Four variables that affect the success of lime as an antistripping agent were evaluated: (a) four methods of adding two types of lime to asphalt-aggregates, (b) four lime products, (c) two different aggregate sources, and (d) air voids. Effects of the four variables on moisture sensitivity were evaluated by determining the resilient modulus and the tensile strength of samples before and after one cycle of the Lottman accelerated conditioning procedure (a freeze-thaw cycle subjecting water-saturated samples to freezing at -20 deg F andthawing in a 140 deg F water bath). The effects of the variables ontemperature susceptibility were evaluated by determining the resilient modulus values at four different test temperatures. The following conclusions can be drawn from this research project: (a) quicklimeadded to the asphalt or to the dry aggregate can be detrimental to the mixture; (b) dolomitic lime can improve mixture properties to the same degree as hydrated lime; (c) mixture properties can be enhanced by the addition of hydrated lime, regardless of the moisture susceptibility of the untreated mixes; (d) an increase in the volume of lime used can further improve the mixture properties; and (e) air voids significantly affect mixture properties, regardless of lime variations.(A).
Abstract