Seismic performance of ternary composite geopolymer recycled concrete columns: Experimental study and modeling

In order to achieve seismic -resistant structures cast from green building materials, a new kind of column, ternary composite geopolymer concrete with recycled aggregates containing recycled fireclay brick aggregates (GRA-RFBAC) column, was proposed in this paper. The ternary binder material in GRA-RFBAC was produced by the combination of industrial by-products (ground granulated blast furnace slag (GGBS), recycled fireclay brick powder (RFBP), and fly ash (FA)) and alkali -activated solution. Cyclic loading tests of five reinforced GRA-RFBAC columns, each with a shear -to -span ratio of 3.07, were conducted to investigate the seismic performance. The influence of the recycled aggregate containing recycled fireclay brick aggregate (RA-RFBA) replacement ratio, stirrup spacing, and axial compression ratio on the seismic performance of GRA-RFBAC columns was discussed. The results indicated that all specimens showed similar flexural failure modes under cyclic loading. The first cracking of concrete occurred within the drift ratio range of 0.18%-0.41%, the failure drift ratio varied from 3.27% to 4.11%, and the peak load of the specimens ranged from 237.50 kN to 288.87 kN. Although increasing the RA-RFBA replacement ratio led to a decrease in both the bearing capacity and lateral stiffness of the columns, the GRA-RFBAC columns showed comparable or even better seismic performance than Portland cement concrete columns. Moreover, a prediction model for the skeleton curve of GRARFBAC columns was proposed and verified by comparing the prediction results with the test results.