimental Science And Engineering (ICCESEN 2014), 2014. [9] Rahul Gupta, Anand Kumar Raghuwanshi, Utilization of e-waste in strength enhancement of black cotton soil, J. Environ. Sci. Eng. 1 (3) (2016).

Further reading [10] Ali, Sunil Koranne, Performance analysis of expansive soil treated with stone dust and fly ash, 16 (2011) Bund. I.

Please cite this article as: J. Kiran Kumar and V. Praveen Kumar, Experimental analysis of soil stabilization using e-waste, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.07.716