The invention relates to the field of
cement and concrete. The invention discloses special mixed
cement for on-site preparation of concrete as well as a preparation method and application. Except formixing and
grinding cement clinker and other raw materials, the mixed cement is prepared from the following components in percentage by
mass: 60%-80% of general
Portland cement of the 42.5 grade or above, 3.0%-6.0% of
gypsum, 5%-15% of limestone, 2%-29% of an admixture and 0.5%-3.0% of a functional additive. The general
Portland cement with the grade of 42.5 or above meets the requirements of GB175, and parameters of the general
Portland cement are controlled such that the
mass ratio of the micro
powder less than or equal to 3 [mu]m is less than or equal to 10%, the one-day
compressive strength is less than or equal to 12 MPa, the 3-day
compressive strength is more than or equal to 20 MPa, the 28-day
compressive strength is more than or equal to 45 MPa, the
water consumption of the standard consistency of the
cement paste is less than or equal to 28%, the alkali content is less than 0.6% in terms of 0.658 K2O + Na2O, and the
chloride ion content is less than 0.06%. The raw materials are wide in source, the mixed cement can be directly used for preparing or premixing concrete on site, no admixture or functional additive needs to be added again,
crack resistance, workability and themechanical property of the concrete are improved, and construction operation is simplified.