Title: Influence of Temperature on Strength Development of Fly-Ash and Silica-Fume Concretes
Author(s): H. Saricimen, M. Maslehuddin and 0.A Eid
Publication: Symposium Paper
Appears on pages(s): 59-78
Keywords: curing; fly ash; silica fume; strength; temperature.
The reduction in the useful-service life of reinforced concrete structures in the coastal areas of the Arabian Gulf is of major concern to the construction industry. The harsh climatic conditions, high level of chloride and sulfate contamination in the environment, low quality and contaminated aggregates, and substandard construction practices constitute the major causes of deterioration of reinforced concrete structures in less than 10 years in this part of the world. Since the concrete deterioration phenomena are strongly permeability dependent, mineral admixtures and industrial by-products, such as natural pozzolan, fly-ash, blast-furnace-slag, and silica-fume are increasingly used to improve its durability. Among the mineral admixtures and industrial by-products, fly-ash and silica-fume are considered to be more beneficial due to their superior performance in improving concrete durability. However, to attain beneficial properties, pozzolanic concrete needs early and extended curing compared with normal portland cement concrete. This is of particular concern in the Arabian Gulf environment, where the high ambient temperatures, solar radiation and blowing winds make curing a difficult process. Therefore in this study, the effect of temperature and drying as well as different curing conditions on the compressive strength development in normal Portland, silica-fume and fly-ash cement concretes was evaluated. The test specimens were cured in the laboratory and under field conditions, and tested 1,3,7, 14,28, 60 and 90 days after casting to evaluate the compressive strength development. The results indicated an increase in the compressive strength, in both the normal, fly-ash and silica-fume cement concrete specimens with the period of curing. Field curing had more negative effect on the strength development in concrete specimens containing fly-ash and silica-fume than in the plain concrete specimens. High temperature casting and curing increased the compressive strength in both plain and fly-ash concretes. Drying during curing produced the highest strength the silica-fume concrete specimens compared to plain and fly-ash concretes.