This paper presents the role of clay portion in soil used to stabilize soils during alkaline activation with potassium-based alkaline activator. A 10 M potassium hydroxide solution was utilized to activate the soils with and without palm oil fuel ash (POFA) at a solution. Soils with and without POFA mixtures were tested using unconfined compression tests and microstructural analysis (using scanning electron microscopy and X-ray diffraction). Comparing the strength of the mixtures with and without POFA, the results presented that short-term compressive strength was higher for mixtures with POFA. However, after longer curing the admixtures of higher kaolinite content with POFA reached significantly higher strength levels than the admixtures without POFA. This work brings new insights to the soil stabilization by alkaline activation providing a relatively new avenue for effective utilization of aluminosilicate source materials with parent-treated soils. The clay minerals of hosted soil play an important role in soil stabilization with alkaline activation that affects the behavior of binder with hosted soil.

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This study is directed to the feasibility of usage of palm oil fuel ash (POFA) as a precursor of alkaline activation reactions which made by potassium hydroxide in order to stabilize the soil and improve its expediency for the different case of construction. The effect of duration and temperature of curing, for the alkaline activation process, on the Unconfined Compression Strength (UCS) of the soil-POFA mixture is important in enhancing the treated soil properties. Use of 30, 50, and 100°C of heating affected the UCS of the soil mixture. The highest strengths were obtained at 100°C for the alkali activation process. Microstructural analysis using The Brunauer-Emmett-Teller (BET) and Infrared spectrometric analysis (FTIR) shows the benefits of alkaline activation in terms of decreasing the duration of the alkaline process. The pore distribution analysis showed a trend to rise pore size volume with increasing temperature, which affects the mechanical characteristics. This was due to the fastest crystallization processes which account for strength gain after a short period of heating. It has been also presented the opportunity of observing the alkaline activation process by FTIR Spectra. This paper highlights a more environmentally friendly procedure of stabilizing soils compared with the traditional binders such as cement and lime.

In this paper the potential of introducing alkali activated fly ash to a clayey soil as stabilizing agent was investigated. As alkaline activator Potassium hydroxide of 12 M was introduced to the soil fly ash mixtures. Unconfined compressive strength tests were carried out. Four different fly ash/solid ratios were proposed to be 10 %, 20 %, 30 % and 40 % at two curing regimes of 7 & 28 days. The highest unconfined compressive strength was of 40 % mixture recorded at 3.68 MPa after 28 days. Alkaline activation of clayey soil using KOH solution as an activator proved to be a feasible alternative for soft soil stabilization.