Title:
The Effect of Thick Concrete Cover on the Maximum
Flexural Crack Width under Service Load
Author(s):
Hanna M. Makhlouf and Faris A. Malhas
Publication:
Structural Journal
Volume:
93
Issue:
3
Appears on pages(s):
257-265
Keywords:
beams (supports); crack width and spacing; corrosion; cover;
durability; flexural strength; serviceability; tests.
DOI:
10.14359/9685
Date:
5/1/1996
Abstract:
Durability of reinforced concrete is of prime interest in the Arabian Gulfregion. It has been realized that the most practical means to protect the steel against corrosion is by increasing concrete cover. However, American and British design codes couple the increase in concrete cover to a correspond-ing increase in the maximum crack width under service load. This contradiction undermines the objective of the concrete cover increase. To investigate the effect of the increase in concrete cover on the maximum crack width, tests were conducted on two groups of rectangular beams. The first group of 24 b earns examined the effect of doubling the concrete cover on the maximum crack width. The second group of eight beams used a 50- mm concrete cover (per the recommendation of local professionals) with varying reinforcement. Comparisons of the test results with the computed values for the maxi-mum crack width according to ACI 318-89 and BS 81 lo-85 have shown that the codes overestimate the sensitivity of maximum crack width to the increase in concrete cover. It has also been shown that the use of a 50-mm concrete cover leads to acceptable levels of crack widths under service loads. The ability of the codes’ equations to correlate with the experimental results is observed to depend on the reinforcement ratio and the load level.