Sulphate attack is a serious problem for concrete in marine environments. Sulphate attack can change the composition and microstructure of concrete and eventually influence the mechanical and durability performance. In this paper, the heterogeneity and mechanical properties of concrete exposed to sulphate is investigated from the microscopic to the mesoscopic scale. X‐ray computed tomography (XCT) and nano‐indentation were adopted to define the defect zone and establish the relationship between interfacial transition zone (ITZ) and concrete matrix (mortar). The experiments were based on concrete and mortar specimens of different strengths. The results of XCT have nano‐indentation indicate that the specimens had similar degrees of damage regionally and good correlation exists between the elastic moduli of the ITZ and the mortar. The concrete can be partitioned into three parts: the cracked zone with heavy damage, damaged zone and undamaged zone. The elastic modulus of the mortar phase and the ITZ has a linear relation.

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The disturbed state concept (DSC) provides a general way for constitutive modeling of deforming materials. This paper presents the experimental and analytical results for the development of methodology for predicting the stress-strain response of concrete attacked by sulfate. Ultrasonic pulse velocity (UPV) is used to identify a function for disturbance (D). The elastoplastic model and simplified hydrostatic stress model are adopted for the definition of the relative intact state (RI) and fully adjusted state (FA), respectively. Thus, the stress–strain curve can be predicted using the DSC model based on nondestructive method. The comparison results show that the proposed constitutive model is satisfied with application in similar condition.