Slag-based engineered geopolymer composite undergoing freezing and thawing action: Mechanical behavior evolution

Inheriting the advantages of high ductility of engineered cementitious composite and low carbon of geopolymer, engineered geopolymer composite (EGC) has attracted increasing attention. To enhance the understanding of the frost resistance of EGC, this study comprehensively investigated the mechanical properties from the aspects of the uniaxial tensile properties, compressive strength, flexural strength, and dynamic elasticity modulus after undergoing different freezing and thawing (FT) actions. The mechanism of the tensile behaviors was explained by the combination of the matrix and the fiber bridging properties. Scanning electron microscopy (SEM) technique was executed to further reveal the variation of the mechanical properties. The results indicated that the FT action compromised the mechanical properties. The tensile strength and tensile strain can remain at a desirable level at 200 FT cycles. The compressive strength still reached 60 MPa after 300 FT cycles. The decrease rates of the flexural strength and dynamic elasticity modulus were at a similar level of around 35 % after 300 FT cycles. The increased pores in the matrix resulted in a decrease in matrix toughness and compressive strength. The weaker interfacial bonding between fiber-matrix decided the decreased fiber bridging effect, leading to the decrease in the tensile properties. The current findings can provide some essential references for the application of EGC in the cold areas.