Title:
Placing and Shrinkage at Extreme Temperatures
Author(s):
A. A. Almusallam, M. Abdul-waris, M. Maslehuddin, and A. S. Al-gahtani
Publication:
Concrete International
Volume:
21
Issue:
1
Appears on pages(s):
75-79
Keywords:
cracking; concretes; environments; evaporation; hot weather construction; plastic shrinkage
DOI:
Date:
1/1/1999
Abstract:
The effect of environmental conditions, particularly those in hot and arid regions, on plastic shrinkage cracking in concrete was investigated. Concrete specimens made using typical mix proportions were exposed to varying temperatures, humidity, and wind conditions. The effect of exposure conditions on parameters influencing plastic shrinkage cracking of concrete, namely rate of evaporation, and time to initiation of cracks and their intensity were evaluated. The results of this study indicate that environmental conditions significantly affect plastic shrinkage cracking of concrete. For example, concrete specimens exposed to low humidity cracked earlier than those exposed to high humidity. Similarly, when there was no wind, the rate of evaporation decreased with increasing humidity. However, under windy conditions, high relative humidity had no significant effect on the rate of water evaporation. Further, cracks were observed at evaporation rates ranging from 0.2 to 0.7 kg/m2/hr (0.041 to 0.143 lb/ft2/hr)as against a value of 1 kg/m2/hr (0.2 lb/ft2/hr) recommended by ACI Committee 305. Further, the results indicate that the rate of evaporation controls the intensity of plastic shrinkage cracks.