Effect of fly ash on the bearing capacity of stabilised fine sand

Abstract

This paper is concerned with the role of fly ash (FA) content in the California bearing ratio (CBR) values of stabilised sandy soil for geotechnical and geoenvironmental infrastructure. A series of laboratory testsparticle size distribution and CBR tests, were performed. The literature review demonstrates the shortage of research on the stabilisation of sandy material with FA. The main focus of this paper is to establish the optimal quantity of FA content for the stabilisation of this type of soil. A total of 14 distinctive variations of stabilised sand is presented, with three different FA content percentages (5, 10 and 15%), three main curing periods, with durations of 1, 2 and 4 weeks, and a constant cement content of 3%. Some samples were treated with only 3 and 5% cement, with no addition of FA, so that the effect of cement on this particular sand could be observed, and the contribution of the FA alone could be understood. The results obtained are in line with the literature for other types of soil.

Experimental evaluation of kaolin stabilised with class F fly ash

“…The comparison of the improvements obtained with class C and class F FA was presented in the research by Cristelo et al (2012a), concluding that class F FA provides long-term strength three times higher than the one achieved with class C FA. Moreover, Mahvash et al (2017) showed class F FA activated with cement is the optimum stabilisation approach for most soils.…”

“…The conditions and achieved results varied for each type of material, which led us to conclude that different stabilisation conditions are required for different soil types. Consoli et al (2001), Arora and Aydilek (2005), Consoli et al (2011) and Mahvash et al (2017) have studied the effectiveness of class F FA for soil stabilisation and their results demonstrate a successful application of FA to stabilise soils. Arora and Aydilek (2005) compared cement with lime as possible activators for class F FA stabilisation of sandy soil and concluded that cement is a more successful activator than lime.…”

“…Arora and Aydilek (2005) compared cement with lime as possible activators for class F FA stabilisation of sandy soil and concluded that cement is a more successful activator than lime. Consoli et al (2001) and Consoli et al (2011) used lime, while Mahvash et al (2017) used cement as the activator. The comparison of the improvements obtained with class C and class F FA was presented in the research by Cristelo et al (2012a), concluding that class F FA provides long-term strength three times higher than the one achieved with class C FA.…”

“…FA is a solid waste from coal-fired power plants challenging to dispose of and is profusely produced in about 1.2 billion tonnes per year around the world (Harris et al 2019). Furthermore, the traditional disposal method by landfill can lead to contamination of arable lands (Mahvash et al 2017). As soil stabilisation in ground improvement projects requires a large volume of raw materials, utilisation of FA in soil stabilisation has a significant potential to minimise the amount of disposed waste material (Cristelo et al 2013).…”

“…Various studies performed on the influence of FA in stabilising soil showed a positive impact on the strength of the soil for construction purposes. Nonetheless, the type of soil could affect the outcome of FA stabilisation, implying that FA stabilisation with different types of soil needs to be investigated (Mahvash et al 2017). In particular, there is a lack of previous researches on class F FA stabilisation with kaolin, a material that has low construction quality but is often encountered in geotechnical works.…”