BONDING BEHAVOR OF REINFORCEMENT IN ALKALI-ACTIVATED SLAG-FLY ASH MORTAR

Both the Portland cement (PC) and the no-cement alkali activated slag-fly ash material (AAM) were used as the cementitious binders to cast 150x 150x 150 mm(3) cubic mortar specimen for pull-out bonding test of reinforcement with two different diameters of reinforcement (phi = 13 mm and 16 mm) and two different embedment lengths (75 mm, 150 mm). The research results show, at the same w/cm of 0.45, that the alkali activated slag-fly ash mortar with 3 % activator had the compressive strength of 31.82 MPa and the bonding strength of 8.69 MPa, which were lower than those of 39.59 MPa and 12.38 MPa for Portland cement mortar by 19.6% and 29.8%, respectively. When the embedded length of reinforcement is 75 mm, all the specimens fail in pullout type, but when the embedded length becomes 150 mm, the mode of failure is decided by diameter of reinforcement. Both the PC and AAM mortars show the similar values of normalized bonding stress ratio between 0.2 and 0.3.