82 / 2022-04-15 16:11:20

Experimental study on mechanical properties of seawater sea-sand concrete with sea-sands from different regions

sea sand,concrete,mechanical property,pore structure

This study selected the undisturbed sea sands from Shandong Province, Fujian Province and Guangxi Province as the research objects, and studied the influence mechanism of the sea sands from different regions on the mechanical properties of concrete. The physical and chemical properties of the sea sands were first characterized with the optical microscope, element titration, XRD and SEM. And the results were further compared to those of the river sand from Changsha. It is indicated that the mineral composition, fineness modulus and crushing value of sea sands are consistent with those of river sand. Meanwhile, the sea sands from different regions possess different chloride and shell contents. Then the seawater sea-sand concretes (SWSSCs) with three different strength grades (C30, C40 and C50) were prepared with the sea sands from different regions and the artificial seawater. The mechanical tests were conducted to examine the cubic and axial compressive strengths, static elastic modulus and splitting tensile strength of the prepared SWSSC. Then the evolution mechanism was examined with the combined XRD and SEM study. And the results were also compared with those of the OC. The results showed that the early-age (3 d and 7 d curing age) compressive strength of the SWSSC was higher than these of the ordinary concrete (OC), while its late-age (After 28 d curing age) compressive strength is lower than that of OC. The tensile strength gap between SWSSC and OC gradually decreased with the curing age, and the long-term (360 d curing age) tensile strength of SWSSC was still higher than that of OC. Finally, the pore structures of SWSSC and OC at different ages were compared through the low field ¹H NMR test. It was found that the pore structure development of SWSSC and OC were consistent with their strength development. This study can provide a solid basis for the mix design and engineering application of SWSSC.