Mechanical and microstructure characteristics development of hardened oil well cement pastes incorporating fly ash and silica fume at elevated temperatures

Abstract

The performance of oil well cement (OWC) incorporating pozzolana under diverse hydrothermal curing circumstances was inspected. OWC was partially replaced by 5 weight% of silica fume (SF) or fly ash (FA). The prepared composites were cured under different hydrothermal circumstances (60°C/0.02 MPa, 100°C/0.1 MPa and 150°C/0.48 MPa) for 7 days. The outcomes established that increasing curing temperature and pressure brought about a decline in the compressive strength magnitudes of various neat OWC pastes. This finding is correlated to the metamorphosis of CSH to the greatly crystalline phase of α-dicalcium silicate hydrate (α-C2SH). Such transformation motivates the destruction of the pore structure and promotes compressive strength decline. Admixing OWC with 5 wt.% SF or FA displayed enrichment in the mechanical aspects accompanied by the progression of highly compact microstructures. Additionally, the presence of SF or FA motivates the advancement of stable and desirable hydration products. DTG/TG, XRD and SEM analyses affirm these results.