Effect of temperature on the strength of lime-stabilised fly ash

Abstract

Class F fly ash cannot be used alone as a construction material due to its low self-cementing properties. This paper reports the compaction characteristics, strength properties and microstructure of lime-amended fly ash with varying lime content from 0 to 12%. The effects of the curing temperature on the strength and microstructure of the lime-amended fly ash are studied at different curing periods varying from 0 to 60 d and with the curing temperature varying from 10 to 90°C. The test results showed that an increase in either lime content, curing period or temperature increases the unconfined compressive strength (U CS) and California bearing ratio (C BR) values. It also influences the formation type and amount of hydration products. Lower-temperature-cured specimens show a continuous improvement in strength with curing age, whereas the strength of high-temperature-cured specimens stabilises much earlier. The mineralogical study established crystalline phases of calcium aluminium silicate and aluminosilicate with the presence of ettringite, which imparts higher strength.