Basalt FRP-confined slag-based alkali-activated seawater coral aggregate concrete: Concept and axial stress-strain behavior

This paper presented an experimental investigation on the axial stress-strain behavior of cement-based seawater coral aggregate concrete (CAC) and slag-based alkali-activated seawater coral aggregate concrete (AACAC) confined by basalt fiber-reinforced polymer (BFRP) sheet, with different BFRP confinement stiffnesses (i.e., 0, 1, 2, 4, and 6 plies) being considered. The experimental results indicated that the FRP confinement was an effective method in enhancing the loading capacity and deformation of cylinder specimens. As the FRP jacket confinement (layer) increased, the slope of the axial stress-strain curves at the ascending branch, axial compressive strength (fcc), and ultimate axial strain (epsilon cc) corresponding to fcc of BFRP-confined CAC and AACAC were gradually enhanced. Compared with the un-confined specimens, the axial compressive strength and ultimate axial strain of the CAC specimens with 6-layer FRP confinement increased by 1.94 and 12.35 times, respectively, while those of the AACAC specimens increased by 2.40 and 10.94 times, respectively. Finally, the expressions for the ultimate strength and ultimate strain of BFRP-confined CAC and AACAC were proposed, and were compared with tested results of FRP-confined CAC available in the literature to verify the reliability of the proposed models.