Dynamic Properties of High Volume Fly Ash Nanosilica (HVFANS) Concrete Subjected to Combined Effect of High Strain Rate and Temperature

The study aims to determine the dynamic properties of high volume fly ash nanosilica (HVFANS) concrete exposed to strain rates between 30.12 to 101.42 s(-1) and temperatures of 25, 400, and 700 degrees C by using split Hopkinson pressure bar (SHPB) machine. The static and dynamic compressive strengths of HVFANS concrete were slightly lower than plain concrete (PC) at room temperature, while its values were higher at 400 and 700 degrees C. The results proved that the CEB model of dynamic increase factor is more reliable to estimate the behaviour of HVFANS concrete at studied temperatures. The toughness, critical strain, and damage of HVFANS concrete recorded a superior performance than PC under studied strain rates and temperatures that would reflect the possibility of use HVFANS concrete in structures to improve its resistant of fire and impact loads, as well as to decrease the demand on Portland cement which could lead to restrict the risks of liberated gases during cement production. Furthermore, equations were proposed to estimate the dynamic increase factor, toughness, and critical strain of both concretes under investigated conditions.