Development of synthetic aggregate using off-ASTM specification ashes: Fid-Bau Portal

Development of synthetic aggregate using off-ASTM specification ashes

Shon, Chang-Seon / Jung, Youn Su / Saylak, Don / Mishra, Surendra K.

Highlights ► Synthetic aggregates were produced using off-ASTM specification ashes. ► The optimum water/FBC fly ash for the highest strength was determined to be 0.5. ► The 100% RH and 40°C were determined to be the optimum curing conditions. ► Both FBC ash and stockpiled ash can be used to manufacture light weight aggregates.

Abstract This paper presents a comprehensive laboratory evaluation for developing synthetic aggregate using off-ASTM specification ash produced through a fluidized bed combustion (FBC) process. To determine optimum mix design which produces strong and durable synthetic aggregate, different combinations of water to fly ash ratio, various combination of fly ash (FAf) to stockpiled material (FAsp) ratio, curing temperature, and calcium chloride content were applied. Then, to evaluate the performance of synthetic aggregate for construction application, basic characteristics of synthetic aggregate such as density, specific gravity, absorption, gradation, strength, abrasion resistance, and soundness were carried out. The results indicate that 100% RH and 40°C was determined to be the optimum curing conditions for both fly ash paste and FAf/FAsp mortar mixtures in terms of strength and minimal potential sulfate attack. The aggregate characterization results indicate that the produced synthetic aggregates met ASTM C 33/330 criteria for a concrete aggregate without inducing any soundness problems despite their relatively high water absorption. Therefore, the FBC ash and stockpiled ash can be used as primary resource materials for manufacturing synthetic light weight aggregate.