Thermal and mechanical properties of alkali-activated slag paste, mortar and concrete utilising seawater and sea sand

• Published in: Construction & building materials Vol. 159; pp. 704 - 724
• Main Authors: Li, Ying-Lei, Zhao, Xiao-Ling, Singh Raman, R.K., Al-Saadi, Saad
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.01.2018; Elsevier B.V
• Subjects: Alkali-activated concrete; Building materials; Elevated temperature; Mechanical properties; Properties; Reinforced plastics; Sands; Seawater and sea sand concrete (SWSSC); Slag cement; Thermal properties; Thermal properties; Alkali-activated concrete; Elevated temperature; Seawater and sea sand concrete (SWSSC)
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2017.10.104

•Tests on seawater and sea sand concrete (SWSSC) under elevated temperatures.•Temperature gradient, mass loss and thermal strain of SWSSC were measured.•Mechanical properties of SWSSC at elevated temperatures were measured.•X-ray CT scanning and SEM were used to explain failure mechanism of SWSSC. This paper presents an experimental study on the thermal properties of alkali-activated slag paste, mortar and concrete utilising seawater and sea sand exposed to elevated temperature. The thermal properties of paste and concrete utilising cement, fresh water and river sand were also investigated for comparison purpose. The samples were heated to different target temperatures up to 1000 °C at a heating rate of 5 °C/min, and tested both under hot and cooled conditions. The thermal properties, including temperature gradient, visual observation, mass loss, thermal strain and mechanical properties (i.e. strength, Young’s modulus and stress-strain curve) were investigated. X-ray CT scanning and scanning electron microscopy (SEM) were conducted to understand the macro/microscopic changes of the paste and concrete in response to heating. Degradation in mechanical properties of slag paste is attributed mainly to the cracks induced by temperature gradient, pore pressure and phase change. The degradation of concrete is caused by thermal mismatch between paste matrix and aggregates regardless of the use of cement or slag, freshwater or seawater, and river sand or sea sand.