Model Study of Alkali-Activated Waste Binder for Soil Stabilization

Abstract

This study assesses the laboratory investigation to evaluate the feasibility of using alkaline activation technique for engineering improvement of soils. The originality of this paper stems from the novel two-stage approach. The first stage investigates the effectiveness of locally available precursor in the alkaline activation process by focusing on soil strength improvement. As such, in presence of high alkali solutes (Na-based and Ka-based alkaline activators), palm oil fuel ash (POFA) was used as a precursor due to its amorphous nature and high silica-toalumina ratio. In the second stage of this study, geotechnical model procedure of interaction between a strip footing model and stabilized soil by column technique and the most effective percentage of POFA was performed. According to the test results, applying alkaline activators to soil induced low strengths of up to 159 kPa after 7 days curing. When the POFA content used in alkaline activation increased from 0 to 15%, the UCS values increased up to 226% after similar curing duration. This assertion reflects the fact that the addition of POFA enriched the reactive Si and Al in the matrix, which allowed stronger Si-O-Si and Al-O-Si bonds to form. Curing condition, type and quantity of the alkaline activators were also shown to have significant strengthening effects on the treated soil. In this respect, the use of moderate 10 M NaOH and 10 M KOH were found to be viable as the best concentration for strength improvement of investigated soil when economy and practicality were considered. In terms of using alkali-activators, the use of the NaOH for soil treatment is beneficial in terms of lower cost, since the price of KOH solution is higher than that of the NaOH solution. Results of the second phase showed that a considerable settlement reduction up to 192% of treated columns by means of alkaline activation could be achieved.

Alkaline Activation of Clayey Soil Using Potassium Hydroxide & Fly Ash

“…At between higher wave numbers of 1600 cm -1 ,1751 cm -1 and 2762 cm -1 , 4000 cm -1 for both of S1F and S1FR two main broad peaks of 1651 cm -1 and 3622 cm -1 with low intensities of 2% were observed indicating stretching and deformation vibrations of OH and H-O-H groups from the weakly bound water molecules, which were adsorbed on the surface or trapped in the cavities between the framework bonds of the activated specimen. These observations were similar to those reported by plenty of researchers [7][8][9][10][11][12][13][14][15][16][17].…”

“…Variety of research works have addressed the feasibility of introducing the aforesaid binder to remediate problematic soils. Their results drawn confirmed high stiffness and durability of treated soft soils [7][8][9][10][11][12][13][14][15]. Though, the alkaline activator used by the above mentioned trials was either Sodium hydroxide, a mix of Sodium hydroxide and Sodium silicate or a mix of Potassium hydroxide and Potassium silicate.…”

“…Although a Si/Al ratio above 2 was reported to indicate an optimum compressive strength gain [10], the rate of strength evolution over 28 days is substantial. The reason behind might be the increasing fly ash content present in the matrix, that contributed to a drastic increase in the compressive strength of the treated soil [8][9][10][11][12][13][14]. Fourier transform infrared spectroscopy (FTIR) was conducted to characterize the different bonds with short-range structural order for KSF as depicted in fig.…”

Clayey soil stabilization using geopolymer and Portland cement

“…However, a higher early strength was observed when FA-geopolymer soil was cured at higher temperatures [22,23]. The compressive strength of POFA-geopolymer soil which subjected to hot curing was increased by 112% in comparison with that of cured in the absence of the heating process [24].…”

Characterization and finite element analysis of lime and polymer treated ultra-soft clay soils using the electrical resistivity and miniature penetrometer methods

“…Soft clay deposits are located in many coastal areas and they exhibit poor strength and compressibility (Pourakbar et al, 2016). Various soil improvement methods have been used for improving the shear strength of soft clays.…”