Early age properties of alkali-activated cement and class G cement under different saturation conditions in oil well applications. (15th February 2021)

• Record Type: Journal Article
• Authors: Samarakoon, M.H.; Ranjith, P.G.; Hui Duan, Wen; Chen, Bernard K.; Khandelwal, Manoj
• Is Part Of: Construction & building materials. Volume 271(2021)
• Publication Date: 2021-02-15
• Subjects: Alkali-activated cement -- Class G cement -- Oil well cementing -- Rheology -- Strength -- Microstructure; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2020.121543
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Alkali-activated cement (AAC) and Class G cement (GC) were characterized under water, brine and CO2 . Rheological properties of AAC were improved at 60 ℃ than ambient temperature. AAC showed higher early strengths under brine but lower strengths under CO2 compared to GC. Salt crystals precipitation and Portlandite leaching altered the microstructure of brine cured GC. AAC showed a higher fraction of mesopores with poorly crystalline CaCO3 under CO2 conditions. Abstract: This experimental study evaluates the early-age properties of one-part alkali-activated cement (AAC) and class G cement (GC) under three subsurface curing conditions of water, brine, and carbon dioxide (CO2 )-saturated water. The novel one-part AAC used in this study consist of fly ash and slag as the mineral precursors activated by a waste glass/sodium hydroxide-based solid alkali activator. The fresh and hardened properties of AAC and GC were characterised using rheology, strength, and microstructural tests. AAC showed relatively lower flow and setting time than GC under ambient conditions. Both the yield stress and plastic viscosity of AAC were reduced at elevated temperatures. AAC showed comparable strengths under water, higher strengths under brine, and lower strengths under CO2 saturation conditions compared to GC. Microstructural tests of GC evidenced the precipitation of chloride salt and leaching of Portlandite under brine conditions. A higher total porosity of AAC was reported with poorly crystalline calcium carbonate deposits under CO2 saturation. The early strength of one-part AAC should be improved by using suitable additives before their use for oil well-cementing, especially in CO2 -rich conditions.