Effects of re-curing on microstructure of concrete after high temperature exposure

• Published in: Construction & building materials Vol. 168; pp. 431 - 441
• Main Authors: Akca, Abdullah Huzeyfe, Özyurt, Nilüfer
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.04.2018; Elsevier B.V
• Subjects: Calcium silicate; Chemical properties; Concretes; Deterioration; Fiber reinforced concrete; High temperature; Microstructure; Recovery; Structure; Turkey; High temperature; Microstructure; Deterioration; Recovery; Fiber reinforced concrete
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2018.02.122

•High temperature exposure and re-curing cause morphological changes in concrete.•Hydrates disappeared after heating, resulting in a decrease in mechanical properties.•Rehydration of CaO caused further deterioration of concrete after air re-curing.•Regeneration of hydrates resulted in mechanical recovery in water re-cured concrete. Concrete contains many phases such as ettringite, portlandite, C-S-H etc. which undergo phase changes by forming some active products such as lime and calcium silicates during heating. These new active phases give reactions with water and carbon dioxide in air and affect the residual properties of concrete after subsequent days of cooling. In order to understand better these phase changes and their effects on residual properties, 3 different types of concrete were produced depending on mineral admixture type. Concrete specimens were heated to 1000 °C and one face heating procedure was applied in the furnace. Then concrete specimens were subjected to air and water re-curing processes. Microstructural investigations XRD, TGA and SEM/EDX were conducted on the samples obtained from concrete specimens.