Effect of Modified Carbon Nanotube on Mechanical Property of Set Cement

Abstract Two modified carbon nanotubes, TNIMH4(—OH) and TNIMC6(—COOH) were selected to satisfy the needs of natural gas storage and high pressure oil and gas well for better mechanical performance of set cement. Laboratory experiments showed that cement slurry treated with 0.01% TNIMH4 had its compressive strength increased by 4.32%, cement slurry with 0.07% TNIMC6 had its compressive strength increased by 19.18%. At the same treatment, the compressive strength of cement slurry treated with TNIMC6 was greater than that of cement slurry treated with TNIMH4. Tri-axial compressive strength experiments showed that the tri-axial compressive strength of the cement slurry treated with TNIMC6 was 41.21% greater than that of the blank cement slurry., and the elastic modulus of the cement slurry was increased from 3,692.5 MPa to 4,366.5 MPa. SEM observation showed that the nanotubes at low concentrations were dispersed evenly in the set cement, and began to agglomerate at increasing concentrations, which in turn aggravated the heterogeneity of, and hence weakened the strength of the set cement.