Mechanical properties and durability of unconfined and confined geopolymer concrete with fiber reinforced polymers exposed to sulfuric acid

This study reports the mechanical properties and durability of unconfined/confined sustainable geopolymer concrete (GPC) exposed to sulfuric acid attack under static and cyclic loadings. A low calcium (Class F) fly ash incorporating nano-silica was activated by a combination of sodium silicate and sodium hydroxide solutions to make the GPC. Unconfined/confined ordinary Portland cement concrete (OPCC) counterparts were also made for comparison purposes. The confined GPC/OPCC specimens were wrapped by one/three layers of basalt/carbon fiber-reinforced polymers (BFRP/CFRP). Effects of type and number of wrapping layers, along with wrapping and testing ages on the mechanical properties and durability of confined GPC/OPCC were investigated. In addition, microstructure of the unconfined/confined GPC specimens was compared with that of the unconfined OPCC counterparts. The results showed confinement of the GPC with BFRP/CFRP fabrics enhanced the strength, ductility and durability of the GPC exposed to sulfuric acid. The GPC confined with CFRP fabric was more ductile and durable than that confined with BFRP fabric. In addition, the GPC confined with three layers of BFRP/CFRP fabric was more ductile and durable than that confined with only one layer. Further, the unconfined/confined GPC was more durable than the corresponding unconfined/confined OPCC. (C) 2019 Elsevier Ltd. All rights reserved.