Durability of Lime-Fly Ash Stabilized Soil Activated by Calcined Phosphogypsum

Abstract:

Stabilized soil is widely used as road base and sub-base materials, and is sometimes used as covering for waste matter in China. In soil stabilization, the property of a locally available soil are usually modified though chemical stabilization[1]. Cement stabilization and lime stabilization are the two most commonly used methods. Lime-fly ash stabilized soil has been widely applied in road engineering due to its good integrity, great bearing capacity, high stiffness, and water-proofing quality[2-4]. One disadvantage of lime-fly ash stabilized soil is that without any additives, its inherent low initial strength makes it inappropriate for use under low-temperature conditions. Researchers have found that the pozzolanic reactivity among lime, fly ash, and soil contributes to the strength of lime-fly ash stabilized soil. To increase the initial strength of lime-fly ash stabilized soil, many approaches have been used to accelerate the pozzolanic reaction. Sulfate activation is one of the methods that has been widely investigated, specifically, Na2SO4 and CaSO4[5]. PG, another sulfate, has also been investigated. However, existing studies have limited to the investigation of the development of strength of the stabilized soil as road base and sub-base materials. The effect of PG on the durability of stabilized soil has rarely been implicated. This work aims to study the effect of thermally treated PG (400°C) on the properties of durability, in addition to other aspects, of lime-fly ash stabilized soil. Lime-fly ash stabilized soil with different proportions of calcined PG were prepared and cured at normal conditions for 7 d and 28 d. Mass loss and strength loss under different treatments were determined. X-ray diffraction(XRD) patterns and scanning electron microscopy(SEM) photos were examined to gauge whether improvements in the performances of the stabilized soil can be obtained by use of thermally treated PG.

• Periodical: Advanced Materials Research (Volumes 168-170)
• Pages: 133-138
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.168-170.133
• Online since: December 2010
• Authors: Min Yang, Yan Xie, Ying Pang
• Keywords: Activation, Durability, Lime-Fly Ash Stabilized Soil, Phosphogypsum (PG)

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