Portland Cement Strength

Cement paste strength is typically defined in three ways: compressive, tensile and flexural. These strengths can be affected by a number of items including: water-cement ratio, cement-fine aggregate ratio, type and grading of fine aggregate, manner of mixing and molding specimens, curing conditions, size and shape of specimen, moisture content at time of test, loading conditions and age (Mindess and Young, 1981[1]). Since cement gains strength over time, the time at which a strength test is to be conducted must be specified. Typically times are 1 day (for high early strength cement), 3 days, 7 days, 28 days and 90 days (for low heat of hydration cement). When considering cement paste strength tests, there are two items to consider:

  • Cement mortar strength is not directly related to concrete strength. Cement paste strength is typically used as a quality control measure.
  • Strength tests are done on cement mortars (cement + water + sand) and not on cement pastes.

Related Tests

Footnotes    (↵ returns to text)
  1. Mindess, S. and Young, J.F.  (1981).  Concrete.  Prentice-Hall, Inc.  Englewood Cliffs, NJ.