Q.: What papers or publications do you know of regarding the exposure of concrete surfaces to high temperatures (1500°F)? What can you recommend from personal experience to keep the surface of concrete from spalling when shock-exposed to high temperature?
A.: Portland cement concrete cannot withstand exposure to 1500°F without undergoing severe strength loss and cracking because the hardened paste dehydrates at such high temperatures. Concrete made with high alumina cement and refractory aggregates might be able to withstand such exposure conditions. For somewhat lower temperatures, portland cement concrete made with refractory aggregates, crushed brick, slag or limestone will perform better than other concrete. Prior to exposure to high temperatures, the concrete should be thoroughly dried, preferably by heating the concrete slowly to about 150 to 200°F and circulating hot air past the surfaces of the concrete for several days. Some publications that might be useful are:
- Melvin S. Abrams, "Compressive Strength of Concrete at Temperatures to 1600°F," Temperature and Concrete, ACI Publication SP-25. (This publication also contains other articles on the effects of temperature on concrete.)
- Refractory Concrete, ACI Special Publication SP-57.