The Experimental and Statistical Study of the Mechanical Properties of Geopolymeized Soil Along with Weathering Resistivity

Abstract

The emerging trend in civil engineering involves incorporating geopolymer into soil amendments. This experimental investigation involved the preparation of composite samples by blending soil, ground granulated blast furnace slag (GGBS), red mud (RM), and phosphogypsum, activated using a sodium-based alkali solution. A series of mechanical and durability tests were conducted to identify the optimal sample for further evaluation. Utilizing a statistical approach, analysis of variance was applied to ascertain the optimal mix design and evaluate the sensitivity of RM, GGBS, and chemicals to strength characteristics. The maximum unconfined compressive strength obtained was 12.08 MPa after 28 days of curing, representing a significant increase of 140 times compared to the original soil, with a 55% soil replacement by weight. As GGBS increased and soil content decreased in the matrix, the composite exhibited brittle behaviour during failure. Weathering resistance was evaluated through wet-dry cycles and submergence in a sulphuric acid solution. It was noticed that structural integrity was achieved by using both sodium silicate and sodium hydroxide. The findings highlighted the crucial role of GGBS among the by-products in enhancing strength and preserving structural integrity. Statistical analysis, with a p-value significantly below 0.05, confirmed the model’s alignment with laboratory results. To gain a comprehensive understanding of the material, the surface morphology and diffractogram of the composite were analysed using scanning electron microscopy and X-ray diffractogram, revealing structural and morphological changes in the geopolymer-bonded soil.

Graphical Abstract