Effect of replacing freshwater river-sand with seawater sea-sand on dynamic compressive mechanical properties of concrete

The substantial increase in infrastructure construction has led to a scarcity of river sand and freshwater resources in most countries. To address this issue, the replacement of freshwater river-sand with abundant seawater sea-sand in concrete is considered a sustainable construction method. To this end, this paper investigates the effect of replacing freshwater river-sand with seawater sea-sand on the dynamic compressive mechanical properties of concrete. First, compressive tests were conducted on both types of concrete at different strain rates using static compression testing machine and large-diameter splitting Hopkinson pressure bar. Then, the effects of strain rate on the stress-strain curve, peak stress and strain, dynamic increase factor (DIF) of compressive strength, ductility coefficient, and energy absorption density for both types of concrete were analyzed. The static and dynamic failure modes of specimens were obtained. The experimental results showed that the replacement of freshwater river-sand with seawater sea-sand had no substantial effect on the static and dynamic failure modes of concrete. Furthermore, this replacement did not change the basic shape of the stress-strain curve of concrete. At high strain rate, the DIF for the compressive strength of seawater sea-sand concrete (SSMC30) exceeded that of freshwater river-sand concrete (NC30). The ductility coefficient and peak strain of SSMC30 were both smaller than those of NC30 at the same strain rate. The energy absorption density of SSMC30 was lower than that of NC30 under the same strain rate. Following experimental investigation, a unified stress-strain constitutive relation model of SSMC30 under static and dynamic compression was established using numerical regression. The model is useful for evaluating the dynamic response of SSMC30 structures.