Mechanical Properties and Leaching Characteristics of Geopolymer‐Solidified/Stabilized Lead‐Contaminated Soil

Abstract

Ordinary Portland cement (OPC) is widely used in the solidification/stabilization of Pb‐contaminated soils. However, many studies have suggested that the high content of Pb would degrade the mechanical properties of OPC‐solidified/stabilized soils. This paper presents a new binder, geopolymer fine aggregate (GFA), composed of ground granulated blast furnace slag, fly ash, CaO, and Na2SiO3. For comparison, OPC was used as a conventional binder. Mechanical properties and leaching characteristics are typically used to evaluate the effects of binders on solidified/stabilized soils. Nevertheless, limited information on the mechanical properties and leaching characteristics of the GFA‐solidified/stabilized soils is available. This study thus investigated the mechanical properties and leaching characteristics of geopolymer‐solidified/stabilized Pb‐contaminated soil. Unconfined compressive strength test, permeability test, synthetic precipitation leaching procedure, simplified bioaccessibility extraction, phytoavailability extraction (with diethylene‐triamine penta‐acetic acid), sequential extraction procedure, mercury intrusion porosimetry, and scanning electron microscopy (SEM) were performed on OPC‐ and GFA‐solidified/stabilized soil. The results showed that the GFA presented a better effect on the mechanical properties and leachability of the solidified/stabilized soils than the OPC‐solidified/stabilized soils. The GFA‐solidified/stabilized soil displayed considerably lower leachability, bioaccessibility, and phytoavailability of Pb and higher mechanical properties and chemical stability than the OPC counterpart. This study demonstrated that GFA had a better effect than OPC on the solidification/stabilization of Pb‐contaminated soils.