Dynamic mechanical properties of geopolymer concrete after water immersion

This paper aims to investigate the influence of water immersion on dynamic mechanical properties of geopolymer concrete (GC). Dynamic compressive tests on specimens placed indoors (GC(N)) and specimens with water immersion (GC(W)) were conducted by a split Hopkinson pressure bar system. The results indicate that the dynamic strength and impact toughness of GC(N) and GC(W) display an increasing trend as strain rate increases, while the elastic modulus is not rate-sensitive since no obvious trends can be observed with strain rate. The quasi-static strength of GC decreases after water immersion. Under impact loading, however, water immersion exhibits a strengthening and stiffening effect on GC as confirmed by the higher dynamic strength and higher dynamic elastic modulus of GC(W). And the absorbed water within specimen also improves the rate sensitivity of GC's strength performance. Besides, water immersion has a minor influence on the impact toughness of GC. However, as compared with GC(N), GC(W) dissipate less impact energy prior to the peak load and have a lower average deformation during the impact procedure. In general, the impact damage of GC(W) is less serious than that of GC(N) at approximately the same strain rate. The fragment size of GC(W) distributes in the coarser grained side. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.