Estimation of mortars compressive strength at different curing temperature by the maturity method

• At early age, compressive strengths increase linearly with the curing temperature.
• At later age, mineral additions are activated and cause an increase in strength.
• With mineral addition; compressive strengths are less influenced by temperature rise.
• Compressive strength is predicted according to a new maturity index expression.
• The new maturity index provides the temperature effect on cement paste at later age.

Two set of mortars were made with three mineral additions to verify the relationship between compressive strength and maturity at later age. One cured in steam room at constant temperature of 20, 30, 40 and 50 °C and the second cured under variable temperature history. It was found that a limited maturity index of 350 °C days exists beyond which the relationship between strength and maturity is not unique. The newly proposed maturity index allows a better correlation between strength and maturity at later age and takes into consideration the deterioration of microstructure with temperature rise. Later age strength can be predicted using the relationship strength-maturity at early age with a correlation coefficient ranging from 0.89 to 0.98.