Experimental Study On Preparation Of Coal Ash Lightweight Aggregate And Its Roadbed Strength Tests

Using coal ash,lime and cement as raw material,mixed with chemical additive, through burden, pelletization and curing process, the new type of environmental friendly energy-saving and green building material—non-sintered coal ash lightweight aggregate could be prepared. Machenical tests were carried out to investigate the effects of material compositon, activator and additive category, coal ash size and curing on coal ash lightweight aggregate. XRD and ESEM were useded to analyze the hydrating reaction machenism.The experiments on substituting the aggregate for crushed stone as roadbed materials were performed with coal ash, cement and lime as cementation material, desulfuration gypsum as early-strength agent. was performed. The roadbed strength testing results showed that 7 day' compress strength of roadbed achieved 3 MPa and 28 day' one achieved 5 MPa when content of cement is 5% and desulfuration gypsum was 1.25%. The dry density 1.34g/cm~3 was 80% lower than the one of crushed stone roadbed so that cement consumption was cut down. Using coal ash, lime and desulfurization gypsum as cemented material, the 7 day' compress strength was easy to reach 1 MPa, and 3 Mpa for 28 day'. The desulfurization gypsum, a kind of solid waste for coal-fired power station, was added to increase the early strength of roadbed, in the meantime pavment cost was lowed. It is believed that the non-sintered coal ash lightweight aggregate with high strength, low density, high coal ash content will be applied to actual roadbed construction in the near future.