贝壳粉对碱激发海水海砂混凝土力学性能和微观结构的影响OA

Shell powder(SP)was used to partially replace fly ash(FA)in the preparation of alkali-activated seawater sea-sand concrete(AASSC).The effects of SP content(0-60%)and sodium hydroxide solution(SH)concentration(8-12 mol/L)on the workability,mechanical properties,and microstructure of AASSC were systematically investigated.The results indicate that SP can effectively serve as a cementitious material in place of FA.At an optimum content of 15%,SP increased the 28-day cube compressive strength of AASSC to 60.63 MPa—approximately 20%higher than the SP-free group—and increased the splitting tensile strength by about 30%.SEM analysis revealed that the 15%SP content reduced voids resulting in a denser microstructure.However,the incorporation of SP reduced the slump and shortened the setting time,impairing workability.Furthermore,a high SH concentration(12 mol/L)significantly enhanced the early strength of AASSC,increasing the 3-day compressive strength to 26.12 MPa,but partially inhibited the sustained growth rate of later strength.