Title: Analysis of Mortar Long-Term Strength with Supplementary Cementitious Materials Cured at Different Temperatures

Author(s): Karim Ezziane, El-Hadj Kadri, Abdelkader Bougara, and Rachid Bennacer

Publication: Materials Journal

Volume: 107

Issue: 4

Appears on pages(s): 323-331

Keywords: compressive strength; limestone; mortar; natural pozzolan; slag; supplementary cementitious materials; temperature

DOI: 10.14359/51663857

Date: 7/1/2010

Abstract:
This experimental study was done to quantify the evolution of the mechanical strength modifications resulting from the presence of several supplementary cementitious materials (SCMs) in the mixture design of a mortar hardening under various curing temperatures. Mortars were made with various replacement levels of the cement by mass: 30 and 50% for slag; 10, 20, 30, and 40% for natural pozzolan; and 5, 15, and 25% for limestone powder. Samples were stored in a saturated-humidity moist room under various temperatures, namely 68, 104, and 140°F (20, 40, and 60°C). The results enable the verification of some hardening properties, such as half-strength age and long-term strength. The experimental results of half-strength age perfectly match with the previous studies that show a slower hydration of the cement with an increase in SCM. This effect decreases with the curing temperature. The long-term strength—depending on the curing temperature—is expressed by a parabolic expression contrary to the classical linear form in the case of ordinary portland cement (OPC). This new expression is more accurate in predicting the concrete longterm strength versus curing temperature with a part of cement replaced by SCM. Many experimental results obtained by other researchers have supported the proposed expression with a satisfactory accuracy, encouraging its generalization.