Different anti-icing agents are used in various locations in Ontario to meet the specific climate needs of the area in order to minimize, or help remove, snow and ice build-up. These anti-icing agents are generally applied in liquid form and, due to their low freezing temperatures, are able to stay liquid, thus also allowing them to penetrate concrete structures. It has been shown in previous studies that the cations of some of the solutions can react with the cementitious materials to form precipitates of expansive nature. In this project, concrete exposed to the different solutions has been subjected to freezing and thawing both in laboratory tests and in outdoor exposure and to compression testing. However, the salts prevented freezing at the lowest temperatures tested. Therefore, it has been observed that reactions with the calcium and magnesium chlorides can have a positive effect at early ages but a potentially detrimental effect over the long term. The penetration of salt into the dry concrete was determined to be very fast and resulted in a rapid initial increase in the concrete compressive strength but little subsequent strength gain, whereas the strength of concrete exposed to water continues to increase over a longer period.

This paper presents the preliminary results of a study examining the stress vs. strain behavior, stress relaxation, and corrosion resistance of six candidate high-strength stainless steels (HSSSs) for potential use as corrosion-resistant prestressing reinforcement in concrete structures. Austentic grades 304 and 316; duplex grades 2101, 2205, and 2304; and a precipitation hardened martensitic grade 17-7 were selected for the investigation and cold drawn to diameters of approximately 4 mm (0.16 in). Tensile strengths of 1290 to 1550 MPa (185 to 225 ksi) were achieved in the cold-drawn HSSS wires. 1000-hr stress relaxation of all candidate HSSSs was predicted to be between 6 and 8 % based on the results of short-term relaxation tests conducted at 70% ultimate tensile capacity. Cyclic polarization testing for chloride-induced corrosion resistance determined that in alkaline pore solutions, 2205 and 2304 exhibited low corrosion susceptibility and 304 exhibited moderate corrosion susceptibility at 0.5 M chloride concentrations. When exposed to carbonated pore solutions with 0.5 M chloride, grades 2205 and 2304 exhibited low and moderate corrosion susceptibility, respectively. Duplex grade 2205 exhibited superior corrosion resistance in all cases. Based on these results, optimal HSSSs were identified as duplex grades 2205 and 2304.

The purpose of this report is to compare the corrosion resistance of several proprietary combinations of stucco and wire reinforcing mesh (lath) to enhance corrosion protection against chloride environments. The lath is produced by spot welding galvanized steel wire and was tested pre-welding, post-welding and after a post-weld chromate treatment. The effect of the weld joint and the chromating on the initial rapid corrosion, typical of zinc embedded in cement-based materials, was first investigated. Despite the loss of zinc at the welds, there was little difference in corrosion rates of the non-welded and welded specimens. The chromating, however, was found to be highly beneficial in eliminating the initial rapid corrosion. A second set of tests investigated the comparative corrosion behavior of the lath in OPC-based stucco and a commercial calcium-aluminate-based stucco (Stucco A) in chloride solution. The study showed the Stucco A to provide less protection than the OPC stucco. Addition of lime to Stucco A, which is not recommended by the manufacturer, resulted in greater corrosion protection.

The presence of chlorides in cementitious materials results in corrosion of the embedded metallic materials. Early construction practices (pre 1960s) relied on admixed calcium chloride to accelerate the early strength gain of concrete. Until the 1950s, few publications focused on the effects of chlorides in concrete on corrosion and the use of chlorides was well established. However, in the 1960s significant publications reported on the effects of chlorides on the corrosion of prestressed wires and strands – these publications were the result of several failures of prestressed systems. Later, significant research was performed on the corrosion of steels in cementitious materials―a significant portion of this work attributable to the researchers being recognized in this symposium: Brian Hope and Morris Schupack. Their considerable efforts led to new knowledge regarding corrosion durability of reinforced and prestressed systems. Recently, ACI Committees 201 and 222 standardized limits on allowable admixed chlorides in the constituent materials. However, more standardization is needed―ACI Committees 318 and 349 report different admixed chloride limit requirements than Committees 201 and 222. This paper provides an overview of past research, analyzes the effects of chlorides on service life and economy and provides data from a research project. Using this information, the authors propose a standardized limit for chlorides in concrete.

The repair and rehabilitation of corroding infrastructure systems consumes significant resources. It is well documented that significant value is gained by using durable materials that exhibit long-term, repair-free performance. In the US, most state highway agencies (SHAs) are approached by material producers and requests are made to evaluate the material for possible use in the infrastructure system. SHAs have limited resources and are in need of new evaluation methods that are reliable, fast, and cost-effective. This research evaluated four different accelerated test methods for evaluating the corrosion performance of steel in cementitious materials. Results were compared with results from the commonly used standard ASTM G 109 test method. The corrosion performance of conventional bars, stainless steel bars, galvanized bars, and epoxy-coated bars were evaluated using concrete and mortar mixtures with different water-cement ratios and containing different amounts of a corrosion inhibitor. The effectiveness, time requirements, complexity, and costs of the new test methods were compared with the ASTM G 109 method. This research found that the Rapid Macro-cell Test (RMT) is relatively simple to perform and provides reasonable results for most products in a reasonable time frame with minimal relative cost.