Strengthening Montmorillonitic and Kaolinitic Clays Using a Calcium-Based Non-Traditional Additive: A Micro-Level Study
Nima Latifi1; Christopher L. Meehan2; Muhd Zaimi Abd Majid3; Suksun Horpibulsuk4
1Post-Doctoral Researcher, University of Delaware, Dept. of Civil and Environmental Engineering, 301 DuPont Hall, Newark, DE 19716, U.S.A.
E-mail: nlatifi@udel.edu (corresponding author)
2Bentley Systems Incorporated Chair of Civil Engineering & Associate Professor, University of Delaware, Dept. of Civil and Environmental Engineering,
301 DuPont Hall, Newark, DE 19716, U.S.A.
E-mail: cmeehan@udel.edu (corresponding author)
3Professor, Institute for Smart Infrastructure and Innovative Construction (ISIIC), Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.
E-mail: mzaimi@utm.my
4Professor, School of Civil Engineering and Center of Excellence in Civil Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
E-mail: suksun@g.sut.ac.th
Applied Clay Science, 2016, Volume 132-133, pp. 182-193
Abstract
Chemical stabilization of clays is commonly used to improve unfavorable engineering properties. Though the effects of non-traditional additives on soil improvement have been investigated in recent years, documented research studies on the macro- and micro-level characteristics of problematic clays stabilized by non-traditional additives are fairly limited. The current study examines the time-dependent changes induced in the strength, mineralogy, morphology, molecular and micro-fabric characteristics of montmorillonitic and kaolinitic clays stabilized with a non-traditional calcium-based additive, which is commercially available under the product name SH-85. The physico-chemical bonding mechanisms induced by the stabilization process were studied at a micro-level using various spectroscopic and microscopic techniques, such as X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometry (EDAX), Fourier transform infrared spectroscopy (FTIR), Brunauer, Emmett and Teller (BET) surface area analysis and particle size analysis (PSA) using a laser diffraction approach. Unconfined compressive strength (UCS) tests were also performed on stabilized specimens at various curing times to examine macro-level characteristics. The UCS test results showed that the 6% and 9% additive content were optimal for montmorillonitic and kaolinitic clays, respectively, with the UCS of both stabilized clays improving significantly after 7 days of curing. This relatively rapid curing reaction process is very advantageous and cost-effective for geotechnical engineering applications. The micro-level study revealed that the calcium-based additive modified the porous network of the stabilized clays. The pores were filled and particles were bonded by cementitious products, including calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H) for the stabilized montmorillonitic and kaolinitic clays, respectively.
Keywords
Non-traditional additive; Montmorillonitic clay; Kaolinitic clay; Unconfined compressive strength (UCS); Field emission scanning electron microscopy (FESEM); Fourier transform infrared spectroscopy (FTIR)
Reference
Latifi, N., Meehan, C. L., Abd Majid, M. Z., and Horpibulsuk, S. (2016). “Strengthening Montmorillonitic and Kaolinitic Clays Using a Calcium-Based Non-Traditional Additive: A Micro-Level Study.” Applied Clay Science, Elsevier, 132-133, 182-193. (doi:10.1016/j.clay.2016.06.004)