Colorado Ready Mixed Concrete Association (CRMCA) task force members feel that AASHTO T 23-93, Section 9.2.1, "Standard Specification for Making and Curing Concrete Test Specimens in the Field," allows wide variance when describing the initial curing condition requirements. Absence of specific direction, in regards to initial curing, leads to non-uniform practices by field technicians and inconsistent 28-day compressive strength results. It is believed that this inconsistency has led to increased costs associated with unnecessary over-design of Portland Cement Concrete (PCC) mixes, further testing of in-place PCC and the time-consuming claims process. CRMCA Technical Education Committee organized a task force to study the effect of various initial curing conditions on the compressive strength of concrete cylinders. Five different initial curing conditions and two in-place conditions were tested. Initially curing PCC test cylinders in saturated limewater provides more consistent surrounding temperature and a record of the surrounding temperature, and rigidly conforms to T 23-93, preventing any moisture loss. This is a practical curing method that leads to more consistent 28-day compressive strengths. More consistent results will reduce costs associated with unnecessary over-design of PCC mixes, further testing of in-place PCC and the time-consuming claims process. It is recommended that PCC cylinders, for checking the adequacy of laboratory mixture proportions for strength or as the basis for acceptance or quality control, shall be initially cured (24 to 48 hours) by full immersion in saturated limewater (lime concentrations as per AASHTO M 201-96).


  • English

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 33 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00800168
  • Record Type: Publication
  • Report/Paper Numbers: CDOT-R&D-SM-99-4,, Final Report
  • Created Date: Oct 11 2000 12:00AM