An Experimental Study on Stabilization of Expansive Soil using Metakaolin and Ground Granulated Blast Furnace Slag

Abstract

Expansive soils pose significant challenges to civil engineering structures due to their high shrink–swell behavior under varying moisture conditions. This study investigates the stabilization of expansive soil using metakaolin and Ground Granulated Blast Furnace Slag (GGBS) as sustainable stabilizing agents. Metakaolin and GGBS were initially added individually at proportions of 5%, 10%, 15%, and 20% by dry weight to evaluate their influence on engineering properties. Based on laboratory results, the optimum metakaolin content was identified as 15%. Subsequently, GGBS was incorporated at 10%, 15%, 20%, and 25% along with the optimum metakaolin content to examine the combined effect. Laboratory tests included Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), and California Bearing Ratio (CBR). The results showed a reduction in plasticity and a significant improvement in strength characteristics. The optimum performance was observed at 15% metakaolin and 15% GGBS. The study demonstrates that the combined use of metakaolin and GGBS is an effective and sustainable approach for improving expansive soil.

Introduction

The document discusses the problem of expansive soils in geotechnical engineering, which undergo significant shrink–swell behavior due to moisture changes, causing damage to structures such as pavements and foundations. To address this issue, the study explores sustainable soil stabilization techniques using industrial by-products like metakaolin and Ground Granulated Blast Furnace Slag (GGBS), aiming to improve soil strength, reduce plasticity, and enhance durability in an eco-friendly and cost-effective way.

The research focuses on evaluating the individual and combined effects of metakaolin and GGBS on expansive soil collected from Tirupati district. The soil is highly plastic, highly swelling, and weak in strength, making it suitable for stabilization studies. Laboratory tests such as Atterberg limits, compaction (OMC and MDD), Unconfined Compressive Strength (UCS), and California Bearing Ratio (CBR) were conducted to assess improvements in engineering properties.

Metakaolin improves soil behavior through pozzolanic reactions, reducing plasticity and increasing strength, while GGBS contributes cementitious properties that enhance durability and load-bearing capacity. Various mix proportions were tested to identify optimal stabilization levels, both individually and in combination.

The literature review highlights that both materials are effective independently, but limited research exists on their combined synergistic effect, which this study addresses.

Conclusion

The present study demonstrates that stabilization of expansive soil using metakaolin (MK) and Ground Granulated Blast Furnace Slag (GGBS) significantly improves its engineering properties. The addition of MK and GGBS reduces plasticity and enhances soil consistency due to pozzolanic and cementitious reactions. The unconfined compressive strength (UCS) and California Bearing Ratio (CBR) values show substantial improvement, with optimum performance observed at 15% MK and 15% GGBS. Beyond this optimum level, a slight reduction in strength is observed due to excess unreacted material and increased voids. Microstructural analysis confirms the formation of cementitious compounds such as C–S–H and C–A–S–H, which enhance bonding, densification, and strength development. Overall, the combined use of MK and GGBS is an effective and sustainable method for improving expansive soil, making it suitable for pavement subgrade applications.

References

[1] U. Abubakar and K. S. Baharudin, “Potential use of Malaysian thermal power plants coal bottom ash in construction,” International Journal of Sustainable Construction Engineering & Technology, vol. 3, no. 2, 2012. [2] R. Adon, I. Bakar, D. C. Wijeyesekara, and A. Zainorabidin, “Overview of the sustainable uses of organic soft soil in Malaysia,” International Journal of Integrated Engineering, vol. 4, no. 3, pp. 38–46, 2012. [3] A. Al-Tabbaa, “Soil mixing in the UK 1991–2001: State of practice report,” Ground Improvement, vol. 7, no. 3, pp. 117–126, 2003. [4] A. Farouk and M. Shahien, “Ground improvement using soil–cement columns: Experimental investigation,” Alexandria Engineering Journal, vol. 52, pp. 733–740, 2013. [5] A. R. Goodarzi and M. Salimi, “Stabilization treatment of dispersive clay using blast furnace slag,” Applied Clay Science, vol. 108, pp. 61–69, 2015. [6] D. D. Higgins, “Soil stabilisation with ground granulated blast furnace slag,” UK Cementitious Slag Makers Association, 2005. [7] H. Jafer, W. Atherton, and F. Ruddock, “Soft soil stabilisation using high calcium waste materials,” in Proc. Int. Post-Graduate Research Conf., pp. 147–157, 2015. [8] M. Kitazume and M. Terashi, The Deep Mixing Method. CRC Press, 2013. [9] S. Kazemian et al., “Settlement problems in peat due to high compressibility,” in Proc. Forensic Engineering Congress, 2009. [10] A. Z. Kifli et al., “Physical properties of peat soil,” in Proc. Soft Soils, 2016. [11] N. Kumar and S. S. Kazal, “Improvement of subgrade strength using lime and rice husk ash,” International Journal of Engineering, vol. 14, no. 1, pp. 1–5, 2015. [12] G. P. Makusa, Soil Stabilization Methods and Materials in Engineering Practice, M.S. thesis, Luleå University, 2012. [13] S. Sharma and M. Sivapullaiah, “Ground improvement using metakaolin,” Construction and Building Materials, vol. 200, pp. 679–690, 2019. [14] M. Kumar and A. Gupta, “Effect of GGBS on strength behavior of clay soils,” Journal of Materials in Civil Engineering, vol. 32, no. 5, 2020. [15] A. Singh and R. Kumar, “Stabilization of expansive soil using industrial by-products,” Materials Today: Proceedings, vol. 43, pp. 123–130, 2021. [16] P. Reddy and K. Rao, “Combined effect of metakaolin and GGBS on soil stabilization,” International Journal of Geotechnical Engineering, 2022. [17] V. Patel et al., “Sustainable soil stabilization using GGBS and metakaolin,” Case Studies in Construction Materials, vol. 17, 2023. [18] S. Mishra and A. Dhawan, “Effect of metakaolin on engineering properties of expansive soil,” International Journal of Civil Engineering, 2019. [19] R. Verma and P. Singh, “Utilization of GGBS for soil stabilization,” International Journal of Engineering Research & Technology, 2020. [20] K. R. Murthy and B. V. Reddy, “Behaviour of stabilized clay using industrial waste materials,” Materials Today: Proceedings, 2021. [21] A. K. Sharma and R. S. Gupta, “Experimental investigation on expansive soil stabilized with GGBS,” Geotechnical and Geological Engineering, 2022. [22] P. S. Raju and M. S. Kumar, “Strength characteristics of stabilized soil using pozzolanic materials,” International Journal of Pavement Engineering, 2023. [23] T. Ramesh and K. S. Prasad, “Performance of metakaolin in soil stabilization,” Journal of Civil Engineering Research, 2020. [24] N. Patel and S. Shah, “Effect of industrial by-products on soil stabilization,” Construction Materials Journal, 2021. [25] D. Singh and A. Verma, “Improvement of subgrade soil using GGBS and metakaolin,” International Journal of Engineering Sciences, 2024.

Copyright

Copyright © 2026 V. Priyanka, K. Venkata Bhargav, K. Mallikarjuna Rao. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.