For a low spec application like a sidewalk or maybe a "compression only" footer you could mix in more fly ash. For things that need to be strong, like bridge beams and building columns you can only use pure hydraulic cement of the proper specification.
64.233.179.104
TECHNOLOGY ASSESSMENT FOR SUPERCEMENT FOR ANNULAR SEAL AND LONG-TERM INTEGRITY IN DEEP- HOT WELLS
I read about this SUPERCEMENT - they are going to replace portland cement - it is not a question of IF - only WHEN.
netl.doe.gov
Background:
While additives in current cement compositions and well designed placement techniques can enhance zonal isolation in high-temperature, high-pressure (HTHP) wells, industry experts continue to report a high incidence of failure in deep, hot wells, presumably due to inadequate placement and mechanical failure of cements. Even when cement is placed properly, temperature and pressure gradients encountered through production can induce very high stresses in the wellbore, exceeding the resistance capabilities of conventional Portland cement systems. Short-term and long-term fluid migration of water and/or gas can also affect the sealing properties of Portland cement, and mechanical cement failure is exaggerated in wells with narrow annuli because of the stress imposed by temperature, pressure cycling and corrosive gases such as CO2 and H2S.
The supercement will possess superior pipe and formation-bonding capabilities to ensure a tight annular seal at depths exceeding 16,000 ft. It will also have the tensile strength, permeability, compressive strength, and expansive properties required for long-term durability, minimizing the potential for mechanical failures at temperatures exceeding 350oF and pressures exceeding 15,000 psi. The benefits of the proposed supercement include maximized production and elimination of costly remedial work for improved well economics. In addition, the supercement will be applicable worldwide, both for wells in deep, hot environments, and wells in less extreme environments that still require high stress resistance or where gas migration is a known problem |
