Title:
Resistance to chloride intrusion of concrete cured at different temperatures
Author(s):
Rachel J. Detwiler, Knut O. Kjellsen, and Odd E. Gjorv
Publication:
Materials Journal
Volume:
88
Issue:
1
Appears on pages(s):
19-24
Keywords:
cement pastes; chlorides; concretes; concrete durability; corrosion resistance; curing; microstructure; permeability; temperature; portland cements; tests; Material Research
DOI:
10.14359/2326
Date:
1/1/1991
Abstract:
Numerous investigations of the pore structure of portland cement paste have demonstrated that higher curing temperatures result in a coarser pore structure. Elevated curing temperatures are known to reduce the long-term strength of concrete. It is reasonable to expect reductions in durability as well, yet very little research has been done on this topic. The paper describes a preliminary investigation of the ability of concrete to withstand the corrosion of reinforcing steel. Concretes of 0.40, 0.50, and 0.58 water-cement ratio were made without chemical or mineral admixtures. Mixing and curing took place at constant temperatures of 5, 20, and 50 C (41, 68, and 122 F). Curing times were varied to allow for an equal degree of hydration of approximately 70 percent. Two types of tests measured the rate of chloride diffusion. An accelerated corrosion test compared the ability of the concretes to withstand the corrosion of reinforcing steel. Both test methods are described in detail. The results of both tests indicate clearly that, at a given water-cement ratio, elevated curing temperatures reduce the ability of portland cement concretes to withstand chloride diffusion and the consequent depassivation of reinforcement. This effect is more pronounced at lower water-cement ratios. These findings should be taken into account in the construction of concrete structures for which durability is a concern.