In order to study the impact of different types of additives on the interfacial transition zone(ITZ)of the geopolymer interface,this study employs a variable angle shear test to study the impact of the interface mechanical behavior of geopolymer materials.The Mohr-Coulomb criterion is used to char-acterize the friction angle and bonding strength within the interface.The microstructure of the fracture surface is analyzed by scanning electron microscopy and energy spectroscopy(SEM-EDS).The research results show that the internal friction angle at the interface between geopolymer and rock ranges between 38° and 48°.In the same set of control experiments,the internal friction angle at the interface is nega-tively correlated with the cohesion force.For the same type of rock,higher strength shows higher interfa-cial bonding strength.The three fiber materials have a positive impact on the bonding strength of the slag-geopolymer material and aggregate,among which the glass fiber reinforcement effect is the most significant,at 3.72 MPa.Among all test results,silica fume has the greatest enhancement effect on in-terfacial cohesion,which is 3.79 MPa.ITZ is the weakest zone in slag-geopolymer concrete.SEM-EDS test results show that the surface geopolymer-rock interface transition zone mainly exists in geopolymer materials,with the width of the interface transition zone between 10 and 20 μm.
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