Geopolymerisation and micro-pore assessment of soft soil used as flexible pavement material in road construction

Abstract

In this study, inexpensive dual precursors namely rice husk ash (RHA) and quarry dust (QD) were mixed with an alkali solution (NaOH solution) in different mix proportions. Next, the effect of the dual precursors-alkali solutions (geopolymers) on the strength parameters of the different soil-geopolymer mixes subjected to various curing days were assessed. The result obtained from the assessment showed that the dual precursors-alkali solutions improved the strength properties of all the different soil-geopolymer mixes. The optimum soil-geopolymer mix proportion that resulted in the best improvement of the expansive subgrade soil properties was observed at a combination of 15%RHA+15%QD+3M NaOH. Furthermore, micro-pore analyses (porosity and pore size distribution), which were implemented with scanning electron micrographs and an image segmentation technique, local adaptive thresholding algorithm, showed progressive reduction in the porosity of the natural expansive subgrade soil and that of the optimal soil-geopolymer mix proportion cured for 7 and 28 days.

KEYWORDS:

• Expansive subgrade soil
• flexible pavement construction
• geopolymerisation
• image segmentation technique
• local adaptive thresholding

Acknowledgements

The first author of this paper expresses a sense of gratitude to his undergraduate supervisees, Stephen Eke Kalu and Chibuike Nnammani, for their immense contribution to the collection of the soil sample and also for their unquantifiable assistance in the execution and timely completion of the experimental programme.

Disclosure statement

No potential conflict of interest was reported by the authors.