THE EFFECTS OF DEICERS ON PAVEMENTS

The remarkable change in the weather pattern across the US has caused home and small business owners to increase the use of salts on their pavements and sidewalks to limit slip and fall accidents. In addition, deicing companies have modified their products to make them more effective in melting snow and ice and to consider their environmental effects. Winter weather patterns in parts of the US have caused owners to notice that their concrete pavements have shown signs of early scaling leading them to question the cause and effects of current deicers on the market. These effects motivated this NSF REU research project to determine what can be done to alleviate the problem.

To investigate this issue a series of concrete specimens were made at the current standard strength of 3000 psi along with specimens made at both 3500 and 4000 psi to determine if strength would increase salt resistance. Three salt solutions were made from: FastMelt (MgCl); Safe Step (NaCl) and the Tennessee DOT brine salt used on roadways. An environment was simulated in the lab for both wet/ dry and freeze/thaw cycles for concrete beam specimens over a period of 60 days. After this, the beams were regularly measured for weight and length changes over this course of time to determine effects of exposure. In addition, slabs were cast to pond various salt mixtures to determine chloride penetration over the same 60 days, with part of the slab covered by a commercial concrete sealant, and the other part left exposed to salt intrusion. The slabs were then cored and a powder sample was extruded for a chemical test to determine the concentrations of chloride in the sample.

Due to the resilient nature of concrete, the results of the investigation were most inconclusive. In order to see and measure more definitive results, it was determined more exposure time and freeze/thaw cycles were required/recommended. The exception of this was in the use of commercial concrete sealants, which showed significant protection from and reduction of permeation of chlorides into the samples. The industry standard for residential and light commercial concrete projects does not mandate a concrete sealer and this research does indicate the beneficial use of a sealant to protect against deicer salts.