Authors: Erika Yukari Nakanishi, Matheus Roberto Cabral, At?lio Luiz Gasparini Pasqualinotto , Joahnn Palacios, St?phane Godbout, Holmer Savastano J?nior
Published in: CSBE-SCGAB Technical Conferences » 5th CIGR and AGM Quebec City 2021 » 9th Concrete for sustainable agriculture International Symposium
This study evaluated the effect of two cooling conditions on the pozzolanic activity of elephant grass ash (EGA) in blended cement matrices. The elephant grass ash was burned at 400?C and treated using hydrochloric acid, and subsequently, it was re-burned at 700?C for 1 h. Thereafter, two cooling processes were adopted: (1) slow cooling - SC: after burning, the EGA was kept inside the furnace for natural cooling. (2) fast cooling - FC: after burning, the EGA was taken out of the furnace to force the cooling process, through which, EGA reached 100?C in 60 min. By the pozzolanic activity test, it was found a higher pozzolanic activity for EGA-FC in comparison to EGA-SC. Cylindrical specimens with 20% of Portland cement (PC) replaced by ashes were tested with 28, 60 and 90-day age. The ash replacement differed for the mechanical property for both the treatments when compared to the control (PC control) (p>0.05). Mechanical values do not show difference between the SC and FC ashes. The PC-EGA-FC and PC-EGA-SC at 28 and 60 days presented higher physical properties of dry bulk density and lower water absorption and apparent void volume than PC control (p>0.05). At the 90-day age, the FC modified the properties of the ashes resulting in differences in the physical properties. Therefore, the replacement of the ashes furthered better mechanical and physical properties. However, there was no difference between both the cooling process in the mechanical and physical properties at 28 and 60-day age in blended cement matrices.