Dependences of dynamic compressive and tensile strengths of four alkali-activated mortars on the loading rate and curing time

摘要

There is recently an increasing interest in replacing ordinary Portland cement (OPC) with a sustainable binder used in construction materials because of heavy energy consumption and greenhouse gas emissions in OPC production. Alkali-activated binder made from industrial waste is therefore developed as an alternative to OPC. It is essential to assess the mechanical properties of construction materials using the new binders. Since materials behave differently when subjected to dynamic loading as compared to its response under static loading conditions, this paper aims to evaluate the mechanical properties of alkali-activated binder based mortars subjected to dynamic loading. Mortars containing low-calcium (fly-ash) and high-calcium (ground granulated blast-furnace slag) alkali-activated binders were tested. NaOH and sodium silicate solutions were used together as activators, and two groups of specimens made with different water ratios were tested for both fly-ash and blast furnace slag based mortars. The split Hopkinson pressure bar (SHPB) system was used to conduct dynamic tests, and dynamic compressive strength and tensile strength were measured to provide a comprehensive understanding of the dynamic behaviors of alkali-activated mortars. The results show that dynamic compressive and tensile strengths of alkali-activated mortars increase with the loading rates. In addition, water ratio and curing time significantly affect the dynamic compressive and tensile strengths of alkali-activated mortars. Finally, empirical formulas were established to describe dynamic behaviors for fly-ash and slag based mortars with different water ratios and curing time. (C) 2019 Elsevier Ltd. All rights reserved.