Study On Characteristics And Deterioration Law Of Interfacial Transition Zone Of Geopolymer Concrete

The interfacial transition zone of geopolymeric concrete is the weak link of geopolymer concrete,which determines the mechanical properties and durability of geopolymer concrete.The study of the mechanical properties and deterioration of the transition zone of geopolymer concrete helps to improve the mechanical properties and durability of concrete.In this paper,the geopolymeric concrete test block formed by waste(slag powder,fly ash),water glass,strong alkali(NaOH)and aggregate(granite,marble),which is used to study the mechanical properties,deterioration mechanism and micro-morphology of the interface transition zone.The test is based on the ratio of slag powder/fly ash(4:6,5:5,6:4,7:3),water-solid ratio(0.29,0.32,0.35,0.38),water glass modulus adjustment(1.8,1.5,1.2,0.9),alkali content ratio(5%,7%,9%,11%),aggregate(granite,marble)as a variable to prepare geopolymeric concrete.The variation of the flexural strength of 3d,7d,14 d and 28 d in the interfacial transition zone of geopolymers under different variables was studied experimentally.Study on the deterioration of interfacial transition zone of geopolymer concrete with a mixture ratio in dry-wet cycle test(tap water and seawater medium)and freeze-thaw cycle test.Scanning electron microscopy and energy spectrum analyzer were used to observe the microscopic morphology and element distribution of geopolymer interface transition under different ratios,and the relationship between bond strength and microscopic properties in the transition zone of geopolymer concrete interface is discussed.The results show:(1)With the increase of the ratio of slag powder/fly ash,watersolid ratio,water glass modulus and alkali content,the bond strength of geopolymer and interface transition zone first increases and then decreases;(2)When the aggregate is marble,the bond strength of the interface transition zone is higher than the bond strength of the aggregate;(3)Geopolymers subjected to dry-wet cycle t(tap water and seawater media)and freeze-thaw cycle test,as the number of cycles increases,the quality and interface strength decrease continuously,and the mass loss rate and strength loss rate become larger.Among them,the geopolymer has better resistance to sea-water attack.(4)Scanning electron microscopy and energy spectrum analysis revealed that the elemental distribution in the geopolymer concrete interface was uneven.