Title: Extreme Concrete

Author(s): K. W. Awad, H. Mazen, and R. Fakih

Publication: Symposium Paper

Volume: 209

Issue:

Appears on pages(s): 435-460

Keywords: admixture dosage; concrete temperature; heat generation; heat loss; high early strength; hot weather concrete; long haul; retarder; setting time; superplasticizer; temperature rise; W/C; workabiIity retention

DOI: 10.14359/12514

Date: 9/26/2002

Abstract:
The durability and perme&i&y of concrete are of special concern in the Arabian Gulf due to the prevailing aggressive weather conditions. Very few practical examples showing the ability of the local ready-mixed industry to adapt to extreqie hot weather, characteristic of this region of the world, have and analyzed. The following paper describes extreme concrete properties in two particular projects in Saudi Arabia demonstrating how the local concrete industry has used specific measutes to produce high-performance concrete in very hot weather. In the first project concrete was hauled for 8 hours in hot weather using high dose of standard retarders and superplasticisers and following rigorous measures to control the mix temperature. In the second project high-strength high-performance concrete was hauled for 45 minutes at an ambient temperatup of 40" C and achieved 24 hours strength in excess of 50 MPa. It is concluded that controlling the temperature of fresh concrete in hot weather should be primarily based on parameters related to cost, workability retention and long-term strength. Besides, the cited examples'demonstrated how the use of admixtures in hot weather could be very beneficial even if the dosage considered did not comply with ASTM C 494 requirements and the manufacturer standard recommendations.