Properties of lightweight foamed concrete containing gold tailings as subgrade filler

Gold tailings is formed as an industrial waste during gold mining and processing. The aim of the current study is to use it to prepare foamed concrete as subgrade filler. The effect of wet density (600, 700 and 800 kg/m3) and tailings content (15, 30, 45 and 60 wt%) on fluidity, compressive strength, elastic modulus, drying shrinkage, freeze-thaw resistance, hydration heat and pore structure were investigated. It was found that incorporating tailings into foamed concrete decreases the compressive strength as tailings adversely affected the pore structure, resulting in increased porosity, enlarged and connected pores, and reduced sphericity. To meet the requirement of subgrade filler, the tailings content was limited to 30 wt% when the designed wet density was 600 kg/m3 and it was 45 wt% when the wet density increased to 700 and 800 kg/m3. Nevertheless, increasing the tailings content effectively reduced the drying shrinkage and early age hydration heat which are favorable for massive foamed concrete construction. Besides, the incorporation of gold tailings is helpful to the freeze-thaw resistance of 600 and 700 kg/m3 foamed concrete for application in seasonal frozen areas.