Mechanical properties and durability of lightweight cenosphere cementitious composites under coupling effect of dry-wet cycles and salt erosion

Cenospheres are suitable as supplementary cementitious materials to partially replace cement in the production of environmentally friendly lightweight cenosphere cementitious composites (LCCC). In this study, the correlation between the content and particle size of the cenosphere, the early curing system and the performance of LCCC was analyzed. The macroscopic properties and microstructural changes of LCCC under the conditions of dry-wet cycles and salt erosion were studied with different early curing conditions. The durability changes of LCCC mortar under the coupling effect of salt erosion and dry-wet cycles were studied by examining the mass loss rate, relative dynamic modulus of elasticity and salt corrosion resistance coefficient of LCCC mortar. Finally, a comparative analysis of the impact of existing cracks on the performance of LCCC under the coupling effect of dry-wet and salt erosion was conducted. The main innovation of the study includes the mechanical properties and durability of LCCC under dry-wet-salt erosion conditions, as well as the clarification of the impact of prefabricated cracks on the mechanical properties and durability of LCCC. It is found that the flexural strength and the compressive strength of specimens cured at high temperature is generally lower than that of the specimens cured under normal temperature conditions. The wet-dry salt corrosion can exacerbate the erosion the outer shell and inner wall of cenospheres and disrupt the stability of the internal interface transition zone (ITZ) in LCCC. LCCC with CsS exhibits better macroscopic performance and microstructural properties. Pre-existing cracks accelerates the erosion in the cenosphere shell and inner wall under salt solution.