The objective of this research was to investigate emulsion-treated base (ETB) frost susceptibility in terms of both freeze-thaw cycling and frost heave. The research performed in this study involved laboratory testing of ETB materials sampled from both the Redwood Road and 7800 South reconstruction projects in northern Utah. The effects of freeze-thaw cycling were evaluated by comparing the stiffness and strength of tested specimens to the same properties of control specimens not subjected to freeze-thaw cycling. Frost heave testing enabled evaluation of the effects of emulsion content and degree of curing on the volumetric stability of ETB materials during sustained freezing. Since permeability affects the frost susceptibility of a material, samples were also prepared to specifically evaluate the effect of curing condition on the permeability of the two base materials when treated with emulsion. The results of freeze-thaw testing showed that both the Redwood Road and 7800 South specimens experienced decreases in modulus as a result of freeze-thaw damage. The results also showed that the Redwood Road specimens experienced substantial decreases in strength as a result of freeze-thaw damage. The specimens from 7800 South did not exhibit such strength loss; since those specimens initially had much lower modulus and unconfined compressive strength values than the Redwood Road specimens, they were less susceptible to stiffness and strength loss during the freeze-thaw test. Results for the frost heave tests showed that the untreated base materials were not susceptible to frost heave and that the addition of emulsion, with or without curing, did not change the frost heave behavior in a practically important way. While susceptibility to frost heave is not expected to be a problem with these base materials, the laboratory results revealed a significant increase in the permeability of the ETB specimens after curing, which could facilitate greater freeze-thaw damage. In consideration of these research results, engineers should ensure proper material sampling and laboratory testing to assess the efficacy of emulsion treatment for a given project. ETB to be constructed in cold regions should be subjected to freeze-thaw testing during the design phase, and designers should be aware that curing of the ETB may dramatically increase permeability and therefore increase frost susceptibility.

Master of Science / Department of Civil Engineering / Kyle Riding / Concrete is most widely used material in construction industry, which is made up of cement, water and aggregates as its major ingredients. Aggregates contribute to 60 to 75 % of the total volume of concrete. The aggregates play a key role in the concrete durability. The U.S Midwest has many aggregates that can show distress in the field under freezing and thawing conditions. The objective of this research was to determine if the Test Method for the Resistance of Unconfined Coarse Aggregate to Freezing and Thawing, method CSA A23.2-24A, could be used to differentiate good from poor performing aggregates in concrete. In this study fifty one KDOT aggregates (including twelve ledge and thirty nine production samples) were tested for freeze thaw resistance using CSA A23.2-24A test method and were compared to the results of the standard KDOT aggregate qualification tests. In addition to performing the CSA test method using a 3% sodium chloride solution, a subset of the aggregates were tested using either a 3% magnesium chloride or calcium chloride solution to determine the effects of the salt type on the aggregate performance. No correlation was found between the CSA A23.2-24A test method results and the standard KDOT aggregate qualification tests. The results also indicated that the mass loss in the CSA A23.2-24A was similar for the aggregate sizes tested. The use of alternate salt solutions like MgCl2 and CaCl2 resulted in increased freeze thaw mass loss in limestone aggregates.