Durability of autoclaved construction materials of sewage sludge-cement-fly ash-furnace slag

Various mechanical properties such as flexural strength, compressive strength and the toxicity characteristic leaching procedure (TCLP) were evaluated. To evaluate long-term performance, different types of accelerated attacks, i.e. freezing-thawing cycles, accelerated carbonation, wet-dry cycles, and heat-cool cycles were also determined. The obtained test results were indicated that the autoclaved samples exhibit good long-term performance after evaluations of different durability tests. XRD patterns show that the hydration products of autoclaved samples are katoite and C-S-H phases, which mainly contribute to strength of autoclaved products. Morphologies of autoclaved samples also demonstrate the existence of the gel-like and honeycomb-like hydrated products. The results show that this new construction material could be applied as many construction and building materials, i.e. landfill liners and building blocks.