Effect of aluminate content in cement on the long-term sulfate resistance of cement stabilized sand |
| |
Authors: | Kaiwei Liu Yueming Wang Aiguo Wang Daosheng Sun Xingxing Chen |
| |
Affiliation: | 1. Anhui Key Laboratory of Advanced Building Materials, Anhui Jianzhu University, Hefei, China;2. Department of Civil and Environmental Engineering, University of Hawaii at Manoa, Honolulu, HI, USA |
| |
Abstract: | AbstractDurability of cement-based materials for marine/coastal structures is an increasingly challenging problem. Sulfate ions in seawater can react with aluminate in cement to form erosion products, causing cracks and spalling. When cement is used to stabilize loose erodible sand in coastal areas, the resistance to sulfate attack is questionable. In this study, four cements with different aluminate contents were used to stabilize sand. Cement stabilized sands were immersed in 5% Na2SO4 solution for 300-days to simulate long-term sulfate attack process. The deterioration of engineering performance was evaluated based on expansion ratio, mass change, uniaxial compressive strength, and ultrasonic velocity. The deterioration mechanisms were analyzed through mineralogical and microstructural observations including X-ray diffraction, EDS, scanning electronic microscopy, and nuclear magnetic resonance. The results showed that the development of macro-scale mechanical performances could be divided into two stages (initial stage and erosion stage) when subjected to 300-days immersion in 5% Na2SO4 solution. Sand stabilized by low-aluminate-content cement displayed better engineering performance especially at the erosion stage. Mechanistically, more ettringite was formed in high-aluminate-content cement stabilized sand, leading to swelling and cracking. The formation of ettringite and gypsum were accompanied with the consumption of portlandite, leading to further strength loss. |
| |
Keywords: | Coastal erosion stabilized sand Portland cement sulfate attack aluminate |
|
|