Behavior of steel tubed rubberized geopolymer concrete columns under axial compression: Experimental study and analytical modeling

Abstract

Rubberized geopolymer concrete (RuG) has become increasingly popular due to its capability of sustainable utilization of resources, but the mechanical properties of RuG could deteriorate significantly with the increase of rubber content. To mitigate the adverse effects of rubber and further promote the engineering applications of eco-friendly building materials, a new type of composite column, i.e., steel tubed rubberized geopolymer concrete (ST-RuG) columns, was proposed and tested in this paper. The influence of concrete types, rubber replacement ratios, the configurations of steel tubes, and diameter-to-thickness ratios on the compressive behavior of specimens was analyzed. The test results show that the incorporation of rubber has a deterioration effect on the strength of ST-RuG columns with a maximum degradation of 37.6%, but it can improve the ductility of specimens to a certain extent, which is slightly superior to steel tubed rubberized ordinary concrete (ST-RuO) columns. Due to the inherent brittleness of geopolymer concrete (GPC), more obvious residual behavior is detected for ST-RuG compared with ST-RuO under the same rubber replacement ratio Rf. Moreover, with the increase of Rf, the confining pressure of ST-RuG specimens gradually decreases, and a significant decreasing trend is observed for both the peak stress ratio and residual strength ratio of confined RuG. Finally, a new stress-strain model considering the effect of rubber replacement ratio is developed, and comparisons with test results reveal that the proposed model possesses satisfactory accuracy in predicting the axial stress-strain curves of steel-confined GPC and RuG.