Title:
Influence of Construction Practices on Concrete Durability
Author(s):
Rasheeduzzafar, A. S. Al-Gahtani, and S. S. Al-Saadoun
Publication:
Materials Journal
Volume:
86
Issue:
6
Appears on pages(s):
566-575
Keywords:
aggregates; chlorides; concrete construction; concrete durability; consolidation; curing; marine atmospheres; reinforced concretes; reinforcing steels; sulfate resistance; Materials Research
DOI:
10.14359/2219
Date:
11/1/1989
Abstract:
Data have been developed on the effect of curing period, type of curing water, aggregate washing, and the degree of consolidation on corrosion resistance characteristics of concrete. The effects of curing period and consolidation have also been evaluated on the sulfate resistance of concrete. The results show that concretes cured for 28 days performed 4.4 times better in terms of corrosion of reinforcement and showed 59/40 (strength reduction/weight loss) percent improvement to sulfate resistance than concretes cured for 7 days. Type of curing water has important durability implications. When cured with service brackish water, the minimum chloride concentrations in slabs made with unwashed aggregates were found to be 1.52 and 1.72 times the threshold values at «-in. (12.7-mm) depth from the surface for 3 and 7 days of curing, respectively. Even when the aggregates were washed, the chloride concentration level at ¬-in. (6.3-mm) depth was found to be twice the threshold value for 7 days of curing by brackish water. In slabs cured in air for 24 hr after casting, the chloride concentration at «-in. (12.7-mm) and 1«-in. (38.1-mm) depths were found to be 2 and 1.4 times greater than the comparative values for slabs cured with wet burlap in the first 24 hr after casting. The beneficial effect of aggregate washing is, on an average, of the order of 15 to 20 percent for the aggregates tested in this study. Degree of consolidation has a significant effect on concrete durability. With 60 percent consolidation effort, the time to initiation of corrosion was found to be 76 percent and sulfate attack deterioration to be 1.9/1.4 (strength reduction/weight loss) times more than those for specimens where full consolidation is achieved.